Tag: symptom severity

Identifying post-exertional malaise subtypes: Differentiating physical and mental PEM manifestations

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic illness with post-exertional malaise (PEM) as a key symptom. This study categorized participants with ME/CFS who met PEM criteria into four groups based on severity of physical and mental PEM: severe physical PEM (Physical group), severe mental PEM (Mental group), both severe (Both group), or neither severe (Neither group). A control group was also included.

The Both group exhibited the highest symptom severity, while the Neither group displayed lower scores. The Neither group experienced less disability than other ME/CFS subtypes but was significantly more disabled than Controls. Health assessments revealed that Controls had the highest functioning, followed by the Neither group, with the Both group showing greatest impairment. These results indicate distinct PEM subtypes, emphasizing the need to recognize different manifestations of this complex symptom. Future research should include diverse control groups, longitudinal data, and biological measures to further understand PEM subtypes.

Source: Tuzzolino K, Jason LA, Furst J. Identifying post-exertional malaise subtypes: Differentiating physical and mental PEM manifestations. J Health Psychol. 2026 Feb 28:13591053261420598. doi: 10.1177/13591053261420598. Epub ahead of print. PMID: 41761780. https://pubmed.ncbi.nlm.nih.gov/41761780/

Temporal dynamics of the plasma proteomic landscape reveals maladaptation in ME/CFS following exertion

Abstract:

The overarching symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is post-exertional malaise (PEM), an exacerbation of symptoms following physical or mental exertion. To investigate the molecular underpinnings of PEM, we performed longitudinal plasma proteomics using the Somascan® 7K aptamer-based assay to monitor 6,361 unique plasma proteins in 132 individuals (96 females and 36 males) subjected to two maximal cardiopulmonary exercise tests separated by a 24-hour recovery period.

The cohort included 79 ME/CFS cases compared to 53 age- and BMI-matched sedentary controls, allowing us to distinguish disease-specific molecular alterations from those due to physical deconditioning. Longitudinal profiling revealed widespread proteomic changes following exertion, with the most pronounced alterations observed in ME/CFS participants during the recovery phase, coinciding with the onset of PEM.

Compared to controls, ME/CFS subjects showed persistent dysregulation of immune, metabolic, and neuromuscular pathways. Key findings included suppression of T and B cell signaling, downregulation of IL-17 and cell-cell communication pathways, and upregulation of glycolysis/gluconeogenesis, suggestive of mitochondrial stress and impaired immune recovery from exercise. Proteomic associations with physiological performance (VO2max, anaerobic threshold) revealed disruptions between protein abundance and exercise capacity in ME/CFS versus controls.

Correlations with symptom severity linked changes in immune-related proteins and ME/CFS symptoms including muscle pain, recurrent sore throat, and lymph node tenderness. Sex-stratified analyses revealed distinct molecular responses between females and males, emphasizing the importance of considering sex as a biological variable in ME/CFS research.

Finally, our analysis of sedentary controls contributes new data of molecular responses to acute exertion in a predominantly female sedentary cohort, a population historically underrepresented in exercise physiology studies. Together, these findings underscore the value of dynamic, proteomic profiling over time for characterizing maladaptive responses to exertion in ME/CFS and provide a foundation for deeper mechanistic investigation into PEM.

Source: Germain A, Glass KA, Eckert MA, Giloteaux L, Hanson MR. Temporal dynamics of the plasma proteomic landscape reveals maladaptation in ME/CFS following exertion. Mol Cell Proteomics. 2025 Nov 12:101467. doi: 10.1016/j.mcpro.2025.101467. Epub ahead of print. PMID: 41237904. https://www.mcponline.org/article/S1535-9476(25)00566-3/fulltext (Full text)

Circulating Levels of SMPDL3B Define Metabolic Endophenotypes and Subclinical Kidney Alterations in Myalgic Encephalomyelitis

Abstract:

