The NF-kappaB p50 subunit is protective during intestinal Entamoeba histolytica infection of 129 and C57BL/6 mice.

Entamoeba histolytica is the agent of amebic colitis. In this work we examined the intestinal NF-kappaB response to this parasite. Using an enzyme-linked immunosorbent assay (ELISA) and an electrophoretic mobility shift assay, we found that the NF-kappaB subunit p50 predominated in nuclear extracts of whole cecal tissue and of isolated crypts from mice inoculated with E. histolytica. p50 was protective, since C57BL/6 and 129 mice in which there was targeted deletion of this subunit were more susceptible to E. histolytica infection as measured by culture results, cecal parasite ELISA results, and/or histologic scores. The transepithelial electrical resistance of cecal explants from C57BL/6 and 129 p50 knockout mice decreased markedly in response to the parasite compared with the transepithelial electrical resistance of their wild-type counterparts, suggesting that a protective function of p50 was present in the epithelium itself. This work shows that NF-kappaB activity, particularly activity of the p50 subunit, is one factor that contributes to resistance of the gut to E. histolytica infection.