MicroRNA-26a inhibits TGF-β-induced extracellular matrix protein expression in podocytes by targeting CTGF and is downregulated in diabetic nephropathy

MicroRNA-26a deficiency attenuates the severity of frozen shoulder in a mouse immobilization model

The main pathogenesis of the frozen shoulder is thought to be the inflammation of the intra-articular synovium and subsequent fibrosis of the shoulder joint capsule. However, the molecular pathogenesis of the frozen shoulder is still unknown. A class of noncoding RNAs, microRNAs contribute to various diseases including musculoskeletal diseases. MicroRNA-26a (miR-26a) has been reported to be associated with fibrosis in several organs. This study aims to reveal the role of miR-26a on fibrosis in the shoulder capsule using a frozen shoulder model in miR-26a deficient (miR-26a KO) mice. MiR-26a KO and wild-type (WT) mice were investigated using a frozen shoulder model. The range of motion (ROM) of the shoulder, histopathological changes such as synovitis, and fibrosis-related gene expression in the model mice were evaluated to determine the role of miR-26a. In WT mice, both inflammatory cell infiltration and thickening of the inferior shoulder joint capsule were observed after 1 week of immobilization, and this thickening further progressed over the subsequent 6 weeks. However, the immobilized shoulder in miR-26a KO mice consistently exhibited significantly better ROM compared with WT mice at 1 and 6 weeks, and histological changes were significantly less severe. The expression of inflammation- and fibrosis-related genes was decreased in the miR-26a KO mice compared with WT mice at 1 and 6 weeks. Together, miR-26a deficiency attenuated the severity of frozen shoulder in the immobilization model mouse. The present study suggests that miR-26a has the potential to be a target miRNA for therapeutic approach to frozen shoulder.

Urinary podocyte markers in diabetic kidney disease

Podocytes are involved in maintaining kidney function and are a major focus of research on diabetic kidney disease (DKD). Urinary biomarkers derived from podocyte fragments and molecules have been proposed for the diagnosis and monitoring of DKD. Various methods have been used to detect intact podocytes and podocyte-derived microvesicles in urine, including centrifugation, visualization, and molecular quantification. Quantification of podocyte-specific protein targets and messenger RNA levels can be performed by Western blotting or enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. At present, many of these techniques are expensive and labor-intensive, all limiting their widespread use in routine clinical tests. While the potential of urinary podocyte markers for monitoring and risk stratification of DKD has been explored, systematic studies and external validation are lacking in the current literature. Standardization and automation of laboratory methods should be a priority for future research, and the added value of these methods to routine clinical tests should be defined.

Deciphering the role of MicroRNAs in diabetic nephropathy: Regulatory mechanisms and molecular insights

A serious consequence of diabetes mellitus, diabetic nephropathy (DN) which causes gradual damage to the kidneys. Dietary changes, blood pressure control, glucose control, and hyperlipidemia are all important components of DN management. New research, however, points to microRNAs (miRNAs) as having a pivotal role in DN pathogenesis. Miniature non-coding RNA molecules such as miRNAs control gene expression and impact several biological processes. The canonical and non-canonical routes of miRNA biogenesis are discussed in this article. In addition, several important signaling pathways are examined in the study of miRNA regulation in DN. A deeper knowledge of these regulatory mechanisms would allow for a better understanding of the molecular basis of DN and the development of innovative therapeutic strategies. Finally, miRNAs show tremendous potential as DN diagnostic biomarkers and treatment targets, opening up promising avenues for further study and potential clinical use.

[The Role of TGF-β1/SMAD in Diabetic Nephropathy: Mechanisms and Research Development]

Diabetic nephropathy (DN) is a common complication of diabetes and a leading cause of end-stage renal disease. Transforming growth factor-β1 (TGF-β1)/SMAD signaling activation plays an important role in the onset and progression of DN. Reported findings suggest that the activation of TGF-β1 (including the latent form, the active form, and the receptors) and its downstream signaling proteins (SMAD3, SMAD7, etc.) plays a critical role in DN. In addition, TGF-β1/SMAD signaling may mediate the pathogenesis and progression of DN via various microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Emerging evidence shows that TGF-β1, SMAD3, and SMAD7 are the main signaling proteins that contribute to the development of DN, and that they can be potential targets for the treatment of DN. However, recent clinical trials have shown that the anti-TGF-β1 monoclonal antibody treatment fails to effectively alleviate DN, which suggests that upstream inhibition of TGF-β1/SMAD signaling does not alleviate clinical symptoms and that this may be related to the fact that TGF-β1/SMAD has multiple biological effects. Targeted inhibition of the downstream TGF-β1 signaling (e.g., SMAD3 and SMAD7) may be an effective approach to attenuate DN. This article discussed the current understanding of the molecular mechanisms and potential targets for the treatment and prevention of DN by focusing on TGF-β1/SMAD signaling.

Dual deletion of guanylyl cyclase-A and p38 mitogen-activated protein kinase in podocytes with aldosterone administration causes glomerular intra-capillary thrombi

Natriuretic peptides exert not only blood-lowering but also kidney-protective effects through guanylyl cyclase-A (GC-A), a natriuretic peptide receptor. Signaling through GC-A has been shown to protect podocytes from aldosterone-induced glomerular injury, and a p38 mitogen-activated protein kinase (MAPK) inhibitor reduced glomerular injury in aldosterone-infused podocyte-specific GC-A knockout mice. To explore the role of p38 MAPK in podocytes, we constructed podocyte-specific p38 MAPK and GC-A double knockout mice (pod-double knockout mice). Unexpectedly, aldosterone-infused and high salt-fed (B-ALDO)-treated pod-double knockout mice resulted in elevated serum creatinine, massive albuminuria, macrophage infiltration, foot process effacement, nephrin and podocin reduction, and additionally, intra-capillary fibrin thrombi, indicating endothelial injury. Microarray analysis showed increased plasminogen activator inhibitor-1 (PAI-1) in glomeruli of B-ALDO-treated pod-double knockout mice. In B-ALDO-treated pod-double knockout mice, PAI-1 increased in podocytes, and treatment with PAI-1 neutralizing antibody ameliorated intra-capillary thrombus formation. In vitro, deletion of p38 MAPK by the CRISPR/Cas9 system and knockdown of GC-A in human cultured podocytes upregulated PAI-1 and transforming growth factor- β1 (TGF-β1). When p38 MAPK knockout podocytes, transfected with a small interfering RNA to suppress GC-A, were co-cultured with glomerular endothelial cells in a transwell system, the expression of TGF-β1 was increased in glomerular endothelial cells. PAI-1 inhibition ameliorated both podocyte and endothelial injury in the transwell system signifying elevated PAI-1 in podocytes is a factor disrupting normal podocyte-endothelial crosstalk. Thus, our results indicate that genetic dual deletion of p38 MAPK and GC-A in podocytes accelerates both podocyte and endothelial injuries, suggesting these two molecules play indispensable roles in podocyte function.

Capturing the Kidney Transcriptome by Urinary Extracellular Vesicles-From Pre-Analytical Obstacles to Biomarker Research

Urinary extracellular vesicles (uEV) hold non-invasive RNA biomarkers for genitourinary tract diseases. However, missing knowledge about reference genes and effects of preanalytical choices hinder biomarker studies. We aimed to assess how preanalytical variables (urine storage temperature, isolation workflow) affect diabetic kidney disease (DKD)-linked miRNAs or kidney-linked miRNAs and mRNAs (kidney-RNAs) in uEV isolates and to discover stable reference mRNAs across diverse uEV datasets. We studied nine raw and normalized sequencing datasets including healthy controls and individuals with prostate cancer or type 1 diabetes with or without albuminuria. We focused on kidney-RNAs reviewing literature for DKD-linked miRNAs from kidney tissue, cell culture and uEV/urine experiments. RNAs were analyzed by expression heatmaps, hierarchical clustering and selecting stable mRNAs with normalized counts (>200) and minimal coefficient of variation. Kidney-RNAs were decreased after urine storage at -20 °C vs. -80 °C. Isolation workflows captured kidney-RNAs with different efficiencies. Ultracentrifugation captured DKD -linked miRNAs that separated healthy and diabetic macroalbuminuria groups. Eleven mRNAs were stably expressed across the datasets. Hence, pre-analytical choices had variable effects on kidney-RNAs-analyzing kidney-RNAs complemented global correlation, which could fade differences in some relevant RNAs. Replicating prior DKD-marker results and discovery of candidate reference mRNAs encourages further uEV biomarker studies.

