Molecular hydrogen mitigates traumatic brain injury-induced lung injury via NLRP3 inflammasome inhibition.

INTRODUCTION: Hydrogen gas has demonstrated significant antioxidant and anti-inflammatory properties, suggesting potential therapeutic benefits in TBI. METHODS: We subjected to controlled cortical impact in mice to construct TBI model. They received an intraperitoneal injection of MCC950, a selective NLRP3 inhibitor, at 10 mg/kg 30 min before TBI. Inhalation of 2% H(2) is adopted in TBI mice for 60 min, starting 1 and 6 h post-TBI. 24 h after H(2) inhalation, we extracted tissues and analyzed injury related changes. The H(2) levels in arterial and venous were tracked after inhalation. Lung tissue was examined for histopathological changes and apoptosis using H&E and TUNEL assays. The total protein in the BALF, oxygenation index, lung wet-to-dry weight ratio, and lung MPO activity were measured to evaluate the severity of TBI-induced lung injury. Protein and mRNA levels of NLRP3, ASC, Caspase-1, IL-18, and IL-1β in the lung tissue were quantified using western blotting and quantitative PCR. The expression changes and distribution status of NLRP3 and Caspase-1 were examined by immunofluorescence and immunohistochemistry staining. RESULTS: Significant lung injury at 24 h post-TBI got significantly reduced by treatment of 2% H(2). TBI activated the NLRP3 inflammasome, increasing NLRP3, ASC, and caspase-1 levels, to lead to higher IL-1β and IL-18 secretion in the lungs. Blocking NLRP3 reduced lung damage from TBI, and its combination with 2% H(2) provided better protection than either treatment alone. CONCLUSIONS: 2% H(2) can protect against TBI-induced lung injury by inhibiting NLRP3 inflammasome activation, thereby alleviating inflammation and inhibiting apoptosis.