Absence of miR-146a in Podocytes Increases Risk of Diabetic Glomerulopathy via Up-regulation of ErbB4 and Notch-1

ERBB4 selectively amplifies TGF-β pro-metastatic responses

Transforming growth factor β (TGF-β) is well known to play paradoxical roles in tumorigenesis as it has both growth-inhibitory and pro-metastatic effects. However, the underlying mechanisms of how TGF-β drives the opposing responses remain largely unknown. Here, we report that ERBB4, a member of the ERBB receptor tyrosine kinase family, specifically promotes TGF-β's metastatic response but not its anti-growth response. ERBB4 directly phosphorylates Tyr162 in the linker region of SMAD4, which enables SMAD4 to achieve a higher DNA-binding ability and potentiates TGF-β-induced gene transcription associated with epithelial-to-mesenchymal transition (EMT), cell migration, and invasion without affecting the genes involved in growth inhibition. These selective effects facilitate lung cancer metastasis in mouse models. This discovery sheds light on the previously unrecognized role of SMAD4 as a substrate of ERBB4 and highlights the selective involvement of the ERBB4-SMAD4 regulatory axis in tumor metastasis.

Podocyte senescence: from molecular mechanisms to therapeutics

As an important component of the glomerular filtration membrane, the state of the podocytes is closely related to kidney function, they are also key cells involved in aging and play a central role in the damage caused by renal aging. Therefore, understanding the aging process of podocytes will allow us to understand their susceptibility to injury and identify targeted protective mechanisms. In fact, the process of physiological aging itself can induce podocyte senescence. Pathological stresses, such as oxidative stress, mitochondrial damage, secretion of senescence-associated secretory phenotype, reduced autophagy, oncogene activation, altered transcription factors, DNA damage response, and other factors, play a crucial role in inducing premature senescence and accelerating aging. Senescence-associated-β-galactosidase (SA-β-gal) is a marker of aging, and β-hydroxybutyric acid treatment can reduce SA-β-gal activity to alleviate cellular senescence and damage. In addition, CCAAT/enhancer-binding protein-α, transforming growth factor-β signaling, glycogen synthase kinase-3β, cycle-dependent kinase, programmed cell death protein 1, and plasminogen activator inhibitor-1 are closely related to aging. The absence or elevation of these factors can affect aging through different mechanisms. Podocyte injury is not an independent process, and injured podocytes interact with the surrounding epithelial cells or other kidney cells to mediate the injury or loss of podocytes. In this review, we discuss the manifestations, molecular mechanisms, biomarkers, and therapeutic drugs for podocyte senescence. We included elamipretide, lithium, calorie restriction, rapamycin; and emerging treatment strategies, such as gene and immune therapies. More importantly, we summarize how podocyte interact with other kidney cells.

Nandrolone decanoate induced kidney injury through miRNA-146a targeting IRAK1 and TRAF6 via activation of the NF-κB pathway: The effect of moderate exercise

Anabolic-androgenic steroids (AAS) abuse is linked to some abnormalities in several tissues including the kidney. However, the precise molecular mediators involved in AAS-induced kidney disorder remain elusive. The main objective of the present study was to investigate the effect of Nandrolone decanoate on kidney injury alone or in combination with moderate exercise and its related mechanisms. Thirty-two male Wistar rats were subdivided randomly into four groups. control (Con), Nandrolone (10 mg/kg)(N), Exercise (Exe), Nandrolone + Exercise (N+Exe). RESULTS: After 6 weeks, nandrolone treatment led to a significant increase in functional parameters such as serum cystatin c, urea, creatinine, albuminuria and Albumin/ creatinine ratio indicating kidney dysfunction. Moreover, nandrolone treatment increased vacuolization, focal inflammation, hemorragia, cast formation fibrosis in the renal tissue of rats. miRNA-146a increased in kidney tissue after nandrolone exposure by using RT-PCR which may be considered idealtheranomiRNAcandidates for diagnosis and treatment. Western blotting indicated that IRAK1, TRAF6, TNF-α, NF-κB, iNOS and TGF-β protein expressions were considerably elevated in the kidneys of nandrolone treated rats. Moderate exercise could alleviate the renal dysfunction, histological abnormalities and aforementioned proteins. Our findings suggested that nandrolone consumption can cause damage to kidney tissue probably through miRNA-146a targeting IRAK1 and TRAF6 via activation of the NF-κB and TGF-β pathway. These results provide future lines of research in the identification of theranoMiRNAs related to nandrolone treatment, which can be ameliorated by moderate exercise.

