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R2745 --> Background & Aim：: Guanylate‐binding protein 5 (GBP5) is an essential component of cell‐autonomous immune responses against microbial infection. Here we investigated the potential roles for GBP5 in the pathogenesis of inflammatory bowel diseases (IBD) including Crohn's disease (CD) and ulcerative colitis (UC). Method: Colon tissues were collected from IBD patients at the Sixth Affiliated Hospital of Sun Yat‐sen University, Guangzhou, China. Colitis mice were obtained by feeding male C57BL/6 mice with 2.5% dextran sulfate sodium (DSS) water for 7days. Global gene expression profiles in the colonic mucosa of CD and UC were examined with our microarray dataset GSE16879. Individual gene and protein expression were analyzed by quantitative real‐time PCR (qPCR) and Western blot, respectively. Gene enrichment analysis was performed with WEB‐based Gene Set Analysis Toolkit (WebGestalt). Immunohistochemistry and three‐color immunofluorescence were performed to examine the tissue and cellular localization of GBP5. Three GBP5 specific siRNA were used to transfect THP‐1 and Jurkart T cells to investigate the cellular function of GBP5. Result: Both immunohistochemistry and immunofluorescence analyses indicated that GBP5 was only expressed in immune cells including T lymphocytes, B lymphocytes and macrophages, in the mucosa and the germinal center of the intestine, More GPB5 positive cells were observed in areas with more severe inflammation from the same patient. Consistently, highly elevated GBP5 expression was observed in the colonic mucosa of IBD patients and DSS induced colitis mice, In addition, the expression level of GBP5 returned to normal levels in the responders after infliximab treatment, but remained elevated in the non‐responders (Figure 1). From our transcriptome dataset, genes correlated with GBP5 were identified, and these genes were enriched in myeloid leukocyte activation and immune effector process, In line with this, GBP5 knockdown with siRNA in THP‐1 and Jukart T cell line led to the decreased expressions of TNFα, IFNG, IL‐8, IL‐18, CASP2, NLRP1 and NLRP4 (Figure 2). Discussion: Our observations demonstrated that GBP5 participated in IBD pathogenesis, The role of GBP5 in IBD may involve the regulation of immune cells and cytokines, Since GBP5 is a microbial sensor, our study may supply a novel link between the host and gut microbiota in the pathogenesis of IBD. Future effort will use the intestinal gbp5‐/‐ conditional knockout mouse model to define the exact role of GBP5 in IBD. [ABSTRACT FROM AUTHOR]

R4363 --> 826.6 --> Background: Previous studies reported inconsistent results regarding altered gut microbiome in patients with Crohn's disease (CD), likely due to the large impact of genetic polymorphisms and environmental factors on the structure of the gut microbiota. We aim to investigate the altered microbiome in CD with a cohort that minimizes the impact of irrelevant genetic and environmental factors on the gut microbiota. Method: Stool samples and clinical records were collected from 91 patients withCD and their healthy siblings in the Sixth Affiliated Hospital of Sun Yat‐sen University in Guangzhou, China, between March 2014 and December 2018. Fecal DNA was isolated and the V5‐V6 region of the 16S rRNA gene was sequenced on a MiSeq platform. Data was processed with QIIME2. Spearman analysis was performed to identify the microbial features correlated with inflammatory markers. Result: Compared to healthy siblings, CD patients exhibited reduced alpha diversities based on the metrics of Chao1, Shannon, and observed speciesat the ASV level (P<0.05). Beta diversity was significantly different between study groups according to UniFrac based principle coordinate analysis (P<0.001). Altered abundances were observed at various taxonomic levels comparing between CD patients and their healthy siblings, including increased abundance in Escherichia‐Shigella and Veillonella, and decreased abundance in Lachnospiraceae, Prevotella 9 and Faecalibacterium in CD patients. Spearman analysis identified significant correlations between Escherichia‐ Shigella and Lachnospiraceae with inflammatory markers erythrocyte sedimentation rate, C‐reactive protein, and white blood cell count (Fig.1). Discussion: By comparing between CD patients with their siblings, the impact of the compounding genetic and environmental factors on the gut microbita was minimized. This approach allowed the identification of CD specific microbial fearures that are correlated with inflammatory markers. Further study along this line may establish CD specific microbial targets for diagnostic and therapeutic purposes. [ABSTRACT FROM AUTHOR]