Myalgic Encephalomyelitis (ME) is a complex, multisystem disorder with poorly understood pathophysiological mechanisms. SMPDL3B, a membrane-associated protein expressed in renal podocytes, is essential for lipid raft integrity and glomerular barrier function. We hypothesize that reduced membrane-bound SMPDL3B may contribute to podocyte dysfunction and impaired renal physiology in ME. To investigate this, we quantified soluble SMPDL3B in plasma and urine as a surrogate marker of membrane-bound SMPDL3B status and assessed renal clearance and plasma metabolomic profiles.
In a cross-sectional study of 56 ME patients and 16 matched healthy controls, ME patients exhibited significantly lower urine-to-plasma ratios of soluble SMPDL3B and reduced renal clearance, suggesting podocyte-related abnormalities. Plasma metabolomics revealed dysregulation of metabolites associated with renal impairment, including succinic acid, benzoic acid, phenyllactic acid, 1,5-anhydroglucitol, histidine, and citrate.
In ME patients, plasma SMPDL3B levels inversely correlated with 1,5-anhydroglucitol concentrations and renal clearance. Multivariable modeling identified the urine-to-plasma SMPDL3B ratio as an independent predictor of clearance. Female ME patients showed more pronounced SMPDL3B alterations, reduced clearance, and greater symptom severity. Non-linear associations between soluble SMPDL3B and lipid species further suggest systemic metabolic remodeling.
These findings support soluble SMPDL3B as a potential non-invasive biomarker of renal-podocyte involvement in ME, highlighting sex-specific differences that may inform future therapeutic strategies.
Source: Rostami-Afshari B, Elremaly W, McGregor NR, Huang KJK, Armstrong CW, Franco A, Godbout C, Elbakry M, Abdelli R, Moreau A. Circulating Levels of SMPDL3B Define Metabolic Endophenotypes and Subclinical Kidney Alterations in Myalgic Encephalomyelitis. International Journal of Molecular Sciences. 2025; 26(18):8882. https://doi.org/10.3390/ijms26188882 https://www.mdpi.com/1422-0067/26/18/8882 (Full text)

Autoantibody targeting therapies in post COVID syndrome and myalgic encephalomyelitis/chronic fatigue syndrome

Introduction:

Following the shift of SARS-CoV-2 from pandemic to endemic, post COVID syndrome (PCS) joins the list of already known post-acute infection syndromes (PAIS) and its most severe manifestation, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The exact pathomechanism of PCS has not yet been fully understood. Immune dysregulation with persistent inflammation, microvascular injury with endothelial dysfunction, autonomic nervous system dysfunction, mitochondrial dysfunction, gut microbiome dysbiosis and persistence of SARS-CoV-2 virus or SARS-CoV-2 viral particles have been proposed [1].

Autoimmunity could be a linking element across various mechanisms and there is indeed mounting evidence that autoantibodies (AAbs) in particular play a role in a subset of PCS and ME/CFS. In ME/CFS there are now numerous studies showing elevated levels and altered functions of G-protein coupled receptor autoantibodies (GPCR AAbs) and their correlation with severity of key symptoms [2]. First trials with AAb-targeting therapies show promising though mixed results. These include studies directly targeting AAbs by removal with immunoadsorption or their enhanced degradation with efgartigimod or neutralization with BC007 (rovunaptabin). Further B cell depletion with rituximab or plasma cell depletion with daratumumab has yielded some positive but inconsistent results.

Source: Wohlrab F, Eltity M, Ufer F, Paul F, Scheibenbogen C, Bellmann-Strobl J. Autoantibody targeting therapies in post COVID syndrome and myalgic encephalomyelitis/chronic fatigue syndrome. Expert Opin Biol Ther. 2025 Apr 10. doi: 10.1080/14712598.2025.2492774. Epub ahead of print. PMID: 40211686. https://www.tandfonline.com/doi/full/10.1080/14712598.2025.2492774#d1e211 (Full text)

