Dynamic changes of surfactant protein-D and Clara cell protein expressions in lung tissue and bronchoalveolar lavage fluid of silica-treated rats

Abstract

To investigate the dynamic changes of surfactant protein-D (SP-D) and Clara cell protein (CC16) expressions in lung tissue and bronchoalveolar lavage fluid (BALF) of silica-treated rats. 80 rats were randomly divided into the control group and the silica group. The silicotic animal model was established by direct tracheal instillation of silica suspension into rat lungs surgically. On 7, 14, 21, 28 and 60 d after establishment of the animal model, eight rats in each group were sacrificed and lung tissue and BALF were collected. Lung tissue chip microarray was made in different time points after the silica was injected. Expressions of SP-D and CC16 on tissue microarray were detected with immunohistochemistry and quantified by Image-Pro Plus Version 4.5 for Windows(TM); The SP-D and CC16 levels of BALF were detected with western blot and quantified by Quantity One Version 4.6.2. SP-D expressed very little in alveolar type II and Clara cell intracytoplasmic of control group while its expression significantly increased after 7 d in silica group (P < 0.01) and it reached the peak on the 14 d, after this SP-D expression decreased gradually. CC16 was expressed strongly in intracytoplasmic and it expressed little in nucleus of Clara cell by bronchioles of control while it significantly decreased after 7 d in silica group (P < 0.01), and CC16 expression decreased gradually with the exposed silica time, which was correlated negatively among them (r(s) = -0.967, P < 0.01). On 7 d and 28 d, the SP-D levels of BALF in silica group were significantly higher than control (P < 0.01). Furthermore the SP-D levels of BALF on 28 d was significantly elevated than that on 7 d in silica group (P < 0.01). On 7 d and 28 d, the CC16 levels of BALF in silica group were significantly lower than control (P < 0.01). Moreover, CC16 levels of BALF on 28 d was significantly decreased than that on 7 d in silica group (P < 0.01). The dynamic changes of SP-D and CC16 protein expressed in lung tissue and bronchoalveolar lavage fluid could be induced by silica exposure and are related with the silica exposure time.