Exosomal let-7b-5p deriving from parietal epithelial cells attenuate renal fibrosis through suppression of TGFβR1 and ARID3a in obstructive kidney disease

As renal progenitor cells, parietal epithelial cells (PECs) have demonstrated multilineage differentiation potential in response to kidney injury. However, the function of exosomes derived from PECs has not been extensively explored. Immunofluorescent staining of Claudin-1 was used to identify primary PECs isolated from mouse glomeruli. Transmission electron microscopy, nanoparticle tracking analysis, and western blotting were used to characterize the properties of PECs-derived exosomes (PEC-Exo). The therapeutic role of PEC-Exo in tubulointerstitial fibrosis was investigated in the unilateral ureteral obstruction (UUO) mouse model and TGF-β1-stimulated HK-2 cells. High-throughput miRNA sequencing was employed to profile PEC-Exo miRNAs. One of the most enriched miRNAs in PEC-Exo was knocked down by transfecting miRNA inhibitor, and then we investigated whether this candidate miRNA was involved in PEC-Exo-mediated tubular repair. The primary PECs expressed Claudin-1, PEC-Exo was homing to obstructed kidney, and TGF-β1 induced HK-2 cells. PEC-Exo significantly alleviated renal inflammation and ameliorated tubular fibrosis both in vivo and in vitro. Mechanistically, let-7b-5p, highly enriched in PEC-Exo, downregulated the protein levels of transforming growth factor beta receptor 1(TGFβR1) and AT-Rich Interaction Domain 3A(ARID3a) in tubular epithelial cells (TECs), leading to the inhibition of p21 and p27 to restoring cell cycle. Furthermore, administration of let-7b-5p agomir mitigated renal fibrosis in vivo. Our findings demonstrated that PEC-derived exosomes significantly repressed the expression of TGFβR1 and ARID3a by delivering let-7b-5p, thereby alleviating renal fibrosis. This study provides novel insights into the role of PEC-Exo in the repair of kidney injury and new ideas for renal fibrosis intervention.

Targeting the epidermal growth factor receptor (EGFR/ErbB) for the potential treatment of renal pathologies

Epidermal growth factor receptor (EGFR), which is referred to as ErbB1/HER1, is the prototype of the EGFR family of receptor tyrosine kinases which also comprises ErbB2 (Neu, HER2), ErbB3 (HER3), and ErbB4 (HER4). EGFR, along with other ErbBs, is expressed in the kidney tubules and is physiologically involved in nephrogenesis and tissue repair, mainly following acute kidney injury. However, its sustained activation is linked to several kidney pathologies, including diabetic nephropathy, hypertensive nephropathy, glomerulonephritis, chronic kidney disease, and renal fibrosis. This review aims to provide a summary of the recent findings regarding the consequences of EGFR activation in several key renal pathologies. We also discuss the potential interplay between EGFR and the reno-protective angiotensin-(1-7) (Ang-(1-7), a heptapeptide member of the renin-angiotensin-aldosterone system that counter-regulates the actions of angiotensin II. Ang-(1-7)-mediated inhibition of EGFR transactivation might represent a potential mechanism of action for its renoprotection. Our review suggests that there is a significant body of evidence supporting the potential inhibition of EGFR/ErbB, and/or administration of Ang-(1-7), as potential novel therapeutic strategies in the treatment of renal pathologies. Thus, EGFR inhibitors such as Gefitinib and Erlinotib that have an acceptable safety profile and have been clinically used in cancer chemotherapy since their FDA approval in the early 2000s, might be considered for repurposing in the treatment of renal pathologies.

Novel Peptide DR3penA as a Low-Toxicity Antirenal Fibrosis Agent by Suppressing the TGF-β1/miR-212-5p/Low-Density Lipoprotein Receptor Class a Domain Containing 4/Smad Axis

Renal fibrosis is a complex pathological process that contributes to the development of chronic kidney disease due to various risk factors. Conservative treatment to curb progression without dialysis or renal transplantation is widely applicable, but its effectiveness is limited. Here, the inhibitory effect of the novel peptide DR3penA (DHα-(4-pentenyl)-AlaNPQIR-NH2), which was developed by our group, on renal fibrosis was assessed in cells and mice with established fibrosis and fibrosis triggered by transforming growth factor-β1 (TGF-β1), unilateral ureteral obstruction, and repeated low-dose cisplatin. DR3penA preserved renal function and ameliorated renal fibrosis at a dose approximately 100 times lower than that of captopril, which is currently used in the clinic. DR3penA also significantly reduced existing fibrosis and showed similar efficacy after subcutaneous or intraperitoneal injection. Mechanistically, DR3penA repressed TGF-β1 signaling via miR-212-5p targeting of low-density lipoprotein receptor class a domain containing 4, which interacts with Smad2/3. In addition to having good pharmacological effects, DR3penA could preferentially target injured kidneys and exhibited low toxicity in acute and chronic toxicity experiments. These results unveil the advantages of DR3penA regarding efficacy and toxicity, making it a potential candidate compound for renal fibrosis therapy.

