Tag: review

Inflammation, Autoimmunity, and Infection in Fibromyalgia: A Narrative Review

Abstract:

Fibromyalgia (FM) is a chronic disease characterized by widespread musculoskeletal pain of unknown etiology. The condition is commonly associated with other symptoms, including fatigue, sleep disturbances, cognitive impairment, and depression. For this reason, FM is also referred to as FM syndrome. The nature of the pain is defined as nociplastic according to the latest international classification and is characterized by altered nervous sensitization both centrally and peripherally. Psychosocial conditions have traditionally been considered critical in the genesis of FM. However, recent studies in animal models and humans have provided new evidence in favor of an inflammatory and/or autoimmune pathogenesis.

In support of this hypothesis are epidemiological data of an increased female prevalence, similar to that of autoimmune diseases, and the frequent association with immune-mediated inflammatory disorders. In addition, the observation of an increased incidence of this condition during long COVID revived the hypothesis of an infectious pathogenesis. This narrative review will, therefore, discuss the evidence supporting the immune-mediated pathogenesis of FM in light of the most current data available in the literature.

Source: Paroli M, Gioia C, Accapezzato D, Caccavale R. Inflammation, Autoimmunity, and Infection in Fibromyalgia: A Narrative Review. Int J Mol Sci. 2024 May 29;25(11):5922. doi: 10.3390/ijms25115922. PMID: 38892110; PMCID: PMC11172859. https://pmc.ncbi.nlm.nih.gov/articles/PMC11172859/ (Full text)

Advancing research on regulatory autoantibodies targeting GPCRs: Insights from the 5th international symposium

Abstract:

The 5th International Symposium on Regulatory Autoantibodies Targeting GPCR (RAB-GPCRs) advanced the understanding of the significant role played by autoantibodies targeting G-protein-coupled receptors (GPCRs) in various human diseases. Once considered passive markers, RAB-GPCRs are now recognized as active modulators of cellular signaling, immune regulation, and inflammation.

The symposium highlighted their involvement in multiple prominent pathologies, including autoimmune diseases, cardio- and cerebrovascular diseases, and neuroimmunologic disorders such as myalgic encephalomyelitis/chronic fatigue syndrome and post-COVID-19 syndrome (ME/CFS/PCS), as well as solid organ and hematopoietic stem cell transplantation (SOT/HSCT). Experts from rheumatology, immunology, and neurology presented interdisciplinary discussions on the potential of RAB-GPCRs as biomarkers and therapeutic targets. Advances in screening methods, biomarker identification, and therapeutic strategies were shared, emphasizing their diagnostic potential and application in novel therapeutic interventions.

This report summarizes key insights from the symposium, particularly focusing on the modulatory properties of RAB-GPCRs and their relevance in both immune-mediated diseases and other pathologies (e.g., vascular, degenerative) that are traditionally not considered primarily immune-mediated. Ongoing research is expected to further establish these autoantibodies as crucial components in disease modulation and systems biology contexts, offering new opportunities for precision medicine and improved clinical outcomes in immune-related disorders.

Source: Cabral-Marques O, Schimke LF, Moll G, Filgueiras IS, Nóbile AL, Adri AS, do Vale FYN, Usuda JN, Corrêa YLG, Albuquerque D, Nava RG, Santos RS, Dias HD, Silva HF, Marconi PB, Catar R, Adu-Gyamfi M, Wang P, Khan TA, Hackel AM, Leheis A, Stähle A, Müller A, Schmidt C, Radunovic C, Adjailia EB, Grasshoff H, Humrich JY, Menz J, Fourlakis K, Winziers M, Jäpel M, Wegner MV, Lamprecht P, Nieberding R, Akbarzadeh R, Arnold S, Jendrek S, Klapa S, Augustin S, Biedermann S, Schinke S, Scheerer P, Endres M, Schulze-Forster K, Paul F, Yu X, Sotzny F, Sakmar TP, Banasik M, Haghikia A, Hoffmann MH, Veprintsev D, Witte T, Dalmolin RJS, Ochs HD, Heidecke H, Scheibenbogen C, Shoenfeld Y, Riemekasten G. Advancing research on regulatory autoantibodies targeting GPCRs: Insights from the 5th international symposium. Autoimmun Rev. 2025 Jun 19:103855. doi: 10.1016/j.autrev.2025.103855. Epub ahead of print. PMID: 40543860. https://www.sciencedirect.com/science/article/pii/S1568997225001156 (Full text)

