MicroRNA Expression Profiling in Diabetic Kidney Disease

microRNAs in kidney diseases: Regulation, therapeutics, and biomarker potential

MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in regulating gene expression by inhibiting the translation of their specific target messenger RNAs. To date, numerous studies have demonstrated changes in the expression of miRNAs in the kidneys throughout the progression of both acute kidney injury (AKI) and chronic kidney disease (CKD) in both human patients and experimental models. The role of specific microRNAs in the pathogenesis of kidney diseases has also been demonstrated. Further studies have elucidated the regulation of these microRNAs in diseased kidneys. Besides, certain miRNAs are detected in plasma and/or urine in kidney diseases and are potential diagnostic biomarkers. In this review, we provide an overview of recent developments in our understanding of how miRNAs contribute to kidney diseases. We also explore the potential of miRNAs as both biomarkers and therapeutic targets for these conditions, and highlight future research directions.

Panel miRNAs are potential diagnostic markers for chronic kidney diseases: a systematic review and meta-analysis

BACKGROUND

Accurate detection of kidney damage is key to preventing renal failure, and identifying biomarkers is essential for this purpose. We aimed to assess the accuracy of miRNAs as diagnostic tools for chronic kidney disease (CKD).

METHODS

We thoroughly searched five databases (MEDLINE, Web of Science, Embase, Scopus, and CENTRAL) and performed a meta-analysis using R software. We assessed the overall diagnostic potential using the pooled area under the curve (pAUC), sensitivity (SEN), and specificity (SPE) values and the risk of bias by using the QUADAS-2 tool. The study protocol was registered on PROSPERO (CRD42021282785).

RESULTS

We analyzed data from 8351 CKD patients, 2989 healthy individuals, and 4331 people with chronic diseases. Among the single miRNAs, the pooled SEN was 0.82, and the SPE was 0.81 for diabetic nephropathy (DN) vs. diabetes mellitus (DM). The SEN and SPE were 0.91 and 0.89 for DN and healthy controls, respectively. miR-192 was the most frequently reported miRNA in DN patients, with a pAUC of 0.91 and SEN and SPE of 0.89 and 0.89, respectively, compared to those in healthy controls. The panel of miRNAs outperformed the single miRNAs (pAUC of 0.86 vs. 0.79, p < 0.05). The SEN and SPE of the panel miRNAs were 0.89 and 0.73, respectively, for DN vs. DM. In the lupus nephritis (LN) vs. systemic lupus erythematosus (SLE) cohorts, the SEN and SPE were 0.84 and 0.81, respectively. Urinary miRNAs tended to be more effective than blood miRNAs (p = 0.06).

CONCLUSION

MiRNAs show promise as effective diagnostic markers for CKD. The detection of miRNAs in urine and the use of a panel of miRNAs allows more accurate diagnosis.

A Systematic Review and Meta-Analysis of microRNA Profiling Studies in Chronic Kidney Diseases

Chronic kidney disease (CKD) represents an increasing health burden. Evidence suggests the importance of miRNA in diagnosing CKD, yet the reports are inconsistent. This study aimed to determine novel miRNA biomarkers and potential therapeutic targets from hypothesis-free miRNA profiling studies in human and murine CKDs. Comprehensive literature searches were conducted on five databases. Subgroup analyses of kidney diseases, sample types, disease stages, and species were conducted. A total of 38 human and 12 murine eligible studies were analyzed using Robust Rank Aggregation (RRA) and vote-counting analyses. Gene set enrichment analyses of miRNA signatures in each kidney disease were conducted using DIANA-miRPath v4.0 and MIENTURNET. As a result, top target genes, Gene Ontology terms, the interaction network between miRNA and target genes, and molecular pathways in each kidney disease were identified. According to vote-counting analysis, 145 miRNAs were dysregulated in human kidney diseases, and 32 were dysregulated in murine CKD models. By RRA, miR-26a-5p was significantly reduced in the kidney tissue of Lupus nephritis (LN), while miR-107 was decreased in LN patients' blood samples. In both species, epithelial-mesenchymal transition, Notch, mTOR signaling, apoptosis, G2/M checkpoint, and hypoxia were the most enriched pathways. These miRNA signatures and their target genes must be validated in large patient cohort studies.

