Immunohistochemical evaluation of galectin-2, galectin-3, and galectin-4 expression in the gastrointestinal tract of dogs with and without immunosuppressant-responsive enteropathy

Galectins play an important role in intestinal immune modulation. Little is known about galectin expression in the normal gastrointestinal tract (GIT) of dogs or their potential role in canine immunosuppressant-responsive (IR) chronic inflammatory enteropathy (CIE). In this study, we described and compared the expression of galectins in the stomach, duodenum, ileum, and colon of dogs without CIE-IR (healthy dogs) ( n = 5) and dogs with CIE-IR ( n = 7). Cellular localization of galectins was evaluated using immunohistochemistry quantified with open-source digital pathology software (QuPath). Immunoreactivity in the normal GIT was intense for Gal-2, weak for Gal-3, and moderate for Gal-4. Gal-2 was expressed throughout the gastric mucosa, including epithelium, pits, glands, and lamina propria, whereas Gal-3 and Gal-4 were expressed in the lower two-thirds of the mucosa. In healthy dogs, inflammatory cells, myenteric plexus neurons, and smooth muscle cells were immunoreactive for the examined galectins, whereas enteroendocrine and goblet cells were only immunoreactive for Gal-4. Quantitatively, Gal-2 expression was significantly higher than Gal-3 and Gal-4 in the stomach and duodenum ( P < .05) and higher than Gal-3 in the ileum. In the colon, Gal-2 and Gal-4 expressions were significantly ( P < .05) higher than Gal-3. The expressions of Gal-2, Gal-3, and Gal-4 in duodenum, ileum, and colon of dogs with CIE-IR were significantly ( P < .05) lower than in healthy dogs. A potential role for Gal-2, Gal-3, and Gal-4 in GIT immune regulation and their involvement in the pathogenesis of CIE-IR in dogs is possible and warrants further study.