Neuromedin B identified as a therapeutic target for atopic dermatitis: evidence from Mendelian randomization and PCR validation.

Introduction: Atopic dermatitis (AD) is a long-standing inflammatory dermatosis marked by intense itching and immune imbalance. Despite recent advances in targeted biologic therapies, limitations in efficacy and cost highlight the urgent need for novel therapeutic targets. Methods: We employed Mendelian randomization (MR) by combining genome-wide association studies (GWAS), expression quantitative trait loci (eQTL), and protein QTL (pQTL) datasets to identify causal druggable genes associated with AD. To enhance the validity of causal inference, we further utilized colocalization and summary-data-based MR (SMR) techniques. We validated the expression of five prioritized genes using reverse transcription quantitative PCR (RT-qPCR), performed on RNA extracted from the peripheral blood of AD patients and healthy controls. Results: The MR approach revealed 32 candidate genes with potential druggable properties linked to AD, with 12 showing strong colocalization signals (posterior probability of hypothesis 4 (PP.H4) > 0.8). The pQTL analysis indicated that increased plasma NMB levels were associated with a heightened risk of AD (OR = 1.18, Conclusion: Integrative MR and PCR validation across Icelandic, Finnish and Chinese samples nominates NMB as a candidate AD target. These preliminary, multi-ancestry signals now require replication in large, population-matched cohorts before any therapeutic translation.