Rab3A/Rab27A System Silencing Ameliorates High Glucose-Induced Injury in Podocytes

Diabetic nephropathy is a major complication in diabetic patients. Podocytes undergo loss and detachment from the basal membrane. Intra- and intercellular communication through exosomes are key processes for maintaining function, and the Rab3A/Rab27A system is an important counterpart. Previously, we observed significant changes in the Rab3A/Rab27A system in podocytes under glucose overload, demonstrating its important role in podocyte injury. We investigated the implication of silencing the Rab3A/Rab27A system in high glucose-treated podocytes and analysed the effect on differentiation, apoptosis, cytoskeletal organisation, vesicle distribution, and microRNA expression in cells and exosomes. For this, we subjected podocytes to high glucose and transfection through siRNAs, and we isolated extracellular vesicles and performed western blotting, transmission electron microscopy, RT-qPCR, immunofluorescence and flow cytometry assays. We found that silencing RAB3A and RAB27A generally leads to a decrease in podocyte differentiation and cytoskeleton organization and an increase in apoptosis. Moreover, CD63-positive vesicles experienced a pattern distribution change. Under high glucose, Rab3A/Rab27A silencing ameliorates some of these detrimental processes, suggesting a differential influence depending on the presence or absence of cellular stress. We also observed substantial expression changes in miRNAs that were relevant in diabetic nephropathy upon silencing and glucose treatment. Our findings highlight the Rab3A/Rab27A system as a key participant in podocyte injury and vesicular traffic regulation in diabetic nephropathy.

Characterizing Intraindividual Podocyte Morphology In Vitro with Different Innovative Microscopic and Spectroscopic Techniques

Podocytes are critical components of the glomerular filtration barrier, sitting on the outside of the glomerular basement membrane. Primary and secondary foot processes are characteristic for podocytes, but cell processes that develop in culture were not studied much in the past. Moreover, protocols for diverse visualization methods mostly can only be used for one technique, due to differences in fixation, drying and handling. However, we detected by single-cell RNA sequencing (scRNAseq) analysis that cells reveal high variability in genes involved in cell type-specific morphology, even within one cell culture dish, highlighting the need for a compatible protocol that allows measuring the same cell with different methods. Here, we developed a new serial and correlative approach by using a combination of a wide variety of microscopic and spectroscopic techniques in the same cell for a better understanding of podocyte morphology. In detail, the protocol allowed for the sequential analysis of identical cells with light microscopy (LM), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Skipping the fixation and drying process, the protocol was also compatible with scanning ion-conductance microscopy (SICM), allowing the determination of podocyte surface topography of nanometer-range in living cells. With the help of nanoGPS Oxyo^®, tracking concordant regions of interest of untreated podocytes and podocytes stressed with TGF-β were analyzed with LM, SEM, Raman spectroscopy, AFM and SICM, and revealed significant morphological alterations, including retraction of podocyte process, changes in cell surface morphology and loss of cell-cell contacts, as well as variations in lipid and protein content in TGF-β treated cells. The combination of these consecutive techniques on the same cells provides a comprehensive understanding of podocyte morphology. Additionally, the results can also be used to train automated intelligence networks to predict various outcomes related to podocyte injury in the future.

What do we actually know about exosomal microRNAs in kidney diseases?

There are several types of kidney diseases with complex causes. If left untreated, these diseases irreversibly progress to end-stage renal disease. Thus, their early diagnosis and targeted treatment are important. Exosomes-extracellular vesicles released by a variety of cells-are ideal carriers for DNA, RNA, proteins, and other metabolites owing to their bilayer membranes. Studies have shown that almost all renal cells can secrete exosomes. While research on exosomal microRNAs in the context of renal diseases begun only recently, rapid progress has been achieved. This review summarizes the changes in exosomal microRNA expression in different kidney diseases. Thus, it highlights the diagnostic and prognostic value of these exosomal microRNAs. Further, this review analyzes their roles in the development of different kidney diseases, guiding research on molecular mechanisms and therapeutic strategies.

MiR-18a-5p Targets Connective Tissue Growth Factor Expression and Inhibits Transforming Growth Factor β2-Induced Trabecular Meshwork Cell Contractility

Increased trabecular meshwork (TM) cell and tissue contractility is a driver of the reduced outflow facility and elevation of intraocular pressure (IOP) associated with primary open-angle glaucoma (POAG). Connective tissue growth factor (CTGF) is an established mediator of TM cell contractility, and its expression is increased in POAG due to transforming growth factor β 2 (TGFβ2) signalling. Inhibiting CTGF upregulation using microRNA (miRNA) mimetics could represent a new treatment option for POAG. A combination of in silico predictive tools and a literature review identified a panel of putative CTGF-targeting miRNAs. Treatment of primary human TM cells with 5 ng/mL TGFβ2 for 24 h identified miR-18a-5p as a consistent responder, being upregulated in cells from five different human donors. Transfection of primary donor TM cells with 20 nM synthetic miR-18a-5p mimic reduced TGFβ2-induced CTGF protein expression, and stable lentiviral-mediated overexpression of this miRNA reduced TGFβ2-induced contraction of collagen gels. Together, these findings identify miR-18a-5p as a mediator of the TGFβ2 response and a candidate therapeutic agent for glaucoma via its ability to inhibit CTGF-associated increased TM contractility.

MicroRNAs in kidney injury and disease

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by degrading or repressing the translation of their target messenger RNAs. As miRNAs are critical regulators of cellular homeostasis, their dysregulation is a crucial component of cell and organ injury. A substantial body of evidence indicates that miRNAs are involved in the pathophysiology of acute kidney injury (AKI), chronic kidney disease and allograft damage. Different subsets of miRNAs are dysregulated during AKI, chronic kidney disease and allograft rejection, which could reflect differences in the physiopathology of these conditions. miRNAs that have been investigated in AKI include miR-21, which has an anti-apoptotic role, and miR-214 and miR-668, which regulate mitochondrial dynamics. Various miRNAs are downregulated in diabetic kidney disease, including the miR-30 family and miR-146a, which protect against inflammation and fibrosis. Other miRNAs such as miR-193 and miR-92a induce podocyte dedifferentiation in glomerulonephritis. In transplantation, miRNAs have been implicated in allograft rejection and injury. Further work is needed to identify and validate miRNAs as biomarkers of graft function and of kidney disease development and progression. Use of combinations of miRNAs together with other molecular markers could potentially improve diagnostic or predictive power and facilitate clinical translation. In addition, targeting specific miRNAs at different stages of disease could be a promising therapeutic strategy.

Adult Wilms Tumor: Genetic Evidence of Origin of a Subset of Cases From Metanephric Adenoma

The genetics of nephroblastoma (Wilms tumor) occurring in adults is largely unknown, as studies have largely been limited to isolated case reports. We, therefore, studied 14 adult Wilms tumors for genetic alterations, using expanded targeted sequencing on 11 cases. The patients ranged from 17 to 46 years of age (mean and median, 31 y), and there were 8 males and 6 females. Five Wilms tumors harbored BRAF V600E mutations. All of these had better-differentiated areas identical to metanephric adenoma, as has previously been described. In 3 such cases, microdissection studies revealed that the BRAF V600E mutation was present in both the metanephric adenoma and Wilms tumor areas; however, additional genetic alterations (including TERT promoter mutations in 2 cases, ASLX1/ATR mutations in 1 other case) were limited to the Wilms tumor component. These findings suggest that the Wilms tumor developed from the metanephric adenoma. Other adult Wilms tumors harbored genetic alterations previously reported in the more common pediatric Wilms tumors, including WT1 mutations (2 cases), ASLX1 mutations (3 additional cases), NSD2 mutation (1 additional case), and 11p loss (3 cases). In summary, a significant subset of adult Wilms tumors (specifically those of epithelial type with differentiated areas) harbor targetable BRAF V600E mutations and appear to arise from metanephric adenomas as a consequence of additional acquired genetic alterations. Other adult Wilms tumors often harbor genetic alterations found in their more common pediatric counterparts, suggesting at least some similarities in their pathogenesis.