microRNA Expression Profile in Obesity-Induced Kidney Disease Driven by High-Fat Diet in Mice

Obesity is one of the main causes of chronic kidney disease; however, the precise molecular mechanisms leading to the onset of kidney injury and dysfunction in obesity-associated nephropathy remain unclear. The present study aimed to unveil the kidney microRNA (miRNA) expression profile in a model of obesity-induced kidney disease in C57BL/6J mice using next-generation sequencing (NGS) analysis. High-fat diet (HFD)-induced obesity led to notable structural alterations in tubular and glomerular regions of the kidney, increased renal expression of proinflammatory and profibrotic genes, as well as an elevated renal expression of genes involved in cellular lipid metabolism. The miRNA sequencing analysis identified a set of nine miRNAs differentially expressed in the kidney upon HFD feeding, with miR-5099, miR-551b-3p, miR-223-3p, miR-146a-3p and miR-21a-3p showing the most significant differential expression between standard diet (STD) and HFD mice. A validation analysis showed that the expression levels of miR-5099, miR-551b-3p and miR-146a-3p were consistent with NGS results, while Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses revealed that these three validated miRNAs modulated target genes involved in metabolic and adipocytokine pathways, fatty acid and lipid metabolism, and inflammatory, senescence and profibrotic pathways. Our results suggest that differentially expressed miRNAs play pivotal roles in the intricate pathophysiology of obesity-associated kidney disease and could potentially create novel treatment strategies to counteract the deleterious effects of obesity on kidney function.

MCPIP1 Inhibits Hepatic Stellate Cell Activation in Autocrine and Paracrine Manners, Preventing Liver Fibrosis

BACKGROUND & AIMS

Hepatic fibrosis is characterized by enhanced deposition of extracellular matrix (ECM), which results from the wound healing response to chronic, repeated injury of any etiology. Upon injury, hepatic stellate cells (HSCs) activate and secrete ECM proteins, forming scar tissue, which leads to liver dysfunction. Monocyte-chemoattractant protein-induced protein 1 (MCPIP1) possesses anti-inflammatory activity, and its overexpression reduces liver injury in septic mice. In addition, mice with liver-specific deletion of Zc3h12a develop features of primary biliary cholangitis. In this study, we investigated the role of MCPIP1 in liver fibrosis and HSC activation.

METHODS

We analyzed MCPIP1 levels in patients' fibrotic livers and hepatic cells isolated from fibrotic murine livers. In vitro experiments were conducted on primary HSCs, cholangiocytes, hepatocytes, and LX-2 cells with MCPIP1 overexpression or silencing.

RESULTS

MCPIP1 levels are induced in patients' fibrotic livers compared with their nonfibrotic counterparts. Murine models of fibrosis revealed that its level is increased in HSCs and hepatocytes. Moreover, hepatocytes with Mcpip1 deletion trigger HSC activation via the release of connective tissue growth factor. Overexpression of MCPIP1 in LX-2 cells inhibits their activation through the regulation of TGFB1 expression, and this phenotype is reversed upon MCPIP1 silencing.

CONCLUSIONS

We demonstrated that MCPIP1 is induced in human fibrotic livers and regulates the activation of HSCs in both autocrine and paracrine manners. Our results indicate that MCPIP1 could have a potential role in the development of liver fibrosis.

Role of Epigenetic Changes in the Pathophysiology of Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) is a global health issue. Epigenetic changes play an important role in the pathogenesis of this disease.

Summary

DKD is currently the leading cause of kidney failure worldwide. Although much is known about the pathophysiology of DKD, the research field of epigenetics is relatively new. Several recent studies have demonstrated that diabetes-induced dysregulation of epigenetic mechanisms alters the expression of pathological genes in kidney cells. If these changes persist for a long time, the so-called "metabolic memory" could be established. In this review, we highlight diabetes-induced epigenetic modifications associated with DKD. While there is a substantial amount of literature on epigenetic changes, only a few studies describe the underlying molecular mechanisms. Detailed analyses have shown that epigenetic changes play an important role in known pathological features of DKD, such as podocyte injury, fibrosis, accumulation of extracellular matrix, or oxidative injury, all of which contribute to the pathophysiology of disease. The transforming growth factor-β plays a key role as it is involved in all-mentioned epigenetic types of regulation.

Key Messages

Epigenetic is crucial for the development and progression of DKD, but the detailed molecular mechanisms have to be further analyzed more in detail.

