Expression of epidermal growth factor receptor and its ligands in chronic asthma mice and the influence of dexamethasone

    CAO Weiª²Jun, LI Qiang, LIU Zhongª²Ling

    Department of Respiratory Disease, Changhai Hospital, Second Military Medical University, Shanghai 200433, China

    ¡¾Abstract¡¿ AIM: To investigate the effect of epidermal growth factor receptor (EGFR) system on the asthmatic airway remodeling.METHODS: The chronic asthma mice model was established by ovalbumin (OVA) immunization. Mice were injected intraperitoneally with dexamethasone of 2 mg/kg 1 h before the sensitization and sacrificed by cervical dislocation 24 h after the last challenge. Conventional pathological slides were also observed to study the pulmonary inflammation and the thickness of airway wall and airway smooth muscles. The concentration of TGFª²¦Á in bronchoalveolar lavage fluid (BALF) was detected by ELISA. RTª²PCR was conducted to detect the mRNA expression of EGFR in the lungs. Pulmonary EGFR protein was observed by immunohistochemical staining and Western blot analysis. RESULTS: In chronic asthma mice, inflammatory cell infiltration around bronchi and vessels could been seen on slides. The airway wall and the airway smooth muscles thickened and TGFª²¦Á in BALF increased. The expression of EGFR mRNA and protein in the lungs increased (P<0.01). Dexamethasone injection before sensitization decreased TGFª²¦Á in BALF and the expression of phosphoª²EGF receptor protein in the lung alleviated the pulmonary inflammation and inhibited the thickening of airway wall and airway smooth muscle (P<0.01). CONCLUSION: Airway remodeling occurs in the chronic mice asthma model. Early dexamethasone injection can inhibit the expression and activation of EGFR system, decrease the TGFª²¦Á concentration in BALF and prevent the airway remodeling. ......