Tag: PEM

Concentrations of uremic bacterial metabolites in patients with post-COVID-19 syndrome

Abstract:

Post-COVID-19 syndrome (PCS) is characterized by persistent symptoms and reduced mental and physical performance following the acute phase of COVID-19. The underlying mechanisms remain unclear but may involve gut microbiota dysbiosis and immune-related changes in amino acid metabolism. This pilot study aimed to investigate whether specific bacterial uremic metabolites (BUM) are altered in patients with post-infectious syndromes and whether these alterations are associated with PCS symptoms.

We examined BUM in 25 PCS patients, 8 Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) patients, and 8 healthy controls (Ctrls). Concentrations of BUM were determined in second morning urine samples using mass spectrometry (Biovis Diagnostik, Limburg, Germany). Standardized questionnaires assesed physical, cognitive, psychological, and somatic symptoms and mental health status.

PCS and ME/CFS patients exhibited significantly higher scores for post-exertional malaise (PEM) and somatic symptom severity compared to healthy controls (p<0.001). Elevated BUM concentrations were found in 64% of PCS patients, compared to 37.5% of both healthy controls and ME/CFS patients. While overall BUM levels did not significantly differ between groups, heatmap clustering revealed distinct metabolic patterns.

Elevated tryptamine and 4-hydroxyphenylpropionic acid (HPHPA) and higher hippuric acid and trimethylamine concentrations, were exclusively analysed in patients with post-infectious syndromes. Our pilot study suggests that urine metabolomic analysis may be a useful approach for investigating the role of gut dysbiosis and BUM in patients with PCS.

Source: Brigo N, Mayr W, Taenzer M, Löffler-Ragg J, Schroll A, Engl S, Schütz B, Rappl P, Heine T, Weiss G, Kurz K. Concentrations of uremic bacterial metabolites in patients with post-COVID-19 syndrome. Front Cell Infect Microbiol. 2025 May 29;15:1582972. doi: 10.3389/fcimb.2025.1582972. PMID: 40510799; PMCID: PMC12159039. https://pmc.ncbi.nlm.nih.gov/articles/PMC12159039/ (Full text)

Skeletal muscle properties in long COVID and ME/CFS differ from those induced by bed rest

Abstract:

Patients with long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) suffer from a reduced exercise capacity, skeletal muscle abnormalities and post-exertional malaise (PEM), where symptoms worsen with cognitive or physical exertion. PEM often results in avoidance of physical activity, resulting in a lower aerobic fitness, which may contribute to skeletal muscle abnormalities. Here, we compared whole-body exercise responses and skeletal muscle adaptations after strict 60-day bed rest in healthy people with those in patients with long COVID and ME/CFS, and healthy age- and sex-matched controls.

Bed rest altered the respiratory and cardiovascular responses to (sub)maximal exercise, while patients exhibited respiratory alterations only at submaximal exercise. Bed rest caused muscle atrophy, and the reduced oxidative phosphorylation related to reductions in maximal oxygen uptake.

Patients with long COVID and ME/CFS did not have muscle atrophy, but had less capillaries and a more glycolytic fibers, none of which were associated with maximal oxygen uptake. While the whole-body aerobic capacity is similar following bed rest compared to patients, the skeletal muscle characteristics differed, suggesting that physical inactivity alone does not explain the lower exercise capacity in long COVID and ME/CFS.

Source: Braeden T. Charlton, Anouk Slaghekke, Brent Appelman, Moritz Eggelbusch, Jelle Y. Huijts, Wendy Noort, Paul W. Hendrickse, Frank W. Bloemers, Jelle J. Posthuma, Paul van Amstel, Richie P. Goulding, Hans Degens, Richard T. Jaspers, Michèle van Vugt, Rob C.I. Wüst. Skeletal muscle properties in long COVID and ME/CFS differ from those induced by bed rest. medRxiv 2025.05.02.25326885; doi: https://doi.org/10.1101/2025.05.02.25326885 https://www.medrxiv.org/content/10.1101/2025.05.02.25326885v1.full?_x_tr_sl=nl&_x_tr_tl=en&_x_tr_hl=en (Full text)

