Attenuation of pulmonary damage in aged lipopolysaccharide-induced inflammation mice through continuous 2 % hydrogen gas inhalation: A potential therapeutic strategy for geriatric inflammation and survival.
高齢マウスのLPS誘発炎症モデルにおける2%水素ガス持続吸入による肺障害軽減効果
Abstract
Against the backdrop of rising sepsis incidence in aging populations, this animal study examined the effects of hydrogen gas inhalation on LPS-induced systemic inflammation in 21–23-month-old male mice. Eight experimental groups were established, varying H2 concentration (1% or 2%) and exposure duration (1, 6, or 24 hours). Only the 24-hour 2% H2 inhalation regimen produced significant improvements: survival rates and locomotor activity increased, while mRNA levels of inflammatory markers in lung and liver tissue declined. Lung-specific senescence-associated molecules—including CXCL2, MMP-3, arginase-1, and the cell-cycle inhibitor p21—were also downregulated. Hepatic injury induced by LPS was not meaningfully altered under any tested condition. These findings indicate that prolonged, higher-concentration H2 inhalation selectively modulates pulmonary inflammation and aging-related molecular signatures in elderly mice.
Mechanism
Continuous inhalation of 2% H2 for 24 hours suppressed mRNA expression of inflammatory cytokines and senescence-associated proteins (CXCL2, MMP-3, arginase-1, p21) in lung tissue, thereby reducing LPS-induced pulmonary injury in aged mice.
Bibliographic
- Authors
- Aokage T, Iketani M, Seya M, Meng Y, Ageta K, Naito H, et al.
- Journal
- Exp Gerontol
- Year
- 2023
- PMID
- 37572992
- DOI
- 10.1016/j.exger.2023.112270
Tags
Delivery context
In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.
Safety notes
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