Category: Immune System

Deep sequencing of BCR heavy chain repertoires in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a common and debilitating chronic illness of unknown aetiology. Chronic infection and autoimmune responses have been proposed as two mechanisms that potentially underlie the pathogenesis of ME/CFS. To explore these disease hypotheses, we characterised the antigen-specific receptors of B cells using adaptive immune receptor repertoire sequencing.

We compared the B-cell receptor (BCR) repertoires of 25 patients with mild/moderate ME/CFS, 36 patients with severe ME/CFS, 21 healthy controls, and 28 patients with multiple sclerosis (MS) to identify signatures of infection or autoimmune responses. ME/CFS patients did not display increased clonality or differential somatic hypermutation compared to healthy controls and patients with MS.

One of two immunoglobulin heavy variable (IGHV) genes, IGHV3-30, reported to be increased in ME/CFS patients in a previous study, was replicated in patients with mild/moderate disease in our cohort. However, there was no evidence of ongoing adaptive responses in IGHV3-30 repertoires from mild/moderate ME/CFS patients with increased IGHV3-30 usage.

There were no detectable repertoire signatures associated with infection or autoimmunity in repertoires from ME/CFS patients, but we observed skewing of the ratio of IgM to IgG BCRs in patients with mild/moderate ME/CFS, a preliminary finding that presents an opportunity for follow-up work.

Source: Ryback AA, Cowan GJM. Deep sequencing of BCR heavy chain repertoires in myalgic encephalomyelitis/chronic fatigue syndrome. Front Immunol. 2025 Feb 17;16:1489312. doi: 10.3389/fimmu.2025.1489312. PMID: 40034707; PMCID: PMC11872726. https://pmc.ncbi.nlm.nih.gov/articles/PMC11872726/ (Full text)

Mapping the Complexity of ME/CFS: Evidence for Abnormal Energy Metabolism, Altered Immune Profile and Vascular Dysfunction

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disorder with no known underlying mechanisms, diagnostic tools, or treatments.  Multiple areas of dysfunction have been extensively studied, but rarely examined together. We recruited age- and sex-matched ME/CFS patients and healthy controls for a multi-modal study examining energy metabolism, immune profiles and plasma protein levels.

Elevated levels of adenosine monophosphate (AMP) were detected in both plasma and immune cells. Additionally, immune cells showed higher levels of adenosine diphosphate (ADP) and a reduced adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio.

These findings imply decreased ATP generation and the presence of energy stress within the immune cell population. Adaptive immune cell populations were skewed towards less mature effector subsets of CD4+, CD8+ and gd T cells, and proportions of CD1c+CD141-conventional DC type 2 (cDC2) and CD56lowCD16+ terminal natural killer (NK) cells were also reduced. Elevated levels of plasma proteins associated with thrombus formation and vascular reactivity may contribute to the endothelial dysfunction observed in ME/CFS patients. Using Classification and Regression Tree (CART) modelling, we identified variables from each mode of investigation with strong predictive potential for ME/CFS. Together, this study provides new insights into the somatic symptoms and underlying biology of ME/CFS.

Source: Heng, Ruiwen Benjamin and Gunasegaran, Bavani and Krishnamurthy, Shivani and Bustamante, Sonia and Staats, Ananda and Chow, Sharron and Ahn, Seong Beom and Paul-Heng, Moumita and Maciver, Yolande and Smith, Kirsten and Tran, Denise Phuong and Howley, Peter P. and Bilgin, Ayse Aysin and Sharland, Alexandra and Schloeffel, Richard and Guillemin, Gilles J. and Administrator, Sneak Peek, Mapping the Complexity of ME/CFS: Evidence for Abnormal Energy Metabolism, Altered Immune Profile and Vascular Dysfunction. Available at SSRN: https://ssrn.com/abstract=5131664 or http://dx.doi.org/10.2139/ssrn.5131664  https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5131664 (Full text available as PDF file)

Reactivated EBV, HHV6, HAdV in Sputum from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients: Are autoAbs to IFN-I Impairing Antiviral Immunity?

