Causal relationship in gut microbiota and Sjogren's syndrome using Mendelian randomization.

Background: A growing number of observational studies have found that gut microbiota is associated with a higher risk of Sjogren's syndrome. However, the relationship between the two remains to be further determined. Methods: : We conducted a two-sample Mendelian randomization analysis to determine whether the gut microbiota is causally related to Sjogren’s syndrome. As exposure factors, we used summary statistics from an 18340-person genome-wide association study of the gut microbiome published by MiBioGen consortium, and data from the Finn Gen GWAS of Sjogren's syndrome, with 2495 patients; 414,262 controls were included as disease outcomes.Two-sample Mendelian randomization analysis was subsequently performed by inverse variance-weighted, MR-Egger, and weighted median. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis. Results: IVW results confirmed that genus Ruminiclostridium9 (OR = 0.727, 95%CI: 0.536-0.986, P = 0.040),f family Victivallaceae(OR = 0.865, 95%CI: 0.750-0.999, P =0.048), while genus Butyricicoccus (OR=1.516, 95%CI: 1.089-2.111, P = 0.014), genus Eubacterium coprostanoligenes group(OR =1.542, 95%CI: 1.085-2.192, P =0.016), amily Porphyromonadaceae (OR = 1.549, 95%CI: 1.068-2.246 P = 0.021), while phylum Cyanobacteria (OR = 10272, 95%CI: 1.020-1.586, P = 0.033) had the opposite effect. No abnormal SNPS were found in a sensitivity analysis. Conclusion: We have found some causal relationships between gut microbiota and Sjogren's syndrome. However, further randomized controlled trials are needed.