Tag: microbiome

Gut Microbiome and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Insights into Disease Mechanisms

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling clinical condition, whose hallmark characteristic is post-exertional malaise (PEM). It can affect many organs and systems, leading to severe impairment of patients’ quality of life. Although numerous post-infectious, immunological, neurological, metabolic, and endocrine alterations have been documented, neither a definitive diagnostic marker nor approved treatments are available. The etiology and pathophysiology remain incompletely understood; however, emerging evidence suggests that the gut microbiome plays a role in immune responses and the development of ME/CFS.

It is hypothesized that specific disturbances in gut microbiome composition, known as dysbiosis, may compromise the integrity of the intestinal barrier. This consequently leads to translocation of microbial components, which further triggers an immune response and systemic inflammation complicating the clinical presentation of ME/CFS. Furthermore, in terms of the so-called gut-brain axis, microbiome changes may lead to distinct neurocognitive impairments observed in ME/CFS patients.

This review offers the readers a broad perspective on the topic on ME/CFS, with a particular emphasis on the interplay between the gut microbiome and disease mechanisms. Last but not least, recent data on potential treatment strategies for intestinal dysbiosis in ME/CFS patients have been included.

Source: Nikolova R, Donchev D, Vaseva K, Ivanov IN. Gut Microbiome and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Insights into Disease Mechanisms. Int J Mol Sci. 2025 Dec 31;27(1):425. doi: 10.3390/ijms27010425. PMID: 41516296; PMCID: PMC12785659. https://pmc.ncbi.nlm.nih.gov/articles/PMC12785659/ (Full text)

Alterations in gut microbiota and associated metabolites in patients with chronic fatigue syndrome

Abstract:

To investigate differences in gut microbiota composition and short-chain fatty acids (SCFAs) metabolism between patients with Chronic Fatigue Syndrome (CFS) and Healthy Controls (HC), and to explore their associations with the CFS pathogenesis. This case-control study included 80 subjects, comprising 40 patients with CFS and 40 age- and sex-matched HC.

Fecal microbial community structure was analyzed using 16S rRNA gene high-throughput sequencing. Fecal SCFAs concentrations were quantified using Gas Chromatography-Mass Spectrometry (GC-MS). Spearman correlation analysis with false discovery rate (FDR) adjustment was performed to elucidate associations among gut microbiota, SCFAs, and clinical scores.

Compared to the HC group, the CFS group exhibited reduced gut microbiota α-diversity (e.g., ACE, Chao1, Shannon indices, all P < 0.01) and significantly altered β-diversity (ADONIS, P = 0.006). After FDR adjustment, fecal levels of acetate, butyrate, isobutyrate, and isovalerate remained significantly lower in the CFS group (all q < 0.05). Differential abundance analysis revealed a significant reduction in key taxa including the phylum Firmicutes (q = 0.010), class Verrucomicrobiae (q = 0.038), order Clostridiales (q = 0.043), and families Rikenellaceae (q = 0.011) and Ruminococcaceae (q = 0.049). Spearman correlation analysis solidified functional connections: key SCFA-producing taxa (e.g., Faecalibacterium, Subdoligranulum, Ruminococcaceae) were positively correlated with butyrate levels (r = 0.52-0.56, all q < 0.05).

Furthermore, reduced abundances of Rikenellaceae and Alistipes were associated with lower SF-36 scores (r = 0.26, q = 0.032) and higher fatigue scores (FSS/FS-14, r = – 0.28 to – 0.30, q < 0.05). Isovalerate levels were negatively correlated with FS-14 scores (r = – 0.307, q = 0.014). Among CFS patients, those with higher dietary fiber intake had significantly higher levels of acetate and isovalerate than those with lower intake (both q < 0.05).

Patients with CFS exhibit significant gut dysbiosis and abnormal SCFA metabolism. The reduction in key SCFA-producing taxa, their positive correlations with SCFAs levels, and the negative correlations of both with fatigue severity solidify a functional link between gut microbial depletion, reduced SCFAs, and clinical symptoms in CFS. Higher dietary fiber intake may partially ameliorate SCFAs metabolic disturbances in CFS patients.

