The single-cell transcriptomic landscape of early human diabetic nephropathy

Diabetic nephropathy is characterized by damage to both the glomerulus and tubulointerstitium, but relatively little is known about accompanying cell-specific changes in gene expression. We performed unbiased single nucleus RNA sequencing (snRNAseq) on cryopreserved human diabetic kidney samples to generate 23,980 single nucleus transcriptomes from three control and three early diabetic nephropathy samples. All major cell types of the kidney were represented in the final dataset. Side by side comparison demonstrated cell-type-specific changes in gene expression that are important for ion transport, angiogenesis, and immune cell activation. In particular, we show that the diabetic thick ascending limb, late distal convoluted tubule, and principal cells all adopt a gene expression signature consistent with increased potassium secretion, including alterations in Na-K+-ATPase, WNK1, mineralocorticoid receptor and NEDD4L expression, as well as decreased paracellular calcium and magnesium reabsorption. We also identify strong angiogenic signatures in glomerular cell types, proximal convoluted tubule, distal convoluted tubule and principal cells. Taken together, these results suggest that increased potassium secretion and angiogenic signaling represent early kidney responses in human diabetic nephropathy.

糖尿病肾病（Diabetic nephropathy）以肾小球（glomerulus）与肾小管间质（tubulointerstitium）损伤为特征，但目前对伴随的细胞特异性基因表达变化的认知仍相对匮乏。本研究对冻存的人类糖尿病肾脏样本开展无偏倚单细胞核RNA测序（single nucleus RNA sequencing, snRNAseq），从3例对照样本与3例早期糖尿病肾病样本中获取23980个单细胞核转录组。最终数据集涵盖肾脏所有主要细胞类型。通过平行对照分析，本研究揭示了与离子转运、血管生成及免疫细胞激活密切相关的细胞特异性基因表达变化。具体而言，本研究发现糖尿病状态下的髓袢升支粗段（thick ascending limb）、远曲小管晚期（late distal convoluted tubule）及主细胞（principal cells）均呈现出与钾分泌增加相符的基因表达特征，包括Na⁺-K⁺-ATP酶（Na-K+-ATPase）、WNK1、盐皮质激素受体（mineralocorticoid receptor）及NEDD4L的表达改变，同时伴随细胞旁钙、镁重吸收功能降低。本研究还在肾小球细胞群、近端曲小管（proximal convoluted tubule）、远端曲小管（distal convoluted tubule）及主细胞中鉴定出显著的血管生成特征。综上，上述结果提示，钾分泌增加与血管生成信号通路激活是人类糖尿病肾病早期的肾脏应答反应。