Ⅳ型胶原、MMPs和TIMPs在放射性肺损伤重建中的作用

Effect of collagen type Ⅳ, MMPs and TIMPs on remodeling of radiation pulmonary injury

目的探讨Ⅳ型胶原、基质金属蛋白酶（MMPs）及其组织基质金属蛋白酶抑制剂（TIMPs）在放射性肺损伤早期重建中的作用。方法用20研Gy^60Coγ射线照射大鼠右胸部，建立放射性肺损伤模型，1、2、4周后分别取材；用实时荧光定量PCR和免疫组织化学方法，从基因表达和蛋白质合成水平结合图像分析对肺组织Ⅳ型胶原、MMP-2、MMP-9、TIMP-1和TIMP-2 mRNA进行定量分析。结果实时定量PCR基因检测：Ⅳ型胶原表达于1周时升高，2周时下降；MMP-2在2周时达高峰，与Ⅳ型胶原成相反变化趋势；MMP-9呈明显的升高、下降、再升高趋势，与Ⅳ型胶原变化趋势相同；TIMP-1表达较低，各时间点之间无明显差异；TIMP-2呈现略升高、降低、升高趋势，与MMP-2表达相反。免疫组化-图像分析：肺组织Ⅳ型胶原含量于1周即明显增加，2周开始下降；MMP-2在2周时下降，随后升高，后期与Ⅳ型胶原呈相反趋势；MMP-9变化趋势同Ⅳ型胶原，但程度明显高于后者；TIMP-1于2周时轻度升高，与MMP-9趋势相反。结论Ⅳ型胶原、MMP-2和MMP-9及其组织抑制物参与放射性肺损伤早期的无效重建过程，MMP-2和MMP-9具有降解Ⅳ型胶原作用；Ⅳ型胶原降解障碍可能与肺纤维化启动有一定关系。

Objective To explore the effect of collagen type Ⅳ , matrix metalloproteinases （MMPs） and tissue inhibitors of MMPs（TIMPs） on early remodeling after radiation pulmonary injury. Methods Right lungs of rats were irradiated by 6o Co γ-rays at a dose of 20 Gy to induce radiation pulmonary injury, and the lung specimens were taken at weeks 1, 2, 4 after irradiation. Quantitative analysis was performed on pulmonary collagen type Ⅳ, MMP-2, MMP-9, TIMP-2, TIMP-1 at the level of gene expression and protein synthesis using real-time PCR or immunohistochemistry. Results Gene detection using real-time PCR： gene expression of collagen type Ⅳ increased at week 1 and decreased at week 2 after irradiation; MMP-2 reached peak at week 2 in which an opposed alteration trend was displayed; MMP-9 appeared a significant trend of elevation, then decrease and elevation again which was similar to those of collagen type Ⅳ ; expression of TIMP-1 was lower, and there was no marked difference among all time points ; TIMP-2 displayed a trend of slight elevation, then decrease and elevation again, which was opposed to MMP-2. lmmunohistochemistry-image analysis： Pulmonary collagen type IV obviously increased at week 1, and began to decrease at week 2 ; MMP-2 decreased at week 2 and then increased;an opposed alteration trend to that of collagen type IV was displayed; alteration trend of MMP-9 was similar to that of collagen type Ⅳ but the extent was higher; gene expression of TIMP-1 slightly increased at 2 week and an opposed trend to of MMP-9 was displayed. Conclusions Collagen type Ⅳ, MMP-2, MMP-9 and their tissue inhibitors were involved in ineffective remodeling in the early radiation pulmonary injury; MMP-2 and MMP-9 play an important role in degradation of collagen type Ⅳ ; Disturbance of collagen type Ⅳ degradation might have relationship with the initiation of pulmonary fibrosis.