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Effects of Post-Treatment Hydrogen Gas Inhalation on Uveitis Induced by Endotoxin in Rats.

エンドトキシン誘発ブドウ膜炎ラットモデルにおける水素ガス吸入の後処置効果

animal study inhalation mixed 67%

Abstract

This animal study examined whether post-treatment inhalation of a 67% H2 / 33% O2 gas mixture could reduce ocular inflammation in Sprague-Dawley rats with lipopolysaccharide-induced uveitis. Compared with a nitrogen-oxygen control group, H2-inhaling rats showed no significant improvement in clinical uveitis scores, dark-adapted electroretinography b-wave peak latency, or the number of infiltrating cells in the iris and ciliary body. However, aqueous humor protein concentration was significantly lower in the H2 group (P<0.05), and Iba1 immunostaining revealed a partial reduction in microglial activation. The findings indicate that H2 inhalation after disease induction exerts selective, rather than comprehensive, anti-inflammatory effects in this endotoxin-driven ocular model.

Mechanism

H2 inhalation reduced aqueous humor protein leakage and partially suppressed Iba1-positive microglial activation in the iris and ciliary body, without significantly affecting leukocyte infiltration or overall clinical uveitis severity.

Bibliographic

Authors
Yan W, Chen TX, Long P, Liu Q, Wang X, An J, et al.
Journal
Med Sci Monit
Year
2018 (2018-06-07)
PMID
29875353
DOI
10.12659/MSM.907269
PMC
PMC6020745

Tags

Disease:retinal disease (27) Delivery:inhalation delivery (196) Mechanism:immune modulation (180) anti-inflammatory (743) 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:

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