Tag: PEM
Inactivation of ATG13 stimulates chronic demyelinating pathologies in muscle-serving nerves and spinal cord
Abstract:
Chronic muscle fatigue is a condition characterized by debilitating muscle weakness and pain. Based on our recent finding to study the potential effect of mTOR on ATG13 inactivation in chronic muscle fatigue, we report that biweekly oral administration with MHY1485, a potent inducer of mTOR, develops chronic illness in mice resulting in severe muscle weakness. As a mechanism, we observed that MHY1485 feeding impaired ATG13-dependent autophagy, caused the infiltration of inflammatory M1 macrophages (Mφ), upregulated IL6 and RANTES by STAT3 activation, and augmented demyelination in muscle-serving nerve fibers. Interestingly, these mice displayed worsened muscle fatigue during 2-day post-treadmill exercise, suggesting the critical role of chronic mTOR activation in potential PEM pathogenesis. Interestingly, ATG13-repressor mice exhibited enhanced infiltration of M1Mφ cells, STAT3 activation, demyelination of nerve fibers, and PEM-like symptoms, suggesting the potential role of ATG13 impairment in post-exertional fatigue.
HIGHLIGHTS: The potential role of mTOR activation in post-exertional fatigue is highlighted. As a molecular mechanism, mTOR activation augments autophagy impairment via ATG13 inactivation. Autophagy impairment induces IL-6 and RANTES via STAT3, demyelinates nerves in the muscle and spinal cord. ATG13 repressor mice (Tg-ATG13) displayed inflammatory demyelination and post-treadmill fatigue.
Source: Drosen ME, Bulbule S, Gottschalk G, Peterson D, Allen LA, Arnold LA, Roy A. Inactivation of ATG13 stimulates chronic demyelinating pathologies in muscle-serving nerves and spinal cord. Immunol Res. 2025 Jan 7;73(1):27. doi: 10.1007/s12026-024-09557-7. PMID: 39777574. https://link.springer.com/article/10.1007/s12026-024-09557-7 (Full text)
Key Pathophysiological Role of Skeletal Muscle Disturbance in Post COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Accumulated Evidence
Abstract:
Background: Recent studies provide strong evidence for a key role of skeletal muscle pathophysiology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In a 2021 review article on the pathophysiology of ME/CFS, we postulated that hypoperfusion and ischemia can result in excessive sodium and calcium overload in skeletal muscles of ME/CFS patients to cause mitochondrial damage. Since then, experimental evidence has been provided that supports this concept.
Methods: We collect, summarize and discuss the current state of knowledge for the key role of skeletal muscle pathophysiology. We try to explain which risk factors and mechanisms are responsible for a subgroup of patients with post COVID syndrome (PCS) to develop ME/CFS (PC-ME/CFS).
Results: Mitochondrial dysfunction is a long-held assumption to explain cardinal symptoms of ME/CFS. However, mitochondrial dysfunction could not be convincingly shown in leukocytes. By contrast, recent studies provide strong evidence for mitochondrial dysfunction in skeletal muscle tissue in ME/CFS. An electron microscopy study could directly show damage of mitochondria in skeletal muscle of ME/CFS patients with a preferential subsarcolemmal localization but not in PCS. Another study shows signs of skeletal muscle damage and regeneration in biopsies taken one day after exercise in PC-ME/CFS. The simultaneous presence of necroses and signs of regeneration supports the concept of repeated damage. Other studies correlated diminished hand grip strength (HGS) with symptom severity and prognosis. A MRI study showed that intracellular sodium in muscles of ME/CFS patients is elevated and that levels correlate inversely with HGS. This finding corroborates our concept of sodium and consecutive calcium overload as cause of muscular and mitochondrial damage caused by enhanced proton-sodium exchange due to anaerobic metabolism and diminished activity of the sodium-potassium-ATPase. The histological investigations in ME/CFS exclude ischemia by microvascular obstruction, viral presence or immune myositis. The only known exercise-induced mechanism of damage left is sodium induced calcium overload. If ionic disturbance and mitochondrial dysfunction is severe enough the patient may be captured in a vicious circle. This energy deficit is the most likely cause of exertional intolerance and post exertional malaise and is further aggravated by exertion.
