Immunoregulatory effects of Glycyrrhizic acid exerts anti-asthmatic effects via modulation of Th1/Th2 cytokines and enhancement of CD4+CD25+Foxp3+ regulatory T cells in ovalbumin-sensitized mice

Ethnopharmacological relevanceGlycyrrhizic acid (GA) is the main bioactive ingredient of licorice (Glycyrrhiza glabra), and has been found to be associated with multiple therapeutic properties.Aim of the studyIn this study, we investigated immunoregulatory effects of glycyrrhizic acid on anti-asthmatic effects and underlying mechanisms.Materials and methodsAsthma model was established by ovalbumin-induced. A total of 60 mice were randomly assigned to six experimental groups: control, model, dexamethasone (2 mg/kg) and GA (10 mg/kg, 20 mg/kg, 40 mg/kg). Airway resistance (Raw) were measured by the forced oscillation technique, histological studies were evaluated by The hematoxylin and eosin (HE) staining, Th1/Th2 and Th17 cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA), and CD4+CD25+Foxp3+ regulatory T cells (Tregs) was evaluated by Flow Cytometry (FCM), the forkhead/winged helix transcription factor (Foxp3) was evaluated by western blotting.ResultsOur study demonstrated that, compared with model group, GA inhibited OVA-induced increases in Raw and eosinophil count; interleukin (IL)-4, IL-5, IL-13 levels were recovered in bronchoalveolar lavage fluid compared; increased IFN-γ level in bronchoalveolar lavage fluid; histological studies demonstrated that GA substantially inhibited OVA-induced eosinophilia in lung tissue and airway tissue compared with model group. Flow cytometry studies demonstrated that GA substantially enhanced Tregs compared with model group.ConclusionThese findings suggest that GA may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

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