Dexmedetomidine Protects Against Kidney Fibrosis in Diabetic Mice by Targeting miR-101-3p-Mediated EndMT

Objective: Our main purpose is to explore the effect and mechanism of Dexmedetomidine (DEX)  in diabetic nephropathy fibrosis.

Methods: Diabetic model was established by intraperitoneal injection of streptozotocin (STZ) treated CD-1 mice and high glucose cultured human dermal microvascular endothelial cells (HMVECs). Immunofluorescence was used to detect renal endothelial-mesenchymal transition (EndMT); Hematoxylin and Eosin (HE) staining and Masson’s Trichrome Staining (MTS) was used to analyze renal fibrosis; CCK-8 was used to evaluate cell viability; Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to assess the expression of miR-101-3p; Western blots were utilized to judge the protein expression levels of EndMT, extracellular matrix and TGF-β1/Smad3 signal pathway.

Results: In this study, we first found that the protective effect of DEX on DN was related to EndMT. DEX alleviated kidney fibrosis by inhibiting EndMT in diabetic CD-1 mice. DEX could also inhibit high glucose-induced HMVECs EndMT. Then, we confirmed that miR-101-3p was the regulatory target of DEX. The expression of miR-101-3p was decreased in diabetic CD-1 mice and high glucose-induced HMVECs. After DEX treatment, the miR-101-3p increased, and the inhibition of miR-101-3p could counteract the protective effect of DEX and aggravate the EndMT. Finally, we found that the TGF- β1/Smad3 signal pathway was involved in the protective effect of DEX on DN. DEX inhibited the activation of TGF-β1/Smad3 signal pathway. On the contrary, inhibiting miR-101-3p promoted the expression of TGF-β1/Smad3.

Conclusion: DEX protects kidney fibrosis in diabetic mice by targeting miR-101-3p-mediated EndMT.

Kidney microRNA Expression Pattern in Type 2 Diabetic Nephropathy in BTBR Ob/Ob Mice

Diabetic nephropathy (DN) is the main leading cause of chronic kidney disease worldwide. Although remarkable therapeutic advances have been made during the last few years, there still exists a high residual risk of disease progression to end-stage renal failure. To further understand the pathogenesis of tissue injury in this disease, by means of the Next-Generation Sequencing, we have studied the microRNA (miRNA) differential expression pattern in kidneys of Black and Tan Brachyury (BTBR) ob/ob (leptin deficiency mutation) mouse. This experimental model of type 2 diabetes and obesity recapitulates the key histopathological features described in advanced human DN and therefore can provide potential useful translational information. The miRNA-seq analysis, performed in the renal cortex of 22-week-old BTBR ob/ob mice, pointed out a set of 99 miRNAs significantly increased compared to non-diabetic, non-obese control mice of the same age, whereas no miRNAs were significantly decreased. Among them, miR-802, miR-34a, miR-132, miR-101a, and mir-379 were the most upregulated ones in diabetic kidneys. The in silico prediction of potential targets for the 99 miRNAs highlighted inflammatory and immune processes, as the most relevant pathways, emphasizing the importance of inflammation in the pathogenesis of kidney damage associated to diabetes. Other identified top canonical pathways were adipogenesis (related with ectopic fatty accumulation), necroptosis (an inflammatory and regulated form of cell death), and epithelial-to-mesenchymal transition, the latter supporting the importance of tubular cell phenotype changes in the pathogenesis of DN. These findings could facilitate a better understanding of this complex disease and potentially open new avenues for the design of novel therapeutic approaches to DN.

The Dynamics and Plasticity of Epigenetics in Diabetic Kidney Disease: Therapeutic Applications Vis-à-Vis

Chronic kidney disease (CKD) refers to the phenomenon of progressive decline in the glomerular filtration rate accompanied by adverse consequences, including fluid retention, electrolyte imbalance, and an increased cardiovascular risk compared to those with normal renal function. The triggers for the irreversible renal function deterioration are multifactorial, and diabetes mellitus serves as a major contributor to the development of CKD, namely diabetic kidney disease (DKD). Recently, epigenetic dysregulation emerged as a pivotal player steering the progression of DKD, partly resulting from hyperglycemia-associated metabolic disturbances, rising oxidative stress, and/or uncontrolled inflammation. In this review, we describe the major epigenetic molecular mechanisms, followed by summarizing current understandings of the epigenetic alterations pertaining to DKD. We highlight the epigenetic regulatory processes involved in several crucial renal cell types: Mesangial cells, podocytes, tubular epithelia, and glomerular endothelial cells. Finally, we highlight epigenetic biomarkers and related therapeutic candidates that hold promising potential for the early detection of DKD and the amelioration of its progression.

Exosomal and Plasma Non-Coding RNA Signature Associated with Urinary Albumin Excretion in Hypertension

Non-coding RNA (ncRNA), released into circulation or packaged into exosomes, plays important roles in many biological processes in the kidney. The purpose of the present study is to identify a common ncRNA signature associated with early renal damage and its related molecular pathways. Three individual libraries (plasma and urinary exosomes, and total plasma) were prepared from each hypertensive patient (with or without albuminuria) for ncRNA sequencing analysis. Next, an RNA-based transcriptional regulatory network was constructed. The three RNA biotypes with the greatest number of differentially expressed transcripts were long-ncRNA (lncRNA), microRNA (miRNA) and piwi-interacting RNA (piRNAs). We identified a common 24 ncRNA molecular signature related to hypertension-associated urinary albumin excretion, of which lncRNAs were the most representative. In addition, the transcriptional regulatory network showed five lncRNAs (LINC02614, BAALC-AS1, FAM230B, LOC100505824 and LINC01484) and the miR-301a-3p to play a significant role in network organization and targeting critical pathways regulating filtration barrier integrity and tubule reabsorption. Our study found an ncRNA profile associated with albuminuria, independent of biofluid origin (urine or plasma, circulating or in exosomes) that identifies a handful of potential targets, which may be utilized to study mechanisms of albuminuria and cardiovascular damage.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

MicroRNAs: Potential biomarkers for reproduction, diagnosis, prognosis, and therapeutic in domestic animals

MicroRNA (miRNAs) are small non-coding RNA molecules involved in a wide range of biological processes through the post-transcriptional regulation of gene expression. Most studies evaluated microRNA expression in human, and despite fewer studies in veterinary medicine, this topic is one of the most exciting areas of modern veterinary medicine. miRNAs showed to be part of the pathogenesis of diseases and reproduction physiology in animals, making them biomarkers candidates. This review provides an overview of the current knowledge regarding miRNAs' role in reproduction and animal diseases, diagnostic and therapy.

Osteocrin ameliorates adriamycin nephropathy via p38 mitogen-activated protein kinase inhibition

Natriuretic peptides exert multiple effects by binding to natriuretic peptide receptors (NPRs). Osteocrin (OSTN) binds with high affinity to NPR-C, a clearance receptor for natriuretic peptides, and inhibits degradation of natriuretic peptides and consequently enhances guanylyl cyclase-A (GC-A/NPR1) signaling. However, the roles of OSTN in the kidney have not been well clarified. Adriamycin (ADR) nephropathy in wild-type mice showed albuminuria, glomerular basement membrane changes, increased podocyte injuries, infiltration of macrophages, and p38 mitogen-activated protein kinase (MAPK) activation. All these phenotypes were improved in OSTN- transgenic (Tg) mice and NPR3 knockout (KO) mice, with no further improvement in OSTN-Tg/NPR3 KO double mutant mice, indicating that OSTN works through NPR3. On the contrary, OSTN KO mice increased urinary albumin levels, and pharmacological blockade of p38 MAPK in OSTN KO mice ameliorated ADR nephropathy. In vitro, combination treatment with ANP and OSTN, or FR167653, p38 MAPK inhibitor, reduced Ccl2 and Des mRNA expression in murine podocytes (MPC5). OSTN increased intracellular cyclic guanosine monophosphate (cGMP) in MPC5 through GC-A. We have elucidated that circulating OSTN improves ADR nephropathy by enhancing GC-A signaling and consequently suppressing p38 MAPK activation. These results suggest that OSTN could be a promising therapeutic agent for podocyte injury.

