Tag: gut flora

Comparative Gut Microbiome Alterations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome & Long COVID-19 Syndrome

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID-19 syndrome (LC) show substantial clinical overlap, but direct comparative microbiome studies remain limited.
Methods: In this cross-sectional study, we compared the fecal gut microbiome of patients with ME/CFS, LC, and healthy controls (HC) within a unified analytical framework using 16S rRNA profiling, differential abundance testing, and multivariate modeling. We also examined associations between microbiome variation and questionnaire-derived symptom-domain scores.
Results: Alpha-diversity did not differ significantly among groups, whereas beta-diversity analyses showed small but significant disease-associated community differences with broad overlap between cohorts. Differential abundance analysis identified stronger signals in disease-versus-control contrasts than in the direct ME/CFS vs. LC contrast. Both ME/CFS and LC shared enrichment of Sutterella and depletion of Terrisporobacter and Lachnospiraceae relative to HC. Predicted functional profiling showed shared disease-versus-control changes in pathways related to anaerobic acetate/H2 carbon flow, inositol/polyol degradation, phosphonate/C1-related metabolism, and lysine-derived fermentation. Regression analyses showed the strongest microbiome associations with fatigue-related and physiosomatic domains, while affective, cognitive, and gastrointestinal outcomes showed weaker signals.
Conclusions: Overall, these findings support the presence of overlapping but non-identical gut microbiome alterations in ME/CFS and LC. The results provide a basis for future longitudinal and multi-omics studies aimed at clarifying the stability, functional relevance, and clinical utility of these microbial patterns.
Source: Donchev D, Nikolova R, Vaseva K, Taskov H, Murdjeva M, Maes M, Ivanov IN. Comparative Gut Microbiome Alterations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID-19 Syndrome. Biomedicines. 2026; 14(6):1183. https://doi.org/10.3390/biomedicines14061183 https://www.mdpi.com/2227-9059/14/6/1183 (Full text available as PDF file)

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 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)

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)

The Microbiota-Gut-Brain Axis in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Narrative Review of an Emerging Field

Abstract:

The intricate relationship between gut microbiota and the brain has emerged as a pivotal area of research, particularly in understanding myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This complex condition is characterized by debilitating fatigue, cognitive dysfunction, and a wide array of systemic manifestations, posing significant challenges for diagnosis and treatment. Recent studies highlight the microbiota-gut-brain axis as a crucial pathway in ME/CFS pathophysiology, suggesting that alterations in gut microbial composition may impact immune responses, neurochemical signaling, and neuronal health.

This narrative review systematically explores English-language scholarly articles from January 1995 to January 2025, utilizing databases such as PubMed, Scopus, and Web of Science. The findings underscore the potential for targeted therapeutic interventions aimed at correcting gut dysbiosis. As research progresses, a deeper understanding of the microbiota-gut-brain connection could lead to innovative approaches for managing ME/CFS, ultimately enhancing the quality of life for affected individuals.

Source: El-Sehrawy AAMA, Ayoub II, Uthirapathy S, Ballal S, Gabble BC, Singh A, V K, Panigrahi R, Kamali M, Khosravi M. The Microbiota-Gut-Brain Axis in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Narrative Review of an Emerging Field. Eur J Transl Myol. 2025 Feb 12. doi: 10.4081/ejtm.2025.13690. Epub ahead of print. PMID: 39937103. https://pubmed.ncbi.nlm.nih.gov/39937103/