A Mendelian Randomization Study: Roles of Gut Microbiota in Sepsis – Who is the Angle?

Gut microbiota (GM) is a crucial underlying player during sepsis pathogenesis. However, the causal relationship is unclear and remains to be determined. A two-sample Mendelian randomization study was implemented. The statistical data about sepsis together with GM summarized from genome-wide association studies were evaluated. Instrumental variables were defined as single-nucleotide polymorphisms with prominent correlations with exposure. The inverse-variance-weighted test was employed as a major approach of Mendelian randomization analysis to estimate of causal relationships. The inverse-variance-weighted analysis results demonstrated that at different taxa levels, Actinobacteria and Bifidobacteriaceae influence sepsis. Actinobacteria had negative relationships to sepsis risk at the phylum (β = –0.34, SE = 0.10, p = 0.0008) and class (β = –0.23, SE = 0.07, p = 0.0011) levels in outcome coded ieu-b-69. Actinobacteria at the phylum level (β = –0.22, SE = 0.10, p = 0.027) was also negatively associated with sepsis in outcome coded ieu-b-4980. Bifidobacteriaceae at the order (β = –0.20, SE = 0.06, p = 0.0021), family (β = –0.20, SE = 0.06, p = 0.0021), and genus (β = –0.20, SE = 0.06, p = 0.0007) levels were all negatively correlated with the risk of sepsis in outcome coded ieu-b-69. The results of the Wald ratio model showed that Tyzzerella genus (OR (95%CI) = 0.6902[0.4907,0.9708], p = 0.0331) and Gastranaerophilales order (OR (95%CI) = 0.5907[0.3516,0.9926], p = 0.0468) were negatively connected with sepsis. This study implied at different taxa levels Actinobacteria and Bifidobacteriaceae, Tyzzerella genus, and Gastranaerophilales order have a causal relationship with sepsis, indicating that they are protective factors for the incidence of sepsis.