Therapeutic potential of microRNAs for the treatment of renal fibrosis and CKD

New insights into the cardio-renal benefits of SGLT2 inhibitors and the coordinated role of miR-30 family

Sodium-glucose co-transporter inhibitors (SGLTis) are the latest class of anti-hyperglycemic agents. In addition to inhibiting the absorption of glucose by the kidney causing glycosuria, these drugs also demonstrate cardio-renal benefits in diabetic subjects. miR-30 family, one of the most abundant microRNAs in the heart, has recently been linked to a setting of cardiovascular diseases and has been proposed as novel biomarkers in kidney dysfunctions as well; their expression is consistently dysregulated in a variety of cardio-renal dysfunctions. The mechanistic involvement and the potential interplay between miR-30 and SGLT2i effects have yet to be thoroughly elucidated. Recent research has stressed the relevance of this cluster of microRNAs as modulators of several pathological processes in the heart and kidneys, raising the possibility of these small ncRNAs playing a central role in various cardiovascular complications, notably, endothelial dysfunction and pathological remodeling. Here, we review current evidence supporting the pleiotropic effects of SGLT2is in cardiovascular and renal outcomes and investigate the link and the coordinated implication of the miR-30 family in endothelial dysfunction and cardiac remodeling. We also discuss the emerging role of circulating miR-30 as non-invasive biomarkers and attractive therapeutic targets for cardiovascular diseases and kidney diseases. Clinical evidence, as well as metabolic, cellular, and molecular aspects, are comprehensively covered.

Epigenetic mechanisms differentially regulate blood pressure and renal dysfunction in male and female Npr1 haplotype mice

We determined the epigenetic mechanisms regulating mean arterial pressure (MAP) and renal dysfunction in guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) gene-targeted mice. The Npr1 (encoding NPRA) gene-targeted mice were treated with class 1 specific histone deacetylase inhibitor (HDACi) mocetinostat (MGCD) to determine the epigenetic changes in a sex-specific manner. Adult male and female Npr1 haplotype (1-copy; Npr1+/-), wild-type (2-copy; Npr1+/+), and gene-duplicated heterozygous (3-copy; Npr1++/+) mice were intraperitoneally injected with MGCD (2 mg/kg) for 14 days. BP, renal function, histopathology, and epigenetic changes were measured. One-copy male mice showed significantly increased MAP, renal dysfunction, and fibrosis than 2-copy and 3-copy mice. Furthermore, HDAC1/2, collagen1alpha-2 (Col1α-2), and alpha smooth muscle actin (α-SMA) were significantly increased in 1-copy mice compared with 2-copy controls. The expression of antifibrotic microRNA-133a was attenuated in 1-copy mice but to a greater extent in males than females. NF-κB was localized at significantly lower levels in cytoplasm than in the nucleus with stronger DNA binding activity in 1-copy mice. MGCD significantly lowered BP, improved creatinine clearance, and repaired renal histopathology. The inhibition of class I HDACs led to a sex-dependent distinctive stimulation of acetylated positive histone marks and inhibition of methylated repressive histone marks in Npr1 1-copy mice; however, it epigenetically lowered MAP, repaired renal fibrosis, and proteinuria and suppressed NF-kB differentially in males versus females. Our results suggest a role for epigenetic targets affecting hypertension and renal dysfunction in a sex-specific manner.

Optimized rAAV8 targeting acinar KLF4 ameliorates fibrosis in chronic pancreatitis via exosomes-enriched let-7s suppressing pancreatic stellate cells activation

Chronic pancreatitis (CP) is marked by progressive fibrosis and the activation of pancreatic stellate cells (PSCs), accompanied by the destruction of pancreatic parenchyma, leading to the loss of acinar cells (ACs). Few research studies have explored the mechanism by which damaged ACs (DACs) contribute to PSCs activation and pancreatic fibrosis. Currently, there are no effective drugs for curing CP or limiting the progression of pancreatic fibrosis. In this research, co-culture with intact acinar cells (IACs) suppressed PSC activation, while co-culture with DACs did the opposite. Krüppel-like factor 4 (KLF4) was significantly upregulated in DACs and was established as the key molecule that switches ACs from PSCs-suppressor to PSCs-activator. We revealed the exosomes of IACs contributed to the anti-activated function of IACs-CS on PSCs. MiRNome profiling showed that let-7 family is significantly enriched in IAC-derived exosomes (>30% miRNome), which partially mediates IACs' suppressive impacts on PSCs. Furthermore, it has been observed that the enrichment of let-7 in exosomes was influenced by the expression level of KLF4. Mechanistic studies demonstrated that KLF4 in ACs upregulated Lin28A, thereby decreasing let-7 levels in AC-derived exosomes, and thus promoting PSCs activation. We utilized an adeno-associated virus specifically targeting KLF4 in ACs (shKLF4-pAAV) to suppress PSCs activation in CP, resulting in reduced pancreatic fibrosis. IAC-derived exosomes hold potential as potent weapons against PSCs activation via let-7s, while activated KLF4/Lin28A signaling in DACs diminished such functions. ShKLF4-pAAV holds promise as a novel therapeutic approach for CP.

Research progress on miR-124-3p in the field of kidney disease

MicroRNAs (miRNAs) are 18-25 nucleotides long, single-stranded, non-coding RNA molecules that regulate gene expression. They play a crucial role in maintaining normal cellular functions and homeostasis in organisms. Studies have shown that miR-124-3p is highly expressed in brain tissue and plays a significant role in nervous system development. It is also described as a tumor suppressor, regulating biological processes like cancer cell proliferation, apoptosis, migration, and invasion by controlling multiple downstream target genes. miR-124-3p has been found to be involved in the progression of various kidney diseases, including diabetic kidney disease, calcium oxalate kidney stones, acute kidney injury, lupus nephritis, and renal interstitial fibrosis. It mediates these processes through mechanisms like oxidative stress, inflammation, autophagy, and ferroptosis. To lay the foundation for future therapeutic strategies, this research group reviewed recent studies on the functional roles of miR-124-3p in renal diseases and the regulation of its downstream target genes. Additionally, the feasibility, limitations, and potential application of miR-124-3p as a diagnostic biomarker and therapeutic target were thoroughly investigated.

MiR-150-5p Alleviates Renal Tubule Epithelial Cell Fibrosis via the Inhibition of Epithelial-Mesenchymal Transition by Targeting ZEB1

INTRODUCTION

Although microRNA (miR)-150-5p participates in the progression of renal fibrosis, its mechanism of action remains elusive.

METHODS

A mouse model of unilateral ureteral obstruction was used. The in vitro renal fibrosis model was established by stimulating human kidney 2 (HK-2) cells with transforming growth factor beta 1 (TGF-β1). The expression profiles of miR-150-5p, zinc finger E-box binding homeobox 1 (ZEB1), and other fibrosis- and epithelial-mesenchymal transition (EMT)-linked proteins were determined using Western blot and quantitative reverse transcription polymerase chain reaction. The relationship between miR-150-5p and ZEB1 in HK-2 cells was confirmed by a dual-luciferase reporter assay.

RESULTS

Both in vivo and in vitro renal fibrosis models revealed reduced miR-150-5p expression and elevated ZEB1 level. A significant decrease in E-cadherin levels, as well as increases in alpha smooth muscle actin (α-SMA) and collagen type I (Col-I) levels, was seen in TGF-β1-treated HK-2 cells. The overexpression of miR-150-5p ameliorated TGF-β1-mediated fibrosis and EMT. Notably, miR-150-5p acts by directly targeting ZEB1. A significant reversal of the inhibitory impact of miR-150-5p on TGF-β1-mediated fibrosis and EMT in HK-2 cells was observed upon ZEB1 overexpression.

CONCLUSION

MiR-150-5p suppresses TGF-β1-induced fibrosis and EMT by targeting ZEB1 in HK-2 cells, providing helpful insights into the therapeutic intervention of renal fibrosis.

Long non-coding RNAs as emerging regulators of miRNAs and epigenetics in diabetes-related chronic kidney disease

Diabetes is one of the major cause of chronic kidney disease (CKD), including "diabetic nephropathy," and is an increasingly prevalent accelerator of the progression of non-diabetic forms of CKD. The long non-coding RNAs (lncRNAs) have come into the limelight in the past few years as one of the emerging weapons against CKD in diabetes. Available data over the past few years demonstrate the interaction of lncRNAs with miRNAs and epigenetic machinery. Interestingly, the evolving data suggest that lncRNAs play a vital role in diabetes-associated CKD by regulation of epigenetic enzymes such as DNA methyltransferase, histone deacetylases, and histone methyltransferases. LncRNAs are also engaged in the regulation of several miRNAs in diabetic nephropathy. Hence this review will elaborate on the association between lncRNAs and their interaction with epigenetic regulators involved in different aspects and thus the progression of CKD in diabetes.

