Mechanism of Qingfei Oral Liquid Flavonoids in Improving Lung Epithelial Barrier Damage in RSV-Infected Mice

  OBJECTIVE  To investigate the protective mechanism of flavonoids in Qingfei Oral Liquid(Fla) on pulmonary epithelial barrier damage in respiratory syncytial virus (RSV)-infected mice.

  METHODS  BALB/c mice were randomly divided into normal group, model group, low- and high-dose groups of flavonoids in Fla(30, 60 mg·kg^-1·d^-1), positive drug ribavirin group (46 mg·kg^-1·d^-1). RSV-infected mice model was established. After continuous administration for 4 d, the pathological changes of lung tissue were observed by HE staining; ELISA was used to detect the contents of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α); Protein content in BALF and BALF/serum fluorescence ratio were used to evaluate lung epithelial permeability; Western blot was used to detect the protein expression of Claudin-1, Occludin, ZO-1, p38 mitogen-activated protein kinase (p38 MAPK), p-p38 MAPK, TLR4 and Myd88 in lung tissue.

  RESULTS  Compared with the model group, the lung pathological damage in Fla group was alleviated (P < 0.05, P < 0.01), the contents of IL-1β and TNF-α in BALF decreased (P < 0.05, P < 0.01), the protein content in BALF and the ratio of BALF/serum fluorescence decreased (P < 0.05, P < 0.01), the levels of Claudin-1, Occludin and ZO-1 in the lung tissue increased (P < 0.05, P < 0.01), the protein expression of p-p38 MAPK/p38 MAPK, TLR4 and Myd88 decreased (P < 0.05, P < 0.01).

  CONCLUSION  Fla might inhibit the TLR4/MyD88/p38 MAPK pathway, increase the tight junction protein, and reduce lung inflammation, thereby improving the lung epithelial barrier damage caused by RSV.