The crosstalk between glomerular endothelial cells and podocytes controls their responses to metabolic stimuli in diabetic nephropathy

In diabetic nephropathy (DN), glomerular endothelial cells (GECs) and podocytes undergo pathological alterations, which are influenced by metabolic changes characteristic of diabetes, including hyperglycaemia (HG) and elevated methylglyoxal (MGO) levels. However, it remains insufficiently understood what effects these metabolic factors have on GEC and podocytes and to what extent the interactions between the two cell types can modulate these effects. To address these questions, we established a co-culture system in which GECs and podocytes were grown together in close proximity, and assessed transcriptional changes in each cell type after exposure to HG and MGO. We found that HG and MGO had distinct effects on gene expression and that the effect of each treatment was markedly different between GECs and podocytes. HG treatment led to upregulation of "immediate early response" genes, particularly those of the EGR family, as well as genes involved in inflammatory responses (in GECs) or DNA replication/cell cycle (in podocytes). Interestingly, both HG and MGO led to downregulation of genes related to extracellular matrix organisation in podocytes. Crucially, the transcriptional responses of GECs and podocytes were dependent on their interaction with each other, as many of the prominently regulated genes in co-culture of the two cell types were not significantly changed when monocultures of the cells were exposed to the same stimuli. Finally, the changes in the expression of selected genes were validated in BTBR ob/ob mice, an established model of DN. This work highlights the molecular alterations in GECs and podocytes in response to the key diabetic metabolic triggers HG and MGO, as well as the central role of GEC-podocyte crosstalk in governing these responses.

Text mining-based identification of promising miRNA biomarkers for diabetes mellitus

Introduction

MicroRNAs (miRNAs) are small, non-coding RNAs that play a critical role in diabetes development. While individual studies investigating the mechanisms of miRNA in diabetes provide valuable insights, their narrow focus limits their ability to provide a comprehensive understanding of miRNAs' role in diabetes pathogenesis and complications.

Methods

To reduce potential bias from individual studies, we employed a text mining-based approach to identify the role of miRNAs in diabetes and their potential as biomarker candidates. Abstracts of publications were tokenized, and biomedical terms were extracted for topic modeling. Four machine learning algorithms, including Naïve Bayes, Decision Tree, Random Forest, and Support Vector Machines (SVM), were employed for diabetes classification. Feature importance was assessed to construct miRNA-diabetes networks.

Results

Our analysis identified 13 distinct topics of miRNA studies in the context of diabetes, and miRNAs exhibited a topic-specific pattern. SVM achieved a promising prediction for diabetes with an accuracy score greater than 60%. Notably, miR-146 emerged as one of the critical biomarkers for diabetes prediction, targeting multiple genes and signal pathways implicated in diabetic inflammation and neuropathy.

Conclusion

This comprehensive approach yields generalizable insights into the network miRNAs-diabetes network and supports miRNAs' potential as a biomarker for diabetes.

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.

Non-coding RNAs and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a worldwide disease with rapidly increasing prevalence. This complex disorder caused by interplay between genetic predisposition factors, early developmental elements, diet and inactive lifestyle. Several researches have shown impact of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in the pathogenesis of this disorder. Several miRNAs such as miR-126, miR-222-3p, miR-182, let-7b-5p, and miR-1-3p have been down-regulated in different biological sources of patients with T2DM. Some other miRNAs including miR-21, miR-30d, miR-148a-3p, miR-146b and miR-486 have the opposite trends. In addition, a number of lncRNAs such as LY86-AS, HCG27_201, VIM-AS1, CTBP1-AS2, CASC2, GAS5, LINC-PINT, and MALAT1 have been altered in the peripheral blood, serum samples or tissues obtained from patients with T2DM. Taken together, both miRNAs and lncRNAs contribute to the development of T2DM and might be applied as markers or therapeutic molecules for this disorder.

Urinary microRNA in Diabetic Kidney Disease: A Literature Review

Diabetic kidney disease is the most common primary disease of end-stage kidney disease globally; however, a sensitive and accurate biomarker to predict this disease remains awaited. microRNAs are endogenous single-stranded noncoding RNAs that have intervened in different post-transcriptional regulations of various cellular biological functions. Previous literatures have reported its potential role in the pathophysiology of diabetic kidney disease, including regulation of Transforming Growth Factor-β1-mediated fibrosis, extracellular matrix and cell adhesion proteins, cellular hypertrophy, growth factor, cytokine production, and redox system activation. Urinary microRNAs have emerged as a novel, non-invasive liquid biopsy for disease diagnosis. In this review, we describe the available experimental and clinical evidence of urinary microRNA in the context of diabetic kidney disease and discuss the future application of microRNA in routine practice.

