Hydrogen inhalation attenuates lung contusion after blunt chest trauma in mice

Background: Lung contusion caused by blunt chest trauma evokes a severe inflammatory reaction in the pulmonary parenchyma that may be associated with acute respiratory distress syndrome. Although hydrogen gas has antioxidant and anti-inflammatory effects and is protective against multiple types of lung injury at safe concentrations, the effects of inhaled hydrogen gas on blunt lung injury have not been previously investigated. Therefore, using a mouse model, we tested the hypothesis that hydrogen inhalation after chest trauma would reduce pulmonary inflammation and acute lung injury associated with lung contusion. Methods: Inbred male C57BL/6 mice were randomly divided into 3 groups: sham with air inhalation, lung contusion with air inhalation, and lung contusion with 1.3% hydrogen inhalation. Experimental lung contusion was induced using a highly reproducible and standardized apparatus. Immediately after induction of lung contusion, mice were placed in a chamber exposed to 1.3% hydrogen gas in the air. Histopathological analysis and real-time polymerase chain reaction in lung tissue and blood gas analysis were performed 6 hours after contusion. Results: Histopathological examination of the lung tissue after contusion revealed perivascular/intra-alveolar hemorrhage, perivascular/interstitial leukocyte infiltration, and interstitial/intra-alveolar edema. These histological changes and the extent of lung contusion, as determined by computed tomography, were significantly mitigated by hydrogen inhalation. Hydrogen inhalation also significantly reduced inflammatory cytokine and chemokine mRNA levels and improved oxygenation. Conclusion: Hydrogen inhalation therapy significantly mitigated inflammatory responses associated with lung contusion in mice. Hydrogen inhalation therapy may be a supplemental therapeutic strategy for treating lung contusion.

Intraperitoneally administered, hydrogen-rich physiologic solution protects against postoperative ileus and is associated with reduced nitric oxide production

Background: Postoperative ileus, a transient impairment of bowel motility initiated by intestinal inflammation, is common after an abdominal operation and leads to increased hospital stays and costs. Hydrogen has potent anti-inflammatory and antioxidant properties and potential therapeutic value. Solubilized hydrogen may be a portable and practical means of administering therapeutic hydrogen gas. We hypothesized that intraperitoneal administration of hydrogen-rich saline would ameliorate postoperative ileus. Methods: Ileus was induced via surgical manipulation in mice and rats. The peritoneal cavity was filled with 1.0 mL saline or hydrogen-rich saline (≥1.5-2.0 ppm) before closure of the abdominal incision. Intestinal transit was assessed 24 hours postoperatively. Inflammation was examined by quantitation of neutrophil extravasation and expression of proinflammatory markers. Nitric oxide production was assessed in cultured muscularis propria. Results: Surgical manipulation resulted in a marked delay in intestinal transit and was associated with upregulation of proinflammatory cytokines and increased neutrophil extravasation. Bowel dysmotility, induced by surgical manipulation and inflammatory events, was significantly attenuated by intra-abdominal administration of hydrogen-rich saline. Nitric oxide production in the muscle layers of the bowel was inhibited by hydrogen treatment. Conclusion: A single intraperitoneal dose of hydrogen-rich saline ameliorates postoperative ileus by inhibiting the inflammatory response and suppressing nitric oxide production.

Hydrogen gas inhalation ameliorates lung injury after hemorrhagic shock and resuscitation

Background: Hemorrhagic shock and resuscitation (HSR) is known to cause inflammatory reactions in the lung parenchyma and acute lung injury, increasing the risk of complications that can lead to death. Hydrogen gas has shown to inhibit the formation and eliminate reactive oxygen species (ROS), which are known to cause reperfusion injury. Hence, the purpose of this study was to investigate the protective effect of 2% inhaled hydrogen gas on post-HSR lung injury. Methods: Rats weighing 300-500 g were divided into three groups: sham, HSR, and hydrogen (H2)/HSR groups. In the latter two groups, HSR was induced via femoral vein cannulation. Gas containing 2% hydrogen gas was inhaled only by those in the H2/HSR group. Lung tissue and abdominal aorta blood were obtained for histologic examination and arterial blood gas analyses, respectively. Neutrophil infiltration and proinflammatory mediators were also measured. Results: PO2 was lower in the HSR and H2/HSR groups than in the sham group. Blood lactate level was not significantly different between the sham and H2/HSR groups, but it was significantly higher in the HSR group. Infiltration of inflammatory cells into the lung tissues was more frequent in the HSR group. Myeloperoxidase (MPO) activity was significantly different among the three groups (highest in the HSR group). All proinflammatory mediators, except IL-6, showed a significant difference among the three groups (highest in the HSR group). Conclusions: Inhalation of 2% hydrogen gas after HSR minimized the extent of lung injury by decreasing MPO activity and reducing infiltration of inflammatory cells into lung tissue.