Hydrogen gas alleviates lipopolysaccharide-induced acute lung injury and inflammatory response in mice

Abstract:

Background: Chronic inflammation and oxidant/antioxidant imbalance are two main pathological features associated with lipopolysaccharide (LPS)-induced acute lung injury (ALI). The following study investigated the protective role of hydrogen (H2), a gaseous molecule without known toxicity, in LPS-induced lung injury in mice and explored its potential molecular mechanisms.

Methods: Mice were randomly divided into three groups: H2 control group, LPS group, and LPS + H2 group. The mice were euthanized at the indicated time points, and the specimens were collected. The 72 h survival rates, cytokines contents, pathological changes, expression of Toll-like receptor 4 (TLR4), and oxidative stress indicators were analyzed. Moreover, under different culture conditions, RAW 264.7 mouse macrophages were used to investigate the potential molecular mechanisms of H2 in vitro. Cells were divided into the following groups: PBS group, LPS group, and LPS + H2 group. The cell viability, intracellular ROS, cytokines, and expression of TLR4 and nuclear factor kappa-B (NF-κB) were observed.

Results: Hydrogen inhalation increased the survival rate to 80%, reduced LPS-induced lung damage, and decreased inflammatory cytokine release in LPS mice. Besides, H2 showed remarked anti-oxidative activity to reduce the MDA and NO contents in the lung. In vitro data further indicated that H2 down-regulates the levels of ROS, NO, TNF-α, IL-6, and IL-1β in LPS-stimulated macrophages and inhibits the expression of TLR4 and the activation of nuclear factor kappa-B (NF-κB).

Conclusion: Hydrogen gas alleviates lipopolysaccharide-induced acute lung injury and inflammatory response most probably through the TLR4-NF-κB pathway.