IgA1 glycosylation and receptor interactions in IgA nephropathy

描述（由申请人提供）：伊加肾病（IgAN）是肾小球肾炎的最常见形式，是肾脏的一种炎性疾病。IgAN的特征在于IgA 1抗体在肾脏的肾小球系膜中的沉积，随后是炎性免疫细胞的浸润和最终的肾功能丧失。IgA 1抗体在大部分IgAN患者中显示改变的糖基化和聚合状态。这些改变已被认为在改变IgA 1和IgA特异性受体，特别是FcalphaRI（CD 89）和转铁蛋白受体（TfR）之间的相互作用中发挥作用，尽管已经报道了相互矛盾的数据。这项研究工作的长期目标是确定导致IgA 1沉积在系膜中的精确分子事件。中心假设是，IgA 1糖基化和聚合的修饰导致对关键IgA结合受体（特别是FcalphaRI和TfR）的亲和力增加。这些异常的相互作用被认为直接导致IgA 1在肾系膜中的沉积和随后的炎症反应。该提案的具体目的包括：1）使用具有确定的糖基化状态的重组lgA 1，表征lgA 1糖基化和聚合对其与FcalphaRI和TfR的相互作用的影响; 2）表征从健康和IgAN患者血清中纯化的lgA 1的受体相互作用，并将受体亲和力与lgA 1糖基化和聚合状态相关联;和3）测定FcalphaRI N-糖基化对其与IgA 1和TfR相互作用的贡献。将通过表面等离子体共振和分析性超离心进行与IgA 1、FcalphaRI和TfR的结合研究。通过凝集素亲和力测定沿着通过傅立叶变换-离子回旋共振质谱法对感兴趣的样品进行彻底分析来表征IgA 1糖基化。这项研究将有助于确定伊加肾病（IgAN）的分子基础，IgA肾病是一种影响美国约10万患者的肾脏疾病。IgAN是终末期肾病的主要原因，每年花费180亿美元用于医疗保健。了解IgAN潜在的分子相互作用将是为这种昂贵且使人衰弱的疾病开发治疗方法的第一步。

DESCRIPTION (provided by applicant): IgA nephropathy (IgAN) is the most common form of glomerulonephritis, an inflammatory disease of the kidney. IgAN is characterized by deposition of lgA1 antibodies in the glomerular mesangium of the kidney, followed by infiltration of inflammatory immune cells and eventual loss of kidney function. lgA1 antibodies show altered glycosylation and polymerization states in a large percentage of IgAN patients. These alterations have been suggested to play a role in modifying the interactions between lgA1 and IgA-specific receptors, particularly, FcalphaRI (CD89) and transferrin receptor (TfR), although conflicting data have been reported. The long-term goal of this research effort is to ascertain the precise molecular events that lead to lgA1 deposition in the mesangium. The central hypothesis is that modifications in lgA1 glycosylation and polymerization lead to increased affinity for critical IgA-binding receptors (specifically, FcalphaRI and TfR). These aberrant interactions are proposed to lead directly to deposition of lgA1 in the kidney mesangium and the ensuing inflammatory response. Specific Aims for this proposal include: 1) Characterize the effects of lgA1 glycosylation and polymerization on its interaction with FcalphaRI and TfR, using recombinant lgA1 with defined glycosylation states; 2) Characterize the receptor interactions of lgA1 purified from serum of healthy and IgAN patients and correlate the receptor affinity with lgA1 glycosylation and polymerization state; and 3) Determine the contribution of FcalphaRI N-glycosylation to its interaction with lgA1 and TfR. Binding studies with lgA1, FcalphaRI, and TfR will be carried out by surface plasmon resonance and analytical ultracentrifugation. lgA1 glycosylation will be characterized by lectin affinity assays along with thorough analysis of samples of interest by Fourier transform-ion cyclotron resonance mass spectrometry. This research will help determine the molecular basis for IgA nephropathy (IgAN), a kidney disease affecting approximately 100,000 patients in the US. IgAN is a primary cause of end-stage renal disease, which costs $18 billion per year in medical care. Understanding the molecular interactions underlying IgAN will be the first step towards developing treatments for this costly and debilitating disease.