[Effect of heparin on histone-mediated the expression of von Willebrand factor and fibrinogen in lung tissue].

To observe the effects of histones on lung injury and von Willebrand factor (vWF) and fibrinogen (FIB) levels in mice, and to explore the protective effect of heparin.Twenty-four male C57BL/6 mice aged 6-10 weeks were divided into control group, histone group and histone+heparin group according to random number table method with 8 mice in each group. The mice in the histone group were injected with histone (50 mg/kg) via the tail vein, and the mice in the histone+heparin group were injected with unfractionated heparin (400 U/kg) via the tail vein at 1 hour after administration of histone, and those in the control group were given the same amount of normal saline. Four hours after histone injection, the lungs of the mice were harvested and the lung wet/dry weight ratio (W/D) and the pulmonary water contents were measured. The pathological changes in lung tissue were observed by hematoxylin and eosin (HE) staining under microscope, and the extent of lung injury was evaluated. The positive expression of vWF which was the marker of endothelial cell injury was observed by immunohistochemistry. The real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the expression level of FIB mRNA in lung tissue.

The lung W/D ratio and pulmonary water contents in the histone group were significantly higher than those in the control group [lung W/D ratio: 6.19±0.53 vs. 4.54±0.25, pulmonary water contents: (82.59±2.03)% vs. (78.52±1.51)%, both P < 0.01]. The lung W/D ratio and pulmonary water contents in the histone+heparin group were significantly lower than those in the histone group [lung W/D ratio: 4.84±0.35 vs. 6.19±0.53, pulmonary water contents: (79.21±1.48)% vs. (82.59±2.03)%, both P < 0.01], indicating that the heparin could reduce histone-induced pulmonary edema. Histological examination showed that the alveolar structure of the control group was intact, and the alveolar cavity was clean without exudation. In the histone group, the lungs were significantly damaged. The alveolar wall was thickened, infiltrated by inflammatory cells and focally alveolar hemorrhage, edema, associated with alveolar fibrin deposition and micro-thrombus formation. The lung histopathological score in the histone group was significantly higher than that in the control group (5.15±0.87 vs. 0.18±0.17, P < 0.01). All of the pathological changes were significantly alleviated in the histone+heparin group, and the histopathological score of the lung was significantly lower than that in the histone group (2.28±0.72 vs. 5.15±0.87, P < 0.01), indicating that the histone-induced lung injury was improved by heparin. Immunohistochemistry showed that high vWF expressions of lung tissue were observed in the histone group while there was almost no positive expression in the control group, and the vWF expression in the histone+heparin group was significantly reduced, indicating that heparin protected mice against histone-induced endothelial cell injury. The FIB mRNA expression of lung tissue in the histone group was about 49.82 times of the control group (2^-ΔΔCT: 55.30±18.84 vs. 1.11±0.45, P < 0.01), and the expression of FIB mRNA in the histone+heparin group was decreased, which was 23.87 times of the control group (2^-ΔΔCT: 26.50±9.97 vs. 1.11±0.45, P < 0.01), but it was significantly lower than that in the histone group (2^-ΔΔCT: 26.50±9.97 vs. 55.30±18.84, P < 0.01), indicating that heparin could inhibit histone-induced hypercoagulable environment in lung.

Histone causes pulmonary edema, endothelial cell injury and coagulation activation. Heparin could effectively attenuate histone-induced lung injury and coagulation activation.