H₂ Papers

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Anti-inflammatory properties of molecular hydrogen: investigation on parasite-induced liver inflammation.

分子状水素の抗炎症作用：寄生虫誘発性肝炎症モデルにおける検討

animal study inhalation positive

Abstract

Molecular hydrogen reacts with hydroxyl radicals, which are highly cytotoxic species generated in inflamed tissues. Using a schistosomiasis-associated chronic liver inflammation model in animals, this study examined the effects of hyperbaric hydrogen exposure (0.7 MPa supplemented to normal atmosphere) over a 2-week period. Infected animals showed significant hepatoprotective outcomes, including reduced fibrosis, improved hemodynamics, elevated NOSII and antioxidant enzyme activities, lower lipid peroxide levels, and decreased circulating TNF-alpha concentrations. Notably, helium under identical conditions also conferred partial protection, suggesting that hydroxyl radical scavenging alone does not account for all observed benefits. These results indicate that additional protective mechanisms beyond radical quenching may be involved in hydrogen-mediated anti-inflammatory effects.

Mechanism

Hydrogen scavenges hydroxyl radicals in inflamed tissue and additionally upregulates NOSII activity and antioxidant enzymes while suppressing TNF-alpha. The partial protective effect of helium under identical conditions suggests that radical scavenging is not the sole mechanism involved.

Bibliographic

Authors
Gharib B, Hanna S, Abdallahi OM, Lepidi H, Gardette B, De Reggi M
Journal
C R Acad Sci III
Year
2001
PMID
11510417
DOI
10.1016/s0764-4469(01)01350-6

Tags

Disease:liver disease (56) Delivery:inhalation delivery (196) Mechanism:antioxidant enzymes (423) hydroxyl radical scavenging (352) anti-inflammatory (743) lipid peroxidation (238) oxidative stress (899) reactive oxygen species (774)

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.

→ Evidence by delivery route

Safety notes

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.

See also:

Other papers on the same disease / condition