Integrated transcriptomics and metabolomics confirms the oxidative stress mechanism of hypothermia-induced neuronal necroptosis.

Abstract

Abnormal climate change seriously endangers the safety of outdoor work and life, often causing hypothermia-induced coma or death. As the underlying mechanism has not been fully elucidated, a targeted treatment for hypothermia-triggered neuronal injury and forensic pathology indicators of fatal hypothermia are lacking. Herein, we aimed to explore hypothermia-induced changes in gene expression and metabolite profiles of cerebral cortical tissues to elucidate the mechanism of hypothermia-promoted necroptosis of cerebral cortical neurons. Flow cytometry and fluoro-jade C staining showed that low temperature caused necroptosis of cerebral cortical neurons. Transcriptomics identified 244 differential genes between hypothermia-exposed cortical tissue and control tissue. These genes were enriched in tumor necrosis factor (TNF)-α and nuclear factor (NF)-kappa B signaling pathways, as revealed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Broadly targeted metabolomics identified 49 differential metabolites with significant differences. N-alpha-acetyl-L-arginine, argininosuccinic acid, glutaric acid, and other ornithine cycle-associated metabolites were significantly reduced in the hypothermia-exposed cortical tissue, driving fumaric acid reduction in the tricarboxylic acid (TCA) cycle. In addition, KEGG enrichment analysis showed significant changes in the TCA cycle pathway. A combined transcriptomic and metabolomic analysis uncovered that hypothermia induced oxidative stress through NF-κB activation, caused mitochondrial damage, impaired the ornithine cycle, and, ultimately, induced neuronal necroptosis. Pharmacological inhibition of NF-κB by the SC75741 inhibitor effectively ameliorated hypothermia-triggered necroptosis. In conclusion, our results suggest that the NF-κB transcription factor is a potential marker of hypothermia-induced neuronal necroptosis in the mouse cerebral cortex. In addition, our findings indicate the mechanism of necroptosis in cerebral cortical neurons caused by low temperature, which is beneficial for our understanding of hypothermia-induced coma and death.