R2848 --> 826.10 --> Background: NLRP3 inflammasome is implicated in the pathogenesis of inflammatory bowel diseases (IBD). Since guanylate binding protein 5 (GBP5) induces the NLRP3 inflammasome activity, we aim to investigate the potential role of GBP5 in IBD pathogenesis. Methods: The expression of GBP5, NLRP3 inflammasome and related cytokines and chemokines were examined in two cohorts of IBD patients and healthy controls, by microarray transcriptome analysis, quantitative real time PCR, Western blot and Luminex Multi‐Analyte Profiling technology. Cellular and subcellular localization of GBP5 in colonic biopsies were examined by immunohistochemistry and immunofluorescence with confocal microscopy. For functional studies, GBP5 expression was induced by IFNγ or silenced by siRNA or CRISPR/CAS9 technique. Results: Expression of GBP5 was elevated in colonic mucosa in two geographically and culturally distinct IBD cohorts. In colonic tissues of IBD patients, the expression of GBP5 was mainly confined to immune cells and the levels of GBP5 expression were correlated with those of the inflammatory cytokines and chemokines. In cultured T and macrophage cells, expression of proinflammatory cytokines and chemokines were increased when GBP5 was induced, while GBP5 deficiency leads to decreased expression of the proinflammatory mediators including gasdermin D, caspase 1 and pro‐IL1β. Conclusions: GBP5 is required in the expression of many inflammatory cytokines and chemokines in intestinal immune cells. In addition, GBP5 may up‐regulate inflammatory reactions through an inflammasome mediated mechanism. Highly elevated GBP5 expression at the inflamed colonic mucosa in two geographically and culturally distinct IBD cohorts indicates that GBP5 plays a common and important role in IBD pathogenesis, and therefore, is a potential therapeutic target for the management of IBD patients of various genetic and environmental backgrounds. [ABSTRACT FROM AUTHOR]

R2702 --> Background & Aims: FUT2 encodes an α‐1,2‐fucosyltransferase required for the proper production of oligosaccharides and glycoproteins. The FUT2 polymorphism has been hypothesized to mediate a genetic mechanism to impact gut microbiota and consequently contribute to IBD pathogenesis, because of the high prevalence of loss‐of‐function polymorphisms of FUT2 and their association with IBD in genome‐wide association studies. In this study, we investigated the role of the gut microbiota in IBD patients with FUT2 loss‐of‐function mutation. Method: A total of 81 inflammatory bowel disease (IBD) patients were enrolled in 6th Affiliated Hospital of Sun Yat‐sen University in Guangzhou, China between March 2016 and July 2018. To determine the genotypes of the patients at rs1047781 (A385T) and rs601338 (G428A) of the FUT2 gene, individuals were asked to provided blood samples. All participants were divided into 3 groups according to their genotypes: SeSe, Sese, and sese groups. For microbiome study, fecal DNA was collected and the V5‐V6 region of the 16S rDNA was sequenced with a MiSeq platform. Metabolomics analysis targeting SCFA was performed by gas chromatography. Result: The FUT2 genotypes are associated with specific gut microbiome compositions and functions in IBD patients. Differences in alpha‐, beta‐diversities, bacterial abundances at every taxonomic levels were observed between different FUT2 genotypes. Escherichia was significantly decreased in the gut of the sese patients. On the other hand, CD8+ inducing Alistipe and Phascolarctobacterium and Th17 inducing Erysipelotrichaceae were more abundant in sese patients suggests that these bacteria may explain the higher incidence of IBD among sese individuals. The PICRUSt functional analysis based on the 16S data showed that, several carbohydrate synthesis pathways were enriched in IBD patients with non‐functional mutation of FUT2 (P<0.05). Interestingly, SCFA‐producing bacteria in sese patient were not decreased although SCFA is protective against colon inflammation. Metabolomics analysis targeting SCFA confirmed this observation. Discussion: Data presented here explained the association of non‐secretor status with IBD. Our study supports the hypothesis that FUT2 loss‐of‐function genotype causes altered gut microbiota that is poised to the development of IBD. The identification of the T cell inducing species in this study contributes to the knowledge base for the development of personalized microbial intervention for IBD. [ABSTRACT FROM AUTHOR]