The Effect Of IGFBPrP1Mediated By Adenovirus(Ad) On Liver Tissue In Rats

BackgroundInsulin-like growth-factor binding protein-related protein1(IGFBPrP1) was cloned by the American scholar Murphy from normal human mammary epithelial cells and leptomeningeal cells in1993. It is an adhesion glycoprotein which is soluble and is secreted in liver. Activated hepatic stellate cell is the major source cell of IGFBPrP1. IGFBPrP1gene is located on human chromosome4q12, encoding a group of precursor proteins which contain282amino acid residues. The present study showed, IGFBPrP1mainly has two functions:firstly, it has the IGFs-dependent function. IGFBPrP1involves in transporting IGFs in blood vessels, delaying half-life of IGFs, regulating the clearance rate of IGFs and the bingding of IGFs and IGFs receptor. Thus it indirectly and directly regulates the biological activity of IGFs; secondly, IGFBPrP1also has the IGFs-independent function, and it is a typical inhibition of tumor growth factor. Tutor preliminary found that IGFBPrP1can result in liver fibrosis; she injected intraperitoneally recombinant murine IGFBPrP1(rm IGFBPrP1) into C57BL/6wild-type mice, and the ruslts showed that exogenous IGFBPrP1can directly cause liver fibrosis. However, IGFBPrP1injected intraperitoneally into rats administered short half-life, fast metabolism, and drug utilization rate is low; intraperitoneal injection into rats could go through the systemic circulation after mesenteric vein absorption, so the effect is slow and the function of IGFBPrP1can not be really understood. Is there more rapid and more effective method to research the effect of IGFBPrP1on liver tissue in rats? To clarify this problem, we design this issue.ObjectiveTo investigate whether IGFBPrP1mediated by adenovirus can result in hepatic fibrosis.MethodsTwenty-four male SD rats were randomly classified into three groups. They were normal group, negative control group (Ad-GFP group) and Ad-IGFBPrP1group. Each group has eight rats. Nothing was done in normal group. Ad-GFP of2.5×109pfu was injected into coccygeal vein once in Ad-GFP group. Ad-IGFBPrPl of2.5×109 pfu was injected into coccygeal vein once in Ad-IGFBPrP1group. Four weeks later, put rats to death and fix liver tissue with10%neutral formaldehyde. Then liver tissue was stained by HE staining to evaluate pathomorphological changes of the liver tissue; the expressions of alpha-smooth muscle actin(marker protein of HSC activation) and fibronectin in liver tissue were tested by immunohistochemistry(IHC) method.Results(1) The HE staining analysis:Normal group and Ad-GFP group showed intact lobular architecture and hepatocytes in order. But Ad-IGFBPrP1group showed disordered organizational structure of liver, a lot of oedematous hepatocytes, a few pyknotic and shattering hepatocyte nuclear and marked hyperplasia of fibrous connective tissue.(2) The IHC staining analysis:compared with normal group or Ad-GFP group the expressions of alpha-smooth muscle actin and fibronectin in liver tissue of Ad-IGFBPrP1group significantly increased(a-SMA:3.10±0.13vs0.19±0.03,3.10±0.13vs0.19±0.03, F=477.927, P<0.01; Fn:32.00±0.93vs0.37±0.01,32.00±0.93vs0.40±0.01, F=1161.479, p<0.01).ConclusionAd-IGFBPrP1can result in liver fibrogenesis and the mechanism relates to activate HSC to stimulate the synthesis and secretion of fibronectin which is the principal component of ECM.