Genetically proxied IL-6 receptor inhibition is associated with increased risk of atopic dermatitis

Abstract

BackgroundDermatitis has been reported after initiation of IL-6 receptor inhibitors (IL-6Ri), while genetic association studies of atopic dermatitis (AD) have implicated IL-6R pathway signalling. However, causality remains unclear. As indications for IL-6Ri expand, so do the clinical importance of determining whether there is mechanistic evidence linking it to AD. ObjectiveTo examine the association between IL-6Ri and risk of AD. MethodsTo genetically mimic IL-6Ri, we selected single nucleotide polymorphisms within or near the IL6R gene associated with C-reactive protein (CRP) at genome-wide significance among 343,524 individuals. Genetic data for AD were obtained from 10,788 cases and 30,047 controls of European ancestry. We used the inverse-variance weighted and pleiotropy-robust methods and examined genetic confounding using colocalization. Analyses were replicated using 13,473 AD Finnish cases and 2,385 East Asian cases. Results from three independent analyses were pooled by meta-analysis. ResultsGenetically proxied IL-6Ri was associated with increased risk of AD (OR 1.78 per 4.4 mg/l reduction in CRP; 95%CI 1.28, 2.48; p=6.5x10-4). Results were replicated using Finnish outcome data (OR 2.07; 95%CI 1.58, 2.72; p=1.57x10-7), and Eastern Asian datasets (OR 1.68; 95%CI 1.12, 2.54; p=0.013). Meta-analysis of three independent populations (OR 1.89; 95%CI 1.57, 2.28; p=2.68x10-11) showed no statistical evidence of heterogeneity (p=0.65). We found no statistical evidence for pleiotropy or genetic confounding. ConclusionThis genetic investigation provides consistent evidence, across independent multi-ancestry populations, that IL-6R signalling is causally implicated in AD susceptibility. Clinicians should remain vigilant for adverse effects resembling AD when using IL-6R inhibitors for immune-mediated inflammatory diseases.