Extracellular vesicle proteomics uncovers energy metabolism, complement system, and endoplasmic reticulum stress response dysregulation postexercise in males with myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating illness characterized by post-exertional malaise (PEM), a worsening of symptoms following exertion. The biological mechanisms underlying PEM remain unclear. Extracellular vesicles (EVs) play a key role in cell-cell communication and may provide insight into ME/CFS pathophysiology post-exertion. Emerging evidence suggests similarities between ME/CFS and Long COVID, including PEM and overlapping immune and metabolic dysfunctions, highlighting the need for deeper mechanistic understanding.

Methods: This study explores the EV proteome response to exercise in 10 males with ME/CFS and 12 well-matched sedentary male controls. Participants underwent a maximal cardiopulmonary exercise test, and plasma samples were collected at baseline, 15 min, and 24 h postexercise. EVs were isolated from plasma using size-exclusion chromatography and characterized with nanoparticle tracking analysis. EV protein abundance was quantified with untargeted proteomics (nanoLC-MS/MS). Comprehensive analyses included differential abundance, pathway enrichment, protein-protein interaction networks, and correlations between EV protein dynamics and clinical or exercise physiology data.

Results: ME/CFS patients exhibited many significantly altered EV proteomic responses compared with controls, including downregulation of TCA cycle-related proteins and upregulation of complement system proteins at 15 min postexercise. Changes in proteins involved in protein folding and the endoplasmic reticulum (ER) stress response during recovery were highly correlated with PEM severity, highlighting their potential as therapeutic targets. EV protein changes postexercise were also associated with disease severity and unrefreshing sleep. Correlations between EV protein levels and the exercise parameters VO₂ peak and ventilatory anaerobic threshold were observed in controls but were absent in ME/CFS patients, suggesting disrupted EV-mediated physiological processes.

Conclusions: ME/CFS patients exhibit a maladaptive EV proteomic response to exercise, characterized by metabolic impairments, immune overactivation, and ER stress response dysregulation. These findings provide insight into the molecular basis of PEM and suggest promising targets for improving recovery and energy metabolism in ME/CFS.

Source: Glass KA, Giloteaux L, Zhang S, Hanson MR. Extracellular vesicle proteomics uncovers energy metabolism, complement system, and endoplasmic reticulum stress response dysregulation postexercise in males with myalgic encephalomyelitis/chronic fatigue syndrome. Clin Transl Med. 2025 May;15(5):e70346. doi: 10.1002/ctm2.70346. PMID: 40465195; PMCID: PMC12135887. https://pmc.ncbi.nlm.nih.gov/articles/PMC12135887/ (Full text)

Low Dose Rapamycin Alleviates Clinical Symptoms of Fatigue and PEM in ME/CFS Patients via Improvement of Autophagy

Abstract:

Background: mTOR activation is associated with chronic inflammation in ME/CFS. Previous studies have shown that sustained mTOR activation can cause chronic muscle fatigue by inhibiting ATG13-mediated autophagy. This highlights the pivotal role of mTOR in the pathogenesis of ME/CFS.

Methods: We conducted a decentralized, uncontrolled trial of rapamycin in 86 patients with ME/CFS to evaluate its safety and efficacy. Low-dose rapamycin (6 mg/week) was administered, and core ME/CFS symptoms were assessed on days 30 (T1), 60 (T2), and 90 (T3). Plasma levels of autophagy metabolites, such as pSer258-ATG13 and BECLIN-1, were measured and correlated with clinical outcomes, specifically MFI.

Results: Rapamycin (6 mg/week) was tolerated without any SAEs. Of the 40 patients, 29 (72.5%) showed strong recovery in PEM, fatigue, and OI, along with improvements in MFI fatigue domains and SF-36 aspects. High levels of BECLIN-1 were detected in T3. Plasma pSer258-ATG13 levels were strongly downregulated at T1. Spearman’s correlation analysis indicated an association between autophagy impairment and reduced activity.

