PNNL

Abstract

The symptoms of infectious diarrheal disease are mediated by a combination of a pathogen’s 39 virulence factors and the host immune system. Campylobacter jejuni is the leading bacterial 40 cause of diarrhea worldwide due to its near-ubiquitous zoonotic association with poultry. One of 41 the outstanding questions is to what extent the bacteria are responsible for the diarrheal 42 symptoms via intestinal cell necrosis versus immune cell initiated tissue damage. To determine 43 the stepwise process of inflammation that leads to diarrhea, we used a piglet ligated intestinal 44 loop model to study the intestinal response to C. jejuni. Pigs were chosen due to the anatomical 45 similarity between the porcine and the human intestine. We found that the abundance of 46 neutrophil related proteins increased in the intestinal lumen during C. jejuni infection, including 47 proteins related to neutrophil migration (neutrophil elastase and MMP9), actin reorganization 48 (Arp2/3), and antimicrobial proteins (lipocalin-2, myeloperoxidase, S100A8, and S100A9). The 49 appearance of neutrophil proteins also corresponded with increases of the inflammatory 50 cytokines IL-8 and TNF-a. Compared to infection with the C. jejuni wild-type strain, infection with 51 the noninvasive C. jejuni ?ciaD mutant resulted in a blunted inflammatory response, with less 52 inflammatory cytokines and neutrophil markers. These findings indicate that intestinal 53 inflammation is driven by C. jejuni virulence and that neutrophils are the predominant cell type 54 responding to C. jejuni infection. We propose that this model can be used as a platform to study 55 the early immune events during infection with intestinal pathogens.