The IBD-candidate gene, PTPN2, Regulates Goblet Cell Number and Expression of Intestinal Epithelial Cell Markers in a Regional-specific Manner in Mice

Abstract

Loss-of-function variants in the Protein Tyrosine Phosphatase non-receptor Type 2 ( PTPN2) gene are associated with increased risk of Inflammatory Bowel Disease (IBD). PTPN2 encodes T Cell Protein Tyrosine Phosphatase (TCPTP), a negative regulator of intracellular signaling pathways including JAK-STAT. PTPN2 is critical for intestinal epithelial cell (IEC) barrier maintenance, IEC-macrophage crosstalk, and modulating the gut microbiota in mice and IBD patients. Aim: To determine if Ptpn2 loss compromises IEC subtypes that restrict gut dysbiosis. Methods: Ileal and colonic IEC subtypes and their function were assessed by PAS staining of goblet cells and immunostaining. RNA isolated from colonic IECs of whole-body Ptpn2-wild-type (WT), heterozygous (Het) and KO mice was assayed by two separate Nanostring ® panels: PanCancer and AutoImmune totaling >1500 targets. Flow cytometry was performed to evaluate abundance of mucosal-associated immune cells. Results: Goblet cells were reduced in the ileal and cecal crypts compared with WT mice (p<0.05; n=5) while numbers in the proximal and distal colon were variable. Ki-67 immunostaining revealed increased proliferating cells in the proximal and distal colon (p<0.01; n=3). Nanostring analysis had 1399 targets with detectable expression. Notably, expression of growth factors Egf and Fgfr3, differentiation factors Atoh1 and Mycn, tuft cell marker Dclk1, and intestinal stem cell marker Lgr5, were all downregulated in colonic IECs from Ptpn2-KO mice compared with WT (p<0.05; FDR<0.1; n=4). Moreover, abundance of mucosal neutrophils, macrophages, CD4 + expressing IFN-γ, CD8 + expressing TNF/IFN-γ, and CD4 + expressing IL-22 T-cells were higher in colon and cecum of Ptpn2-KO mice compared with WT and HET mice (p<0.01; n=5), whereas abundance of IL-4 expressing CD4 + cells, and Tregs expressing IL-10 were decreased in all intestinal segments of Ptpn2-KO mice (p<0.01; n=5). Conclusion: Ptpn2 loss negatively impacts abundance of IEC subtypes in a region-specific manner, affecting epithelial proliferation and expression of critical differentiation/cell markers. The elevated abundance of immune cells expressing pro-inflammatory signals accompanied by decreased levels of cells expressing IL-4 and IL-10, could contribute to a skewed abundance of IEC subtypes and their function. The observed effects may contribute to the increased susceptibility to infection and the dysbiotic microbiota in Ptpn2-deficient mice, and partly explain association of PTPN2 variants with dysbiosis in clinical IBD. Supported by NIH 2R01DK091281, 1R01AI153314-01, R21AI152017 and R01AI165490 (DFM). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.