Abstract:

An exhausted antiviral immune response is observed in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID. In this study, potential mechanisms behind this exhaustion were investigated. First, the viral load of EBV, HAdV, human cytomegalovirus (HCMV), human herpesvirus 6 (HHV6), and SARS-CoV-2 was determined in sputum samples (n=29) derived from ME/CFS patients (n=13), healthy controls (n=10), elderly healthy controls (n=4), and immunosuppressed controls (n=2). Secondly, autoAbs to type I interferon (IFN-I) in sputum were analyzed to possibly explain impaired viral immunity.

We found that ME/CFS patients released EBV at a significantly higher level compared to controls (p=0.0256). HHV6 was present in ~50% of all participants at the same level. HAdV was detected in two cases with immunosuppression and severe ME/CFS, respectively. HCMV and SARS-CoV-2 were found only in immunosuppressed controls. Notably, anti-IFN-I autoAbs in ME/CFS and controls did not differ, except in severe ME/CFS with high levels.

We conclude that ME/CFS patients, compared to controls, have a significantly higher load of EBV. IFN-I autoAbs cannot explain IFN-I dysfunction, with the possible exception of severe cases showing elevated autoAbs, also reported in severe SARS-CoV-2. We forward that additional mechanisms, such as viral evasion of IFN-I effect, may be present in ME/CFS, which demands further studies.

Source: Hannestad, U., Allard, A., Nilsson, K., & Rosén, A. (2025). Reactivated EBV, HHV6, HAdV in Sputum from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients: Are autoAbs to IFN-I Impairing Antiviral Immunity?. Preprints. https://doi.org/10.20944/preprints202502.0185.v1 https://www.preprints.org/manuscript/202502.0185/v1 (Full text available as PDF file)

Abnormal T-Cell Activation And Cytotoxic T-Cell Frequency Discriminates Symptom Severity In Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating but poorly-understood disease. ME/CFS symptoms can range from mild to severe, and include immune system effects alongside incapacitating fatigue and post-exertional disease exacerbation. In this study, we examined immunological profiles of people living with ME/CFS by flow cytometry, focusing on cytotoxic cells, to determine whether people with mild/moderate (n= 43) or severe ME/CFS (n=53) expressed different immunological markers.

We found that people with mild/moderate ME/CFS had increased expression of cytotoxic effector molecules alongside enhanced proportions of early-immunosenescence cells, determined by the CD28 – CD57 – phenotype, indicative of persistent viral infection. In contrast, people with severe ME/CFS had higher proportions of activated circulating lymphocytes, determined by CD69 + and CD38 + expression, and expressed more pro-inflammatory cytokines, including IFNγ, TNF and IL-17, following stimulation in vitro , indicative of prolonged non-specific inflammation.

These changes were consistent across different cell types including CD8 + T cells, mucosal associated invariant T cells and Natural Killer cells, indicating generalised altered cytotoxic responses across the innate and adaptive immune system. These immunological differences likely reflect different disease pathogenesis mechanisms occurring in the two clinical groups, opening up opportunities for the development of prognostic markers and stratified treatments.

Source: Lee JS, Lacerda E, Kingdon C, Susannini G, Dockrell HM, Nacul L, Cliff JM. Abnormal T-Cell Activation And Cytotoxic T-Cell Frequency Discriminates Symptom Severity In Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. medRxiv [Preprint]. 2025 Jan 6:2025.01.02.24319359. doi: 10.1101/2025.01.02.24319359. PMID: 39830245; PMCID: PMC11741448. https://pubmed.ncbi.nlm.nih.gov/39830245/

Autoantibody-Driven Monocyte Dysfunction in Post-COVID Syndrome with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Post-COVID syndrome (PCS) has emerged as a significant health concern with persisting symptoms. A subset of PCS patients develops severe myalgic encephalomyelitis/chronic fatigue syndrome (pcME/CFS). Dysregulated autoantibodies (AABs) have been implicated in PCS, contributing to immune dysregulation, impairment of autonomous nerve and vascular function. As recently shown in autoimmune diseases, IgG fractions translate disease-specific pathways into various cells. Therefore, we asked whether IgG fractions from PCS patients could be applied in vitro to identify specific cytokine rersponses for PCS patients without (nPCS) and with pcME/CSF.

