Dynamic distribution of Paneth cells in pig intestine under normal and infection conditions

Paneth cells, a type of intestinal epithelial cell, are primarily located at the base of the intestinal crypts and adjacent to intestinal stem cells. They play a crucial role in maintaining the intestinal mucosal barrier by regulating the gut microbiota and supporting intestinal stem cells. Although some studies reported the morphology and distribution of Paneth cells in humans and mice, controversy persists regarding their distribution in farm animals, particularly in the small intestine of pigs. This study optimized the immunohistochemical staining method for Paneth cells by testing different fixatives and using lysozyme and Sox9 as markers to identify Paneth cells in the pig small intestine. The study found that Paneth cells are mainly distributed in the duodenal segment of the pig small intestine, and their population increases as piglets grow. Paneth cells are more widely distributed in black pigs, which have strong disease resistance. The number of Paneth cells is dramatically reduced after enterovirus infection. Furthermore, pretreatment with Bacillus subtilis effectively rescues the reduction in Paneth cell number caused by porcine epidemic diarrhea virus infection in piglets. L-arginine treatment can rescue the reduced Paneth cell population caused by PDCoV infection. This study comprehensively analyzed the distribution and function of Paneth cells in the pig small intestine, providing a new theoretical basis for improving the intestinal mucosal barrier and enhancing immune defense.