Bacterial strategies for escaping the bactericidal mechanisms by macrophage

Abstract

Phagocytosis with macrophages provides a specialized mechanism for regulated ingestion and intracellular destruction of bacteria. Bacteria are first engulfed by endocytosis into a phagosome. The fusion of phagosomes and lysosomes releases toxic products that kill most bacteria and degrade them into fragments. Debris from dead bacteria is then released by exocytosis. However, some bacteria that survive within host phagocytes have evolved strategies to escape the bactericidal mechanisms associated with phagocytosis: i) antiphagocytosis (Yersinia), ii) escaping from the phagosome into cytoplasm (Listeria), and iii) remodeling their phagosome by inhibiting the maturation of phagosomes (Salmonella, Mycobacterium, Legionella). In this review, I first summarize various strategies by bacteria to avoid phagocytosis by emphasizing the steps that have been subverted by bacteria. Then, I highlight the mechanisms for surviving phagocytosis by Salmonella, with a focus on the induction of macrophage-apoptosis and modulation of membrane traffic in host cells. © 2006 The Pharmaceutical Society of Japan.