Factors Determining Protein Losing Enteropathy

描述（由申请人提供）：蛋白质丢失性肠病（PLE）的基础及其发展方式尚不清楚，也没有动物模型。我们建议开发一个模型系统来更好地理解PLE，并根据临床观察和我们最近的发现测试一种新的治疗方法。先天性糖基化障碍（CDG）患者在肠道和全身感染等环境损害后发生PLE。其他糖基化正常的儿童在接受Fontan手术矫正先天性单室心脏后数月至数年发生PLE。可变的发病提示遗传/环境联合病因。我们注意到CDG患者和ple后Fontan患者特异性地从小肠上皮细胞基底外侧表面丢失硫酸肝素（HS）蛋白多糖（HSPG）。这也发生在fontan后的患者中。在CDG患者中，当PLE消退时，HSPG再次恢复正常。这使得肠细胞HSPG成为相关细胞类型中唯一已知的PLE分子标记物。我们假设局部HSPG的丢失，加上静脉压升高的全身性促炎条件导致了PLE。我们的初步数据支持这些因素的强大协同作用。这些发现使我们能够构建和测试PLE的小鼠模型。我们将研究正常小鼠和HS-缺陷小鼠以及HS-缺陷单层细胞的肠道蛋白损失。在AIM 1中，我们确定了细胞因子长期暴露对小鼠的影响以及hs -细胞因子在细胞培养中的协同作用机制。在AIM 2中，我们测量了压力增加对正常和hs缺陷小鼠蛋白质损失的影响。AIM 3研究正常小鼠和hs缺陷小鼠血压升高和细胞因子的协同作用。在Aim 4中，我们测试了一种新型改性肝素预防或逆转蛋白质损失的能力。结果将扩展我们对PLE如何发展的理解，并为研究其他治疗方法提供一个模型系统。在未来，我们的工作可能有助于确定Fontan患者发展为PLE的风险，并提供新的治疗方法，可以在我们的这种神秘疾病的模型中进行测试。公共卫生相关性：通过肠道丢失血浆蛋白（蛋白质丢失性肠病，PLE）可能是致命的。PLE患儿有许多不同的遗传和获得性疾病。他们是如何以及为什么突然发展成PLE的尚不清楚，也没有人有动物模型来测试新兴疗法。我们建议制作小鼠PLE模型，并测试我们实验室开发的一种新疗法。我们的长期目标是识别高危患者并为他们提供治疗。

DESCRIPTION (provided by applicant): The basis of protein-losing enteropathy (PLE) and how it develops are unknown and no animal models exist. We propose to develop a model system to better understand PLE and test a novel therapeutic based on clinical observations and our recent discoveries. Patients with Congenital Disorders of Glycosylation (CDG) develop PLE after environmental insults such as enteric and generalized infections. Other children with normal glycosylation develop PLE months to years after their Fontan surgery to correct congenital univentricular hearts. The variable onset suggests a combined genetic/environmental etiology. We noted that CDG patients and PLE-stricken post- Fontan patients lose heparan sulfate (HS) proteoglycans (HSPG) specifically from the basolateral surface of small intestine epithelial cells. This also occurs in post-Fontan patients. In CDG patients, HSPG normalizes again when PLE resolves. This makes enterocyte HSPG the only known molecular marker of PLE in a relevant cell type. We hypothesize that localized loss of HSPG, plus a general systemic pro-inflammatory condition in a setting of increased venous pressure causes PLE. Our preliminary data supports a robust synergism of these factors. These findings allow us to construct and test a mouse model for PLE. We will study enteric protein loss in normal and HS- deficient mice and in HS-deficient cell monolayers. In AIM 1, we determine the effects of prolonged cytokine exposure in mice and the mechanism of HS-cytokine synergism in cell culture. In AIM 2 we measure the effects of increased pressure on protein loss in normal and HS-deficient mice. AIM 3 studies the synergy of increased pressure and cytokines in normal and HS-deficient mice. In Aim 4 we test the ability of a novel modified heparin to prevent or reverse protein loss. The results will extend our understanding of how PLE develops and provide a model system to study other therapeutics. In the future, our work may help identify Fontan patients at risk for developing PLE and provide insights into new therapeutics that can be tested in our model of this enigmatic disease. PUBLIC HEALTH RELEVANCE: Losing plasma proteins through the intestine (protein-losing enteropathy, PLE) can be fatal. Children with PLE have many different inherited and acquired diseases. How and why they suddenly develop PLE is not understood, and no one has an animal model to test emerging therapies. We propose to make a mouse model of PLE and test a novel therapy developed in our laboratory. Our long-range goal is to identify at-risk patients and provide a therapy for them.