Role of Aldose Reductase in Diabetic Complications

 描述（由申请人提供）：我们最近已经证明，醛糖还原酶（AR）是一种催化活性氧诱导的脂质醛及其谷胱甘肽（GSH）-缀合物（GS-LDA）还原的酶，是高血糖症、生长因子和细胞因子诱导的氧化和炎症信号的主要介质。我们之前资助的优秀奖研究表明，抑制AR可以阻止高糖诱导的血管细胞生长、NF-KB信号体激活以及NF-kB依赖性炎症标志物的表达。我们还发现，抑制AR可以防止糖尿病小鼠高血糖诱导的炎症信号传导.虽然我们已经确定AR催化的还原产物GS-DHN通过激活蛋白激酶C（PKC）下游的信号介导NF-κ B依赖性炎症标记物，但调节细胞氧化还原稳态导致免疫应答的分子机制尚不清楚。我们假设LDAs的谷胱甘肽缀合物是内源性危险信号，其激活NALP 3炎性体，导致细胞因子产生和炎症增加，从而导致糖尿病血管并发症。我们的目标是研究AR催化活性在氧化还原调节中发挥关键作用的机制 在糖尿病小鼠模型中，炎症介质传播分子途径，如内皮功能障碍和新生内膜形成。我们的长期目标是了解AR减少LDA及其谷胱甘肽结合物调节炎症信号传导的分子机制，这些炎症信号传导导致糖尿病血管并发症。通过使用特定的培养细胞和链脲佐菌素诱导的糖尿病的体内WT、AR、NALP 3、IL-1b和半胱天冬酶-1缺失小鼠模型，我们将研究AR催化的GS-LDA如何调节高血糖诱导的先天性免疫应答，该应答导致内皮功能障碍和新生内膜增生。我们的具体目标是：1）阐明AR催化LDA调节高脂血症中NF-kB依赖性促炎和Nrf-2依赖性抗炎通路的分子机制，2）检查LDA及其GSH缀合物作为内源性危险信号的信号传导事件，和3）描述AR产生的GS-LDA对NALP 3炎性体激活的贡献，NALP 3炎性体诱导内皮功能障碍并促进糖尿病中的新生内膜增生。完成拟议的研究将确定AR调节细胞氧化还原稳态，免疫反应和血管炎症的分子机制。这些研究也将为使用特异性抑制剂非达司他抑制AR奠定基础，非达司他已经进行了糖尿病神经病变的III期临床试验，并发现是安全的，作为预防和治疗糖尿病心血管并发症的新型抗炎方法。

 DESCRIPTION (provided by applicant): We have recently demonstrated that aldose reductase (AR), an enzyme that catalyzes the reduction of reactive oxygen species-induced lipid aldehydes and their glutathione (GSH)- conjugates (GS-LDAs), is the main mediator of oxidative and inflammatory signals induced by hyperglycemia, growth factors and cytokines. Our studies from previously funded merit award have shown that inhibition of AR prevents the high glucose-induced vascular cells growth and activation of NF-KB signalosome and expression of NF-kB- dependent inflammatory markers. We have also shown that inhibition of AR prevents hyperglycemia - induced inflammatory signaling in diabetic mice. Although, we have identified that AR-catalyzed reduced product, GS-DHN mediates NF-kB-dependent inflammatory markers by activating signals downstream to protein kinase C (PKC), the molecular mechanisms that regulate cellular redox homeostasis leading to immune response are not clearly understood. We hypothesize that glutathione conjugates of LDAs are endogenous danger signals that activate NALP3 inflammasome leading to increased cytokine production and inflammation that contribute to vascular complications in diabetes. Our goal is to investigate the mechanisms by which AR catalytic activity plays a critical role in redox regulation of inflammatory mediators which propagate molecular pathways such as endothelial dysfunction and neointimal formation in mouse models of diabetes. Our long-term goal is to understand the molecular mechanism(s) by which the reduction of LDAs and their glutathione conjugates by AR regulates inflammatory signaling that contributes to diabetic vascular complications. By using specific cultured cells and in vivo WT, AR, NALP3, IL-1b and caspase-1 null mouse models of streptozotocin-induced diabetes, we will examine how AR-catalyzed GS-LDAs regulate the hyperglycemia -induced innate immune response that causes endothelial dysfunction and neointimal hyperplasia. Our specific aims are to 1) elucidate the molecular mechanisms by which catalysis of LDAs by AR regulates NF-kB-dependent pro-inflammatory and Nrf-2-dependent anti-inflammatory pathways in hyperglycaemia, 2) examine the signaling events by which LDAs and their GSH conjugates act as endogenous danger signals, and 3) delineate the contribution of AR-generated GS-LDA to the activation of NALP3 inflammasome that induces endothelial dysfunction and promotes neointimal hyperplasia in diabetes. Completion of the proposed studies will identify the molecular mechanisms by which AR regulates cellular redox homeostasis, immune response and vascular inflammation. These studies will also lay the foundation for the use of AR inhibition by specific inhibitor, fidarestat that has already undergon phase-iii clinical trials for diabetic neuropathy and found to be safe, as a novel anti-inflammator approach in the prevention and treatment of diabetic cardiovascular complications.