Recent Advances in Diabetic Kidney Diseases: From Kidney Injury to Kidney Fibrosis

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease and end-stage renal disease. The natural history of DKD includes glomerular hyperfiltration, progressive albuminuria, declining estimated glomerular filtration rate, and, ultimately, kidney failure. It is known that DKD is associated with metabolic changes caused by hyperglycemia, resulting in glomerular hypertrophy, glomerulosclerosis, and tubulointerstitial inflammation and fibrosis. Hyperglycemia is also known to cause programmed epigenetic modification. However, the detailed mechanisms involved in the onset and progression of DKD remain elusive. In this review, we discuss recent advances regarding the pathogenic mechanisms involved in DKD.

Urinary podocyte markers in kidney diseases

Podocytes play an important role in the maintenance of kidney function, and they are the primary focus of many kidney diseases. Podocyte injury results in the shedding of podocyte-derived cellular fragments and podocyte-specific molecular targets into the urine, which may serve as biomarkers of kidney diseases. Intact podocytes, either viable or dead, and podocyte-derived microvesicles could be quantified in the urine by various centrifugation, visualization and culture methods. Podocyte-specific protein targets from the nucleus, cytoplasm, slit-diaphragm, glomerular capillary basement membrane, and cytoskeleton, as well as their corresponding messenger RNA (mRNA), in the urine could be quantified by western blotting, ELISA, or quantitative polymerase chain reaction. Although some of these techniques may be expensive or labor-intensive at present, they may become widely available in the future because of the improvement in technology and automation. The application of urinary podocyte markers for the diagnosis and monitoring of various kidney diseases have been explored but the published data in this area are not sufficiently systematic and lack external validation. Further research should focus on standardizing, comparing, and automizing laboratory methods, as well as defining their added value to the routine clinical tests.

MicroRNA-26 regulates the expression of CTGF after exposure to ionizing radiation

Radiation-induced fibrosis (RIF) is a serious complication that occurs after irradiation and which is caused by the deposition of extracellular matrix (ECM) proteins such as collagen. However, the underlying mechanisms, including the expression of the cytokines, that promote the RIF process, are not yet fully understood. MicroRNAs (miRNAs) have recently been suggested to act as post-transcriptional repressors for many genes; however, their role in the process of RIF remains to be elucidated. Our previous study showed that ionizing radiation increased the type I collagen expression through the activation of transforming growth factor (TGF)-β, while miR-29 repressed this increase. This study aimed to investigate the mechanisms by which the expression of connective tissue growth factor (CTGF), a downstream mediator of TGF-β, is controlled by miRNAs post-transcriptionally after exposure to ionizing radiation. The expression of CTGF in NIH-3T3 cells and mouse embryonic fibroblasts was increased by ionizing radiation. However, this increase was suppressed with a specific inhibitor of TGF-β receptor. Among the predictable miRNAs that target the CTGF gene, the expression of miR-26a was downregulated after exposure to ionizing radiation and this regulation was negatively mediated by TGF-β signaling. miR-26a negatively regulated the CTGF expression at the post-transcriptional level; however, ionizing radiation suppressed this negative regulation. In addition, the overexpression of miR-26a inhibited the expression of CTGF and type I collagen after irradiation. In conclusion, miR-26a modulates the expression of CTGF via TGF-β signaling in irradiated fibroblasts. The results suggest the potential application of miR-26a in the treatment of RIF.

PPARγ Mediates the Anti-Epithelial-Mesenchymal Transition Effects of FGF1ΔHBS in Chronic Kidney Diseases via Inhibition of TGF-β1/SMAD3 Signaling

Podocytes are essential components of the glomerular basement membrane. Epithelial-mesenchymal-transition (EMT) in podocytes results in proteinuria. Fibroblast growth factor 1 (FGF1) protects renal function against diabetic nephropathy (DN). In the present study, we showed that treatment with an FGF1 variant with decreased mitogenic potency (FGF1^ΔHBS) inhibited podocyte EMT, depletion, renal fibrosis, and preserved renal function in two nephropathy models. Mechanistic studies revealed that the inhibitory effects of FGF1^ΔHBS podocyte EMT were mediated by decreased expression of transforming growth factor β1 via upregulation of PPARγ. FGF1^ΔHBS enhanced the interaction between PPARγ and SMAD3 and suppressed SMAD3 nuclei translocation. We found that the anti-EMT activities of FGF1^ΔHBS were independent of glucose-lowering effects. These findings expand the potential uses of FGF1^ΔHBS in the treatment of diseases associated with EMT.

Transforming growth factor-β1-induced podocyte injury is associated with increased microRNA-155 expression, enhanced inflammatory responses and MAPK pathway activation

MicroRNA-155 (miR-155) is associated with various diseases. However, the potential role of miR-155 in early glomerular disease (EGD) remains elusive. In the present study, the clinical significance of urinary miR-155 expression was explored in patients with EGD using receiver operating characteristic curve analysis. Conditionally immortalized mouse podocytes were cultured in vitro and treated with transforming growth factor-β1 (TGF-β1) at different concentrations and durations. The gene expression levels of mRNAs and miR-155 were detected using reverse transcription-quantitative PCR. Synaptopodin, CD2-associated protein (CD2AP), p38, and extracellular signal-regulated kinase (Erk) 1/2 expressions were detected using western blotting. Cell supernatants were collected for assaying tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations using enzyme-linked immunosorbent assay. The Pearson correlation analysis was used to analyze the correlation between miR-155 levels and TNF-α or IL-6. It was found that miR-155 levels in urine have high sensitivity and specificity in the diagnosis of EGD. Time- and dose-dependent TGF-β1 treatments downregulated synaptopodin and CD2AP expression levels, and activated the p38 and Erk 1/2 pathway. However, these effects were attenuated by p38 and Erk 1/2 phosphorylation inhibitors. Additionally, TNF-α and IL-6 secretions were elevated, and their concentrations were positively correlated with the expression of miR-155 during podocyte injury. Thus, the present study indicated that miR-155 is a potential biomarker for the diagnosis of EGD, and its expression is associated with the release of pro-inflammatory cytokines and activation of mitogen-activated protein kinase (MAPK) pathway in TGF-β1-induced podocyte injury. The present study suggests that the TGF-β1/miR-155/MAPK axis is a novel target in the mechanism of EGD.

Non-Coding RNAs as Biomarkers and Therapeutic Targets for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the most common diabetic complication and is a leading cause of end-stage kidney disease. Increasing evidence shows that DKD is regulated not only by many classical signaling pathways but also by epigenetic mechanisms involving chromatin histone modifications, DNA methylation, and non-coding RNA (ncRNAs). In this review, we focus on our current understanding of the role and mechanisms of ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the pathogenesis of DKD. Of them, the regulatory role of TGF-β/Smad3-dependent miRNAs and lncRNAs in DKD is highlighted. Importantly, miRNAs and lncRNAs as biomarkers and therapeutic targets for DKD are also described, and the perspective of ncRNAs as a novel therapeutic approach for combating diabetic nephropathy is also discussed.

Urinary- and Plasma-Derived Exosomes Reveal a Distinct MicroRNA Signature Associated With Albuminuria in Hypertension

Urinary albumin excretion (UAE) is a marker of cardiovascular risk and renal damage in hypertension. MicroRNAs (miRNAs) packaged into exosomes function as paracrine effectors in cell communication and the kidney is not exempt. This study aimed to state an exosomal miRNA profile/signature associated to hypertension with increased UAE and the impact of profibrotic TGF-β1 (transforming growth factor β1) on exosomes miRNA release. Therefore, exosomes samples from patients with hypertension with/without UAE were isolated and characterized. Three individual and unique small RNA libraries from each subject were prepared (total plasma, urinary, and plasma-derived exosomes) for next-generation sequencing profiling. Differentially expressed miRNAs were over-represented in Kyoto Encyclopedia of Genes and Genomes pathways, and selected miRNAs were validated by real-time quantitative polymerase chain reaction in a confirmation cohort. Thus, a signature of 29 dysregulated circulating miRNAs was identified in UAE hypertensive subjects, regulating 21 pathways. Moreover, changes in the levels of 4 exosomes-miRNAs were validated in a confirmation cohort and found associated with albuminuria. In particular miR-26a, major regulator of TGF-β signaling, was found downregulated in both type of exosomes when compared with healthy controls and to hypertension normoalbuminurics (P<0.01). Similarly, decreased miR-26a levels were found in podocyte-derived exosomes after TGF-β stress. Our results revealed an exosomes miRNA signature associated to albuminuria in hypertension. In particular, exosomes miR-26a seemed to play a key role in the regulation of TGF-β, a relevant effector in podocyte damage. These findings support the use of exosomes miRNAs as biomarkers of cardiovascular risk progression and therapeutic tools in early kidney damage.

