Enzyme Therapy for PXE: Breaking the Barrier of Ectopic Calcification

PXE 酶疗法：打破异位钙化的障碍

基本信息

批准号：
10527964
负责人：
Qiaoli Li
金额：
$ 18.75万
依托单位：
THOMAS JEFFERSON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-08-25 至 2024-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10527964
关键词：
Alkaline Phosphatase Alleles Animals Biological Biological Response Modifier Therapy Calcinosis Cardiovascular system Characteristics Clinical Clinical Management Clinical Trials Collaborations Connective Tissue Connective and Soft Tissue Crystallization Data Defect Deposition Dermatologist Development Diphosphates Disease Dose Drug Kinetics Durapatite Elastic Fiber Enzymes Eye Genes Genetic Genetic Diseases Goals Half-Life Heritability Homeostasis Human Hydroxyapatites Inflammatory Injections International Lead Link Liver Mediating Metabolic Modality Molecular Target Morbidity - disease rate Mus Mutation Oral Other Genetics Outcome Pathologic Pathology Patient advocacy Patients Pharmacology Physiological Plasma Play Prevention Protein Engineering Protein Isoforms Protein phosphatase Proteins Pseudoxanthoma Elasticum Rattus Recombinants Research Rodent Model Role Skin Supplementation Testing Tissues Universities Wild Type Mouse advocacy organizations base bench to bedside calcification calcification inhibitor calcium phosphate precipitation clinical care effective therapy enzyme replacement therapy enzyme therapy extracellular improved inhibitor innovation international center loss of function mutation mineralization mortality mouse model novel novel strategies phosphatase inhibitor pre-clinical preclinical development preclinical study prevent prototype small molecule inhibitor therapeutic development treatment strategy

项目摘要

ABSTRACT Pseudoxanthoma elasticum (PXE) is a genetic disorder of ectopic calcification with considerable morbidity and mortality due to deposition of hydroxyapatite crystals in the connective tissues. Though ABCC6 was identified as the causative gene for PXE 20 years ago, the disease mechanism was just recently unveiled and there is currently still no effective or specific treatment for the pathologic calcification. We have previously developed and characterized mouse models for PXE, and these mice provide the platform for preclinical development of therapeutics for this currently intractable condition. A critical pathological characteristic in PXE is the reduction in circulating levels of inorganic pyrophosphate (PPi), a key endogenous inhibitor of calcification. Therefore, the goal of the research we propose herein is to use our mouse models in preclinical studies to develop safe and effective treatments that can prevent ectopic calcification in PXE by normalization of extracellular PPi levels. We have identified ENPP1 and TNAP proteins as key regulators of PPi homeostasis. ENPP1 and TNAP have opposing actions in maintaining extracellular PPi concentrations, the former generating PPi and the latter hydrolyzing PPi. We have generated a recombinant ENPP1 enzyme biologic and our strong preliminary data demonstrate that this therapeutic biologic raised plasma PPi levels in a mouse model of PXE, and its circulating half-life can be extended by pharmacologic inhibition of TNAP. Based upon these findings and the known enzymatic activities of ENPP1 and TNAP, we propose that modulation of plasma PPi, either using a recombinant ENPP1 enzyme, TNAP inhibitors, or a combination of both approaches, represents an innovative strategy to prevent the ectopic calcification that arises as a consequence of PPi deficiency. To test this hypothesis, we propose to utilize genetic and pharmacologic approaches to define mechanisms by which inhibition of TNAP extends the plasma half-life of PPi from ENPP1 enzyme supplementation, and subsequently prevents and/or diminishes the ectopic calcification in a mouse model of PXE. Our team has the requisite research expertise in the ENPP1-PPi-TNAP axis and appropriate mouse models to complete these studies. Collectively, we anticipate that the proposed studies will provide critical translational information from preclinical approaches that will allow development of novel treatments for ectopic calcification in patients with PXE. If successful, our findings will advance clinical management of ectopic calcification broadly, as PPi deficiency plays an important role in development of ectopic calcification in other genetic and acquired disorders.

抽象的弹性假黄瘤（PXE）是一种异位钙化的遗传性疾病，具有相当高的发病率和由于羟基磷灰石晶体沉积在结缔组织中而导致死亡。虽然 ABCC6 已被识别作为20年前PXE的致病基因，其发病机制最近才被揭示，目前尚不清楚。目前对于病理性钙化尚无有效或特异的治疗方法。我们之前已经开发并表征了 PXE 的小鼠模型，这些小鼠为 PXE 的临床前开发提供了平台针对这种目前棘手的病症的治疗方法。 PXE 的一个关键病理特征是减少无机焦磷酸盐 (PPi) 的循环水平，PPi 是钙化的关键内源性抑制剂。因此，我们在此提出的研究目标是在临床前研究中使用我们的小鼠模型来开发安全且通过使细胞外 PPi 水平正常化，可以预防 PXE 异位钙化的有效治疗。我们已经确定 ENPP1 和 TNAP 蛋白是 PPi 稳态的关键调节因子。 ENPP1 和 TNAP 在维持细胞外 PPi 浓度方面具有相反的作用，前者产生 PPi，后者产生 PPi 水解PPi。我们已经生成了重组 ENPP1 酶生物制剂和强有力的初步数据证明这种治疗性生物制剂可提高 PXE 小鼠模型的血浆 PPi 水平，及其循环通过药物抑制 TNAP 可以延长半衰期。基于这些发现和已知的 ENPP1 和 TNAP 的酶活性，我们建议通过使用重组蛋白来调节血浆 PPi ENPP1 酶、TNAP 抑制剂或两种方法的组合代表了一种创新策略预防因 PPi 缺乏而引起的异位钙化。为了检验这个假设，我们提议利用遗传和药理学方法来定义抑制 TNAP 的机制通过补充 ENPP1 酶延长 PPi 的血浆半衰期，从而预防和/或减少 PXE 小鼠模型中的异位钙化。我们的团队拥有必要的研究专业知识 ENPP1-PPi-TNAP 轴和适当的小鼠模型来完成这些研究。总的来说，我们预计拟议的研究将提供关键的转化信息临床前方法将允许开发异位钙化患者的新疗法 PXE。如果成功，我们的研究结果将广泛推进异位钙化的临床管理，如 PPi 缺乏在其他遗传性和获得性疾病中异位钙化的发展中起着重要作用。