Development of Gene Therapy for Progrssive Glomerular Diseases

各种生长因子在进行性肾脏疾病过程中的病理生理状态下的作用已被多条证据所证实。在实验性和人类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，通过基因转染到肾脏或携带TGF-β基因的转基因小鼠中，TGF-β的过量产生导致肾小球硬化。这些证据支持生长因子的关键作用，促使我们通过基因技术干预肾小球硬化的发展。为了抑制TGF-β或PDGF的作用，我们创建了受体-免疫球蛋白Fc嵌合体的胞外结构域的表达质粒。从培养的COS细胞获得的纯化的TGF-β R-Fc抑制TGF-β对细胞生长和细胞外基质合成的抑制。我们用HVJ-脂质体法将TGF β-R-Fc表达载体转染到抗Thy 1肾小球肾炎的臀肌中。合成的TGF-β R-Fc通过体循环累积到肾脏。因此，肾小球TGF-β RNA被抑制，细胞外基质积累也随之减少。同样，纯化的β PDGFR-Fc抑制PDGF-B诱导的细胞增殖。将β PDGF-Fc转染到骨骼肌中抑制PCNA表达和肾小球细胞数量，与ECM积累的减少相当。这些结果表明，生长因子受体-Fc嵌合体的分子干预可能是可行的肾小球硬化症的治疗。

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.