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 Overall design: To investigate the interactome of miRNAs, their targetome, and the presence of obesity-related renal disease, we established a non-genetically modified animal model of obesity. Thirty male Wistar rats were included in the study and randomized into two groups: 15 rats fed a standard diet (control group) and 15 rats fed a high-fat diet (experimental group) for 10 weeks. Total RNA and small RNA were extracted from rat kidneys, while small RNA was also extracted from urine. Comparative gene expression profiling analysis of RNA-seq and small RNA data was performed.