Departments of Pathology and.
Genome Sciences, University of Washington, Seattle, Washington.
J Am Soc Nephrol. 2018 Jan;29(1):231-239. doi: 10.1681/ASN.2017050566. Epub 2017 Nov 2.
Fibrillary GN is a rare form of GN of uncertain pathogenesis that is characterized by the glomerular accumulation of randomly arranged, nonbranching fibrils (12-24 nm) composed of Ig and complement proteins. In this study, we used mass spectrometry to comprehensively define the glomerular proteome in fibrillary GN compared with that in controls and nonfibrillary GN renal diseases. We isolated glomeruli from formalin-fixed and paraffin-embedded biopsy specimens using laser capture microdissection and analyzed them with liquid chromatography and data-dependent tandem mass spectrometry. These studies identified DnaJ homolog subfamily B member 9 (DNAJB9) as a highly sampled protein detected only in fibrillary GN cases. The glomerular proteome of fibrillary GN cases also contained IgG1 as the dominant Ig and proteins of the classic complement pathway. In fibrillary GN specimens only, immunofluorescence and immunohistochemistry with an anti-DNAJB9 antibody showed strong and specific staining of the glomerular tufts in a distribution that mimicked that of the immune deposits. Our results identify DNAJB9 as a putative autoantigen in fibrillary GN and suggest IgG1 and classic complement effector pathways as likely mediators of the destructive glomerular injury in this disease.
纤维状 GN 是一种罕见的 GN 形式，其发病机制尚不确定，其特征是肾小球内随机排列的无分支纤维（12-24nm）的积累，这些纤维由 Ig 和补体蛋白组成。在这项研究中，我们使用质谱法对纤维状 GN 与对照和非纤维状 GN 肾脏疾病的肾小球蛋白质组进行了全面定义。我们使用激光捕获显微切割从福尔马林固定和石蜡包埋的活检标本中分离肾小球，并使用液相色谱和数据依赖串联质谱法对其进行分析。这些研究鉴定出 DnaJ 同源亚家族 B 成员 9（DNAJB9）为一种高度采样蛋白，仅在纤维状 GN 病例中检测到。纤维状 GN 病例的肾小球蛋白质组还包含 IgG1 作为主要的 Ig 和经典补体途径的蛋白。在纤维状 GN 标本中，用抗 DNAJB9 抗体进行免疫荧光和免疫组化染色显示，肾小球簇的强烈和特异性染色分布类似于免疫沉积物的分布。我们的结果将 DNAJB9 鉴定为纤维状 GN 中的一个假定自身抗原，并表明 IgG1 和经典补体效应途径可能是该疾病中破坏性肾小球损伤的介导物。
