Emerging Hypotheses from 2025 Research
Recent multi-omics studies and clinical trials have revealed patterns that suggest several novel mechanistic hypotheses not previously considered.
1 The Vascular-Immune-Energy Triad
The Heng et al. 2025 study (Heng et al. 2025) identified a 7-biomarker diagnostic model spanning three systems: adenosine metabolism (AMP), immune markers (cDC1, LYVE1, IGHG2), and vascular factors (FN1, VWF, THBS1). This wasn’t three separate findings—it was one integrated signature. What if ME/CFS fundamentally involves a coordinated failure mode across these three systems that cannot be understood or treated in isolation?
The triad might work as follows:
- Energy failure (elevated AMP/ADP, reduced ATP) impairs immune cell maturation and function
- Immature immune cells (elevated na"ive B cells, reduced switched memory B cells, immature T cell subsets) fail to properly regulate vascular function and produce dysfunctional antibodies
- Vascular dysfunction (elevated VWF, fibronectin, thrombospondin) reduces tissue perfusion, causing cellular hypoxia that worsens energy production
This creates a stable triangular trap where each vertex reinforces the others. Treating only one system fails because the other two pull it back.
Therapeutic Implication. Effective treatment might require simultaneous intervention at all three vertices: NAD+ precursors for energy, immunomodulation for immune maturation, and vascular-targeted therapy (anticoagulation, endothelial support) for perfusion. The daratumumab success (60% response) might reflect cases where the autoimmune vertex was dominant—remove it, and the triad destabilizes enough to collapse.
2 The Plasma Cell Sanctuary Hypothesis
The daratumumab trial’s success—where targeting CD38+ plasma cells produced sustained remission in 60% of patients—reveals something important: rituximab (anti-CD20) failed in ME/CFS trials, yet daratumumab (anti-CD38) succeeded. Both deplete antibody-producing cells, but they target different populations.
B cells (CD20+) are the precursors; plasma cells (CD38+) are the factories. Crucially, long-lived plasma cells can survive for decades in bone marrow and gut niches, continuously secreting antibodies without needing B cell replenishment. What if ME/CFS is maintained by these “sanctuary” plasma cells?
Under this model:
- An initial trigger (infection) generates autoreactive B cells
- Some differentiate into long-lived plasma cells that migrate to survival niches
- These plasma cells produce autoantibodies (anti-GPCR, anti-ion channel) indefinitely
- Rituximab depletes B cells but not established plasma cells—antibody production continues
- By the time B cells return, the patient hasn’t improved, so the trial “fails”
- Daratumumab directly kills the plasma cell factories, stopping antibody production
This explains the 8–9 month delay before maximum daratumumab benefit: existing autoantibodies must decay (IgG half-life \(\sim\) 3 weeks, but tissue-bound antibodies persist longer).
Undocumented Phenomenon. If true, ME/CFS patients should have expanded populations of long-lived plasma cells in bone marrow biopsies, and these cells should be producing the pathogenic autoantibodies. This has never been directly examined.
Treatment Implication. Combining daratumumab (kill factories) with immunoadsorption (remove existing antibodies) might produce faster and more complete responses than either alone.
3 The Endothelial Activation Cascade
The Heng 2025 study (Heng et al. 2025) found elevated plasma proteins associated with “activation of the endothelium and remodeling of vessel walls.” Specifically: VWF (von Willebrand factor), FN1 (fibronectin), and THBS1 (thrombospondin-1). These aren’t random inflammatory markers—they suggest a specific pathology: chronic endothelial activation.
