Studies on the Effect of Neisserial Porins on Apoptosis of Mammalian Cells

Microorganisms or microbial products have been shown to induce or protect cells from activation-induced cell death or apoptosis (1 –3 ). Induction of apoptosis by some bacterial invaders, like shigella, might aid in spread of the organism (4 ), whereas inhibition of apoptosis by other microbes might aid in furthering their intracellular survival (2 ,3 ). Viral products have been shown to inhibit apoptosis by mimicking anti-apoptotic related proteins (e.g., Bcl2, FLIPS, etc.) (2 ,3 ,5 ). Thus far, most investigators have demonstrated that bacteria either have no effect or induce apoptosis of various cell types, mainly cells that they encounter upon invasion, e.g., epithelial cells, fibroblasts, and so on. Apoptotic cell death is also a key control mechanism of immune responses (6 ), but, to date, there have not been many investigations into the effect of microbes on apoptosis in immune cells. Dysregulation of immune cells associated with a lack of apoptosis and abnormal Fas-mediated cell death have been associated with immune dysfunction and hyperimmune states (7 ).