Source: Cheng X, Wang W, Xu T, Wang Y, Zhen X, Man W, Gao S, Yin Y. Alterations in gut microbiota and associated metabolites in patients with chronic fatigue syndrome. Sci Rep. 2025 Dec 12;15(1):43681. doi: 10.1038/s41598-025-27564-y. PMID: 41387992; PMCID: PMC12700865. https://pmc.ncbi.nlm.nih.gov/articles/PMC12700865/ (Full text)

The Gut-Brain-Immune Axis in Environmental Sensitivity Illnesses: Microbiome-Centered Narrative Review of Fibromyalgia Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, and Multiple Chemical Sensitivity

Abstract:

Environmental sensitivity illnesses-including fibromyalgia syndrome (FMS), myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and multiple chemical sensitivity (MCS)-are chronic, disabling disorders characterized by hypersensitivity to environmental stimuli, persistent fatigue, widespread pain, and neurocognitive and autonomic dysfunction. Although their diagnostic criteria differ, increasing evidence suggests overlapping clinical features and shared biological mechanisms. A unifying hypothesis highlights the gut-brain-immune axis, where alterations in the intestinal microbiome, epithelial barrier dysfunction, and aberrant immune signaling interact with central sensitization and systemic metabolic dysregulation.

Recent studies demonstrate reduced microbial diversity, depletion of anti-inflammatory taxa (e.g., Faecalibacterium prausnitzii, Bifidobacterium), and enrichment of pro-inflammatory Clostridium species across these conditions. These shifts likely alter production of short-chain fatty acids, amino acid metabolites, and complex lipids, with downstream effects on mitochondrial function, neuroinflammation, and host energy metabolism. Moreover, emerging clinical interventions-including probiotics, prebiotics, synbiotics, and fecal microbiota transplantation-suggest a potential role for microbiome-targeted therapies, though controlled evidence remains limited.

This review synthesizes current knowledge on microbiome alterations in FMS, ME/CFS, and MCS, emphasizing their convergence on metabolic and immune pathways. By integrating microbial, immunological, and neurophysiological perspectives, we propose a microbiome-centered framework for understanding environmental sensitivity illnesses and highlight avenues for translational research and therapeutic innovation.

Source: Watai K, Taniguchi M, Azuma K. The Gut-Brain-Immune Axis in Environmental Sensitivity Illnesses: Microbiome-Centered Narrative Review of Fibromyalgia Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, and Multiple Chemical Sensitivity. Int J Mol Sci. 2025 Oct 14;26(20):9997. doi: 10.3390/ijms26209997. PMID: 41155291. https://www.mdpi.com/1422-0067/26/20/9997 (Full text)

The gut microbial composition is different in chronic fatigue syndrome than in healthy controls

Abstract:

The pathogenesis of Chronic Fatigue Syndrome (CFS) is yet unknown. This study aimed to assess the gut microbial composition in CFS patients versus in healthy controls (HCs).

The composition of fecal bacteria was examined in twenty-five CFS patients and sixteen HCs using Illumina sequencing of 16 S rRNA gene amplicons targeting the V3-V4 bacterial gene regions. 143 (46%) of the microbial genera were found only in the CFS. In addition, the gut microbial composition in the CFS patients contained a much higher proportion of the 10 most commonly found bacteria compared to the HCs group. A significantly lower observed number of operational taxonomic units (OTUs) was noted in CFS compared to HCs (p = 0.045).

Significant between-group differences in the gut microbial composition in CFS compared to HCs were noted. The three most discriminating Amplicon Sequencing Variants (ASVs): ASV 191, ASV 44, and ASV 75, were identified as significantly more abundant in the healthy control group compared to the patient group. In addition, the Neural Network (multilayer perceptron) was able to discriminate gut microbial composition from CFS versus HCs with excellent performance (AUC = 0.935).

The gut microbial composition is different in CFS patients compared to HCs. Further studies should assess the pathophysiological consequences of these differences as well as the effectiveness of therapies aimed at modifying the gut microbial composition in CFS patients.

Source: Prylińska-Jaśkowiak M, Tabisz H, Kujawski S, Godlewska BR, Słomko J, Januszko-Giergielewicz B, Murovska M, Morten KJ, Sokołowski Ł, Zalewski P. The gut microbial composition is different in chronic fatigue syndrome than in healthy controls. Sci Rep. 2025 Sep 26;15(1):33075. doi: 10.1038/s41598-025-16438-y. PMID: 41006438. https://www.nature.com/articles/s41598-025-16438-y (Full text)

Advancing Digital Precision Medicine for Chronic Fatigue Syndrome through Longitudinal Large-Scale Multi-Modal Biological Omics Modeling with Machine Learning and Artificial Intelligence

Abstract:

We studied a generalized question: chronic diseases like ME/CFS and long COVID exhibit high heterogeneity with multifactorial etiology and progression, complicating diagnosis and treatment. To address this, we developed BioMapAI, an explainable Deep Learning framework using the richest longitudinal multi-omics dataset for ME/CFS to date.

