Anaerobiosis-induced virulence of Salmonella enterica subsp. enterica serovar Typhimurium: role of phospholipase Cgamma signalling cascade.

Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) can initiate entry into non-phagocytic epithelial cells by triggering certain signal transduction pathways, thereby allowing the pathogen to invade and establish a niche within host cells. Anaerobiosis has been shown to be an important inducer of the invasion process of S. Typhimurium. However, the effect of anaerobiosis on modulation of cell signalling cascades by S. Typhimurium is not known. In the present study, the phospholipase Cgamma signalling cascade was investigated in mice enterocytes, following interaction with S. Typhimurium grown under aerobic and anaerobic growth conditions. Significant increases in enterocyte intracellular calcium and inositol 1,4,5-triphosphate levels were observed on interaction with S. Typhimurium grown anaerobically compared with S. Typhimurium grown aerobically. An increased membrane/cytosolic ratio of protein kinase C was also seen with anaerobic S. Typhimurium in enterocytes compared with aerobic S. Typhimurium. These data suggest that anaerobically grown organisms are more efficient in initiating cell-signalling events than are aerobically grown bacteria. These enhanced cell signals may contribute to the increased virulence of S. Typhimurium grown anaerobically.