Rosmarinic acid affects immunological and inflammatory mediator levels and restores lung pathological features in asthmatic rats.

BACKGROUND: The effects of rosmarinic acid (RA) on immunological and inflammatory mediator levels in bronchoalveolar lavage fluid (BALF) as well as lung pathological changes in asthmatic rats were investigated. METHODS: The levels of IFN-γ, IL-4, IFN-γ/IL-4 ratio, IgE, PLA2, and total protein (TP) in BALF and pathological changes in the lung were evaluated in control group (C), asthma group (sensitized to ovalbumin) (A), asthma groups treated with RA and dexamethasone. RESULTS: Compared to the control group, asthmatic rats showed increased levels of IL-4, IgE, PLA2, and TP as well as all pathological scores with decreased levels of IFN-γ and IFN-γ/IL-4 ratio (P<0.05 to P<0.001). The levels of IL-4, IgE, PLA2, and TP significantly reduced in groups treated with all concentrations of RA compared to asthma group (P<0.001 for all cases). IFN-γ was significantly decreased in groups treated with two lower concentrations of RA but IFN-γ/IL-4 ratio was increased in groups treated with two higher concentrations of RA compared to asthma group (P<0.05 to P<0.001). Treatment with all doses of RA led to significant improvement in pathological scores in asthmatic animals (P<0.05 to P<0.001). Most measured parameters were also significantly improved in dexamethasone-treated animals (P<0.01 to P<0.001) but IFN-γ/IL-4 ratio and the scores of interstitial fibrosis, bleeding and epithelial damage did not change in this group. CONCLUSION: The results indicated a preventive effect for RA on immunological and inflammatory mediators as well as lung pathological changes in asthmatic rats which were comparable or even more potent than that of dexamethasone.