Non-coding RNAs modulate function of extracellular matrix proteins

The extracellular matrix (ECM) creates a multifaceted system for the interaction of diverse structural proteins, matricellular molecules, proteoglycans, hyaluronan, and various glycoproteins that collaborate and bind with each other to produce a bioactive polymer. Alterations in the composition and configuration of ECM elements influence the cellular phenotype, thus participating in the pathogenesis of several human disorders. Recent studies indicate the crucial roles of non-coding RNAs in the modulation of ECM. Several miRNAs such as miR-21, miR-26, miR-19, miR-140, miR-29, miR-30, miR-133 have been dysregulated in disorders that are associated with disruption or breakdown of the ECM. Moreover, expression of MALAT1, PVT1, SRA1, n379519, RMRP, PFL, TUG1, TM1P3, FAS-AS1, PART1, XIST, and expression of other lncRNAs is altered in disorders associated with the modification of ECM components. In the current review, we discuss the role of lncRNAs and miRNAs in the modification of ECM and their relevance with the pathophysiology of human disorders such as cardiac/ lung fibrosis, cardiomyopathy, heart failure, asthma, osteoarthritis, and cancers.

MiR-325-3p inhibits renal inflammation and fibrosis by targeting CCL19 in diabetic nephropathy

Diabetic nephropathy (DN), a common cardiovascular disease, has been a global health threat. MicroRNAs (miRNAs) have been proposed to frequently participate in the occurrence and development of DN, however, the role of miR-325-3p in DN remains uncharacterized. Our research aimed to explore the function and mechanism of miR-325-3p in DN. Bioinformatics analysis (Targetscan, http://www.targetscan.org) and a wide range of experiments including RT-qPCR, CCK-8 assay, western blot, luciferase reporter assay, RNA immunoprecipitation (RIP) assays, urine protein and blood glucose assays, histology analysis and morphometric analysis were used to explore the function and mechanism of miR-325-3p and C-C motif chemokine ligand 19 (CCL19). CCL19 could facilitate the progression of DN by inhibiting cell viability and promoting inflammation and fibrosis in HK-2 and HMC cells. In addition, CCL19 was confirmed to be targeted and negatively regulated by miR-325-3p. Rescue assays validated that the impacts of miR-325-3p mimics on the viability, inflammation and fibrosis of HK-2 and HMC cells were recovered by CCL19 overexpression. To sum up, miR-325-3p inhibits renal inflammation and fibrosis by targeting CCL19 in a DN cell model and mice model, implying miR-325-3p as a possible therapeutic target for DN treatment.

LncRNA KCNQ1OT1 knockdown inhibits viability, migration and epithelial-mesenchymal transition in human lens epithelial cells via miR-26a-5p/ITGAV/TGF-beta/Smad3 axis

BACKGROUND

Long noncoding RNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) takes part in diabetic cataract progression. This research aims to analyze the function and mechanism of KCNQ1OT1 on viability, migration and epithelial-mesenchymal transition (EMT) in lens epithelial cells.

METHODS

20 diabetic cataract posterior lens capsule tissues and normal samples were collected. Lens epithelial cells (SRA01/04) were stimulated via high glucose (HG). The levels of KCNQ1OT1, miR-26a-5p, integrin αV (ITGAV), TGF-β, Smad3 and phosphorylated (p)-Smad3 were measured via quantitative real-time polymerase chain reaction or Western blot. Cell viability, migration and EMT were analyzed via MTT, wound healing, transwell and Western blot assays. The target relationship between miR-26a-5p and KCNQ1OT1 or ITGAV was determined via luciferase reporter assay.

RESULTS

KCNQ1OT1 was up-regulated and miR-26a-5p level was reduced in diabetic cataract tissues and HG-treated SRA01/04 cells. Silence of KCNQ1OT1 or miR-26a-5p up-regulation repressed cell viability, migration and EMT in SRA01/04 cells stimulated via HG. KCNQ1OT1 could target miR-26a-5p and controlled cell viability, migration and EMT via regulating miR-26a-5p. ITGAV was targeted via miR-26a-5p and positively regulated via KCNQ1OT1. ITGAV overexpression promoted cell viability, migration and EMT in HG-treated SRA01/04 cells, which were mitigated by KCNQ1OT1 silence. KCNQ1OT1 knockdown mitigated HG-induced the activation of TGF-β/Smad3 signaling by regulating miR-26a-5p.

CONCLUSION

KCNQ1OT1 knockdown represses cell viability, migration and EMT through miR-26a-5p/ITGAV/TGF-β/Smad3 axis in SRA01/04 cells under HG condition, providing a new target for the treatment of diabetic cataract.

MicroRNAs in Chronic Kidney Disease: Four Candidates for Clinical Application

There are still major challenges regarding the early diagnosis and treatment of chronic kidney disease (CKD), which is in part due to the fact that its pathophysiology is very complex and not clarified in detail. The diagnosis of CKD commonly is made after kidney damage has occurred. This highlights the need for better mechanistic insight into CKD as well as improved clinical tools for both diagnosis and treatment. In the last decade, many studies have focused on microRNAs (miRs) as novel diagnostic tools or clinical targets. MiRs are small non-coding RNA molecules that are involved in post-transcriptional gene regulation and many have been studied in CKD. A wide array of pre-clinical and clinical studies have highlighted the potential role for miRs in the pathogenesis of hypertensive nephropathy, diabetic nephropathy, glomerulonephritis, kidney tubulointerstitial fibrosis, and some of the associated cardiovascular complications. In this review, we will provide an overview of the miRs studied in CKD, especially highlighting miR-103a-3p, miR-192-5p, the miR-29 family and miR-21-5p as these have the greatest potential to result in novel therapeutic and diagnostic strategies.

Adipose mesenchymal stem cell-derived extracellular vesicles containing microRNA-26a-5p target TLR4 and protect against diabetic nephropathy

Diabetic nephropathy (DN) is a complication of diabetes that is increasing in prevalence in China. Extracellular vesicles (EVs) carrying microRNAs (miRs) may represent a useful tool in the development of therapies for DN. Here, we report that EVs released by adipose-derived mesenchymal stem cells (ADSCs) during DN contain a microRNA, miR-26a-5p, that suppresses DN. Using bioinformatic analyses, we identified differentially expressed miRs in EVs from ADSCs and in DN and predicted downstream regulatory target genes. We isolated mesenchymal stem cells (MSCs) from adipose tissues and collected EVs from the ADSCs. We exposed mouse glomerular podocytes and MP5 cells to high glucose (HG), ADSC-derived EVs, miR-26a-5p inhibitor/antagomir, Toll-like receptor 4 (TLR4) plasmids, or the NF-κB pathway activator (phorbol-12-myristate-13-acetate, or PMA). We used the cell counting kit-8 (CCK-8) assay and flow cytometry to investigate the impact of miR-26a-5p on cell viability and apoptosis and validated the results of these assays with in vivo experiments in nude mice. We found that in DN, miR-26a-5p is expressed at very low levels, whereas TLR4 is highly expressed. Of note, EVs from ADSCs ameliorated the pathological symptoms of DN in diabetic mice and transferred miR-26a-5p to HG-induced MP5 cells, improving viability while suppressing the apoptosis of MP5 cells. We also found that miR-26a-5p protects HG-induced MP5 cells from injury by targeting TLR4, inactivating the NF-κB pathway, and downregulating vascular endothelial growth factor A (VEGFA). Moreover, ADSC-derived EVs transferred miR-26a-5p to mouse glomerular podocytes, which ameliorated DN pathology. These findings suggest that miR-26a-5p from ADSC-derived EVs protects against DN.

