Fibrocyte Contribution to Systemic Fibrosis in Chronic Kidney Disease

纤维细胞对慢性肾脏病系统性纤维化的贡献

• 批准号: 8635030
• 负责人: BRENT WAGNER
• 金额: --
• 依托单位: SOUTH TEXAS VETERANS HEALTH CARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-10-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8635030
• 关键词: Acute; Address; Affect; Alkaline Phosphatase; Animals; Area; Biodistribution; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; CC chemokine receptor 7; CD34 gene; Cells; Cellularity; Chemicals; Chemotactic Factors; Chronic; Chronic Kidney Failure; Contrast Media; Data; Deposition; Dermal; Dermis; Disease; Dose; End stage renal failure; Engraftment; Exposure to; Extracellular Matrix; Femur; Fibroblasts; Fibrosis; Flow Cytometry; Gadolinium; Generations; Genetic; Goals; Healthcare Systems; Heart; Human; Impairment; In Situ; In Vitro; Infiltration; Kidney; Kidney Diseases; Kidney Failure; Lead; Lesion; Leukocytes; Liver; Lung; Magnetic Resonance; Magnetic Resonance Imaging; Marrow; Measures; Mediating; Mediator of activation protein; Medical; Mesenchymal; Mesenchymal Stem Cells; Modeling; Monocyte Chemoattractant Protein-1; Mus; Muscle; Nature; Nephrectomy; Organ; Outcome; PTPRC gene; Pathogenesis; Pathology; Patients; Pattern; Peripheral; Play; Population; Process; Procollagen; Proteins; Publications; Randomized; Rattus; Recruitment Activity; Relative (related person); Renal function; Resistance; Respiratory Diaphragm; Risk Factors; Rodent Model; Role; Site; Skin; Skin Abnormalities; Spleen; Stimulus; Testing; Time; Tissues; Transgenic Organisms; Transplantation; Veterans; Wild Type Mouse; Work; base; bone; chemokine; chemokine receptor; cytokine; design; gadodiamide; gadolinium oxide; in vivo; precursor cell; progenitor; programs; prophylactic; public health relevance; research study; skin lesion

Exposure to gadolinium-based magnetic resonance imaging (MRI) contrast is a major risk factor in the acquisition of nephrogenic systemic fibrosis (NSF), a severely debilitating disease first recognized in patients with acute or chronic renal impairment. MRI contrast agents heretofore were considered safe in these patients and thus indiscriminately used. Gadolinium-based contrast agents remain a mainstay for MR imaging and alternatives are still lacking. The applicant's preliminary data show that MRI contrast elicits a direct proliferative effect on human fibroblasts with an increase in extracellular matrix synthesis in vitro. Rats with renal insufficiency exposed to MRI contrast demonstrate significant skin abnormalities, including recruitment of bone marrow-derived cells. MRI contrast-treated mice similarly demonstrate skin fibrosis with dermal hypercellularity. Furthermore, gadolinium has been detected in affected rat and mouse skin as well as other organs (such as the kidneys and livers) from MRI contrast-treated animals. The overall objective of this proposal is to identify candidate mechanisms that trigger the aberrant pattern of fibrosis after exposure to gadolinium-based MRI contrast in the setting of renal insufficiency. The central hypothesis is that in the setting of renal insufficiency, MRI contrast exposure triggers a pro-fibrotic state in target organs, such as the skin. Subsequent generation of specific chemokines activate and recruit bone marrow-derived and circulating mesenchymal precursor cells, or fibrocytes, to the affected areas. These cells compound the fibrotic process by synthesizing and reducing the generation of extracellular matrix and inducing the proliferation of resident cells. Experiments will address the following Specific Objectives: 1a: Determine the mechanism by which gadolinium-based contrast induces NSF. The applicant has proven that bone marrow-derived cells constitute around 44% of the dermal cellularity in skin lesions. Whether gadolinium deposition in the skin elicits the generation of pro-fibrotic cytokines that lead to fibrocyte recruitment or if gadolinium stimulation in other sites, such as the bone marrow, programs fibroblast precursors to hone to specific sites is unknown. The applicant will test this by "priming" bone marrow donor (transgenic, "tagged") rats with exposure to MRI contrast and then transplanting this bone marrow into lethally-irradiated animals. 1b: Demonstrate that gadolinium-based contrast induces an increase in circulating fibrocytes. The effect of MRI contrast on the number of circulating fibrocytes at specific time points will be quantified in rats. 2a: Determine the chemokines and receptors responsible for recruitment of bone marrow-derived cells to specific tissues. The hypothesis is that the monocyte chemoattractant protein- (MCP-) 1/chemokine receptor 2 (CCR2) axis modulates the recruitment of fibrocytes in MRI contrast-induced systemic fibrosis. The chemical mediators that lead to the recruitment of circulating cells to NSF lesions is not well-explored. Resistance to NSF will be examined in animals with a genetic deficiency CCR2 will be explored. The role of this protein will be validated by using bone marrow transplant experiments where CCR2-deficient bone marrow is transplanted to normal (wild-type) mice and vice-versa. 2b: Test the hypothesis that biodistribution of gadolinium differs between normal renal function and renal insufficiency in mice and rats. Even though prior publications definitively indicate that the liver is a major reservoir for gadolinium in MRI-contrast treated rats and mice, the skin is invariably involved in NSF and to a far greater extent than any liver pathology in experimental animals found to date by the applicant. If the deposition of gadolinium is the nidus for triggering the disease, perhaps biodistribution of gadolinium differs between the states of renal sufficiency and insufficiency. Gadolinium accumulation in organs potentially affected in NSF (skin, lungs, heart, diaphragm, liver, spleen, bone, muscle) will be compared in animals with renal insufficiency (subtotal nephrectomies) and sham-treated controls. The findings will lead to a better understanding of how systemic fibrosis occurs and why certain organs are targeted.