Impaired Hand Grip Strength Correlates with Greater Disability and Symptom Severity in Post-COVID Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Post-COVID syndrome (PCS) encompasses a diverse array of symptoms persisting beyond 3 months after acute SARS-CoV-2 infection, with mental as well as physical fatigue being the most frequent manifestations.
Methods: In 144 female patients with PCS, hand grip strength (HGS) parameters were assessed as an objective measure of muscle fatigue, with 78 meeting the Canadian Consensus Criteria for postinfectious myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The severity of disability and key symptoms was evaluated using self-reported questionnaires.
Results: Patients with ME/CFS exhibited heightened overall symptom severity, including lower physical function (p < 0.001), a greater degree of disability (p < 0.001), more severe fatigue (p < 0.001), postexertional malaise (p < 0.001), and autonomic dysfunction (p = 0.004) compared to other patients with PCS. While HGS was impaired similarly in all patients with PCS and exhibited a significant correlation with physical function across the entire patient group, HGS of patients with ME/CFS uniquely demonstrated associations with key symptoms.
Conclusions: Thus, impaired HGS serves as an objective marker of physical function in patients with PCS. Only in patients meeting ME/CFS criteria is impaired HGS also associated with the severity of hallmark symptoms. This suggests a common mechanism for muscle fatigue and other symptoms in the ME/CFS subtype, distinct from that in other types of PCS.
Source: Paffrath A, Kim L, Kedor C, Stein E, Rust R, Freitag H, Hoppmann U, Hanitsch LG, Bellmann-Strobl J, Wittke K, et al. Impaired Hand Grip Strength Correlates with Greater Disability and Symptom Severity in Post-COVID Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Journal of Clinical Medicine. 2024; 13(7):2153. https://doi.org/10.3390/jcm13072153 https://www.mdpi.com/2077-0383/13/7/2153

Worsening Symptoms Is Associated with Larger Cerebral Blood Flow Abnormalities during Tilt-Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Abstract:

Background and Objectives: During tilt testing, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients experience an abnormal reduction in cerebral blood flow (CBF). The relationship between this CBF reduction and symptom severity has not been examined in detail. Our hypothesis was that ME/CFS severity is related to the degree of the CBF reduction during tilt testing.
Materials and Methods: First, from our database, we selected ME/CFS patients who had undergone assessments of ME/CFS symptomatology and tilt tests on the same day, one at the first visit and the second during a follow-up. The change in symptomatology was related to the change in CBF during the tilt test. Second, we combined the data of two previously published studies (n = 219), where disease severity as defined by the 2011 international consensus criteria (ICC) was available but not published.
Results: 71 patients were retested because of worsening symptoms. The ICC disease severity distribution (mild-moderate-severe) changed from 51/45/4% at visit-1 to 1/72/27% at follow-up (p < 0.0001). The %CBF reduction changed from initially 19% to 31% at follow-up (p < 0.0001). Of 39 patients with stable disease, the severity distribution was similar at visit-1 (36/51/13%) and at follow-up (33/49/18%), p = ns. The %CBF reduction remained unchanged: both 24%, p = ns. The combined data of the two previously published studies showed that patients with mild, moderate, and severe disease had %CBF reductions of 25, 29, and 33%, respectively (p < 0.0001).
Conclusions: Disease severity and %CBF reduction during tilt testing are highly associated in ME/CFS: a more severe disease is related to a larger %CBF reduction. The data suggest a causal relationship where a larger CBF reduction leads to worsening symptoms.
Source: van Campen CMC, Rowe PC, Visser FC. Worsening Symptoms Is Associated with Larger Cerebral Blood Flow Abnormalities during Tilt-Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Medicina. 2023; 59(12):2153. https://doi.org/10.3390/medicina59122153 https://www.mdpi.com/1648-9144/59/12/2153 (Full text)
Source:

Initial COVID-19 Severity and Long-COVID Manifestations: An Observational Analysis

Abstract:

Objective: New-onset or persistent symptoms beyond after 4 weeks from COVID-19 are termed “long-COVID.” Whether the initial severity of COVID-19 has a bearing on the clinicoradiological manifestations of long COVID is an area of interest.

Material and methods: We did an observational analysis of the long-COVID patients after categorizing them based on their course of COVID-19 illness into mild, moderate, and severe groups. The clinical and radiological profile was compared across these groups.

Results: Out of 150 long-COVID patients recruited in the study, about 79% (118), 14% (22), and 7% (10) had a history of mild, moderate, and severe COVID-19, respectively. Fatigue (P = .001), breathlessness (P = .001), tachycardia (P = .002), tachypnea (P < .001), raised blood pressure (P < .001), crepitations (P = .04), hypoxia at rest (P < .001), significant desaturation in 6-minute walk test (P = .27), type 1 respiratory failure (P = .001), and type 2 respiratory failure (P = .001) were found to be significantly higher in the long-COVID patients with a history of severe COVID-19. These patients also had the highest prevalence of abnormal chest X-ray (60%) and honeycombing in computed tomography scan thorax (25%, P = .027).

Conclusion: The course of long COVID bears a relationship with initial COVID-19 severity. Patients with severe COVID-19 are prone to develop more serious long-COVID manifestations.