Endothelial cells line all blood vessels. When activated (by infection, inflammation, autoantibodies, or hypoxia), they:
- Release VWF, promoting platelet adhesion and microclotting
- Deposit fibronectin, contributing to vascular remodeling
- Express thrombospondin, which is anti-angiogenic and pro-fibrotic
- Become “leaky,” allowing inappropriate extravasation
- Lose their normal anti-inflammatory and vasodilatory functions
What if ME/CFS is fundamentally an endotheliopathy—a chronic disease of blood vessel lining? This would explain:
- Exercise intolerance: Dysfunctional endothelium cannot vasodilate properly to meet demand
- Brain fog: Cerebral microvascular dysfunction impairs cognition
- Orthostatic intolerance: Poor vascular tone regulation
- PEM: Exercise-induced endothelial stress takes days to resolve
- Multi-system involvement: Endothelium is everywhere
Connection to Long COVID. This hypothesis aligns with the “microclot” findings in Long COVID, where amyloid-fibrin microclots persist in circulation. ME/CFS might involve the same endothelial activation without necessarily forming detectable microclots.
Undocumented Phenomenon. Direct endothelial function testing (flow-mediated dilation, EndoPAT) in ME/CFS has been limited. Comprehensive endothelial biomarker panels and functional testing might reveal a consistent endotheliopathy signature.
Treatment Implication. If endothelial dysfunction is central:
- Endothelial-protective supplements (L-arginine, L-citrulline, beetroot/nitrates) might help
- Statins (pleiotropic endothelial benefits beyond cholesterol) might be beneficial
- Low-dose aspirin or other anti-platelet agents might reduce microclot burden
- ACE inhibitors (endothelial-protective independent of blood pressure) could be therapeutic
- HELP apheresis (removes fibrinogen and inflammatory mediators) might address both cause and consequence
4 The Dendritic Cell Maturation Block
The Heng 2025 study (Heng et al. 2025) found reduced CD1c+CD141- conventional dendritic cells type 2 (cDC2) and a general skewing toward “less mature” immune cell subsets across T cells, NK cells, and dendritic cells. This isn’t random immune dysfunction—it suggests a specific developmental block.
Dendritic cells are the “conductors” of the immune orchestra. They:
- Capture antigens and present them to T cells
- Determine whether immune responses are inflammatory or tolerogenic
- Bridge innate and adaptive immunity
- Mature in response to danger signals
What if ME/CFS involves a block in dendritic cell maturation? Immature DCs:
- Present antigens inefficiently
- Fail to properly activate T cells
- May promote tolerance when activation is needed (chronic infection persistence)
- May promote inflammation when tolerance is needed (autoimmunity)
The immune system would be simultaneously ineffective (can’t clear threats) and dysregulated (inappropriate responses). This dual failure could maintain chronic immune activation without resolution.
Why Maturation Might Be Blocked.
- Energy deficit: DC maturation is metabolically demanding; ATP shortage might arrest development
- Chronic antigen exposure: Persistent viral antigens or autoantibodies might cause “exhaustion”
- Cytokine milieu: Altered cytokine patterns might signal DCs to remain immature
- Epigenetic lock: Maturation genes might be epigenetically silenced
Treatment Implication. Therapies that promote DC maturation (GM-CSF, specific TLR agonists, DC-targeted vaccines) might help—but could also be dangerous if the DCs then activate against self-antigens. This is a double-edged sword requiring careful patient selection.
5 The NAD+ Depletion Spiral
Multiple findings converge on NAD+:
- Heng et al. (Heng et al. 2025): Abnormal NAD+ metabolism in ME/CFS immune cells
- The tryptophan-kynurenine pathway terminates in NAD+ synthesis
- PARP enzymes (activated by DNA damage/oxidative stress) consume NAD+
- Sirtuins (cellular stress response) require NAD+
- Mitochondrial Complex I requires NAD+/NADH cycling
What if NAD+ depletion is not just a consequence but a central driver—a bottleneck where multiple pathological processes converge?