The pivotal role of central sensitization in long COVID, fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Introduction: Long COVID is a condition characterized by persistent unexplained symptoms following COVID-19 infection. These symptoms are not related to another disease or organ damage and are similar to those in fibromyalgia and myslgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Areas covered: The similar clinical and pathophysiological features and management of long COVID, fibromyalgia and ME/CFS are explored from the unifying framework of central sensitivity syndromes. The article is based on a literature search utilizing PubMed for content published between 2021 and 1 May 2025, using search terms: long COVID, long COVID syndrome, post-COVID-19, post-acute SARS-CoV-2, fibromyalgia, ME/CFS, post-exertional malaise and central sensitization.

Expert opinion: Once long COVID is redefined to exclude patients with well-defined organ disease, it fits best as a model of central sensitization. Long COVID is a single syndrome, rather than many distinct diseases. Optimal management of long COVID and similar central sensitivity

Source: Goldenberg DL. The pivotal role of central sensitization in long COVID, fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome. Expert Rev Neurother. 2025 Jun 13:1-17. doi: 10.1080/14737175.2025.2516097. Epub ahead of print. PMID: 40512228. https://www.tandfonline.com/doi/full/10.1080/14737175.2025.2516097

Ignored, dismissed, and minimized: Understanding the harmful consequences of invalidation in health care-A systematic meta-synthesis of qualitative research

Abstract:

The upsurge in the prevalence of contested, ambiguous, and difficult-to-diagnose illnesses presents challenges for clinicians who too often respond by invalidating patients’ symptoms. Although numerous qualitative studies have reported the effects of invalidation on patients’ psychological and behavioral outcomes, this body of research has not been systematically reviewed. Informed by Linehan’s (1993) conceptualization of invalidation, this systematic review elucidated the negative consequences, of symptom invalidation, or the dismissal or minimization of a person’s experiences with illness.

We reviewed 151 qualitative reports representing 11,307 individuals with Ehlers-Danlos syndrome, endometriosis, fibromyalgia syndrome, Gulf War syndrome, irritable bowel syndrome, long COVID, multiple chemical sensitivity, myalgic encephalomyelitis/chronic fatigue syndrome, postural orthostatic tachycardia syndrome, systemic lupus erythematosus, and vulvodynia.

Consistent with Linehan’s theorizing, thematic analysis identified four broad classes of consequences: induced emotional states and beliefs (e.g., shame, suicidality), induced health care emotional states and beliefs (e.g., health care-related anxiety and trauma), induced health care behavior (e.g., health care system avoidance), and diagnostic delay.

Informed by these findings, we developed a novel conceptual model explaining how symptom invalidation leads to these consequences and thereby undermines health outcomes. Future work should explore the proposed conceptual model and identify theoretically informed interventions and policies aimed at preventing symptom invalidation to improve psychological, behavioral, and health outcomes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Source: Bontempo AC, Bontempo JM, Duberstein PR. Ignored, dismissed, and minimized: Understanding the harmful consequences of invalidation in health care-A systematic meta-synthesis of qualitative research. Psychol Bull. 2025 Apr;151(4):399-427. doi: 10.1037/bul0000473. PMID: 40310228. https://psycnet.apa.org/fulltext/2026-10154-001.html (Full text)

Review of Neuroimaging Methods in ME/CFS

Abstract:

The brain is the most complex organ in the human body, and is involved in memory, speech, and movement, as well as regulating the functions of many other organs within the body. Various imaging techniques have detected subtle brain changes in vivo in ME/CFS. This chapter explores different neuroimaging studies used to investigate structural, functional, neurochemical, and tissue microstructural alterations in ME/CFS. These include magnetic resonance imaging (MRI), positron emission tomography (PET), and single photon emission computed tomography (SPECT).

Source: Thapaliya K, Inderyas M, Barnden L. Review of Neuroimaging Methods in ME/CFS. Methods Mol Biol. 2025;2920:257-277. doi: 10.1007/978-1-0716-4498-0_15. PMID: 40372688.  https://link.springer.com/protocol/10.1007/978-1-0716-4498-0_15

The potential therapeutic approaches targeting gut health in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a narrative review

Abstract:

Background: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex disorder characterized by persistent fatigue and cognitive impairments, with emerging evidence highlighting the role of gut health in its pathophysiology. The main objective of this review was to synthesize qualitative and quantitative data from research examining the gut microbiota composition, inflammatory markers, and therapeutic outcomes of interventions targeting the microbiome in the context of ME/CFS.