Downregulating ANGPTL3 by miR-144-3p promoted TGF-β1-induced renal interstitial fibrosis via activating PI3K/AKT signaling pathway

Despite observations of decreased ANGPTL3 (angiopoietin-like protein 3) levels in tubular atrophy and renal interstitial fibrosis (RIF), its functional implications and regulatory mechanisms in RIF remain unclear. This investigation employed unilateral ureteral obstruction (UUO) mice as in vivo model and human proximal kidney tubuloepithelial HK-2 cells under TGF-β1 treatment as in vitro model to explore RIF. The RIF extent was evaluated using H & E staining and Masson's trichrome staining. There was a significant decrease in ANGPTL3 levels and an increase in miR-144-3p, accompanied by heightened expressions of α-SMA, p-PI3K, p-AKT, Collagen I, and Fibronectin in the UUO mice and HK-2 cells treated with TGF-β1. Enhancing ANGPTL3 expression or suppressing miR-144-3p mitigated TGF-β1-induced cellular apoptosis, inflammation, and PI3K/AKT signaling pathway activation, as evidenced by altered levels of α-SMA, Collagen I, Fibronectin, and associated signaling markers. Using a bioinformatics approach, a miR-144-3p binding site was discovered on the ANGPTL3 mRNA, and this finding was subsequently confirmed through luciferase reporter assay. In HK-2 cells stimulated with TGF-β1, the suppression of ANGPTL3 negated the effects of inhibiting miR-144-3p. Under comparable conditions, the use of LY294002, an inhibitor of the PI3K/AKT pathway, nullified the effects caused by the knockdown of ANGPTL3. Collectively, these findings indicate that miR-144-3p exacerbates RIF through PI3K/AKT pathway activation by targeting ANGPTL3, highlighting a novel potential therapeutic target for RIF management.

Modulation of miR-29a and miR-29b Expression and Their Target Genes Related to Inflammation and Renal Fibrosis by an Oral Nutritional Supplement with Probiotics in Malnourished Hemodialysis Patients

Malnutrition is prevalent in patients with chronic kidney disease (CKD), especially those on hemodialysis. Recently, our group described that a new oral nutritional supplement (ONS), specifically designed for malnourished (or at risk) hemodialysis patients with a "similar to the Mediterranean diet" pattern, improved caloric-protein intake, nutritional status and biomarkers of inflammation and oxidation. Our aim in this study was to evaluate whether the new ONS, associated with probiotics or not, may produce changes in miRNA's expression and its target genes in malnourished hemodialysis patients, compared to individualized diet recommendations. We performed a randomized, multicenter, parallel-group trial in malnourished hemodialysis patients with three groups (1: control (C) individualized diet (n = 11); 2: oral nutritional supplement (ONS) + placebo (ONS-PL) (n = 10); and 3: ONS + probiotics (ONS-PR) (n = 10)); the trial was open regarding the intake of ONS or individualized diet recommendations but double-blinded for the intake of probiotics. MiRNAs and gene expression levels were analyzed by RT-qPCR at baseline and after 3 and 6 months. We observed that the expression of miR-29a and miR-29b increased significantly in patients with ONS-PR at 3 months in comparison with baseline, stabilizing at the sixth month. Moreover, we observed differences between studied groups, where miR-29b expression levels were elevated in patients receiving ONS-PR compared to the control group in the third month. Regarding the gene expression levels, we observed a decrease in the ONS-PR group compared to the control group in the third month for RUNX2 and TNFα. TGFB1 expression was decreased in the ONS-PR group compared to baseline in the third month. PTEN gene expression was significantly elevated in the ONS-PR group at 3 months in comparison with baseline. LEPTIN expression was significantly increased in the ONS-PL group at the 3-month intervention compared to baseline. The new oral nutritional supplement associated with probiotics increases the expression levels of miR-29a and miR-29b after 3 months of intervention, modifying the expression of target genes with anti-inflammatory and anti-fibrotic actions. This study highlights the potential benefit of this oral nutritional supplement, especially associated with probiotics, in malnourished patients with chronic renal disease on hemodialysis.

The Role of miRNA in Renal Fibrosis Leading to Chronic Kidney Disease

Chronic kidney disease (CKD) is an important health concern that is expected to be the fifth most widespread cause of death worldwide by 2040. The presence of chronic inflammation, oxidative stress, ischemia, etc., stimulates the development and progression of CKD. Tubulointerstitial fibrosis is a common pathomechanism of renal dysfunction, irrespective of the primary origin of renal injury. With time, fibrosis leads to end-stage renal disease (ESRD). Many studies have demonstrated that microRNAs (miRNAs, miRs) are involved in the onset and development of fibrosis and CKD. miRNAs are vital regulators of some pathophysiological processes; therefore, their utility as therapeutic agents in various diseases has been suggested. Several miRNAs were demonstrated to participate in the development and progression of kidney disease. Since renal fibrosis is an important problem in chronic kidney disease, many scientists have focused on the determination of miRNAs associated with kidney fibrosis. In this review, we present the role of several miRNAs in renal fibrosis and the potential pathways involved. However, as well as those mentioned above, other miRs have also been suggested to play a role in this process in CKD. The reports concerning the impact of some miRNAs on fibrosis are conflicting, probably because the expression and regulation of miRNAs occur in a tissue- and even cell-dependent manner. Moreover, different assessment modes and populations have been used. There is a need for large studies and clinical trials to confirm the role of miRs in a clinical setting. miRNAs have great potential; thus, their analysis may improve diagnostic and therapeutic strategies.

Mitochondrial dysfunction and oxidative stress: Role in chronic kidney disease

Chronic kidney disease (CKD) is associated with a variety of distinct disease processes that permanently change the function and structure of the kidney across months or years. CKD is characterized as a glomerular filtration defect or proteinuria that lasts longer than three months. In most instances, CKD leads to end-stage kidney disease (ESKD), necessitating kidney transplantation. Mitochondrial dysfunction is a typical response to damage in CKD patients. Despite the abundance of mitochondria in the kidneys, variations in mitochondrial morphological and functional characteristics have been associated with kidney inflammatory responses and injury during CKD. Despite these variations, CKD is frequently used to define some classic signs of mitochondrial dysfunction, including altered mitochondrial shape and remodeling, increased mitochondrial oxidative stress, and a marked decline in mitochondrial biogenesis and ATP generation. With a focus on the most significant developments and novel understandings of the involvement of mitochondrial remodeling in the course of CKD, this article offers a summary of the most recent advances in the sources of procured mitochondrial dysfunction in the advancement of CKD. Understanding mitochondrial biology and function is crucial for developing viable treatment options for CKD.

Role of microRNAs in programmed cell death in renal diseases: A review

MicroRNAs (miRNAs) regulate gene expression involving kidney morphogenesis and cell proliferation, apoptosis, differentiation, migration, invasion, immune evasion, and extracellular matrix remodeling. Programmed cell death (PCD) is mediated and regulated by specific genes and a wealth of miRNAs, which participate in various pathological processes. Dysregulation of miRNAs can disrupt renal development and induce the onset and progression of various renal diseases. An in-depth understanding of how miRNAs regulate renal development and diseases is indispensable to comprehending how they can be used in new diagnostic and therapeutic approaches. However, the mechanisms are still insufficiently investigated. Hence, we review the current roles of miRNA-related signaling pathways and recent advances in PCD research and aim to display the potential crosstalk between miRNAs and PCD. The prospects of miRNAs as novel biomarkers and therapeutic targets are also described, which might provide some novel ideas for further studies.

Emodin ameliorates renal injury and fibrosis via regulating the miR-490-3p/HMGA2 axis

Renal fibrosis is a major pathological feature of chronic kidney disease (CKD). While emodin is reported to elicit anti-fibrotic effects on renal injury, little is known about its effects on microRNA (miRNA)-modulated mechanisms in renal fibrosis. In this study, we established a unilateral ureteral obstruction (UUO) model and a transforming growth factor (TGF)-β1-induced normal rat renal tubular epithelial cell line (NRK-52E) model to investigate the protective effects of emodin on renal fibrosis and its miRNA/target gene mechanisms. Dual-luciferase assay was performed to confirm the direct binding of miRNA and target genes in HEK293 cells. Results showed that oral administration of emodin significantly ameliorated the loss of body weight and the increase in physicochemical parameters, including serum uric acid, creatinine, and urea nitrogen in UUO mice. Inflammatory cytokines, including tumor necrosis factor-α, monocyte chemoattractant protein-1, and interleukin (IL)-1β, but not IL-6, were down-regulated by emodin administration. Emodin decreased the expression levels of TGF-β1 and fibrotic-related proteins, including alpha-smooth muscle actin, Collagen IV, and Fibronectin, and increased the expression of E-cadherin. Furthermore, miR-490-3p was decreased in UUO mice and negatively correlated with increased expression of high migration protein A2 (HMGA2). We further confirmed HMGA2 was the target of miR-490-3p. Transfection of miR-490-3p mimics decreased, while transfection of miR-490-3p inhibitors increased fibrotic-related proteins and HMGA2 expression levels in TGF-β1-induced NRK-52E cells. Furthermore, transfection of miR-490-3p mimics enhanced the anti-fibrotic effects of emodin, while transfection of miR-490-3p inhibitors abolished the protective effects of emodin. Thus, as a novel target of emodin that prevents renal fibrosis in the HMGA2-dependent signaling pathway, miR-490-3p has potential implications in CKD pathology.

