Decoding the skin microbiota: A Mendelian randomization study reveals new insights into acne causality

The link between skin microbiota and acne, despite being a research focus for years, still lacks full understanding and remains controversial. The genome-wide association studies data utilized in this study were all sourced from public databases. Microbiota data from sebaceous (acne-prone) skin regions were selected for bidirectional Mendelian randomization analysis with acne. The primary method utilized was the inverse-variance weighted (IVW) method, supported by heterogeneity analysis, horizontal pleiotropy testing, outlier detection, and "leave-one-out" sensitivity analysis. This Mendelian randomization analysis revealed causal connections between the abundance of the genus: staphylococcus (IVW odds ratio [OR]: 1.074; 95% confidence interval [CI]: 1.031-1.119, P = .001) and Propionibacterium acnes (IVW OR = 1.039, 95% CI = 1.007-1.073, P = .017) in sebaceous skin and the risk of acne development. Additionally, ASV004 (Corynebacterium [unclassified]) (IVW OR = 0.967, 95% CI = 0.937-0.999, P = .044) and ASV008 (Staphylococcus [unclassified]) (IVW OR = 0.943, 95% CI = 0.897-0.991, P = .021) were identified as protective factors that could reduce acne incidence. No reverse causality between skin microbiota and acne was found, with all analyses showing no horizontal pleiotropy or heterogeneity. This study is instrumental in exploring the link between skin microbiota and acne, supporting theoretical debates, and shedding light on acne's pathogenesis.