Unveiling the skin microbial guardians and assailants in psoriasis subtypes: a Mendelian randomization study

Previous studies have shown an association between skin microbiota and psoriasis, but the causal relationship between skin microbiota and different psoriasis subtypes remains unexplored. Our study employed the Mendelian randomization (MR) method, using summary statistics from Genome-Wide Association Studies, to investigate the causal relationships between skin microbiota and different subtypes of psoriasis. The inverse variance weighted (IVW) method served as the primary method in our MR study. The MR-Egger intercept test, Cochran's Q test, MR-PRESSO test, and leave-one-out analysis were conducted for sensitive analyses. Bayesian weighted Mendelian randomization (BWMR) method was conducted to enhance our results. For psoriasis vulgaris, our results showed that asv016 [Enhydrobacter (unc.)], alphaproteobacteria, and asv070 [Veillonella (unc.)] may serve as protective factors. Meanwhile, asv009 [D. nitroreducens], asv010 [Staphylococcus (unc.)], Neisseriaceae, and clostridiales were found to be risk factors. For guttate psoriasis, our findings suggested that asv023 [C. kroppenstedtii], asv039 [Acinetobacter (unc.)], bacteroidales, paracoccus, and betaproteobacteria may serve as protective factors, while asv008 [Staphylococcus (unc.)], asv061 [S. mitis], asv086 [A. johnsonii], finegoldia, and flavobacteriaceae emerged as potential risk factors. For generalized pustular psoriasis, our findings identified asv039 [Acinetobacter (unc.)], asv009 [D. nitroreducens], and Staphylococcus as potential protective factors, whereas asv016 [Enhydrobacter (unc.)], asv006 [S. hominis], bacteroidales, and bacteroides emerged as potential risk factors. For psoriatic arthropathies, our findings suggested that Propionibacterium, asv053 [Streptococcus (unc.)], asv093 [Staphylococcus (unc.)], rothia may serve as protective factors, while asv012 [S. hominis], corynebacterium, clostridiales, flavobacteriaceae, anaerococcus, asv013 [S. epidermidis] were associated with increased risk. Our findings suggest potential causal relationships between certain skin microbiota and different subtypes of psoriasis, highlighting their potential as novel biomarkers for diagnosing different subtypes of psoriasis, and offering promising avenues for developing microbiome-based diagnostics and targeted therapies for diverse psoriasis subtypes.