RNA Sequencing reveals induction of specific renal inflammatory pathways in a rat model of malignant hypertension

In malignant hypertension, far more severe kidney injury occurs than in the “benign” form of the disease. The role of high blood pressure and the renin-angiotensin-aldosterone system are well recognized, but the development of malignant nephrosclerosis remains incompletely understood. Using the rat model of two-kidney, one-clip renovascular hypertension in which some but not all animals develop malignant nephrosclerosis, we performed an unbiased analysis of genes by RNA-sequencing to identify transcriptional changes in the kidney specific for malignant nephrosclerosis. Differential gene expression was assessed in three groups: malignant hypertension (MH), non-malignant hypertension (NMH) and normotensive, sham operated controls (sham). To distinguish MH from NMH, we considered two factors: weight loss and typical renovascular lesions. Mean blood pressure measured intraarterially was elevated to a similar degree in MH (220.0±6.5 mmHg) and NMH (192.0±6.4 mmHg) compared to controls (119.5±1.7 mmHg, p<0.05). 886 genes were exclusively regulated in MH only. Principal component analysis revealed a separated clustering of the three groups. The data pointed to an upregulation of many inflammatory mechanisms in MH including pathways, which did previously attract relatively little attention in the setting of hypertensive nephrosclerosis: Transcripts from all three complement activation pathways were upregulated in MH compared to NMH but not in NMH compared with controls; immunohistochemistry confirmed complement deposition in MH exclusively. The expression of chemokines attracting neutrophil granulocytes (CXCL6) as well as actual granulocyte infiltration were increased only in MH rats. The data suggest that these pathways may contribute to the most severe forms of hypertensive nephrosclerosis. Analysis of gene expression in the kidney in a animal model of renovascular hypertension elucidating the pathogenic background of malignant hypertension using RNA-Seq

与该疾病的“良性”亚型相比，恶性高血压会引发更为严重的肾脏损伤。高血压与肾素-血管紧张素-醛固酮系统（renin-angiotensin-aldosterone system）的致病作用已得到广泛认可，但恶性肾硬化（malignant nephrosclerosis）的发病机制仍未完全阐明。本研究采用两肾一夹型肾血管性高血压大鼠模型——该模型中仅部分动物会出现恶性肾硬化，通过RNA测序（RNA-sequencing）对基因进行无偏分析，以鉴定恶性肾硬化特异性的肾脏转录组变化。我们对三组样本进行了差异基因表达分析：恶性高血压组（malignant hypertension, MH）、非恶性高血压组（non-malignant hypertension, NMH）以及血压正常的假手术对照组（normotensive, sham operated controls, sham）。为区分MH与NMH，本研究采用体重下降与典型肾血管病变两项评判指标。经动脉内测压得到的平均血压结果显示：与对照组（119.5±1.7 mmHg，p<0.05）相比，MH组（220.0±6.5 mmHg）与NMH组（192.0±6.4 mmHg）的血压均显著升高，且两组血压升高幅度相近。共有886个基因仅在MH组中发生特异性表达调控。主成分分析（Principal component analysis, PCA）结果显示，三组样本呈现出清晰的聚类分离。研究数据表明，MH组中多种炎症通路出现上调，其中包括此前在高血压肾硬化研究中关注度相对较低的通路：与NMH组相比，MH组的三条补体激活通路的转录本均出现上调，而NMH组与对照组相比则无此变化；免疫组化实验证实，补体沉积仅出现于MH组大鼠体内。募集中性粒细胞的趋化因子（CXCL6）的表达水平以及实际的粒细胞浸润情况，也仅在MH组大鼠中出现升高。上述数据提示，这些通路可能参与了最为严重的高血压肾硬化亚型的发病过程。本研究通过RNA测序对肾血管性高血压大鼠模型的肾脏基因表达进行分析，阐明了恶性高血压的发病机制背景。