title: Mycobacterium tuberculosis eis regulates autophagy, inflammation, and cell death through redox-dependent signaling.
abstract: The "enhanced intracellular survival" (eis) gene of Mycobacterium tuberculosis (Mtb) is involved in the intracellular survival of M. smegmatis. However, its exact effects on host cell function remain elusive. We herein report that Mtb Eis plays essential roles in modulating macrophage autophagy, inflammatory responses, and cell death via a reactive oxygen species (ROS)-dependent pathway. Macrophages infected with an Mtb eis-deletion mutant H37Rv (Mtb-Δeis) displayed markedly increased accumulation of massive autophagic vacuoles and formation of autophagosomes in vitro and in vivo. Infection of macrophages with Mtb-Δeis increased the production of tumor necrosis factor-α and interleukin-6 over the levels produced by infection with wild-type or complemented strains. Elevated ROS generation in macrophages infected with Mtb-Δeis (for which NADPH oxidase and mitochondria were largely responsible) rendered the cells highly sensitive to autophagy activation and cytokine production. Despite considerable activation of autophagy and proinflammatory responses, macrophages infected with Mtb-Δeis underwent caspase-independent cell death. This cell death was significantly inhibited by blockade of autophagy and c-Jun N-terminal kinase-ROS signaling, suggesting that excessive autophagy and oxidative stress are detrimental to cell survival. Finally, artificial over-expression of Eis or pretreatment with recombinant Eis abrogated production of both ROS and proinflammatory cytokines, which depends on the N-acetyltransferase domain of the Eis protein. Collectively, these data indicate that Mtb Eis suppresses host innate immune defenses by modulating autophagy, inflammation, and cell death in a redox-dependent manner.
authors.affiliation: Department of Microbiology, College of Medicine, Chungnam National University, Daejeon, Korea.
authors.forename: Dong-Min
authors.initials: DM
authors.lastname: Shin
authors.forename: Bo-Young
authors.initials: BY
authors.lastname: Jeon
authors.forename: Hye-Mi
authors.initials: HM
authors.lastname: Lee
authors.forename: Hyo Sun
authors.initials: HS
authors.lastname: Jin
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Yuk
authors.forename: Chang-Hwa
authors.initials: CH
authors.lastname: Song
authors.forename: Sang-Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Zee-Won
authors.initials: ZW
authors.lastname: Lee
authors.forename: Sang-Nae
authors.initials: SN
authors.lastname: Cho
authors.forename: Jin-Man
authors.initials: JM
authors.lastname: Kim
authors.forename: Richard L
authors.initials: RL
authors.lastname: Friedman
authors.forename: Eun-Kyeong
authors.initials: EK
authors.lastname: Jo
mesh_terms: D000123:Acetyltransferases; D000818:Animals; D000942:Antigens, Bacterial / Q000502:physiology*; D001343:Autophagy; D001426:Bacterial Proteins / Q000502:physiology*; D016923:Cell Death; D054884:Host-Pathogen Interactions / Q000276:immunology*; D007113:Immunity, Innate; D007249:Inflammation; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; D000123:Acetyltransferases; C430563:Eis protein, Mycobacterium tuberculosis