Source: Goel N, Goyal N, Spalgais S, Mrigpuri P, Varma-Basil M, Khanna M, Nagaraja R, Menon B, Kumar R. Initial COVID-19 Severity and Long-COVID Manifestations: An Observational Analysis. Thorac Res Pract. 2023 Jan;24(1):22-28. doi: 10.5152/ThoracResPract.2023.21307. PMID: 37503595. https://thoracrespract.org/en/initial-covid-19-severity-and-long-covid-manifestations-an-observational-analysis-165530 (Full text as PDF file)

Comparing Frequency and Severity Ratings for ME/CFS versus Controls

Abstract:

Most questionnaires for somatic symptoms focus on occurrence, frequency, or severity, and in doing so, they might not be able to comprehensively assess the burden that symptoms present to patients. For example, a symptom might occur at a high frequency but only a minimal severity, so that it is less likely to be a burden on a patient; whereas a symptom that has both a high frequency and severity is more likely to be negatively impacting a patient.
Study 1 examined frequency and severity scores for classic Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) symptoms among patients with ME/CFS versus a control group. Findings in Study 1 indicate there were more frequency/severity discrepancies for individuals with ME/CFS versus the control group. Study 1 concluded that collecting data on both measures of symptom burden provides unique indicators that can better assess the burden of the symptoms on patients.
In a separate data set, Study 2 reported reliability data on slight differences in the time period and the way the severity was assessed. Study 2 findings indicated high levels of reliability for these changes in the time period and the way questions were asked. These studies provide important psychometric properties that could lead to more reliable and valid assessments of patients with post-viral illnesses.
Source: Jason LA, Benner S, Hansel N. Comparing Frequency and Severity Ratings for ME/CFS versus Controls. Psych. 2023; 5(3):662-669. https://doi.org/10.3390/psych5030042 https://www.mdpi.com/2624-8611/5/3/42 (Full text)

Modulation of Beta-Adrenergic Autoantibodies Over Time in Post-Viral ME/CFS is Related to Fatigue and Pain Symptoms

Abstract:

Background: Myalgic encephalomyelits/chronic fatigue syndrome (ME/CFS) is an acquired disease with symptoms of fatigue and pain. In pathogenesis, the induction of autoantibodies (AAB) against G-protein coupled receptors (GPCR), such as β-adrenergic receptors (β-AdR), has been suspected. GPCR-AAB correlate with symptom severity and autonomic dysfunction in ME/CFS.

Objectives: To describe symptoms and treatment of a patient presenting with infection-triggered ME/CFS demonstrating that levels of β-AdR-AAB underlie modulation over time, correlating with the severity of symptoms.

Methods: At T1 and T2, GPCR-AAB were measured and questionnaires assessing symptom severity were completed. TSHDS-IgM-AAB were tested, and SF density was analyzed via skin probe.

Results: At T2, elevated levels of β-AdR-AAB were found, corresponding with an aggravation of fatigue and pain symptoms. Elevated TSHDS-IgM-AAB were found, which corresponded with reduced fiber density from the skin probe.

Conclusions: The levels of β-AdR-AAB in post-infectious ME/CFS can be modulated. Future studies might target interventions to reduce these AAB.

Source: Busch L, Schriek C, Paul M, Heidecke H. Modulation of Beta-Adrenergic Autoantibodies Over Time in Post-Viral ME/CFS is Related to Fatigue and Pain Symptoms. Isr Med Assoc J. 2023 Apr;25(4):259-264. PMID: 37129123. https://pubmed.ncbi.nlm.nih.gov/37129123/

The Role of Leptin and Inflammatory Related Biomarkers in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Purpose: Leptin is a member of the cytokine family; its receptor (LEPR-b) is the longest form receptor expressed in cells of the immune system; wherein LEPR-b deficiency causes a decrease in CD4+ cells. LEPR-b is located in hypothalamic and brain stem nuclei, and it primarily regulates energy status. As well, leptin indirectly regulates widespread pain and exercise tolerance by decreasing circulating cortisol.

Hyperinsulinemia increases leptin production in adipocytes on a diurnal rhythm; however, the precise relationship between insulin, leptin and pro-inflammatory markers remains uncertain. In clinical settings, high-sensitivity C-reactive protein (hsCRP) has been widely used, as an inflammatory predictor for leptin-related cardiometabolic outcomes and chronic inflammatory symptoms.

