Genotype-Phenotype Associations of the CD-Associated Single Nucleotide Polymorphism within the Gene Locus Encoding Protein Tyrosine Phosphatase Non-Receptor Type 22 in Patients of the Swiss IBD Cohort.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) plays an important role in immune cell function and intestinal homeostasis. The single nucleotide polymorphism (SNP) rs2476601 within the PTPN22 gene locus results in aberrant function of PTPN22 protein and protects from Crohn's disease (CD). Here, we investigated associations of PTPN22 SNP rs2476601 in inflammatory bowel disease (IBD) patients in the Swiss IBD Cohort Study (SIBDCS). 2'028 SIBDCS patients (1173 CD and 855 ulcerative colitis (UC) patients) were included. The clinical characteristics were analysed for an association with the presence of the PTPN22 SNP rs2476601 genotypes 'homozygous variant' (AA), 'heterozygous' (GA) and 'homozygous wild-type' (GG). 13 patients (0.6%) were homozygous variant (AA) for the PTPN22 polymorphism, 269 (13.3%) heterozygous variant (GA) and 1'746 (86.1%) homozygous wild-type (GG). In CD, AA and GA genotypes were associated with less use of steroids and antibiotics, and reduced prevalence of vitamin D and calcium deficiency. In UC the AA and GA genotype was associated with increased use of azathioprine and anti-TNF antibodies, but significantly less patients with the PTPN22 variant featured malabsorption syndrome (p = 0.026). Our study for the first time addressed how presence of SNP rs2476601 within the PTPN22 gene affects clinical characteristics in IBD-patients. Several factors that correlate with more severe disease were found to be less common in CD patients carrying the A-allele, pointing towards a protective role for this variant in affected CD patients. In UC patients however, we found the opposite trend, suggesting a disease-promoting effect of the A-allele

Contribution of CD3(+)CD8(-) and CD3(+)CD8(+) T Cells to TNF-alpha Overexpression in Crohn Disease-Associated Perianal Fistulas and Induction of Epithelial-Mesenchymal Transition in HT-29 Cells

Background Fistulas represent a frequent and severe complication in patients with Crohn disease (CD). Tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta, and interleukin (IL)-13 are known to trigger epithelial-mesenchymal transition (EMT), promoting fistula formation. Here, we investigated the role of T-lymphocytes (T cells) in fistula pathogenesis. Methods CD3(+)CD8(-), CD3(+)CD8(+), or CD45(+)CD3(-) cells from healthy volunteers, patients with CD, and patients with CD with perianal fistula were co-cultured with HT-29 cells. The EMT, cytokine production, and mRNA expression were analyzed. Perianal CD fistula specimens were immunohistochemically stained for cytokines and their receptors. The effect of cytokines on EMT induction was investigated using an EMT spheroid model. Results Patients with CD with fistula revealed more CD3(+)CD8(-) and less CD3(+)CD8(+) T cells in blood than healthy control patients and patients with CD without fistula. In perianal fistula specimens, CD4(+) cells-and to a lesser extent CD8(+) cells-were highly present around fistula tracts. When co-cultured with HT-29 cells, both cell subsets promoted EMT-related gene expression and TNF-alpha production in a time-dependent manner. The CD3(+)CD8(-) T cells from patients with CD with fistula also produced higher amounts of IL-13 than cells from healthy control patients or patients with CD without a fistula. We found that IL-22 and IL-22R(alpha 1) were highly expressed in perianal CD fistula specimens and that IL-22 cotreatment potentiated TNF-alpha-induced EMT in HT-29 spheroids. Conclusions Our data indicate that both CD3(+)CD8(-) and CD3(+)CD8(+) T cells play an important role in the pathogenesis of perianal CD fistulas by the secretion of TNF-alpha. Our data support clinical evidence indicating that anti-TNF-alpha therapy is effective in fistula treatment and identify IL-13 and IL-22 as possible novel therapeutic targets for fistula therapy.Cellular mechanisms in basic and clinical gastroenterology and hepatolog

The EBI2-oxysterol axis promotes the development of intestinal lymphoid structures and colitis.

The gene encoding for Epstein-Barr virus-induced G-protein-coupled receptor 2 (EBI2) is a risk gene for inflammatory bowel disease (IBD). Together with its oxysterol ligand 7α,25-dihydroxycholesterol, EBI2 mediates migration and differentiation of immune cells. However, the role of EBI2 in the colonic immune system remains insufficiently studied. We found increased mRNA expression of EBI2 and oxysterol-synthesizing enzymes (CH25H, CYP7B1) in the inflamed colon of patients with ulcerative colitis and mice with acute or chronic dextran sulfate sodium (DSS) colitis. Accordingly, we detected elevated levels of 25-hydroxylated oxysterols, including 7α,25-dihydroxycholesterol in mice with acute colonic inflammation. Knockout of EBI2 or CH25H did not affect severity of DSS colitis; however, inflammation was decreased in male EBI2 <sup>-/-</sup> mice in the IL-10 colitis model. The colonic immune system comprises mucosal lymphoid structures, which accumulate upon chronic inflammation in IL-10-deficient mice and in chronic DSS colitis. However, EBI2 <sup>-/-</sup> mice formed significantly less colonic lymphoid structures at baseline and showed defects in inflammation-induced accumulation of lymphoid structures. In summary, we report induction of the EBI2-7α,25-dihydroxycholesterol axis in colitis and a role of EBI2 for the accumulation of lymphoid tissue during homeostasis and inflammation. These data implicate the EBI2-7α,25-dihydroxycholesterol axis in IBD pathogenesis

Supplementary Material for: The Clinical Relevance of the IBD-Associated Variation within the Risk Gene Locus Encoding Protein Tyrosine Phosphatase Non-Receptor Type 2 in Patients of the Swiss IBD Cohort

<b><i>Background/Aims:</i></b> The single nucleotide polymorphism (SNP) rs1893217 within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) results in a dysfunctional PTPN2 protein is associated with Crohn's disease (CD) and exists in perfect linkage disequilibrium with the CD- and ulcerative colitis (UC)-associated PTPN2 SNP rs2542151. We investigated associations of PTPN2 SNP rs1893217 and clinical characteristics of inflammatory bowel disease (IBD) patients. <b><i>Methods:</i></b> One thousand seventy three patients with CD and 734 patients with UC from the Swiss IBD Cohort Study (SIBDCS) were included. Epidemiologic, disease and treatment characteristics were analysed for an association with the presence of one of the rs1893217 genotypes ‘homozygous wild-type' (TT), ‘heterozygous' (CT) and ‘homozygous variant' (CC). <b><i>Results:</i></b> About 2.88% of IBD patients were identified with CC, 26.8% with CT and 70.4% with TT genotype. The CC-genotype was associated with the existence of gallstones in CD and pancolitis in UC patients. The presence of the C-allele (i.e. either CC or CT genotype) was associated with the onset of uveitis, but protected from aphthous oral ulcers in CD patients. UC patients carrying a C-allele were diagnosed at an older age but required intestinal surgery more often. The presence of the C-allele was associated with a successful treatment with anti-TNF antibodies in both CD and UC patients. <b><i>Conclusion:</i></b> IBD patients carrying the C-allele of PTPN2 SNP rs1893217 are at greater risk for developing a severe disease course but are more likely to respond to treatment with anti-TNF antibodies. These findings demonstrate a clinical relevance of this PTPN2 risk variant in IBD patients