Recovery-Termination Failure in ME/CFS

Abstract

Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) is clinically defined by post-exertional malaise (PEM), a delayed and disproportionate worsening of symptoms following physical, cognitive, or autonomic stress. At a physiological level, ME/CFS reflects a failure to safely regulate blood flow and metabolic scaling during stress. Instead of increasing perfusion—particularly to skeletal muscle, the body’s largest dynamic vascular bed—and returning cleanly to baseline, the system enters a prolonged and destabilized recovery phase.

Building directly upon the unified model of PEM proposed by Wirth and Scheibenbogen, we present an upstream mechanistic extension that integrates major ME/CFS hypotheses within a single hierarchical framework. Genetic termination vulnerability, autonomic timing instability, oscillatory shear stress, endothelial glycocalyx disruption, and skeletal muscle perfusion heterogeneity converge to increase intracellular calcium pulse frequency at endoplasmic reticulum–mitochondria contact sites. When recovery-phase calcium signals overlap before decay completes, redox persistence and immune-duration amplification increase the probability of sustained sterol-sensing engagement.

We propose that disease acquisition occurs when sterol-dependent membrane lipid renewal fails to reset during recovery windows. Persistent INSIG-mediated suppression of SCAP–SREBP trafficking converts reversible perfusion instability into chemically stabilized non-termination. Execution-surface remodeling, shear–buffering mismatch, routing inefficiency, and regulatory engagement constraint then deepen and rigidify the acquired state without redefining its hinge.

This framework does not compete with existing hypotheses; it hierarchically integrates them. The central, falsifiable prediction is that stress-window sterol-reset failure—rather than baseline inflammation or energy deficiency—defines disease acquisition in ME/CFS.

2. Introduction

Toward a Unified Recovery-Control Architecture

Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) is clinically defined by post-exertional malaise (PEM), a delayed and disproportionate worsening of symptoms following physical, cognitive, or autonomic stress. PEM is not a secondary feature of the illness—it is its defining physiological signature. At its most fundamental level, ME/CFS reflects a failure to safely regulate blood flow and metabolic demand during stress. Instead of increasing perfusion to match demand and then returning smoothly to baseline, the system enters a prolonged and destabilized recovery phase characterized by delayed symptom amplification and multi-system dysfunction.

Because skeletal muscle represents the largest rapidly adjustable perfusion demand in the body, exertion most reliably exposes this defect. Wirth and Scheibenbogen emphasized the central role of impaired adrenergic signaling, endothelial dysfunction, and defective oxygen extraction in skeletal muscle [1], [33], [34], establishing that PEM reflects a systemic failure of coordinated stress adaptation rather than isolated organ pathology. The present framework builds directly upon that unified physiological model of PEM and extends it upstream into a hierarchical recovery-control architecture.

In healthy physiology, stress induces tightly coordinated increases in vascular tone, perfusion, intracellular calcium signaling, metabolic throughput, and autonomic output. These responses are transient. Signal amplitude rises to meet demand and decays once demand subsides. Recovery is therefore an actively regulated process governed by both the frequency and duration of signaling events. ME/CFS emerges when recovery termination becomes unreliable and fails to consistently complete.

Multiple hypothesis frameworks have attempted to explain this failure. The Cell Danger Response model proposes persistence of a regulated defensive metabolic state [2], [4], and metabolomic studies demonstrate systemic energy-handling alterations in ME/CFS [3], [8]. Broader syntheses identify abnormal energy metabolism, immune dysregulation, and vascular dysfunction as converging features [9], [10]. Other models propose specific persistence mechanisms, including the IDO metabolic trap [6], endothelial senescence [7], fibrinaloid microclot amplification of vascular instability [12], hydrogen sulfide dysregulation [14], and membrane substrate deficiencies affecting neuronal and metabolic regulation [13].

Early mechanistic work also proposed that endoplasmic reticulum–mitochondria contact sites (MAMs) may serve as a sustaining node in ME/CFS, with redox–ROS feedback at the ER forming a self-reinforcing loop (Kalafatis, [5]). Subsequent hypothesis work connected sulfation biology, heparan sulfate dynamics, and oxysterol handling to membrane–liver regulatory stress (Kalafatis, [90]), anticipating later findings linking glycocalyx integrity and sterol regulation to vascular resilience.

These frameworks differ in emphasis but converge on a common observation: recovery from stress becomes unstable and fails to terminate normally.

Across hypotheses, two destabilizing dimensions consistently recur:
• Increased signaling frequency
• Prolonged signaling duration

These are not competing explanations; they are orthogonal parameters governing recovery termination.

At the organismal level, impaired baroreflex buffering increases arterial pressure variability and shear heterogeneity [15], [22]. Shear encodes temporal information, not merely magnitude. Endothelial mechanotransduction depends on precise coordination between rapid and delayed nitric oxide–generating pathways [25], [27]. When baroreflex precision degrades, shear becomes oscillatory and spatially heterogeneous, increasing intracellular calcium pulse frequency [23]–[26]. If inter-pulse intervals fall below decay kinetics, recovery-phase signals begin to overlap.

At the cellular level, repeated calcium overlap at ER–mitochondria contact sites generates localized redox pressure and slows thiol restoration [36], [39]. When signal duration exceeds restoration capacity, redox state becomes a persistence variable. In parallel, prolonged interferon–STAT1 activation increases cholesterol 25-hydroxylase expression and 25-hydroxycholesterol production [40], [50], [51], increasing sterol-sensing engagement probability.

The unresolved question is not whether instability occurs—but how instability becomes fixed.

We propose that frequency and duration pressures converge at a sterol-regulated membrane renewal checkpoint within the endoplasmic reticulum. When sterol-sensing engagement persists across recovery cycles, SCAP–SREBP–dependent lipid-reset authorization fails to resume [57], [58]. Coordinated sterol-responsive ER-associated degradation further contracts membrane renewal bandwidth [61]–[63]. Reversible recovery instability transitions into chemically stabilized non-closure. This sterol-dependent reset failure constitutes the acquisition hinge.

Importantly, this transition does not require persistent infection, constitutive cytokine escalation, primary mitochondrial collapse, or absolute NAD depletion. Acute infection may amplify entry by increasing signaling frequency, redox flux, and interferon duration simultaneously [2], [39]. However, once membrane renewal suppression stabilizes recovery non-termination, the system becomes self-reinforcing. Mechanical instability increases redox persistence; redox persistence increases sterol engagement; sterol engagement lowers the threshold for subsequent overlap.

In this formulation, this framework is not a competing hypothesis layered onto prior models. It is an upstream integrative architecture of PEM that simultaneously accommodates vascular–autonomic dysfunction [1], skeletal muscle oxygen-extraction failure [32]–[34], purinergic signaling [2], interferon-duration dysregulation [40], redox imbalance [39], glycocalyx perturbation [89]–[92], membrane remodeling [69], [73], and sterol regulatory biology [57]–[63] without contradiction.

ME/CFS acquisition therefore follows a coherent progression:
Autonomic mistuning and shear variability → Increased calcium pulse frequency and recovery-phase overlap → Redox persistence and immune-duration amplification → Sustained sterol-sensing engagement → Suppressed membrane lipid renewal → Chemically stabilized recovery non-termination

This model reframes ME/CFS as a disorder of recovery control and membrane reset timing. Skeletal muscle reveals the defect; sterol-dependent authorization failure stabilizes it. The detailed mechanistic structure of this acquisition and its layered persistence architecture are developed in the sections that follow.

3. Autonomic Mistuning, Glycocalyx Integrity, and Shear as the Primary Destabilizer

Recovery termination begins at the level of perfusion control. Before redox–thiol chemistry, sterol engagement, or membrane remodeling occur, the organism must regulate arterial pressure and microvascular shear with temporal precision. In healthy physiology, baroreflex buffering dampens transient blood pressure fluctuations, maintaining stable shear profiles across vascular beds [15],[22].

Shear forces, however, are not transmitted directly to the endothelial membrane. They are filtered through the endothelial glycocalyx — a heparan sulfate (HS)–rich meshwork that functions as both a mechanical and electrostatic buffer between circulating blood elements and the plasma membrane. An intact glycocalyx distributes shear evenly, attenuates high-frequency oscillations, and preserves coherent membrane tension waveforms required for phase-locked nitric oxide signaling [25],[27],[84]. HS-binding proteins regulate coagulation, immune signaling, and receptor clustering, underscoring the glycocalyx as an active signaling scaffold rather than a passive barrier [92].

In ME/CFS, this upstream precision degrades.

Autonomic mistuning—whether triggered by orthostatic load, cognitive stress, emotional activation, or exertion—reduces baroreflex gain and increases arterial pressure variability [15],[22]. Oscillatory pressure changes propagate into the microcirculation as heterogeneous shear stress [25]. When glycocalyx integrity is compromised by repeated shear stress and redox perturbation, its buffering capacity declines. Reactive oxygen species are potent inducers of heparanase, the sole mammalian enzyme capable of degrading HS chains [91]. HPSE-mediated glycocalyx remodeling promotes cytokine release, lipoprotein redistribution, and thrombosis under disturbed flow conditions [91], converting coherent laminar filtering into patchy, heterogeneous force transmission.

Age-dependent alterations in HS abundance and structure further demonstrate that glycocalyx composition is dynamically regulated and susceptible to structural drift over time [89]. Age-associated MAM dysfunction and altered calcium handling have likewise been linked to declining cellular resilience [85], reinforcing that membrane–contact-site precision depends on coordinated lipid and calcium regulation.

Shear is not a scalar quantity; it encodes temporal structure. Loss of glycocalyx-mediated filtering converts laminar flow signals into spatially irregular membrane tension spikes. Under these conditions, mechanotransduction becomes temporally irregular, increasing intracellular calcium pulse frequency and recovery-phase overlap probability [23]–[26].

This instability precedes and conditions all downstream molecular events.

3.1 Glycocalyx Integrity as a Timing Buffer

The endothelial glycocalyx functions as a mechanical timing filter. Through HS proteoglycans and their linkage to cortical cytoskeletal networks, shear forces are distributed across the endothelial surface rather than concentrated at focal tension points [25]. This distribution maintains coherent membrane deformation patterns and stable mechanosensory activation.

Under laminar flow with intact glycocalyx architecture, endothelial cells align with the direction of flow and sustain quiescent, phase-locked nitric oxide signaling [25],[27]. When glycocalyx structure is thinned, fragmented, or patchy—particularly under oscillatory flow and oxidative stress—force transmission becomes heterogeneous. Mechanosensory activation shifts from coherent waveform signaling to stochastic tension spikes.

Timing precision—not mean perfusion—determines whether shear remains informational or destabilizing.

As oscillatory components increase and glycocalyx filtering declines, the probability that consecutive mechanotransduction pulses occur before intracellular calcium fully decays rises [23],[26]. The system transitions from stable recovery termination to frequency-driven overlap.

3.2 Mechanotransduction Timing Circuits

Shear sensing is mediated by integrated ion-channel and purinergic signaling networks in which PIEZO1 serves as a principal mechanosensor [23],[25]. Critically, PIEZO1 responds to membrane tension rather than shear magnitude directly. Glycocalyx integrity therefore shapes PIEZO1 activation indirectly by modulating the membrane tension field imposed by flowing blood.

PIEZO1 activation initiates ATP release and engages G protein–coupled pathways that coordinate nitric oxide production through temporally distinct arms [23],[24],[26]. One arm activates Gαq/Gα11-dependent signaling with rapid kinetics; a second engages Gαs–cAMP–PKA pathways with delayed, sustained effects [24],[26]. In parallel, PIEZO1 activation drives SERCA-dependent endoplasmic reticulum calcium loading and IP₃R2-dependent calcium release [26].

Under physiological shear and intact glycocalyx buffering, these pathways remain phase-locked. Nitric oxide output aligns temporally with mechanical demand, and intracellular calcium signals decay before subsequent pulses [27]. When glycocalyx integrity is reduced and shear becomes heterogeneous, this temporal coordination degrades.

