Expression of genes encoding interleukin 15 and its receptor subunits in the duodenal and colonic mucosae of dogs with chronic enteropathy.

A pro-inflammatory role of interleukin (IL)-15 and IL-15 receptor (R) in chronic intestinal inflammation, such as inflammatory bowel disease, has been reported in humans. However, the contribution of IL-15 signaling in the pathogenesis of canine chronic enteropathy (CE) remains unclear. Therefore, as a first step in elucidating the importance of IL-15 signaling in canine CE, we measured the mRNA expression of and subunits, including , and , in the duodenal and colonic mucosae of healthy dogs and those with CE, including food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE). Real-time PCR analysis revealed significantly lower mRNA expression levels in the duodenal mucosa of dogs with IRE compared to healthy dogs. In contrast, the mRNA expression levels of , and in the duodenal mucosa and , and in the colonic mucosa did not differ among healthy dogs and those with FRE, ARE, or IRE. These findings suggest that decreased mRNA expression of might be involved in the pathogenesis of duodenitis in dogs with IRE. Moreover, even in canine CE, IL-15 signaling appears to play different roles in duodenitis and colitis in dogs with FRE, ARE, and IRE. However, there were no correlations between the gene expression levels of and clinical severity or histopathological scores in the duodenum of dogs with IRE. Further studies are necessary to investigate the IL-15Rα protein localization and to determine how impaired expression contributes to the development of duodenitis in dogs with IRE.