Upregulation of signal transducer and activator of transcription 3 in dogs with chronic inflammatory enteropathies

BACKGROUND: In inflammatory bowel disease (IBD) in humans, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is upregulated in mucosal epithelial cells and correlates with clinical severity. HYPOTHESIS/OBJECTIVE: To investigate the expression pattern of pSTAT3 in the mucosa of dogs with chronic inflammatory enteropathy (CIE) and explore correlations between its expression and clinical and histopathological severity scoring. ANIMALS: Twenty‐eight canine CIE patients grouped into food‐responsive enteropathy (FRE; 9), steroid‐responsive enteropathy (SRE; 10), and protein‐losing enteropathy (PLE; 9). Ten healthy beagle dogs served as controls (CO). METHODS: Retrospective case control study. Immunohistochemistry was used to detect pSTAT3 in canine duodenal mucosa samples. RESULTS: Compared to CO, SRE (P < .001) and PLE (P < .001) dogs had significantly higher pSTAT3 expression in the villus epithelium. The SRE group had a significantly higher expression in the villus lamina propria (VLP) compared to controls (P = .009). In the crypt epithelium (CE), all CIE dogs had significantly higher pSTAT3 expression (FRE, P = .002; SRE, P = .003; PLE, P < .001) compared to CO. In the lamina propria crypt region (CLP), dogs with FRE (P = .04) and SRE (P = .03) had significantly upregulated pSTAT3 compared to controls. A positive correlation was found between canine chronic enteropathy clinical activity index (CCECAI) scoring and pSTAT3 expression for both epithelial (rho = .541; P < .001) and crypt regions (rho = .32; P = .02). CONCLUSIONS AND CLINICAL IMPORTANCE: pSTAT3 is upregulated in CIE in dogs, correlates with clinical severity, and may be helpful as a clinical marker in dogs with CIE.