The spiral might work as follows:
- Initial insult causes oxidative stress and DNA damage
- PARP enzymes activate to repair damage, consuming NAD+
- NAD+ depletion impairs mitochondrial function (Complex I requires NAD+)
- Mitochondrial dysfunction increases oxidative stress
- More oxidative stress → more PARP activation → more NAD+ depletion
- Meanwhile, inflammatory IDO activation shunts tryptophan away from serotonin toward kynurenine-NAD+ pathway—but the NAD+ produced may be immediately consumed by PARPs
- Sirtuins, starved of NAD+, cannot perform their protective functions (autophagy, mitophagy, epigenetic regulation)
- The cell enters a stable low-NAD+ state where it survives but cannot function normally
Undocumented Phenomenon. Direct measurement of NAD+/NADH ratios in ME/CFS patient tissues (not just blood) has been limited. If the spiral hypothesis is correct:
- Tissue NAD+ should be severely depleted
- PARP activity should be chronically elevated
- Sirtuin activity should be reduced
- The kynurenine pathway should be active but NAD+ still depleted (production consumed by PARPs)
Treatment Implication. NAD+ precursors (NR, NMN) alone might fail if PARPs immediately consume the new NAD+. Combination with PARP inhibitors (used in cancer) might be necessary—but PARP inhibition carries risks (impaired DNA repair). A gentler approach: high-dose NAD+ precursors to “flood” the system beyond PARP consumption capacity.
6 The Effort-Preference Recalibration
The Walitt 2024 NIH study made a crucial distinction: ME/CFS patients showed altered effort preference, not physical fatigue or central fatigue. Their muscles could produce force; their brain could generate motor commands. But when given choices, they systematically avoided effortful options even when rewards were high.
This isn’t laziness or depression—it’s a recalibration of the brain’s effort-reward computation. The brain has a system (involving the anterior cingulate cortex, insula, and dopaminergic circuits) that weighs expected effort against expected reward to decide whether actions are “worth it.”
What if ME/CFS involves a fundamental shift in this computation, such that:
- Effort is perceived as more costly than it actually is
- Rewards are perceived as less valuable than they would be
- The “break-even” point shifts dramatically toward rest
- This shift is protective (effort genuinely IS more costly due to metabolic dysfunction) but becomes miscalibrated
The CSF catecholamine deficiency found by Walitt et al. supports this: dopamine is central to effort-reward computation. Reduced central dopamine would systematically bias the system toward effort avoidance.
Why This Matters. If effort preference is centrally altered, then:
- “Pushing through” fights against an active brain computation, not just physical limits
- The system might be trainable but requires different approaches than physical reconditioning
- Dopaminergic interventions might help recalibrate the computation
- But if the recalibration is appropriate given metabolic dysfunction, forcing change could be harmful
Treatment Implication. Low-dose stimulants (methylphenidate, modafinil) might shift effort-reward computation—but could cause crashes if patients then overexert. The key might be: restore metabolic function FIRST, then (if needed) recalibrate effort perception.
7 The Immune Cell Energy Crisis
The Heng 2025 finding (Heng et al. 2025) of elevated AMP/ADP in white blood cells suggests immune cells specifically are energy-starved. This has profound implications because immune cells are metabolically unique:
- Na"ive T cells are metabolically quiescent
- Upon activation, T cells undergo massive metabolic reprogramming (Warburg effect)
- This reprogramming requires abundant ATP and NAD+
- If immune cells cannot meet energy demands, activation fails
- Failed activation = ineffective immune responses + potential for inappropriate responses
The pattern of “immature” immune cells in ME/CFS might not reflect a developmental block per se, but rather an energy crisis that prevents cells from completing their activation/maturation programs.
Consider: a T cell encounters its antigen and begins activation. Activation requires massive ATP expenditure. But the cell is already AMP/ADP-elevated, ATP-depleted. It cannot complete activation. It either:
- Dies (activation-induced cell death from energy failure)
- Becomes anergic (gives up on activation)
- Partially activates (creating dysfunctional effector cells)
Any of these outcomes would create the immune dysfunction pattern seen in ME/CFS.
Undocumented Phenomenon. The metabolic competence of ME/CFS immune cells during activation has not been thoroughly studied. Prediction: ME/CFS T cells stimulated in vitro should show impaired metabolic reprogramming (measured by Seahorse assay or similar).
Treatment Implication. Supporting immune cell metabolism specifically might help:
- NAD+ precursors might restore immune cell energy capacity
- Specific metabolites (pyruvate, \(\alpha\)-ketoglutarate) might bypass defective pathways
- Ketone bodies (which immune cells can use as fuel) might provide alternative energy
8 The Vascular “Memory” Hypothesis
Immune cells can be “trained”—epigenetically reprogrammed by past exposures to respond differently to future stimuli. This innate immune memory (distinct from adaptive immunity) has been demonstrated in monocytes, macrophages, and NK cells.