Leptin-related metabolic and inflammation dysregulations have been clinically reported in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), but not fully elucidated. We examined the association of plasma insulin, leptin, and hsCRP levels with ME/CFS self-reported symptom severity.

Methods: Prospective analyses were conducted on ME/CFS patients who met Fukuda/CDC criteria at Birmingham hospital, Alabama, U.S.A. The independent variables were hyperinsulinemia (>174 μIU/mL), hyperleptinemia/hypoleptinemia (>18.3/<3.3 ng/mL), residual inflammation risk (hsCRP ≥2 and ≠26.2 mg/L) and within-individual-variability (WIV) for each biomarker.

WIV was defined for each individual as standard deviation/sample residuals adjusting for time and calculated from once-daily random plasma samples over 10–12 weeks.

The primary outcomes were:

(1) ME/CFS symptom score trends [generalized pain, persistent fatigue, sleep disturbance, impairment of concentration and memory (brain fog), and post-exertional malaise (PEM)] calculated from the MFI-20 questionnaire with anchors from 0 to 100 and recorded once daily over a matching 12–14 weeks, and

(2) dichotomized symptom severity, with severe symptoms defined as scores > 60/100. After adjusting for age and time, we reported: (1) standard errors (SEM) and p-values for symptom trends using multivariable mixed-effect linear regression models, and (2) odds ratios for severe symptoms using multivariable alternating logistic regression models.

Results: We included 29 ME/CFS patients. All were females and >18 years old. Hyperinsulinemia, hyperleptinemia/hypoleptinemia, and residual inflammation risk were 7%, 80%/7%, and 74%, respectively.

The medians of insulin-WIV, leptin-WIV and hsCRP-WIV were [(0.24; IQR 0.15–0.38), (0.25; IQR 0.15–0.40), (0.33; IQR 0.18–0.51)] respectively. On average, hyperleptinemic patients had the highest leptin-WIV and 50% of them had residual inflammation risk.

Severe (fatigue, pain, brain fog, sleep disturbance, and PEM) were reported in 50%, 29%, 41%, 30%, and 57% of patients, respectively. In the adjusted analysis, worse fatigue scores (7.49; SEM, 2.23; p = 0.002) were associated with higher insulin-WIV.

Hyperleptinemia (OR 1.54; 95% CI 1.13–2.09) compared to hypoleptinemia, and residual inflammation risk (OR 1.65; 95% CI 1.21–2.25) were associated with higher odds of severe fatigue. Worse pain scores (7.17; SEM, 2.30; p = 0.005) were associated with higher leptin-WIV, and (8.45; SEM, 2.25; p = 0.0009) higher hsCRP-WIV, and residual inflammation risk (OR 1.75; 95% CI 1.34–2.29) was associated with higher odds of severe pain.

Severe brain fog scores (9.20; SEM, 2.44; p = 0.0008) were associated with higher insulin-WIV, higher leptin-WIV (4.73; SEM, 2.12; p = 0.03). Residual inflammation risk (OR 1.40; 95% CI 1.16–1.77) was associated with higher odds of severe brain fog.

Hyperleptinemia (OR 0.60; 95% CI 0.43–1.19) was associated with lower odds of severe PEM compared to hypoleptinemia, and better sleep quality was associated (6.07; SEM, 1.70; p = 0.001) with higher insulin-WIV, and (3.37; SEM, 1.47; p = 0.03) higher leptin-WIV.

Conclusions: In patients with ME/CFS, symptoms severity was associated with hyperleptinemia, inflammation and within-individual-variability of these biomarkers. Leptin and hsCRP may be clinically useful in predicting symptom severity.

Larger clinical trials are needed to further examine the prediction and causality of these biomarkers in the development of ME/CFS diagnosis. The efficacy and safety of anti-inflammatory therapies may be evaluated in sub-clusters of ME/CFS with metabolic responses and inflammation dysregulations to improve patient-reported symptoms.

Source: Rahaf Al Assil and Jarred W Younger. “The Role of Leptin and Inflammatory Related Biomarkers in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome” in Karandrea S, Agarwal N, Organizing Committee of Cardiometabolic Health Congress. Report from the Scientific Poster Session at the 16th Annual Cardiometabolic Health Congress in National Harbor, USA, 14–17 October 2021. Proceedings. 2022; 80(1):6. https://doi.org/10.3390/proceedings2022080006 (Full text)