Conclusion: Based on this pathomechanism, future treatment approaches should focus on normalizing the cause of ionic disbalance. Current treatment strategies targeting hypoperfusion have the potential to improve the dysfunction of ion transporters.
Source: Scheibenbogen C, Wirth KJ. Key Pathophysiological Role of Skeletal Muscle Disturbance in Post COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Accumulated Evidence. J Cachexia Sarcopenia Muscle. 2025 Feb;16(1):e13669. doi: 10.1002/jcsm.13669. PMID: 39727052; PMCID: PMC11671797. https://pmc.ncbi.nlm.nih.gov/articles/PMC11671797/ (Full text)
The effects of 3-month supplementation with synbiotic on patient-reported outcomes, exercise tolerance, and brain and muscle metabolism in adult patients with post-COVID-19 chronic fatigue syndrome (STOP-FATIGUE): a randomized Placebo-controlled clinical trial
Abstract:
Purpose: Considering the observed gastrointestinal issues linked to post-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), beneficially modulating the gut microbiota could offer a safe, cost-effective nutritional strategy. This trial aimed to evaluate the effects of medium-term synbiotic supplementation on patient-reported outcomes, exercise tolerance, and tissue metabolism in patients with post-COVID-19 ME/CFS.
Methods: Between September 2022 and December 2023, we investigated the impact of 3-month supplementation with a synbiotic mixture including L. rhamnosus DSM 32550, Humiome® L. plantarum DSM 34532, B. lactis DSM 32269, B. longum DSM 32946, fructooligosaccharides and zinc, on predetermined primary and secondary outcome measures in twenty six post-COVID-19 ME/CFS patients utilizing a parallel-group, randomized, placebo-controlled, double-blind design.
Results: Both the synbiotic and placebo intake resulted in a significant reduction in general fatigue after 3 months compared to the baseline values (P ≤ 0.05). This was accompanied by a significant interaction effect (time vs. treatment) for post-exercise malaise (P = 0.02), with synbiotic superior to placebo to attenuate post-exercise malaise. The synbiotic also demonstrated a significant advantage over placebo in increasing choline levels at the thalamus (P = 0.02), and creatine levels at left frontal white matter (P = 0.05) and left frontal grey matter (P = 0.04).
Conclusion: Taking the synbiotic mixture for three months improves tissue metabolism and mitigates clinical features of post-COVID-19 fatigue syndrome. The presented data show promise in addressing the widespread issue of ME/CFS following the COVID-19 pandemic; however, further validation is needed before endorsing the synbiotics within this clinical context. The study is registered at ClinicalTrials.gov (NCT06013072).
Source: Ranisavljev M, Stajer V, Todorovic N, Ostojic J, Cvejic JH, Steinert RE, Ostojic SM. The effects of 3-month supplementation with synbiotic on patient-reported outcomes, exercise tolerance, and brain and muscle metabolism in adult patients with post-COVID-19 chronic fatigue syndrome (STOP-FATIGUE): a randomized Placebo-controlled clinical trial. Eur J Nutr. 2024 Nov 26;64(1):28. doi: 10.1007/s00394-024-03546-0. PMID: 39592468. https://pubmed.ncbi.nlm.nih.gov/39592468/
Two-Day Cardiopulmonary Exercise Testing in Long COVID Post-Exertional Malaise Diagnosis
Abstract:
Background: Long COVID patients present with a myriad of symptoms that can include fatigue, exercise intolerance and post exertional malaise (PEM). Long COVID has been compared to other post viral syndromes, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), where a reduction in day 2 cardiopulmonary exercise test (CPET) performance of a two-day CPET protocol is suggested to be a result of PEM. We investigated cardiopulmonary and perceptual responses to a two-day CPET protocol in Long COVID patients.
