No potential causal link between HP infection and IBD: A 2way Mendelian randomization study

Abstract

Recent epidemiological research suggests a possible negative correlation between Helicobacter pylori infection and inflammatory bowel disease (IBD). However, conflicting studies have provided unclear evidence regarding these causal relationships. Therefore, recommending specific prevention and treatment strategies for H. pylori infection and IBD is challenging. We used various antibodies (anti-H. pylori IgG, VacA, and GroEl) related to H. pylori infection as indicators. We acquired relevant genetic variants from public databases within the Genome-wide Association Studies (GWAS) dataset using IBDs tool variables from 2 different GWAS datasets. We thoroughly examined the data and screened for IVs that fulfilled these criteria. Subsequently, Bidirectional Mendelian randomization (MR) was conducted to predict the potential causality between the 2. To ensure the accuracy and robustness of our results, we conducted a series of sensitivity analyses. Based on our comprehensive MR analysis, no potential causal relationship was observed between H. pylori infection and IBD. Across various methodologies, including IVW, MR-Egger, and weighted median, our findings showed P values > .05. The only exception was observed in the reverse MR analysis using the MR-Egger method, which yielded a P value of < .05. However, because the IVW method is considered the most statistically significant method for MR, and its P value was > .05, we do not believe that a potential causal relationship exists between them. Our sensitivity analysis did not suggest significant horizontal pleiotropism. Although heterogeneity was detected in the analysis of IBD (IIBDGC source) versus H. pylori GroEL antibody levels (MR-Egger, Qp = 0.038; IVW, Qp = 0.043), the results remained reliable because we selected IVW as a random-effects model in our MR analysis method. Based on our MR research, no direct correlation was observed between H. pylori infection and IBD risk. This implies that eradicating H. pylori may not provide substantial benefits in preventing or treating regional IBD, and vice versa. Nevertheless, the use of H. pylori serological index substitution has limitations, and further research using histological diagnosis and additional MR studies is required to comprehensively assess the link between H. pylori infection and IBD.

Figure 1.

Schematic representation of the bidirectional MR study of the causal relationship between H. pylori infection and IBD. SNPs, single-nucleotide polymorphisms. H. pylori, Helicobacter pylori.

Figure 2.

Forest plot of Mendelian randomization analyses. OR, odds ratio. 95%CI, 95% confidence interval. nsnp, number of single-nucleotide polymorphisms. HP_IgG, Anti-H. pylori IgG seropositivity. HP_VacA, H. pylori VacA antibody levels. HP_GroEL, H. pylori GroEL antibody levels. IBD_Finn, GWAS data source of inflammatory bowel disease in the FinnGen database. IBD_IIBDGG, GWAS data source of inflammatory bowel disease from the International Inflammatory Bowel Disease Genetics Consortium.

Figure 3.

Scatterplot of significant causal relationships between H. pylori infection-related antibody markers and IBD. IBD (Finn), GWAS data source of inflammatory bowel disease in the FinnGen database. IBD (IIBDGG), GWAS data source of inflammatory bowel disease from the International Inflammatory Bowel Disease Genetics Consortium.

Figure 4.

Forest plot of reverse Mendelian randomization analyses. OR, odds ratio. 95%CI, 95% confidence interval. HP_IgG, Anti-H. pylori IgG seropositivity. HP_VacA, H. pylori VacA antibody levels. HP_GroEL, H. pylori GroEL antibody levels. IBD_Finn, GWAS data source of inflammatory bowel disease in the FinnGen database. IBD_IIBDGG, GWAS data source of inflammatory bowel disease from the International Inflammatory Bowel Disease Genetics Consortium.