Microbial Interventions for Inflammatory Skin Diseases: A Systematic Review and Meta-Analysis of Atopic Dermatitis...

Inflammatory dermatological diseases represent a significant global health burden, with emerging evidence suggesting that modulation of the gut-skin axis microbial interventions may offer therapeutic benefits. However, current evidence is fragmented, with considerable heterogeneity limiting definitive conclusions. A systematic review and a meta-analysis were conducted following PRISMA guidelines, registered in PROSPERO (CRD42024629809). Seven databases were searched for randomized controlled trials evaluating probiotics, synbiotics, or postbiotics in inflammatory skin conditions. Primary outcomes included disease severity scores (SCORAD for atopic dermatitis, PASI for psoriasis). Statistical analysis employed random-effect models with standardized mean differences (SMDs) and Hedges' g as effect size measures, using R software. Heterogeneity among studies was assessed using Q statistics and the I² index. Results: In total, 19 studies encompassing 1104 participants met the inclusion criteria. For atopic dermatitis, a meta-analysis of 12 studies (n = 817) demonstrated significant clinical improvement with microbial interventions versus placebo (SMD = -0.72; 95% CI: -1.26 to -0.17; p = 0.015), though substantial heterogeneity in the treatment effects was observed across studies (I² = 85.1%). The psoriasis results were more variable, with five studies (n = 287) showing non-significant pooled effects (SMD = -0.63; 95% CI: -1.74 to 0.48; p = 0.192). Multi-strain formulations and synbiotic combinations appeared to show greater efficacy compared to single-strain preparations. Safety profiles remained consistently favorable across all interventions. Microbial interventions represent a promising adjunctive therapeutic approach for inflammatory dermatological diseases, particularly atopic dermatitis, acting via gut-skin axis mechanisms. The substantial heterogeneity between the included studies emphasizes the need for standardized protocols and personalized medicine approaches integrating microbiome profiling to optimize clinical outcomes.