Crystal Interactions in Renal Stone Disease

肾结石是一种严重的健康问题，与巨大的疼痛、痛苦和经济成本有关。到70岁时，5%至15%的人口将出现尿路结石的症状发作，其中至少50%的人将患有复发性结石疾病。这笔赠款的重点是将尿晶附着在受损的肾乳头状尖端上皮上。我们的研究是基于这样一个假设，即晶体附着于乳头状上皮需要细胞/组织损伤，包括细胞浆、脂质不对称和/或细胞极性的丧失。将采用两种特定的内髓集合管(IMCD)细胞损伤模型。(I)质膜脂质不对称性的丧失，导致磷脂酰丝氨酸从细胞膜的内叶到外叶的呈现，以及(Ii)由于细胞内紧密连接断裂而导致的细胞极性的丧失，导致质膜基侧和顶膜成分混合到改变的管腔细胞表面。在这两种模型中，损伤导致顶膜成分/结构改变，更重要的是将非晶体附着细胞转变为确实附着晶体的细胞。拟议的研究分为三个特定的目标，以检验三个特定的假设。他们将利用已建立的细胞培养和隔离的灌流小管系统，以及高草酸尿石症动物模型。研究将仅限于人类尿路结石最常见的四种结晶成分，即一水草酸钙(COM)和二水草酸钙(COD)、碱性磷酸钙(AP)和尿酸(UA)晶体。具体目标是：特定目标I：在受损的乳头状集合管细胞中，确定尿路环境对改变的质膜表面分子中晶体附着的分子性质的影响。特定目的II：确定两个特定的肾单位节段对明确的损伤和随后的晶体附着的相对敏感性。具体目的III：在动物模型中确定轻度慢性高草酸尿症是否会导致局限性肾单位细胞损伤，这种损伤先于过饱和条件下的晶体附着和结晶尿发作。

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.