Translocation of Vibrio parahaemolyticus across an in vitro M cell model

Abstract

Consumption of Vibrio parahaemolyticus via contaminated shellfish results in inflammatory gastroenteritis characterised by severe diarrhoea, nausea and stomach cramps. This study investigated the translocation of V. parahaemolyticus across a Peyer's patch M cell-like Caco-2/Raji B co-culture model system, as M cells represent a primary site of infection for many pathogenic bacteria. Vibrio parahaemolyticus translocated across co-culture monolayers in higher numbers as compared to Caco-2 monolayers. Moreover, the bacteria induced a greater disruption of the transepithelial resistance in M cell-like co-cultures than in Caco-2 monocultures. Virulence factors associated with this pathogen include two type three secretion systems (TTSS-1 and TTSS-2). TTSS-1 had no effect on translocation efficiency, with TTSS-2 exhibiting a modest enhancing effect. ERK activity was required for optimal translocation 1 h postinfection, however, neither ERK nor the JNK and p38 MAPK were required at 2 h pi. Additionally, TER disruption in response to bacterial infection occurred independently of the TTSS and MAPK activation. It was concluded that V. parahaemolyticus causes TER disruption of M cell-like co-cultures and translocates in high numbers across the M cell-like co-culture monolayer. These data implicate M cells as important sites for V. parahaemolyticus invasion across the intestinal epithelium during infection.

Keywords: MAPK; bacterial virulence; gastroenteritis; microbial pathogenesis.