Polydatin protects against ovalbumin-induced bronchial asthma in rats; involvement of urocortin and surfactant-D expression

Abstract

Context: Prevalence of bronchial asthma massively increases worldwide, while the frequent therapies are still not sufficient. Polydatin, a naturally occurring glycoside, was known as to have anti-inflammatory and anti-oxidant effects.

Objective: The current study aimed to investigate the possible protective effect of polydatin against experimental bronchial asthma in rats.

Material and methods: Bronchial asthma was induced by ovalbumin (OVA) sensitization and challenge. Rats were randomly allocated into five groups; Group I (normal control group); Group II (asthma control group) received OVA; Group III (reference standard treatment group) received dexamethasone (1 mg/kg/day); Group IV (treatment group) received polydatin (200/mg/kg); and Group V (polydatin control group). The inflammatory biomarkers interleukin-4 (IL-4), IL-5, IL-13, tumor necrosis factor-alpha, interferon-gamma and absolute eosinophil count in bronchoalveolar lavage fluid (BALF), as well as serum immunoglobulin E were assessed, coupled with the oxido-nitrative stress biomarkers malondialdehyde and glutathione reduced levels and superoxide dismutase activity in the lung tissue, besides inducible nitric oxide synthase level in BALF. Western blot analysis of surfactant-D and immunohistochemical assay of urocortin (UCN) expression in the lung was performed.

Results: Polydatin significantly reduced the inflammatory mediators and restored the normal values of oxidative and nitrosative stress biomarkers. It also significantly reduced the expression of surfactant-D and UCN as compared to asthma control. The histopathological study strongly augmented the biochemical results.

Discussion and conclusions: Polydatin may be a promising protective agent against experimentally induced bronchial asthma. Modulation of SP-D and UCN expressions seems to mediate such protective effects.

Keywords:

• Bronchial asthma
• urocortin
• surfactant-D
• ovalbumin
• polydatin
• dexamethasone

Acknowledgements

The authors would like to thank Prof. Dr. Lyla Ahmed Rashed, Professor of Biochemistry, Faculty of Medicine, Cairo University, for her assistance in performing biochemical analysis and Prof. Dr Kawkab Abd El-Aziz Ahmed, Professor of Histology, Faculty of Veterinary Medicine, Cairo University, for her kind help in performing histopathological and immunohistochemichal study.

Disclosure statement

No potential conflict of interest was reported by the authors.