Inflammatory Signaling Induces Mitochondrial Dysfunction and Neuronal Death in Traumatic Brain Injury via Downregulation of OXPHOS Genes.

Abstract

Traumatic brain injury (TBI) is a major cause of neurological dysfunction and disability. This study aimed to investigate the transcriptomic changes and the functional consequences in TBI, focusing on the interplay between inflammation and mitochondrial impairment. Brain tissue samples from TBI patients and healthy controls were subjected to RNA-sequencing analysis. Mouse hippocampal HT-22 cells were treated with inflammatory cytokine and the PGC-1α activator ZLN005. Mitochondrial function, oxidative stress, and apoptosis were assessed using Seahorse respirometry, electron microscopy, flow cytometry, and molecular assays. A TBI mouse model was established to evaluate the therapeutic effects of ZLN005. Transcriptome profiling revealed downregulation of mitochondrial oxidative phosphorylation (OXPHOS) genes, particularly those encoded by the mitochondrial genome, along with enrichment of neurodegenerative pathways in TBI patients. Concomitantly, pro-inflammatory signaling pathways showed upregulation. In vitro studies demonstrated that inflammatory cytokine TNF-α treatment impaired mitochondrial respiration, induced oxidative stress and apoptosis in HT-22 cells, which could be rescued by ZLN005-mediated PGC-1α activation and restoration of OXPHOS gene expression. Administration of ZLN005 in the TBI mouse model alleviated neuronal cell death, preserved mitochondrial integrity, normalized OXPHOS gene levels in brain tissues, and improved cognitive function. This study uncovers a mechanistic link between inflammation-induced downregulation of mitochondrial OXPHOS genes and neuronal damage in TBI. Targeting this pathway by activating PGC-1α represents a potential therapeutic strategy for TBI.