[To explore the therapeutic effect of myrtle oil, anthocyanin and hyaluronic acid in combination with topical application on allergic rhinitis in rats exposed to PM2.5].

Objective:To observe the therapeutic effect of local combination（LC） of myrtle oil, anthocyanin and hyaluronic acid on allergic rhinitis in rats exposed to PM2.5 and explore its mechanism. Method:The rats were randomly divided into 5 groups: normal group, LC group, AR group, AR+PM2.5group and AR+PM2.5+LC. After successful establishment of the model, AR+PM2.5 group and AR+PM2.5+ LC group were intranasally dripped with PM2.5 suspension, while LC group and AR+PM2.5+ LC group were intranasally dripped with LC. The AR symptom score was observed. The eosinophil infiltration in nasal mucosa was observed by hematoxylin-eosin staining. The ultrastructural changes were observed by transmission electron microscope, the level of immunoglobulin IgE, IL-6, IL-8 and TNF-α in serum was detected by enzyme-linked immunosorbent assay, the expression of NF-κBp65 and phosphorylated p38MAPK in nasal mucosa was detected by immunohistochemical staining. Result:There were no significant differences in symptoms, eosinophil infiltration and tissue ultrastructure between normal group and LC group（P>0.05）, but the symptom score, nasal mucosal eosinophil infiltration and serum IgE level in AR group and AR+PM2.5 group were significantly higher than those in normal group（P<0.05）, especially in AR+PM2.5 group（P<0.05）. Compared with AR group and AR+PM2.5 group, the symptom score, eosinophil infiltration and IgE level in AR+PM2.5+LC group were significantly decreased（P<0.05）, and the ultrastructural damage was also significantly improved. Compared with normal group, NF-κBp65, phosphorylated p38MAPK and serum inflammatory factors in AR group and AR+PM2.5 group were increased（P<0.05）, and those in AR+PM2.5 group were higher than those in AR group（P<0.05）. Compared with AR group and AR+PM2.5 group, the expression of inflammatory factors and NF-κBp65 and phosphorylated p38MAPK in nasal mucosa in AR+PM2.5+LC group decreased significantly（P<0.05）. Conclusion:LC has good safety in the treatment of nasal drip and has a significant therapeutic effect on allergic rhinitis rats exposed to PM2.5, which may alleviate the effect of PM2.5 on allergic rhinitis rats by regulating excessive activation of NF-κB and MAPK pathway and reducing eosinophil infiltration and IgE production.