Gut Microbiota and Its Association with Alopecia Areata: Insights from a Two-Sample Mendelian Randomization Study

Abstract

Abstract Background Recent cross-sectional analyses have disclosed associations between gut microbiota diversity and alopecia areata (AA). However, the definitive causal influence of gut microbiota on AA remains undetermined. Methods To probe the potential causal association between gut microbiota and AA, we leveraged data from Genome-wide association studies (GWAS) conducted by both the MiBioGen and FinnGen consortiums. The dataset included information on gut microbiota (n = 13,266) and AA (n = 211,428), extracted from earlier observational studies. We applied five statistical techniques in our Mendelian randomization (MR) analysis to infer the causality between gut microbiota and AA. Conversely, we undertook a reverse MR analysis to ascertain whether AA causally impacts gut microbiota. The validity of the MR analysis was evaluated via sensitivity analysis. Results The IVW assessment implied a protective influence against AA from Butyricimonas (OR = 0.37, 95% CI: 0.18–0.77, p = 0.01), Enterorhabdus (OR = 0.40, 95% CI: 0.16–0.95, p = 0.04), Eubacterium (xylanophilum group) (OR = 0.36, 95% CI: 0.15–0.84, p = 0.02), and Phascolarctobacterium (OR = 0.37, 95% CI: 0.15–0.91, p = 0.03). In contrast, Ruminococcaceae UCG003 emerged as a risk factor for AA (OR = 2.79, 95% CI: 1.27–6.14, p = 0.01). Our reverse MR exploration did not discern any statistically significant causal association between AA and gut microbiota. Similarly, no significant heterogeneity of IVs or horizontal pleiotropy was observed. Conclusions This current study offers compelling evidence for a probable causality between certain gut microbiota and AA, thus providing vital insights into its pathogenesis and potential preventative and therapeutic approaches.