Using prediction models to identify miRNA-based markers of low dose rate chronic stress

Robust biomarkers of exposure to chronic low dose stressors such as ionizing radiation, particularly following chronic low doses and dose-rates, are urgently needed. MicroRNAs (miRNA) have emerged as promising markers of exposure to high dose and dose-rate. Here, we evaluated the feasibility of classifying γ-radiation exposure at different dose rates based on miRNA expression levels. Our objective was to identify miRNA-signatures discriminating between exposure to γ-radiation or not, including exposure to chronic low dose rates. We exposed male CBA/CaOlaHsd and C57BL/6NHsd wild-type mice to 0, 2.5, 10 and 100 mGy/h γ-irradiation (3 Gy total-dose). From an initial screening of 576 miRNAs, a set of 21 signature-miRNAs was identified based on differential expression (>± 2-fold or p < 0.05). This 21-signature miRNA panel was investigated in 39 samples from 4/5 livers/group/mouse strain. A set of significantly differentially expressed miRNAs was identified in all γ-irradiated samples. Most miRNAs were upregulated in all γ-irradiated groups compared to control, and functional analysis of these miRNAs revealed involvement in several cancer-related signaling pathways. To identify miRNAs that distinguished exposed mice from controls, nine prediction methods; i.e., six variants of generalized regression models, random-forest, boosted-tree and nearest-shrunken-centroid (PAM) were used. The generalized regression methods seem to outperform the other prediction methods for classification of irradiated and control samples. Using the 21-miRNA panel in the prediction models, we identified sets of candidate miRNA-markers that predict exposure to γ-radiation. Among the top10 miRNA predictors, contributing most in each of the three γ-irradiated groups, three miRNA predictors (miR-140-3p, miR-133a-5p and miR-145a-5p) were common. Three miRNAs, miR-188-3p/26a-5p/26b-5p, were specific for lower dose-rate γ-radiation. Similarly, exposure to the high dose-rates was also correctly predicted, including mice exposed to X-rays. Our approach identifying miRNA-based signature panels may be extended to classify exposure to environmental, nutritional and life-style-related stressors, including chronic low-stress scenarios.

Interactions Among Non-Coding RNAs in Diabetic Nephropathy

Diabetic Nephropathy (DN) is the most common cause of End-stage renal disease (ESRD). Although various treatments and diagnosis applications are available, DN remains a clinical and economic burden. Recent findings showed that noncoding RNAs (ncRNAs) play an important role in DN progression, potentially can be used as biomarkers and therapeutic targets. NcRNAs refers to the RNA species that do not encode for any protein, and the most known ncRNAs are the microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). Dysregulation of these ncRNAs was reported before in DN patients and animal models of DN. Importantly, there are some interactions between these ncRNAs to regulate the crucial steps in DN progression. Here, we aimed to discuss the reported ncRNAs in DN and their interactions with critical genes in DN progression. Elucidating these ncRNAs regulatory network will allow for a better understanding of the molecular mechanisms in DN and how they can act as new biomarkers for DN and also as the potential targets for treatment.

Targeting the progression of chronic kidney disease

Chronic kidney disease (CKD) is a devastating condition that is reaching epidemic levels owing to the increasing prevalence of diabetes mellitus, hypertension and obesity, as well as ageing of the population. Regardless of the underlying aetiology, CKD is slowly progressive and leads to irreversible nephron loss, end-stage renal disease and/or premature death. Factors that contribute to CKD progression include parenchymal cell loss, chronic inflammation, fibrosis and reduced regenerative capacity of the kidney. Current therapies have limited effectiveness and only delay disease progression, underscoring the need to develop novel therapeutic approaches to either stop or reverse progression. Preclinical studies have identified several approaches that reduce fibrosis in experimental models, including targeting cytokines, transcription factors, developmental and signalling pathways and epigenetic modulators, particularly microRNAs. Some of these nephroprotective strategies are now being tested in clinical trials. Lessons learned from the failure of clinical studies of transforming growth factor β1 (TGFβ1) blockade underscore the need for alternative approaches to CKD therapy, as strategies that target a single pathogenic process may result in unexpected negative effects on simultaneously occurring processes. Additional promising avenues include preventing tubular cell injury and anti-fibrotic therapies that target activated myofibroblasts, the main collagen-producing cells.

Noncoding RNAs in Diabetic Nephropathy: Pathogenesis, Biomarkers, and Therapy

The correlation between diabetes and systematic well-being on human life has long established. As a common complication of diabetes, the prevalence of diabetic nephropathy (DN) has been increasing globally. DN is known to be a major cause of end-stage kidney disease (ESKD). Till now, the molecular mechanisms for DN have not been fully explored and the effective therapies are still lacking. Noncoding RNAs are a class of RNAs produced by genome transcription that cannot be translated into proteins. It has been documented that ncRNAs participate in the pathogenesis of DN by regulating inflammation, apoptosis, autophagy, cell proliferation, and other pathological processes. In this review, the pathological roles and diagnostic and therapeutic potential of three types of ncRNAs (microRNA, long noncoding RNA, and circular RNA) in the progression of DN are summarized and illustrated.

20(S)-Ginsenoside Rg3 Protects Kidney from Diabetic Kidney Disease via Renal Inflammation Depression in Diabetic Rats

20(S)-Ginsenoside Rg3 (20(S)-Rg3) has been shown to induce apoptosis by interfering with several signaling pathways. Furthermore, it has been reported to have anticancer and antidiabetic effects. In order to detect the protective effect of 20(S)-Rg3 on diabetic kidney disease (DKD), diabetic rat models which were established by administering high-sugar, high-fat diet combined with intraperitoneal injection of streptozotocin (STZ), and age-matched wild-type (WT) rat were given 20(S)-Rg3 for 12 weeks, with three groups: control group (normal adult rats with saline), diabetic group (diabetic rats with saline), and 20(S)-Rg3 treatment group (diabetic rats with 20(S)-Rg3 (10 mg/kg body weight/day)). The biochemical indicators and the changes in glomerular basement membrane and mesangial matrix were detected. TUNEL staining was used to detect glomerular and renal tubular cell apoptosis. Immunohistochemical staining was used to detect the expression of fibrosis factors and inflammation factors in rat kidney tissues. Through periodic acid-Schiff staining, we observed that the change in renal histology was improved and renal tubular epithelial cell apoptosis decreased significantly by treatment with 20(S)-Rg3. Plus, the urine protein decreased in the rats with the 20(S)-Rg3 treatment. Fasting blood glucose, creatinine, total cholesterol, and triglyceride levels in the 20(S)-Rg3 treatment group were all lower than those in the diabetic group. Mechanistically, 20(S)-Rg3 dramatically downregulated the expression of TGF-β1, NF-κB65, and TNF-α in the kidney. These resulted in a significant prevention of renal damage from the inflammation. The results of the current study suggest that 20(S)-Rg3 could potentially be used as a novel treatment against DKD.

Exogenous miR-26a suppresses muscle wasting and renal fibrosis in obstructive kidney disease

Kidney fibrosis occurs in almost every type of chronic kidney disease. We found that microRNA (miR)-26a was decreased in the kidney, muscle, and exosomes of unilateral ureteral obstruction (UUO) mice. We hypothesized that exogenous miR-26 could suppresses renal fibrosis and muscle wasting in obstructive kidney disease. For this purpose, we generated exosomes that encapsulated miR-26, then injected these into skeletal muscle of UUO mice. The expression of miR-26a was elevated in serum exosomes from UUO mice following exosome-miR-26a injection. In these mice, muscle wasting has been ameliorated as evidenced by increased muscle weights. In addition, a muscle atrophy marker, myostatin, is increased in UUO muscle; provision of miR-26a abolished this increase. We detected a remote effect of exosomes containing miR-26a in UUO-induced renal fibrosis. The intervention of miR-26a attenuated UUO-induced renal fibrosis as determined by immunohistological assessment of α-smooth muscle actin and Masson's trichrome staining. Furthermore, exogenous miR-26a decreased the protein levels of 2 profibrosis proteins, connective tissue growth factor (CTGF) and TGF-β1, in UUO kidney. Our data showed that exosomes containing miR-26a prevented muscle atrophy by inhibiting the transcription factor forkhead box O1. Likewise, the exosome-carried miR-26a limited renal fibrosis by directly suppressing CTGF. Our findings provide an experimental basis for exosome-mediated therapy of muscle atrophy and renal fibrosis.-Zhang, A., Wang, H., Wang, B., Yuan, Y., Klein, J. D., Wang, X. H. Exogenous miR-26a suppresses muscle wasting and renal fibrosis in obstructive kidney disease.