Pediatric Diabetic Nephropathy: Novel Insights from microRNAs

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

Association of MicroRNA-146a with Type 1 and 2 Diabetes and their Related Complications

Most medical investigations have found a reduced blood level of miR-146a in type 2 diabetes (T2D) patients, suggesting an important role for miR-146a (microRNA-146a) in the etiology of diabetes mellitus (DM) and its consequences. Furthermore, injection of miR-146a mimic has been confirmed to alleviate diabetes mellitus in diabetic animal models. In this line, deregulation of miR-146a expression has been linked to the progression of nephropathy, neuropathy, wound healing, olfactory dysfunction, cardiovascular disorders, and retinopathy in diabetic patients. In this review, besides a comprehensive review of the function of miR-146a in DM, we discussed new findings on type 1 (T1MD) and type 2 (T2DM) diabetes mellitus, highlighting the discrepancies between clinical and preclinical investigations and elucidating the biological pathways regulated through miR-146a in DM-affected tissues.

Podocyte-specific deletion of miR-146a increases podocyte injury and diabetic kidney disease

Diabetic glomerular injury is a major complication of diabetes mellitus and is the leading cause of end stage renal disease (ESRD). Healthy podocytes are essential for glomerular function and health. Injury or loss of these cells results in increased proteinuria and kidney dysfunction and is a common finding in various glomerulopathies. Thus, mechanistic understanding of pathways that protect podocytes from damage are essential for development of future therapeutics. MicroRNA-146a (miR-146a) is a negative regulator of inflammation and is highly expressed in myeloid cells and podocytes. We previously reported that miR-146a levels are significantly reduced in the glomeruli of patients with diabetic nephropathy (DN). Here we report generation of mice with selective deletion of miR-146a in podocytes and use of these mice in models of glomerular injury. Induction of glomerular injury in C57BL/6 wildtype mice (WT) and podocyte-specific miR-146a knockout (Pod-miR146a-/-) animals via administration of low-dose lipopolysaccharide (LPS) or nephrotoxic serum (NTS) resulted in increased proteinuria in the knockout mice, suggesting that podocyte-expressed miR-146a protects these cells, and thus glomeruli, from damage. Furthermore, induction of hyperglycemia using streptozotocin (STZ) also resulted in an accelerated development of glomerulopathy and a rapid increase in proteinuria in the knockout animals, as compared to the WT animals, further confirming the protective role of podocyte-expressed miR-146a. We also confirmed that the direct miR-146a target, ErbB4, was significantly upregulated in the diseased glomeruli and erlotinib, an ErbB4 and EGFR inhibitor, reducedits upregulation and the proteinuria in treated animals. Primary miR146-/- podocytes from these animals also showed a basally upregulated TGFβ-Smad3 signaling in vitro. Taken together, this study shows that podocyte-specific miR-146a is imperative for protecting podocytes from glomerular damage, via modulation of ErbB4/EGFR, TGFβ, and linked downstream signaling.

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.

Pathogenic Role of MicroRNA Dysregulation in Podocytopathies

MicroRNAs (miRNAs) participate in the regulation of various important biological processes by regulating the expression of various genes at the post-transcriptional level. Podocytopathies are a series of renal diseases in which direct or indirect damage of podocytes results in proteinuria or nephrotic syndrome. Despite decades of research, the exact pathogenesis of podocytopathies remains incompletely understood and effective therapies are still lacking. An increasing body of evidence has revealed a critical role of miRNAs dysregulation in the onset and progression of podocytopathies. Moreover, several lines of research aimed at improving common podocytopathies diagnostic tools and avoiding invasive kidney biopsies have also identified circulating and urine miRNAs as possible diagnostic and prognostic biomarkers for podocytopathies. The present review mainly aims to provide an updated overview of the recent achievements in research on the potential applicability of miRNAs involved in renal disorders related to podocyte dysfunction by laying particular emphasis on focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), membranous nephropathy (MN), diabetic kidney disease (DKD) and IgA nephropathy (IgAN). Further investigation into these dysregulated miRNAs will not only generate novel insights into the mechanisms of podocytopathies, but also might yield novel strategies for the diagnosis and therapy of this disease.

The Role of Epigenetic Modifications in Late Complications in Type 1 Diabetes

Type 1 diabetes is a chronic autoimmune disease in which the destruction of pancreatic β cells leads to hyperglycemia. The prevention of hyperglycemia is very important to avoid or at least postpone the development of micro- and macrovascular complications, also known as late complications. These include diabetic retinopathy, chronic renal failure, diabetic neuropathy, and cardiovascular diseases. The impact of long-term hyperglycemia has been shown to persist long after the normalization of blood glucose levels, a phenomenon known as metabolic memory. It is believed that epigenetic mechanisms such as DNA methylation, histone modifications, and microRNAs, play an important role in metabolic memory. The aim of this review is to address the impact of long-term hyperglycemia on epigenetic marks in late complications of type 1 diabetes.

