AQP5、MMP-9在重症急性胰腺炎肺损伤中的变化及意义

Changes and significances of AQP5 and MMP-9 in severe acute pancreatitis-associated lung injury

目的:观察重症急性胰腺炎(Severe acute pancreatitis,SAP)肺损伤、肺水肿与水通道蛋白5(Aquaporin 5,AQP5)及基质金属蛋白酶-9(Matrix metalloproteinases-9,MMP-9)表达变化的关系,研究AQP5及MMP-9在SAP肺损伤中的意义。方法:逆行注射5%牛磺胆酸钠制作大鼠SAP模型。40只SD大鼠随机分成实验组(SAP组)和假手术(Shamed-operated,SO)组,分别于3、6、12、24 h观察肺组织病理改变。通过免疫荧光组化、实时荧光定量PCR及Western blot法分析肺组织AQP5及MMP-9的变化。结果:与SO组相比,SAP组肺组织损害明显。通过免疫荧光组化、实时荧光定量PCR和Western blot检测发现,SAP组肺组织AQP5表达在3 h前无明显变化(P>0.05),但6 h后表达明显减少(P<0.05);MMP-9 mRNA的表达水平3 h开始即明显升高,12 h时达峰值,24 h后开始下降(P<0.05);MMP-9蛋白表达从3 h开始呈逐渐增加趋势(P<0.001)。结论:SAP急性肺损伤(Acute lung injury,ALI)早期肺组织AQP5无明显改变,后期则逐渐下降,提示肺AQP5可能不是导致SAP肺损伤早期肺水肿的直接原因;MMP-9大量表达,肺毛细血管基膜溶解,连续性中断,通透性增高是肺损伤早期肺水肿的主要机制;但AQP5表达水平下调影响了AQP5介导的水分子跨膜转运效率,导致肺泡内液清除障碍,促进了肺水肿形成,加重了肺损伤、肺水肿的程度,推进了急性呼吸窘迫综合征(Acute respiratory distress syndrome,ARDS)的进程。

Objective：To observe the changes and significances of aquaporin 5（AQP5）and matrix metalloproteinases-9（MMP-9）in severe acute pancreatitis（SAP）associated with lung injury.Methods：SAP model was prepared through retrograde injection of 5% taurocholic acid.SD rats were randomly divided into SAP group and shamed-operated（SO）group.Lung structure damage and AQP5,MMP-9 expressions in lung tissues were examined at 3,6,12 h and 24 h during disease development through the immunofluorescence staining,real-time PCR and Western blot analysis.Results：Lung tissues were significantly damaged in SAP group compared with those in SO group.Immunofluorescence staining,real-time PCR and Western blot showed that in SAP group,there was no change in AQP5 expression until 3 h（P 0.05）and it was gradually decreased at 6 h afterwards（P0.05）;in SAP group,MMP-9 mRNA expression was significantly increased at 3 h afterwards and was reached the peak at 12 h（P0.05）but was gradually decreased at 24 h afterwards.MMP-9 protein expression was gradually increased at 3 h afterwards（P0.001）.Conclusions：AQP5 expression remains constant in lung tissue at early stage of SAP associated with lung injury,but decreases at later stage.This indicates that AQP5 may not be the direct reason for early edema of lung injury.Large expression of MMP-9,pulmonary capillaries basement membrane dissolution,discontinuity and increase of blood capillary permeability are perhaps the main mechanisms of early edema of lung injury.But the decreased lung AQP5 expression can affect the efficiency of transmembrane transport of water molecule mediated by AQP5,induce alveoli liquid removing obstacles and promote the formulation of lung endema,which will increase the severity of lung edema and propel the process of acute respiratory distress syndrome.