Endosulfan induced kidney cell injury by modulating ACE2 through up-regulating miR-429 in HK-2 cells

Endosulfan, a typical organochlorine pesticide, is widely used in agricultural countries and was detected in blood samples from the general population. Studies have shown a positive correlation between chronic kidney disease of unknown aetiology (CKDu) and endosulfan. CKDu has become endemic in agricultural countries, with clinical manifestations of tubulointerstitial fibrosis.The goal of this study was to investigate the effects of endosulfan in kidney cell injury in human renal tubular epithelial cells (HK-2), focusing on apoptosis, inflammatory response, and epithelial-mesenchymal transition (EMT). We found that endosulfan induced apoptosis in HK-2 cells by up-regulating the expression of BAX, APAF-1, Caspase-3 and mitochondrial Cytochrome c was released into the cytosol. Endosulfan caused an inflammatory response, showing the increase in the secretion and mRNA expression levels of IL-6/IL-8. Endosulfan triggered EMT, characterized by downregulation of E-cadherin and upregulation of Vimentin. Western blot results showed that p-Smad3 and Smad3 protein expression were elevated while the expression of Smad7 were decreased in endosulfan-exposed groups. Dual luciferase reporter assay confirmed the potential binding capacity of miR-429 to 3'-UTR of ACE2. Endosulfan causes upregulation of miR-429 and downregulation of ACE2 in HK-2 cells. Overexpression of miR-429 or silencing of ACE2 in HK-2 cells caused apoptosis, inflammation and EMT through TGF signaling pathway. These findings suggest that endosulfan can lead to kidney cell injury by modulating ACE2 through up-regulating miR-429, providing new evidence for the pathogenesis of CKDu.

miR-122-5p Regulates Renal Fibrosis In Vivo

The role of exogenous microRNAs (miRNAs) in renal fibrosis is poorly understood. Here, the effect of exogenous miRNAs on renal fibrosis was investigated using a renal fibrosis mouse model generated by unilateral ureteral obstruction (UUO). miRNA microarray analysis and quantitative reverse-transcription polymerase chain reaction showed that miR-122-5p was the most downregulated (0.28-fold) miRNA in the kidneys of UUO mice. The injection of an miR-122-5p mimic promoted renal fibrosis and upregulated COL1A2 and FN1, whereas an miR-122-5p inhibitor suppressed renal fibrosis and downregulated COL1A2 and FN1. The expression levels of fibrosis-related mRNAs, which were predicted targets of miR-122-5p, were evaluated. The expression level of TGFBR2, a pro-fibrotic mRNA, was upregulated by the miR-122-5p mimic, and the expression level of FOXO3, an anti-fibrotic mRNA, was upregulated by the miR-122-5p inhibitor. The protein expressions of TGFBR2 and FOXO3 were confirmed by immunohistochemistry. Additionally, the expression levels of LC3, downstream anti-fibrotic mRNAs of FOXO3, were upregulated by the miR-122-5p inhibitor. These results suggest that miR-122-5p has critical roles in renal fibrosis.

Trefoil factor 3: New highlights in chronic kidney disease research

Trefoil factor 3 (TFF3, also known as intestinal trefoil factor) is a small-molecule peptide containing a typical trefoil structure. TFF3 has several biological effects, such as wound healing, immune regulation, neuroprotection, and cell migration and proliferation promotion. Although TFF3 binding sites were identified in rat kidneys more than a decade ago, the specific effects of this small-molecule peptide on kidneys remain unclear. Until recently, much of the research on TFF3 in the kidney field has focused exclusively on its role as a biomarker. Notably, a large prospective randomized study of patients with 29 common clinical diseases revealed that chronic kidney disease (CKD) was associated with the highest serum TFF3 levels, which were 3-fold higher than in acute gastroenteritis, which had the second-highest levels. Examination of each stage of CKD revealed that urine and serum TFF3 levels significantly increased with the progression of CKD. These results suggest that the role of TFF3 in CKD needs further research. The present review summarizes the renal physiological expression, biological functions, and downstream signaling of TFF3, as well as the upstream events that lead to high expression of TFF3 in CKD.

Cell-Matrix Interactions in Renal Fibrosis

Renal fibrosis is a hallmark of end-stage chronic kidney disease. It is characterized by increased accumulation of extracellular matrix (ECM), which disrupts cellular organization and function within the kidney. Here, we review the bi-directional interactions between cells and the ECM that drive renal fibrosis. We will discuss the cells involved in renal fibrosis, changes that occur in the ECM, the interactions between renal cells and the surrounding fibrotic microenvironment, and signal transduction pathways that are misregulated as fibrosis proceeds. Understanding the underlying mechanisms of cell-ECM crosstalk will identify novel targets to better identify and treat renal fibrosis and associated renal disease.

Investigating the possible mechanisms of pirfenidone to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2

Pirfenidone (PFD) is a non-peptide synthetic chemical that inhibits the production of transforming growth factor-beta 1 (TGF-β1), tumor necrosis factor-alpha (TNF-α), platelet-derived growth factor (PDGF), Interleukin 1 beta (IL-1β), and collagen 1 (COL1A1), all of which have been linked to the prevention or removal of excessive scar tissue deposition in many organs. PFD has been demonstrated to decrease apoptosis, downregulate angiotensin-converting enzyme (ACE) receptor expression, reduce inflammation through many routes, and alleviate oxidative stress in pneumocytes and other cells while protecting them from COVID-19 invasion and cytokine storm. Based on the mechanism of action of PFD and the known pathophysiology of COVID-19, it was recommended to treat COVID-19 patients. The use of PFD as a treatment for a range of disorders is currently being studied, with an emphasis on outcomes related to reduced inflammation and fibrogenesis. As a result, rather than exploring the molecule's chemical characteristics, this review focuses on innovative PFD efficacy data. Briefly, herein we tried to investigate, discuss, and illustrate the possible mechanisms of actions for PFD to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2 candidate.

MicroRNAs in kidney development and disease

MicroRNAs (miRNAs) belong to a class of endogenous small noncoding RNAs that regulate gene expression at the posttranscriptional level, through both translational repression and mRNA destabilization. They are key regulators of kidney morphogenesis, modulating diverse biological processes in different renal cell lineages. Dysregulation of miRNA expression disrupts early kidney development and has been implicated in the pathogenesis of developmental kidney diseases. In this Review, we summarize current knowledge of miRNA biogenesis and function and discuss in detail the role of miRNAs in kidney morphogenesis and developmental kidney diseases, including congenital anomalies of the kidney and urinary tract and Wilms tumor. We conclude by discussing the utility of miRNAs as potentially novel biomarkers and therapeutic agents.

Silencing of LncRNA KCNQ1OT1 confers an inhibitory effect on renal fibrosis through repressing miR-124-3p activity

LncRNA have been increasingly shown that plays pivotal roles in the development of various diseases, including renal fibrosis. Nevertheless, the pathological function of Long non-coding RNA KCNQ1OT1 (KCNQ1OT1) in the renal fibrosis remains obscure. Unilateral ureteral obstruction (UUO) was used to induce renal fibrosis. We detected the expression levels of KCNQ1OT1 in the TGF-β1-induced HK-2 cells via RT-qPCR analysis. The functions of KCNQ1OT1 on the progression of renal fibrosis were examined by CCK-8, EdU, dual-luciferase reporter, and immunofluorescence analyses. In the present study, we found that sh-KCNQ1OT1 obviously attenuated UUO-induced renal fibrosis. Moreover, production of extracellular matrix (ECM), including α-SMA and Fibronectin levels, was significantly increased in kidney and HK-2 cells after UUO or TGF-β stimulation. Knockdown of KCNQ1OT1 inhibited cell proliferation and inhibits the α-SMA and Fibronectin expression of TGF-β1-induced HK-2 cells. In addition, bioinformatics analysis and dual-luciferase reporter assay indicated that miR-124-3p was a target gene of KCNQ1OT1. Mechanistically, silencing miR-124-3p abolished the repressive effects of KCNQ1OT1 on TGF-β1-induced HK-2 cells. In conclusion, KCNQ1OT1 knockdown plays an anti-fibrotic effect through promotion of miR-124-3p expression in renal fibrosis, which provides a promising therapeutic target for the treatment of renal fibrosis.

