Innate inflammatory response to acute inhalation exposure of riot control agent oleoresin capsicum in female rats: An interplay between neutrophil mobilization and inflammatory markers

Abstract

Aim: The use of oleoresin capsicum (OC) sprays, due to their irreversible health effects has now grown into a matter of heated debate. In the present study, the early phase pulmonary events involving chemotactic and inflammatory mediators after short-exposure duration to OC have been presented.

Materials and methods: Female Wistar rats used in the evaluation of respiratory parameters at 1 h, 3 h, and 24 h post-exposure, were sacrificed for the evaluation of blood cell counts, BALF cytokine estimation, lung capillary leakage, study of oxidative stress and histopathology of the lungs.

Results: Results confirmed a dose-dependent effect of OC exposure on serum clinical chemistry and hematological parameters. Subsequent upregulation of IL-l and TNF-α indicated lung’s responses to acute oxidant-induced injury and inflammation after OC exposure. Significant alterations in the pulmonary levels of reactive oxygen intermediates were seen following the inhalation of OC. Infiltration of polymorphonuclear leukocytes, mostly neutrophils, into the site of infection was evident in the cytocentrifuged samples of BALF. Histological samples of rat lung sections revealed the recruitment of inflammatory cells in the airways and around blood vessels in the subepithelium of conducting airways.

Conclusion: Results of the present study demonstrated that, exposure to OC spray may mitigate inflammatory response and development of acute lung injury in rats. However, it can be concluded that although OC spray causes pulmonary hazards in the aforementioned concentrations, it can be used as a non-lethal riot control agent in minimal concentration. Understanding the in-depth mechanism of action in the molecular and receptor level will help in developing effective antagonist against OC.

Keywords:

• Acute lung injury
• neutrophils
• NLRP3 inflammosome inflammasome
• oleoresin capsicum
• riot control agent
• TNF-α

Acknowledgment

One of the authors, Ms. Pompy Patowary, is grateful to Defence Research Laboratory (DRL), Tezpur, Assam, India under Defence Research and Development Organisation (DRDO), Ministry of Defence, Govt. of India, and also to the Department of Pharmaceutical Sciences, Dibrugarh University, Dibrugarh, Assam, India for providing the necessary support in carrying out this review study. The authors are also grateful to Mr. Pulak Bora, Asst. Prof., Kaziranga University, Assam, India, for reviewing the manuscript as a grammatical expert.

Declaration of interest

The authors declare no conflict of interest.

Additional information

Funding

The funding for the study was provided by Defence Research and Development Organisation, Ministry of Defence, India.