Effect and underlying mechanism of thrombospondin-1 knockout on radiation-induced pulmonary fibrosis in mice

Abstract

Objective To investigate the effect of thrombospondin-1(TSP-1) knockout on radiation-induced pulmonary fibrosis and explore its underlying mechanism. Methods Male wild type C57BL/6 mice (6~8 weeks old, WT mice) and TSP-1 knockout mice (TSP-1-/- mice) were subjected and received 16 Gy 60Co γ-ray whole lung irradiation (IR) to induce radiation pulmonary fibrosis, and then, the mice were assigned into WT+IR group and TSP-1-/-+IR group, respectively, with 6 mice in each group.In 16 weeks after irradiation, HE staining was performed to observe the morphological changes in lung tissues, and Sirius red staining was used to observe the collagen expression in lung tissues.qRT-PCR was employed to detect the mRNA expression of TGF-β1 and Collagen Ⅰ in lung tissues.Micro-CT scanning was adopted to evaluate lung injury and substantial lung changes.FlexiVent system was employed to assess pulmonary function.Immunofluorescence staining was conducted to measure the protein levels of LC-3 and p62 in lung tissues.Transmission electron microscopy (TEM) was used to observe the cellular autophagic vesicles in lung tissues. Results Compared with the WT+IR group, the TSP-1-/-+IR group had reduced lung injury and collagen deposition in lung tissue, significantly lower mRNA levels of TGF-β1 and Collagen Ⅰ in lung tissue (P < 0.01), and improved pulmonary function.Immunofluorescence assay and TEM showed that autophagy was observed in the mice of TSP-1-/-+IR group. Conclusion TSP-1 knockout can alleviate radiation-induced pulmonary fibrosis, which may be related to activation of autophagy.

Keywords

• thrombospondin-1
• radiation-induced pulmonary fibrosis
• autophagy
• tgf-β1
• flexivent