# The effects of hydrogen treatment in a cigarette smoke solution-induced chronic obstructive pulmonary disease-like changes in an animal model.
> タバコ煙溶液誘発COPDモデルマウスにおける水素吸入の肺組織学的効果


## Abstract

Using female BALB/c mice with COPD-like lung injury induced by intraperitoneal injection of cigarette smoke solution (CSS) twice weekly for 6 weeks, this study examined the effects of inhaling a 42% hydrogen-oxygen gas mixture for 75 minutes twice daily over 9 weeks. Compared with untreated COPD mice, the hydrogen-exposed group showed a higher survival rate (100% vs 80%) during the induction phase. Histopathological assessment revealed significant improvements in mean linear intercept (MLI) and composite lesion scores encompassing inflammation and emphysema. Neutrophil elastase activity was numerically reduced in hydrogen-treated animals, although the difference did not reach statistical significance. Goblet cell hypertrophy and airway epithelial hyperplasia did not show significant improvement. These findings suggest that hydrogen-oxygen inhalation can partially ameliorate alveolar structural damage and inflammatory pathology in a CSS-based COPD animal model.

### Mechanism

Hydrogen's antioxidant and anti-inflammatory properties are thought to suppress neutrophil elastase activity, thereby reducing alveolar structural destruction and attenuating inflammatory lesion scores in CSS-exposed lung tissue.

## Bibliographic

- **Authors**: Yang H, Tsou WH, Shen M, Liu C, Saunders HM, Wang K, et al.
- **Journal**: J Thorac Dis
- **Year**: 2022
- **PMID**: [36524091](https://pubmed.ncbi.nlm.nih.gov/36524091/)
- **DOI**: [10.21037/jtd-22-324](https://doi.org/10.21037/jtd-22-324)
- **PMC**: [PMC9745525](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9745525/)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 42%

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 36524091. https://h2-papers.org/en/papers/36524091
> **Source**: PubMed PMID [36524091](https://pubmed.ncbi.nlm.nih.gov/36524091/)