Inhaled hydrogen sulfide protects against lipopolysaccharide-induced acute lung injury in mice

Background: Local pulmonary and systemic infections can lead to acute lung injury (ALI). The resulting lung damage can evoke lung failure and multiple organ dysfunction associated with increased mortality. Hydrogen sulfide (H2S) appears to represent a new therapeutic approach to ALI. The gas has been shown to mediate potent anti-inflammatory and organ protective effects in vivo. This study was designed to define its potentially protective role in sepsis-induced lung injury. Methods: C57BL/6 N mice received lipopolysaccharide (LPS) intranasally in the absence or presence of 80 parts per million H2S. After 6 h, acute lung injury was determined by comparative histology. Bronchoalveolar lavage (BAL) fluid was analyzed for total protein content and differential cell counting. BAL and serum were further analyzed for interleukin-1 beta, macrophage inflammatory protein-2, and/or myeloperoxidase glycoprotein levels by enzyme-linked immunosorbent assays. Differences between groups were analyzed by one way analysis of variance. Results: Histological analysis revealed that LPS instillation led to increased alveolar wall thickening, cellular infiltration, and to an elevated ALI score. In the presence of H2S these changes were not observed despite LPS treatment. Moreover, neutrophil influx, and pro-inflammatory cytokine release were enhanced in BAL fluid of LPS-treated mice, but comparable to control levels in H2S treated mice. In addition, myeloperoxidase levels were increased in serum after LPS challenge and this was prevented by H2S inhalation. Conclusion: Inhalation of hydrogen sulfide protects against LPS-induced acute lung injury by attenuating pro-inflammatory responses.