Integrated miRNA-mRNA analysis reveals critical miRNAs and targets in the diet-induced obesity-related glomerulopathy

Background:The objective of this study was to investigate obesity-related glomerulopathy (ORG) at a cellular, structural and transcriptomic level. Methods:Thirty Wistar rats were randomized into two groups: control rats(n=15), which were fed a standard diet(SD) and study rats(n=15), which were fed a high-fat diet (HFD). After 10 weeks, weight, parameters of kidney function, renal histological features, transcriptomic changes, miRNA and mRNA isolation were compared. Results:HFD gained more weight(55.8%) than SD(29.2%), p<0.001. Albuminuria was also significantly higher in HFD(10,384.04 ng/ml) compared with SD(5,845.45 ng/ml), p<0.001. HFD showed typical lesions of early stages of ORG, with a predominance of mesangial matrix increase (MMI) and podocyte hypertrophy (PH). All histologic lesions correlated with genes differentially expressed (DE) in kidneys of HFD group and PH, also correlated with specific miRNAs DE in the urine of HFD. The functional analysis showed 4 miRNAs DE in the kidneys of HFD group that negatively regulates PTEN gene, which promotes podocyte endocytosis of lipids in ORG. The electronic microscope confirmed the spaces of lipid vacuoles in the podocytes of HFD. Between those 4 miRNAs DE, miR-205 was also found to be upregulated in the urine of HFD group. Conclusions: Wistar rats fed a HFD developed early-stages of ORG, with a specific targetome of miRNAs and gene expression. The upregulation of miR-205 in kidney and its isolation in urine is associated with lipid endocytosis of podocytes, which could become a plausible biomarker of early-stages of ORG and open new avenues for future therapeutics research. Translational Statement: The findings of the basic research in this study can be replicated in human models of obesity. The results of the study on miRNA in humans may contribute to improving the understanding of the pathophysiology of obesity-related glomerulopathy, aiding in the search for early biomarkers, and exploring new therapeutic targets. Keywords: MicroRNA, Biomarker, targetome, obesity-related glomerulopathy, mesangial matrix increase, podocyte hypertrophy, Wistar rats背景：本研究旨在从细胞、结构与转录组维度，深入探究肥胖相关性肾小球病（obesity-related glomerulopathy, ORG）的相关特征。 方法：将30只Wistar大鼠随机分为两组：对照组大鼠（n=15）给予标准饮食（standard diet, SD），造模组大鼠（n=15）给予高脂饮食（high-fat diet, HFD）。造模10周后，对两组大鼠的体重、肾功能指标、肾脏组织学特征、转录组变化以及微小核糖核酸（microRNA, miRNA）和信使核糖核酸（messenger RNA, mRNA）的分离情况进行比较分析。 结果：高脂饮食组大鼠体重增幅达55.8%，显著高于标准饮食组的29.2%（p<0.001）。高脂饮食组的白蛋白尿水平同样显著升高，为10384.04 ng/ml，而标准饮食组为5845.45 ng/ml（p<0.001）。高脂饮食组大鼠出现了肥胖相关性肾小球病早期阶段的典型病理损伤，以系膜基质增生（mesangial matrix increase, MMI）和足细胞肥大（podocyte hypertrophy, PH）为主要表现。所有组织学损伤均与高脂饮食组肾脏组织中的差异表达基因（differentially expressed, DE）相关，且足细胞肥大亦与高脂饮食组尿液中特异性差异表达的微小核糖核酸相关。功能分析显示，高脂饮食组肾脏组织中4种差异表达的微小核糖核酸可负向调控PTEN基因，而该基因可促进肥胖相关性肾小球病中足细胞的脂质内吞作用。电子显微镜证实，高脂饮食组大鼠的足细胞内存在脂质空泡结构。在上述4种差异表达的微小核糖核酸中，miR-205在高脂饮食组大鼠尿液中也呈现上调表达。 结论：给予高脂饮食的Wistar大鼠可出现肥胖相关性肾小球病早期病变，其具备特异性的微小核糖核酸靶标组与基因表达谱。肾脏组织中miR-205的上调表达及其在尿液中的检出，与足细胞脂质内吞作用密切相关，这有望成为肥胖相关性肾小球病早期阶段的潜在生物标志物，同时为未来的治疗研究开辟新方向。 转化性声明：本研究的基础研究结果可在人类肥胖模型中得到验证。针对人类微小核糖核酸的研究结果，有助于加深我们对肥胖相关性肾小球病病理生理学机制的理解，助力早期生物标志物的筛选，并为新型治疗靶点的探索提供依据。 关键词：微小核糖核酸（MicroRNA）、生物标志物、靶标组、肥胖相关性肾小球病、系膜基质增生、足细胞肥大、Wistar大鼠