Causal Links between Immune Cells and Asthma: Insights from a Mendelian Randomization Analysis

Recent studies suggest immunophenotypes may play a role in asthma, but their causal relationship has not been thoroughly examined. We used single nucleotide polymorphism (SNP)-derived instrumental variables. Summary data from 731 immune cell profiles and asthma cases were analyzed from genome-wide association studies (GWAS) of European populations. Mendelian Randomization (MR) analyses included inverse variance weighted (IVW), weighted median, and MR–Egger methods. Pleiotropy was assessed using the MR-Egger intercept and MR pleiotropy residual sum and outlier (MR-PRESSO) tests. Reverse MR analysis explored bidirectional causation between asthma and immunophenotypes. All statistical analyses were conducted using R software. MR analysis identified 108 immune signatures potentially contributing to asthma. Two immunophenotypes were significantly associated with asthma risk: CD4+ secreting Treg cells in allergic asthma (OR_IVW =1.078; 95% CI: 1.036–1.122; P_IVW =0.0002) and IgD + CD38- %lymphocyte cells in non-allergic asthma (OR_IVW =1.123; 95% CI: 1.057–1.194; P_IVW =0.0002). This study highlights the causal associations between specific immunophenotypes and asthma risk, providing new insights into asthma pathogenesis.