Background: Vibrio parahaemolyticus causes acute gastroenteritis and inflammations in humans. A variety of pathogenic bacteria can stimulate mitogen-activated protein kinases (MAPKs) in host cells. Phosphorylation of MAPKs leads to production of interleukin (IL)- 8 and subsequently causes inflammations. Thus, MAPK cascades were strong candidates for the main signaling pathway of V. parahaemolyticus-induced acute inflammation.
Methods: To determine whether the signaling pathway on V. parahaemolyticus infection induces inflammation, we analyzed the secretion level of IL-8 and phosphorylation of MAPKs by use of intestinal epithelial Caco-2 cells.
Results: V. parahaemolyticus infection of Caco-2 cells activated extracellular signal-regulated kinase (ERK) 1/2 and p38 MAPK signal pathways, leading to IL-8 secretion, whereas MAPK inhibitors, UO126 or SB203580, suppressed IL-8 secretion. A strain carrying a deletion of VP1680, a type three secretion system 1 (T3SS1) effector protein, failed to activate phosphorylation of ERK1/2 and p38 MAPK and secretion of IL-8. ERK1/2 pathway inhibitor, UO126, failed IL-8 promoter activity, whereas p38 MAPK inhibitor, SB203580, decreased the stabilization of IL-8 messenger RNA following V. parahaemolyticus infection.
Conclusions: We showed that V. parahaemolyticus infection of Caco-2 cells results in the secretion of IL-8, and that VP1680 plays a pivotal role in manipulating host cell signaling and is responsible for triggering IL-8 secretion.