Exosomes from miR-374a-5p-modified mesenchymal stem cells inhibit the progression of renal fibrosis by regulating MAPK6/MK5/YAP axis

Chronic kidney disease (CKD) in clinical is defined as a gradual loss of kidney function for more than 3 months. The pathologic course of CKD is characterized by extensive renal fibrosis; thus, preventing renal fibrosis is vital for the treatment of CKD. It has been reported that microRNA (miR)-374a-5p was under-expressed in renal venous blood samples from patients with CKD. In addition, it exhibited anti-apoptotic effects in renal tissues suggesting that miR-374a-5p may play an important role in CKD. However, it is not clear whether miR-374a-5p could be delivered to renal cells by exosomes and exerts anti-renal fibrosis effects. To mimic renal fibrosis in vitro, human renal tubular epithelial cell lines (HK-2 cells) were treated by transforming growth factor-β (TGF-β) 1. Reverse transcription-quantitative polymerase-chain reaction (RT-qPCR) or Western blot was carried out to evaluate the mechanism by which miR-374a-5p regulated the development of renal fibrosis. Next, exosomes were isolated using with ultracentrifugation method, and the relationship between miR-374a-5p and MAPK6 was evaluated using dual-Luciferase a reporter assay system. The results indicated TGF-β1 significantly down-regulated the expression of miR-374a-5p in HK-2 cells and miR-374a-5p agomir remarkably inhibited the progression of fibrosis in vitro. In addition, exosomal miR-374a-5p could be internalized by HK-2 cells and obviously enhanced the level of miR-374a-5p in HK-2 cells. Furthermore, exosomal miR-374a-5p prevented the progression of renal fibrosis in vivo by regulating MAPK6/MK5/YAP axis. In conclusion, exosomal miR-374a-5p inhibited the progression of renal fibrosis by regulating MAPK6/MK5/YAP axis.

Lipid-Based Nanocarriers in Renal RNA Therapy

Kidney disease is a multifactorial problem, with a growing prevalence and an increasing global burden. With the latest worldwide data suggesting that chronic kidney disease (CKD) is the 12th leading cause of death, it is no surprise that CKD remains a public health problem that requires urgent attention. Multiple factors contribute to kidney disease, each with its own pathophysiology and pathogenesis. Furthermore, microRNAs (miRNAs) have been linked to several types of kidney diseases. As dysregulation of miRNAs is often seen in some diseases, there is potential in the exploitation of this for therapeutic applications. In addition, uptake of interference RNA has been shown to be rapid in kidneys making them a good candidate for RNA therapy. The latest advancements in RNA therapy and lipid-based nanocarriers have enhanced the effectiveness and efficiency of RNA-related drugs, thereby making RNA therapy a viable treatment option for renal disease. This is especially useful for renal diseases, for which a suitable treatment is not yet available. Moreover, the high adaptability of RNA therapy combined with the low risk of lipid-based nanocarriers make for an attractive treatment choice. Currently, there are only a small number of RNA-based drugs related to renal parenchymal disease, most of which are in different stages of clinical trials. We propose the use of miRNAs or short interfering RNAs coupled with a lipid-based nanocarrier as a delivery vehicle for managing renal disease.

Therapies Targeting Epigenetic Alterations in Acute Kidney Injury-to-Chronic Kidney Disease Transition

Acute kidney injury (AKI) was previously thought to be a merely transient event; however, recent epidemiological evidence supports the existence of a causal relationship between AKI episodes and subsequent progression to chronic kidney disease (CKD). Although the pathophysiology of this AKI-to-CKD transition is not fully understood, it is mediated by the interplay among multiple components of the kidney including tubular epithelial cells, endothelial cells, pericytes, inflammatory cells, and myofibroblasts. Epigenetic alterations including histone modification, DNA methylation, non-coding RNAs, and chromatin conformational changes, are also expected to be largely involved in the pathophysiology as a “memory” of the initial injury that can persist and predispose to chronic progression of fibrosis. Each epigenetic modification has a great potential as a therapeutic target of AKI-to-CKD transition; timely and target-specific epigenetic interventions to the various temporal stages of AKI-to-CKD transition will be the key to future therapeutic applications in clinical practice. This review elaborates on the latest knowledge of each mechanism and the currently available therapeutic agents that target epigenetic modification in the context of AKI-to-CKD transition. Further studies will elucidate more detailed mechanisms and novel therapeutic targets of AKI-to-CKD transition.

Genome-Wide Admixture Mapping of Estimated Glomerular Filtration Rate and Chronic Kidney Disease Identifies European and African Ancestry-of-Origin Loci in Hispanic and Latino Individuals in the United States

BACKGROUND

Admixture mapping is a powerful approach for gene mapping of complex traits that leverages the diverse genetic ancestry in populations with recent admixture, such as Hispanic or Latino individuals in the United States. These individuals have an increased risk of CKD.

METHODS

We performed genome-wide admixture mapping for both CKD and eGFR in a sample of 12,601 participants from the Hispanic Community Health Study/Study of Latinos, with validation in a sample of 8191 Black participants from the Women's Health Initiative (WHI). We also compared the findings with those from a conventional genome-wide association study.

RESULTS

Three novel ancestry-of-origin loci were identified on chromosomes 2, 14, and 15 for CKD and eGFR. The chromosome 2 locus comprises two European ancestry regions encompassing the FSHR and NRXN1 genes, with European ancestry at this locus associated with increased CKD risk. The chromosome 14 locus, found within the DLK1-DIO3 imprinted domain, was associated with lower eGFR and driven by European ancestry. The eGFR-associated locus on chromosome 15 included intronic variants of RYR3 and was within an African-specific genomic region associated with higher eGFR. The genome-wide association study failed to identify significant associations in these regions. We validated the chromosome 14 and 15 loci associated with eGFR in the WHI Black participants.

CONCLUSIONS

This study provides evidence of shared ancestry-specific genomic regions influencing eGFR in Hispanic or Latino individuals and Black individuals and illustrates the potential for leveraging genetic ancestry in recently admixed populations for the discovery of novel candidate loci for kidney phenotypes.

Screening and identification of key microRNAs and regulatory pathways associated with renal fibrosis process

To reveal the pathogenesis of renal fibrosis. Renal fibrosis was induced with unilateral ureteral obstruction (UUO). Related biochemical indices in rat serum were determined, and histopathological morphology observed. Tissue transcriptome...

Exosomes isolated from melatonin-stimulated mesenchymal stem cells improve kidney function by regulating inflammation and fibrosis in a chronic kidney disease mouse model

Chronic kidney disease (CKD) is defined as structural and functional abnormalities of the kidney due to inflammation and fibrosis. We investigated the therapeutic effects of exosomes secreted by melatonin-stimulated mesenchymal stem cells (Exocue) on the functional recovery of the kidney in a CKD mouse model. Exocue upregulated gene expression of micro RNAs (miRNAs) associated with anti-inflammatory and anti-fibrotic effects. Exocue-treated groups exhibited low tumor necrosis factor-α and transforming growth factor-β levels in serum and fibrosis inhibition in kidney tissues mediated through regulation of cell apoptosis and proliferation of fibrosis-related cells. Exocue treatment decreased the gene expression of CKD progression-related miRNAs. Moreover, the CKD severity was alleviated in the Exocue group via upregulation of aquaporin 2 and 5 levels and reduction of blood urea nitrogen and creatinine, resulting in functional recovery of the kidney. In conclusion, Exocue could be a novel therapeutic agent for treating CKD by regulating inflammation and fibrosis.

MicroRNA miR-4709-3p targets Large Tumor Suppressor Kinase 2 (LATS2) and induces obstructive renal fibrosis through Hippo signaling

Obstructive renal fibrosis is the consequence of abnormal extracellular matrix assembly, which eventually results in renal failure, acute, and end‑stage renal infection. MicroRNAs (miRNAs), a particular category of small RNAs, modulate the expression of genes post-transcriptionally and regulate biological activities, including fibrogenesis. The study probed to estimate the key functions of miR-4709-3p in obstructive renal fibrosis. This investigation used TGF-β1 stimulated HK-2 in-vitro model, unilateral ureteral occlusion (UUO) mice model, and human Diabetic nephropathy (DN) and Renal interstitial fibrosis (RIF) specimens to depict the abundance of the miR-4709-3p level using FISH and RT-qPCR. MiR-4709-3p mimics and inhibitors were utilized to evaluate the functions of miR-4709-3p in-vitro. Luciferase assay was exploited to verify miR-4709-3p and LATS2 3'UTR binding. Finally, to depict the functions of miR-4709-3p in-vivo, the UUO model was injected with miR-4709-3p inhibitors. Results exhibited the upregulation of miR-4709-3p in UUO-induced in-vivo model, TGF-β1 stimulated HK-2, and human RIF and DN samples. Moreover, it was determined that modulating miR-4709-3p regulated the level of fibrosis markers. Luciferase assay miR-4709-3p modulates renal fibrosis by targeting LATS2. Finally, it was found that miR-4709-3p regulates obstructive renal fibrosis through the Hippo signaling pathway. Overall, the study concludes that aberrant miR-4709-3p expression plays an essential function in the renal fibrosis progression, and miR-4709-3p overexpression could advance obstructive renal fibrosis via LATS2 targeting in Hippo signaling pathway. Therefore, miR-4709-3p inhibition may be a potential renal fibrosis therapy target.