Conclusions: Low-dose rapamycin effectively reduced PEM and other key symptoms in patients with ME/CFS, as measured by BAS, SSS, MFI, and SF-36.  Future studies should encompass dose optimization and develop a diagnostic tool to identify responders with mTOR-mediated autophagy disruption.

Source: Brian T. Ruan, Sarojini Bulbule, Amy Reyes et al. Low Dose Rapamycin Alleviates Clinical Symptoms of Fatigue and PEM in ME/CFS Patients via Improvement of Autophagy, 03 June 2025, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-6596158/v1] https://www.researchsquare.com/article/rs-6596158/v1 (Full text)

Ignorance about post-exertional malaise and continued conflation of ME/CFS with chronic fatigue harms patients and stymies research progress

Dear Editor,

There are numerous issues with the opinion piece by Miller and coauthors. Most concern longstanding fallacies about the nature of ME/CFS and what patients believe about their illness, which — again — need to be corrected. I’d like to focus on just one: The defining and cardinal feature of ME/CFS is not fatigue, but rather post-exertional malaise (PEM).

PEM, sometimes referred to as post-exertional symptom exacerbation (PESE), can be defined as episodes during which people with ME/CFS experience significant worsening of existing symptoms and/or onset of new symptoms following amounts of physical or mental exertion or sensory stimuli that they could easily tolerate before the illness [1]. The length and severity of an episode of PEM are out of proportion to the amount of exertion or stimulus that triggered it; in severe or very severe ME/CFS patients, PEM may be triggered by, for example, short conversations with their carers or brief exposure to bright light, and these episodes may last week, months, or longer.

PEM remains poorly understood, but the concept and terminology have over recent years become much more mainstream, owing to the high prevalence of PEM in long covid [2]. The consensus opinion among ME/CFS patients is that daily activities and sensory input should be managed in such a way as to minimise PEM, because PEM severely impacts quality of life and can in some cases lead to further long-term deterioration in patients’ health and functional capacity. This concept forms the basis of pacing, an energy management strategy recommended by NICE [3].

In their opinion piece, Miller and coauthors ignore PEM when listing common symptoms of ME/CFS. This is an attempt to continue framing this illness as belonging to a family of ‘fatiguing conditions’, which, along with other ‘medically unexplained symptoms’, they argue can be treated with psychological interventions and rehabilitation.

Read the rest of this letter here: https://www.bmj.com/content/389/bmj.r977/rr-6

Repeated Cardiopulmonary Exercise Testing of ME/CFS Patients

Abstract:

Post-exertional malaise is a cardinal symptom present in 95% of individuals with myalgic encephalomyelitis (ME/CFS). Repeated cardiopulmonary exercise testing has been momentous in revealing that the physiological systems of those with ME/CFS are impaired or damaged and do not respond to exercise/physical activity like those without the condition. The 24-h repeated exercise test may demonstrate a reduction in peak oxygen consumption (VO2 peak), VO2 at ventilatory threshold, power output at both peak and ventilatory threshold, along with a reduction/diminished maximal heart rate commensurate with chronotropic intolerance. In this chapter, I describe the process and methods of repeated cardiopulmonary exercise testing, used to assess exercise tolerance in individuals with ME/CFS.

Source: Hodges L. Repeated Cardiopulmonary Exercise Testing of ME/CFS Patients. Methods Mol Biol. 2025;2920:163-172. doi: 10.1007/978-1-0716-4498-0_10. PMID: 40372683. https://link.springer.com/protocol/10.1007/978-1-0716-4498-0_10

Post-exertional malaise in Long COVID: subjective reporting versus objective assessment

Abstract:

Background: Post-exertional malaise (PEM) is a central feature of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and has emerged as a prominent feature of Long COVID. The optimal clinical approach to PEM is inconclusive, and studies of the impact of exercise have yielded contradictory results.

Objective: The objective of this study was to examine PEM in Long COVID by assessing the prevalence of self-reported PEM across study cohorts and symptom responses of Long COVID patients to a standardized exercise stressor. Secondarily, Long COVID symptom responses to exercise were compared to those of ME/CFS and healthy volunteers.