Micro-ribonucleic acid modulation with oxidative stress and inflammation in patients with type 2 diabetes mellitus - a review article

In parallel with the rapid growth of obesity, there is also an increase in the prevalence of type 2 diabetes mellitus (T2D) worldwide. Due to its complications, cardiovascular diseases are the leading cause of death in those patients. In the last two decades, special attention has been given to oxidative stress and inflammation, as the underlying mechanisms related to T2D occurrence and progression. Moreover, micro-ribonucleic acids (miRNAs) as new genetic biomarkers take an important place in the investigation of different metabolic pathways of insulin signaling. In this review article, we discuss microRNA modulation with oxidative stress and inflammation in patients with T2D. Better insight into the novel potential therapeutic targets for treatment of diabetes and its complications is of utmost importance for public health.

MicroRNAs and their delivery in diabetic fibrosis

The global prevalence of diabetes mellitus was estimated to be 463 million people in 2019 and is predicted to rise to 700 million by 2045. The associated financial and societal costs of this burgeoning epidemic demand an understanding of the pathology of this disease, and its complications, that will inform treatment to enable improved patient outcomes. Nearly two decades after the sequencing of the human genome, the significance of noncoding RNA expression is still being assessed. The family of functional noncoding RNAs known as microRNAs regulates the expression of most genes encoded by the human genome. Altered microRNA expression profiles have been observed both in diabetes and in diabetic complications. These transcripts therefore have significant potential and novelty as targets for therapy, therapeutic agents and biomarkers.

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.

Peripheral Blood circRNA Microarray Profiling Identities hsa_circ_0001831 and hsa_circ_0000867 as Two Novel circRNA Biomarkers for Early Type 2 Diabetic Nephropathy

PURPOSE

Type 2 diabetes mellitus (T2DM) increases the incidence of diabetic nephropathy (DN) and eventually progresses to end-stage renal disease. Circular RNAs (circRNAs) are a class of non-coding RNAs that are promising as diagnostic biomarkers and therapeutic targets for human diseases. The aim of this study was to analyze the differential expression of circRNAs (DECs) in peripheral blood from patients with early type 2 diabetic nephropathy (ET2DN), T2DM and controls, which will facilitate to discover some new biomarkers for ET2DN.

PATIENTS AND METHODS

Twenty ET2DN patients, 20 T2DM patients, and 20 normal controls were included in this study. Blood samples from 3 random subjects of age- and sex-matched patients in each group, respectively, were used to detect circRNA expression profiles by circRNA microarray, and the circRNA expression of remaining subjects was validated by real-time quantitative polymerase chain reaction (qRT-PCR). Further functional assessment was performed by bioinformatic tools.

RESULTS

There were 586 DECs in ET2DN vs T2DM group (249 circRNAs were upregulated and 337 circRNAs were downregulated); 176 circRNAs were upregulated and 101 circRNAs were downregulated in T2DM vs control group; 57 circRNAs were upregulated and 5 circRNAs were downregulated in ET2DN vs control group. The functional and pathway enrichment of DECs were analyzed by GO and KEGG. qRT-PCR results revealed that hsa_circ_0001831 and hsa_circ_0000867 were significantly upregulated in ET2DN group compared to both of T2DM and control group. The ROC curve demonstrated that hsa_circ_0001831 and hsa_circ_0000867 have high sensitivity and specificity associated with ET2DN.

CONCLUSION

Our study showed the expression profiles of circRNAs in ET2DN patients and demonstrated that hsa_circ_0001831 and hsa_circ_0000867 can be used as novel diagnostic biomarkers for ET2DN.

Diabetic Complications: An Update on Pathobiology and Therapeutic Strategies

Despite the advent of novel therapies which manage and control diabetes well, the increased risk of morbidity and mortality in diabetic subjects is associated with the devastating secondary complications it produces. Long-standing diabetes majorly drives cellular and molecular alterations, which eventually damage both small and large blood vessels. The complications are prevalent both in type I and type II diabetic subjects. The microvascular complications include diabetic neuropathy, diabetic nephropathy, diabetic retinopathy, while the macrovascular complications include diabetic heart disease and stroke. The current therapeutic strategy alleviates the complications to some extent but does not cure or prevent them. Also, the recent clinical trial outcomes in this field are disappointing. Success in the drug discovery of diabetic complications may be achieved by a better understanding of the underlying pathophysiology and by recognising the crucial factors contributing to the development and progression of the disease. In this review, we discuss the well-studied cellular mechanisms leading to the development and progression of diabetic complications. In addition, we also highlight the various therapeutic paradigms currently in clinical practice.