What if endothelial cells can also be “trained”—and what if ME/CFS involves maladaptive endothelial training?
Endothelial cells experience the initial infection/inflammation. They activate, express adhesion molecules, become pro-thrombotic. Normally they return to quiescence. But what if severe or prolonged activation creates epigenetic changes that lock them in a partially activated state?
This “trained endotheliopathy” would:
- Persist long after the original trigger resolves
- Be present throughout the vasculature (explaining multi-system symptoms)
- Respond excessively to normal stimuli (exercise, stress, infection)
- Be resistant to conventional anti-inflammatory treatment
- Potentially be reversible with epigenetic interventions
Undocumented Phenomenon. Epigenetic profiling of endothelial cells from ME/CFS patients has not been performed. Circulating endothelial cells or endothelial progenitor cells might show characteristic epigenetic signatures.
The hypotheses in this section derive largely from a single multi-omics study (Heng et al. 2025) and from reinterpretation of the NIH deep-phenotyping study (Walitt et al. 2024, n=17). Epistemic boundaries:
- The Heng 2025 biomarker model has not been independently validated; the 7-biomarker signature was derived from a single cohort and may not generalise to other ME/CFS populations or diagnostic criteria.
- The “vascular-immune-energy triad,” “NAD+ depletion spiral,” and “dendritic cell maturation block” are interpretive frameworks imposed on cross-sectional omics data—the data establish association, not the causal relationships depicted.
- The “effort-preference recalibration” hypothesis reinterprets the Walitt NIH study, which was itself controversial: the cohort was small (n=17 PI-ME/CFS), used contested inclusion criteria, and some findings (e.g., grip strength claims) were disputed by patient advocacy organisations and independent researchers.
- Treatment protocols proposed below (triple-target, plasma cell eradication, endothelial restoration) are speculative extrapolations from these early-stage findings; none has been tested even in pilot form.
9 Speculative Treatment Approaches from 2025 Findings
Based on the above hypotheses, several novel treatment approaches emerge:
9.1 The Triple-Target Protocol
If the vascular-immune-energy triad is the core mechanism, a protocol targeting all three simultaneously might produce synergistic effects:
- Energy: High-dose NAD+ precursor (NR 1000–2000 mg/day) plus mitochondrial cofactors (CoQ10, PQQ, B vitamins)
- Immune: Low-dose naltrexone (immune modulation) plus vitamin D optimization (immune regulation)
- Vascular: L-arginine/citrulline (endothelial NO production) plus low-dose aspirin (anti-platelet) plus omega-3 fatty acids (endothelial protection)
This combination is relatively safe and addresses all three triad vertices. The hypothesis predicts it should work better than any single intervention.
9.2 The Plasma Cell Eradication Strategy
For patients with evidence of autoimmunity (elevated anti-GPCR antibodies, post-infectious onset, dramatic response to immunoadsorption):
- Phase 1: Immunoadsorption series to remove circulating autoantibodies
- Phase 2: Daratumumab (or similar CD38-targeting agent) to eliminate plasma cell factories
- Phase 3: Monitor for autoantibody rebound; repeat if needed
- Phase 4: Once autoantibodies cleared, assess whether other “locks” need addressing
This aggressive approach would only be appropriate for patients with clear autoimmune features and access to specialized centers.
9.3 The Endothelial Restoration Protocol
If endotheliopathy is central, a vascular-focused protocol might help:
- Reduce endothelial activation: Statin therapy (pleiotropic endothelial effects)
- Support NO production: L-citrulline (better than L-arginine for sustained NO)
- Address microclots: Nattokinase (fibrinolytic enzyme) or low-dose anticoagulation if indicated
- Protect endothelium: Sulforaphane (Nrf2 activation), omega-3s, anthocyanins
- Reduce thrombotic tendency: Aspirin, adequate hydration, compression if tolerated
This approach treats ME/CFS as a vascular disease, which it may fundamentally be in at least a subset of patients.