Methods: Data from three registered clinical trials comprised four cohorts in this study: Long COVID Questionnaire Cohort (QC; n = 244), Long COVID Exercise Cohort (EC; n = 34), ME/CFS cohort (n = 9), and healthy volunteers (HV; n = 9). All cohorts completed questionnaires related to physical function, fatigue, and/or PEM symptoms. EC also performed a standardized exercise test (cardiopulmonary exercise test, CPET), and the PEM response to CPET was assessed using visual analog scales and qualitative interviews (QIs) administered serially over 72 h. EC PEM measures were compared to ME/CFS and HV cohorts. A secondary analysis of QI explored positive responses to CPET among EC, ME/CFS and HV.

Results: Self-reported PEM was 67% in QC and estimated at 27% in EC. Only 2 of 34 EC patients (5.9%) were observed to develop PEM after a CPET. In addition, PEM responses after CPET in Long COVID were not as severe and prolonged as those assessed in ME/CFS. Twenty-two of 34 EC patients (64.7%) expressed at least one of 7 positive themes after the CPET.

Conclusion: Self-report of PEM is common in Long COVID. However, observable PEM following an exercise stressor was not frequent in this small cohort. When present, PEM descriptions during QI were less severe in Long COVID than in ME/CFS. Positive responses after an exercise stressor were common in Long COVID. Exercise testing to determine the presence of PEM may have utility for guiding clinical management of Long COVID.

Source: Stussman B, Camarillo N, McCrossin G, Stockman M, Norato G, Vetter CS, Ferrufino A, Adedamola A, Grayson N, Nath A, Chan L, Walitt B, Chin LMK. Post-exertional malaise in Long COVID: subjective reporting versus objective assessment. Front Neurol. 2025 Apr 23;16:1534352. doi: 10.3389/fneur.2025.1534352. PMID: 40337174; PMCID: PMC12055772. https://pmc.ncbi.nlm.nih.gov/articles/PMC12055772/ (Full text)

Assessing the Relationship in Symptomology of Myalgic Encephalitis/Chronic Fatigue Syndrome and Long COVID

Abstract:

The symptomology of Myalgic Encephalitis/Chronic Fatigue Syndrome (ME/CFS) shares many commonalities with Long COVID (LC). This study aimed to clearly define the comparison between ME/CFS and LC in terms of symptomology.

A cross-sectional analysis of 27,651 interviewees from a National Health Interview Survey 2022 adult dataset was conducted. The data was controlled for subject’s sex, race/ethnicity, age, life satisfaction, insurance coverage, poverty ratio, and comorbidities. A logistic regression was used to compare four groups: (1) LC individuals, (2) ME/CFS individuals, (3) LC with ME/CFS individuals, and (4) controls by symptoms of depression, anxiety, physical activity, fatigue, and memory.

The results showed that subjects with both ME/CFS and LC were more likely to report memory issues, anxiety, depression, fatigue, and difficulty with physical activity followed by subjects with ME/CFS only, LC only, and the controls (P < .01).

Our study suggests a synergistic mechanism between ME/CFS and LC in developing issues with anxiety, depression, fatigue, and physically activity in patients. The study’s conclusions highlight the need to elucidate the possible overlap in pathophysiological mechanisms of ME/CFS and LC in the symptomology of patients.

Source: Garapaty N, Reyes KM, Tehrani L, Mendoza MB, Hardigan P. Assessing the Relationship in Symptomology of Myalgic Encephalitis/Chronic Fatigue Syndrome and Long COVID. Am J Med Open. 2025 Feb 1;13:100085. doi: 10.1016/j.ajmo.2024.100085. PMID: 40271015; PMCID: PMC12017839. https://pmc.ncbi.nlm.nih.gov/articles/PMC12017839/ (Full text)

Awareness and Perception of Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Among Pain Specialists: A Questionnaire-Based Study

Abstract:

Background: This study aims to explore the perceptions and clinical approaches of pain management specialists toward myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a condition characterized by persistent fatigue, widespread pain, unrefreshing sleep, and autonomic dysfunction. Given the challenges in diagnosis and management, pain specialists may play a pivotal role in symptom relief. By identifying variations in evaluation and treatment practices, this study seeks to enhance the recognition of ME/CFS and improve its clinical management within pain medicine.