Functions and targets of miRNAs in pharmacological and toxicological effects of major components of Tripterygium wilfordii Hook F

Tripterygium wilfordii Hook F (TwHF) has a long history of use as a traditional Chinese medicine and has been widely administered to treat various inflammatory and autoimmune diseases. MicroRNAs (miRNAs) are endogenous, short, non-coding RNAs that regulate gene expression post-transcriptionally. They participate in the efficacies and even toxicities of the components of TwHF, rendering miRNAs an appealing therapeutic strategy. This review summarizes the recent literature related to the roles and mechanisms of miRNAs in the pharmacological and toxicological effects of main components of TwHF, focusing on two active compounds, triptolide (TP) and celastrol (CEL). Additionally, the prospects for the "You Gu Wu Yun" theory regarding TwHF nephrotoxicity are presented.

The role of ncRNAs-mediated pyroptosis in diabetes and its vascular complications

Over the past decade, the prevalence of diabetes has increased significantly worldwide, leading to an increase in vascular complications of diabetes (VCD), such as diabetic cardiomyopathy (DCM), diabetic nephropathy (DN), and diabetic retinopathy (DR). Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), long Noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), play a key role in cellular processes, including the pathophysiology of diabetes and VCD via pyroptosis. ncRNAs (e.g., miR-17, lnc-MEG3, and lnc-KCNQ1OT1) can regulate pyroptosis in pancreatic β cells. Some ncRNAs are involved in VCD progression. For example, miR-21, lnc-KCNQ1OT1, lnc-GAS5, and lnc-MALAT1 were reported in DN and DCM, and lnc-MIAT was identified in DCM and DR. Herein, this review aimed to summarize recent research findings related to ncRNAs-mediated pyroptosis at the onset and progression of diabetes and VCD.

Advances in Research Related to MicroRNA for Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe microvascular complication of diabetes and is one of the primary causes of blindness in the working-age population in Europe and the United States. At present, no cure is available for DR, but early detection and timely intervention can prevent the rapid progression of the disease. Several treatments for DR are known, primarily ophthalmic treatment based on glycemia, blood pressure, and lipid control, which includes laser photocoagulation, glucocorticoids, vitrectomy, and antivascular endothelial growth factor (anti-VEGF) medications. Despite the clinical efficacy of the aforementioned therapies, none of them can entirely shorten the clinical course of DR or reverse retinopathy. MicroRNAs (miRNAs) are vital regulators of gene expression and participate in cell growth, differentiation, development, and apoptosis. MicroRNAs have been shown to play a significant role in DR, particularly in the molecular mechanisms of inflammation, oxidative stress, and neurodegeneration. The aim of this review is to systematically summarize the signaling pathways and molecular mechanisms of miRNAs involved in the occurrence and development of DR, mainly from the pathogenesis of oxidative stress, inflammation, and neovascularization. Meanwhile, this article also discusses the research progress and application of miRNA-specific therapies for DR.

Non-Coding RNAs in Kidney Stones

Nephrolithiasis is a major public health concern associated with high morbidity and recurrence. Despite decades of research, the pathogenesis of nephrolithiasis remains incompletely understood, and effective prevention is lacking. An increasing body of evidence suggests that non-coding RNAs, especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play a role in stone formation and stone-related kidney injury. MiRNAs have been studied quite extensively in nephrolithiasis, and a plethora of specific miRNAs have been implicated in the pathogenesis of nephrolithiasis, involving remarkable changes in calcium metabolism, oxalate metabolism, oxidative stress, cell-crystal adhesion, cellular autophagy, apoptosis, and macrophage (Mp) polarization and metabolism. Emerging evidence suggests a potential for miRNAs as novel diagnostic biomarkers of nephrolithiasis. LncRNAs act as competing endogenous RNAs (ceRNAs) to bind miRNAs, thereby modulating mRNA expression to participate in the regulation of physiological mechanisms in kidney stones. Small interfering RNAs (siRNAs) may provide a novel approach to kidney stone prevention and treatment by treating related metabolic conditions that cause kidney stones. Further investigation into these non-coding RNAs will generate novel insights into the mechanisms of renal stone formation and stone-related renal injury and might lead to new strategies for diagnosing and treating this disease.

