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Effects of Inhalation of Hydrogen Gas on Allergic Conjunctivitis Model Mice.

水素ガス吸入がアレルギー性結膜炎モデルマウスに与える影響

animal study inhalation positive

Abstract

Using an ovalbumin-sensitized mouse model of allergic conjunctivitis, this study examined whether inhaled hydrogen gas could modify allergic ocular responses. Mice received intraperitoneal ovalbumin sensitization followed by daily ocular instillation of the antigen. After antigen challenge, animals in the hydrogen group were exposed to hydrogen gas. Two primary outcomes were assessed: eye-scratching frequency as a surrogate for ocular pruritus, and eosinophil counts in tear fluid. Hydrogen gas exposure significantly reduced antigen-induced scratching behavior and attenuated the rise in tear eosinophil numbers. The authors propose that reactive oxygen species play a central role in both pruritic signaling and eosinophil recruitment, and that hydrogen gas scavenges these species to suppress allergic conjunctival inflammation.

Mechanism

Hydrogen gas is proposed to scavenge reactive oxygen species, thereby suppressing pruritic signaling pathways and reducing eosinophil migration into conjunctival tissue.

Bibliographic

Authors
Sakata H, Kanzaki S, Kai H, Morii H, Haraoka N, Takayama S, et al.
Journal
J Ocul Pharmacol Ther
Year
2026
PMID
42101321
DOI
10.1177/10807683261415800

Tags

Disease:retinal disease (27) Delivery:inhalation delivery (196) Mechanism:hydroxyl radical scavenging (352) 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:

Other papers on the same disease / condition