Recorded ME/CFS vascular phenotype: Multi-omic plasma proteomics in ME/CFS identifies elevated vascular remodeling signals (including THBS1) and altered endothelial-associated proteins, and reports reduced PIEZO1 abundance in ME/CFS plasma proteomic profiles [93]. (Use [93] specifically for THBS1/PIEZO1 in ME/CFS.)

3.3 Nitric Oxide Phase-Locking Degradation

Increased arterial pressure variability produces oscillatory PIEZO1 activation and irregular ATP release, perturbing coordination between rapid Gαq/Gα11–Akt signaling and slower Gαs–PKA pathways [23]–[26]. Nitric oxide output becomes temporally and spatially imprecise [27].

Simultaneously, oscillatory flow increases superoxide generation, promoting nitric oxide–superoxide coupling and diverting nitric oxide away from soluble guanylate cyclase signaling toward radical chemistry [28],[29],[84]. Peroxynitrite formation further perturbs redox balance [29]. THBS1-driven inflammatory signaling has been shown to promote interferon responses and mitochondrial ROS production in aging models [87], further linking endothelial stress to redox persistence.

Recorded in ME/CFS: Elevated circulating THBS1 (and related vascular remodeling factors) is observed in ME/CFS plasma proteomics and supports a vascular dysfunction phenotype relevant to impaired phase-locking and shear heterogeneity [93].

This represents degradation of control quality rather than nitric oxide deficiency [27],[28]. Loss of phase-locking increases variability in intracellular calcium pulse timing. When inter-pulse intervals fall below decay kinetics, recovery-phase calcium signals overlap. Frequency destabilization is established.

3.4 Oscillatory Shear, Glycocalyx Patchiness, and Overlap Probability

The critical transition occurs when pulse frequency exceeds termination capacity.

Repeated mechanotransduction events drive:
Increased intracellular calcium pulse frequency → Incomplete decay between pulses → Persistent ER–mitochondrial contact → Elevated probability of redox–thiol perturbation [36]–[39]

Glycocalyx patchiness amplifies this transition by:
• Increasing focal membrane tension spikes
• Increasing near-wall particle residence time
• Enhancing lipoprotein docking heterogeneity
• Destabilizing membrane microdomain organization

Autonomic stress alone—without immune persistence or sterol biology—can therefore elevate overlap frequency.

Chemical stabilization does not occur at this stage. Lipid-reset authorization remains intact, and thiol modifications remain reversible [57],[58]. However, once frequency-driven overlap is established, the system becomes susceptible to duration amplification and scaffold sensitization [39]–[41],[50].

Autonomic–shear destabilization, modulated by glycocalyx integrity and endothelial stress amplifiers, thus represents the primary upstream driver of recovery-phase instability. It establishes the frequency arm of destabilization and sets the stage upon which duration-amplified immune signaling and redox–thiol persistence can convert transient overlap into stabilized non-termination.

This leads directly to skeletal muscle, where perfusion scaling is maximal and frequency-driven shear variability is most pronounced [30]–[35].

4. Skeletal Muscle as the Primary PEM Generator

(Fully aligned to numbering 1–84)

Post-exertional malaise (PEM) is most reliably triggered by physical activity. To explain this specificity, the acquisition architecture must identify the tissue in which physiological stress most consistently exposes recovery-termination fragility.

Skeletal muscle occupies this role.

Among all organ systems, skeletal muscle exhibits the largest dynamic perfusion range in the body. During exertion, local blood flow to active muscle groups can increase approximately 20–50-fold relative to rest—far exceeding the dynamic range of cerebral, renal, or splanchnic beds [30],[31]. This scaling is spatially heterogeneous: motor units are recruited asynchronously, capillary beds are dynamically opened, and flow is redistributed on subsecond timescales [30],[31].

Shear stress at the endothelial surface is therefore determined not simply by total cardiac output, but by velocity gradients and capillary recruitment geometry [25],[30]. When perfusion distribution is imperfect, localized velocity spikes, narrowed microchannels, and oscillatory shear domains emerge [25],[31]. These focal disturbances increase:

• Endothelial mechanotransduction variability [23]–[26]
• Nitric oxide phase misalignment [27],[28],[84]
• Red blood cell deformation stress [77]
• Microvascular transit heterogeneity [75],[76]

Under healthy control, shear remains informational. Mechanotransduction circuits remain phase-locked, and intracellular calcium signals decay before the next pulse [25],[27]. Under autonomic mistuning and baroreflex suppression, however, shear heterogeneity increases and timing fidelity degrades [15],[22]–[26]. Calcium pulse frequency rises, increasing the probability that recovery-phase decay does not complete.

Skeletal muscle therefore becomes the dominant generator of overlap frequency under physical load.

Oxygen Extraction Failure and Recovery-Phase Instability

In ME/CFS, invasive cardiopulmonary exercise testing demonstrates preserved cardiac output and arterial oxygenation during exertion alongside impaired peripheral oxygen extraction [32]–[34]. Oxygenated blood returns with elevated venous saturation, indicating that delivery remains intact while utilization fails. The physiological bottleneck localizes to the skeletal muscle–microvascular interface rather than to central cardiopulmonary limitation [32]–[34].

Exertion therefore reveals a characteristic pattern:
Delivery intact.
Utilization failed.

This mismatch generates intermittent micro-ischemia–reperfusion–like stress during recovery. During exertion, compensatory mechanisms may transiently preserve contractile output. However, during recovery, unresolved perfusion heterogeneity and impaired extraction drive:

• ER–mitochondrial Ca²⁺ overlap [36],[37]
• Mitochondrial reactive oxygen species production [39]
• Thiol buffering strain and incomplete redox reset [39]

Skeletal muscle is uniquely vulnerable to this transition because:

• Contractile proteins and Ca²⁺ channels are cysteine-rich [39],[82]
• SERCA and ryanodine receptors are redox-sensitive [39]
• Mitochondrial density is high [30],[33]
• Perfusion variability is maximal [30],[31]

Under repeated stress, frequency-driven overlap shifts redox buffering from transient adaptation toward incomplete reversal. The tissue becomes primed for duration-based stabilization.

Mental and Autonomic Stress as Convergent Amplifiers

Physical exertion is not the sole trigger of PEM. Cognitive load, emotional stress, orthostatic challenge, and vigilance demand can precipitate delayed worsening even without high metabolic workload.

This does not contradict the skeletal muscle framework.

Mental and autonomic stress amplify frequency instability rather than directly inducing chemical stabilization. Acute stress reduces baroreflex gain and increases arterial pressure variability [15],[22], producing:

• Increased oscillatory pressure amplitude
• Increased shear heterogeneity [25]
• Reduced phase-locking between shear and nitric oxide signaling [27],[28]
• Greater adrenergic and purinergic trigger variability [23]–[26]

Skeletal muscle, because of its high vascular compliance and recruitment dynamics, remains highly sensitive to these fluctuations [30],[31]. Even modest perfusion volatility can increase intracellular calcium pulse frequency and overlap probability [23]–[26].

Thus:
• Physical exertion amplifies overlap through maximal perfusion scaling [30]–[32].
• Mental/autonomic stress amplifies overlap through timing degradation [15],[22]–[26].

Both converge at the same recovery-termination interface.

PEM is therefore neither purely muscular nor purely autonomic. It reflects a termination-centered architecture in which multiple stress-entry vectors converge on skeletal muscle as the dominant frequency amplifier.

Recovery Encoding and Progressive Instability

Longitudinal biopsy and post-exertional studies demonstrate that skeletal muscle abnormalities worsen following PEM induction, including fiber atrophy, focal necrosis, and altered oxidative metabolism [35]. This indicates that PEM reflects recovery-phase injury encoding rather than perceptual amplification.

As sterol-mediated authorization failure stabilizes non-termination at the cellular level [57]–[63], oxygen extraction control deteriorates further [33],[34]. This produces a reinforcing sequence:
Impaired extraction → Increased recovery-phase redox pressure [39] → Greater thiol persistence [39] → Increased sterol engagement probability [50]–[53],[57]–[63] → Lower future shear tolerance

With progression, baseline perfusion control bandwidth narrows. Shear tolerance decreases. Eventually, orthostatic load or cognitive stress alone may suffice to re-trigger the cascade [15],[22].

This explains:
• Severe intolerance to minimal exertion
• Orthostatic-triggered PEM
• Cognitive-triggered delayed muscle weakness
without requiring new structural injury.

Structural Role of Skeletal Muscle

Skeletal muscle does not initiate disease. Autonomic bias [15],[22], endothelial instability [25], immune-duration dysregulation [40]–[53], and redox buffering capacity [39] define systemic vulnerability.

However, skeletal muscle is the execution surface where perfusion scaling demand is maximal and where frequency-driven instability becomes biologically encoded [30]–[35]. It is the tissue in which shear volatility is largest, oxygen extraction failure is most evident, and recovery-phase redox stress is most intense.

Skeletal muscle therefore functions as the dominant generator and amplifier of frequency instability within the unified recovery-termination architecture.

Having established autonomic mistuning as the upstream destabilizer [15],[22]–[26] and skeletal muscle as the principal frequency amplifier [30]–[35], the acquisition model can now be formalized at the level of intracellular termination geometry and chemical stabilization [57]–[63].

5. The Gate Hierarchy — Initiation as a Control Transition

The acquisition of ME/CFS is not a single molecular event but a staged loss of recovery control. Recovery termination becomes progressively destabilized before it becomes chemically fixed.

Post-exertional malaise reflects failure of recovery completion [1],[33],[34]. The Gate Hierarchy formalizes how that failure progresses from baseline vulnerability (Gate 0), to reversible overlap instability (Gate 1), to persistent membrane authorization failure (Gate 2).

Only Gate 2 defines acquisition.
Gates 0 and 1 modify probability.

5.1 Gate 0 — Termination Vulnerability

Domain: Timing robustness
Status: Predisposition, not pathology

Gate 0 reflects reduced precision of signal decay without structural stabilization. It represents a baseline asymmetry in recovery kinetics that increases susceptibility to overlap under stress.

Contributing features may include:

• Reduced baroreflex buffering and autonomic trigger variability [15],[22]
• Glucocorticoid-mediated duration bias [16]–[18]
• Altered interferon inducibility or checkpoint attenuation [40]–[45]
• Genetic termination bias affecting signaling robustness [19]–[21]
• Baseline metabolic–immune heterogeneity [9],[10]
• Age-associated MAM drift affecting calcium handling precision [85]

At Gate 0:

• Membrane renewal authorization remains intact [57],[58]
• Sterol-sensing engagement remains transient [57],[58]
• ER-associated degradation operates homeostatically [61]–[64]
• Membrane plasticity is preserved

Recovery remains fully reversible. Gate 0 increases susceptibility. It does not constitute disease.

5.2 Gate 1 — Reversible Mechanical Non-Closure

Domain: ER–MAM termination geometry
Status: Reversible instability

Under physical or autonomic stress, signaling frequency increases [15],[22]–[26]. When inter-pulse intervals fall below decay kinetics, recovery-phase termination becomes geometrically unstable.

Frequency-driven instability produces:

• Persistent ER–mitochondrial contact [36],[37],[65],[66]
• Incomplete intracellular Ca²⁺ decay [36],[37]
• Increased mitochondrial Ca²⁺ uptake [36]
• Localized radical flux at contact interfaces [39]

This is a timing failure, not structural degeneration.

At Gate 1:

• Lipid-reset authorization remains intact [57],[58]
• INSIG occupancy decays between cycles [57],[58]
• SREBP trafficking resumes [57],[58]
• Membrane renewal remains permitted [57]–[63]

Overlap instability increases the probability of chemical stabilization but remains reversible.

At the organismal level, this corresponds to heightened PEM susceptibility without fixed phase transition [1],[33].

5.3 Gate 2 — Sterol-Mediated Lipid-Reset Authorization Failure

Domain: Endoplasmic reticulum sterol-sensing control
Status: Acquisition threshold

Acquisition occurs when sterol-sensing engagement persists across recovery cycles sufficiently to prevent reauthorization of membrane renewal.