Material and methods: The questionnaire was distributed in printed form to 250 pain specialists in Turkey. Given the limited number of pain physicians in the country, the study aimed to encompass all actively practicing specialists. The survey included four demographic questions, eight true-false questions, 12 multiple-choice questions, and four rating-scale questions. Data were collected anonymously. Data were analyzed using Statistical Product and Service Solutions (SPSS, version 27.0; IBM SPSS Statistics for Windows, Armonk, NY), with descriptive statistics and chi-square (χ²) tests applied to examine the relationships between awareness levels and attitudinal variables.

Results: In Turkey, 106 pain medicine physicians (42.4%) participated in the study. The average age was 40.6±8.52 years. Among the participants, 39.6% had previously heard of myalgic encephalomyelitis. Physicians were inclined to first ask the question, “Do you think you get enough sleep at night?” when evaluating these patients, with a rate of 63.2%. The majority of participants (65.9%) stated that they “occasionally” or “rarely” considered the relationship between fatigue and orthostatic intolerance. Additionally, 37.7% believed that this disease is a subtype of depression. The statement, “chronic fatigue decreases with intense aerobic exercise,” was agreed upon by 50.9% of participants. This controversial statement was particularly more common among those who were unaware of ME/CFS’s alternative name (p=0.009) and those who did not take dysautonomic disorders into account (p=0.048). When considering an ME/CFS diagnosis, physicians most frequently referred patients to the physical medicine and rehabilitation department (32.1%). Those who preferred not to refer patients to any department (12.3%) tended to find it appropriate for a patient to seek consultation at a pain medicine clinic due to widespread body pain and fatigue (χ2=11.405, p=0.044).

Conclusion: This study is the first questionnaire-based research assessing pain physicians’ awareness and attitudes toward ME/CFS. By highlighting their perspectives on its evaluation and management, our findings may improve recognition and clinical approaches to ME/CFS. Future research should focus on education and standardized guidelines to enhance patient care.

Source: Uygun GG, Gözükızıl ST, Bilen A. Awareness and Perception of Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Among Pain Specialists: A Questionnaire-Based Study. Cureus. 2025 Mar 23;17(3):e81030. doi: 10.7759/cureus.81030. PMID: 40264626; PMCID: PMC12013460. https://pmc.ncbi.nlm.nih.gov/articles/PMC12013460/ (Full text)

How I treat my patients with Myalgic Encephalomyelitis, Chronic Fatigue Syndrome (ME/CVS), fibromyalgia or “long COVID”

Abstract:

Common to Myalgic encephalomyelitis, chronic fatigue syndrome and so-called long Covid is the panoply of complaints, with Post Exertional Malaise (PEM) as the most typical symptom. Added to that are permanent feeling of fatigue, decreased capacity to concentrate, so-called brain fog, non restorative sleep, diffuse pain, and – in case of long Covid – respiratory distress.

Several recent studies have confirmed my original hypothesis that poor metabolism and energy production by the mitochondria are responsible for the majority of these phenomena. I have suggested that inhibition of Pyruvate dehydrogenase (Pdh) activity is the major reason for this. Pdh inhibition is probably caused by the excess of the phosphatase: Pyruvate Dehydrogenase Kinase (PDK). The latter results from “Systemic Immune Disorder” (what I called “SID”) and inflammation.

Based on this hypothesis I have applied oral and infusion treatment modalities which were successful in approximately 80% of 130 consecutive patients. The pivotal substances are sodium dichloroacetate, that reduces PDK, Meldonium, that facilitates intracellular glucose metabolism, and low dose Nalexone, that optimises the function of microglia.

Source: Comhaire F. How I treat my patients with Myalgic Encephalomyelitis, Chronic Fatigue Syndrome (ME/CVS),
Fibromyalgia or “long COVID”. J Clin Images Med Case Rep. 2025; 6(3): 3508. https://jcimcr.org/pdfs/JCIMCR-v6-3508.pdf (Full text)