Immune defense mechanisms in the Caenorhabditis elegans intestinal epithelium

Abstract

Intestinal epithelial cells provide an essential line of defense for Caernohabditis elegans against ingested pathogens. Because nematodes consume microorganisms as their food source, there has presumably been selection pressure to evolve and maintain immune defense mechanisms within the intestinal epithelium. Here we review recent advances that further define the immune signaling network within these cells and suggest mechanisms used by the nematode to monitor for infection. In reviewing studies of pathogenesis that use this simple model system, we hope to illustrate some of the basic principles of epithelial immunity that may also be of relevance in higher order hosts.

Figure 1

Features of C. elegans intestinal epithelial cells are strongly conserved. C. elegans intestinal epithelial cells bear a striking resemblance to human intestinal cells. Both cells have a brush border composed of microvilli (MV) anchored to a cellular structure called the terminal web (TW).This image was originally published by Troemel et al. [15] and is reproduced here with permission from Emily Troemel.

Figure 2

Multiple immune signaling pathways function in C. elegans epithelium. C. elegans coordinate pathogen-specific immune responses toward ingested pathogens through several signaling pathways that act in parallel. The transcriptional outputs from these signaling mediators are unique, but can be overlapping.