Hirudin, a thrombin inhibitor, attenuates TGF-β-induced fibrosis in renal proximal tubular epithelial cells by inhibition of protease-activated receptor 1 expression via S1P/S1PR2/S1PR3 signaling

Renal interstitial fibrosis (RIF) is the final common outcome of numerous chronic kidney diseases, contributing to end-stage renal disease. Hirudin, a thrombin inhibitor, has attracted increased attention as a potential treatment approach for renal fibrosis. The present study aimed to investigate the molecular mechanism underlying the effect of hirudin on fibrosis in renal proximal tubular epithelial cells. An in vivo mouse RIF model established using unilateral ureteral obstruction (UUO) and an in vitro of RIF using the renal tubular epithelial cell line HK-2 treated with TGF-β were used. Expressions of sphingosine-1-phosphate (S1P) receptors (S1PR)1-4 and protease-activated receptor 1 (PAR1) were measured by reverse transcription-quantitative PCR and western blotting in mice with UUO and TGF-β induced HK-2 cells. Western blotting was used to detect the expression of N-cadherin, Slug, E-cadherin, Collagen IV, fibronectin, MMP9 and monocyte chemoattractant protein-1. Immunofluorescence staining was conducted to measure α-SMA level expression. The results demonstrated that the expression levels of S1PR1, S1PR2, S1PR3, S1PR4 and PAR1 were upregulated in both TGF-β-induced HK-2 cells and renal tissues from mice with unilateral ureteral ligation. Notably, hirudin inhibited TGF-β-induced PAR1, S1PR2 and S1PR3 upregulation in both HK-2 cells and renal tissues. Additionally, the inhibition of S1PR2 and S1PR3 resulted in PAR1 downregulation. Furthermore, treatment with S1P and PAR1 agonists abolished the effect of hirudin on the expression of EMT, fibrosis-related proteins and monocyte chemoattractant protein 1. In conclusion, hirudin attenuated TGF-β-induced fibrosis in proximal renal tubular epithelial HK-2 cells by inhibiting PAR1 expression via the S1P/S1PR2/S1PR3 signaling pathway. Therefore, hirudin may be considered as a promising therapeutic agent for RIF.

Role of microRNAs in Obesity-Related Kidney Disease

Obesity is a major global health problem and is associated with a significant risk of renal function decline. Obesity-related nephropathy, as one of the complications of obesity, is characterized by a structural and functional damage of the kidney and represents one of the important contributors to the morbidity and mortality worldwide. Despite increasing data linking hyperlipidemia and lipotoxicity to kidney injury, the apprehension of molecular mechanisms leading to a development of kidney damage is scarce. MicroRNAs (miRNAs) are endogenously produced small noncoding RNA molecules with an important function in post-transcriptional regulation of gene expression. miRNAs have been demonstrated to be important regulators of a vast array of physiological and pathological processes in many organs, kidney being one of them. In this review, we present an overview of miRNAs, focusing on their functional role in the pathogenesis of obesity-associated renal pathologies. We explain novel findings regarding miRNA-mediated signaling in obesity-related nephropathies and highlight advantages and future perspectives of the therapeutic application of miRNAs in renal diseases.

Tubular cell-derived exosomal miR-150-5p contributes to renal fibrosis following unilateral ischemia-reperfusion injury by activating fibroblast in vitro and in vivo

Unilateral ischemia reperfusion injury (UIRI) with longer ischemia time is associated with an increased risk of acute renal injury and chronic kidney disease. Exosomes can transport lipid, protein, mRNA, and miRNA to corresponding target cells and mediate intercellular information exchange. In this study, we aimed to investigate whether exosome-derived miRNA mediates epithelial-mesenchymal cell communication relevant to renal fibrosis after UIRI. The secretion of exosomes increased remarkably in the kidney after UIRI and in rat renal tubular epithelium cells (NRK-52E) after hypoxia treatment. The inhibition of exosome secretion by Rab27a knockout or GW4869 treatment ameliorates renal fibrosis following UIRI in vivo. Purified exosomes from NRK-52E cells after hypoxia treatment could activate rat kidney fibroblasts (NRK-49F). The inhibition of exosome secretion in hypoxic NRK-52E cells through Rab27a knockdown or GW4869 treatment abolished NRK-49F cell activation. Interestingly, exosomal miRNA array analysis revealed that miR-150-5p expression was increased after hypoxia compared with the control group. The inhibition of exosomal miR-150-5p abolished the ability of hypoxic NRK-52E cells to promote NRK-49F cell activation in vitro, injections of miR-150-5p enriched exosomes from hypoxic NRK-52E cells aggravated renal fibrosis following UIRI, and renal fibrosis after UIRI was alleviated by miR-150-5p-deficient exosome in vivo. Furthermore, tubular cell-derived exosomal miR-150-5p could negatively regulate the expression of suppressor of cytokine signaling 1 to activate fibroblast. Thus, our results suggest that the blockade of exosomal miR-150-5p mediated tubular epithelial cell-fibroblast communication may provide a novel therapeutic target to prevents UIRI progression to renal fibrosis.

Role of autophagy and evaluation the effects of microRNAs 214, 132, 34c and prorenin receptor in a rat model of focal segmental glomerulosclerosis

AIMS

Focal segmental glomerulosclerosis (FSGS) is the common cause of chronic renal disease worldwide. Although there are many etiologic factors which have common theme of podocyte injury conclusive etiology is not clearly understood. In this study, we aimed to explore the role of autophagy in the pathogenesis of podocyte injury, which is the key point in disease progression, and the roles of intrarenal microRNAs and the prorenin receptor (PRR) in the 5/6 nephrectomy and adriamycin nephropathy models of FSGS.

MAIN METHODS

For experimental FSGS model, 5/6 nephrectomy and adriamycin nephropathy models were created and characterized in adult Sprague Dawley rats. Microarray analysis was performed on FSGS and control groups that was confirmed by q-RT-PCR. Beclin1, LC3B, PRR, ATG7 and ATG5 expression were evaluated by western blotting and immunohistochemistry. Also, Beclin1 and PRR expression were measured by ELISA. Glomerular podocyte isolation was performed and autophagic activity was evaluated in podocytes before and after transfection with miRNA mimic and antagonists.

KEY FINDINGS

Glomerular expression of Beclin1, LC3B, PRR, ATG7 and ATG5 were significantly lower in the 5/6 nephrectomy than adriamycin nephropathy group and in both groups lower when compared to control groups. Western blot results were consistent with immunohistochemical data. Electron microscopy revealed signs of impaired autophagy in FSGS. Autophagic activity decreased significantly after miR-214, miR-132 and miR-34c mimics and increased after transfection with antagonists.

SIGNIFICANCE

These results showed that the role of autophagic activity and decreased expression of PRR in FSGS pathogenesis and miR-34c, miR-132 and miR-214 could be a potential treatment strategy by regulating autophagy.

microRNA-199a downregulation alleviates hyperuricemic nephropathy via the PPARγ/β-catenin axis

Hyperuricemia always develops into hyperuricemic nephropathy (HN). The role of microRNA (miR) in HN is less studied. We aimed to discuss the role of miR-199a in HN. The expression of miR-199a and PPARγ in renal tissues of HN rats was detected. The targeting relation between miR-199a and PPARγ was verified. The contents of SCr, UA, BUN, and mALB, renal injury-relevant biomarkers were detected, and the pathological changes of renal tissue and renal interstitial fibrosis were observed by histological staining. After miR-199a and PPARγ knockdown, the contents of SCr, BUN, and mALB and renal interstitial fibrosis were estimated. Collectively, overexpression of miR-199a aggravated the renal injury in HN rats. By contrast, inhibition of miR-199a weakened renal injury, as evidenced by decreased contents of SCr, UA, BUN, and mALB, and mitigated renal interstitial fibrosis. miR-199a targeted PPARγ. Silencing of PPARγ upregulated the levels of downstream genes of β-catenin and the contents of SCr, UA, BUN, and mALB and deteriorated renal interstitial fibrosis. Moreover, the silencing of PPARγ blocked the alleviative effects of miR-199a inhibitor on the renal injury. Overall, miR-199a targets PPARγ and activates the β-catenin pathway, thus aggravating HN, which might provide a future target for the treatment of HN.