Methods: The data collection involved a detailed search of peer-reviewed English literature from January 1995 to January 2025, focusing on studies related to the microbiome and ME/CFS. This comprehensive search utilized databases such as PubMed, Scopus, and Web of Science, with keywords including “ME/CFS,” “Gut-Brain Axis,” “Gut Health,” “Intestinal Dysbiosis,” “Microbiome Dysbiosis,” “Pathophysiology,” and “Therapeutic Approaches.” Where possible, insights from clinical trials and observational studies were included to enrich the findings. A narrative synthesis method was also employed to effectively organize and present these findings.

Results: The study found notable changes in the gut microbiota diversity and composition in ME/CFS patients, contributing to systemic inflammation and worsening cognitive and physical impairments. As a result, various microbiome interventions like probiotics, prebiotics, specific diets, supplements, fecal microbiota transplantation, pharmacological interventions, improved sleep, and moderate exercise training are potential therapeutic strategies that merit further exploration.

Conclusions: Interventions focusing on the gut-brain axis may help reduce neuropsychiatric symptoms in ME/CFS by utilizing the benefits of the microbiome. Therefore, identifying beneficial microbiome elements and incorporating their assessments into clinical practice can enhance patient care through personalized treatments. Due to the complexity of ME/CFS, which involves genetic, environmental, and microbial factors, a multidisciplinary approach is also necessary. Since current research lacks comprehensive insights into how gut health might aid ME/CFS treatment, standardized diagnostics and longitudinal studies could foster innovative therapies, potentially improving quality of life and symptom management for those affected.

Source: Hsu CY, Ahmad I, Maya RW, Abass MA, Gupta J, Singh A, Joshi KK, Premkumar J, Sahoo S, Khosravi M. The potential therapeutic approaches targeting gut health in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a narrative review. J Transl Med. 2025 May 11;23(1):530. doi: 10.1186/s12967-025-06527-x. PMID: 40350437. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-025-06527-x (Full text)

Advocating the role of trained immunity in the pathogenesis of ME/CFS: a mini review

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex chronic disease of which the underlying (molecular) mechanisms are mostly unknown. An estimated 0.89% of the global population is affected by ME/CFS. Most patients experience a multitude of symptoms that severely affect their lives. These symptoms include post-exertional malaise, chronic fatigue, sleep disorder, impaired cognitive functions, flu-like symptoms, and chronic immune activation. Therapy focusses on symptom management, as there are no drugs available. Approximately 60% of patients develop ME/CFS following an acute infection.

Such a preceding infection may induce a state of trained immunity; defined as acquired, nonspecific, immunological memory of innate immune cells. Trained immune cells undergo long term epigenetic reprogramming, which leads to changes in chromatin accessibility, metabolism, and results in a hyperresponsive phenotype. Initially, trained immunity has only been demonstrated in peripheral blood monocytes and macrophages. However, more recent findings indicate that hematopoietic stem cells in the bone marrow are required for long-term persistence of trained immunity. While trained immunity is beneficial to combat infections, a disproportionate response may cause disease.

We hypothesize that pronounced hyperresponsiveness of innate immune cells to stimuli could account for the aberrant activation of various immune pathways, thereby contributing to the pathophysiology of ME/CFS. In this mini review, we elaborate on the concept of trained immunity as a factor involved in the pathogenesis of ME/CFS by presenting evidence from other post-infectious diseases with symptoms that closely resemble those of ME/CFS.

Source: Humer B, Dik WA, Versnel MA. Advocating the role of trained immunity in the pathogenesis of ME/CFS: a mini review. Front Immunol. 2025 Mar 25;16:1483764. doi: 10.3389/fimmu.2025.1483764. PMID: 40201181; PMCID: PMC11975576. https://pmc.ncbi.nlm.nih.gov/articles/PMC11975576/ (Full text)

Dysregulation of lipid metabolism, energy production, and oxidative stress in myalgic encephalomyelitis/chronic fatigue syndrome, Gulf War Syndrome and fibromyalgia

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), Gulf War Syndrome (GWS), and Fibromyalgia (FM) are complex, chronic illnesses with overlapping clinical features. Symptoms that are reported across these conditions include post-exertional malaise (PEM), fatigue, and pain, yet the etiology of these illnesses remains largely unknown. Diagnosis is challenging in patients with these conditions as definitive biomarkers are lacking; patients are required to meet clinical criteria and often undergo lengthy testing to exclude other conditions, a process that is often prolonged, costly, and burdensome for patients.

