Venous Thromboembolism and Gut Dysbiosis: Mechanistic Links Between Endotoxemia, Microbial Metabolites, and Thromboinflammation

Background: Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is increasingly recognized as a thromboinflammatory disorder involving coagulation, innate immunity, endothelial dysfunction, and vascular homeostasis. Emerging evidence suggests that gut microbiome-related inflammatory and metabolic signals may influence pathways potentially relevant to VTE through intestinal barrier dysfunction, microbial translocation, and microbiome-derived metabolites. This review critically examines the direct and indirect evidence relating gut dysbiosis to mechanisms potentially relevant to venous thrombogenesis. Methods: A structured literature search of PubMed, Scopus, and Web of Science was conducted from database inception to February 2026. Observational, translational, experimental, preclinical, and selected genetic studies were narratively synthesized across heterogeneous evidence types. Results: Available evidence suggests that intestinal barrier dysfunction and microbial translocation may increase systemic exposure to lipopolysaccharide and other microbial products, potentially contributing to inflammatory signaling and procoagulant responses. Proposed downstream effects include tissue factor (TF) activation, platelet reactivity, neutrophil extracellular traps (NETs) formation, complement signaling, endothelial perturbation, and impaired balance of anticoagulant and fibrinolytic pathways. Microbiome-derived metabolites, including trimethylamine N-oxide (TMAO), phenylacetylglutamine (PAGln), bile acids, and short-chain fatty acids (SCFAs), have been linked, mainly in experimental or non-VTE settings, to thrombosis-related biology. However, most evidence remains indirect, associative, or experimental, whereas direct human VTE-specific evidence is limited and heterogeneous. Conclusions: The gut microbiome–VTE axis is biologically plausible and supported mainly by mechanistic and indirect evidence, but current data are insufficient to support strong causal conclusions. Further longitudinal, well-phenotyped, mechanistically informed studies are needed to determine whether microbiome-related pathways have measurable clinical relevance in human VTE.