Expression of Circulating MicroRNAs and Myokines and Interactions with Serum Osteopontin in Type 2 Diabetic Patients with Moderate and Poor Glycemic Control: A Biochemical and Molecular Study

BACKGROUND

Cellular miRNAs are expressed in tissue fluids with sufficient amounts and were identified as potential molecular targets for studying the physiological mechanisms and correlations with many human diseases particularly diabetes. However, molecular-based changes among older adults with diabetes mellitus (DM) are rarely fully elucidated.

AIM

This study is aimed at identifying circulating miRNAs, which hold the potential to serve as biomarkers for the immune-inflammatory changes in older T2D patients with moderate and poor glycemic control status. In addition, the association of both myokines and osteopontin (OPN) levels with circulating miRNAs was identified.

METHODS

A total of 80 subjects aged 20-80 years were invited during the period of October 2017-May 2018 to participate in this descriptive cross-sectional study. All subjects were diagnosed with T2D for more than 5 years. Subjects were grouped based on glycemic control (HbA1c values) into two groups: moderate glycemic control (>7-8% HbA1c, no = 30) and poor glycemic control (>8% HbA1c, no = 50), respectively. Diabetic control parameters, fasting blood sugar (FS), HbA1c, fasting insulin (IF), insulin resistance (IR), HOMA-IR, inflammatory cytokines (IL-6, IL-8, IL-18, IL-23, TNF-α, and CRP), osteopontin, and myokines (adropin and irisin) were estimated by colorimetric and immune ELISA assays, respectively. In addition, real-time RT-PCR analysis was performed to evaluate the expression of circulating miRNAs, miR-146a and miR-144, in the serum of all diabetic subjects.

RESULTS

In this study, T2D patients with poor glycemic control showed a significant increase in the serum levels of IL-6, IL-8, IL-18, IL-23, TNF-α, CRP, and OPN and a reduction in the levels of myokines, adropin and irisin, compared to patients with moderate glycemic control. The results obtained are significantly correlated with the severity of diabetes measured by HbA1c, FS, IF, and HOMA-IR. In addition, baseline expression of miR-146a is significantly reduced and miR-144 is significantly increased in T2D patients with poor glycemic control compared to those with moderate glycemic control. In all diabetic groups, the expression of miR-146a and miR-144 is significantly correlated with diabetic controls, inflammatory cytokines, myokines, and serum levels of OPN. Respective of gender, women with T2D showed more significant change in the expressed miRNAs, inflammatory cytokines, OPN, and serum myokine markers compared to men. ROC analysis identified AUC cutoff values of miR-146a, miR-144, adropin, irisin, and OPN expression levels with considerable specificity and sensitivity which recommends the potential use of adropin, irisin, and OPN as diagnostic biomarkers for diabetes with varying glycemic control status.

CONCLUSION

In this study, molecular expression of certain microRNA species, such as miR-146a and miR-144, was identified and significantly associated with parameters of disease severity, HbA1c, inflammatory cytokines, myokines, and serum osteopontin in T2D patients with moderate and poor glycemic control. The AUC cutoff values of circulating miRNAs, miR-146a and miR-144; myokines, adropin and irisin; and serum OPN were significantly identified by ROC analysis which additionally recommends the potential use of these biomarkers, miR-146a, miR-144, adropin, irisin, and OPN, as diagnostic biomarkers with considerable specificity and sensitivity for diabetes in patients with varying glycemic control status.

MicroRNA 146a is associated with diabetic complications in type 1 diabetic patients from the EURODIAB PCS

Background

MicroRNA-146a-5p (miR-146a-5p) is a key regulator of inflammatory processes. Expression of miR-146a-5p is altered in target organs of diabetic complications and deficiency of miR-146a-5p has been implicated in their pathogenesis. We investigated if serum miR-146a-5p levels were independently associated with micro/macrovascular complications of type 1 diabetes (DM1).

Methods

A nested case–control study from the EURODIAB PCS of 447 DM1 patients was performed. Cases (n = 294) had one or more complications of diabetes, whereas controls (n = 153) did not have any complication. Total RNA was isolated from all subjects and miR-146a-5p levels measured by qPCR. Both the endogenous controls U6 snRNA and the spike (Cel-miR-39) were used to normalize the results. Logistic regression analysis was carried out to investigate the association of miR-146a-5p with diabetes complications.

Results

MiR-146a-5p levels were significantly lower in cases [1.15 (0.32–3.34)] compared to controls [1.74 (0.44–6.74) P = 0.039]. Logistic regression analysis showed that levels of miR-146a-5p in the upper quartile were inversely associated with reduced odds ratio (OR) of all complications (OR 0.34 [95% CI 0.14–0.76]) and particularly with cardiovascular diseases (CVD) (OR 0.31 [95% CI 0.11–0.84]) and diabetic retinopathy (OR 0.40 [95% CI 0.16–0.99]), independently of age, sex, diabetes duration, A1c, hypertension, AER, eGFR, NT-proBNP, and TNF-α.

