Gene Transfer Therapy for Alport Syndrome

描述（由申请人提供）：本提案的长期目标是开发人类Alport综合征的基因转移疗法，这是一种遗传性肾病，目前肾移植是唯一的治疗方法。这种疾病是由IV型胶原蛋白基因突变引起的，IV型胶原蛋白是被称为基底膜的组织结构的组成部分。导致肾功能衰竭的肾小球基底膜（GBM）的恶化是由于GBM中缺乏正常的IV型胶原蛋白而引起的。该建议的中心假设是，GBM的正常IV型胶原组成可以通过将缺陷型胶原的正确拷贝转移到合成GBM蛋白的肾小球细胞中来充分恢复，从而稳定GBM结构并减缓或阻止Alport肾病的进展。在X连锁Alport综合征中，编码IV型胶原α 5链的基因（COL4A5）发生突变。本申请的目的是使用一种实现基因转移到肾小球细胞中的新方法来治疗患有X连锁Aiport综合征（XLAS）的狗。该提案的具体目标是：（1）使用通过开放手术技术递送的用于闭路肾灌注的病毒载体，该病毒载体成功地将编码c_5 IV型胶原的cDNA转移到正常猪的肾小球中以用XLAS治疗狗，（2）构建新的含有全长COL4A5 cDNA的病毒载体，其将能够稳定表达长达一年，（3）开发微创方法，使用经血管导管插入技术进行肾脏闭路灌注，以允许对个体受试者进行重复治疗，以及（4）在犬中进行XLAS基因转移治疗的随机试验。将确定转基因E5（IV）链表达对Alport GBM的分子、结构和功能特性以及对Alport肾病临床病程的影响。在XLAS女性杂合子中表现出的轻度肾病表型表明，即使在男性半合子中实现正常_5（IV）链的嵌合表达，也会产生临床上令人满意的治疗结果。由于犬XLAS是人类Alport综合征的动物模型，因此犬XLAS的成功基因转移治疗将为人类Alport综合征的此类治疗试验提供基础。本研究为其他肾小球疾病的基因转移治疗奠定了基础。

DESCRIPTION (provided by applicant): The long-range goal of this proposal is development of gene transfer therapy for human Alport syndrome, a genetic renal disease for which kidney transplantation currently is the only treatment. The disease results from mutations in genes for type IV collagen, which is an integral component of tissue structures known as basement membranes. Abnormalities leading to renal failure are initiated by deterioration of the glomerular basement membrane (GBM) that occurs because of an absence of normal type IV collagen in the GBM. The central hypothesis of this proposal is that the normal type IV collagen composition of the GBM can be adequately restored by transferring a correct copy of the defective gone into the glomerular cells that synthesize GBM proteins, thus stabilizing GBM structure and slowing or stopping progression of Alport renal disease. In X-linked Alport syndrome, the gene (COL4A5) that encodes the a5 chain of type IV collagen is mutated. The objective of this application is to use a new method of achieving gene transfer into glomerular cells to treat dogs with X-linked Aiport syndrome (XLAS). Specific aims of the proposal are to: (1) use a virus vector delivered by an open surgical technique for closed-circuit renal perfusion that successfully transferred a cDNA encoding c_5type IV collagen into the glomeruli of normal pigs to treat dogs with XLAS, (2) construct new viral vectors containing full-length COL4A5 cDNAs that will enable stable transgene expression for up to one year, (3) develop minimally invasive methods for performing closed circuit perfusion of the kidney using trans-vascular catheterization techniques to permit repeated treatment of individual subjects, and (4) perform randomized trials of gene transfer therapy for XLAS in dogs. Effects of transgenic E5(IV) chain expression on the molecular, structural and functional properties of Alport GBM and on the clinical course of Alport renal disease will be determined. The mild renal disease phenotype manifested in female heterozygotes with XLAS suggests that even achieving mosaic expression of normal _5(IV) chains in male hemizygotes will produce a clinically satisfactory treatment result. Because canine XLAS is an animal model of human Alport syndrome, successful gene transfer therapy for XLAS in dogs will provide a basis for trials of such treatment for Alport syndrome in people. It will also lay the foundation for gene transfer therapy of other glomerular iseases.