OBJECTIVETo study the expression of the epidermal growth factor receptor (EGFR) and the oncogene c-erbB2 on pulmonary fibrosis induced by bleomycin (BLM) in rats.

METHODSFifty-four Wistar rats were randomly divided into three groups, the pulmonary fibrosis group (BLM), Iressa group and the control group. There were 18 rats in each group. Control group were injected with saline 0.2-0.3 ml in trachea. Iressa group and BLM group were injected with BLM intratracheal. After the fibrosis models were build, Iressa group were given orally Iressa (200 mg/kg)1 h before modeling in Iressa group, saline were fed 10 ml/kg in BLM group and control group. The three groups were fed 5 times per week; and were sacrificed after treatment on days 1, 14 and 28 respectively. The lungs were harvested for histological studies.

RESULTSThe lung tissue in Iressa group showed fibrosis and inflammatory cell infiltration, the same as shown in the BLM group. The pulmonary fibrosis score was significantly lower than the BLM group on the 28 th day (2.17 +/- 0.41 vs 3.50 +/- 0.84, P < 0.01). Compared with the control group, c-erbB2 and EGFR were hyper expressed significantly both in BLM group and Iressa group at all time points (P < 0.01); c-erbB2 expression had no changes between the Iressa group and the BLM (P > 0.05), that were gradually decreased, and was significantly different at each time point (P < 0.01). EGFR expression was increased gradually on the 14th and 28th day (0.17 +/- 0.02 and 0.28 +/- 0.04) in Iressa group ,that was significantly lower than the BLM group (0.27 +/- 0.04 and 0.34 +/- 0.02) (P < 0.01). EGFR expression increased significantly on the 28th day than on the 14th day in the Iressa group (P < 0.01).

CONCLUSIONThe expression of C-erbB2 and EGFR are enhanced in different stages of alveolitis and pulmonary fibrosis, c-erbB2 and EGFR may be participated in different stages of pulmonary fibrosis.