A Study On The Mechanism Of Apoptotic Death Of Mouse Alveolar Type Ⅱ Cells Induced By Anaphylatoxin C5a

The 'epithelial hypothesis' linked apoptotic death of alveolar epithelial cells with the pathogenesis of acute lung injury. It suggested that the epithelial injury caused by apoptotic death of alveolar epithelial cells can trigger sever Inflammatory reaction and in some type of acute lung injury. The important pro-inflammatory factor C5a is prodused when complement system activating. Outcomes of excessive generation of C5a, as occurs in severe infection, when relatively high levels (10–100 nM) of C5a was present in the plasma. Macrophages and endothelial cells produced excessive levels of pro-inflammatory mediators and lead to systemic inflammatory response syndrome and multiple organ dysfunction syndrome. So excessive levels of C5a was an important trigger of ALI. A few of researchers work linked C5a with apoptotic death of some kinds of cells. They found that thymocytes undergone C5a-mediated caspase activation and apoptosis. Anothers reported that C5a delayed apoptosis of human neutrophils. We were intresting at the relationship among C5a ,apoptotic death of cells and ALI . Calpains can activate some apoptotic genes such as Bax gene and lead to apoptosis by promoting the releasing of cytochrome-C from the mitochondrion. On the contrary , a report suggested thatμ-calpain delayed apoptotic death of neutrophil by regulating Bax and subsequent caspase-3 activation. So we supposed that C5a and calpains may have a cooperation on apoptosis. In this study we researched on the apoptotic death of mouse AT-Ⅱcells induced by C5a.Methods:1. Isolation,purification,identification and primary culture of mouse alveolar type II cells: Obtain crude lung cell suspensions by enzymatic digestion. Identificate alveolar typeII cells by electron microscope and alkali phosphatase staining method. 2. Induced apoptotic death of alveolar type II cells by C5a There were there groups : the normal control group, the C5a group and the PD150606 group. After the apoptotic death of AT- II cells was induced, stained cells with FITC/PI and...