RESUMO
Ferroptosis is a redox-driven type of regulated cell death program arising from maladaptation of three metabolic pathways: glutathione homeostasis, iron handling and lipid peroxidation. Though GSH/Gpx4 is the predominant system detoxifying phospholipid hydroperoxides (PLOOH) in mammalian cells, recently Gpx4-independent regulators of ferroptosis like ferroptosis suppressor protein 1 (FSP1) in resistant cancer lines and iNOS/NO⢠in M1 macrophages have been discovered. We previously reported that Pseudomonas aeruginosa (PA) utilizes its 15- lipoxygenase (pLoxA) to trigger ferroptotic death in epithelial cells by oxidizing the host arachidonoyl-phosphatidylethanolamine (ETE-PE) into pro-ferroptotic 15-hydroperoxy- arachidonyl-PE (15-HpETE-PE). Here we demonstrate that PA degrades the host GPx4 defense by activating the lysosomal chaperone-mediated autophagy (CMA). In response, the host stimulates the iNOS/NOâ¢-driven anti-ferroptotic mechanism to stymie lipid peroxidation and protect GPx4/GSH-deficient cells. By using a co-culture model system, we showed that macrophage-produced NO⢠can distantly prevent PA stimulated ferroptosis in epithelial cells as an inter-cellular mechanism. We further established that suppression of ferroptosis in epithelial cells by NO⢠is enabled through the suppression of phospholipid peroxidation, particularly the production of pro-ferroptotic 15-HpETE-PE signals. Pharmacological targeting of iNOS (NO⢠generation) attenuated its anti-ferroptotic function. In conclusion, our findings define a new inter-cellular ferroptosis suppression mechanism which may represent a new strategy of the host against P. aeruginosa induced theft-ferroptosis.
Assuntos
Ferroptose , Animais , Peroxidação de Lipídeos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Pseudomonas aeruginosa , Compostos de Sulfidrila , RouboRESUMO
Ferroptotic death is the penalty for losing control over three processes-iron metabolism, lipid peroxidation and thiol regulation-that are common in the pro-inflammatory environment where professional phagocytes fulfill their functions and yet survive. We hypothesized that redox reprogramming of 15-lipoxygenase (15-LOX) during the generation of pro-ferroptotic signal 15-hydroperoxy-eicosa-tetra-enoyl-phosphatidylethanolamine (15-HpETE-PE) modulates ferroptotic endurance. Here, we have discovered that inducible nitric oxide synthase (iNOS)/NOâ¢-enrichment of activated M1 (but not alternatively activated M2) macrophages/microglia modulates susceptibility to ferroptosis. Genetic or pharmacologic depletion/inactivation of iNOS confers sensitivity on M1 cells, whereas NO⢠donors empower resistance of M2 cells to ferroptosis. In vivo, M1 phagocytes, in comparison to M2 phagocytes, exert higher resistance to pharmacologically induced ferroptosis. This resistance is diminished in iNOS-deficient cells in the pro-inflammatory conditions of brain trauma or the tumour microenvironment. The nitroxygenation of eicosatetraenoyl (ETE)-PE intermediates and oxidatively truncated species by NO⢠donors and/or suppression of NO⢠production by iNOS inhibitors represent a novel redox mechanism of regulation of ferroptosis in pro-inflammatory conditions.