Deletion of connective tissue growth factor ameliorates peritoneal fibrosis by inhibiting angiogenesis and inflammation

Background

Connective tissue growth factor (CTGF/CCN2) regulates the signalling of other growth factors and promotes fibrosis. CTGF is increased in mice and humans with peritoneal fibrosis. Inhibition of CTGF has not been examined as a potential therapeutic target for peritoneal fibrosis because systemic CTGF knockout mice die at the perinatal stage.

Methods

To study the role of CTGF in peritoneal fibrosis of adult mice, we generated CTGF conditional knockout (cKO) mice by crossing CTGF floxed mice with RosaCreERT2 mice. We administered tamoxifen to Rosa-CTGF cKO mice to delete the CTGF gene throughout the body. We induced peritoneal fibrosis by intraperitoneal injection of chlorhexidine gluconate (CG) in wild-type and Rosa-CTGF cKO mice.

Results

Induction of peritoneal fibrosis in wild-type mice increased CTGF expression and produced severe thickening of the peritoneum. In contrast, CG-treated Rosa-CTGF cKO mice exhibited reduced thickening of the peritoneum. Peritoneal equilibration test revealed that the excessive peritoneal small-solute transport in CG-treated wild-type mice was normalized by CTGF deletion. CG-treated Rosa-CTGF cKO mice exhibited a reduced number of αSMA-, Ki67-, CD31- and MAC-2-positive cells in the peritoneum. Analyses of peritoneal mRNA showed that CG-treated Rosa-CTGF cKO mice exhibited reduced expression of Cd68, Acta2 (αSMA), Pecam1 (CD31) and Vegfa.

Conclusions

These results indicate that a deficiency of CTGF can reduce peritoneal thickening and help to maintain peritoneal function by reducing angiogenesis and inflammation in peritoneal fibrosis. These results suggest that CTGF plays an important role in the progression of peritoneal fibrosis.

MicroRNA-26a: An Emerging Regulator of Renal Biology and Disease

MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that modulate many key biological processes by simultaneously suppressing multiple target genes. Among them, miR-26a, a conserved miRNA among vertebrates, is highly expressed in various tissues. Accumulating evidence demonstrates that miR-26a plays pivotal roles in cellular differentiation, cell growth, apoptosis, and metastasis, thereby participating in the initiation and development of various human diseases, such as metabolic disease and cancer. More recently, miR-26a was found as a versatile regulator of renal biology and disease. miR-26a is intensively involved in the maintenance of podocyte homeostasis and the actin cytoskeleton. It is also able to modulate the homeostasis and function of mesangial cells. In addition, miR-26a affects the expansion of regulatory T cells in the context of ischemia-reperfusion injury and autoimmune diabetes and thus protects the renal system from immune attack. These available data strongly suggest that renal miR-26a possesses critical pathological functions and represents a potential target for renal disease therapies. This review summarizes current knowledge of miR-26a in renal biology and disease, laying the foundation for exploring its previously unknown functions and mechanisms in the renal system.

Salvia miltiorrhiza in diabetes: A review of its pharmacology, phytochemistry, and safety

BACKGROUND

Salvia miltiorrhiza (SM), one of the frequently used herbs in traditional Chinese medicine (TCM), has now attracted rising interests for a possible alternative in the management of diabetes. This review is aimed to providing a comprehensive perspective of SM in phytochemical constituents, pharmacological activities against diabetes and its complications, and safety.

METHODS

A comprehensive search of published literatures was conducted to locate original publications pertaining to SM and diabetes till the end of 2017 using PubMed, China National Knowledge Infrastructure, National Science and Technology Library, China Science and Technology Journal Database, and Web of Science database. The main inquiry was used for the presence of the following keywords in various combinations in the titles and abstracts: Salvia miltiorrhiza, diabetes, obesity, phytochemistry, pharmacology, and safety. About 200 research papers and reviews were consulted.

RESULTS

SM exhibited anti-diabetic activities by treating macro- and micro-vascular diseases in preclinical experiments and clinical trials through an improvement of redox homeostasis and inhibition of apoptosis and inflammation via the regulation of Wnt/β-catenin, TSP-1/TGF-β1/STAT3, JNK/PI3K/Akt, kinin B2 receptor-Akt-GSK-3β, AMPKβ/PGC-1α/Sirt3, Akt/AMPK, TXNIP/NLRP3, TGF-β1/NF-κB, mineralocorticoid receptor/Na⁺/K⁺-ATPase, AGEs/RAGE, Nrf2/Keap1, CaMKKβ/AMPK, AMPK/ACC, IRS-1/PI3K signaling pathways, and modulation of K⁺-Ca²⁺ channels, as well as influence of VEGF, NOS, AGEs, PPAR expression and hIAPP aggregation. The antidiabetic effects of this herb may be related to its TCM characters of improving blood circulation and reliving blood stasis. The main ingredients of SM included salvianolic acids and diterpenoid tanshinones, which have been well studied in the diabetic animals. Acute and subacute toxicity studies supported the notion that SM is well tolerated.

CONCLUSION

SM may offer a new strategy for prevention and treatment of diabetes and its complications that stimulates extensive research into identifying potential anti-diabetic compounds and fractions as well as exploring the underlying mechanisms of this herb. Further scientific evidences are still required from well-designed preclinical experiments and clinical trials on its anti-diabetic effects and safety.

miR-26a Limits Muscle Wasting and Cardiac Fibrosis through Exosome-Mediated microRNA Transfer in Chronic Kidney Disease

Uremic cardiomyopathy and muscle atrophy are associated with insulin resistance and contribute to chronic kidney disease (CKD)-induced morbidity and mortality. We hypothesized that restoration of miR-26a levels would enhance exosome-mediated microRNA transfer to improve muscle wasting and cardiomyopathy that occur in CKD.

Methods: Using next generation sequencing and qPCR, we found that CKD mice had a decreased level of miR-26a in heart and skeletal muscle. We engineered an exosome vector that contained Lamp2b, an exosomal membrane protein gene fused with a muscle-specific surface peptide that targets muscle delivery. We transfected this vector into muscle satellite cells and then transduced these cells with adenovirus that expresses miR-26a to produce exosomes encapsulated miR-26a (Exo/miR-26a). Exo/miR-26a was injected once per week for 8 weeks into the tibialis anterior (TA) muscle of 5/6 nephrectomized CKD mice.

Results: Treatment with Exo/miR-26a resulted in increased expression of miR-26a in skeletal muscle and heart. Overexpression of miR-26a increased the skeletal muscle cross-sectional area, decreased the upregulation of FBXO32/atrogin-1 and TRIM63/MuRF1 and depressed cardiac fibrosis lesions. In the hearts of CKD mice, FoxO1 was activated, and connective tissue growth factor, fibronectin and collagen type I alpha 1 were increased. These responses were blunted by injection of Exo/miR-26a. Echocardiograms showed that cardiac function was improved in CKD mice treated with Exo/miR-26a.

Conclusion: Overexpression of miR-26a in muscle prevented CKD-induced muscle wasting and attenuated cardiomyopathy via exosome-mediated miR-26a transfer. These results suggest possible therapeutic strategies for using exosome delivery of miR-26a to treat complications of CKD.

MicroRNAs in the Progress of Diabetic Nephropathy: A Systematic Review and Meta-Analysis

Background

We conducted a systematic review and meta-analysis of existing literature to evaluate the different outcomes of microRNAs (miRNAs) in diabetic nephropathy (DN), including urinary albumin excretion rates, urinary albumin creatinine rates, glomerular filtration rate, HbAc1, and creatinine.

Methods

Electronic databases including PUBMED, MEDLINE, and EMBASE were searched for eligible publications to July 2018. The following comparisons between treatment groups were included: normal group versus DN group; control group versus micro/macroalbuminuria group.