Sterol engagement may arise through two non-exclusive mechanisms:

A. Duration-Amplified Immune Signaling

Prolonged interferon–STAT1 activation
→ CH25H induction [40],[50]
→ Increased 25-hydroxycholesterol production [50],[51]
→ Stabilization of INSIG via oxysterol binding [58]

B. Sterol Flux Imbalance

Accumulation of sterol intermediates (e.g., desmosterol)
→ Direct sterol-sensing engagement [60]

Persistent INSIG engagement produces coordinated enforcement:

• SCAP retention in the ER [57],[58]
• Blockade of SREBP transport and cleavage [57],[58]
• Recruitment of sterol-responsive ERAD ligases (RNF145, gp78, Hrd1) [61]–[63]
• Ubiquitination and degradation of HMG-CoA reductase [61]–[63]
• Contraction of membrane renewal bandwidth [57]–[63]

When renewal fails to resume, mechanical overlap becomes chemically stabilized.

Consequences include:

• Reduced cholesterol redistribution [57],[58]
• Reduced phospholipid remodeling [57]–[63]
• Increased membrane microdomain rigidity [69]
• Increased receptor dwell time [69],[73]
• Increased PLC retry probability
• Increased ER–MAM coupling gain [36],[65]

Redox–thiol persistence further increases sterol-engagement probability [39],[50]–[53].

This is the acquisition hinge.

Persistence Criterion — Kinetics Over Magnitude

Acquisition is defined by persistence, not sterol concentration.

The decisive condition is:
Sterol engagement remains elevated longer than lipid-reset recovery capacity across successive cycles [57]–[63].

If sterol engagement decays between cycles, termination remains reversible.
If engagement persists and prevents reauthorization, mechanical instability transitions into stabilized non-closure.

This is the phase transition.

Aging and Vascular Context (Relevance, Not Redefinition)

Aging biology independently identifies:

• MAM instability and impaired calcium precision [85]
• THBS1-driven vascular inflammaging and redox persistence [87]
• SREBP2 dysregulation as a hallmark of aging liver [88]

These findings support sterol regulation and MAM precision as resilience determinants.

However, in ME/CFS the proposed failure mode is not constitutive SREBP2 hyperactivation, but failure of sterol reset during recovery windows.

This distinction preserves the hinge: reset failure, not chronic overexpression.

Structural Definition of Initiation

Termination vulnerability [15]–[18],[19]–[21]
→ Reversible mechanical non-closure [36],[37],[39]
→ Persistent sterol-mediated lipid-reset suppression [57]–[63]

The transition from reversible overlap instability to sustained authorization failure defines ME/CFS acquisition.

Evidence Level and Falsifiability

Well established in sterol biology:

• INSIG-mediated SREBP retention [57],[58]
• Sterol-responsive ERAD degradation of HMG-CoA reductase [61]–[63]
• 25-hydroxycholesterol as a high-affinity sterol ligand [50],[51]
• Radical coupling chemistry at ER–MAM interfaces [28],[29],[39]

Predicted but not yet directly demonstrated in ME/CFS:

• Stress-window–linked ERAD bias
• Sustained INSIG occupancy during PEM
• Dynamic sterol kinetics across recovery cycles

INSIG persistence is proposed as a measurable biomarker.

Failure to demonstrate recovery-phase SREBP suppression during PEM would invalidate the acquisition hinge.

6. Loop A — Autonomic–Shear Termination Instability

Frequency-Driven Overlap Amplification

Definition

Autonomic–shear termination instability describes the process by which stress-induced degradation of vascular control precision increases arterial pressure variability and shear heterogeneity, thereby amplifying ER–mitochondrial calcium overlap probability.

Loop A:
• Does not establish acquisition
• Increases recovery-phase overlap frequency
• Raises termination geometry pressure

The destabilizing variable is loss of baroreflex gain and flow-phase precision under stress [15],[22].

A0 — Autonomic Entry

Physical, cognitive, emotional, or orthostatic stress
→ Increased sympathetic drive
→ Reduced vagal buffering
→ Central nitric oxide modulation within baroreflex circuits [15],[22]
→ Suppression of baroreflex gain

Reduced baroreflex gain increases both amplitude and frequency of arterial pressure oscillations [15],[22]. Perfusion becomes temporally unstable before any intracellular chemical stabilization occurs.

This is the initiating frequency disturbance.

Arm 1 — Pressure–Shear Instability

Reduced baroreflex buffering
→ Increased mean arterial pressure variability [15],[22]
→ Oscillatory flow amplification
→ Microvascular flow heterogeneity [25]
→ Local velocity spikes and shear gradients [25],[30],[31]

Shear transitions from coherent laminar signaling to spatially heterogeneous mechanical stress [25]. Skeletal muscle, with its extreme perfusion scaling range [30],[31], becomes the dominant frequency amplifier.

Arm 2 — THBS1–Glycocalyx–Mechanotransduction Amplification

Shear heterogeneity induces endothelial stress.

In ME/CFS, plasma proteomics demonstrate elevated THBS1 and altered endothelial protein signatures [93], consistent with vascular remodeling under disturbed flow.

Two parallel amplifiers emerge:

Parallel Amplifier A — THBS1 → CD47 → NO Suppression

THBS1 ↑
→ CD47 activation
→ Reduced NO–cGMP signaling
→ Impaired vasodilatory phase-locking
→ Increased shear heterogeneity

THBS1-driven signaling has been shown to promote interferon activation and mitochondrial ROS production in aging models [87], linking endothelial stress to redox vulnerability.

This represents degradation of signaling precision, not nitric oxide deficiency [27],[28].

Parallel Amplifier B — Glycocalyx / HS Damage

Oscillatory shear + ROS
→ Heparanase activation and HS fragmentation [91]
→ Glycocalyx thinning / patchiness
→ Loss of shear filtering
→ Focal membrane tension spikes

HS-binding proteins regulate coagulation and immune signaling [92], and HS structural drift has been demonstrated in aging tissues [89].

Glycocalyx perturbation therefore alters:

• Near-wall velocity gradients
• Receptor clustering (CD36/CD47/integrins)
• Lipoprotein docking heterogeneity
• Membrane cholesterol distribution topology

HS functions as a mechanical and topological filter. When damaged, membrane tension becomes noisier.

Convergence at Mechanotransduction

THBS1-mediated NO degradation
+
HS-mediated shear filtering loss
→ Membrane tension irregularity ↑
→ PIEZO1 activation timing noise ↑ [23],[25]
→ Irregular ATP release [23],[26]
→ Desynchronization of Gαq/Gαs signaling [23]–[26]
→ Increased intracellular Ca²⁺ pulse frequency [36],[37]

When:
Inter-pulse interval < decay kinetics
recovery-phase calcium signals overlap.

ER–mitochondrial contact persistence increases [36],[37],[65],[66]. Overlap probability rises.

Loop A therefore increases frequency pressure on recovery termination geometry.

Secondary Mechanical Amplifiers

Persistent shear heterogeneity may further produce:

• RBC deformability asymmetry [77]
• Hemoglobin-mediated nitric oxide scavenging variability [28],[29]
• Increased near-wall extracellular vesicle residence [75],[76]
• Clearance routing inefficiency [75],[76]

These amplify mechanical instability but do not establish chemical stabilization.

Functional Consequence

Autonomic–shear instability produces a state in which calcium pulse frequency approaches or exceeds decay capacity [36],[37].

Termination becomes geometrically unstable but remains chemically reversible:

• Membrane renewal authorization remains intact [57],[58]
• Sterol-sensing engagement remains transient [57],[58]

This state corresponds to heightened PEM susceptibility without phase transition [1],[33].

Loop A increases probability. It does not define disease.

Structural Role Within the Architecture

Loop A is the frequency amplifier of the acquisition architecture.

It integrates:

• Autonomic timing loss [15],[22]
• THBS1-mediated endothelial stress [87],[93]
• Glycocalyx degradation [91],[92]
• Mechanotransduction timing noise [23]–[26]

All converge on one outcome:
Increased recovery-phase Ca²⁺ overlap probability.

Chemical stabilization requires duration persistence and sterol-mediated authorization failure [57]–[63], addressed in Loop B.

Dual Reinforcement Framework

Autonomic–shear instability increases overlap frequency [15],[22]–[26].
Chemical stabilization lowers the overlap threshold [57]–[63].

Mechanical instability → increases duration pressure [39]–[41]
Chemical stabilization → increases mechanical sensitivity [69],[73]

This bidirectional coupling converts stress vulnerability into a self-reinforcing control-state failure.

7. Loop B — ER–MAM Redox–Sterol Stabilization

Duration-Driven Chemical Authorization Failure

Definition

ER–MAM redox–sterol stabilization describes the process by which frequency-driven calcium overlap becomes chemically fixed through persistence of sterol-mediated lipid-reset suppression.

Where Loop A increases overlap frequency [15],[22]–[26],
Loop B converts prolonged overlap into sustained membrane authorization failure [57]–[63].

Chemical stabilization requires duration persistence.

B0 — Ca²⁺ Duration Instability

When calcium pulse frequency exceeds decay capacity, recovery-phase signals begin to overlap [36],[37].

Repeated ER calcium release with incomplete restoration produces:

→ Persistent ER–mitochondrial contact [36],[65],[66]
→ Increased mitochondrial Ca²⁺ uptake [36],[37]
→ Prolonged intracellular Ca²⁺ duration
→ Sustained redox pressure at contact interfaces [39]

Calcium duration, not amplitude, becomes the destabilizing variable.

Prolonged duration drives two convergent processes.

Arm 1 — Redox–Thiol Sensitization

(Scaffold Sensitivity Amplifier)

Elevated mitochondrial Ca²⁺ flux
→ Increased superoxide generation [39]
→ NO + O₂•⁻ → peroxynitrite [28],[29]
→ Secondary oxidant formation (CO₃•⁻, NO₂) [29]

These oxidants:

→ Modify cysteine residues [28]
→ Promote glutathionylation and disulfide formation [39]
→ Increase intracellular disulfide burden [39]

Under sufficient NO flux, N₂O₃ formation permits thiol nitrosation [28],[84].

If calcium pulses recur before thiol restoration completes:

→ Incomplete reversal of thiol modifications [39]
→ Progressive thiol non-reset
→ Increased conformational sensitivity of sterol-sensing complexes

This arm alters disengagement kinetics. It increases sterol-sensing sensitivity without directly supplying ligand.

Arm 2 — Immune Duration and Sterol Ligand Supply

(Ligand Amplifier)

Prolonged intracellular calcium signaling
→ Sustained NF-κB / interferon cross-talk [40]–[47]
→ Extended STAT1 activation windows [40],[41]

Prolonged STAT1 activity
→ Induction of cholesterol 25-hydroxylase [50]
→ Increased 25-hydroxycholesterol production [50],[51]

25-hydroxycholesterol is a high-affinity INSIG ligand [50],[51].

This arm increases ligand availability, not scaffold sensitivity.

Immune-duration dysregulation therefore acts as the primary duration amplifier in the stabilization process [40]–[53].

Additional Duration Amplifier — HS–Sterol Flux Noise

Loop A introduces endothelial stress via:

THBS1 upregulation and glycocalyx disruption [87],[93],[91],[92].

HS patchiness does not directly regulate SREBP. However, it alters extracellular sterol topology.

HS fragmentation and sulfation drift [89],[91]:

→ Increase lipoprotein retention heterogeneity
→ Create focal cholesterol accumulation gradients
→ Alter membrane cholesterol partitioning
→ Increase sterol flux variability toward ER

This produces sterol gradient noise, not steady hypercholesterolemia.

Under redox persistence conditions, sterol flux heterogeneity increases the probability that INSIG remains engaged across recovery cycles.

HS damage functions as a probability amplifier, not a hinge.

Convergence — Persistent Sterol Engagement

Thiol sensitization [39]
+ Sustained sterol ligand production [50],[51]
+ Sterol flux gradient noise (HS-mediated) [89],[91],[92]
→ Increased probability that INSIG remains engaged across recovery cycles [57],[58]
→ Elevated INSIG occupancy duty cycle

When sterol engagement persists beyond lipid-reset recovery capacity, termination becomes chemically unauthorized [57]–[63].

