Abnormal cytokine response and autoantigen production in IgA-producing subpopulations in IgA nephropathy

摘要 IgA肾病(IgAN)是最常见的原发性肾小球肾炎。它会导致终末期肾病 (ESKD)在40-50%的患者中。IGAN患者通常表现为肉眼血尿，通常与 上呼吸道感染。粘膜感染时可见肾损伤的加重 炎症表明这两者之间存在联系。在IgAN患者的活检中，定义 本病的特征是聚合性IgA1的沉积，通常伴有免疫球蛋白和补体C3的共同作用。 押金。对沉积的IgA1的分析表明，与半乳糖缺乏的IgA1(Gd-IgA1)相比，Gd-IgA1具有富集性 循环中的IgA1。此外，共沉积的免疫球蛋白对Gd-IgA1具有特异性。这似乎是免疫的 复杂的沉积，这也存在于患者的循环中。血清Gd-IgA1和抗Gd-IgA1- 免疫球蛋白自身抗体在IgAN患者中升高，与疾病进展有关，并可在 在循环中变得复杂。这种循环自身抗原(Gd-IgA1)通常以聚合物形式存在，它 是粘膜区域独有的。这表明产生IgA1的细胞的一部分可能从 粘膜区，或在其他地方形成异常的产生IgA1的细胞。初步观察表明，粘膜 与IgAN患者一过性血尿相关的感染导致了这一论断 刺激可增加循环中含Gd-IgA1的免疫复合体，导致肾脏损伤。我们 最近发表了IL-6对来自IgAN患者的EBV永生化的产生IgA1的细胞的刺激，但不是 对照组，由于STAT3激活增强和延长，Gd-IgA1的产量优先增加。在……里面 此外，我们实验室使用永生化IgA产生的单细胞转录组图谱的初步数据 来自IgAN患者和健康对照组的细胞显示有多种产生IgA1的细胞群 对细胞因子刺激的不同反应。这些观察结果导致了我们的假设，即增强了Gd- IgA1的产生是产生IgA1的细胞亚群异常细胞因子反应的结果。在目标1中， 我们将测试这一假设，即细胞因子暴露对IgA1产生细胞亚群有不同的影响 来自IgAN患者的EB病毒永生化的产生IgA1的细胞与健康和疾病对照。在目标2中，我们将 检验对细胞因子刺激有不同反应的产生IgA1的细胞亚群的假设 优先产生Gd-IgA1。这两个目标的结合将有助于识别特定的IgA1- 产生有助于自身抗原产生的细胞亚群。这些研究将使测试小说成为可能 研究假设并产生新的初步数据，以制定具有竞争力的R01提案。

Abstract IgA nephropathy (IgAN) is the most common primary glomerulonephritis. It leads to end-stage kidney disease (ESKD) in 40-50% of patients. IgAN patients often exhibit macroscopic hematuria, commonly associated with upper-respiratory tract infections. This exacerbation of kidney injury seen during episodes of mucosal infection and inflammation suggests a connection between the two. In biopsies of IgAN patients, the defining characteristic of this disease is the deposits of polymeric IgA1, typically with IgG and complement C3 co- deposits. Analysis of the deposited IgA1 revealed enrichment for galactose-deficient IgA1 (Gd-IgA1) compared to circulatory IgA1. In addition, the co-deposited IgG is specific for Gd-IgA1. This appears to be immune complex deposition, which is also found in circulation of patients. Serum levels of Gd-IgA1 and anti-Gd-IgA1- IgG autoantibodies are elevated in IgAN patients, associate with disease progression, and can be found complexed in circulation. This circulatory autoantigen (Gd-IgA1) is typically found in the polymeric form, which is unique to the mucosal region. This suggests that a subset of IgA1-producing cells could be migrating from mucosal regions, or there is abnormal IgA1-producing cells formed elsewhere. Initial observations that mucosal infections associated with transient hematuria in IgAN patients led to the thesis that pro-inflammatory stimulation could increase circulatory Gd-IgA1-containing immune complexes, causing renal injury. We recently published that IL-6 stimulation in EBV-immortalized IgA1-producing cells from IgAN patients, but not controls, preferentially increased Gd-IgA1 production due to an enhanced and prolonged STAT3 activation. In addition, preliminary data in our lab from single-cell transcriptome profiling using immortalized IgA-producing cells from IgAN patients and healthy controls revealed multiple populations of IgA1-producing cells that have differential responses to cytokine stimulation. These observations led to our hypothesis that enhanced Gd- IgA1 production is a result of abnormal cytokine response in a subset of IgA1-producing cells. In Aim 1, we will test the hypothesis that cytokine exposure has differential effects on subsets of IgA1-producing cells in EBV- immortalized IgA1-producing cells from IgAN patients vs. healthy and disease controls. In Aim 2, we will test the hypothesis that subsets of IgA1-producing cells that have differential responses to cytokine stimulation are preferentially producing Gd-IgA1. The combination of these two aims will help identify the specific IgA1- producing cell subsets that contribute to autoantigen production. These studies will enable testing of novel research hypotheses and yield new preliminary data towards a competitive R01 proposal.