Epigenetic Modification Drives Acute Kidney Injury-to-Chronic Kidney Disease Progression

Acute kidney injury (AKI) is a common clinical critical disease. Due to its high morbidity, increasing risk of complications, high mortality rate, and high medical costs, it has become a global concern for human health problems. Initially, researchers believed that kidneys have a strong ability to regenerate and repair, but studies over the past 20 years have found that kidneys damaged by AKI are often incomplete or even unable to repair. Even when serum creatinine returns to baseline levels, renal structural damage persists for a long time, leading to the development of chronic kidney disease (CKD). The mechanism of AKI-to-CKD transition has not been fully elucidated. As an important regulator of gene expression, epigenetic modifications, such as histone modification, DNA methylation, and noncoding RNAs, may play an important role in this process. Alterations in epigenetic modification are induced by hypoxia, thus promoting the expression of inflammatory factor-related genes and collagen secretion. This review elaborated the role of epigenetic modifications in AKI-to-CKD progression, the diagnostic value of epigenetic modifications biomarkers in AKI chronic outcome, and the potential role of targeting epigenetic modifications in the prevention and treatment of AKI to CKD, in order to provide ideas for the subsequent establishment of targeted therapeutic strategies to prevent the progression of renal tubular-interstitial fibrosis.

Evaluation of the severity of nonalcoholic fatty liver disease through analysis of serum exosomal miRNA expression

Noninvasive techniques for evaluating the severity of nonalcoholic fatty liver disease (NAFLD) have shown limited diagnostic performance. MicroRNAs (miRNAs) are useful biomarkers for diagnosing and monitoring the progression and treatment response to several diseases. Here, we evaluated whether serum exosomal miRNAs could be used for the diagnosis and prognosis of NAFLD severity. Exosomal miRNAs were isolated from the sera of 41 patients with NAFLD (diagnosed using liver biopsy) for microarray profiling. The degree of NAFLD severity was determined using inflammation, steatosis, and ballooning scores and the NAFLD activity score (NAS). Correlations between miRNA expression, clinical and biochemical parameters, and mRNA expression were analyzed. Overall, 25, 11, 13, and 14 miRNAs correlated with the inflammation score, steatosis score, ballooning score, and NAS, respectively, with 33 significant correlations observed between 27 miRNAs and six clinical variables. Eight miRNAs (let-7b-5p, miR-378h, -1184, -3613-3p, -877-5p, -602, -133b, and 509-3p) showed anticorrelated patterns with the corresponding mRNA expression. In fibrosis, 52 and 30 interactions corresponding to high miRNA-low mRNA and low miRNA-high mRNA expression, respectively, were observed. The present results therefore suggest that serum exosomal miRNAs can be used to evaluate NAFLD severity and identify potential targets for NAFLD treatment.

Delayed Contralateral Nephrectomy Halted Post-Ischemic Renal Fibrosis Progression and Inhibited the Ischemia-Induced Fibromir Upregulation in Mice

(1) Background: Ischemia reperfusion (IR) is the leading cause of acute kidney injury (AKI) and results in predisposition to chronic kidney disease. We demonstrated that delayed contralateral nephrectomy (Nx) greatly improved the function of the IR-injured kidney and decelerated fibrosis progression. Our aim was to identify microRNAs (miRNA/miR) involved in this process. (2) Methods: NMRI mice were subjected to 30 min of renal IR and one week later to Nx/sham surgery. The experiments were conducted for 7-28 days after IR. On day 8, multiplex renal miRNA profiling was performed. Expression of nine miRNAs was determined with qPCR at all time points. Based on the target prediction, plexin-A2 and Cd2AP were measured by Western blot. (3) Results: On day 8 after IR, the expression of 20/1195 miRNAs doubled, and 9/13 selected miRNAs were upregulated at all time points. Nx reduced the expression of several ischemia-induced pro-fibrotic miRNAs (fibromirs), such as miR-142a-duplex, miR-146a-5p, miR-199a-duplex, miR-214-3p and miR-223-3p, in the injured kidneys at various time points. Plexin-A2 was upregulated by IR on day 10, while Cd2AP was unchanged. (4) Conclusion: Nx delayed fibrosis progression and decreased the expression of ischemia-induced fibromirs. The protein expression of plexin-A2 and Cd2AP is mainly regulated by factors other than miRNAs.

Identification and construction of lncRNA-associated ceRNA network in diabetic kidney disease

Diabetic kidney disease (DKD) has become the major contributor to end-stage renal disease with high incidence and mortality. The functional roles and exact mechanisms of long noncoding RNA (lncRNA)-associated competing endogenous RNA (ceRNA) network in DKD are still largely unknown. This study sought to discover novel potential biomarkers and ceRNA network for DKD.The candidate differentially expressed genes (DEGs), lncRNAs and microRNAs (miRNAs) in human glomerular and tubular tissues derived from Gene Expression Omnibus database were systematically selected and analyzed. Functional enrichment analysis and protein-protein interaction network analysis were conducted to identify hub genes and reveal their regulatory mechanisms involved in DKD. Following this, the integrated ceRNA network was constructed by bioinformatics methods.A total of 164 DEGs, 6 lncRNAs and 18 miRNAs correlated with DKD were finally filtered and identified. It is noteworthy that the global lncRNA-associated ceRNA network related to DKD was constructed, among which lnc-HIST2H2AA4-1, VCAN-AS1 and MAGI2-AS1 were identified as the 3 key lncRNAs, and VCAN, FN1, CCL2, and KNG1 were identified as the predominant genes. Consistent with that observed in the training set, 3 of the key genes also showed significant differences in the 2 validation datasets. Integrating with functional enrichment analysis results, these key genes in the ceRNA network were mainly enriched in the immune and inflammation-related pathways.This study first identified key lncRNAs, miRNAs and their targets, and further revealed a global view of lncRNA-associated ceRNA network involved in DKD by using whole gene transcripts analysis.

Mesenchymal Stem Cells Attenuate Renal Fibrosis via Exosomes-Mediated Delivery of microRNA Let-7i-5p Antagomir

Background

Renal fibrosis is a chronic and progressive process affecting kidneys in chronic kidney disease (CKD). Mesenchymal stem cells-derived exosomes (MSCs-Exo) have been shown to alleviate renal fibrosis and injury, but the mechanism of MSCs-Exo-induced renal protection remains unknown.

Methods

In this study, MSCs were transfected with let-7i-5p antagomir (anti-let-7i-5p), and then exosomes were isolated from the transfected MSCs to deliver anti-let-7i-5p oligonucleotides to inhibit the level of let-7i-5p in kidney tubular epithelial cells (NRK-52E).

Results

In both NRK-52E cells stimulated by TGF-β1 and the mouse kidneys after unilateral ureteral obstruction (UUO), we demonstrated increased level of let-7i-5p. In addition, MSCs-Exo can deliver anti-let-7i-5p to reduce the level of let-7i-5p in NRK-52E cells and increase the expression of its target gene TSC1. Moreover, exosomal anti-let-7i-5p reduced extracellular matrix (ECM) deposition and attenuated epithelial-mesenchymal transition (EMT) process in transforming growth factor beta 1 (TGF-β1)-stimulated NRK-52E cells and in the kidneys of UUO-treated mice. Meanwhile, mice received exosomal anti-let-7i-5p displayed reduced renal fibrosis and improved kidney function when challenged with UUO. Furthermore, exosomal anti-let-7i-5p promoted the activation the tuberous sclerosis complex subunit 1/mammalian target of rapamycin (TSC1/mTOR) signaling pathway in vivo and in vitro.

Conclusion

In conclusion, exosomal anti-let-7i-5p from MSCs exerts anti-fibrotic effects in TGF-β1-induced fibrogenic responses in NRK52E cells in vitro as well as in UUO-induced renal fibrosis model in vivo. These results provided a novel perspective on improving renal fibrosis by MSCs-Exo.

miR-33 in cardiometabolic diseases: lessons learned from novel animal models and approaches

miRNAs have emerged as critical regulators of nearly all biologic processes and important therapeutic targets for numerous diseases. However, despite the tremendous progress that has been made in this field, many misconceptions remain among much of the broader scientific community about the manner in which miRNAs function. In this review, we focus on miR‐33, one of the most extensively studied miRNAs, as an example, to highlight many of the advances that have been made in the miRNA field and the hurdles that must be cleared to promote the development of miRNA‐based therapies. We discuss how the generation of novel animal models and newly developed experimental techniques helped to elucidate the specialized roles of miR‐33 within different tissues and begin to define the specific mechanisms by which miR‐33 contributes to cardiometabolic diseases including obesity and atherosclerosis. This review will summarize what is known about miR‐33 and highlight common obstacles in the miRNA field and then describe recent advances and approaches that have allowed researchers to provide a more complete picture of the specific functions of this miRNA.

Astragalus membranaceus and Salvia miltiorrhiza ameliorates cyclosporin A-induced chronic nephrotoxicity through the "gut-kidney axis"

ETHNOPHARMACOLOGICAL RELEVANCE

The combination of Astragalus membranaceus and Salvia miltiorrhiza (AS) is an effective prescription that is widely used to treat chronic kidney disease (CKD) clinically in traditional Chinese medicine. Our previous studies have shown that AS can alleviate early CKD through the "gut-kidney axis", but the regulatory role of AS in the "gut-kidney axis" in the middle and late stages of CKD caused by cyclosporin A-induced chronic nephrotoxicity (CICN) has remained unclear.

AIM OF THE STUDY

To explore the protective effect of AS by regulating the intestinal flora to further control the miRNA-mRNA interaction profiles in CICN.

