[Effects of cyanate on pulmonary epithelial cells and pulmonary function in mice].

Objective: To investigate the injury of cyanate on the pulmonary function and morphology of C57/BL6N mice.

Methods: Forty male C57/BL6N mice were randomly divided into two groups: normal control group (20 mice) and cyanate group (20 mice). Mice were exposed to 100 mmol/L cyanate feeding for 4 weeks, and pulmonary Raw (Resistance in Air Way) was measured at the beginning and end of the experiment. The mice were sacrificed at the end of the fourth week of the experiment, and the lung tissues were collected for pathological observation and molecular detection of E-Cadherin and Fibronectin. Well-growing A549 cells in logarithmic growth phase were treated with cyanate at the concentrations of 0, 0.25, 0.5 and 1 mmol/L for 24 h, and the cell viability was detected by CCK8 method; reactive oxygen species ROS fluorescent probe (DCFH-DA) was used to detect the changes of ROS levels, and expressions of E-Cadherin and Fibronectin in cells and pulmonary tissues were detected by Western blot.

Results: At the beginning of the experiment, the pulmonary airway resistance values of the mice in the normal control group and the cyanate group were (1.82±0.76)cmH₂O/(L·s) and (1.85±0.78)cmH₂O/(L·s), respectively, with no significant difference. Four weeks later, the pulmonary airway resistance value of mice in the cyanate group was increased to (4.86±0.87)cmH₂O/(L·s) (P＜0.01). The HE staining showed that, compared with the normal control group, the injured alveolar structure, the thickened tracheal wall and the significantly proliferated pulmonary interstitial tissue were observed in the cyanate group. The Masson staining showed that elastic fibers were deposited around the trachea of mice in the cyanate group. The results of CCK8 assay for the viability of A549 cells showed that 0.5 mmol/L cyanate exposure could reduce the viability (P＜0.01). The immunofluorescence staining showed that cyanate could increase ROS level in A549 cells by producing green fluorescence in a concentration-dependent manner. The results of Western blotting showed that 0.5 mmol/L of cyanate treatment on A549 cells could reduce the expression of E-Cadherin (P＜0.01) with increasing concentration of cyanate. The expression level of Fibronectin in A549 cells was increased with the increasing cyanate concentration, and there was a significant difference (P＜0.01) on 1 mmol/L cyanate. Western blot results of lung showed the decreasing expression of E-Cadherin (P＜0.01) and increasing expression of Fibronectin (P＜0.01) in cyanate mice.

Conclusion: Pathological concentrations of cyanate can induce the proliferation of pulmonary interstitial tissue, fibrous deposition, and increased pulmonary airway resistance in mice, which may be related to damaged pulmonary epithelial cell viability, enhanced ROS production, and induced pathologic changes of extracellular matrix by cyanate.