Unraveling the causal link between immune cells and temporomandibular disorders: A Mendelian randomization analysis

The host's immune inflammatory response plays a crucial role in the pathogenesis of temporomandibular disorders (TMD), involving numerous innate immune effector cells to initiate the initial inflammatory response. However, the regulation of immune function and the composition of immune cells in relation to the occurrence and development of TMD remain incompletely elucidated. The genetic causality of immune cells on TMD was studied using Mendelian randomization in a two-sample study. With the help of publicly available genetic data, we examined the causal associations between 731 immune cell signatures and TMD risk. For the causal effect analysis, an inverse variance-weighted random effect model was applied. Several sensitivity analyses were conducted by using Cochran's Q tests, funnel plots, leave-one-out analyses, and Mendelian randomization-Egger intercept tests. Twenty-nine immune cell traits might be causally related to TMD. Among these traits, 11 exhibited potential positive causal effects, while the remaining 18 displayed negative causal effects on TMD. Moreover, no substantial evidence of heterogeneity or pleiotropy was observed. We have demonstrated a close genetic connection between immune cells and TMD, unraveling the underlying mechanisms linking immune dysregulation and TMD will contribute to our understanding of the pathophysiology of this debilitating condition.