A Co-Culture Model of IPEC-J2 and Swine PBMC to Study the Responsiveness of Intestinal Epithelial Cells: The Regulatory Effect of Arginine Deprivation

SIMPLE SUMMARY: The interest in amino acids comes from their involvement in research on alternative strategies for the utilization of antibiotics on farms. Among several substances used to replace antibiotics, there is arginine, an essential amino acid in newborns and piglets. This amino acid has a protective role in intestinal immune cells and improves intestinal immunity. The purpose of this research was to define a co-culture model, in which intestinal epithelial cells can communicate with peripheral blood mononuclear cells (PBMC) to deepen the effects of arginine deprivation on intestinal epithelial cells over time. The main finding was that the lack of arginine highly impacts on intestinal and immune cells by way of immuno-regulation mediated by the expression of pro- and anti-inflammatory cytokines. The use of this experimental model could allow us to investigate the impact of and interactions between specific nutrients and the complex intestinal environment and, in addition, to assess feed additives to improve health and animal production. ABSTRACT: Arginine is a semi-essential amino acid, supplementation with which induces a reduction of intestinal damage and an improvement of intestinal immunity in weaned piglets, but the mechanism is not yet entirely clear. The aim of this study was to characterise a co-culture model by measuring changes in gene expression over time (24 and 48 h) in intestinal IPEC-J2 cells in the presence of immune cells activated with phytohemagglutinin and, consequently, to assess the effectiveness of arginine deprivation or supplementation in modulating the expression of certain cytokines related to the regulation of intestinal cells’ function. The main results show the crucial role of arginine in the viability/proliferation of intestinal cells evaluated by an MTT assay, and in the positive regulation of the expression of pro-inflammatory (TNF-α, IL-1α, IL-6, IL-8) and anti-inflammatory (TGF-β) cytokines. This experimental model could be important for analysing and clarifying the role of nutritional conditions in intestinal immune cells’ functionality and reactivity in pigs as well as the mechanisms of the intestinal defence system. Among the potential applications of our in vitro model of interaction between IEC and the immune system there is the possibility of studying the effect of feed additives to improve animal health and production.