Causal effects between inflammatory bowel disease and oral diseases based on Oral-GUT Axis: a Mendelian randomization study

Abstract

Abstract Objective Several previous studies have suggested oral diseases was correlated to Inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), but the causality and direction of action remained largely unclear. Therefore, this study will through a bidirectional two-sample Mendelian randomization (MR) based on the oral-gut axis to explore evidence for oral diseases with IBD and its two main subtypes. Methods We sourced summary statistics from the GWAS database on four oral diseases with each of the three IBD databases for exposure-outcome by bidirectional MR. The MR analyses were performed using IVW as the main effect estimate measure and a series of sensitivity analyses and potential heterogeneity tests were applied to make the results more reliable. And then, we chose either a random-effects model or a fixed-effects model for the meta-analysis based on the presence or absence of heterogeneity thereby. Results From oral diseases to IBD, we found a significant effect of genetically predict lichen planus on IBD [OR: 1.069; 95%CI: 1.043–1.097; P < 0.01], CD [OR: 1.090; 95%CI: 1.056–1.125; P < 0.01] and UC [OR: 1.075; 95%CI: 1.040–1.111; P < 0.01]. From IBD to oral diseases, we found a positive effect of whole IBD on periodontal disease [OR: 1.051; 95%CI: 1.020–1.083; P < 0.01], lichen planus [OR: 1.166; 95%CI: 1.011–1.344; P = 0.04] and oral ulcer [OR: 1.003; 95%CI: 1.001–1.004; P < 0.01]. In subtype analysis, we found a suggestive association between UC and periodontal disease [OR: 1.043; 95%CI: 1.009–1.077; P = 0.01], as well as a significant effect of CD on lichen planus [OR: 1.088; 95%CI: 1.038–1.141; P < 0.01]. Conclusion Our study provides modest evidence for a causal effect between oral diseases and IBD, which can help guide clinical treatment and decision-making for the oral health of patients with IBD, and also somewhat supports the clinical need to predict the extent of IBD disease activity in patients with oral problems.