Causal effects of gut microbiota on risk of interstitial cystitis: a two-sample Mendelian randomization study

The correlation between gut microbiota and interstitial cystitis has garnered significant attention in previous studies. Nevertheless, the causal relationship between them remains to be clarified.

Genetic variation serves as a tool in Mendelian randomization analyses, facilitating the inference of causal relationships between exposure factors and disease outcomes. In this study, summary statistics derived from a comprehensive genome-wide association study conducted by the MiBioGen consortium were utilized as exposure factors, while interstitial cystitis data sourced from the GWAS Catalog served as the disease outcome. Then, a two-sample Mendelian randomization analysis was performed by applying inverse variance-weighted, MR-Egger, Weighted Median, Simple Mode, and Weighted Mode. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis.

IVW results confirmed that genus Haemophilus (OR = 2.20, 95% CI: 1.16-4.15, p = 0.015), genus Butyricimonas (OR = 2.26, 95% CI: 1.15-4.45, p = 0.018), genus Bacteroides (OR = 4.27, 95% CI: 1.36-13.4, p = 0.013) and Coprococcus1 (OR = 3.39, 95% CI: 1.28-8.99, p = 0.014) had a risk effect on interstitial cystitis. Sensitivity analysis did not find outlier SNPs.

Our analysis has identified a causal relationship between specific genera and interstitial cystitis. However, further validation through randomized controlled trials is essential to substantiate these findings.