暴露于钆基磁共振成像（MRI）造影剂是 肾源性系统性纤维化（NSF）的获得，这是一种首次在患者中发现的严重衰弱性疾病 急性或慢性肾损害。迄今为止，MRI造影剂在这些患者中被认为是安全的 因此被不加区别地使用。基于钆的造影剂仍然是MR成像的支柱， 仍然缺乏替代办法。申请人的初步数据表明，MRI造影剂可直接促进增殖性肿瘤的发生。 对人成纤维细胞的影响，增加体外细胞外基质合成。大鼠肾 暴露于MRI造影剂不足显示出显著的皮肤异常，包括骨募集 骨髓来源的细胞。MRI对比剂处理的小鼠类似地表现出皮肤纤维化和真皮细胞过多。 此外，在受影响的大鼠和小鼠皮肤以及其他器官（如 肾脏和肝脏）。本建议的总体目标是 确定暴露于以下物质后触发异常纤维化模式的候选机制： 钆基MRI造影剂在肾功能不全的应用。核心假设是， 在肾功能不全的情况下，MRI造影剂暴露触发靶器官的促纤维化状态，例如 皮肤随后产生的特异性趋化因子激活并募集骨髓源性和循环性趋化因子。 间充质前体细胞或纤维细胞转移到受影响的区域。这些细胞复合纤维化过程 通过合成和减少细胞外基质的产生并诱导驻留细胞的增殖， 细胞实验将针对以下具体目标：1a：确定 钆基造影剂诱导NSF。申请人已证明骨髓来源的细胞 在皮肤损伤中占真皮细胞结构的约44%。皮肤中的钆沉积是否 导致纤维细胞募集的促纤维化细胞因子的产生，或者如果钆刺激在其他组织中， 部位，如骨髓，程序成纤维细胞前体骨到特定部位是未知的。的 申请人将通过暴露于MRI的“致敏”骨髓供体（转基因，“标记”）大鼠来测试这一点 然后将这些骨髓移植到受到致命辐射的动物体内。1B：证明 钆基造影剂诱导循环纤维细胞的增加。MRI对比剂对 在特定时间点对大鼠中循环纤维细胞的数量进行定量。2a：确定 趋化因子和受体，负责将骨髓来源的细胞募集到特定组织。 假设单核细胞趋化蛋白-（MCP-）1/趋化因子受体2（CCR 2）轴 调节MRI造影剂诱导的系统性纤维化中纤维细胞的募集。化学介质， 导致循环细胞向NSF病变募集的机制尚未得到充分研究。对NSF的抵抗将是 将探索在具有CCR 2遗传缺陷的动物中进行的检查。这种蛋白的作用将得到验证 通过使用骨髓移植实验，其中将CCR 2缺陷的骨髓移植到正常的 （野生型）小鼠，反之亦然。2b：检验钆的生物分布不同的假设 正常肾功能和肾功能不全之间的关系。尽管先前的出版物 明确表明肝脏是MRI造影剂治疗的大鼠和小鼠中钆的主要储存库， 皮肤总是参与NSF，并且在实验动物中比任何肝脏病理学都要大得多 申请人至今发现。如果钆的沉积是引发疾病的病灶， 钆的生物分布在肾功能不全和肾功能不全的状态之间是不同的。钆 在NSF中可能受影响的器官中蓄积（皮肤、肺、心脏、横膈膜、肝、脾、骨、肌肉） 将在肾功能不全（肾次全切除术）动物和假手术对照动物中进行比较。的 研究结果将有助于更好地了解系统性纤维化是如何发生的，以及为什么某些器官是靶向的。