OBJECTIVETo investigate the dynamic expression of Heat shock protein 70 (Hsp70) in the lungs and plasma of rats with pulmonary fibrosis induced by silicon dioxide (SiO2).

METHODSForty-eight Wistar rats were randomly divided into the control group exposed to normal solution and group exposed to SiO2 (50 mg/ml) with intratracheal injection. Each group was divided into four subgroups. The animals of SiO2 group and control group were sacrificed and lungs were collected on the 7th, 14th and 28th days after exposure, respectively. The left lung tissues were examined with the histopathologic HE staining. The expression and localization of Hsp70 protein in the lung tissues were examined with western blot assay and immunohistochemistry, respectively. The expression levels of Hsp70 protein in the plasma were measured by ELISA.

RESULTSThe expression of Hsp70 in lung tissues of SiO2 group increased on the 7th day and reached the peak value on the 14th day then decreased, but still was significantly higher than that of the control group, the expression of Hsp70 in plasma of SiO2 group still was significantly higher than that of the control group (P < 0.05). The maximum expression level of Hsp70 in plasma of SiO2 group on the 21st day after exposure was 0.216 ± 0.027 µg/ml.

CONCLUSIONThe expression levels of Hsp70 protein in the lung tissues and plasma of the group exposed to SiO2 significantly increased, which were associated with the process of pulmonary fibrosis. It was suggested that Hsp70 protein may play an important biological role in the pulmonary fibrosis induced by SiO2.