Inhibitory effect of baicalin on allergic response in ovalbumin-induced allergic rhinitis guinea pigs and lipopolysaccharide-stimulated human mast cells.

OBJECTIVE: Baicalin, a flavonoid compound purified from the dry roots of Scutellaria baicalensis Georgi, has generally been used for the treatment of various allergic diseases. However, there is little information about the anti-inflammatory effects of baicalin for allergic rhinitis. This study aims to investigate the anti-allergic effect of baicalin on allergic response in ovalbumin (OVA)-induced allergic rhinitis guinea pigs and lipopolysaccharide (LPS)-stimulated human mast cells. METHODS: Using in vivo models, we evaluated the effect of baicalin on allergic rhinitis symptoms via recording the number of nasal rubs and sneezes. The levels of histamine, OVA-specific immunoglobulin E(IgE), eosinophil cationic protein (ECP) and inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The histological changes of nasal mucosa were observed by light microscope after HE staining. In vitro, the release of histamine and ß-hexosaminidase of compound 48/80-induced human mast cells were measured by ELISA and PNP-NAG colorimetry, respectively. The productions of inflammatory cytokines of LPS-stimulated human mast cells were determined using ELISA. Western blot was used to test the protein expression of JAK2, p-JAK2, STAT5, p-STAT5, IKKß, p-IKKß, IκBα, p-IκBα and NF-κB (p65) of LPS-stimulated human mast cells. RESULTS: The oral administration of baicalin at doses of 50 and 200 mg/kg improved allergic rhinitis symptoms and the histological changes of nasal mucosa and decreased the serum levels of histamine, ECP, interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor (TNF)-α and OVA-specific IgE in OVA-induced allergic rhinitis guinea pigs. In vitro, baicalin suppressed the release of histamine and ß-hexosaminidase in compound 48/80-induced human mast cells. In addition, baicalin also inhibited the productions of inflammatory cytokines such as IL-1ß, IL-6, IL-8 and TNF-α and suppressed the phosphorylation of JAK2, STAT5, IKKß, IκBα and the nuclear translocation of NF-κB (p65) subunit in LPS-stimulated human mast cells. CONCLUSIONS: These results suggest that baicalin can effectively prevent allergic response in OVA-induced allergic rhinitis guinea pigs and inhibit inflammatory response via blocking JAK2-STAT5 and NF-κB signaling pathways in LPS-stimulated human mast cells. Considered together,the results show that baicalin may be a useful drug in the treatment of allergic rhinitis.