ALOX15 Knockdown Mitigates Hypoxia and Hypobaric-induced Heart Injury and Ferroptosis via p53-SAT1 signaling pathway

Acute mountain sickness is one of public health problem caused by hypobaric and hypoxia (HH). More than 100 million people move from plain area to plateau worldwide every year and 10–85% of these individuals suffer from acute mountain sickness (AMS), which induces multiple organ damage including heart. However, only scanty mechanism information is available on acute altitude-induced heart injuries. In this study, we sought to investigate the association between hypobaric hypoxia induced heart injury and inflammatory response and ferroptosis process. In this study, rats were subjected to a low-pressure hypoxic chamber to establish hypobaric hypoxia model. H&E staining, immunofluorescence and electron microscopy were conducted to investigate myocardium injury. Flow cytometry and Rat 23-Plex Cytokine chip were analyzed changes of monocyte subtypes and cytokines concentration. RNA-seq and targeted metabolomics method were applied to identified key genes and metabolites. ALOX15-deficient rats were used to elucidate the functional roles of ALOX15 and its metabolites of 12/15-sHETE in HH-induced heart injury. Right ventricular injury accompanied by significant inflammatory damage of rats occured during acute HH exposure, especially in 3 day. Proinflammatory M1 macrophage increased after HH exposure, and classical monocytes subset ( Ly6c+) both increased significantly in blood and bone marrow, but decreased significantly in bone marrow. HH enhance the expression of GM-CSF, IL-10, IL-18, IL-2 ,IL-7, MIP-1αand CCL5 in myocardium. Mechanically, ALOX15 and its metabolites of 12/15-sHETE highly expression in myocardium, which triggered ferroptosis in endothelial cells of heart, and in turn contributed to inflammatory injury of myocardial tissue. In addition, pathway-based screening results show that ALOX15 was upregulated through p53-SAT1 pathway. Conversely, heart specific knockdown of ALOX15 in rat inhibited endothelial cells ferroptosis through ACSL4-LPCAT3 pathways, and reduce the number of monocytes. Likewise, decreased secretion of 12/15s-HETE significantly reduced ROS accumulation in endothelial cells thereby protected the inflammatory injured in myocardium. Together, our results established that ALOX15 and 12/15s-HETE mediated endothelial cells ferroptosis causing myocarditis damage after hypoxia and hypobaric exposure.