Pseudomonas aeruginosa triggered apoptosis of human epithelial cells depends on the temperature during infection

Abstract

The induction of apoptosis is a hallmark in many bacterial infections. Here, we show that the environmental temperature during infection influences P. aeruginosainduced apoptosis in human conjunctiva epithelial Chang cells. Infection with the clinical isolate P. aeruginosa762 at 37 degrees C resulted in a rapid induction of apoptosis within 30 min. Apoptosis was mediated by upregulation of CD95-receptor expression on the surface of the infected cells and depolarisation of the mitochondrial membrane potential (DeltaPhim) as determined by FACS-analysis of immunostained cells or of cells loaded with the potential sensitive dye JC1 respectively. In contrast, P. aeruginosafailed to induce significant apoptosis and mitochondrial alterations at 22 degrees C. The loss of the apoptotic response at 22 degrees C correlated with the failure of the epithelial cells to upregulate CD95, while bacterial growth or secretion of bacterial exotoxins into the culture supernatant appeared to be not affected. From our data we conclude that P. aeruginosa762 induced apoptosis is dependent on the temperature during infection and that cellular pathways leading to CD95-upregulation are inhibited at low temperature.