Few studies have examined gene-expression changes occurring in the glomeruli of immunoglobulin A nephropathy (IgAN) using a sensitive transcriptomic profiling method such as RNA sequencing (RNA-seq). We collected glomeruli from biopsy specimens from IgAN patients with relatively preserved kidney function (eGFR ≥ 60 mL/min/1.73 m² and urine protein-to-creatinine ratio < 3 g/g) and from normal kidney cortices by hand microdissection and performed RNA-seq. Differentially expressed genes (DEG) were identified, and gene-ontology term annotation and pathway analysis were performed. Immunohistochemical labeling and primary mesangial cell cultures were performed to confirm the findings of RNA-seq analysis. Fourteen IgAN patients and ten controls were included in this study. Glomerulus-specific genes were highly abundant. Principal component analysis showed clear separation between the IgAN and control groups. There were 2,497 DEGs, of which 1,380 were upregulated and 1,117 were downregulated (false discovery rate < 0.01). The enriched gene ontology terms included motility/migration, protein/vesicle transport, and immune system, and the kinase binding was the molecular function overrepresented in IgAN. B cell signaling, chemokine signal transduction, and FcγR-mediated phagocytosis were the canonical pathways overrepresented. In vitro studies confirmed that spleen tyrosine kinase (SYK), reported as upregulated in the IgAN transcriptome, was also upregulated in the glomeruli from an independent set of IgAN patients and that treatment with patient-derived IgA1 increased the expression of SYK in mesangial cells. In conclusion, the transcriptomic profiling of IgAN glomerulus provide insights for intraglomerular pathophysiology of IgAN before reaching profound kidney dysfunction. SYK may have a pathogenetic role in IgAN.

中文翻译：

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显微解剖的肾小球的RNA序列分析确定了人类IgA肾病的潜在生物标志物。

很少有研究使用诸如RNA测序（RNA-seq）之类的敏感转录组分析方法来检查免疫球蛋白A肾病（IgAN）肾小球中发生的基因表达变化。我们从肾功能相对保留（eGFR≥60 mL / min / 1.73 m ^2的IgAN患者的活检标本中收集肾小球和尿蛋白与肌酐之比<3 g / g），并通过手显微解剖从正常肾皮质中提取RNA，并进行RNA序列测定。鉴定差异表达基因（DEG），并进行基因本体术语注释和途径分析。进行了免疫组织化学标记和原代肾小球膜细胞培养，以证实RNA-seq分析的结果。这项研究包括14名IgAN患者和10名对照。肾小球特异性基因高度丰富。主成分分析表明，IgAN和对照组之间存在明显的分离。有2497个DEG，其中上调了1380个，下调了1117个（错误发现率<0.01）。丰富的基因本体术语包括运动性/迁移，蛋白质/囊泡运输和免疫系统，激酶结合是IgAN中分子功能过高的表现。B细胞信号转导，趋化因子信号转导和FcγR介导的吞噬作用是代表性的典型途径。体外研究证实，在独立的一组IgAN患者的肾小球中，脾脏酪氨酸激酶（SYK）在IgAN转录组中被上调，并且在肾小球中也被上调，并且用患者衍生的IgA1进行的治疗增加了系膜细胞中SYK的表达。总之，在达到严重的肾功能不全之前，IgAN肾小球的转录组谱分析为IgAN的肾小球内病理生理学提供了见识。SYK可能在IgAN中具有致病作用。体外研究证实，在独立的一组IgAN患者的肾小球中，脾脏酪氨酸激酶（SYK）在IgAN转录组中被上调，并且在肾小球中也被上调，并且用患者衍生的IgA1进行的治疗增加了系膜细胞中SYK的表达。总之，在达到严重的肾功能不全之前，IgAN肾小球的转录组谱分析为IgAN的肾小球内病理生理学提供了见识。SYK可能在IgAN中具有致病作用。体外研究证实，在独立的一组IgAN患者的肾小球中，脾脏酪氨酸激酶（SYK）在IgAN转录组中被上调，并且在肾小球中也被上调，并且用患者衍生的IgA1进行的治疗增加了系膜细胞中SYK的表达。总之，在达到严重的肾功能不全之前，IgAN肾小球的转录组谱分析为IgAN的肾小球内病理生理学提供了见识。SYK可能在IgAN中具有致病作用。IgAN肾小球的转录组分析为深入了解肾功能不全提供了IgAN肾小球内病理生理学的见解。SYK可能在IgAN中具有致病作用。IgAN肾小球的转录组分析为深入了解肾功能不全提供了IgAN肾小球内病理生理学的见解。SYK可能在IgAN中具有致病作用。