Pathogenic Mechanisms Underlying Diabetic Retinopathy

描述（由申请人提供）：引起糖尿病微血管病变性视网膜病变和其他血管并发症的致病过程尚不清楚。一些新的证据表明，炎症起着迄今为止未被认识到的作用。视网膜细胞、脉管系统和其他自身细胞通过一组内在的膜调节蛋白来保护自身补体蛋白免受攻击。这些调节因子是衰变加速因子（DAF或CD55），膜辅助因子蛋白（MCP或CD46）和反应性裂解膜抑制剂（CD59）。我们实验室之前的研究表明，这三种表面蛋白在视网膜及其相关脉管系统中的高表达水平与肾小球细胞和全身脉管系统的表达水平相似，这些地方的内在调节活性至关重要。在最近的体外研究中，我们发现DAF的调节功能1)与葡萄糖或核糖孵育使其失活90%，2)甲基乙二醛孵育使其迅速丧失，3)由于一个或多个活性位点赖氨酸和精氨酸残基被修饰而丧失，后者被修饰为乙基嘧啶。在体内工作中，我们已经证明从糖尿病视网膜中分离的内源性DAF蛋白被几种糖加合物修饰，包括阿氏嘧啶。拟开展的研究旨在：1)确定糖尿病状态下高血糖和其他代谢异常诱导的DAF、MCP、（和CD59）化学修饰的功能作用；2)从结构上表征这些修饰对调节因子的类型和位点；3)分析从糖尿病患者视网膜和其他组织中分离的内源性DAF、MCP、（和CD59）蛋白的功能和结构。4)检测Daf1-/-（小鼠DAF同系物）、Crry-/-（小鼠MCP替代物）、CD59a-/-（小鼠CD59同系物）和双Daf1-/- /-或Daf1-/- / CD59a-/-小鼠用链脲霉素诱导的糖尿病小鼠中，与视网膜病变和其他糖尿病并发症相关的病理改变是否发展更快。由于血管病变和视网膜病变是最终影响大多数糖尿病患者的衰弱性并发症，因此充分了解其发展机制对于设计有效的治疗干预措施非常重要。

DESCRIPTION (provided by applicant): The pathogenic processes that give rise to microangiopathic retinopathy and other vascular complications in diabetes are poorly understood. Several new lines of evidence have pointed toward inflammation as playing a heretofore unrecognized role. Retinal cells and vasculature and other self cells are protected from attack by autologous complement proteins by a set of intrinsic membrane regulatory proteins. These regulators are the decay accelerating factor (DAF or CD55), the membrane cofactor protein (MCP or CD46), and the membrane inhibitor of reactive lysis (CD59). Previous studies from our lab have shown that all three surface proteins are highly expressed in the retina and its associated vasculature in levels similar to those on glomerular cells and on systemic vasculature, sites where intrinsic regulatory activity is critical. In recent in vitro work, we have shown that DAF's regulatory function is 1) >90% inactivated by incubation with glucose or ribose, 2) rapidly abrogated by methylglyoxal incubation, and 3) lost due to modification of one or more active site lysine and arginine residues, the latter to argprymidine. In in vivo work, we have shown that endogenous DAF protein isolated from diabetic retinas is modified by several sugar adducts including argpyrimidine. The proposed studies are directed toward 1) determining the functional effects of chemical modifications in DAF, MCP, (and CD59) that are induced by hyperglycemia and other metabolic abnormalities that pertain in the diabetic state, 2) structurally characterizing the types and sites of the modifications on the regulators, 3) analyzing the functions and structures of endogenous DAF, MCP, (and CD59) proteins isolated from retinas and other tissues of diabetics, and 4) examining whether the pathological changes that are associated with retinopathy and other diabetic complications develop more rapidly in Daf1-/- (murine DAF homolog), Crry-/- (murine MCP surrogate), CD59a-/- (murine CD59 homolog) and double Daf1-/- / -/- Curry-/- or Daf1-/- / CD59a-/- mice experimentally made diabetic with streptozotocln. Since vasculopathy and retinopathy are debilitating complications that eventually affect most patients with diabetes, fully understanding the mechanisms involved in their development is important in designing effective therapeutic interventions.