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% H₂ is adopted in TBI mice for 60 min, starting 1 and 6 h post-TBI. 24 h after H₂ inhalation, we extracted tissues and analyzed injury related changes. The H₂ 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% H₂. 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% H₂ provided better protection than either treatment alone.

Conclusions

2% H₂ can protect against TBI-induced lung injury by inhibiting NLRP3 inflammasome activation, thereby alleviating inflammation and inhibiting apoptosis.