Pneumoprotective effect of acetylcysteine during long-term exposure to nitrogen dioxide (experimental study)

Introduction. Nitrogen dioxide is one of the most common anthropogenic air pollutants that initiates oxidative stress and an inflammatory response. In recent years, there has been increased interest in the use of acetylcysteine as a means of preventing and treating conditions accompanied by oxidative stress.

Material and methods. The aim of the study was to evaluate the protective effect of oral administration of acetylcysteine ​​on the in rats exposed to long-term inhalation nitrogen dioxide. The protective effect of oral administration of acetylcysteine on the immunological profile and cellular composition of bronchoalveolar lavage fluid in rats during prolonged inhalation exposure to nitrogen dioxide was evaluated. Exposures to nitrogen dioxide (30–40 mg/m³) were carried out for 60 days (three times a day for 30 minutes with a half-hour interval between them). Every day, half an hour before exposure to nitrogen dioxide, the experimental group was administered a solution of acetylcysteine (50 mg/kg) through an esophageal tube, and the control group was administered a 0.9% sodium chloride solution. The cellular composition of bronchoalveolar lavage fluid, the content of pro-inflammatory mediators (TNF-α, IL-8), neutrophil elastase (NE), matrix metalloproteinase-12 (MMP-12), secretory immunoglobulin A (sIgA) and surfactant protein D (SP-D) were determined.

Results. Under the influence of 60-day exposure to nitrogen dioxide, the cytoimmunological profile of the bronchoalveolar space changed. The influx of neutrophils increased. The content of pro-inflammatory cytokines (TNF-α, IL-8) and proteases with destructive activity (NE, MMP-12) increased. The content of local immune defense markers (SP-D, sIgA) decreased due to a violation of the structural integrity of the bronchoalveolar epithelium. Daily oral administration of acetylcysteine for 60 days of nitrogen dioxide exposure contributed to the preservation of the basic structural and functional status of the lungs, which prevented the development of the inflammatory process and aberrant remodeling of lung tissue.

Limitations. the parameters of bronchoalveolar lavage fluid of animals were analyzed after exposure to nitrogen dioxide (30–40 mg/m³) for 60 days (three times a day for 30 minutes with a half-hour interval between them): the data obtained may differ under different experimental conditions.

Conclusion. The results show that acetylcysteine can serve as an effective prophylactic agent, preventing the negative consequences associated with lung exposure to the oxidative pollutant nitrogen dioxide.

Compliance with ethical standards. The experimental study was approved by the Independent Ethics Committee at the Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation (Protocol No. 273, December 20, 2022), conducted according to the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes (ETS No. 123), European Union Directive 2010/63 EU of 22.09.2010 on the protection of animals used for scientific purposes.

Authors contribution:
Preobrazhenskaya T.N. – conducting the experiment, data analysis, study design, article writing;
Lebedeva E.S. – conducting the experiment, data analysis, article writing.
All co-authors made significant contributions to the conception, conduct of the study and preparation of the article, and read and approved the final version before publication.

Conflict of interest. The authors declare that there are no conflicts of interest related to the publication of this article.

Funding. The study had no sponsorship.

Received: May 12, 2025 / Revised: March 04, 2026 / Accepted: March 27, 2026 / Published: April 30, 2026

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