This dataset includes gut metagenomics, plasma metabolome, immune profiling, blood labs, and clinical symptoms. By connecting multi-omics to a symptom matrix, BioMapAI identified both disease- and symptom-specific biomarkers, reconstructed symptoms, and achieved state-of-the-art precision in disease classification.

We also created the first connectivity map of these omics in both healthy and disease states and revealed how microbiome-immune-metabolome crosstalk shifted from healthy to ME/CFS.

Source: Xiong R. Advancing Digital Precision Medicine for Chronic Fatigue Syndrome through Longitudinal Large-Scale Multi-Modal Biological Omics Modeling with Machine Learning and Artificial Intelligence. ArXiv [Preprint]. 2025 Jun 18:arXiv:2506.15761v1. PMID: 40980765; PMCID: PMC12447721. https://pmc.ncbi.nlm.nih.gov/articles/PMC12447721/ (Full text available as PDF file)

AI-driven multi-omics modeling of myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic illness with a multifactorial etiology and heterogeneous symptomatology, posing major challenges for diagnosis and treatment. Here we present BioMapAI, a supervised deep neural network trained on a 4-year, longitudinal, multi-omics dataset from 249 participants, which integrates gut metagenomics, plasma metabolomics, immune cell profiling, blood laboratory data and detailed clinical symptoms.

By simultaneously modeling these diverse data types to predict clinical severity, BioMapAI identifies disease- and symptom-specific biomarkers and classifies ME/CFS in both held-out and independent external cohorts. Using an explainable AI approach, we construct a unique connectivity map spanning the microbiome, immune system and plasma metabolome in health and ME/CFS adjusted for age, gender and additional clinical factors.

This map uncovers altered associations between microbial metabolism (for example, short-chain fatty acids, branched-chain amino acids, tryptophan, benzoate), plasma lipids and bile acids, and heightened inflammatory responses in mucosal and inflammatory T cell subsets (MAIT, γδT) secreting IFN-γ and GzA.

Overall, BioMapAI provides unprecedented systems-level insights into ME/CFS, refining existing hypotheses and hypothesizing unique mechanisms—specifically, how multi-omics dynamics are associated to the disease’s heterogeneous symptoms.

Source: Xiong, R., Aiken, E., Caldwell, R. et al. AI-driven multi-omics modeling of myalgic encephalomyelitis/chronic fatigue syndrome. Nat Med (2025). https://doi.org/10.1038/s41591-025-03788-3  https://www.nature.com/articles/s41591-025-03788-3

Immune Signatures in Post-Acute Sequelae of COVID-19 (PASC) and Myalgia/Chronic Fatigue Syndrome (ME/CFS): Insights from the Fecal Microbiome and Serum Cytokine Profiles

Abstract:

While there are many postulates for the etiology of post-viral chronic fatigue and other symptomatology, little is known. We draw on our past experience of these syndromes to devise means which can expose the primary players of this malady in terms of a panoply participating biomolecules and the state of the stool microbiome.
Using databases established from a large dataset of patients at risk of colorectal cancer who were followed longitudinally over 3 decades, and a smaller database dedicated to building a Long PASC cohort (Post-Acute Sequelae of COVID-19), we were able to ascertain factors that predisposed patients to (and resulted in) significant changes in various biomarkers, i.e., the stool microbiome and serum cytokine levels, which we verified by collecting stool and serum samples.
There were significant changes in the stool microbiome with an inversion from the usual Bacillota and Bacteroidota species. Serum cytokines showed significant differences in MIP-1β versus TARC (CC chemokine ligand 17) in patients with either PASC or COVID-19 (p < 0.02); IL10 versus IL-12p70a (p < 0.02); IL-1b versus IL-6 (p < 0.01); MCP1 versus TARC (p < 0.03); IL-8 versus TARC (p < 0.002); and Eotaxin3 versus TARC (p < 0.004) in PASC. Some changes were seen solely in COVID-19, including MDC versus MIP-1α (p < 0.01); TNF-α versus IL-1-β (p < 0.06); MCP4 versus TARC (p < 0.0001). We also show correlates with chronic fatigue where an etiology was not identified.
These findings in patients with positive criteria for PASC show profound changes in the microbiome and serum cytokine expression. Patients with chronic fatigue without clear viral etiologies also have common associations, including a history of tonsillectomy, which evokes a likely immune etiology.
Source: Tobi, M., Chaudhari, D., Ryan, E. P., Rossi, N. F., Koka, O., Baxter, B., Tipton, M., Dutt, T. S., Tobi, Y., McVicker, B., & Angoa-Perez, M. (2025). Immune Signatures in Post-Acute Sequelae of COVID-19 (PASC) and Myalgia/Chronic Fatigue Syndrome (ME/CFS): Insights from the Fecal Microbiome and Serum Cytokine Profiles. Biomolecules, 15(7), 928. https://doi.org/10.3390/biom15070928 https://www.mdpi.com/2218-273X/15/7/928 (Full text)

