CaP, crystal responsible for idiopathic nephrolithasis

CaP，导致特发性肾结石的晶体

• 批准号: 7219393
• 负责人: SAEED R. KHAN
• 金额: $ 22.4万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7219393
• 关键词: Adherence; Adhesions; Age; Apatites; CTF1 gene; Calcium; Calcium Oxalate; Calculi; Cell Communication; Cell Line; Cell membrane; Cell surface; Cells; Cessation of life; Chemotactic Factors; Chronic; Condition; Consensus; Crystal Formation; Crystallization; Deposition; Disease; Distal; Duct (organ) structure; Endocytosis; England; Environment; Epithelial; Epithelial Cells; Exposure to; Fibroblasts; Free Radicals; Giant Cells; Henle' s loop; Human; Hydroxyapatites; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory Response; Investigation; Kidney; Kidney Calculi; Kidney Papilla; Kidney Part; Lead; Lipid Peroxidation; Location; MDCK cell; Membrane; Modification; Molecular; Monocyte Chemoattractant Protein-1; Nephrolithiasis; Nephrons; Numbers; Pathogenesis; Patients; Phase; Play; Population; Prevalence; Process; Production; Reaction; Recurrence; Renal tubule structure; Research; Research Personnel; Resistance; Role; Saudi Arabia; Serum Proteins; Side; Solid; Solutions; Surface; System; Testing; Tubular formation; United States National Institutes of Health; Urinary Calculi; Urine; base; bikunin; brushite; calcium phosphate; cell injury; cost; experience; interstitial; kidney cell; macromolecule; macrophage; men; monocyte; osteopontin; prevent; programs; renal epithelium; response; surface coating; symposium; theories; tissue culture; urinary; urolithiasis

DESCRIPTION (provided by applicant): Nephrolithksis is a result of crystal formation and retention within the kidneys. Several studies have shown that conditions are favorable for the formation of calcium phosphate (CaP) in early segments of the nephron namely proximal tubules and the loops of Henle. It is proposed that CaP formed in early segments promote nucleation of calcium oxalate (CaOx) in the collecting ducts. Renal epithelial cells exposed to non-physiologically high levels of oxakte and/or CaOx crystals experience both structural and functional changes, which may eventually lead to cell injury and death. These changes also promote crystal attachment to cell surfaces and retention within the renal tubules. As a protective response, CaOx crystals are often endocytosed at the luminal side and exocytosed into die interstitium where they are processed by the inflammatory defense indicated by the presence of monocytes, macrophages and giant cells. Interestingly CaP crystals seen in the renal interstitium do not induce an inflammatory response. Even though CaP is considered the primary crystal and crystal induced changes in epithelial cells are essential for crystal retention, studies have yet to investigate crystal cell interactions between CaP and renal epithelial cells. CaP has also been shown to dissolve in the acidic environment of the collecting ducts. It is our hypothesis that crystals formed in the urine contain a surface coat, which inhibits crystal dissolution. We also hypothesize that similar to CaOx crystals, an exposure to crystals of CaP also challenges the cells and leads to alterations in renal epithelial cells, which promote crystal retention. We propose to test our hypotheses by exposing proximal tubular origin HK-2 and collecting duct origin MDCK cells to CaP crystals in culture. Two forms of CaP, inorganic apatite and brushite as well as apatite and brushite coated with urinary macromolecules will be used. In addition we propose to investigate the interaction between CaP crystals and renal interstitial fibroblasts to find out why renal interstitial CaP deposits do not cause inflammation. We have the following Specific Aims. 1. To confirm that CaP crystals coated with urinary macromolecules, are resistant to dissolution and good nucleators of CaOx in acidic environment of collecting ducts. 2. To probe that exposure to CaP crystals is associated with renal epithelial cellular injury and that exposure of renal epithelial cells to CaP crystals causes free radical production and lipid peroxidation. 3. To show that production by renal epithelial cells of crystallization modulators such as osteopontin (OPN) and bikunin and a-1 microglobulin is upregulated on exposure to CaP crystals. 4. To demonstrate that CaOx crystal adherence to renal epithelial cells is increased by their previous exposure to CaP crystals and nucleation of CaOx crystals is promoted by surface membranes of the cells pre-exposed to CaP crystals. 5. To determine the molecular mechanism for the inability of renal interstitial CaP crystals to provoke an inflammatory reaction.

描述（由申请人提供）：肾结石是肾脏内晶体形成和滞留的结果。一些研究表明，条件有利于形成磷酸钙（CaP）在肾元的早期段，即近端小管和Henle环。早期形成的CaP促进了集管中草酸钙（CaOx）成核。肾上皮细胞暴露于非生理性高水平的oxakte和/或CaOx晶体会经历结构和功能变化，最终可能导致细胞损伤和死亡。这些变化也促进晶体附着于细胞表面并在肾小管内保留。作为一种保护性反应，CaOx晶体通常在管腔侧被内吞，并胞泌到细胞间质，在细胞间质被单核细胞、巨噬细胞和巨细胞的存在所指示的炎症防御处理。有趣的是，肾间质中可见的CaP晶体不会引起炎症反应。尽管CaP被认为是原代晶体，并且上皮细胞中晶体诱导的变化对晶体保留至关重要，但尚未有研究调查CaP与肾上皮细胞之间的晶体细胞相互作用。CaP也被证明在收集管的酸性环境中溶解。我们的假设是，在尿液中形成的晶体含有一层表面涂层，可以抑制晶体的溶解。我们还假设，与CaOx晶体类似，暴露于CaP晶体也会挑战细胞并导致肾上皮细胞的改变，从而促进晶体保留。我们建议通过将近端管源HK-2和收集管源MDCK细胞暴露于CaP晶体培养中来验证我们的假设。两种形式的CaP，无机磷灰石和刷石，以及磷灰石和刷石包裹尿液大分子将被使用。此外，我们建议研究CaP晶体与肾间质成纤维细胞之间的相互作用，以找出肾间质CaP沉积不引起炎症的原因。我们有以下具体目标：以尿液大分子包覆的CaP晶体，在收集管酸性环境下具有抗溶解性和良好的CaOx成核剂。2. 探讨暴露于CaP晶体与肾上皮细胞损伤有关，以及肾上皮细胞暴露于CaP晶体导致自由基产生和脂质过氧化。3. 表明肾上皮细胞的结晶调节剂如骨桥蛋白（OPN）、比库宁和a-1微球蛋白的产生在暴露于CaP晶体时被上调。4. 为了证明CaOx晶体对肾上皮细胞的粘附性因其先前暴露于CaP晶体而增加，并且预先暴露于CaP晶体的细胞表面膜促进了CaOx晶体的成核。5. 确定肾间质CaP晶体不能引起炎症反应的分子机制。