title: Autophagy in innate immunity against intracellular bacteria.
abstract: Many pathogenic bacteria can invade phagocytic and non-phagocytic cells and colonize them intracellularly, then become disseminated to other cells. The endocytic degradation pathway is thought to be the only prevention against such intracellular pathogens. Autophagy, a fundamental cellular homeostasis pathway that operates with the intracellular degradation/recycling system, causes the turnover of cellular components by delivering portions of the cytoplasm and organelles to lysosomes. Recently, we reported that autophagic degradation is a previously unrecognized effector of host innate immunity. Streptococcus pyogenes (Group A Streptococcus; GAS) successfully enters human epithelial cells via endocytosis. GAS immediately escapes from the endosomes to the cytoplasm and gains a replicative niche, after which GAS in the cytoplasm is trapped in autophagosome-like compartments and degraded upon fusion with lysosomes. This process indicates that autophagy plays a protective role in infectious diseases. We also found that autophagic degradation was induced against Staphylococcus aureus, while methicillin-resistant S. aureus were resistant to autophagic degradation. The present review focuses on the protective function of autophagy against bacterial invasion of cells.
authors.affiliation: Department of Oral Frontier Biology, Osaka University Graduate School of Dentistry, Suita-Osaka. amanoa@dent.osaka-u.ac.jp
authors.forename: Atsuo
authors.initials: A
authors.lastname: Amano
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakagawa
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Yoshimori
mesh_terms: D001343:Autophagy / Q000502:physiology*; D007113:Immunity, Innate / Q000502:physiology*; D013290:Streptococcal Infections / Q000378:metabolism; D013297:Streptococcus pyogenes / Q000502:physiology*