10 The Evolutionary Deferred-Cost Hypothesis for PEM Timing
The characteristic 12–72 hour delay between exertion and post-exertional malaise (PEM) in ME/CFS is often treated as a disease-specific anomaly requiring special explanation. This speculation proposes instead that the delay is normal physiology — a deferred-cost architecture selected for over evolutionary time — and that ME/CFS is characterised not by an aberrant delay but by the failure of the restoration phase that was always supposed to follow it.
The evolutionary argument. Organisms whose physiology permitted emergency action — running, fighting, escaping — even when ill, injured, or energy-depleted were more likely to survive acute threats and reproduce. Organisms whose fatigue was an absolute limit at baseline capacity did not escape predators or survive combat. The deferred-cost architecture was therefore selected for: act first, pay later. The sequencing itself is adaptive.
This manifests in several well-characterised physiological systems:
Catecholamine-mediated override: Epinephrine and norepinephrine suppress pain (stress-induced analgesia, mediated by endogenous opioids and endocannabinoids (Parikh et al. 2011)), mobilise hepatic glycogen within seconds, and increase muscle fibre recruitment beyond voluntary maxima. The cost — glycogen depletion, lactic acidosis, oxidative stress — is deferred.
HPA axis mobilisation: Cortisol redirects energy from immune surveillance, digestion, and repair toward immediate locomotor and cognitive demands. The immune debt is paid through the post-stress immune rebound, which peaks hours after the stressor ends.
Human endurance physiology: Humans evolved fatigue-resistant slow-twitch musculature and exceptional heat dissipation capacity specifically to sustain locomotion under energetic stress (Bramble and Lieberman 2004) (Marino, Sibson, and Lieberman 2022). The capacity to continue moving while physiologically compromised was a critical survival advantage in persistence hunting and predator escape.
Sickness behaviour as the restoration phase: Hart (1988) described sickness behaviour — fatigue, anorexia, social withdrawal, sleep — as an adaptive programme that enforces rest and redirects metabolic resources toward immune function and repair (Hart 1988). Cytokines (IL-1\(\beta\), IL-6, TNF-\(\alpha\)) mediate this programme by acting on the hypothalamus (Dantzer and Kelley 2007). This is the “pay” phase of the deferred-cost cycle: the invoice the body sends after the emergency is resolved.
The delay between exertion and the onset of the sickness behaviour/repair response is not an accident. It is the normal timescale of the cytokine cascade: pro-inflammatory cytokines peak 6–24 hours post-exertion in ME/CFS patients at levels and durations not seen in healthy controls (Che et al. 2025). The debt is always deferred; in a healthy person, it is simply repaid within days.
Application to ME/CFS. The central claim of this speculation is: in ME/CFS, the emergency override mechanism is intact but the restoration mechanism is broken.
Evidence for intact override:
Most ME/CFS patients, even severely affected ones, retain some capacity for emergency mobilisation; only the most profoundly impaired cannot act at all.
A 2025 systematic review and meta-analysis found elevated baseline epinephrine levels and upregulated adrenergic receptor expression in ME/CFS (Hendrix et al. 2025), consistent with a chronically stress-activated adrenergic system.
The “wired but tired” phenomenon documented by patients — a state of sympathetic activation concurrent with profound functional exhaustion — reflects this dissociation: the mobilisation system is firing; the reserves it draws on are depleted.
Evidence for broken restoration:
Mitochondrial ATP resynthesis is impaired; cellular energy debt cannot be fully cleared between exertion episodes (two-day CPET studies document objective functional decline on day two).
The post-exertional immune response is pathologically amplified and prolonged: CXCL10, IL-8, CCL4, TNF-\(\beta\), and ICAM-1 are abnormally elevated specifically in ME/CFS 18 hours after submaximal exercise but not in matched sedentary controls (Moneghetti et al. 2018), representing a sickness behaviour programme that activates but cannot complete its repair function.