To assess this, we have stimulated monocyte cell lines with IgG fractions from PCS patients. Our findings reveal distinct patterns of immune regulation by AABs in vascular and immune dysfunction. In contrast to nPCS, pcME/CSF AABs induced enhanced neurotrophic responses, characterized by significant cytokine correlations involving brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF) and LIGHT. AAB-induced cytokine levels correlate with clinical symptoms. Further, this study emphasizes a contribution of AAB in PCS, in mitigating long-term immune dysregulation, and a need for therapies modulating IgG-induced pathways.

Source: Alexander Hackel, Franziska Sotzny, Elise Mennenga, Harald Heidecke, Kai Schulze-Foster,  Kontantinos Fourlakis,  Susanne Lueders, Hanna Grasshoff, Kerstin Rubarth, Frank Konietschke, Tanja Lange, Carmen Scheibenbogen, Reza Akbarzade, Gabriela Riemekasten. Autoantibody-Driven Monocyte Dysfunction in Post-COVID Syndrome with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. medRxiv 2025.01.09.25320264; doi: https://doi.org/10.1101/2025.01.09.25320264 https://www.medrxiv.org/content/10.1101/2025.01.09.25320264v1.full.pdf+html (Full text available as PDF file)

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)

Efficacy of repeated immunoadsorption in patients with post-COVID myalgic encephalomyelitis/chronic fatigue syndrome and elevated β2-adrenergic receptor autoantibodies: a prospective cohort study

Abstract:

Background: Since the pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become the leading trigger for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Evidence indicates that autoimmunity plays an important pathophysiological role. We aimed to evaluate the effectiveness of IA treatment in post-COVID ME/CFS patients.

Methods: This pre-post study included 20 post-coronavirus disease 2019 (COVID) ME/CFS patients found to have elevated β2 adrenergic autoantibodies (β2 AR-AB) between October 2022 and October 2023. Patients, with a median disease duration of 22 months (IQR: 15-31), were treated with five immunoadsorption sessions at Charité – Universitätsmedizin Berlin, Germany. Seven were male and 13 female, with a median age of 40 years (IQR: 36-51). The primary end point was the change in the Short Form (36) Health Survey physical functioning domain (SF36 PF) from baseline to four weeks post immunoadsorption. Key symptoms were assessed via questionnaires over six months. Handgrip strength and EndoPAT® measurements were used to evaluate muscle fatigue and vascular dysfunction. Seven patients who worsened after an initial response received a second cycle.

Findings: The treatment was generally well tolerated, reducing total immunoglobulin G by 79% (CI: 73-84%) and β2 AR-AB by 77% (CI: 58-95%). Patients demonstrated a mean increase in the SF36 PF of 17.75 points (CI: 13.41-26.16), with the greatest improvement occurring between months two and three, and significant gains maintained through month six. 14/20 (70%) patients were categorized as responders with an increase in the SF36 PF of ≥ ten points. Further lasting improvements were reported in fatigue, post-exertional malaise, pain, cognitive, autonomic, and immunological symptoms. Female patients had increased repeat handgrip strength at month six.

Interpretation: Immunoadsorption may improve symptoms in post-COVID ME/CFS patients. The beneficial effects of IgG depletion suggest a significant role for autoantibodies and disturbed B-cell function in the condition’s pathophysiology.

Funding: Funded by The Federal Ministry of Education and Research and the Weidenhammer Zöbele Research Foundation.

Source: Stein E, Heindrich C, Wittke K, Kedor C, Rust R, Freitag H, Sotzny F, Krüger A, Tölle M, Grabowski P, Scheibenbogen C, Kim L. Efficacy of repeated immunoadsorption in patients with post-COVID myalgic encephalomyelitis/chronic fatigue syndrome and elevated β2-adrenergic receptor autoantibodies: a prospective cohort study. Lancet Reg Health Eur. 2024 Dec 12;49:101161. doi: 10.1016/j.lanepe.2024.101161. PMID: 39759581; PMCID: PMC11699797. https://pmc.ncbi.nlm.nih.gov/articles/PMC11699797/ (Full text)

Transcriptional reprogramming primes CD8+ T cells toward exhaustion in Myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME) is a severe, debilitating disease, with substantial evidence pointing to immune dysregulation as a key contributor to pathophysiology. To characterize the gene regulatory state underlying T cell dysregulation in ME, we performed multiomic analysis across T cell subsets by integrating single-cell RNA-seq, RNA-seq, and ATAC-seq and further analyzed CD8+ T cell subpopulations following symptom provocation.

