Background. Hydrogen-rich saline (HRS) has strong anti-inflammatory, antioxidative stress, and antiapoptotic properties. The study focused on the protection of HRS on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rat models and the relationship with autophagic regulation and mTOR/TFEB signaling pathway. Material and Methods. The LPS-induced ALI rats’ model was established. Pathohistological change in lung tissue was detected by hematoxylin-eosin staining. The inflammatory cytokines were examined by enzyme-linked immunosorbent assay (ELISA). The key apoptosis proteins and autophagy-relevant proteins were analyzed by western blotting. In vitro, HPMEC models of ALI were treated with LPS. The inflammatory cytokines were detected. Apoptosis rate was determined by flow cytometry. The autophagy and mTOR/TFEB signaling pathway-related proteins were detected by western blot and immunohistochemical staining. Results. HRS attenuated LPS-induced ALI and apoptosis both in vivo and in vitro. HRS attenuated inflammatory response, inhibited apoptosis, induced and activated autophagy in LPS-induced ALI model, and downregulated mTOR/TFEB signaling pathway. The protection of HRS can be blocked by autophagy inhibitor. Moreover, mTOR activator reversed HRS protection and mTOR inhibitor enhanced HRS protection in LPS-induced model and HRS activated autophagy via mTOR/TFEB signaling pathway. Conclusion. The results confirmed the protection of HRS in LPS-induced ALI by regulating apoptosis through inhibiting the mTOR/TFEB signaling pathway.

Molecular hydrogen exerts biological effects on nearly all organs. It has anti-oxidative, anti-inflammatory, and anti-aging effects and contributes to the regulation of autophagy and cell death. As the primary organ for gas exchange, the lungs are constantly exposed to various harmful environmental irritants. Short- or long-term exposure to these harmful substances often results in lung injury, causing respiratory and lung diseases. Acute and chronic respiratory diseases have high rates of morbidity and mortality and have become a major public health concern worldwide. For example, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. An increasing number of studies have revealed that hydrogen may protect the lungs from diverse diseases, including acute lung injury, chronic obstructive pulmonary disease, asthma, lung cancer, pulmonary arterial hypertension, and pulmonary fibrosis. In this review, we highlight the multiple functions of hydrogen and the mechanisms underlying its protective effects in various lung diseases, with a focus on its roles in disease pathogenesis and clinical significance.

Acute lung injury (ALI) and acute respiratory distress syndrome, which is a more severe form of ALI, are life-threatening clinical syndromes observed in critically ill patients. Treatment methods to alleviate the pathogenesis of ALI have improved to a great extent at present. Although the efficacy of these therapies is limited, their relevance has increased remarkably with the ongoing pandemic caused by the novel coronavirus disease 2019 (COVID-19), which causes severe respiratory distress syndrome. Several studies have demonstrated the preventive and therapeutic effects of molecular hydrogen in the various diseases. The biological effects of molecular hydrogen mainly involve anti-inflammation, antioxidation, and autophagy and cell death modulation. This review focuses on the potential therapeutic effects of molecular hydrogen on ALI and its underlying mechanisms and aims to provide a theoretical basis for the clinical treatment of ALI and COVID-19.

Ageing is a physiological process of progressive decline in the organism function over time. It affects every organ in the body and is a significant risk for chronic diseases. Molecular hydrogen has therapeutic and preventive effects on various organs. It has antioxidative properties as it directly neutralizes hydroxyl radicals and reduces peroxynitrite level. It also activates Nrf2 and HO-1, which regulate many antioxidant enzymes and proteasomes. Through its antioxidative effect, hydrogen maintains genomic stability, mitigates cellular senescence, and takes part in histone modification, telomere maintenance, and proteostasis. In addition, hydrogen may prevent inflammation and regulate the nutrient-sensing mTOR system, autophagy, apoptosis, and mitochondria, which are all factors related to ageing. Hydrogen can also be used for prevention and treatment of various ageing-related diseases, such as neurodegenerative disorders, cardiovascular disease, pulmonary disease, diabetes, and cancer. This paper reviews the basic research and recent application of hydrogen in order to support hydrogen use in medicine for ageing prevention and ageing-related disease therapy.

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