Development of Gene Therapy for Progrssive Glomerular Diseases

多种生长因子在进展性肾脏疾病的病理生理过程中的作用已被多条证据所证实。在实验性和人肾小球肾炎的肾小球和肾小管间质病变中，观察到转化生长因子-β(TGF-β)和血小板衍生生长因子(PDGF)及其受体的上调。在实验动物中，通过将转化生长因子-β基因导入肾脏或携带转化生长因子-β基因的转基因小鼠而产生过量的转化生长因子-β会导致肾小球硬化。这些证据支持生长因子的关键作用，促使我们利用基因技术干预肾小球硬化的发生发展。为了抑制转化生长因子-β或血小板衍生生长因子的作用，我们构建了受体-免疫球蛋白Fc嵌合体胞外区的表达载体。从培养的COS细胞中获得的纯化的转化生长因子-β-Fc可抑制转化生长因子-β对细胞生长和细胞外基质合成的抑制作用。我们用脂质体的方法将TGFbeta-R-Fc表达载体导入抗Thy-1肾小球肾炎大鼠的臀肌。合成的转化生长因子-β-Fc通过体循环蓄积到肾脏。结果，肾小球转化生长因子-β核糖核酸受到抑制，细胞外基质积聚减少。同样，纯化的β-PDGFR-Fc可抑制PDGF-B诱导的细胞增殖。将β-PDGFR-Fc导入骨骼肌，可抑制肾小球增殖细胞核抗原表达和肾小球细胞数，与减少细胞外基质积聚的作用相当。提示生长因子受体-Fc嵌合体对肾小球硬化的分子干预可能是可行的。

Action of various growth factors in pathophysiological condition in the process of progressive renal diseases has been demonstrated by several lines of evidences. The up-regulation of transforming growth factor-beta (TGF-beta) and Platelet-derived growth factor (PDGF) as well as their receptors are observed in glomerular and tubulointerstitial lesions in experimental and human glomerulonephritis. In experimental animals, overproduction of TGF-beta by gene transfection to kidney or transgenic mouse carrying TGF-beta gene causes glomerulosclerosis. These evidences which support the pivotal role of growth factor prompt us to intervene the development of glomerulosclerosis by gene technology. To inhibit the action of TGF-beta or PDGF we created the expression plasmids for extracellular domain of receptor-immunoglobulin Fc chimera. The purified TGF-betaR-Fc, which was obtained from cultured COS cells, inhibited the suppression of cell growth and extracellular matrix synthesis by TGF-beta. We transfected the expression vector for TGFbeta-R-Fc to the gluteal muscle of the anti-Thy 1 glomerulonephritis by HVJ-liposome method. The synthesized TGF-betaR-Fc accumulated to the kidney through the systemic circulation. Consequently, the glomerular TGF-betamRNA were suppressed and the extracellular matrix accumulation was concomitantly reduced. Similarly, The purified betaPDGFR-Fc inhibited cell proliferation induced by PDGF-B.Transfected betaPDGF-Fc into skeletal muscle suppressed PCNA expression and the cell number of glomerulus in comparable with reduction of ECM accumulation. These results suggest that the molecular intervention by growth factor receptor-Fc chimera may be feasible for the therapy of glomerulosclerosis.