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)

The gut microbiota promotes pain in fibromyalgia

Highlights:

• Transplanting gut microbiota from women with fibromyalgia into mice induces pain
• It also induces immune activation, metabolomic changes, and reduced skin innervation
• Gut microbiota promotes pain through several mechanisms
Summary:

Fibromyalgia is a prevalent syndrome characterized by widespread pain in the absence of evident tissue injury or pathology, making it one of the most mysterious chronic pain conditions. The composition of the gut microbiota in individuals with fibromyalgia differs from that of healthy controls, but its functional role in the syndrome is unknown. Here, we show that fecal microbiota transplantation from fibromyalgia patients, but not from healthy controls, into germ-free mice induces pain and numerous molecular phenotypes that parallel known changes in fibromyalgia patients, including immune activation and metabolomic profile alterations. Replacing the fibromyalgia microbiota with a healthy microbiota substantially alleviated pain in mice. An open-label trial in women with fibromyalgia (Registry MOH_2021-11-04_010374) showed that transplantation of a healthy microbiota is associated with reduced pain and improved quality of life. We conclude that altered gut microbiota has a role in fibromyalgia pain, highlighting it as a promising target for therapeutic interventions.
Source: Cai W, Haddad M, Haddad R, Kesten I, Hoffman T, Laan R, Westfall S, Defaye M, Abdullah NS, Wong C, Brown N, Tansley S, Lister KC, Hooshmandi M, Wang F, Lorenzo LE, Hovhannisyan V, Ho-Tieng D, Kumar V, Sharif B, Thurairajah B, Fan J, Sahar T, Clayton C, Wu N, Zhang J, Bar-Yoseph H, Pitashny M, Krock E, Mogil JS, Prager-Khoutorsky M, Séguéla P, Altier C, King IL, De Koninck Y, Brereton NJB, Gonzalez E, Shir Y, Minerbi A, Khoutorsky A. The gut microbiota promotes pain in fibromyalgia. Neuron. 2025 Apr 18:S0896-6273(25)00252-1. doi: 10.1016/j.neuron.2025.03.032. Epub ahead of print. PMID: 40280127. https://www.cell.com/neuron/fulltext/S0896-6273(25)00252-1 (Full text)

Beyond acute infection: mechanisms underlying post-acute sequelae of COVID-19 (PASC)

Summary:

  • Immune dysregulation is a key aspect of post-acute sequelae of coronavirus disease 2019 (PASC), also known as long COVID, with sustained activation of immune cells, T cell exhaustion, skewed B cell profiles, and disrupted immune communication thereby resulting in autoimmune-related complications.
  • The gut is emerging as a critical link between microbiota, metabolism and overall dysfunction, potentially sharing similarities with other chronic fatigue conditions and PASC.
  • Immunothrombosis and neurological signalling dysfunction emphasise the complex interplay between the immune system, blood clotting, and the central nervous system in the context of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
  • Clear research gaps in the design of PASC studies, especially in the context of longitudinal research, stand out as significant areas of concern.

Source: Adhikari, A., Maddumage, J., Eriksson, E.M., Annesley, S.J., Lawson, V.A., Bryant, V.L. and Gras, S. (2024), Beyond acute infection: mechanisms underlying post-acute sequelae of COVID-19 (PASC). Med J Aust, 221: S40-S48. https://doi.org/10.5694/mja2.52456 https://onlinelibrary.wiley.com/doi/full/10.5694/mja2.52456 (Full text)