This marks acquisition.

Authorization Enforcement

Sustained INSIG engagement produces coordinated suppression:

Transcriptional blockade
→ SCAP retention in ER [57],[58]
→ Inhibition of SREBP transport and cleavage [57],[58]
→ Suppression of lipid-reset gene expression

Sterol-responsive degradation bias
→ Recruitment of RNF145 and gp78 [61]–[63]
→ Ubiquitination and degradation of HMG-CoA reductase [61]–[63]
→ Contraction of cholesterol and membrane remodeling throughput [57]–[63]

Membrane renewal bandwidth narrows.

Structural Reinforcement

Reduced renewal capacity
→ Persistence of ordered lipid microdomains [69]
→ Increased receptor dwell time [69],[73]
→ Increased PLC retry probability [73]
→ Increased ER–MAM coupling gain [36],[65]

The overlap threshold lowers. Frequency-driven instability now requires less trigger intensity. Mechanical non-closure becomes chemically stabilized.

Persistence Criterion

Chemical stabilization is defined by persistence, not magnitude.

If sterol engagement decays between recovery cycles, lipid-reset resumes and instability remains reversible [57],[58].

If engagement persists long enough to prevent reauthorization, mechanical overlap transitions into stabilized non-closure [57]–[63].

This persistence threshold defines the acquisition hinge.

Structural Role Within the Architecture

Loop A increases overlap frequency [15],[22]–[26].
Loop B increases duration persistence and sterol engagement probability [39]–[53].

HS disruption and THBS1 upregulation amplify duration pressure but do not define the hinge [87]–[92].

Frequency destabilization alone does not establish disease. Duration persistence converts instability into a self-reinforcing attractor.

8. Dual-Loop Synthesis

From Dynamic Instability to Stabilization Threshold

The acquisition architecture distinguishes dynamic destabilization from chemical stabilization, and separates signal frequency from signal duration.

The Gate hierarchy defines structural states of recovery integrity.
The two loops describe the forces that move the system between those states.

Gate 0 — Vulnerability Without Stabilization

Termination vulnerability reflects reduced robustness of decay kinetics and autonomic buffering [15]–[18],[19]–[21]. Subtle asymmetries in baroreflex precision or immune-duration regulation increase susceptibility to stress-induced overlap, but membrane authorization remains intact.

The system is biased toward instability but remains fully reversible.

Gate 1 — Mechanical Instability Without Chemical Fixation

Reversible mechanical non-closure reflects active expression of autonomic–shear instability [15],[22]–[26]. Increased arterial pressure variability and degraded mechanotransduction timing elevate ER–mitochondrial calcium pulse frequency [23]–[26],[36],[37]. Recovery-phase signals begin to overlap.

However:
Membrane lipid renewal remains authorized [57],[58].
Sterol engagement remains transient.
Chemical stabilization has not occurred.

Loop A increases frequency pressure [15],[22]–[26].

Loop B — Duration Pressure and Probability Amplification

When overlap recurs before full restoration, redox–thiol persistence [39] and immune-duration amplification [40]–[53] increase the probability that sterol-sensing engagement remains elevated across recovery cycles [57]–[63].

Loop B increases duration pressure.

Duration persistence does not define acquisition by itself.
It increases the likelihood that membrane renewal fails to reset.

Gate 2 — Stabilization of Instability

Sterol-mediated lipid-reset suppression corresponds to stabilization of this instability. Persistent INSIG engagement prevents membrane renewal [57],[58], lowers termination tolerance, and reduces resistance to future shear variability [57]–[63].

The system crosses from dynamic instability to structural non-termination.

Hierarchical Progression

Termination vulnerability
→ increases susceptibility to frequency instability [15]–[18]
Frequency instability
→ increases duration pressure [39]–[41]
Duration persistence
→ increases sterol-engagement probability [50]–[53]
Persistent sterol engagement
→ stabilizes non-closure and lowers future overlap threshold [57]–[63]

Mechanical instability feeds chemical stabilization.
Chemical stabilization lowers the instability threshold.

In this coupled system, PEM reflects the dynamic expression of two destabilizing dimensions:

• Frequency amplification through autonomic–shear mistuning [15],[22]–[26]
• Duration persistence through redox–immune convergence [39]–[53]

The decisive question is not whether overlap occurs, but whether sterol-mediated reset fails to resume.

That phase transition is formalized below.

9. Sterol-Dependent Recovery Authorization Failure

Formal Phase Transition of Recovery Control

Recovery termination remains reversible as long as membrane lipid renewal authorization resumes between stress cycles [57],[58].

Define:

• Tf — intrinsic decay capacity of recovery signaling
• F — stress-induced pulse frequency
• D — sterol-engagement persistence duration
• R — lipid-reset recovery capacity

Mechanical Instability Condition

Mechanical instability emerges when:

F > Tf

Calcium pulses begin to overlap before full decay [36],[37].

However, instability remains mechanically reversible as long as membrane authorization resets between cycles [57],[58].

Chemical Stabilization Condition

Disease acquisition occurs only when:

D > R

Sterol engagement persists longer than renewal capacity allows.

When sterol-sensing engagement remains elevated across successive recovery cycles:

• SCAP-mediated SREBP transport fails to resume [57],[58]
• Sterol-responsive ER-associated degradation biases HMG-CoA reductase turnover [61]–[63]
• Cholesterol and phospholipid renewal bandwidth contracts [57]–[63]

At this threshold, reversible overlap instability transitions into chemically stabilized non-closure.

This transition constitutes Sterol-Dependent Recovery Authorization Failure.

What This Transition Does Not Require

It does not require:

• Systemic hypercholesterolemia
• Persistent infection
• Constitutive cytokine escalation
• Primary mitochondrial collapse

It requires only that sterol-sensing engagement persist beyond the system’s capacity to reset membrane renewal [57]–[63].

If sterol engagement decays between cycles, termination remains reversible [57],[58].

If engagement persists and prevents reauthorization, the system enters a stabilized control state.

Acquisition is therefore defined not by signal amplitude, but by failure of membrane renewal to reset between recovery windows.

Post-Hinge Clarification

Gate 2 establishes acquisition.
It does not complete the disease architecture.

Once lipid-reset authorization is suppressed, execution-surface remodeling begins immediately [69]–[73], altering membrane geometry and lowering the threshold for future overlap.

Stabilization deepens persistence without redefining the hinge.

10. Parallel Initiation Pathways: Ligand Duration vs Scaffold Sensitization

Duration Amplification and Authorization Probability

The recovery–termination architecture distinguishes two mechanistic domains:

• Immune-duration regulation (signal persistence)
• Membrane-authorization control (lipid-reset permission)

These operate in distinct compartments and fail by different mechanisms.

STAT1 governs transcriptional duration [40],[41].
Sterol-sensing machinery governs membrane renewal authorization [57],[58].

Only sustained sterol-dependent suppression of lipid-reset authorization defines acquisition [57]–[63].
Duration modifies probability.
Authorization failure stabilizes disease.

10.1 Ligand Duration — STAT1 as Persistence Amplifier

STAT1 is activated downstream of interferon signaling:
IFNAR → JAK → pSTAT1/STAT2 → ISGF3 → interferon-stimulated genes [40],[41].

Under physiological conditions, checkpoint regulators (SOCS, USP18, ubiquitin-editing systems) constrain activation duration rather than baseline amplitude [42]–[49]. Duration dysregulation can therefore occur without constitutive interferon elevation [40],[41].

Prolonged STAT1 activation extends induction windows for two sterol-relevant outputs:

• CH25H → 25-hydroxycholesterol (25-HC) production [50],[51]
• ACOD1 (IRG1) → itaconate production [54]–[56]

STAT1 therefore influences:

• Immune-duration persistence [40]–[53]
• Sterol-ligand availability [50],[51]
• Metabolic execution constraint [54]–[56]

STAT1 does not alter sterol-sensing scaffolds directly. It increases the probability that sterol engagement persists.

10.2 Path A — Sterol Ligand Amplification

Prolonged STAT1 activation
→ Sustained CH25H expression [50]
→ Increased 25-HC production [50],[51]

25-HC is a high-affinity INSIG ligand that stabilizes SCAP retention and suppresses SREBP transport [58].

If 25-HC decays between recovery cycles:
→ SREBP transport resumes
→ Membrane renewal resets [57],[58]
→ Stabilization does not occur

If ligand availability persists long enough:
→ INSIG occupancy duty cycle increases [58]
→ Membrane renewal remains suppressed [57]–[63]
→ Stabilization threshold is approached

Path A increases authorization probability.
It does not define acquisition.

10.3 Parallel STAT1 Output — IRG1 / Itaconate (Execution Constraint)

In parallel, STAT1 induces ACOD1 (IRG1), producing itaconate [54]–[56]. Itaconate competitively inhibits succinate dehydrogenase (complex II), reshaping mitochondrial redox topology [54],[55].

Consequences:

• Constrained TCA throughput [54]
• Altered redox bandwidth [54]–[56]
• Modified ROS dynamics [54]–[56]
• Increased energetic cost of recovery

Itaconate does not directly regulate sterol sensing.
It reduces recovery bandwidth, increasing the likelihood that redox persistence remains unresolved.

Execution constraint modifies restoration capacity, not authorization state.

10.4 Path B — Scaffold Sensitization (Ligand-Independent Engagement)

Sterol engagement can also be amplified independently of interferon duration.

Calcium-duration instability and redox pressure can:

• Modify thiol-dependent scaffold proteins [39],[28]
• Alter sterol disengagement kinetics
• Increase INSIG residence time [57],[58]

Sterol intermediates such as desmosterol may also contribute under flux imbalance [60]. Ligand supply and scaffold sensitivity are mechanistically distinct.

Persistent sterol engagement requires:

• Adequate ligand availability [50],[51]
• Impaired disengagement kinetics [39]

Neither alone defines acquisition.

10.5 HS–THBS1 Amplification and Sterol Flux Noise

Loop A introduces endothelial stress through:

• THBS1 upregulation [87],[93]
• Glycocalyx HS disruption [89]–[92]

HS patchiness does not directly regulate SREBP.

However, HS structural drift alters extracellular sterol topology:

HS fragmentation and sulfation variability [89],[91]
→ Heterogeneous lipoprotein retention
→ Local cholesterol accumulation gradients
→ Altered membrane cholesterol partitioning
→ Increased sterol flux variability toward ER

This produces sterol gradient noise rather than steady hypercholesterolemia.

Under redox persistence conditions, sterol flux heterogeneity increases the probability that INSIG engagement persists across recovery cycles.

HS–THBS1 signaling acts as a probability amplifier, not a hinge.

10.6 Convergence — Probability vs Authorization

Calcium-duration instability drives three amplifiers:

STAT1-mediated sterol ligand production [40]–[53]
Redox–thiol sensitization [39]
HS–THBS1–mediated sterol flux noise [87]–[92],[93]

All increase the probability of persistent sterol engagement.

However: Persistent sterol-sensing engagement across recovery cycles — not duration dysregulation alone — defines acquisition [57]–[63].

Duration and flux modify probability.
Authorization failure stabilizes disease.

10.7 Execution Constraint Feedback

Although itaconate does not directly suppress SREBP transport, mitochondrial redox reshaping may:

• Slow thiol restoration kinetics [39]
• Prolong redox pressure at ER–MAM interfaces [36],[39]
• Increase sterol-engagement persistence probability [50]–[53]

This is threshold modulation.

It shifts the stabilization boundary.
It does not initiate acquisition.

10.8 Canonical Distinction

Immune-duration persistence increases sterol ligand supply [40]–[53].
Redox–thiol sensitization alters disengagement kinetics [39].
HS–THBS1 signaling increases sterol flux variability [87]–[92],[93].
Execution constraint reduces recovery bandwidth [54]–[56].

Only sustained sterol-dependent suppression of membrane renewal defines acquisition [57]–[63].

