Baicalin Ameliorates Inflammatory Response in a Mouse Model of Rhinosinusitis via Regulating the Treg/Th17 Balance

Objective: Rhinosinusitis is a global health problem affecting millions of people around the world. Baicalin is a bioactive compound isolated from medicinal plant Scutellaria baicalensis Georgi. The present study aims to investigate potential effects of baicalin on clinicopathological changes in nasal/sinus mucosa in a mouse model. Methods: A mouse model of sinonasal inflammation induced by high dose of ovalbumin was applied to evaluate effects of baicalin. Rhinosinusitis symptoms, histopathological features, levels of histamine, immunoglobulin E (IgE), IL-17A, IL-10, and balance of regulatory T cell (Treg)/T-helper 17 (Th17) responses were examined. Results: Baicalin significantly relieved rhinosinusitis symptoms in mice, reduced histopathological changes, and suppressed serum levels of histamine and IgE in a dose-dependent manner. In lymphocytes of mice, baicalin modulated balance of Treg/Th17 proportions by attenuating Th17 cells and enhancing Treg cells, respectively. The serum IL-17A was decreased and IL-10 was increased in mice treated by baicalin. In addition, baicalin promoted levels of Smad protein 3 (p-Smad3) and forkhead box P3 (FOXP3) to promote Treg cells while suppressed levels of p-Stat3 and retineic-acid-receptor-related orphan nuclear receptor gamma t (ROR gamma t) to inhibit Th17 cells. Conclusions: These data demonstrate that baicalin effectively ameliorates sinonasal inflammation in a mouse model by recovering the immunological balance of Treg/Th17 responses. Our finding highlights the potential value of baicalin for the treatment of rhinosinusitis.