Macrophage Infiltration of Renal Tissue via beta-3 Integrins and Agrin

描述（申请人提供）：肾小球肾炎最常见的是一种自身免疫诱导的炎症事件，其中巨噬细胞浸润肾脏导致纤维化导致肾功能丧失。我们实验室的长期目标是确定控制巨噬细胞粘附从而调节炎症反应的分子开关。我们之前发现了23个整合素粘附受体的酪氨酸磷酸化是一个这样的开关，并证明了23磷酸化对于巨噬细胞粘附某些配体是必要的。阻断23磷酸化导致肌动蛋白细胞骨架无法组织成应力纤维，从而导致粘附丧失。在这个应用中，我们提出的证据表明，巨噬细胞进入肾组织需要这种独特的机制。我们假设巨噬细胞通过肾基底膜是由蛋白聚糖agrin和磷酸化的23整合素之间的相互作用介导的。在本应用中，我们将评估23个整合素及其磷酸化在实验性肾小球肾炎期间向肾组织迁移中的作用。我们将通过体外迁移研究确定肾基底膜中的agrin是否调节巨噬细胞的浸润。我们将通过活体巨噬细胞的TIRF显微镜来描述巨噬细胞足突粘连和假足的产生，这是迁移到三维组织所必需的。我们将从生化角度确定磷酸化23的信号，该信号控制巨噬细胞假足和足体中肌动蛋白细胞骨架重组。确定器官特异性巨噬细胞免疫运输过程中使用的机制可以为治疗干预提供新的靶点，并补充全球免疫抑制疗法。公共卫生相关性：我们的实验室发现了一种白细胞粘附组织的新机制。这项研究计划将确定一种被称为23整合素的特殊粘附分子是否会导致肾小球肾炎（肾脏炎症），这种粘附分子存在于白细胞的一个亚群中。了解肾小球肾炎的发病机制可以为药物开发提供新的靶点，以减少疾病的进展。

DESCRIPTION (provided by applicant): Glomerulonephritis is most commonly an autoimmune-induced inflammatory event wherein infiltration of the kidney by macrophages results in loss of renal function due to fibrosis. The long-term goal of our laboratory is to identify the molecular switches that govern macrophage adhesion and thus regulate the inflammatory response. We previously identified tyrosine phosphorylation of 23 integrin adhesion receptors as one such switch and have demonstrated that 23 phosphorylation is necessary for macrophage adhesion to some ligands. Blockade of 23 phosphorylation results in loss of adhesion due to a failure of the actin cytoskeleton to organize into stress fibers. In this application we present evidence that this unique mechanism is required for macrophage entry into renal tissues. We hypothesize that macrophage passage through renal basement membrane is mediated by an interaction between the proteoglycan agrin and phosphorylated 23 integrins. In this application we will assess the role of 23 integrins and their phosphorylation in migration to renal tissues during experimental glomerulonephritis. We will determine whether agrin in renal basement membrane regulates macrophage infiltration by in vitro transmigration studies. We will characterize the production of macrophage podosomal adhesions and pseudopods that are required for migration into three-dimensional tissues by TIRF microscopy of living macrophages. We will biochemically determine the signaling from phosphorylated 23 that controls actin cytoskeletal reorganization in the macrophage pseudopod and podosome. Identification of mechanisms used during organ-specific macrophage immune trafficking can provide novel targets for therapeutic intervention and complement global immune-suppressive therapies. PUBLIC HEALTH RELEVANCE: r laboratory has identified a new mechanism of white blood cell adhesion to tissues. This research proposal will determine whether a particular adhesion molecule called 23 integrin, found on a subset of white blood cells, contributes to glomerulonephritis (inflammation of the kidneys). Understanding the mechanism of glomerulonephritis can provide new targets for drugs to reduce the progression of this disease.