10.9 From Authorization Lock to Execution Embedding

(Bridge to Section 11)

Once sterol-mediated authorization failure is established (Gate 2) [57]–[63], membrane renewal bandwidth contracts.

This does not simply suppress transcription. It alters:

• Lipid flux
• Sterol partitioning
• Phospholipid routing
• Membrane order [69]

Execution surfaces remodel under constrained renewal conditions [68]–[73]. These structural changes modify ER–MAM contact-site geometry [36],[65] and reduce Ca²⁺ termination fidelity.

Post-acquisition remodeling feeds back into Gate 1 dynamics, lowering re-trigger threshold without redefining the hinge [69],[73]. Section 11 formalizes how this embedding deepens persistence.

11. Post-Acquisition Persistence Architecture

Embedding, Amplification, and Maintenance

(Aligned to numbering 1–92)

Once sterol-dependent recovery authorization failure is established (Gate 2) [57]–[63], acquisition has occurred. Membrane renewal remains suppressed and recovery termination becomes chemically unauthorized.

The following layers do not initiate disease. They determine:

Stability
Severity
Reversibility
Phase progression

If sterol-dependent authorization failure establishes the attractor [57]–[63], these layers determine its depth and rigidity.

11.1 Gate 3 — Execution-Surface Embedding

Structural Remodeling and Termination Threshold Lowering

Following authorization failure, membrane renewal bandwidth contracts [57]–[63]. This does not cause immediate structural collapse; instead, it progressively reshapes membrane geometry under constrained lipid supply.

The system shifts toward:

Lipid accumulation and altered saturation balance [69]
PTDSS1-driven phosphatidylserine routing pressure [69]
Increased microdomain rigidity [69]
Altered raft clustering and receptor dwell time [69],[73]
Increased ER–MAM contact-site persistence [36],[65]

Execution surfaces remodel under renewal constraint [68]–[73]. This remodeling alters termination geometry.

Gate 3 does not initiate acquisition. However, by altering membrane order and ER–MAM microdomain organization [36],[65],[69], it increases the probability that subsequent Ca²⁺ pulses overlap before decay completes.

Thus, Gate 3 feeds directly back into Gate 1 dynamics [36],[37]. Termination becomes easier to re-trigger even when upstream signal amplitude is modest.

This is structural embedding of instability.

SMPDL3B as an Execution-Surface Readout

Altered anchoring and cleavage of GPI-anchored proteins such as SMPDL3B reflect degradation of execution precision [73].

Under renewal constraint:

PI-PLC–mediated cleavage thresholds may fall (shedding-dominant expression) [73]
Anchoring density may decline (deficient-dominant expression) [73]
Microdomain localization may drift [69],[73]

These changes are downstream manifestations of membrane renewal suppression [57]–[63].

They serve as measurable biomarkers of persistence, not drivers of acquisition.

Sex-Biased Expression (Execution Geometry Modifier)

Sex-specific lipid environments may bias execution-surface behavior without modifying the acquisition hinge [70].

PE-constrained, lower HexCer environments bias toward dynamic overshoot and shedding-dominant expression [70].
Saturation-enriched, HexCer-stabilized environments bias toward rigid, renewal-limited deficient expression [69],[70].

Sex modifies execution geometry at Gate 3 [70].
Gate 2 remains sex-neutral [57]–[63].
Severity reflects control collapse, not sex.

11.2 Gate 4 — Routing and Shear Amplification

Mechanical and Topological Persistence

Gate 3 remodeling increases extracellular and vascular burden:

Immature extracellular vesicles [67],[72]
Membrane fragments
Oxidized lipid species [39]
Procoagulant cargo [12]

Under healthy conditions, clearance depends on macrophage capacity and flow-dependent routing efficiency [75],[76].

In the acquired state:

Nitric oxide phase-locking remains degraded [27],[28]
Arterial pressure variability sustains shear heterogeneity [15],[22]–[26]
Microvascular transit becomes uneven [75]–[77]
Radical flux becomes spatially inconsistent [28],[39]

Clearance becomes topology-limited rather than purely capacity-limited [75],[76].

Microclots and fibrinaloid species function as topology amplifiers [12]. They do not initiate disease but increase endothelial stress and local activation when clearance efficiency declines.

RBC Deformability and Mechanical Inertia

Reduced red blood cell deformability introduces mechanical persistence [77]:

Impaired capillary transit increases flow heterogeneity
Shear gradients become irregular [25],[77]
Near-wall extracellular vesicle residence increases [75],[76]
Hemoglobin-mediated nitric oxide scavenging becomes spatially inconsistent [28]

Because erythrocytes lack transcriptional repair mechanisms, altered deformability persists across their lifespan [77].

Mechanical inertia lowers the threshold at which autonomic–shear instability re-expresses [15],[22]–[26].

Gate 4 amplifies instability. It does not define acquisition.

CNS Amplification — Not Acquisition

CNS-centered models describe sustained PVN dysfunction, microglial activation, or stress-axis maladaptation as drivers of persistence [7],[20].

Within this architecture, these phenomena are interpreted as downstream expressions of membrane-embedded non-closure rather than primary acquisition events.

Neuroinflammation is a persistence amplifier [7],[20].
It is not a biochemical authorization checkpoint [57]–[63].
The sterol-dependent hinge remains exclusive.

Adipose Duration Memory

Chronic stress exposure may induce sustained inflammatory and metabolic reprogramming within adipose depots [2],[4], reinforcing:

Immune-duration bias [40]–[53]
Endocrine amplification
Baseline repair demand

Adipose duration memory increases the probability of sterol re-engagement once authorization failure exists [2],[4].
It amplifies persistence.
It does not initiate acquisition.

11.3 Gate 5 — Maintenance Lock Layer

Rebuild Bandwidth Collapse

With persistent instability and suppressed renewal, rebuild demand exceeds recovery capacity.

This layer centers on regulatory instability within the NAD–SIRT1–c-Myc axis governing:

Membrane biosynthesis [78]–[80]
Mitochondrial biogenesis [78]–[81]
Anabolic restoration

NAD⁺ levels may remain measurable while regulatory engagement becomes insufficient [78]–[81].

Consequences include:

Reduced SIRT1 activation [78]–[80]
Destabilized c-Myc–dependent transcription [78]–[80]
Impaired lipid synthesis and membrane renewal [57]–[63],[78]–[80]

Sterol-dependent authorization failure maintains suppression [57]–[63].
Regulatory constraint reduces the capacity to reverse it [78]–[81].

The attractor deepens.

Phenotype Convergence Under Rebuild Constraint

Under sustained rebuild insufficiency:

Shedding-dominant phenotypes progressively lose anchoring stability [73]
Deficient phenotypes deepen structural insufficiency [69],[73]

Both converge toward:

Reduced execution precision
Lower recovery bandwidth
Increased rigidity of the acquired state

At this stage, modest autonomic–shear instability is sufficient to trigger severe PEM [15],[22]–[26].

Exit requires restoration of regulatory engagement and membrane rebuild capacity [78]–[81], not merely reduction of triggers.

Layered Synthesis

Sterol-dependent authorization failure establishes acquisition [57]–[63].

Execution-surface remodeling embeds instability and lowers re-trigger threshold [36],[65],[69]–[73].

Shear–buffering and routing amplification deepen mechanical persistence [12],[75]–[77].

Maintenance-layer constraint limits rebuild capacity [78]–[81].

Together, these layers explain:

Delayed PEM
Multi-system symptom propagation
Severity heterogeneity
Progressive narrowing of tolerance
Apparent irreversibility in advanced stages

Persistence is stabilized by control-layer erosion, shear amplification, redox–thiol persistence [39], buffering mismatch [75]–[77], and regulatory engagement failure [78]–[81] — not by ongoing infection.

12. ER–MAM Dynamics, Endothelial Aging, and Sterol Control Failure

A growing body of aging research identifies mitochondria–endoplasmic reticulum contact sites (MAMs) as central regulators of calcium transfer, lipid metabolism, ER stress signaling, and cellular stress adaptation [85]. Age-associated alterations in MAM integrity are linked to impaired mitochondrial calcium handling, increased oxidative stress, disrupted lipid trafficking, and reduced recovery capacity [85]. These features closely parallel the redox–thiol persistence arm of Loop B, in which repeated calcium overlap and incomplete thiol restoration increase the probability of sterol-sensing engagement [36],[39].

Thus, aging biology independently identifies ER–MAM precision as a determinant of resilience.

Endothelial Aging and THBS1 Amplification

Vascular aging is increasingly associated with elevated thrombospondin-1 (THBS1), an endothelial-derived matricellular protein that impairs nitric oxide signaling and limits regenerative recovery [87],[93]. Elevated THBS1 promotes perfusion heterogeneity, pro-thrombotic bias, and impaired stress resolution [87]. In aging models, endothelial THBS1 contributes to reduced hematopoietic recovery and persistent inflammatory tone [87], suggesting that it functions as a vascular phase-locking modifier that deepens stress persistence rather than initiating disease.

Within the present framework, THBS1 upregulation amplifies shear heterogeneity and redox pressure (Loop A), increasing the probability that ER–MAM calcium duration instability transitions into sterol engagement persistence (Loop B).

THBS1 therefore acts as an amplifier of duration pressure — not a sterol-reset hinge.

SREBP2 Hyperactivation in Aging vs Reset Failure in ME/CFS

Recent primate aging data demonstrate that hyperactivation of SREBP2 signaling is a hallmark of aged liver [88]. Forced SREBP2 activation in human hepatocytes induces senescence-like phenotypes and metabolic decline [88], establishing sterol regulatory programs as central drivers of aging-associated dysfunction.

However, the present model proposes a distinct but related failure mode in ME/CFS.

In aging:
→ SREBP2 is chronically overactivated at baseline [88].

In ME/CFS (proposed):
→ Sterol-regulated lipid-reset authorization fails to resume during recovery windows [57]–[63].
→ Persistent INSIG engagement prevents SCAP-mediated SREBP transport from reactivating after stress [57],[58].
→ The system fails to reset rather than remaining constitutively overactive.

This distinction is critical.
Aging reflects baseline sterol dysregulation.
ME/CFS acquisition reflects stress-window reset failure.

Empirical Implications

Aging studies typically assess steady-state sterol transcriptional programs at rest [88].

The recovery–termination architecture instead predicts that the decisive abnormality in ME/CFS will manifest during stress–recovery transitions:

• Persistence of sterol engagement during recovery windows [57]–[63]
• Failure of SREBP trafficking to resume post-stress [57],[58]
• Delayed lipid-reset reauthorization

The critical measurement is dynamic, not static.

The relevant question is not whether SREBP2 levels are high or low at rest, but whether sterol-sensing control returns to baseline after stress.

Future studies should prioritize:
• Post-exertional recovery sampling
• Stress-window ERAD activity
• INSIG occupancy kinetics
• SCAP–SREBP transport resumption timing

Failure to demonstrate stress-window sterol persistence would weaken the acquisition hinge.

Conceptual Integration

ME/CFS does not represent accelerated aging per se.

Rather, it reflects a stress-triggered collapse of sterol-regulated recovery precision at ER–MAM interfaces — a failure mode that aging biology independently identifies as central to declining cellular resilience [85].

In aging:
→ resilience declines gradually.
In ME/CFS (proposed):
→ stress triggers an abrupt reset failure.

Both converge on sterol-regulated recovery control.
Only the latter defines the acquisition hinge.

13. Testable Predictions and Falsifiability

The recovery–termination architecture proposes that:

• Acquisition occurs at sustained sterol-dependent membrane authorization failure (Gate 2).
• Persistence is deepened by execution-surface embedding (Gate 3), shear–buffering amplification (Gate 4), and regulatory engagement constraint (Gate 5).

The following predictions distinguish this model from alternative hypotheses and define empirically testable criteria.

