Gut microbiota, skin microbiota, and alopecia areata: A Mendelian randomization study

Abstract

Background: Observational studies have shown an association between skin microbiota and alopecia areata (AA), but the causal connection remains ambiguous. Methods: We obtained data on skin microbiota and AA from summary statistics of Genome-Wide Association Studies and applied statistical methods from Mendelian randomization (MR) to assess causal relationships. Additionally, we investigated whether the skin microbiota acts as a mediator in the pathway from gut microbiota to AA. Results: In the MR analysis of KORA FF4 and AA, the inverse-variance weighting method indicated that Corynebacterium (odds ratio [OR] = 0.82, 95% confidence interval [CI]: 0.70–0.96, p = 0.02) and asv037 (OR = 0.87, 95% CI: 0.76–0.99, p = 0.05) exerted protective effects, while Betaproteobacteria (OR = 1.21, 95% CI: 1.01–1.44, p = 0.03), asv015 (OR = 1.27, 95% CI: 1.05–1.54, p = 0.02), and Burkholderiales (OR = 1.20, 95% CI: 1.04–1.38, p = 0.01) were identified as risk factors in AA. In the MR analysis of PopGen and AA, asv001 (OR = 1.12, 95% CI: 1.01–1.24, p = 0.04), asv054 (OR = 1.13, 95% CI: 1.01–1.25, p = 0.03), and asv059 (OR = 1.14, 95% CI: 1.02–1.27, p = 0.02) were found to potentially increase the risk in AA. Furthermore, in the influence of gut microbiota on AA, the skin microbiota did not act as a mediator. Conclusion: Our analysis suggests potential causal relationships between certain skin microbiota and AA, revealing insights into its pathogenesis and potential intervention strategies.