# Protective effects of hydrogen gas against sepsis-induced acute lung injury via regulation of mitochondrial function and dynamics.
> 敗血症誘発性急性肺傷害に対する水素ガス吸入の保護効果：ミトコンドリア機能および動態の調節を介したメカニズム


## Abstract

Using a cecal ligation and puncture (CLP) mouse model, this study examined the effects of 2% hydrogen gas inhalation on sepsis-induced acute lung injury (ALI) in male ICR mice divided into four groups: sham, sham plus H2, CLP, and CLP plus H2. At 24 hours post-operation, histological examination and transmission electron microscopy were performed. Compared with the CLP-only group, hydrogen gas inhalation significantly elevated the oxygenation index (PaO2/FiO2), mitochondrial membrane potential, ATP levels, respiration control ratio, complex I activity, and mitofusin-2 (MFN2) expression. Concurrently, histological injury scores and dynamin-related protein 1 (Drp1) levels were reduced. These findings indicate that 2% H2 inhalation can restore mitochondrial bioenergetics and shift the fission-fusion balance toward fusion, thereby conferring protection against sepsis-associated pulmonary damage.

### Mechanism

H2 inhalation suppresses Drp1-mediated mitochondrial fission while upregulating MFN2-driven fusion, thereby restoring mitochondrial membrane potential, ATP synthesis, and respiratory complex I activity in septic lung tissue.

## Bibliographic

- **Authors**: Dong A, Wang Y, Li CY, Chen H, Bian Y, Zhang P, et al.
- **Journal**: Int Immunopharmacol
- **Year**: 2018
- **PMID**: [30380511](https://pubmed.ncbi.nlm.nih.gov/30380511/)
- **DOI**: [10.1016/j.intimp.2018.10.012](https://doi.org/10.1016/j.intimp.2018.10.012)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 2%

## 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 30380511. https://h2-papers.org/en/papers/30380511
> **Source**: PubMed PMID [30380511](https://pubmed.ncbi.nlm.nih.gov/30380511/)