The glymphatic clearance that is supposed to operate during sickness-behaviour-enforced sleep is itself impaired by the fragmented, low-slow-wave sleep architecture of ME/CFS (see Glymphatic/CSF Clearance Failure).
Relationship to the “stuck sickness behaviour” hypothesis. This speculation is complementary to, but distinct from, the metabolic safe-mode hypothesis (Metabolic “Safe Mode” Hypothesis). That hypothesis proposes that the sickness behaviour programme is chronically engaged even at rest. This speculation adds a different dimension: that the emergency override system — which can temporarily suppress or bypass the sickness behaviour programme in response to acute threat — remains functional, producing the characteristic functional window during exertion. The crash that follows is not a new pathological event; it is the normal sickness behaviour programme reasserting itself, amplified and unresolvable due to the broken repair machinery.
Together, the two dynamics predict the canonical ME/CFS exertion pattern:
Baseline state: sickness behaviour programme engaged (fatigue, reduced function)
During exertion: emergency override partially suppresses symptoms (patient can act; cost is being borrowed)
12–72 hours post-exertion: sickness behaviour programme reinforced by the post-exertion cytokine cascade (the invoice arrives)
Recovery phase: in healthy physiology, restoration occurs and baseline returns; in ME/CFS, restoration is incomplete, baseline deteriorates
Why “you seemed fine” is not a contradiction. This framework resolves a persistent social misunderstanding. Observers who note that a person with ME/CFS was able to attend an event or complete a task conclude this is inconsistent with severe illness. But the override mechanism is precisely designed to permit action under compromised conditions. Functional capacity during exertion reflects emergency mobilisation, not available capacity. The cost is deferred, not avoided.
Severity gradient. The model predicts a severity gradient: in mild-to-moderate ME/CFS, the override is intact and the restoration is partial; in severe ME/CFS, chronic adrenergic activation and repeated overdraft deplete even the emergency reserves, progressively eroding the override capacity; in very severe ME/CFS, the system has nothing left to mobilise. This maps onto the observed clinical spectrum and suggests that disease progression may involve a progressive failure of the override mechanism itself, not merely a worsening of baseline function.
Testable predictions:
Adrenergic reserve capacity (e.g., epinephrine response to orthostatic stress or cognitive challenge) should be inversely correlated with disease severity and duration.
The functional window during exertion (time from beginning activity to symptom onset) should predict crash severity, reflecting the degree to which emergency override was engaged.
Blocking catecholamine signalling during exertion (e.g., \(\beta\)-blockade) should attenuate the subsequent crash if the override is driving the magnitude of the debt.
In very severe patients, catecholamine responses to acute stressors should be blunted relative to moderate patients.
(Certainty: Very low. Evolutionary-mechanistic synthesis; individual components are established, but the integrated framework has not been directly tested in ME/CFS.)
McCaddon and Regland propose that viral infections — including SARS-CoV-2 — initiate ME/CFS-like states through a “methyl-group assault”: simultaneous depletion of methyl-group availability (via viral RNA modification demands consuming SAM) and impairment of resupply (via oxidative inactivation of methionine synthase) (McCaddon and Regland 2021). The predicted biochemical consequence is elevated homocysteine and depleted SAM, impairing downstream methylation reactions and mitochondrial function.
The authors note that long-COVID fatigue (87%) and memory complaints (78%) overlap with pernicious anemia (a classical state of B12-mediated methylation failure) at strikingly similar rates (McCaddon and Regland 2021), and cite the CSF homocysteine elevation documented in CFS by Regland et al. (Regland et al. 1997) as consistent with this pathway.
Testable predictions: (1) Elevated CSF homocysteine should be detectable in post-viral ME/CFS patients acutely and persist chronically. (2) Serum and CSF SAM should be reduced in long-COVID/ME/CFS relative to controls. (3) Early B12/methylfolate supplementation post-viral illness should reduce ME/CFS onset risk (preventive trial).
Status: Unconfirmed hypothesis. Medical Hypotheses journal publishes speculative ideas without requiring primary empirical data. Requires prospective biomarker studies and interventional trials for validation.
(Certainty: Very low. Hypothesis only.)