Major Studies Summary

This section synthesizes key research findings integrated from literature reviews, including papers identified through systematic searches, community-reported studies, and recent publications (2019–2025).

1 Molecular and Cellular Mechanisms

Molecular Mechanism Studies in ME/CFS
Study	Design	Sample	Key Findings	Implications	Certainty
Wang 2023 (Wang et al. 2023)	Case-control; muscle biopsy	n=14 ME/CFS, n=10 controls	WASF3 protein elevated; inverse correlation with Complex IV (r=-0.55, p=0.005); shRNA knockdown restores function	WASF3 is druggable target; mechanism is reversible	MODERATE (pending replication)
Lim 2020 (Lim et al. 2020)	2-day CPET; repeated measures	n=51 ME/CFS, n=10 sedentary controls	VO₂max reduced 25% on Day 2 in ME/CFS; controls unchanged; ventilatory threshold reduced	Objective PEM biomarker; 24-72h delayed impairment	HIGH (replicated)
Syed 2025 (Syed et al. 2025)	Systematic review	Multiple studies	Mitochondrial dysfunction across oxidative phosphorylation, ATP synthesis, metabolomics	Converging evidence for mitochondrial pathology	MODERATE-HIGH (meta-analytic)
Phair 2019 (Phair, Davis, and Kashi 2019)	Metabolomics modeling	n=52 ME/CFS, n=45 controls	IDO metabolic trap hypothesis; tryptophan-kynurenine pathway disruption	Potential therapeutic target (IDO inhibitors)	MODERATE (hypothesis; needs validation)

2 Viral and Infectious Triggers

Viral Association Studies
Study	Design	Sample	Key Findings	Evidence Level
Hwang 2023 (Hwang et al. 2023)	Systematic review + meta-analysis	64 studies; n=4,971 ME/CFS, n=9,221 controls	18 viral species assessed; strongest associations: Borna (OR\(\geq\) 3.47), HHV-7 (OR>2.0), parvovirus B19 (OR>2.0), enterovirus (OR>2.0), coxsackie B (OR>2.0)	HIGH (meta-analytic; replicated)
Chia 2005 (Chia 2005)	Observational; stomach biopsy	n=165 ME/CFS patients	Enterovirus detected in 82% of ME/CFS patients via stomach biopsy immunostaining; correlation with symptom severity	MODERATE (specialized technique; replication needed)
Gottschalk 2023 (Gottschalk et al. 2023)	Case series; observational	n=42 Long COVID patients	LDN (4.5mg) improved fatigue, brain fog, PEM in 78% of Long COVID patients within 2 months	LOW-MODERATE (observational; no control group)

3 Immune Dysfunction Studies

Immune System Studies in ME/CFS
Study	Design	Sample	Key Findings	Certainty
Fluge 2019 (Fluge et al. 2019)	Phase III RCT (RituxME trial)	n=152 ME/CFS	Rituximab (B-cell depletion) showed NO benefit vs placebo; placebo response 35%, rituximab 26%	HIGH (definitive negative result)
Rekeland 2024 (Rekeland et al. 2024)	Long-term follow-up of RituxME	Original n=152 cohort; 6-year follow-up	No long-term benefit from rituximab confirmed; subset analysis revealed no responder subgroups	HIGH (confirms Fluge 2019)
Bulbule 2024 (Bulbule et al. 2024)	Systematic review	Multiple NK cell studies	Reduced NK cell cytotoxicity consistently reported across studies; correlation with symptom severity	MODERATE-HIGH (consistent finding)

References

Bulbule, Sarojini, Carl Gunnar Gottschalk, Molly E. Drosen, Daniel Peterson, Leggy A. Arnold, and Avik Roy. 2024. “Dysregulation of Tetrahydrobiopterin Metabolism in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome by Pentose Phosphate Pathway.” Journal of Central Nervous System Disease 16: 11795735241271675. https://doi.org/10.1177/11795735241271675.

Chia, John K. S. 2005. “The Role of Enterovirus in Chronic Fatigue Syndrome.” Journal of Clinical Pathology 58 (11): 1126–32. https://doi.org/10.1136/jcp.2004.020255.

Fluge, Øystein, Ingrid G. Rekeland, Kristin Lien, Hilde Thürmer, Petter C. Borchgrevink, Christoph Schäfer, Kari Sørland, et al. 2019. “B-Lymphocyte Depletion in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial.” Annals of Internal Medicine 170 (9): 585–93. https://doi.org/10.7326/M18-1451.

Gottschalk, Carl Gunnar, Ryan Whelan, Daniel Peterson, and Avik Roy. 2023. “Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study.” International Journal of Molecular Sciences 24 (10): 8713. https://doi.org/10.3390/ijms24108713.

Hwang, Jae-Hyun, Jae-Seung Lee, Hyun-Mi Oh, et al. 2023. “Evaluation of Viral Infection as an Etiology of ME/CFS: A Systematic Review and Meta-Analysis.” Journal of Translational Medicine 21 (1): 763. https://doi.org/10.1186/s12967-023-04635-0.

Lim, Eun-Jin, Eun-Bum Kang, Eun-Su Jang, and Chang-Gue Son. 2020. “Systematic Review of the Two-Day Cardiopulmonary Exercise Test as an Objective Assessment Tool for Post-Exertional Malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.” Journal of Clinical Medicine 9 (12): 4040. https://doi.org/10.3390/jcm9124040.

Phair, Robert D., Ronald W. Davis, and Alex A. Kashi. 2019. “The IDO Metabolic Trap Hypothesis for the Etiology of ME/CFS.” Diagnostics 9 (3): 82. https://doi.org/10.3390/diagnostics9030082.

Rekeland, Ingrid G., Kari Sørland, Linn L. Neteland, Alexander Fosså, Kari Alme, Kristin Risa, Olav Dahl, Karl J. Tronstad, Olav Mella, and Øystein Fluge. 2024. “Six-Year Follow-up of Participants in Two Clinical Trials of Rituximab or Cyclophosphamide in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.” PLoS One 19 (7): e0307484. https://doi.org/10.1371/journal.pone.0307484.

Syed, Abu Mohammad, Alexander K Karius, Jin Ma, Ping-yuan Wang, and Paul M Hwang. 2025. “Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.” Physiology 40 (4). https://doi.org/10.1152/physiol.00056.2024.

Wang, Ping-yuan, Jin Ma, Young-Chae Kim, et al. 2023. “WASF3 Disrupts Mitochondrial Respiration and May Mediate Exercise Intolerance in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.” Proceedings of the National Academy of Sciences 120 (34): e2302738120. https://doi.org/10.1073/pnas.2302738120.