Objective  To investigate the causal relationship between inflammatory factors and inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), using Mendelian randomization (MR).

Methods  Inflammatory factors data were obtained from the University of Bristol database and the GWAS Catalog database, and IBD data were obtained from the FinnGen database. Inverse-variance weighted was used as the primary analysis method, supplemented by weighted median estimator, weighted mode, and MR-Egger analysis methods. Sensitivity analyses such as heterogeneity and pleiotropy further validated the robustness of the results, multivariate Mendelian randomization (MVMR) analysis was performed to enhance the reliability of the final results.

Results  Forward MR analysis found that a total of 24 inflammatory factors were causally associated with IBD, while reverse MR analysis did not find a causal relationship between the two. MVMR analysis showed that AXIN1 and CD6 were positively correlated with IBD; IL10, CXCL5, and TRANCE were negatively correlated with UC, while IL-1α was positively correlated with UC; b-FGF, AXIN1, CD6, and IL-10Rα were positively correlated with CD, while TGF-β1 was negatively correlated with CD.

Conclusion  Some inflammatory factors have a causal relationship with IBD and may play a role in its pathogenesis.

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