MATERIALS AND METHODS

Thirty-two mice were divided into four groups: Normal (N) (olive oil), Model (M) (CsA, 30 mg kg-1 d-1), AS (CsA + AS, 30 + 8.4 g kg-1 d-1) and FMT-AS (CsA + Faeces of AS group, 30 mg + 10 mL kg-1 d-1). The mice were treated for 6 weeks. Changes in renal function related metabolites were detected, pathological changes in the colon and kidney were observed, and 16S rDNA sequencing was performed on mouse faeces. In addition, miRNA and mRNA sequencing were performed on the kidney to construct differential expression (DE) profiles of the other 3 groups compared with group M. The target mRNAs among the DE miRNAs were then predicted, and an integrated analysis was performed with the DE mRNAs to annotate gene function by KEGG. DE miRNAs and DE mRNAs related to CICN in the overlapping top 20 KEGG pathways were screened and verified.

RESULTS

Eight metabolites that could worsen renal function were increased in group M, accompanied by thickening of the glomerular basement membrane, vacuolar degeneration of renal tubules, and proliferation of collagen fibres, while AS and FMT-AS intervention amended these changes to varying degrees. Simultaneously, intestinal permeability increased, the abundance and diversity of the flora decreased, and the ratio of Firmicum to Bacteroides (F/B) increased in group M. The AS and FMT-AS treatments reversed the flora disorder and increased probiotics producing butyric acid and lactic acid, especially Akkermansia and Lactobacillus, which might regulate the 12 overlapping top 20 KEGG pathways, such as Butanoate metabolism, Tryptophan metabolism and several RF-related pathways, leading to the remission of renal metabolism. Finally, 15 DE miRNAs and 45 DE mRNAs were screened as the therapeutic targets, and the results coincided with the sequencing results.

CONCLUSION

AS could alleviate renal fibrosis and metabolism caused by CICN through the "gut-kidney axis". Probiotics such as Akkermansia and Lactobacillus were the primary driving factors, and the miRNA-mRNA interaction profiles, especially Butanoate metabolism and Tryptophan metabolism, may be an important subsequent response and regulatory mechanism.

Oligonucleotide-Based Therapies for Renal Diseases

The global burden of chronic kidney disease (CKD) is increasing every year and represents a great cost for public healthcare systems, as the majority of these diseases are progressive. Therefore, there is an urgent need to develop new therapies. Oligonucleotide-based drugs are emerging as novel and promising alternatives to traditional drugs. Their expansion corresponds with new knowledge regarding the molecular basis underlying CKD, and they are already showing encouraging preclinical results, with two candidates being evaluated in clinical trials. However, despite recent technological advances, efficient kidney delivery remains challenging, and the presence of off-targets and side-effects precludes development and translation to the clinic. In this review, we provide an overview of the various oligotherapeutic strategies used preclinically, emphasizing the most recent findings in the field, together with the different strategies employed to achieve proper kidney delivery. The use of different nanotechnological platforms, including nanocarriers, nanoparticles, viral vectors or aptamers, and their potential for the development of more specific and effective treatments is also outlined.

MicroRNA-363-3p Inhibits the Expression of Renal Fibrosis Markers in TGF-β1-Treated HK-2 Cells by Targeting TGF-β2

This study aimed to explore the role of miR-363-3p in renal fibrosis (RF) in vitro. HK-2 cells were treated with transforming growth factor (TGF)-β1 for 72 h to establish an in vitro model of RF. Subsequently, western blot analysis and reverse transcription-quantitative PCR were used to detect the protein and mRNA expression levels of RF markers in TGF-β1-treated HK-2 cells, respectively. The results showed that the protein and mRNA expression levels of TGF-β2, α-smooth muscle actin (SMA), fibronectin, vimentin, collagen II and N-cadherin were increased, while the protein and mRNA expression levels of E-cadherin were decreased in TGF-β1-treated HK-2 cells. The level of miR-363-3p was significantly decreased in TGF-β1-treated HK-2 cells. TargetScan indicated that TGF-β2 was a direct target gene for miR-363-3p, which was further verified using dual luciferase reporter gene assays. Further analyses revealed that the increased protein and mRNA expression levels of TGF-β2, α-SMA, fibronectin, vimentin, collagen II, N-cadherin, increased phosphorylated-Smad3 protein level, and decreased E-cadherin protein and mRNA expression in TGF-β1-treated HK-2 cells were significantly reversed by miR-363-3p mimics. However, all the effects were suppressed by a TGF-β2-plasmid. The results suggested that miR-363-3p plays a protective role in RF by regulating the TGF-β2/Smad3 signaling pathway.

Molecular and functional profiling of apical versus basolateral small extracellular vesicles derived from primary human proximal tubular epithelial cells under inflammatory conditions

Proximal tubular epithelial cells (PTEC) are central players in inflammatory kidney diseases. However, the complex signalling mechanism/s via which polarized PTEC mediate disease progression are poorly understood. Small extracellular vesicles (sEV), including exosomes, are recognized as fundamental components of cellular communication and signalling courtesy of their molecular cargo (lipids, microRNA, proteins). In this study, we examined the molecular content and function of sEV secreted from the apical versus basolateral surfaces of polarized human primary PTEC under inflammatory diseased conditions. PTEC were cultured under normal and inflammatory conditions on Transwell inserts to enable separate collection and isolation of apical/basolateral sEV. Significantly increased numbers of apical and basolateral sEV were secreted under inflammatory conditions compared with equivalent normal conditions. Multi‐omics analysis revealed distinct molecular profiles (lipids, microRNA, proteins) between inflammatory and normal conditions for both apical and basolateral sEV. Biological pathway analyses of significantly differentially expressed molecules associated apical inflammatory sEV with processes of cell survival and immunological disease, while basolateral inflammatory sEV were linked to pathways of immune cell trafficking and cell‐to‐cell signalling. In line with this mechanistic concept, functional assays demonstrated significantly increased production of chemokines (monocyte chemoattractant protein‐1, interleukin‐8) and immuno‐regulatory cytokine interleukin‐10 by peripheral blood mononuclear cells activated with basolateral sEV derived from inflammatory PTEC. We propose that the distinct molecular composition of sEV released from the apical versus basolateral membranes of human inflammatory PTEC may reflect specialized functional roles, with basolateral‐derived sEV pivotal in modulating tubulointerstitial inflammatory responses observed in many immune‐mediated kidney diseases. These findings provide a rationale to further evaluate these sEV‐mediated inflammatory pathways as targets for biomarker and therapeutic development.

Epigenetic modifications of Klotho expression in kidney diseases

Developments of many renal diseases are substantially influenced by epigenetic modifications of numerous genes, mainly mediated by DNA methylations, histone modifications, and microRNA interference; however, not all gene modifications causally affect the disease onset or progression. Klotho is a critical gene whose repressions in various pathological conditions reportedly involve epigenetic regulatory mechanisms. Klotho is almost unexceptionally repressed early after acute or chronic renal injuries and its levels inversely correlated with the disease progression and severity. Moreover, the strategies of Klotho derepression via epigenetic modulations beneficially change the pathological courses both in vitro and in vivo. Hence, Klotho is not only considered a biomarker of the renal disease but also a potential or even an ideal target of therapeutic epigenetic intervention. Here, we summarize and discuss studies that investigate the Klotho repression and intervention in renal diseases from an epigenetic point of view. These information might shed new sights into the effective therapeutic strategies to prevent and treat various renal disorders.

miRNAs as attractive diagnostic and therapeutic targets for Familial Mediterranean Fever

Familial Mediterranean Fever (FMF) is a hereditary early-onset disease that causes periodical fever attack, excessive release of IL-1β, serositis, arthritis and peritonitis. Genetic analyses conducted on FMF patients (mutated and non-mutated) have highlighted that additional contributing factors such as epigenetics and environment play a role in clinical manifestations of FMF. Recently researchers report that microRNAs (miRNAs), implicated in epigenetic mechanisms, may contribute to the pathogenesis of FMF. miRNAs, a member of the captivating noncoding RNA family, are the single-strand transcripts that work in physiological and pathophysiological processes by regulating target gene expression. Recent studies have shown that miRNAs are associated with various mechanisms involved in the pathogenesis of FMF, such as apoptosis, inflammation and autophagy. Moreover, these miRNAs molecules might have potential use in treatment, therapeutic response monitoring and the diagnosis of subtypes of the disease in the future. Motivated by these potential benefits (diagnostic and therapeutic) of miRNAs, we focus on recent advances of clinical significances and potential action mechanisms of miRNAs in FMF pathogenesis and discuss their potential use for FMF.