Epigenetic modification in diabetic kidney disease

Diabetic kidney disease (DKD) is a common microangiopathy in diabetic patients and the main cause of death in diabetic patients. The main manifestations of DKD are proteinuria and decreased renal filtration capacity. The glomerular filtration rate and urinary albumin level are two of the most important hallmarks of the progression of DKD. The classical treatment of DKD is controlling blood glucose and blood pressure. However, the commonly used clinical therapeutic strategies and the existing biomarkers only partially slow the progression of DKD and roughly predict disease progression. Therefore, novel therapeutic methods, targets and biomarkers are urgently needed to meet clinical requirements. In recent years, increasing attention has been given to the role of epigenetic modification in the pathogenesis of DKD. Epigenetic variation mainly includes DNA methylation, histone modification and changes in the noncoding RNA expression profile, which are deeply involved in DKD-related inflammation, oxidative stress, hemodynamics, and the activation of abnormal signaling pathways. Since DKD is reversible at certain disease stages, it is valuable to identify abnormal epigenetic modifications as early diagnosis and treatment targets to prevent the progression of end-stage renal disease (ESRD). Because the current understanding of the epigenetic mechanism of DKD is not comprehensive, the purpose of this review is to summarize the role of epigenetic modification in the occurrence and development of DKD and evaluate the value of epigenetic therapies in DKD.

miR-124-3p improves mitochondrial function of renal tubular epithelial cells in db/db mice

Diabetic kidney disease (DKD) is one of the most serious complications of diabetes mellitus (DM) and the main cause of end-stage renal failure. However, the pathogenesis of DKD is complicated. In this study, we found that miR-124-3p plays a key role in regulating renal mitochondrial function and explored its possible mechanism in DKD progression by performing a series of in vitro and in vivo experiments. Decreased expression of miR-124-3p was found in db/db mice compared to db/m mice. Moreover, miR-124-3p down-regulated FOXQ1 by targeting FOXQ1 mRNA 3'-UTR in NRK-52E cells. Also, an increase in FOXQ1 and down-regulation of Sirt4 were found in db/db mouse kidney and renal tubular epithelial cells cultured with high glucose and high lipid. Overexpression of FOXQ1 could further down-regulate the expression of Sirt4 and aggravate the damage of mitochondria. Conversely, the knockdown of the FOXQ1 gene induced Sirt4 expression and partially restored mitochondrial function. To verify the effects of miR-124-3p on Sirt4 and mitochondria, we found that miR-124-3p mimics could up-regulate Sirt4 and inhibit ROS production and MitoSOX, thus restoring the number and morphology of mitochondria. These results showed that under high-glucose and high-lipid conditions, the down-regulation of miR-124-3p induces FOXQ1 in renal tubular epithelial cells, which in turn suppresses Sirt4 and leads to mitochondrial dysfunction, promoting the development of DKD.

Pediatric Diabetic Nephropathy: Novel Insights from microRNAs

Diabetic nephropathy (DN) represents the most common microvascular complication in patients with diabetes. This progressive kidney disease has been recognized as the major cause of end-stage renal disease with higher morbidity and mortality. However, its tangled pathophysiology is still not fully known. Due to the serious health burden of DN, novel potential biomarkers have been proposed to improve early identification of the disease. In this complex landscape, several lines of evidence supported a critical role of microRNAs (miRNAs) in regulating posttranscriptional levels of protein-coding genes involved in DN pathophysiology. Indeed, intriguing data showed that deregulation of certain miRNAs (e.g., miRNAs 21, -25, -92, -210, -126, -216, and -377) were pathogenically linked to the onset and the progression of DN, suggesting not only a role as early biomarkers but also as potential therapeutic targets. To date, these regulatory biomolecules represent the most promising diagnostic and therapeutic options for DN in adult patients, while similar pediatric evidence is still limited. More, findings from these elegant studies, although promising, need to be deeper investigated in larger validation studies. In an attempt to provide a comprehensive pediatric overview in the field, we aimed to summarize the most recent evidence on the emerging role of miRNAs in pediatric DN pathophysiology.

