Chemical and Biochemical Aspects of Molecular Hydrogen in Treating Kawasaki Disease and COVID-19.
川崎病およびCOVID-19に対する分子状水素の化学的・生化学的作用に関するレビュー
Abstract
Kawasaki disease (KD) is a systemic vasculitis representing the most prevalent acquired cardiac condition in children across numerous countries, originally identified in Japan. SARS-CoV-2 infection has caused a global pandemic since 2020, and a KD-like condition termed multisystem inflammatory syndrome in children (MIS-C) has emerged in the United States, Italy, France, England, and other European regions, with incidence estimated at roughly 6–10 times or more above historical KD rates. This review examines the chemical and biochemical properties of hydrogen gas relevant to both conditions, focusing on its capacity to reduce oxidative damage, suppress inflammatory cascades, inhibit apoptotic signaling, and attenuate abnormal vascular inflammation. The potential mechanistic basis for hydrogen gas inhalation as an investigational approach in KD and COVID-19 is discussed.
Mechanism
Hydrogen gas selectively scavenges reactive oxygen species, particularly hydroxyl radicals, thereby reducing oxidative stress, dampening inflammatory signaling, inhibiting apoptosis, and suppressing abnormal vascular inflammation implicated in both Kawasaki disease and COVID-19 pathophysiology.
Bibliographic
- Authors
- Chen KD, Lin W, Kuo HC
- Journal
- Chem Res Toxicol
- Year
- 2021 (2021-04-19)
- PMID
- 33719401
- DOI
- 10.1021/acs.chemrestox.0c00456
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
See also: