Pseudomonas aeruginosa activates Cl- channels in host epithelial cells

Exposure to Pseudomonas aeruginosa triggers the apoptotic cell death of Chang epithelial cells, and this depends on the expression of both the CD95 receptor and CD95 ligand. In lymphocytes CD95-mediated apoptosis is paralleled by the activation of outwardly rectifying Cl- channels. The present study was performed to explore whether P. aeruginosa-induced apoptosis of Chang epithelial cells is paralleled by activation of Cl- channels. According to whole-cell patch-clamp recordings, exposure of Chang epithelial cells to P. aeruginosa does lead to rapid activation of an outwardly rectifying Cl- -selective current. The current is inhibited by the Cl- channel blocker NPPB. Exposure of Chang epithelial cells to P. aeruginosa led to a significant decrease of cell membrane capacitance by 6%, pointing to a decrease in cell volume by 7%. Exposure to P. aeruginosa depolarized the mitochondrial membrane potential indicating apoptotic cell death. The decline of mitochondrial membrane potential was not significantly affected by NPPB. In conclusion, P. aeruginosa-induced apoptosis of Chang epithelial cells is paralleled by activation of Cl- channels. Activation of the channels participates in the alteration of cell volume but is not a prerequisite for P. aeruginosa-induced apoptosis.