S. aureushaemolysin 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

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.

Staphylococcus aureusα-toxin-mediated cation entry depolarizes membrane potential and activates p38 MAP kinase in airway epithelial cells

“…As previously shown in different cell types (34,50) including airway epithelial cells (14,43), [Ca 2ϩ ] i increases upon exposure of cells to Hla. These observations were confirmed in this study.…”

“…Addition of rHla to the extracellular medium of such cells induces elevations in [Ca 2ϩ ] i (14,50) and may increase membrane permeability for monovalent cations (31,58). This may directly or indirectly affect ciliary beat frequency, fluid and mucus secretion, or the release of proinflammatory cytokines and chemokines (7,11,15,33,39,43,51). These functional changes are supposed to represent defensive actions of the epithelial cells against the bacteria (32).…”

“…Western blotting for the quantification of the core or the phosphorylated proteins was performed using phospho-specific antibodies, HRP-linked secondary antibodies (1: 6,000), and enhanced luminescence reagents (Biozym, Oldendorf, Germany). Specificity of antibody binding has been shown previously (19,43). Signals were recorded using a Fusion SL 3500.WL gel imager (Vilbert Lourmat, Eberhardzell, Germany).…”

“…Treatment of eukaryotic cells with Hla elicits various cell physiological effects ranging from apoptotic or necrotic cell death (16) or survival signaling (24,43) to changes in cell-cell or cell-matrix adhesion and actin cytoskeleton reorganization (19,60). Studies using cultured airway epithelial cells revealed that they respond to Hla treatment with ADAM10-mediated cleavage of cadherin (25).…”

“…Hla treatment of airway epithelial cells results in activation of ADAM10 (60), which may affect several subsequent signaling modules by as yet unknown links in the transduction pathways including proinflammatory pathways (13). However, ADAM10 activation depends on the presence of extracellular calcium (25) and on calcium influx into the cytosol (23 (4,19,43), but the modes of activation are still elusive. The aim of this study was to elucidate whether mono-or divalent cations can pass through the Hla pores in otherwise intact epithelial cells and whether Hla-mediated changes in the cytosolic concentrations of mono-or divalent cations are sufficient to activate intracellular signaling pathways affecting the above mentioned cellular processes.…”