Mo1870 Measuring Anti-Vinculin and Anti-CdtB Antibodies in Two Animal Models of Post-Infectious IBS

Abstract

Diverticulosis is a common GI condition among older adults in the United States. However, limited information exists on the etiologic risk factors for diverticulosis. We hypothesized that the gut microbiome and chronic inflammation contribute to the development of diverticulosis.We evaluated the association between gut bacteria, mucosal inflammation and diverticulosis in a case-control study. Methods:Participants (n=196) were consented patients who underwent screening colonoscopy at UNC Hospitals. Subjects were classified as case if diverticula were present or control if no diverticula were present. The abundance of specific bacteria in the sigmoid mucosa was determined by qPCR based on the bacterial 16s rRNA gene for Bacteroides, Bifidobacterium, Clostridium, E. coli, Lactobacillus, and Eubacteria.Mucosal mRNA gene expression of cytokines of IL-6, IL-10, IL-17, and TNF-α and housekeeping gene HMBS were assessed by qRT-PCR. Immune cells in the lamina propria were stained for CD4, CD8, CD57 and Mast cell tryptase (MCT) by immunohistochemistry (IHC). The IHC stained sections were digitally imaged using the Aperio ScanScope XT. Analysis of biomarkers was performed using Definiens Tissue Studio software with the Composer_ Nuclei_and_Simulated_Cells algorithm. The percent cells with strong (+3), medium (+2) and weak (+1) positive signal, was used to compare biomarker levels among tissue samples. Statistical analysis included t-test and logistic regression to compare cases and controls as well as Spearman correlation to assess association between bacteria and inflammation. Results:We observed a higher relative abundance of Clostridium, Bacteroides, Bifidobacterium, E. coli, and Eubacteria in cases compared to controls. Cases had lower density of CD8 compared to controls. Although the cytokine gene expression levels of IL-6, IL-10, IL-17, and TNF-α did not differ between cases and controls, there was a significant positive correlation between CD57 expression and IL-6 (r=0.23, p=0.03), CD57 and TNFα (r0.33, p=0.001) and CD57 and IL-10 (r=0.22, p= 0.03) among cases. The association between bacterial abundance and immune cell density also varied depending on case-control status. Among cases, MCT expression showed positive correlations with Bacteroides (r=0.21, p= 0.05), Clostridium (r=0.18, p=0.08) and inverse correlation with Bifidobacteria (r=-0.26, p= 0.01). Among controls, CD57 expression was inversely correlated with Lactobacillus (r=0.19, p=0.06). Conclusions: Our findings suggest that gut bacteria and inflammation are associated with diverticulosis. This data combined with further research could have clinical implications for the prevention and treatment of diverticulosis.