Objective To explore the causal association between immune cells and allergic rhi-nitis using Mendelian randomization(MR)approach.Methods GWAS data for 731 types of im-mune cells and allergic rhinitis were obtained from genome-wide association study(GWAS)databas-es.A two-sample bidirectional MR analysis was conducted,with the inverse-variance weighted(IVW)method as the primary analytical approach,and the weighted median method,MR-Egger re-gression,simple mode method,and weighted mode method as supplementary approaches.Sensitivity analyses,including heterogeneity tests,pleiotropy tests,and the leave-one-out method,were per-formed.Bonferroni correction was applied to the preliminary results to enhance their reliability and rigor.Results The two-sample forward MR analysis revealed correlations between 67 immune cell phenotypes and allergic rhinitis.After Bonferroni correction,four immune cell phenotypes were finally identified.Among them,the expression of CD3 on CD39-positive activated CD4 regulatory T cells(OR=0.953,95％CI,0.931 to 0.978,P＜0.001,Padj=0.007),the expression of herpesvirus entry mediator(HVEM)on CD45RA-negative CD4+T cells(OR=0.965,95％CI,0.948 to 0.983,P＜0.001,Padj=0.008),and the percentage of human leukocyte antigen class DR(HLA-DR)-high-expressing monocytes among leukocytes(OR=0.929,95％CI,0.885 to 0.974,P=0.002,Padj=0.157)were protective factors for allergic rhinitis.In contrast,the percentage of transitional B cells among B cells(OR=1.094,95％CI,1.032 to 1.161,P=0.003,Padj=0.183)was a risk factor for allergic rhinitis.The reverse MR analysis showed no causal relationship between allergic rhinitis and the four immune cell phenotypes.Conclusion The two-sample forward MR analysis confirms a caus-al link between immune cells and allergic rhinitis.MR analysis has the advantages of reducing con-founding factor interference and avoiding reverse causation,providing a theoretical basis for in-depth research on immune mechanisms,sensitive biomarkers,and drug treatment targets of allergic rhinitis.

Objective To investigate the causal association between bronchial asthma and bone mineral density at different sites using a two-sample Mendelian randomization (MR) approach. Methods Summary data for exposure factors and outcome were obtained from different genome-wide association studies.Single nucleotide polymorphisms strongly associated with bronchial asthma were selected as instrumental variables,and those in linkage disequilibrium were excluded.The inverse-variance weighted (IVW) method was used as the primary method for MR analysis,complemented by weighted median,simple mode,weighted mode,and MR-Egger regression methods.Sensitivity analyses were conducted to assess the stability of the results. Results The random-effects model of IVW analysis showed that heel bone mineral density (OR=0.986;95% CI,0.974 to 0.998;P=0.023) as the outcome dataset had a reverse causal effect with bronchial asthma,while lumbar spine bone mineral density (OR=1.031;95% CI,0.984 to 1.081;P=0.195),femoral neck bone mineral density (OR=1.014;95% CI,0.973 to 1.057;P=0.505),and forearm bone mineral density (OR=1.011;95% CI,0.935 to 1.094;P=0.775) as outcome datasets showed no causal effect with bronchial asthma.The MR-Egger intercept test results indicated that the P-values for the intercepts of lumbar bone mineral density,femoral neck bone mineral density,forearm bone mineral density,and calcaneal bone mineral density were all over 0.05,suggesting no horizontal pleiotropy and relatively stable results. Conclusion MR analysis reveals a reverse causal effect between bronchial asthma and heel bone mineral density,suggesting that clinicians should strengthen the monitoring of heel bone mineral density in patients with bronchial asthma to timely detect and intervene osteoporosis.