13.1 Acquisition Biomarkers — Sterol-Dependent Authorization Failure

Prediction 1 — Recovery-Phase SREBP Suppression

During post-exertional malaise (PEM), patients should demonstrate:

• Reduced inducible nuclear SREBP2 cleavage during recovery windows
• Impaired ER→Golgi trafficking of SREBP
• Reduced transcription of lipid-reset targets (HMGCR, LDLR)
• Persistent SCAP–INSIG complex stabilization

Critically, this abnormality should appear during recovery, not necessarily at baseline.

Disconfirmation:
If SREBP transport and lipid-reset transcription remain intact during PEM, sterol-dependent authorization failure is unlikely to define acquisition [57]–[63].

Prediction 2 — Persistence, Not Magnitude

Disease severity and PEM duration should correlate with:

• Prolonged 25-hydroxycholesterol during stress windows [50],[51]
• Sustained INSIG engagement [57],[58]
• Stress-linked HMGCR degradation signatures [61]–[63]
• ERAD recruitment bias [61]–[63]

The decisive variable is engagement persistence, not peak sterol concentration.

Disconfirmation:
If sterol engagement does not track symptom dynamics, the acquisition hinge requires revision.

Prediction 3 — Authorization Precedes Embedding

Structural lipid remodeling must follow, not precede, sterol-reset suppression.

In early acquisition:

• Persistent SREBP suppression should temporally precede membrane-order changes [69],[73].

Disconfirmation:
If membrane remodeling occurs independently of sterol-reset suppression, the hinge lies upstream of sterol authorization.

13.2 Frequency–Duration Interaction

Prediction 4 — Frequency Before Fixation

In early or mild states:

• Increased arterial pressure variability [15],[22]
• Increased Ca²⁺ pulse frequency [23]–[26],[36],[37]
• Overlap probability increases without persistent SREBP suppression [57],[58]
• Lipid-reset authorization remains reversible [57],[58]

This confirms frequency destabilization preceding chemical stabilization.

Disconfirmation:
If frequency amplification alone directly produces irreversible membrane suppression, the two-stage acquisition model is weakened.

Prediction 5 — Duration Without Cytokine Storm

Patients should exhibit:

• Prolonged inducible STAT1 phosphorylation [40],[41]
• Sustained CH25H induction windows [50]
• Near-normal baseline interferon levels [40]
• Co-induction of ACOD1 and CH25H during stress [54]–[56]

This supports duration creep, not constitutive inflammation.

Disconfirmation:
If STAT1 kinetics are normal during stress challenges, the duration-amplification arm requires reassessment.

13.3 Execution Constraint and Feedback

Prediction 6 — Selective SDH Constraint

During stress windows:

• Increased succinate accumulation [54],[55]
• Selective complex II suppression [54],[55]
• Preserved complex I and IV respiration

This supports itaconate as an execution-layer modifier, not an acquisition hinge.

Disconfirmation:
If mitochondrial impairment is global, the execution-constraint framing must be revised.

Prediction 7 — Gate 3 Lowers the Threshold

In post-acquisition states:

• Ca²⁺ overlap probability increases at equivalent autonomic trigger frequency [36],[37]
• PLC re-trigger threshold decreases in membrane-order–shifted cells [69],[73]
• ER–MAM contact residence time increases [36],[65]

This tests Gate 3 feedback into termination geometry.

Disconfirmation:
If membrane remodeling does not alter Ca²⁺ termination fidelity, Gate 3 embedding requires revision.

Prediction 8 — Sex-Biased Termination Geometry

Under standardized stress:

Females should show:
• Higher Ca²⁺ event rate and overlap frequency
• Greater soluble-to-membrane SMPDL3B ratio [73]

Males should show:
• Longer Ca²⁺ residence times
• Reduced membrane-bound SMPDL3B without proportional soluble increase [73]

Disconfirmation:
If termination geometry does not differ by lipid background or sex, the execution-geometry model must be reconsidered.

13.4 Persistence-Layer Predictions

Prediction 9 — Trafficking Precision Loss Follows Authorization Failure

During PEM:

• Asynchronous glycosylation
• Partially processed EV cargo [67],[72]
• Altered GPI-anchor stability [73]

These changes should correlate with sterol-engagement persistence, not precede it.

Prediction 10 — Shear–Buffering Mismatch

Patients should demonstrate:

• Flow-dependent EV clearance variability [75],[76]
• Increased near-wall vesicle residence [75],[76]
• Reduced RBC deformability correlating with recovery duration [77]

Routing inefficiency should be flow-dependent, not purely macrophage-driven.

Prediction 11 — CNS as Amplifier, Not Hinge

If CNS inflammation is secondary:

• CNS inflammatory markers should correlate with sterol-engagement persistence [7],[20]
• Restoring membrane authorization should reduce CNS amplification even if baseline inflammatory tone remains detectable [57]–[63]

Disconfirmation:
If CNS stabilization precedes sterol-reset failure, hinge location must be reconsidered.

13.5 Maintenance-Layer Constraint

Prediction 12 — Regulatory Engagement Failure

Advanced states should demonstrate:

• Preserved or elevated NAD⁺
• Reduced SIRT1 activation [78]–[80]
• Destabilized c-Myc–dependent transcription [78]–[80]
• Impaired lipid biosynthesis despite substrate availability [57]–[63]

Maintenance pressure should correlate with delayed sterol disengagement kinetics.

13.6 Layer-Specific Intervention Logic

Interventions should produce layer-specific effects:

• Improving baroreflex precision reduces Ca²⁺ overlap frequency but does not restore SREBP transport [15],[22]–[26].
• Restoring membrane renewal normalizes SREBP transport even if immune tone persists [57]–[63].
• Improving shear routing reduces vesicle half-life without reversing sterol suppression [75],[76].
• Restoring regulatory engagement improves rebuild capacity before altering acquisition markers [78]–[81].

If interventions produce uniform, non-layered responses, the hierarchical architecture is unsupported.

Structural Falsifiability

The acquisition hinge collapses if:

• Recovery-phase SREBP transport remains intact during PEM
• INSIG persistence does not correlate with severity
• ERAD bias is absent during stress windows [61]–[63]
• Lipid remodeling precedes sterol-reset suppression
• CNS stabilization occurs independently of membrane authorization
• Gate 3 remodeling fails to alter Ca²⁺ fidelity [36],[65]
• Frequency destabilization does not precede chemical stabilization [15],[22]–[26]

Failure of these conditions would require reclassification of the model.

Predictive Structure Summary

The architecture predicts:

• Frequency amplification via autonomic–shear instability [15],[22]–[26]
• Duration amplification via STAT1 persistence [40]–[53]
• Selective SDH inhibition via itaconate [54]–[56]
• Sustained sterol-dependent membrane suppression [57]–[63]
• Execution-surface embedding that lowers re-trigger threshold [69],[73]
• Sex-biased termination geometry under distinct lipid backgrounds [70]
• Shear–buffering mismatch and routing limitation [75]–[77]
• Regulatory engagement constraint in advanced states [78]–[81]

These predictions provide measurable, falsifiable criteria for disease initiation, stabilization, and progression.

14. Limitations

The recovery–termination architecture is mechanistically integrated and internally coherent; however, several limitations must be acknowledged.

14.1 Lack of Direct In Vivo Demonstration of Authorization Persistence

Sterol-dependent suppression of SCAP–SREBP transport and sterol-responsive ER-associated degradation are well established in sterol biology. However, dynamic persistence of sterol-sensing engagement across recovery windows has not yet been directly demonstrated in ME/CFS patients in vivo.

The central acquisition claim — that membrane renewal authorization fails to resume during post-exertional recovery — remains an extrapolation from validated sterol regulatory mechanisms to a disease context in which real-time INSIG occupancy, SREBP trafficking, and ERAD recruitment have not yet been longitudinally measured during PEM.

The model is therefore biologically plausible but not yet dynamically verified.

14.2 Sterol-Ligand Kinetics During PEM

The framework emphasizes persistence of sterol engagement rather than sterol magnitude. Although 25-hydroxycholesterol is a high-affinity INSIG ligand, quantitative measurements of sterol-ligand kinetics during post-exertional recovery are lacking.

It remains unresolved whether:

CH25H induction is the dominant ligand source during PEM
Sterol flux imbalance contributes significantly in vivo
Local oxysterol production at ER–MAM interfaces reaches persistence thresholds required for stabilization

Direct measurement of sterol engagement dynamics during recovery windows is a critical experimental priority.

14.3 Thiol-State Persistence at ER–MAM Interfaces

The model assigns a central role to redox–thiol non-reset in altering sterol-sensing disengagement kinetics. While systemic redox imbalance has been reported in ME/CFS, sustained thiol-state persistence specifically localized to ER–mitochondrial contact sites during recovery has not been directly demonstrated.

It remains unclear whether thiol perturbation shifts sterol-sensing sensitivity causally or merely reflects parallel oxidative stress.

Thus, thiol persistence is mechanistically grounded but not yet spatially validated in vivo.

14.4 Gate 3 Feedback on Termination Geometry

The architecture proposes that post-acquisition membrane remodeling lowers Ca²⁺ termination fidelity and re-trigger threshold. Although lipid accumulation and phosphatidylserine shifts have been reported, direct demonstration that these changes measurably alter ER–MAM Ca²⁺ overlap kinetics in patients is lacking.

Establishing that structural embedding causally reduces termination threshold is necessary to validate the Gate 3 → Gate 1 feedback loop.

14.5 Temporal Separation of Frequency and Stabilization

The model separates frequency-driven overlap instability from duration-dependent chemical stabilization. Although autonomic variability and baroreflex impairment are documented, the quantitative relationship between arterial pressure variability, intracellular Ca²⁺ pulse frequency, and sterol-authorization persistence has not been directly established in humans.

Demonstrating that frequency amplification temporally precedes sterol-reset suppression requires simultaneous vascular, Ca²⁺, and sterol-regulatory measurements during controlled stress challenges.

Until such temporal resolution is obtained, ordering remains inferential.

14.6 ERAD Recruitment Bias During Recovery

The model predicts stress-window–linked recruitment of sterol-responsive E3 ligases (RNF145, gp78, Hrd1) to HMG-CoA reductase during PEM. While sterol-responsive ERAD is well characterized, its conditional engagement in ME/CFS has not been verified.

Demonstration of dynamic ERAD recruitment during recovery windows — rather than constitutive degradation — is essential to validate the acquisition hinge.

14.7 CNS Amplification vs Primary Acquisition

CNS-centered hypotheses propose PVN dysfunction or microglial activation as primary drivers. While compatible with this framework as persistence amplifiers, it remains possible that central mechanisms precede or influence membrane-authorization changes in some subsets.

Definitive exclusion of CNS-primary acquisition pathways requires simultaneous measurement of membrane authorization status and central inflammatory activity across early disease stages.

The sterol-dependent hinge is proposed as structurally decisive but cannot yet be considered exclusive.

14.8 Sex-Biased Execution Geometry

The model proposes sex-biased execution-surface geometry influencing phenotype expression. However:

Most lipidomic data are plasma-based rather than membrane-specific
Direct ER–MAM lipid composition measurements by sex are lacking
Ca²⁺ termination kinetics have not been stratified by sex in ME/CFS

Sex-biased expression remains a structured hypothesis requiring mechanistic confirmation.

14.9 Clinical Heterogeneity

ME/CFS is clinically heterogeneous. The framework attributes variability to differences in termination vulnerability, autonomic instability amplitude, duration amplification intensity, sterol-engagement persistence, buffering capacity, and rebuild bandwidth.

However, alternative acquisition pathways may exist in subsets. The sterol-dependent hinge may represent a dominant but not exclusive mechanism.

Stratified longitudinal validation is required.

14.10 Cross-Sectional Bias and Temporal Resolution

Most datasets remain cross-sectional. The proposed sequence — overlap instability → sterol persistence → layered amplification — requires longitudinal validation across pre-illness baseline, early illness, established disease, and progressive stages.

Without stress-window sampling, temporal causality cannot be definitively established.

14.11 Scope

This framework does not assert that sterol biology is the sole relevant pathway in ME/CFS. It proposes that sterol-dependent recovery authorization failure represents the structurally decisive phase transition converting reversible termination instability into a stabilized control state.

