Trichuris muris resides in intimate contact with its host, burrowing within cecal epithelial cells. However, whether the enterocyte itself responds innately to T. muris is unknown. This study investigated for the first time whether colonic intestinal epithelial cells (IEC) produce cytokines or chemokines following T. muris infection and whether divergence of the innate response could explain differentially polarized adaptive immune responses in resistant and susceptible mice. Increased expression of mRNA for the proinflammatory cytokines gamma interferon (IFN-γ) and tumor necrosis factor and the chemokine CCL2 (MCP-1) were seen after infection of susceptible and resistant strains, with the only difference in expression being a delayed increase in CCL2 in BALB/c IEC. These increases were ablated in MyD88 -/- mice, and NF-κBB p65 was phosphorylated in response to T. muris excretory/secretory products in the epithelial cell line CMT-93, suggesting involvement of the MyD88-NF-κB signaling pathway in IEC cytokine expression. These data reveal that IEC respond innately to T. muris. However, the minor differences identified between resistant and susceptible mice are unlikely to underlie the subsequent development of a susceptible type 1 (IFN-γ-dominated) or resistant type 2 (interleukin-4 [IL-4]/IL-13- dominated) adaptive immune response. Copyright © 2006, American Society for Microbiology. All Rights Reserved.