Nav1.3 inhibition confers neuroprotection in traumatic brain injury by attenuating neuroinflammation and neuronal cell death via NCOA4-associated ferritin turnover.

Abstract

Our previous investigations using antisense-mediated knockdown supported a pathogenic role for the voltage-gated sodium channel isoform Nav1.3 in traumatic brain injury (TBI), yet its downstream mechanisms remain incompletely defined. Here, we observed concurrent elevation of Nav1.3 mRNA and Ca²⁺ in human brain tissues following TBI. Pharmacological inhibition of Nav1.1/Nav1.3 with ICA-121431 in a controlled cortical impact (CCI) mouse model significantly ameliorated neurological deficits, reduced cerebral edema, downregulated neuronal injury markers (Iba-1, GFAP and iNOS) and pro-inflammatory cytokine (IL-1α, IL-3, IL-6) while upregulating anti-inflammatory IL-13. Notably, ICA-121431 combined with the anti-seizure agent levetiracetam conferred no extra benefit over ICA-121431 monotherapy. In vitro, ICA-121431 protected HT-22 neurons from stretch-induced death, increased FTH1 expression, and decreased NCOA4 levels and LC3BII/I ratio. Lysosomal inhibitor Bafilomycin A1 further elevated both LC3-II/I and FTH1 in injured neurons, confirming that the stretch-induced LC3-II/I rise represents enhanced autophagic flux rather than degradation block. Importantly, combining ICA-121431 with the mitochondrial Na⁺/Ca²⁺ exchanger (mNCX) inhibitor ITH12575 yielded greater neuroprotective effects than ICA-121431 alone. Lysosomal blockade failed to induce further accumulation of FTH1 or LC3-II in this combination group, indicating marked attenuation of NCOA4-associated ferritin turnover. Consistently, NCOA4 knockdown recapitulated this protection and restored FTH1 after stretch injury, supporting NCOA4-associated neuronal cell death. Collectively, Nav-channel inhibitor ICA-121431 improved neurological outcomes of TBI mice through reducing neuroinflammation. Concurrent inhibition of Nav-channels and mNCX yielded enhanced in-vitro protection linked to attenuated NCOA4-associated ferritin turnover. These insights provided a mechanistic basis for novel TBI therapeutic strategies targeting sodium‑calcium homeostasis.