INHIBITED INTRAMEMBRANEOUS BONE HEALING IN DIABETES

描述（由申请人提供）：糖尿病并发症部分由血清葡萄糖水平升高引起。这导致蛋白质的非酶糖化形成晚期糖化终产物（AGE）。AGE在糖尿病的许多并发症中起重要作用。骨质减少和低矿物质密度和骨骼脆弱是1型糖尿病的并发症，被称为“糖尿病性骨病”。令人惊讶的是，关于AGE在调节骨愈合、骨形成和成骨细胞功能中的作用知之甚少。例如，晚期糖基化终末产物（AGEs）受体的存在和活性尚未在成骨细胞中报道。这项研究的主要假设是AGE通过结合和激活成骨细胞中的β-淀粉样蛋白来抑制骨愈合和形成。我们认为，这导致NF κ B激活和转录抑制以及关键成骨细胞生长因子和细胞外基质基因的下调。 目的1将在体内测量选定的生长因子和细胞外基质产物（BMP-1、BMP- 2、BMP-4和I型胶原）在糖尿病和非糖尿病小鼠中形成的愈合颅骨缺损中的表达。将在Balb/c小鼠中通过多次低剂量链脲佐菌素方案诱导糖尿病;将在非化学诱导的鼠糖尿病模型（NOD品系）中进行选定的研究。将通过定量组织形态学和定量免疫组织化学测量来确定糖尿病动物中骨愈合的抑制程度和β-淀粉样蛋白的表达模式。研究将通过将AGE局部应用于非糖尿病小鼠的颅骨缺损来直接确定AGE在减少糖尿病骨形成中的作用。通过测量对愈合的抑制和对相同生长因子和细胞外基质产物的调节来确定其模拟糖尿病骨的程度。 目的2将在体外原代大鼠成骨细胞培养中确定AGE通过活化NF-κ B抑制成骨细胞生长因子和I型胶原的产生。骨功能阻断抗体研究将确定AGE/RAGE依赖性NF-κ B激活机制在特定成骨细胞基因的调节。NF-κ B活化在下调靶成骨细胞基因中的作用将通过用超阻遏物32A/36 A IKB-α（NF-κ B活化的有效和特异性抑制剂）转染直接确定。这些研究将确定一种新的机制，有助于糖尿病性骨病;并应导致确定新的治疗治疗目标，为这一日益普遍的临床条件。

DESCRIPTION (provided by applicant): Complications of diabetes result in part from elevated serum glucose levels. This leads to non-enzymatic glycation of proteins to form advanced glycation end products (AGE's). AGE's play a significant role in many complications of diabetes. Osteopenia and low mineral density and weak bones is a complication of Type 1 diabetes and is known as "diabetic bone disease". Surprisingly little is known regarding the role of AGE's in modulating bone healing, bone formation, and osteoblast function. For example, the presence and activity of the receptor for advanced glycation end products (RAGE) has not been reported in osteoblasts. The principal hypothesis of the proposed research is that AGE's inhibit bone healing and formation by binding and activating RAGE in osteoblasts. We propose that this results in NFKB activation and transcriptional repression and down-regulation of key osteoblast growth factors and extracellular matrix genes. Aim 1 will measure in vivo the expression of selected growth factors and extracellular matrix products (BMP-1, BMP- 2, BMP-4, and type I collagen) in healing calvaria defects made in diabetic and non-diabetic mice. Diabetes will be induced by the multiple low dose streptozotocin protocol in Balb/c mice; selected studies will be performed in the nonchemically-induced murine diabetic model (NOD strain). The degree of inhibition of bone healing in diabetic animals and expression patterns of RAGE will be determined by quantitative histomorphometric and quantitative immunohistochemical measurements. Studies will directly determine the role of AGE's in diminished diabetic bone formation by local application of AGE's to calvaria defects in non-diabetic mice. The degree to which this mimics diabetic bone will be determined by measuring inhibition of healing and regulation of the same growth factors and extracellular matrix products. Aim 2 will determine in vitro in primary rat osteoblast cell cultures that AGE's inhibit production of osteoblast growth factors and type I collagen via RAGE activated NF-KB. RAGE function blocking antibody studies will identify the AGE/RAGE-dependent NF-KB activation mechanism in the regulation of the specified osteoblast genes. The role of NF-KB activation in down-regulating target osteoblast genes will be directly determined by transfection with the super-repressor 32A/36A IKB-alpha, a potent and specific inhibitor of NF-KB activation. These studies will identify a new mechanism that contributes to diabetic bone disease; and should lead to the identification of new therapeutic treatment targets for this increasingly prevalent clinical condition.