Mendelian randomization study of inflammatory bowel disease and type 1 diabetes.

PURPOSE: Our purpose was to investigate and test the causal relationship between type 1 diabetes (T1D) and inflammatory bowel disease (IBD) and its major phenotypes, including ulcerative colitis (UC) and Crohn's disease (CD), in two large datasets. METHODS: We obtained IBD samples from the largest publicly available genome-wide association study (GWAS), as well as the FinnGen database and the publicly accessible IEU GWAS database of T1D. We employed a two-sample Mendelian randomization approach to assess bidirectional causality using the inverse variance weighting (IVW) method as the primary outcome. RESULTS: Genetic predisposition to T1D was associated with reduced risk of IBD (IVW: odds ratio (OR), 0.867; 95% confidence interval (CI), [0.852, 0.883]; P < 0.001), UC (OR = 0.879 [0.823, 0.939], P < 0.001), and CD (OR = 0.925 [0.872, 0.981], P = 0.009). The republication results found IBD genetically possessed negative association with T1D (OR = 0.781 [0.684, 0.891], P < 0.001). Additionally, a meta-analysis of results was conducted to prove the strong evidence between T1D and CD (OR = 0.95 [0.91, 0.98]; p = 0.01). CONCLUSIONS: This study first demonstrated a causal effect of TID on the reduced risk of CD in the mendelian randomization study.

Identification of novel factors that affect the onset of idiopathic chronic pancreatitis: The role for microRNA-323b-5p.

BACKGROUND: The c.194+2 T>C variant of serine protease inhibitor Kazal type 1 (SPINK1) is a known genetic risk factor found in Chinese patients with idiopathic chronic pancreatitis (ICP), but the early-onset mechanisms of ICP are still unclear. METHODS: Complementary experimental approaches were used to pursue other potential pathologies in the present study. The serum level of SPINK1 of ICP patients in the Han population in China was detected and verified by an enzyme-linked immunosorbent assay. Next, differentially expressed proteins and microRNAs from plasma samples of early-onset and late-onset ICP patients were screened by proteomic analysis and microarray, respectively. RESULTS: Combined with these advanced methods, the data strongly suggest that the regulatory effects of microRNAs were involved in the early-onset mechanism of the ICP by in vitro experiments. There was no significant difference in the plasma SPINK1 expression between the early-onset ICP and the late-onset patients. However, the expression of plasma glutathione peroxidase (GPx3) in early-onset ICP patients was markedly lower than that in late-onset ICP patients, although the level of hsa-miR-323b-5p was lower in late-onset patients compared to the early-onset ICP group. In vitro experiments confirmed that hsa-miR-323b-5p could increase apoptosis in caerulein-treated pancreatic acinar cells and inhibit the expression of GPx3. CONCLUSIONS: The up-regulated hsa-miR-323b-5p might play a crucial role in the early-onset mechanisms of ICP by diminishing the antioxidant activity through the down-regulation of GPx3.