MicroRNA Expression Profiling in Age-Dependent Renal Impairment

Background

Age-dependent renal impairment contributes to renal dysfunction in both the general population and young and middle-aged patients with renal diseases. Pathological changes in age-dependent renal impairment include glomerulosclerosis and tubulointerstitial fibrosis. The molecules involved in age-dependent renal impairment are not fully elucidated. MicroRNA (miRNA) species were reported to modulate various renal diseases, but the miRNA species involved in age-dependent renal impairment are unclear. Here, we investigated miRNAs in age-dependent renal impairment, and we evaluated their potential as biomarkers and therapeutic targets.

Methods

We conducted an initial microarray profiling analysis to screen miRNAs whose expression levels changed in kidneys of senescence-accelerated resistant (SAMR1)-10-week-old (wk) mice and SAMR1-50wk mice and senescence-accelerated prone (SAMP1)-10wk mice and SAMP1-50wk mice. We then evaluated the expressions of differentially expressed miRNAs in serum from 13 older patients (&gt;65 years old) with age-dependent renal impairment (estimated glomerular filtration ratio &lt;60 mL/min/1.73 m2) by a quantitative real-time polymerase chain reaction (qRT-PCR) and compared the expressions with those of age-matched subjects with normal renal function. We also administered miRNA mimics or inhibitors (5 nmol) with a non-viral vector (polyethylenimine nanoparticles: PEI-NPs) to SAMP1-20wk mice to investigate the therapeutic effects.

Results

The qRT-PCR revealed a specific miRNA (miRNA-503-5p) whose level was significantly changed in SAMP1-50wk mouse kidneys in comparison to the controls. The expression level of miRNA-503-5p was upregulated in the serum of the 13 patients with age-dependent renal impairment compared to the age-matched subjects with normal renal function. The administration of a miRNA-503-5p-inhibitor with PEI-NPs decreased the miRNA-503-5p expression levels, resulting in the inhibition of renal fibrosis in mice via an inhibition of a pro-fibrotic signaling pathway and a suppression of glomerulosclerosis in mice by inhibiting intrinsic signaling pathways.

Conclusion

The serum levels of miRNA-503-5p were decreased in patients with age-dependent renal impairment. However, inhibition of miRNA-503-5p had no effect on age-dependent renal impairment, although inhibition of miRNA-503-5p had therapeutic effects on renal fibrosis and glomerulosclerosis in an in vivo animal model. These results indicate that miRNA-503-5p might be related to age-dependent renal impairment.

β-Amyrin ameliorates diabetic nephropathy in mice and regulates the miR-181b-5p/HMGB2 axis in high glucose-stimulated HK-2 cells

Diabetic nephropathy (DN) is a diabetic complication that can cause renal failure. β-amyrin has been identified to possess anti-diabetic property. This study was designed to evaluate the potential role of β-amyrin in DN and its underlying mechanism. Streptozotocin-induced diabetic mice were used as the in vivo model, and high glucose (HG)-stimulated human proximal tubular HK-2 cells were utilized as the in vitro model. Renal histological changes in mice were assessed by hematoxylin-eosin and periodic acid-Schiff staining. HK-2 cell viability and apoptosis were detected by Cell Counting Kit-8 assay and flow cytometry analysis, respectively. β-amyrin was found to ameliorate kidney injury in DN mice and suppressed inflammatory response as well as apoptosis of HG-stimulated HK-2 cells. miR-181-5p expression in murine renal tissues and HK-2 cells was detected by in situ hybridization (ISH) and fluorescence in situ hybridization (FISH). MiR-181b-5p, a previously identified target for diabetic kidney disease, was downregulated in renal tissues and HG stimulated HK-2 cells, and β-amyrin induced the upregulation of miR-181b-5p. Binding relationship between miR-181b-5p and high mobility group box 2 (HMGB2) was confirmed by luciferase reporter assay. MiR-181b-5p bound to 3' untranslated region of HMGB2 to suppress its expression. As shown by immunohistochemical staining and immunofluorescence staining, HMGB2 was upregulated in the in vivo and in vitro models of DN, and β-amyrin induced the downregulation of HMGB2. Moreover, HMGB2 overexpression neutralized the suppressive effects of miR-181b-5p elevation on the inflammatory response and apoptosis of HG-treated HK-2 cells. Overall, β-amyrin ameliorates DN in mice and suppresses inflammatory response and apoptosis of HG-stimulated HK-2 cells via the miR-181b-5p/HMGB2 axis.