Butyrate protects Caco-2 cells from Campylobacter jejuni invasion and translocation

Invasion in and translocation across enterocytes are major events during Campylobacter jejuni-induced enteritis in humans. C. jejuni in vitro infection of cell monolayers typically results in loss of tight junction integrity, which could contribute to translocation. In the present study, we wanted to investigate whether butyrate is able to confer protection to Caco-2 cells against C. jejuni invasion, thus reducing paracellular permeability and limiting C. jejuni translocation. Protection of Caco-2 cells against C. jejuni invasion was assessed using a gentamicin protection assay. Transwell systems were used to investigate the impact of butyrate on translocation of C. jejuni across a Caco-2 monolayer and its effect on transepithelial resistance during infection. Butyrate protected Caco-2 cells against C. jejuni invasion in a concentration-dependent manner. Differentiated Caco-2 cells were less susceptible to C. jejuni invasion than 3-d-old undifferentiated cells and higher concentrations of butyrate and longer incubation times were needed to become refractive for invasion. C. jejuni translocation over Caco-2 monolayers was reduced when monolayers were treated with butyrate and this was accompanied by an enhanced drop in transepithelial resistance. The present study showed that butyrate is able to protect Caco-2 cells from two major virulence mechanisms of C. jejuni, namely invasion and translocation, but not from a decline in transepithelial resistance.