Ulcerative colitis and Crohn’s disease are the two main forms of inflammatory bowel disease (IBD). Here, we report the first trans-ethnic association study of IBD, with genome-wide or Immunochip genotype data from an extended cohort of 86,640 European individuals and Immunochip data from 9,846 individuals of East-Asian, Indian or Iranian descent. We implicate 38 loci in IBD risk for the first time. For the majority of IBD risk loci, the direction and magnitude of effect is consistent in European and non-European cohorts. Nevertheless, we observe genetic heterogeneity between divergent populations at several established risk loci driven by a combination of differences in allele frequencies (NOD2), effect sizes (TNFSF15, ATG16L1) or a combination of both (IL23R, IRGM). Our results provide biological insights into the pathogenesis of IBD, and demonstrate the utility of trans-ethnic association studies for mapping complex disease loci and understanding genetic architecture across diverse populations.

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory disorder with an unknown etiology. IBD is composed of two different disease entities: Crohn's disease (CD) and ulcerative colitis (UC). IBD has been thought to be idiopathic but has two main attributable causes that include genetic and environmental factors. The gastrointestinal tract in which this disease occurs is central to the immune system, and the innate and the adaptive immune systems are balanced in complex interactions with intestinal microbes under homeostatic conditions. However, in IBD, this homeostasis is disrupted and uncontrolled intestinal inflammation is perpetuated. Recently, the pathogenesis of IBD has become better understood owing to advances in genetic and immunologic technology. Moreover, new therapeutic strategies are now being implemented that accurately target the pathogenesis of IBD. Beyond conventional immunesuppressive therapy, the development of biological agents that target specific disease mechanisms has resulted in more frequent and deeper remission in IBD patients, with mucosal healing as a treatment goal of therapy. Future novel biologics should overcome the limitations of current therapies and ensure that individual patients can be treated with optimal drugs that are safe and precisely target IBD.

Metformin use has been associated with decreased cancer risk and mortality. However, the effects of metformin on clinical outcomes of colorectal cancer (CRC) are not defined. This study aimed to evaluate the association between metformin use and mortality of CRC in diabetic patients. We identified 595 patients who were diagnosed both CRC and diabetes mellitus. Patients were compared by two groups; 258 diabetic patients taking metformin and 337 diabetic patients not taking metformin. Patient's demographics, clinical characteristics, overall mortality and CRC-specific mortality were analyzed. After a median follow-up of 41 months, there were 71 total deaths (27.5%) and 55 CRC-specific deaths (21.3%) among 258 patients who used metformin, compared with 136 total deaths (40.4%) and 104 CRC-specific deaths (30.9%) among 337 patients who did not use metformin. Metformin use was associated with decreased overall mortality (p 5 0.018) and CRC-specific mortality (p 5 0.042) by univariate analysis. After adjustment for clinically relevant factors, metformin use showed lower risk of overall mortality (HR, 0.66; 95% CI 0.47620.923; p 5 0.015) and CRC-specific mortality (HR, 0.66; 95% CI 0.4520.975; p 5 0.037) in CRC patients with diabetes. Metformin use in CRC patients with diabetes is associated with lower risk of CRC-specific and overall mortality.Colorectal cancer (CRC) is the third leading cause of cancerrelated death.

Metagenomic studies show that diverse resident viruses inhabit the healthy gut; however, little is known about the role of these viruses in the maintenance of gut homeostasis. We found that mice treated with antiviral cocktail displayed more severe dextran sulfate sodium (DSS)-induced colitis compared with untreated mice. DSS-induced colitis was associated with altered enteric viral abundance and composition. When wild-type mice were reconstituted with Toll-like receptor 3 (TLR3) or TLR7 agonists or inactivated rotavirus, colitis symptoms were significantly ameliorated. Mice deficient in both TLR3 and TLR7 were more susceptible to DSS-induced experimental colitis. In humans, combined TLR3 and TLR7 genetic variations significantly influenced the severity of ulcerative colitis. Plasmacytoid dendritic cells isolated from inflamed mouse colon produced interferon-β in a TLR3 and TLR7-dependent manner. These results imply that recognition of resident viruses by TLR3 and TLR7 is required for protective immunity during gut inflammation.

This is the largest case series to document the clinical features and changes in diagnostic modalities, medical and surgical managements, and their outcomes in SMAS patients. Laparoscopic duodenojejunostomy is the preferred surgical procedure when medical management of the disease fails.

Our study provides new biological insight to CD and supports the complementary value of genetic studies in different populations.

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