Methods: 15 Long COVID patients [n=7 females; mean (SD) age: 53(11) yr; BMI = 32.2(8.5) kg/m2] performed a pulmonary function test and two ramp-incremental CPETs separated by 24hr. CPET variables included gas exchange threshold (GET), V̇O2peak and WRpeak. Ratings of perceived dyspnoea and leg effort were recorded at peak exercise using the modified 0-10 Borg Scale. PEM (past six months) was assessed using the modified DePaul Symptom Questionnaire (mDSQ). One-sample t-tests were used to test significance of mean difference between days (p<0.05).
Results: mDSQ revealed PEM in 80% of patients. Lung function was normal. Responses to day 1 CPET were consistent with the presence of aerobic deconditioning in 40% of patients (V̇O2peak <80% predicted, in the absence of evidence of cardiovascular and pulmonary limitations). There were no differences between day-1 and day-2 CPET responses (all p>0.05).
Conclusion: Post exertional malaise symptoms in Long COVID patients, in the absence of differences in two-day CPET responses separated by 24hours, suggests that post-exertional malaise is not due to impaired recovery of exercise capacity between days.
Source: Gattoni C, Abbasi A, Ferguson C, Lanks CW, Decato TW, Rossiter HB, Casaburi R, Stringer WW. Two-Day Cardiopulmonary Exercise Testing in Long COVID Post-Exertional Malaise Diagnosis. Respir Physiol Neurobiol. 2024 Oct 25:104362. doi: 10.1016/j.resp.2024.104362. Epub ahead of print. PMID: 39490617. https://www.sciencedirect.com/science/article/pii/S1569904824001551 (Full text)
The persistence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) after SARS-CoV-2 infection: A systematic review and meta-analysis
Highlights:
- SARS-CoV-2 can trigger Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
- 51% of Long COVID-19 patients have Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
- Long COVID-19 is a new name for an old disease.
Abstract:
Objectives: Long COVID-19 (LC) patients experience a number of chronic idiopathic symptoms that are highly similar to those of post-viral Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). We have therefore performed a systematic review and meta-analysis to determine the proportion of LC patients that satisfy ME/CFS diagnostic criteria.
Methods: Clinical studies published between January 2020 to May 2023 were identified using the PubMed, Web of Science, Embase and CINAHL databases. Publication inclusion/exclusion criteria were formulated using the global CoCoPop framework. Data were pooled using a random-effects model with a restricted maximum-likelihood estimator. Study quality was assessed using the Joanna Briggs Institute critical assessment tool.
Results: We identified 13 eligible studies that reported a total of 1,973 LC patients. Our meta-analysis indicated that 51% (95% CI, 42%-60%) of LC patients satisfied ME/CFS diagnostic criteria with fatigue, sleep disruption, and muscle/joint pain being the most common symptoms. Importantly, LC patients also experienced the ME/CFS hallmark symptom, post-exertional malaise.
Conclusions: Our study not only demonstrates that LC patients exhibit similar symptom clusters to ME/CFS, but that approximately half of LC patients satisfy a diagnosis of ME/CFS. Our findings suggest that current ME/CFS criteria could be adapted to the identification of a subset of LC patients that may facilitate the standardized diagnosis, management and the recruitment for clinical studies in the future.
https://www.sciencedirect.com/science/article/pii/S0163445324002317 (Full text)
Towards an understanding of physical activity-induced post-exertional malaise: Insights into microvascular alterations and immunometabolic interactions in post-COVID condition and myalgic encephalomyelitis/chronic fatigue syndrome
Abstract:
Background: A considerable number of patients who contracted SARS-CoV-2 are affected by persistent multi-systemic symptoms, referred to as Post-COVID Condition (PCC). Post-exertional malaise (PEM) has been recognized as one of the most frequent manifestations of PCC and is a diagnostic criterion of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Yet, its underlying pathomechanisms remain poorly elucidated.
Purpose and methods: In this review, we describe current evidence indicating that key pathophysiological features of PCC and ME/CFS are involved in physical activity-induced PEM.