The identification of reliable validated biomarkers could facilitate earlier and more accurate diagnosis and drive the development of targeted pharmacological therapies that might address the underlying pathophysiology of these diseases. Major driving forces for biomarker identification are the advancing fields of metabolomics and proteomics that allow for comprehensive characterization of metabolites and proteins in biological specimens. Recent technological developments in these areas enable high-throughput analysis of thousands of metabolites and proteins from a variety of biological samples and model systems, that provides a powerful approach to unraveling the metabolic phenotypes associated with these complex diseases.

Emerging evidence suggests that ME/CFS, GWS, and FM are all characterized by disturbances in metabolic pathways, particularly those related to energy production, lipid metabolism, and oxidative stress. Altered levels of key metabolites in these pathways have been reported in studies highlighting potential common biochemical abnormalities. The precise mechanisms driving altered metabolic pathways in ME/CFS, GWS, and FM remain to be elucidated; however, the elevated oxidative stress observed across these illnesses may contribute to symptoms and offer a potential target for therapeutic intervention.

Investigating the mechanisms, and their role in the disease process, could provide insights into disease pathogenesis and reveal novel treatment targets. As such, comprehensive metabolomic and proteomic analyses are crucial for advancing the understanding of these conditions in-order to identify both common, and unique, metabolic alterations that could serve as diagnostic markers or therapeutic targets.

Source: Davis L, Higgs M, Snaith A, Lodge TA, Strong J, Espejo-Oltra JA, Kujawski S, Zalewski P, Pretorius E, Hoerger M, Morten KJ. Dysregulation of lipid metabolism, energy production, and oxidative stress in myalgic encephalomyelitis/chronic fatigue syndrome, Gulf War Syndrome and fibromyalgia. Front Neurosci. 2025 Mar 10;19:1498981. doi: 10.3389/fnins.2025.1498981. PMID: 40129725; PMCID: PMC11931034. https://pmc.ncbi.nlm.nih.gov/articles/PMC11931034/ (Full text)

Unravelling the Connection Between Energy Metabolism and Immune Senescence/Exhaustion in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating disease, characterized by a diverse array of symptoms including post-exertional malaise (PEM), severe fatigue, and cognitive impairments, all of which drastically diminish the patients’ quality of life. Despite its impact, no curative treatments exist, largely due to the limited understanding of the disease’s underlying pathophysiology.
Mitochondrial dysfunction, leading to impaired energy production and utilization, is believed to play a key role in the onset of fatigue and PEM, positioning it as a potential key pathophysiological mechanism underlying ME/CFS. Additionally, the disorder shows similarities to chronic viral infections, with frequent reports of immune system alterations, suggesting a critical role for immune (dys)functioning. In particular, the roles of immune senescence and immune exhaustion—two fundamental immune states—remain poorly understood in ME/CFS.
This state-of-the-art review explores how metabolic dysfunction and immune dysfunction may be interconnected in ME/CFS, proposing that energy deficits may directly impair immune function. By examining this metabolic–immune interplay, this review highlights potential pathways for developing innovative therapeutic strategies that target both energy metabolism and immune regulation, offering hope for improving patient outcomes.
Source: Van Campenhout J, Buntinx Y, Xiong H-Y, Wyns A, Polli A, Nijs J, Aerts JL, Laeremans T, Hendrix J. Unravelling the Connection Between Energy Metabolism and Immune Senescence/Exhaustion in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Biomolecules. 2025; 15(3):357. https://doi.org/10.3390/biom15030357 https://www.mdpi.com/2218-273X/15/3/357 (Full text)

Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

ME/CFS is a debilitating multisystem disorder of unclear etiology that affects many individuals worldwide. One of its hallmark symptoms is prolonged fatigue following exertion, a feature also observed in long COVID, suggesting an underlying dysfunction in energy production in both conditions. Here, mitochondrial dysfunction and its potential pathogenetic role in these disorders are reviewed.

Source: Syed AM, Karius AK, Ma J, Wang PY, Hwang PM. Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Physiology (Bethesda). 2025 Feb 17. doi: 10.1152/physiol.00056.2024. Epub ahead of print. PMID: 39960432. https://journals.physiology.org/doi/abs/10.1152/physiol.00056.2024 (Full text available as PDF file)