Specific subsets of CD8+ T cells, as well as certain innate T cells, displayed the most pronounced dysregulation in ME. We observed upregulation of key transcription factors associated with T cell exhaustion in CD8+ T cell effector memory subsets, as well as an altered chromatin landscape and metabolic reprogramming consistent with an exhausted immune cell state. To validate these observations, we analyzed expression of exhaustion markers using flow cytometry, detecting a higher frequency of exhaustion-associated factors.

Together, these data identify T cell exhaustion as a component of ME, a finding which may provide a basis for future therapies, such as checkpoint blockade, metabolic interventions, or drugs that target chronic viral infections.

Source: Iu DS, Maya J, Vu LT, Fogarty EA, McNairn AJ, Ahmed F, Franconi CJ, Munn PR, Grenier JK, Hanson MR, Grimson A. Transcriptional reprogramming primes CD8+ T cells toward exhaustion in Myalgic encephalomyelitis/chronic fatigue syndrome. Proc Natl Acad Sci U S A. 2024 Dec 10;121(50):e2415119121. doi: 10.1073/pnas.2415119121. Epub 2024 Dec 2. PMID: 39621903. https://www.pnas.org/doi/10.1073/pnas.2415119121 (Full text)

Meta-analysis of natural killer cell cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Reduced natural killer (NK) cell cytotoxicity is the most consistent immune finding in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Meta-analysis of the published literature determined the effect size of the decrement in ME/CFS. Databases were screened for papers comparing NK cell cytotoxicity in ME/CFS and healthy controls. A total of 28 papers and 55 effector:target cell ratio (E:T) data points were collected.

Cytotoxicity in ME/CFS was significantly reduced to about half of healthy control levels, with an overall Hedges’ g of 0.96 (0.75-1.18). Heterogeneity was high but was explained by the range of E:T ratios, different methods, and potential outliers. The outcomes confirm reproducible NK cell dysfunction in ME/CFS and will guide studies using the NK cell model system for pathomechanistic investigations.

Source: Baraniuk JN, Eaton-Fitch N, Marshall-Gradisnik S. Meta-analysis of natural killer cell cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome. Front Immunol. 2024 Oct 17;15:1440643. doi: 10.3389/fimmu.2024.1440643. PMID: 39483457; PMCID: PMC11524851. https://pmc.ncbi.nlm.nih.gov/articles/PMC11524851/ (Full text)

Immune exhaustion in ME/CFS and long COVID

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID are debilitating multisystemic conditions sharing similarities in immune dysregulation and cellular signaling pathways contributing to the pathophysiology. In this study, immune exhaustion gene expression was investigated in participants with ME/CFS or long COVID concurrently.

RNA was extracted from peripheral blood mononuclear cells isolated from participants with ME/CFS (n = 14), participants with long COVID (n = 15), and healthy controls (n = 18). Participants with ME/CFS were included according to Canadian Consensus Criteria. Participants with long COVID were eligible according to the case definition for “Post COVID-19 Condition” published by the World Health Organization. RNA was analyzed using the NanoString nCounter Immune Exhaustion gene expression panel.

Differential gene expression analysis in ME/CFS revealed downregulated IFN signaling and immunoglobulin genes, and this suggested a state of immune suppression. Pathway analysis implicated dysregulated macrophage activation, cytokine production, and immunodeficiency signaling.

Long COVID samples exhibited dysregulated expression of genes regarding antigen presentation, cytokine signaling, and immune activation. Differentially expressed genes were associated with antigen presentation, B cell development, macrophage activation, and cytokine signaling.

This investigation elucidates the intricate role of both adaptive and innate immune dysregulation underlying ME/CFS and long COVID, emphasizing the potential importance of immune exhaustion in disease progression.

Source: Natalie Eaton-Fitch, Penny Rudd, Teagan Er, Livia Hool, Lara Herrero, and Sonya Marshall-Gradisnik. Immune exhaustion in ME/CFS and long COVID. JCI Insight. 2024;9(20):e183810. https://doi.org/10.1172/jci.insight.183810. https://insight.jci.org/articles/view/183810 (Full text)