The Polymorphisms of Interleukin-12B Gene and Susceptibility to Inflammatory Bowel Diseases: A Meta-analysis and Trial Sequential Analysis

Objective: Inflammatory bowel disease (IBD) is a heterogeneous complex disease referring to two chronic disorders: Crohn’s disease (CD) and ulcerative colitis (UC). To clarify the relationship between IL-12B gene polymorphisms and susceptibility to CD and UC, a meta-analysis was conducted.Methods: A comprehensive search of the PubMed, Web of Science, Embase and Cochrane databases was conducted up to Oct 2019. Studies evaluating the relationship between risk of IBD and variants of IL-12B (rs6887695, rs3212227 and rs10045431) were included. Odds ratio (OR) and 95% confidence interval (CI) were calculated. Trial sequential analysis (TSA) was implemented to estimate the required information size (RIS) and evaluate the credibility of the meta-analysis results.Results: Seventeen studies containing 9827 patients with CD, 7583 patients with UC and 16044 controls were included. The results showed significant association between rs6887695 polymorphism and susceptibility to CD (allele model: OR = 1.17, 95% CI: 1.12–1.22) and UC (allele model: OR = 1.16, 95% CI: 1.09–1.23), and “C” allele carriers had a higher risk, with TSA conclusive. For rs10045431, no significant association with CD susceptibility was identified, while a significantly increased risk in UC was found (allele mode: OR = 1.16, 95% CI: 1.07–1.25), both results were conclusive according to TSA. No significant association between rs3212227 and CD or UC susceptibility was found, and TSA research warranted further investigation to certify the results. No significant heterogeneity was found.Conclusion: IL-12B rs6887695 polymorphism was associated with increased risk of CD and UC, while IL-12B rs10045431 polymorphism might only be correlated with the risk of UC.Abbreviations: IBD: inflammatory bowel disease; CD: Crohn’s disease; UC: ulcerative colitis; IL-12B: interleukin-12B; OR: odds ratio; CI: confidence interval; TSA: trial sequential analysis; RIS: required information size; DCs: dendritic cells; NK: nature killer; APCs: antigen-presenting cells; TNF: tumor necrosis factor; SNP: single nucleotide polymorphisms; HWE: Hardy–Weinberg equilibrium; NOS: Newcastle–Ottawa scale; RRR: relative risk reduction