If future evidence demonstrates acquisition independent of membrane-authorization suppression, or shows execution-surface remodeling preceding sterol-reset failure, the hinge would require revision.

Limitation Summary

The recovery–termination architecture is mechanistically plausible and grounded in established sterol, redox, ERAD, and MAM biology. However, key elements remain experimentally unverified in ME/CFS, particularly:

Dynamic sterol-engagement persistence
Stress-window ERAD recruitment
ER–MAM thiol-state kinetics
Gate 3 feedback on Ca²⁺ termination fidelity
CNS-layer temporal ordering
Sex-stratified membrane composition
Longitudinal stress-window sequencing

Accordingly, the model is presented as a structured, falsifiable acquisition hypothesis rather than a confirmed causal pathway.

15. Therapeutic Intervention Logic

Control-Layer–Ordered Strategy

The recovery–termination architecture implies that durable therapeutic benefit requires alignment with the hierarchical structure of destabilization and stabilization. Acquisition and persistence arise from layered control failures. Interventions that do not respect layer order may transiently reduce symptoms but are unlikely to reverse structural non-termination.

Therapeutic strategy must therefore respect five domains:

Termination geometry (Gate 1)
Membrane authorization (Gate 2)
Execution-surface embedding (Gate 3)
Shear–buffering amplification (Gate 4)
Rebuild bandwidth (Gate 5)

Layer order determines sequence.
Probability reduction precedes authorization restoration.
Embedding correction follows hinge correction.
Rebuild restoration deepens reversibility.

15.1 Frequency Reduction Precedes Authorization Restoration

Autonomic–shear instability increases Ca²⁺ pulse frequency (Gate 1).
Sterol-dependent authorization failure stabilizes overlap (Gate 2).

Therefore:

Reducing overlap frequency lowers pressure on the stabilization threshold.
Restoring membrane renewal corrects the stabilized state.

Frequency reduction is protective.
Authorization restoration is corrective.

Interventions that modulate immune tone, increase mitochondrial throughput, or provide antioxidants without reducing shear-driven Ca²⁺ overlap may soften symptom expression but will not reverse acquisition.

Conversely, improving baroreflex precision or nitric oxide phase-locking reduces overlap probability but does not reverse sterol-reset suppression once stabilized.

This ordering is non-negotiable.

15.2 Layer-Specific Intervention Domains

1️⃣ Gate 1 — Termination Geometry Stabilization

Targets:
Autonomic precision, baroreflex gain, glycocalyx integrity, NO timing, Ca²⁺ overlap probability

Goal:
Reduce frequency of recovery-phase Ca²⁺ overlap

Domains may include:

Autonomic retraining
Orthostatic stabilization
Shear-variance reduction
Glycocalyx protection / HS preservation
NO phase-locking restoration

Glycocalyx integrity now becomes explicitly therapeutic:
Restoring HS structure improves shear filtering, reduces membrane tension noise, and stabilizes PIEZO1 timing fidelity.

Effect: lowers mechanical destabilization pressure.
Does not reverse acquisition if Gate 2 is engaged.

2️⃣ Gate 2 — Membrane Authorization Restoration (Acquisition Layer)

Targets:
INSIG persistence, SCAP–SREBP trafficking, ERAD bias, lipid-reset bandwidth

Goal:
Restore membrane renewal authorization

This is the hinge-corrective domain.

Potential strategies would aim to:

Normalize sterol-sensing disengagement
Restore SREBP transport after stress
Reduce stress-window ERAD over-recruitment
Improve lipid remodeling fidelity

Without restoration of membrane authorization, downstream embedding remains stabilized.

Gate 2 correction is necessary for structural reversal.

3️⃣ Gate 3 — Execution-Surface Embedding Correction

Gate 3 now explicitly includes:

Membrane cholesterol partitioning abnormalities
Microdomain rigidity
PTDSS1 / phosphatidylserine routing shifts
GPI-anchor instability
HS–membrane misalignment

Membrane depletion and sterol-reset failure increase ER repair demand while glycocalyx damage destabilizes membrane topology. This lowers Ca²⁺ termination fidelity and feeds back into Gate 1.

Targets:
Membrane order, lipid saturation balance, raft geometry, PS routing pressure, HS–membrane alignment

Goal:
Raise termination threshold and reduce re-trigger sensitivity

Effect:
Improves Ca²⁺ decay reliability and reduces PLC overshoot probability.
Reduces Gate 3 → Gate 1 feedback amplification.

Gate 3 correction deepens reversibility once authorization restoration has begun.

4️⃣ Gate 4 — Shear–Buffering and Routing Correction

Gate 4 now includes:

RBC deformability
Extracellular vesicle routing
Lipoprotein retention topology
HS patchiness
THBS1-driven NO suppression

THBS1 and glycocalyx perturbation amplify shear heterogeneity but do not define acquisition.

Targets:
Hemorheology, EV clearance routing, lipoprotein docking heterogeneity, THBS1-mediated signaling bias

Goal:
Reduce mechanical persistence amplification

Critical constraint:
Clearance-modifying or hemorheologic interventions should follow stabilization of termination geometry.
Altering microvascular topology before Ca²⁺ fidelity improves risks increasing overlap instability.

Gate 4 is an amplifier layer — not a hinge.

5️⃣ Gate 5 — Maintenance Lock (Rebuild Bandwidth)

In advanced states, renewal suppression is compounded by regulatory engagement failure (NAD–SIRT1–c-Myc axis).

Targets:
Rebuild capacity, transcriptional engagement, lipid biosynthesis competence

Goal:
Restore recovery bandwidth

This layer does not initiate persistence.
It limits reversibility once stabilization is established.

Rebuild restoration is restorative — not protective.

15.3 Stage-Dependent Logic

Pre-acquisition (Gate 0/1 dominant):
Stabilizing termination geometry may prevent transition.

Early post-acquisition (Gate 2 engaged):
Membrane renewal restoration becomes necessary.

Embedded persistence (Gate 3–4 active):
Execution-surface correction and routing stabilization become required.

Advanced states (Gate 5 constrained):
Rebuild capacity must be restored before durable reversal is possible.

Thus:

Frequency reduction → protective
Authorization restoration → corrective
Embedding correction → threshold-raising
Routing correction → amplifier reduction
Rebuild restoration → restorative

Misaligned sequencing risks transient relief without structural recovery.

15.4 Why Global Anti-Inflammation Is Insufficient

Reducing immune amplitude does not guarantee restoration of sterol-reset authorization.

Increasing mitochondrial throughput without correcting membrane renewal may increase instability under constrained lipid supply.

Antioxidant therapy that lowers radical flux without correcting duration persistence may reduce symptom intensity but not restore termination integrity.

Suppression ≠ reset.

15.5 CNS-Targeted Interventions in Context

CNS-layer therapies may reduce persistence amplification.

However:

If membrane authorization remains suppressed, CNS modulation alone cannot reverse acquisition.

CNS operates as Gate 3–4 amplifier, not hinge.

15.6 Sex-Biased Execution Geometry

Sex-biased lipid environments may alter tolerance and sequencing sensitivity:

Overshoot-prone (shedding-dominant) states may require earlier geometry stabilization.
Renewal-limited (deficient-dominant) states may require earlier rebuild emphasis.

Sex modifies execution geometry.
It does not alter acquisition hierarchy.

15.7 Translational Framing

PEM reflects dual-loop expression:

Frequency-driven overlap (Loop A)
Duration-driven stabilization (Loop B)

Durable improvement requires:

Lowering overlap frequency
Restoring membrane authorization
Correcting embedding geometry
Reducing routing amplification
Restoring rebuild capacity

Addressing one layer shifts symptom intensity.
Addressing layers in sequence shifts attractor depth.

15.8 Hierarchical Summary

This framework does not prescribe specific therapies.
It defines the order in which control layers must be addressed.

The translational thesis is:

ME/CFS is not primarily an inflammatory excess disorder nor an energy deficiency disorder.
It is a disorder of failed recovery reset.

Therapy must therefore restore:

Termination fidelity
Sterol-reset authorization
Membrane geometry integrity
Shear-buffering precision
Rebuild bandwidth

Alignment with hierarchy determines durability.

16. Conclusion

Recovery Termination as the Unifying Control Failure in ME/CFS

Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) can be reframed as a disorder of failed recovery control rather than a collection of isolated immune, metabolic, or vascular abnormalities. At the physiological level, the illness reflects an inability to safely regulate blood flow and metabolic scaling during stress. Skeletal muscle—by virtue of its extreme perfusion range and oxygen-extraction demand—most reliably exposes this defect [30]–[34]. Instead of increasing perfusion and returning cleanly to baseline, the system enters a prolonged and destabilized recovery phase. Post-exertional malaise (PEM) is the clinical expression of this failed recovery completion.

The architecture developed here separates destabilization from stabilization and probability from persistence. Autonomic–shear mistuning increases signaling frequency [15],[22]–[26]. Immune-duration dysregulation and redox–thiol persistence increase signaling duration [39]–[53]. These orthogonal pressures converge at a sterol-regulated membrane renewal checkpoint within the endoplasmic reticulum [57]–[63]. When lipid-reset authorization fails to resume across recovery cycles, reversible overlap instability becomes chemically stabilized. Disease acquisition is defined by this transition.

Persistence does not require ongoing infection or continuous immune escalation. It emerges from layered reinforcement. Execution-surface remodeling embeds instability within membrane architecture and lowers the threshold for renewed calcium overlap [36],[65],[69]–[73]. Glycocalyx disruption and THBS1-mediated endothelial stress amplify shear heterogeneity and mechanotransduction noise [87]–[92], increasing frequency pressure without redefining the hinge. Shear–buffering mismatch and routing inefficiency deepen mechanical persistence [75]–[77]. Regulatory engagement failure constrains rebuild capacity [78]–[81]. Together, these layers increase rigidity while leaving the sterol-dependent authorization checkpoint as the structurally decisive transition.

This framework integrates vascular–autonomic models [1],[15], skeletal muscle oxygen-extraction findings [32]–[34], purinergic and interferon-duration signaling [2],[40], redox imbalance [39], membrane remodeling signatures [69],[73], hemorheologic observations [12],[77], and aging-related MAM biology [85] into a single hierarchical structure. Previously competing hypotheses are repositioned as layer-specific contributors within a unified recovery-centered control system.

The decisive claim remains falsifiable: if recovery-phase SREBP transport remains intact during PEM, or if sterol-sensing engagement does not persist across recovery cycles, the acquisition hinge collapses. Conversely, demonstration of stress-window–linked sterol-dependent authorization failure would establish a mechanistic bridge between perfusion instability and chronic stabilization.

In this formulation, ME/CFS is a failure of safe stress scaling encoded at the level of membrane renewal control. Skeletal muscle reveals the defect; sterol-dependent authorization failure locks it in. Recovery does not complete because authorization does not reset. Understanding and restoring that reset—while stabilizing perfusion precision, glycocalyx integrity, and rebuild capacity—defines the central translational challenge.

