The effects of Lawsonia intracellularis, Salmonella enterica serovar Typhimurium and co-infection on IL-8 and TNFα expression in IPEC-J2 cells.

Lawsonia intracellularis is among the most important enteric pathogens of swine and has been shown to be a risk factor for increased Salmonella enterica shedding. S. enterica serovar Typhimurium, in addition to being a significant pathogen of swine, also remains one of the most common causes of foodborne illness worldwide. Inflammation and the expression of IL8 and TNFα are an important process in the establishment of S. Typhimurium infection. Yet the effect of L. intracellularis on the expression of these cytokines by enterocytes, the niche both pathogens occupy during infection, is poorly understood. In this study we compared cytokine gene expression between singly and dually infected IPEC-J2 cells, a non-transformed porcine enterocyte cell line. Our results show that L. intracellularis leads to increased expression of IL8 and TNFα and has an additive effect on their expression in co-infection. The increase in expression of inflammatory cytokines may be one mechanism by which L. intracellularis favors S. Typhimurium infection.