Role of epidermal growth factor in repair of lung tissues in mice with acute respiratory distress syndrome / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of epidermal growth factor (EGF) in repair of lung tissues in mice with acute respiratory distress syndrome (ARDS).Methods:Fifty SPF male C57BL/6 mice, aged 6-8 weeks, weighing 21-23 g, were divided into 5 groups ( n=10 each) using a random number table method: control group (group C), EGF group, LPS+ PBS group, LPS+ EGF group and AG1478+ LPS+ EGF group.PBS 0.1 ml was intraperitoneally injected in group C. EGF 10 μg (0.1 ml) was intraperitoneally injected in group EGF.The equal volume of PBS and EGF 10 μg was intraperitoneally injected at 12 h after tracheal infusion of LPS in group LPS+ PBS and group LPS+ EGF, respectively.EGF receptor (EGFR) antagonist AG1478 1 mg was intraperitoneally injected, 30 min later LPS was tracheally instilled, and 12 h later EGF 10 μg was intraperitoneally injected in group AG1478+ LPS+ EGF.ARDS model was developed by endotracheal instillation of LPS 3 mg/kg.The mice were sacrificed on the 1st and 5th days after development of the model, and lung tissues were obtained for microscopic examination of the pathological changes which were scored after HE staining.Bronchoalveolar lavage was performed on 5th day after development of the model and before sacrifice, and bronchoalveolar lavage fluid (BALF) was collected to detect total protein concentration (by BCA method) and IL-6 and TNF-α concentrations (by enzyme-linked immunosorbent assay). Lung tissues were obtained for determination of the wet/dry lung weight ratio (W/D ratio), expression of lung surfactant associated protein C (SP-C) and proliferating nuclear antigen (PCNA) (by immunofluorescence method), and expression of EGFR, phosphorylated EGFR (p-EGFR), protein kinase B (Akt), and phosphorylated Akt (p-Akt) (by Western blot). Results:Compared with group C, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly increased, the number of cells co-expressing SP-C and PCNA was increased, and p-EGFR/EGFR and p-Akt/Akt ratios were increased in group LPS+ PBS ( P<0.01), and no significant change was found in the indexes mentioned above in group EGF ( P>0.05). Compared with group LPS+ PBS, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly decreased, the number of cells co-expressing SP-C and PCNA was increased, and p-EGFR/EGFR and p-Akt/Akt ratios were increased in group LPS+ EGF ( P<0.01). Compared with group LPS+ EGF, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly increased, the number of cells co-expressing SP-C and PCNA was decreased, and p-EGFR/EGFR and p-Akt/Akt ratios were decreased in group AG1478+ LPS+ EGF ( P<0.01). Conclusions:EGF can promote the repair of lung tissues in mice with ARDS, and the mechanism may be related to activation of EGFR signaling pathway and promotion of proliferation of alveolar epithelial cell type Ⅱ.