MiR-27b-3p inhibits the progression of renal fibrosis via suppressing STAT1

Renal fibrosis is a pathologic change in chronic kidney disease (CKD). MicroRNAs (miRNAs) have been shown to play an important role in the development of renal fibrosis. However, the biological role of miR-27b-3p in renal fibrosis remains unclear. Thus, this study aimed to investigate the role of miR-27b-3p in the progression of renal fibrosis. In this study, HK-2 cells were stimulated with transforming growth factor (TGF)-β1 for mimicking fibrosis progression in vitro. The unilateral ureteric obstruction (UUO)-induced mice renal fibrosis in vivo was established as well. The results indicated that the overexpression of miR-27b-3p significantly inhibited epithelial-to-mesenchymal transition (EMT) in TGF-β1-stimulated HK-2 cells, as shown by the decreased expressions of α-SMA, collagen III, Fibronectin and Vimentin. In addition, overexpression of miR-27b-3p markedly decreased TGF-β1-induced apoptosis in HK-2 cells, as evidenced by the decreased levels of Fas, active caspase 8 and active caspase 3. Meanwhile, dual-luciferase assay showed that miR-27b-3p downregulated signal transducers and activators of transcription 1 (STAT1) expression through direct binding with the 3′-UTR of STAT1. Furthermore, overexpression of miR-27b-3p attenuated UUO-induced renal fibrosis via downregulation of STAT1, α-SMA and collagen III. In conclusion, miR-27b-3p overexpression could alleviate renal fibrosis via suppressing STAT1 in vivo and in vitro. Therefore, miR-27b-3p might be a promising therapeutic target for the treatment of renal fibrosis.

Role of γ-adducin in actin cytoskeleton rearrangements in podocyte pathophysiology

We recently reported that the enhanced susceptibility to chronic kidney disease (CKD) in the fawn-hooded hypertensive (FHH) rat is caused, at least in part, by a mutation in γ-adducin (ADD3) that attenuates renal vascular function. The present study explored whether Add3 contributes to the modulation of podocyte structure and function using FHH and FHH.Add3 transgenic rats. The expression of ADD3 on the membrane of primary podocytes isolated from FHH was reduced compared with FHH.Add3 transgenic rats. We found that F-actin nets, which are typically localized in the lamellipodia, replaced unbranched stress fibers in conditionally immortalized mouse podocytes transfected with Add3 Dicer-substrate short interfering RNA (DsiRNA) and primary podocytes isolated from FHH rats. There were increased F/G-actin ratios and expression of the Arp2/3 complexes throughout FHH podocytes in association with reduced synaptopodin and RhoA but enhanced Rac1 and CDC42 expression in the renal cortex, glomeruli, and podocytes of FHH rats. The expression of nephrin at the slit diaphragm and the levels of focal adhesion proteins integrin-α3 and integrin-β1 were decreased in the glomeruli of FHH rats. Cell migration was enhanced and adhesion was reduced in podocytes of FHH rats as well as in immortalized mouse podocytes transfected with Add3 DsiRNA. Mean arterial pressures were similar in FHH and FHH.Add3 transgenic rats at 16 wk of age; however, FHH rats exhibited enhanced proteinuria associated with podocyte foot process effacement. These results demonstrate that reduced ADD3 function in FHH rats alters baseline podocyte pathophysiology by rearrangement of the actin cytoskeleton at the onset of proteinuria in young animals.

New Potential Biomarkers for Chronic Kidney Disease Management-A Review of the Literature

The prevalence of chronic kidney disease (CKD) is increasing worldwide, and the mortality rate continues to be unacceptably high. The biomarkers currently used in clinical practice are considered relevant when there is already significant renal impairment compromising the early use of potentially successful therapeutic interventions. More sensitive and specific biomarkers to detect CKD earlier on and improve patients' prognoses are an important unmet medical need. The aim of this review is to summarize the recent literature on new promising early CKD biomarkers of renal function, tubular lesions, endothelial dysfunction and inflammation, and on the auspicious findings from metabolomic studies in this field. Most of the studied biomarkers require further validation in large studies and in a broad range of populations in order to be implemented into routine CKD management. A panel of biomarkers, including earlier biomarkers of renal damage, seems to be a reasonable approach to be applied in clinical practice to allow earlier diagnosis and better disease characterization based on the underlying etiologic process.

Cross-Kingdom Regulation by Plant microRNAs Provides Novel Insight into Gene Regulation

microRNAs (miRNAs) are well known as major players in mammalian and plant genetic systems that act by regulating gene expression at the post-transcriptional level. These tiny molecules can regulate target genes (mRNAs) through either cleavage or translational inhibition. Recently, the discovery of plant-derived miRNAs showing cross-kingdom abilities to regulate mammalian gene expression has prompted exciting discussions among researchers. After being acquired orally through the diet, plant miRNAs can survive in the digestive tract, enter the circulatory system, and regulate endogenous mRNAs. Here, we review current knowledge regarding the cross-kingdom mechanisms of plant miRNAs, related controversies, and potential applications of these miRNAs in dietary therapy, which will provide new insights for plant miRNA investigations related to health issues in humans.

Caloric restriction alleviates aging-related fibrosis of kidney through downregulation of miR-21 in extracellular vesicles

Glomerulosclerosis and renal interstitial fibrosis occur with the aging kidney. In this study, we examined the expression of miR-21, peroxisome proliferator-activated receptor(PPARα), hypoxia-inducible factor(HIF-1α) in the kidney of 3-month-old rats fed ad libitum (YAL), 24-month-old rats fed ad libitum (OAL) and 24-month-old rats subjected to a 70% calorie-restricted diet for 8 months (OCR). We found long-term caloric restriction (CR) ameliorated aging and aging-related fibrosis. CR ameliorated the increment of miR-21 and HIF-1α, as well as the decrement of PPARα in old ad libitum group. Human proximal tubular cells (HPTCs) presented phenotypes of senescence and epithelial to mesenchymal transition (EMT) under high-glucose conditions, in which senescence occurred earlier than EMT. Senescent cells secreted extracellular vesicles (EVs) which contained miR-21 into the recipient cells. Inhibiting miR-21 of donor cells prevented the occurrence of EMT in recipient cells. In addition, miR-21 induced EMT through targeting PPARα protein and consequently enhancing HIF-1α expression, although other pathways cannot be ruled out. These findings demonstrated that miR-21-containing EVs derived from the senescent cells could facilitate EMT of HPTCs via PPARα-HIF-1α signaling pathway. Long-term caloric restriction and caloric restriction mimetics alleviated aging-related-fibrosis of kidney through downregulation of miR-21.

Upregulation of miRNA-1228-3p alleviates TGF-β-induced fibrosis in renal tubular epithelial cells

BACKGROUND

Chronic kidney disease (CKD) has become a major public health issue, which can lead to renal fibrosis regardless of the initial injury. It has been previously reported that miRNA-1228-3p was correlate with the progression of kidney fibrosis. However, the mechanism by which miRNA-1228-3p regulates renal fibrosis remains unclear.

METHODS

Renal tubular epithelial cells (HK-2) were treated with TGF-β1 (10 ng/ml) in an in vitro model of renal fibrosis. Gene and protein expressions in HK-2 cells were measured by Western-blot and RT-qPCR, respectively. The relation between miRNA-1228-3p and its target gene was investigated by dual luciferase report analysis.

RESULTS

Upregulation of miRNA-1228-3p significantly inhibited TGF-β1-induced fibrosis of HK-2 cells in vitro by targeting GDF11. In addition, miRNA-1228-3p exhibited anti-fibrosis effect through inhibition of the smad2/smad4 signaling pathway.

CONCLUSION

Upregulation of miRNA-1228-3p markedly inhibited the progression of renal fibrosis in vitro, indicating that miRNA-1228-3p may serve as a potential novel target for the treatment of renal fibrosis.

Down-regulation of LINC00667 hinders renal tubular epithelial cell apoptosis and fibrosis through miR-34c

PURPOSE

This study aimed to down-regulate LINC00667 and inhibit apoptosis and fibrosis of renal tubular epithelial cells through miR-34c.

METHODS

Altogether, 98 patients with chronic kidney disease treated in our hospital were selected as the study group, and 67 normal people were selected as the control group. Epithelial cells of proximal convoluted tubules in human renal cortex were purchased. TGF-β1 was used to induce fibrosis of HK-2 renal tubular epithelial cells. The expression of LINC00667, miR-34c, type I collagen (Col 1) and type III collagen (Col 3) were detected by qRT-PCR and WB.

RESULTS

LINC00667 was highly expressed in cancer tissues and HK-2, while miR-34c was poorly expressed. Inhibition of LINC00667 and over-expression of miR-34c could inhibit the proliferation and invasion of chronic kidney disease cells, but increase the apoptosis rate. Down-regulation of LINC00667 could significantly reduce of Col 1 and Col 3 in renal interstitial fibroblasts induced by TGF-β1, while up-regulation of miR-34c could also achieve this effect. Double luciferase report confirmed that there was a targeted regulatory relationship between LINC00667 and miR-34c.

CONCLUSION

LINC00667 could reduce the proliferation and invasion of chronic kidney disease cells, increase the apoptosis rate by regulating miR-34c, and improve renal fibrosis.