Implications of Gut Microbiome in Fibromyalgia: A Scoping Review.

Introduction: Fibromyalgia (FM) is a chronic pain syndrome marked by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive dysfunction. Despite extensive research, its pathophysiology remains unclear. Emerging evidence implicates the gut microbiome (GMB) in FM through mechanisms involving pain modulation, immune dysregulation, and neuroinflammation. This review explores the role of gut dysbiosis in FM pathogenesis, focusing on microbial alterations, immune interactions, intestinal permeability, and neurochemical pathways. Materials and Methods: A systematic search of PubMed, Scopus, and Web of Science was conducted to identify studies published in the last two decades examining the relationship between GMB and FM. Inclusion criteria encompassed original research, systematic reviews, and meta-analyses addressing microbial dysbiosis, immune modulation, and neurochemical alterations in FM. Studies focused solely on treatment interventions were excluded. A narrative synthesis approach was used to integrate findings and highlight mechanistic insights. Results: FM patients exhibit significant gut microbial dysbiosis, including reduced butyrate-producing bacteria and increased pro-inflammatory species. These alterations are associated with compromised intestinal barrier integrity, systemic immune activation, and elevated pro-inflammatory cytokines. Neurochemical disruptions include serotonin deficiency, gamma-aminobutyric acid/glutamate imbalance, and reduced short-chain fatty acids, contributing to central sensitization and neuroinflammation. Dysregulation of the gut-brain axis and microbial metabolite pathways further exacerbate FM symptoms. Conclusion: GMB dysbiosis plays a pivotal role in FM pathogenesis through immune activation, intestinal permeability changes, and neurochemical modulation. Understanding these mechanisms may inform future research into microbiome-based biomarkers and therapeutic strategies. While treatment implications are beyond the scope of this review, the findings underscore the potential of targeting microbial pathways in FM management.