Inhibiting oxidative stress and inflammation in acute lung injury using hydrogen: A preclinical systematic review and meta-analysis

Acute lung injury (ALI) results from excessive inflammation and disruption of the alveolar-capillary barrier, leading to acute respiratory distress syndrome. Hydrogen, known as a reducing substance, has been commonly used in preclinical trials of ALI. The present paper aims to summarize the effects of hydrogen on animal models of ALI and the possible antioxidant and anti-inflammation mechanisms of hydrogen. We conducted a thorough search of the relevant literature on PubMed, EMBASE, Web of Science, and CNKI. Data retrieved from 20 studies were analyzed to assess the beneficial effects of hydrogen therapy on ALI animal models. To evaluate the effects of hydrogen, commonly assessed outcome indicators include wet-to-dry ratio (W/D), arterial oxygen partial pressure (PaO2), malondialdehyde (MDA), superoxide dismutase (SOD), and tumor necrosis factor-alpha (TNF-α). The results demonstrate that hydrogen reduces pulmonary edema (W/D: 95% CI = −0.98 – −0.85, P < 0.001), mitigates hypoxia (PaO2: 95% CI = 6.08 – 22.30, P < 0.001), represses lipid peroxidation (MDA: 95% CI = −2.12 – −1.06, P < 0.001), scavenges free radicals (SOD: 95% CI = 10.12 – 30.07, P < 0.001), and inhibits inflammatory response (TNF-α: 95% CI = −5.52 – −1.72, P < 0.001). The subgroup analysis showed significant differences between interventions (MDA: P < 0.05; TNF-α: P < 0.05; SOD: P < 0.001). The meta-regression suggests that species may cause heterogeneity (P < 0.05). These results suggest the potential of using hydrogen in clinical trials. Different interventions with hydrogen can affect metabolic transport and distribution in vivo. Further studies should be conducted to validate and confirm these findings.