Enzyme Therapy for PXE: Breaking the Barrier of Ectopic Calcification

PXE 酶疗法：打破异位钙化的障碍

• 批准号: 10689263
• 负责人: Qiaoli Li
• 金额: $ 20.95万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 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/10689263
• 关键词: Alkaline Phosphatase; Alleles; Animals; Biological; Biological Availability; Biological Response Modifier Therapy; Calcinosis; Cardiovascular system; Characteristics; Clinical; Clinical Management; Clinical Trials; Collaborations; Connective Tissue; Connective and Soft Tissue; 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; Link; Liver; Loss of Heterozygosity; Mediating; Membrane; Metabolic; Modality; Molecular Target; Morbidity - disease rate; Mus; Mutation; Oral; Other Genetics; Outcome; Pathologic; Pathology; Patient advocacy; Patients; Physiological; Plasma; Play; Prevention; Protein Engineering; Protein Isoforms; Protein phosphatase; Proteins; Pseudoxanthoma Elasticum; Rattus; Recombinants; Research; Rodent Model; Role; Skin; Supplementation; System; Testing; Tissues; Universities; Wild Type Mouse; advocacy organizations; 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; novel therapeutic intervention; pharmacologic; phosphatase inhibitor; pre-clinical; preclinical development; preclinical study; prevent; prototype; small molecule inhibitor; therapeutic development; treatment strategy

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 假阳性瘤（PXE）是一种异位钙化的遗传疾病，发病率相当大， 由于结缔组织中羟基磷灰石晶体的沉积而导致的死亡率。虽然确定了ABCC6 作为20年前PXE的致病基因，该疾病机制刚刚揭幕，并且有 目前仍未进行病理钙化的有效或特定治疗方法。我们以前已经开发了 PXE的鼠标模型表征，这些小鼠为临床前开发提供了平台 目前棘手的疾病的治疗剂。 PXE中的关键病理特征是还原 在循环水平的无机焦磷酸盐（PPI）中，钙化的关键内源性抑制剂。因此， 我们在此提出的研究的目标是在临床前研究中使用我们的鼠标模型来开发安全和 通过细胞外PPI水平归一化可以预防PXE异位钙化的有效治疗方法。 我们已经将ENPP1和TNAP蛋白确定为PPI稳态的关键调节剂。 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和后者 水解PPI。我们已经产生了重组ENPP1酶生物学和强大的初步数据 证明这种治疗性生物学在PXE的小鼠模型中升高了等离子体PPI水平及其循环 可以通过TNAP的药理抑制来扩展半衰期。基于这些发现和已知的 ENPP1和TNAP的酶活性，我们提出了使用重组的血浆PPI的调节 ENPP1酶，TNAP抑制剂或两种方法的组合代表了一种创新的策略 防止由于PPI缺乏而产生的异位钙化。为了检验这一假设，我们 建议利用遗传和药理方法来定义抑制TNAP的机制 通过补充ENPP1酶扩展PPI的血浆半衰期，然后防止和/或 减少PXE小鼠模型中的异位钙化。我们的团队具有必要的研究专业知识 ENPP1-PPI-TNAP轴和适当的小鼠模型以完成这些研究。 总的来说，我们预计拟议的研究将提供来自 临床前方法将允许开发新的治疗方法，用于异位钙化患者 pxe。如果成功，我们的发现将广泛地推进异位钙化的临床管理，因为PPI 缺乏在其他遗传和获得性疾病的异位钙化发展中起着重要作用。