Crystal Interactions in Renal Stone Disease

肾结石疾病是一种严重的健康问题，与严重的疼痛、痛苦和经济成本有关。5%到15%的人在70岁之前会出现尿路结石的症状，其中至少50%的人会有复发性结石疾病。本研究的重点是尿晶体在损伤肾乳头尖上皮上的附着。我们的研究是由工作假设驱动的，即晶体附着在乳头状上皮上需要细胞/组织损伤，包括细胞血浆脂质不对称性的丧失和/或细胞极性的丧失。采用两种特定的内髓集管（IMCD）细胞损伤模型。(1)质膜脂质不对称的丧失，导致磷脂酰丝氨酸从细胞膜的内叶向外叶呈现；(2)细胞内紧密连接破裂，导致质膜基底外侧和顶膜成分混合到改变的管腔细胞表面，从而导致细胞极性的丧失。在这两种模型中，损伤导致了顶膜组成/结构的改变，更重要的是将非晶体附着细胞转变为具有晶体附着的细胞。提出的研究分为三个具体目标，测试三个具体假设。他们将利用已建立的细胞培养和分离的灌注小管系统以及结石疾病的高血氧动物模型。研究将局限于人类尿路结石的四种最常见的晶体成分，即一水草酸钙（COM）和二水草酸钙（COD），碱性磷酸钙（磷灰石，AP）和尿酸（UA）晶体。具体目的：目的一：探讨尿环境对损伤的乳头集管细胞在改变的质膜表面分子晶体附着的影响。特定目的II：确定两个特定肾元段对确定的损伤和随后的晶体附着的相对敏感性。特定目的III：在动物模型中确定轻度慢性高草酸尿是否在过饱和条件和结晶尿发作时产生晶体附着之前的局部肾细胞损伤。

Kidney stone disease is a substantial health problem associated with significant pain, suffering, and economic costs. 5% to 15% of the population will have a symptomatic episode of a stone within the urinary tract by the age of 70 and at least 50% of these individuals will have recurrent stone disease. This grant focuses on the attachment of urinary crystals to injured kidney papillary tip epithelium. Our investigations are driven by the working hypothesis that crystal attachment to papillary epithelium requires cell/tissue injury that includes loss of cell plasma lipid asymmetry and/or loss of cell polarity. Two specific inner medullary collecting duct (IMCD) cell injury models will be employed. (i) the loss of plasma membrane lipid asymmetry resulting in the presentation of phosphatidylserine from the inner to the outer leaflet of the cell plasma membrane, and (ii) the loss of cell polarity as a result of intracellular tight junction breakdown resulting in the mixing of plasma membrane basolateral and apical membrane components to an altered luminal cell surface. In both models, injury leads to altered apical membrane composition/structure, and more importantly converts a non-crystal attaching cell into one that does attach crystals. The proposed studies are divided into three Specific Aims that test three specific hypotheses. They will utilize established cell culture and isolated perfused tubule systems and a hyperoxaluric animal model of stone disease. Investigations will be limited to the four most common crystalline components of human urinary tract stones, namely calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), basic calcium phosphate (apatite, AP), and uric acid (UA) crystals. The Specific Aims are: Specific Aim I: To determine in injured papillary collecting duct cells the influence of urinary environment on the molecular nature of crystal attachment in molecules on the altered plasma membrane surface. Specific Aim II: To determine the relative susceptibility of two specific nephron segments to defined injury and subsequent attachment of crystals. Specific Aim III: To determine in an animal model if mild chronic hyperoxaluria produces the localized nephron cell injury that precedes crystal attachment during supersaturation conditions and episodes of crystalluria.