Targeting angiogenesis for fracture nonunion treatment under inflammatory diseases

靶向血管生成治疗炎症性疾病下的骨折不愈合

• 批准号: 10030432
• 负责人: Jianjun Guan
• 金额: $ 56.53万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-09 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10030432
• 关键词: Address; Affect; Biocompatible Materials; Bone callus; CXCL12 gene; Cell physiology; Cells; Chondrocytes; Chronic; Clinical; Clinical Research; DNA Methylation; DNA Modification Methylases; DNMT3B gene; Data; Defect; Diabetes Mellitus; Disease; Down-Regulation; Elderly; Endothelial Cells; Enzymes; Epigenetic Process; Failure; Fracture; Fracture Healing; Gene Expression; Health Care Costs; Human; Impairment; In Vitro; Inflammation; Inflammatory; Interleukin-1 beta; K/BxN model; Kinetics; Knowledge; Lead; Ligands; Mediating; Methylation; Molecular; Mus; Operative Surgical Procedures; Pathway interactions; Patients; Pharmacology; Population; Procedures; Process; Rheumatoid Arthritis; Role; Serum; Signal Transduction; Smoking; Therapeutic; Therapeutic Effect; Therapeutic Intervention; Treatment Efficacy; Tube; United States; Work; angiogenesis; cell motility; chemokine; comorbidity; cytokine; diabetic; disability; epigenome; experience; gain of function; healing; improved; in vivo; loss of function; novel; novel therapeutic intervention; older patient; osteopontin; protective effect; repaired; restoration; scaffold

ABSTRACT Fracture nonunion poses a significant clinical problem. In the United States, approximately 1.6 million bone fractures encounter prolonged healing or nonunion each year. Fracture nonunion treatment usually involves complicated and massive procedures in practice, and sometimes needs multiple surgeries, therefore increases the cost of health care and results in marked patient disability. The major population bearing with these clinical complications are patients with inflammatory conditions, e.g, elder patients, smoking, diabetic or rheumatoid arthritis (RA) patients, highlighting the potential deleterious role of chronic systemic inflammation in fracture r epair. The overarching hypothesis of this proposal is that chronic inflammation results in fracture nonunion through Dnmt3b downregulation mediated angiogenesis defect, and local delivery of OPN and CXCL12 restores angiogenesis and fracture repair under inflammatory conditions. This hypothesis is supported by our preliminary data wherein we show that Dnmt3b is highly expressed in fracture callus during fracture repair and Dnmt3b is the major DNA methyltransferase (Dnmt) responsive to cytokines in MPCs. Relevant to our proposal, we provide evidence that inflammatory signals inhibit Dnmt3b in an NF-κB-dependent manner. Consistently, mice with Dnmt3b loss-of-function (LOF) in chondrocytes display impaired angiogenesis and fracture repair; and Dnmt3b gain-of-function (GOF) in chondrocytes shows protective effect from inflammation in vitro and accelerates fracture repair in mice. Mechanistically, angiogenesis defect mediated by inflammation and Dnmt3b LOF coincide with downregulation of OPN (Osteopontin) and CXCL12 (C-X-C Motif Chemokine Ligand 12) and exogenous OPN and CXCL12 can restore angiogenesis capacity in vitro. To further examine the efficacy of local delivery of OPN and CXCL12 in vivo, we have developed an optimized biomaterial sheet loaded with OPN and CXCL12 and showed a robust angiogenesis process and a restoration of fracture union in RA mice. Three main Specific Aims are proposed. Specific Aim 1 will delineate the mechanism by which inflammation reduces angiogenesis via downregulating Dnmt3b during fracture repair. Specific Aim 2 will determine the optimal release kinetics of OPN and CXCL12 on angiogenesis. Specific Aim 3 will determine the therapeutic effect of sustained OPN and CXCL12 release on angiogenesis and fracture nonunion in mice. The proposed studies will enhance our understanding of mechanisms by which systemic inflammation (via the NF- κB pathway) affects the angiogenic process through Dnmt3b. This work will establish an important therapeutic option to improve the angiogenesis and fracture healing.

抽象的 骨折不愈合造成严重的临床问题。在美国，大约有 160 万块骨头 骨折每年都会遇到长时间愈合或骨不连的情况。骨折不愈合治疗通常包括 实践中手术复杂、规模大，有时需要多次手术，因此增加 医疗保健费用并导致患者明显残疾。患有这些临床症状的主要人群 并发症是患有炎症的患者，例如老年患者、吸烟、糖尿病或类风湿患者 关节炎（RA）患者，强调了慢性全身炎症对骨折的潜在有害作用 维修。 该提案的总体假设是慢性炎症导致骨折不愈合 通过 Dnmt3b 下调介导的血管生成缺陷，以及 OPN 和 CXCL12 的局部递送恢复 炎症条件下的血管生成和骨折修复。这个假设得到了我们初步的支持 数据显示，Dnmt3b 在骨折修复过程中在骨折愈伤组织中高表达，并且 Dnmt3b MPC 中对细胞因子有反应的主要 DNA 甲基转移酶 (Dnmt)。与我们的提案相关，我们提供 有证据表明炎症信号以 NF-κB 依赖性方式抑制 Dnmt3b。一致地，小鼠 软骨细胞中的 Dnmt3b 功能丧失 (LOF) 显示血管生成和骨折修复受损；和Dnmt3b 软骨细胞的功能获得（GOF）在体外显示出对炎症的保护作用并加速 小鼠骨折修复。从机制上讲，炎症和 Dnmt3b LOF 介导的血管生成缺陷 与 OPN（骨桥蛋白）和 CXCL12（C-X-C 基序趋化因子配体 12）的下调同时发生 外源性OPN和CXCL12可以在体外恢复血管生成能力。进一步检验局部效果 为了在体内递送 OPN 和 CXCL12，我们开发了一种优化的生物材料片，负载有 OPN 和 CXCL12 CXCL12 并在 RA 小鼠中显示出强大的血管生成过程和骨折愈合的恢复。 提出了三个主要具体目标。具体目标 1 将描述机制 炎症通过在骨折修复过程中下调 Dnmt3b 来减少血管生成。具体目标 2 将 确定 OPN 和 CXCL12 对血管生成的最佳释放动力学。具体目标 3 将决定 持续释放 OPN 和 CXCL12 对小鼠血管生成和骨折不愈合的治疗作用。这 拟议的研究将增强我们对全身炎症（通过 NF- κB 通路）通过 Dnmt3b 影响血管生成过程。这项工作将建立一个重要的治疗方法 改善血管生成和骨折愈合的选择。