Microbial involvement in myalgic encephalomyelitis/chronic fatigue syndrome pathophysiology

Abstract

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and disabling disease related to persistent fatigue, exercise intolerance, post-exertional malaise, cognitive dysfunction, and musculoskeletal/joint pain. Gastrointestinal comorbidities, including irritable bowel syndrome, have been reported in affected individuals, indicating a potential role of gut microbiota in disease progression. In this paper, bacterial and metabolomic dysbiosis in subjects with ME/CFS are reviewed, and phenotypic, microbial, and metabolic biomarkers specific to individual cohorts are also identified. Furthermore, microbiome fluctuations or metabolic endotoxemia are proposed as possible disorder biomarkers. Based on the fact that gut microbiota dysbiosis reverts to a state of eubiosis in long-term patients with this condition, it may be hypothesized that disease progression begins with the loss of beneficial gut microorganisms, particularly short-chain fatty acid producers, leading to more widespread gastrointestinal phenotypes that are subsequently reflected in plasma metabolite levels. These alterations, specific of each individual, thereby result in metabolic and phenotypic shifts and in ME/CFS.