Bidirectional Causality in IBD and Periodontitis: Insights from Mendelian Randomization and Bioinformatics

Background The causal relationship between inflammatory bowel disease (IBD) and periodontitis remains a topic of debate. This study aimed to assess the causal relationship between the two. Methods This study employed a bidirectional Mendelian randomization (MR) analysis combined with integrated bioinformatics. On one hand, it explored the causal relationship between IBD and periodontitis using bidirectional MR analysis, with inverse variance weighting (IVW) as the judgment basis and conducted sensitivity analysis. On the other hand, it utilized RNA sequencing data to mine the co-expressed differential genes between the two diseases, to explore the common inflammatory molecules and potential molecular signaling pathways between them. Results The study found a bidirectional causal link between IBD and periodontitis ( P  < 0.05), with the sensitivity analysis showing consistency and no significant heterogeneity or pleiotropy ( P  > 0.05). The results of the MR analysis further confirmed the causal relationship between them. The integrated bioinformatics analysis indicated that immune-related factors, represented by IL1B and CXCR4, and signaling pathways, notably TNF and IL17, may play an important role in the progression of both diseases. Conclusion This study, through Mendelian Randomization analysis, established a mutual causal relationship between IBD and periodontitis. The transcriptome sequencing data analysis revealed the common pathological mechanisms and the role of key immune regulatory factors in these diseases. These findings provide important scientific basis for the diagnosis and treatment of IBD and periodontitis, emphasizing the importance of a deep understanding of the interaction between these diseases.