Results: Upon physical activity, affected patients exhibit a reduced systemic oxygen extraction and oxidative phosphorylation capacity. Accumulating evidence suggests that these are mediated by dysfunctions in mitochondrial capacities and microcirculation that are maintained by latent immune activation, conjointly impairing peripheral bioenergetics. Aggravating deficits in tissue perfusion and oxygen utilization during activities cause exertional intolerance that are frequently accompanied by tachycardia, dyspnea, early cessation of activity and elicit downstream metabolic effects. The accumulation of molecules such as lactate, reactive oxygen species or prostaglandins might trigger local and systemic immune activation. Subsequent intensification of bioenergetic inflexibilities, muscular ionic disturbances and modulation of central nervous system functions can lead to an exacerbation of existing pathologies and symptoms.
Source: Haunhorst S, Dudziak D, Scheibenbogen C, Seifert M, Sotzny F, Finke C, Behrends U, Aden K, Schreiber S, Brockmann D, Burggraf P, Bloch W, Ellert C, Ramoji A, Popp J, Reuken P, Walter M, Stallmach A, Puta C. Towards an understanding of physical activity-induced post-exertional malaise: Insights into microvascular alterations and immunometabolic interactions in post-COVID condition and myalgic encephalomyelitis/chronic fatigue syndrome. Infection. 2024 Sep 6. doi: 10.1007/s15010-024-02386-8. Epub ahead of print. PMID: 39240417. https://link.springer.com/article/10.1007/s15010-024-02386-8 (Full text)
Post-Exertional Malaise in Veterans with Gulf War Illness
Abstract:
Post-exertional malaise (PEM) is a potentially debilitating aspect of Gulf War Illness (GWI) that has received limited research attention. The purpose of the present investigation was to determine symptom severity changes following exercise in Veterans with GWI compared to control Veterans without GWI (CO).
Sixty-seven Veterans (n=39 GWI; n=28 CO) underwent a 30-minute submaximal exercise challenge at 70% of heart rate reserve. Symptom measurements (e.g. fatigue, pain) occurred pre-, immediately post-, and 24-hours post-exercise. Self-reported physical and mental health, and physiological and perceptual responses to exercise were compared between groups using descriptive statistics, independent samples t-tests and repeated measures Analysis of Variance (RM-ANOVA).
Post-exertional malaise was modeled using Group by Time (2 × 3) doubly-multivariate, RM-MANOVAs for (1) mood, (2) pain and (3) GWI-related symptoms, respectively (α=0.05). Data were analyzed for the full sample of Veterans with GWI (n=39) compared to CO (n=28) and a subsample of Veterans (n=18) who endorsed “feeling unwell after physical exercise or exertion” (“PEM endorsers”) during screening.
Veterans with GWI reported significantly lower physical and mental health. Groups exercised at similar relative exercise intensities, but GWI perceived exercise as more painful and fatiguing. Group-by-Time interactions were not significant for the entire sample for the three PEM models, however limiting the GWI sample to “PEM endorsers” resulted in significant interactions for Pain- and GWI-related PEM models.
These results indicate that not all GVs with GWI experience PEM 24 hr after exercise, and that more research is needed to determine the extent that exercise worsens symptoms in GWI.
Source: Lindheimer JB, Stegner AJ, Wylie GR, Klein-Adams JC, Almassi NE, Ninneman JV, Van Riper SM, Dougherty RJ, Falvo MJ, Cook DB. Post-exertional malaise in veterans with gulf war illness. Int J Psychophysiol. 2020 Jan;147:202-212. doi: 10.1016/j.ijpsycho.2019.11.008. Epub 2019 Nov 28. PMID: 31786249; PMCID: PMC6957714. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6957714/ (Full text)
Assessing Functional Capacity in Myalgic Encephalopathy/Chronic Fatigue Syndrome: A Patient-Informed Questionnaire
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Medical students highlight the importance of medical education, kindness, compassion and belief when learning about patients with myalgic encephalomyelitis/chronic fatigue syndrome
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