Diarrhea in humans and animals causes immense socio-economic problems. The food and feed additive zinc (Zn) has clear protective effects against diarrhea. In pigs, post weaning diarrhea (PWD), usually resulting from Enterotoxigenic E. coli (ETEC), is efficiently treated by Zn. However the use of Zn will be forbidden from 2022 on, because of environmental issues. To replace Zn efficiently as a treatment, we have to understand its function. The host lab has unraveled a new mechanism, based on a TNF model in mice. The focus lies on Paneth cells, which form the epithelial layer in the crypts in the small intestine. These cells undergo cell death by TNF, leading to permeability and inflow of bacteria in the spleen and other organs, causing septic death. The details of the impact of TNF and Zn on these cells depend on their gene expression status, which is influenced by the microbes in the gut. To understand these details, we must isolate Paneth cells via FACS, study their genome wide gene expression by RNAseq, and culture these cells to study in vitro effects of TNF and Zn. Optimizing these assays is a major challenge. Furthermore, I will establish a mouse model of PWD using ETEC bacteria and study the role of PC cell death, permeability, TNF, the heat-labile toxin of ETEC and Zn using my newly established assays. With this project, I hope to open new possibilities for the treatment of diarrhea, including PWD, an economically huge issue in an area as Flanders.