References

APA 7th Edition · Ordered by Architecture · Numbered [1–92]

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VI. Gate 1 — ER–MAM Overlap & Redox Context

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52. Humer, B., Berentschot, J. C., van Helden-Meeuwsen, C. G., et al. (2025). Exaggerated IFN-I response in long COVID PBMCs following exposure to viral mimics. Journal of Clinical Immunology, 46(1), 5. https://doi.org/10.1007/s10875-025-01969-w
53. Eaton-Fitch, N., Rudd, P., Er, T., Hool, L., Herrero, L., & Marshall-Gradisnik, S. (2024). Immune exhaustion in ME/CFS and long COVID. JCI Insight, 9(20), e183810. https://doi.org/10.1172/jci.insight.183810

VIII. Itaconate / ACOD1 (IRG1) and SDH inhibition (Execution Constraint Layer)

54. Lampropoulou, V., Sergushichev, A., Bambouskova, M., et al. (2016). Itaconate links inhibition of succinate dehydrogenase with macrophage metabolic remodeling and regulation of inflammation. Cell Metabolism, 24(1), 158–166. https://doi.org/10.1016/j.cmet.2016.06.004
55. Cordes, T., Wallace, M., Michelucci, A., et al. (2016). Immunoresponsive gene 1 and itaconate inhibit succinate dehydrogenase to modulate intracellular succinate levels. Journal of Biological Chemistry, 291(27), 14274–14284. https://doi.org/10.1074/jbc.M115.685792
56. Peace, C. G., & O’Neill, L. A. (2022). The role of itaconate in host defense and inflammation. Journal of Clinical Investigation, 132(2), e148548. https://doi.org/10.1172/JCI148548

IX. Gate 2 — Sterol-Sensing Hinge and ERAD Enforcement (core sterol biology)

57. Brown, M. S., & Goldstein, J. L. (1997). The SREBP pathway: Regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor. Cell, 89(3), 331–340. https://doi.org/10.1016/S0092-8674(00)80213-5
58. Radhakrishnan, A., Ikeda, Y., Kwon, H. J., Brown, M. S., & Goldstein, J. L. (2007). Sterol-regulated transport of SREBPs from endoplasmic reticulum to Golgi: Oxysterols block transport by binding to INSIG. Proceedings of the National Academy of Sciences, 104(16), 6511–6518. https://doi.org/10.1073/pnas.0700899104
59. Hotamisligil, G. S. (2010). Endoplasmic reticulum stress and the inflammatory basis of metabolic disease. Cell, 140(6), 900–917. https://doi.org/10.1016/j.cell.2010.02.034
60. Spann, N. J., et al. (2012). Regulated accumulation of desmosterol integrates macrophage lipid metabolism and inflammatory responses. Cell, 151(1), 138–152. https://doi.org/10.1016/j.cell.2012.06.054
61. Song, B. L., Sever, N., & DeBose-Boyd, R. A. (2005). Gp78, a membrane-anchored ubiquitin ligase, associates with Insig-1 and couples sterol-regulated ubiquitination to degradation of HMG CoA reductase. Molecular Cell, 19(6), 829–840. https://doi.org/10.1016/j.molcel.2005.08.009
62. Joshi, V., Upadhyay, A., Kumar, A., & Mishra, A. (2017). Gp78 E3 ubiquitin ligase: Essential functions and contributions in proteostasis. Frontiers in Cellular Neuroscience, 11, 259. https://doi.org/10.3389/fncel.2017.00259
63. Menzies, S. A., Volkmar, N., van den Boomen, D. J. H., Timms, R. T., Dickson, A. S., Nathan, J. A., & Lehner, P. J. (2018). The sterol-responsive RNF145 E3 ubiquitin ligase mediates the degradation of HMG-CoA reductase together with gp78 and Hrd1. eLife, 7, e40009. https://doi.org/10.7554/eLife.40009
64. Jeon, Y. J., & Ronai, Z. A. (2026). The role of ER-associated degradation and ER-phagy in health and disease. Signal Transduction and Targeted Therapy, 11, 7. https://doi.org/10.1038/s41392-025-02501-7
65. Bui, V., Santerre, M., Shcherbik, N., & Sawaya, B. E. (2026). Mitochondria-associated membranes (MAMs): Molecular organization, cellular functions, and their role in health and disease. FEBS Open Bio, 16, 11–24. https://doi.org/10.1002/2211-5463.70121
66. Area-Gomez, E., & Schon, E. A. (2017). On the pathogenesis of Alzheimer’s disease: The MAM hypothesis. The FASEB Journal, 31(3), 864–867. https://doi.org/10.1096/fj.201601309
67. Glass, K. A., Giloteaux, L., Zhang, S., & Hanson, M. R. (2025). Extracellular vesicle proteomics uncovers ER stress responses post-exercise. Clinical and Translational Medicine, 15, e70346. https://doi.org/10.1002/ctm2.70346

X. Gate 3 — Trafficking Precision Loss and SMPDL3B Readout (lipid maladaptive state)

68. Wang, B., Stanford, K. R., & Kundu, M. (2020). ER-to-Golgi trafficking and its implication in neurological diseases. Cells, 9(2), 408. https://doi.org/10.3390/cells9020408
69. Missailidis, D., et al. (2025). Multi-omics identifies lipid accumulation and ether-phosphatidylcholine depletion in ME/CFS. Journal of Translational Medicine, 23, 620. https://doi.org/10.1186/s12967-025-07620-x
70. Nkiliza, A., Parks, M., Cseresznye, A., et al. (2021). Sex-specific plasma lipid profiles in ME/CFS. Journal of Translational Medicine, 19(1), 370. https://doi.org/10.1186/s12967-021-03035-6
71. Xiong, R., Aiken, E., Caldwell, R., Vernon, S. D., Kozhaya, L., Gunter, C., Bateman, L., Unutmaz, D., & Oh, J. (2025). AI-driven multi-omics modeling of myalgic encephalomyelitis/chronic fatigue syndrome. Nature Medicine, 31(9), 2991–3001. https://doi.org/10.1038/s41591-025-03788-3
72. Giloteaux, L., Glass, K. A., Germain, A., Franconi, C. J., Zhang, S., & Hanson, M. R. (2024). Dysregulation of extracellular vesicle protein cargo in female ME/CFS cases in response to maximal exercise. Journal of Extracellular Vesicles, 13(1), e12403. https://doi.org/10.1002/jev2.12403
73. Rostami-Afshari, B., Elremaly, W., Franco, A., Elbakry, M., Akoume, M. Y., Boufaied, I., Moezzi, A., Leveau, C., Rompré, P., Godbout, C., Mella, O., Fluge, Ø., & Moreau, A. (2025). SMPDL3B: A novel biomarker and therapeutic target in myalgic encephalomyelitis. Journal of Translational Medicine, 23(1), 748.

XI. Gate 4 — Clearance Routing Mismatch and Hemorheologic Amplification

74. Pesqueira Sanchez, M. A., de Necochea Campion, R., Dalhuisen, T., et al. (2025). Increased mannosylation of extracellular vesicles in long COVID plasma provides a potential therapeutic target for Galanthus nivalis agglutinin (GNA) affinity resin. bioRxiv (Preprint). https://doi.org/10.1101/2025.11.21.689519
75. Willekens, F. L. A., et al. (2005). Liver Kupffer cells rapidly remove red blood cell–derived vesicles from circulation by scavenger receptors. Blood, 105(5), 2141–2145. https://doi.org/10.1182/blood-2004-04-1578
76. Pavlova, S., Mamand, D. R., Hagey, D. W., et al. (2026). Injected extracellular vesicles hitchhike on erythrocytes and platelets toward organ clearance. Extracellular Vesicle, 7, 100103. https://doi.org/10.1016/j.vesic.2025.100103
77. Saha, A. K., Schmidt, B. R., Wilhelmy, J., Nguyen, V., Abugherir, A., Do, J. K., Nemat-Gorgani, M., Davis, R. W., & Ramasubramanian, A. K. (2019). Red blood cell deformability is diminished in patients with chronic fatigue syndrome. Clinical Hemorheology and Microcirculation, 71(1), 113–116. https://doi.org/10.3233/CH-180469

XII. Gate 5 — Maintenance Lock Layer (NAD–SIRT1–c-Myc axis; rebuild constraint)

78. Yuan, J., Minter-Dykhouse, K., & Lou, Z. (2009). A c-Myc–SIRT1 feedback loop regulates cell growth and transformation. The Journal of Cell Biology, 185(2), 203–211. https://doi.org/10.1083/jcb.200809167
79. Fan, W., Tang, S., Fan, X., et al. (2021). SIRT1 regulates sphingolipid metabolism and neural differentiation through c-Myc–SMPDL3B. eLife, 10, e67452. https://doi.org/10.7554/eLife.67452
80. Fan, W., & Li, X. (2023). The SIRT1–c-Myc axis in regulation of stem cells. Frontiers in Cell and Developmental Biology, 11, 1236968. https://doi.org/10.3389/fcell.2023.1236968
81. Saharan, S., Jhaveri, D. J., & Bartlett, P. F. (2013). SIRT1 regulates the neurogenic potential of neural precursors. Journal of Neuroscience Research, 91(5), 642–659. https://doi.org/10.1002/jnr.23199

XIII. Thiol Trapping & NO Timing Layer (additional biochemical supports)

82. Vellecco, V., et al. (2018). Hydrogen sulfide pathway and skeletal muscle: An introductory review. British Journal of Pharmacology, 175, 2213–2228. https://doi.org/10.1111/bph.14259
83. Hou, Y., Lv, B., Du, J., Ye, M., Jin, H., Yi, Y., & Huang, Y. (2025). Sulfide regulation and catabolism in health and disease. Signal Transduction and Targeted Therapy, 10, 174. https://doi.org/10.1038/s41392-025-02231-w
84. Ignarro, L. J. (1996). Physiology and pathophysiology of nitric oxide. Kidney International Supplement, 55, S2–S5.

XIV. Aging Dynamics, Glycocalyx, and Sterol Context

85. Monaghan, R. M. (2025). Mitochondria-associated membranes in ageing and disease. Open Biology, 14, 240287. https://doi.org/10.1098/rsob.240287
86. Hu, H., Ma, J., Peng, Y., Feng, R., Luo, C., Zhang, M., Tao, Z., Chen, L., Zhang, T., Chen, W., Yin, Q., Zhai, J., Chen, J., Yin, A., Wang, C. C., & Zhong, M. (2024). Thrombospondin-1 regulates trophoblast necroptosis via NEDD4-mediated ubiquitination of TAK1 in preeclampsia. Advanced Science, 11(21), e2309002. https://doi.org/10.1002/advs.202309002
87. Ramalingam, P., Gutkin, M. C., Poulos, M. G., Winiarski, A., Smith, A., Carter, C., Doughty, C., Tillery, T., Redmond, D., Freire, A. G., & Butler, J. M. (2025). Suppression of thrombospondin-1-mediated inflammaging prolongs hematopoietic health span. Science Immunology, 10(103), eads1556. https://doi.org/10.1126/sciimmunol.ads1556
88. Yang, X., et al. (2024). Single-nucleus transcriptomic and proteomic profiling identifies SREBP2-driven lipogenic activation as a hallmark of primate liver aging. Protein & Cell. https://doi.org/10.1093/procel/pwad039
89. Keenan, T. D., Pickford, C. E., Holley, R. J., Clark, S. J., Lin, W., Dowsey, A. W., Merry, C. L., Day, A. J., & Bishop, P. N. (2014). Age-dependent changes in heparan sulfate in human Bruch's membrane: Implications for age-related macular degeneration. Investigative Ophthalmology & Visual Science, 55(8), 5370–5379. https://doi.org/10.1167/iovs.14-14126
90. Kalafatis, E. (2017, September). Sulfation revisited: DHEA and syndecans. Algogenomics. https://algogenomics.blogspot.com/2017/09/sulfation-revisited-dhea-and-syndecans.html
91. Shu, J., & Santulli, G. (2019). Heparanase in health and disease: The neglected housekeeper of the cell? Atherosclerosis, 283, 124–126. https://doi.org/10.1016/j.atherosclerosis.2019.01.017
92. Gandy, L. A., Zhang, F., Xu, D., Pedersen, L. C., Grobe, K., & Wang, C. (2024). Editorial: Heparan sulfate-binding proteins in health and disease. Frontiers in Molecular Biosciences, 11, 1386623. https://doi.org/10.3389/fmolb.2024.1386623

93. Heng, B., Gunasegaran, B., Krishnamurthy, S., Bustamante, S., Pires, A. S., Chow, S., Ahn, S. B., Paul-Heng, M., Maciver, Y., Smith, K., Tran, D. P., Howley, P. P., Bilgin, A. A., Sharland, A., Schloeffel, R., & Guillemin, G. J. (2025). Mapping the complexity of ME/CFS: Evidence for abnormal energy metabolism, altered immune profile, and vascular dysfunction. Cell Reports Medicine, 6(12), 102514. https://doi.org/10.1016/j.xcrm.2025.102514