Results

Twelve eligible studies that included 2500 participants were finally recruited in this meta-analysis. Fifteen miRNAs (miRNA-21, miRNA-181b, miRNA-194, miRNA-30, miRNA-215, and others) were upregulated whereas seven miRNAs (miRNA-26a, miRNA-126, miRNA-424, miRNA-574-3p, miR-223, miR-155, and miR-192) were downregulated in the DN group compared with control groups. The miR-133b, miR-342, miR-30, miR-192, miR-194, and miR-215 were significantly correlated in urinary albumin excretion rates (r=0.33, 95% CI= 0.26-0.39). miR-192, miR-217, miR-15b, miR-34a, and miR-636 were correlated with urinary albumin creatinine rates (r=0.69; 95% CI=0.12-0.92), while miR-133b, miR-345, miR-33, miR-326, miR-574-3p, miR-126, miR-217, miR-15b, miR-34a, and miR-636 were significantly correlated with HbAc1 (r =0.23, 95% CI = 0.15-0.31). There were twelve miRNAs that were closely related to the glomerular filtration rate (r=0.28, 95% CI =0.21-0.34). Creatinine (r=0.33, 95% CI = 0.22-0.40) was significantly different between normal and DN groups.

Conclusions

The meta-analysis acquired the correlations between miRNAs and outcomes including UAER, UACR, eGFR, HbAc1, and creatinine in DN. It suggested that miRNAs may participate in the pathogenesis of DN process.

Ergosterol Ameliorates Diabetic Nephropathy by Attenuating Mesangial Cell Proliferation and Extracellular Matrix Deposition via the TGF-β1/Smad2 Signaling Pathway

(1) Background: Diabetic nephropathy, a microvascular complication of diabetes, is one of the principal causes of end-stage renal disease worldwide. The aim of this study was to explore the therapeutic effects of ergosterol on diabetic nephropathy. (2) Methods: Streptozotocin (STZ)-induced C57BL/6 diabetic mice were treated with ergosterol (10, 20, 40 mg/kg/day) for 8 weeks by oral gavage. The in vitro study employed rat mesangial cells exposed to 30 mM glucose for 48 h in the presence of 10 or 20 μM ergosterol. (3) Results: Ergosterol treatment improved body weights, ameliorated the majority of biochemical and renal functional parameters and histopathological changes, and reduced extracellular matrix (ECM) deposition in diabetic mice. In vitro, ergosterol suppressed proliferation, reduced the levels of ECM proteins, and increased the expression of matrix metalloproteinase-2 and -9 in high glucose-induced mesangial cells; Furthermore, ergosterol markedly improved transforming growth factor-β1 (TGF-β1) expression, enhanced phosphorylation levels of drosophila mothers against decapentaplegic 2 (Smad2), and regulated the downstream factors in vivo and in vitro. (4) Conclusions: Ergosterol alleviated mesangial cell proliferation and the subsequent ECM deposition by regulating the TGF-β1/Smad2 signaling pathway.

LncRNA NEAT1 promotes extracellular matrix accumulation and epithelial-to-mesenchymal transition by targeting miR-27b-3p and ZEB1 in diabetic nephropathy

Diabetic nephropathy (DN) is a kind of microvascular complications of diabetes. Long noncoding RNAs (lnRNAs) can participate in the development of various diseases, including DN. However, the function of lncRNA NEAT1 is unclear. In our present study, we reported that NEAT1 was significantly increased in streptozotocin-induced DN rat models and high-glucose-induced mice mesangial cells. We observed that knockdown of NEAT1 greatly inhibited renal injury of DN rats. Meanwhile, downregulation of NEAT1-modulated extracellular matrix (ECM) proteins (ASK1, fibronectin, and TGF-β1) expression and epithelial-mesenchymal transition (EMT) proteins (E-cadherin and N-cadherin) in vitro. Previously, miR-27b-3p has been reported to be involved in diabetes. Here, miR-27b-3p was decreased in DN rats and high-glucose-induced mice mesangial cells. The direct correlation between NEAT1 and miR-27b-3p was validated using the dual-luciferase reporter assay and RNA immunoprecipitation experiments. In addition, zinc finger E-box binding homeobox 1 (ZEB1), which has been identified in the process of EMT clearly contributes to EMT progression. ZEB1 was predicted as a target of miR-27b-3p and overexpression of miR-27b-3p dramatically repressed ZEB1 expression. Therefore, our data implied the potential role of NEAT1 in the fibrogenesis and EMT in DN via targeting miR-27b-3p and ZEB1.

The Use of Targeted Next Generation Sequencing to Explore Candidate Regulators of TGF-β1's Impact on Kidney Cells

Aims/Hypothesis: Transforming growth factor-beta (TGF-β1) plays an important regulatory role in the progression of chronic kidney failure. Further, damage to kidney glomerular mesangial cells is central to the progression of diabetic nephropathy. The aim of this study was to explore the genetic associations between mRNA, microRNA, and epigenetics in mesangial cells in response to TGF-β1.

Methods: The regulatory effects of TGF-β1 on mesangial cells were investigated at different molecular levels by treating mesangial cells with TGF-β1 for 3 days followed by genome-wide miRNA, RNA, DNA methylation, and H3K27me3 expression profiling using next generation sequencing (NGS).

Results: Our results provide the first comprehensive, computationally integrated report of RNA-Seq, miRNA-Seq, and epigenomic analyses across all genetic variations, confirming the occurrence of DNA methylation and H3K27me3 in response to TGF-β1. Our findings show that the expression of KLF7 and Gja4 are involved in TGF-β1 regulated DNA methylation. Our data also provide evidence of the association between epigenetic changes and the expression of genes closely related to TGF-β1 regulation.

Conclusion: This study has advanced our current knowledge of mechanisms that contribute to the expression of TGF-β1-regulated genes involved in the pathogenesis of kidney disease. The molecular underpinnings of TGF-β1 stimulation of kidney cells was determined, thereby providing a robust platform for further target exploration.

Urinary Exosome-Derived microRNAs Reflecting the Changes in Renal Function in Cats

Increased incidence of kidney disease (KD) is a common concern in human and companion animals. Cats, in particular, are highly susceptible to KD. Novel KD biomarkers would help to address these problems. Therefore, we are focusing on microRNA, a highly conserved nucleic acid, as a KD biomarker for various animals. We previously reported that altered levels of urinary exosome (UExo)-derived microRNAs indicate renal pathologies in dogs. This study comprehensively examined UExo-derived microRNAs, which reflected the KD status in cats. The examined cats were divided into two groups: normal renal function (NR) and KD. Based on our previous data in dogs and cats, as well as the present data on UExo-derived microRNAs in cats by next-generation sequencing, let-7b, let-7f, miR-10a, miR-10b, miR-21a, miR-22, miR-26a, miR-27b, miR-146a, miR-181a, miR-191, and miR-486a were identified as biomarker candidates. In summary, the levels of UExo-derived let-7b, miR-22, and miR-26a significantly decreased in cats with KD from the early stages of the disease. UExo-derived miRNA levels normalized to urinary creatinine or total RNA of miR-21a was significantly higher in the KD group. Importantly, the ratio of UExo-derived miR-21a to let-7b showed a significant and strongest correlation with serum creatinine (ρ = 0.751), blood urea nitrogen (ρ = 0.754), and urinary creatinine (ρ = −0.421) among all examined indices. Further, the ratio of miR-181a to let-7b or miR-10b significantly correlated with the progression of renal dysfunction in the KD group. Thus, we identified that UExo-derived microRNAs in cats, and their raw and normalized levels could indicate altered renal function.

Noncoding RNAs as therapeutic targets in early stage diabetic kidney disease

Diabetic kidney disease (DKD) is a major renal complication of diabetes that leads to renal dysfunction and end-stage renal disease (ESRD). Major features of DKD include accumulation of extracellular matrix proteins and glomerular hypertrophy, especially in early stage. Transforming growth factor-β plays key roles in regulation of profibrotic genes and signal transducers such as Akt kinase and MAPK as well as endoplasmic reticulum stress, oxidant stress, and autophagy related to hypertrophy in diabetes. Many drugs targeting the pathogenic signaling in DKD (mostly through protein-coding genes) are under development. However, because of the limited number of protein-coding genes, noncoding RNAs (ncRNAs) including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are attracting more attention as potential new drug targets for human diseases. Some miRNAs and lncRNAs regulate each other (by hosting, enhancing transcription from the neighbor, hybridizing each other, and changing chromatin modifications) and create circuits and cascades enhancing the pathogenic signaling in DKD. In this short and focused review, the functional significance of ncRNAs (miRNAs and lncRNAs) in the early stages of DKD and their therapeutic potential are discussed.