S. aureus haemolysin A-induced IL-8 and IL-6 release from human airway epithelial cells is mediated by activation of p38- and Erk-MAP kinases and additional, cell type-specific signalling mechanisms

Abstract

Soluble virulence-associated factors of Staphylococcus aureus like haemolysin A (Hla) induce secretion of chemo/cytokines from airway epithelial cells. To elucidate the potential roles of specific signalling pathways in this response, we treated 16HBE14o-, S9 or A549 cells with recombinant Hla (rHla). In a dose-dependent manner, rHla induced secretion of IL-8 in all three cell types, but IL-6 release only in 16HBE14o- and S9 cells. rHla-mediated secretion of IL-8 and IL-6 was suppressed by pre-incubation of cells with inhibitors of Erk type or p38 MAP kinases, indicating that activation of these signalling pathways is essential for IL-8 release in all three cell types and for IL-6 release in 16HBE14o- and S9 cells. The rHla-mediated phosphorylation and activation of p38 MAP kinase seem to depend on elevations in [Ca(2+)]i, an early response in rHla-treated cells. Inhibitors of calmodulin or calcium/calmodulin-dependent kinase II attenuated rHla-mediated release of IL-8 in 16HBE14o- and A549 cells and of IL-6 in 16HBE14o- cells. This indicates that rHla may mediate simultaneous activation of calmodulin-dependent processes as additional prerequisites for chemo/cytokine secretion.However, the inhibitors of calmodulin-dependent signalling did not affect rHla-induced p38 MAP kinase phosphorylation, indicating that this pathway works in parallel with p38 MAP kinase.