Conclusions

In this large cohort of DM1 patients, we reported an inverse and independent association of miR-146a-5p with diabetes chronic complications and in particular with CVD and retinopathy, suggesting that miR-146a-5p may be a novel candidate biomarker of DM1 complications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03142-4.

Identification of miRNA-mRNA network and immune-related gene signatures in IgA nephropathy by integrated bioinformatics analysis

BACKGROUND

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide, and its diagnosis depends mainly on renal biopsy. However, there is no specific treatment for IgAN. Moreover, its causes and underlying molecular events require further exploration.

METHODS

The expression profiles of GSE64306 and GSE93798 were downloaded from the Gene Expression Omnibus (GEO) database and used to identify the differential expression of miRNAs and genes, respectively. The StarBase and TransmiR databases were employed to predict target genes and transcription factors of the differentially expressed miRNAs (DE-miRNAs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were conducted to predict biological functions. A comprehensive analysis of the miRNA-mRNA regulatory network was constructed, and protein-protein interaction (PPI) networks and hub genes were identified. CIBERSORT was used to examine the immune cells in IgAN, and correlation analyses were performed between the hub genes and infiltrating immune cells.

RESULTS

Four downregulated miRNAs and 16 upregulated miRNAs were identified. Forty-five and twelve target genes were identified for the upregulated and downregulated DE-miRNAs, respectively. CDKN1A, CDC23, EGR1, HIF1A, and TRIM28 were the hub genes with the highest degrees of connectivity. CIBERSORT revealed increases in the numbers of activated NK cells, M1 and M2 macrophages, CD4 naive T cells, and regulatory T cells in IgAN. Additionally, HIF1A, CDC23, TRIM28, and CDKN1A in IgAN patients were associated with immune cell infiltration.

CONCLUSIONS

A potential miRNA-mRNA regulatory network contributing to IgAN onset and progression was successfully established. The results of the present study may facilitate the diagnosis and treatment of IgAN by targeting established miRNA-mRNA interaction networks. Infiltrating immune cells may play significant roles in IgAN pathogenesis. Future studies on these immune cells may help guide immunotherapy for IgAN patients.

Construction and Bioinformatics Analysis of the miRNA-mRNA Regulatory Network in Diabetic Nephropathy

Background

MicroRNA (miRNA) has been confirmed to be involved in the occurrence, development, and prevention of diabetic nephropathy (DN), but its mechanism of action is still unclear.

Objective

With the help of the GEO database, bioinformatics methods are used to explore the miRNA-mRNA regulatory relationship pairs related to diabetic nephropathy and explain their potential mechanisms of action.

Methods

The DN-related miRNA microarray dataset (GSE51674) and mRNA expression dataset (GSE30122) are downloaded through the GEO database, online analysis tool GEO2R is used for data differential expression analysis, TargetScan, miRTarBase, and miRDB databases are used to predict potential downstream target genes regulated by differentially expressed miRNAs, and intersection with differential genes is used to obtain candidate target genes. According to the regulatory relationship between miRNA and mRNA, the miRNA-mRNA relationship pair is clarified, and the miRNA-mRNA regulatory network is constructed using Cytoscape. DAVID is used to perform GO function enrichment analysis and KEGG pathway analysis of candidate target genes. By GeneMANIA prediction of miRNA target genes and coexpressed genes, the protein interaction network is constructed. Results and Conclusions. A total of 67 differentially expressed miRNAs were screened in the experiment, of which 42 were upregulated and 25 were downregulated; a total of 448 differentially expressed mRNAs were screened, of which 93 were upregulated and 355 were downregulated. Using TargetScan, miRTarBase, and miRDB databases to predict downstream targets of differentially expressed miRNAs, 2283 downstream target genes coexisting in 3 databases were predicted to intersect with differentially expressed mRNAs to obtain 96 candidate target genes. Finally, 44 miRNA-mRNA relationship pairs consisting of 12 differentially expressed miRNAs and 27 differentially expressed mRNAs were screened out; further analysis showed that miRNA regulatory network genes may participate in the occurrence and development of diabetic nephropathy through PI3K/Akt, ECM-receptor interaction pathway, and RAS signaling pathway.

MiR-539-5p inhibits the inflammatory injury in septic H9c2 cells by regulating IRAK3

Background

MicroRNAs (miRNAs) have been confirmed to play a potential role in sepsis, but little is known about their role in sepsis-induced cardiomyopathy (SIC).

Methods

The model of septic cardiomyopathy was constructed with H9c2 cells induced by lipopolysaccharide (LPS), and the expression of miR-539-5p was detected by qRT-PCR assay. ELISA, CCK-8, EdU TUNEL analysis were performed to evaluate the role of miR-539-5p in inflammation response, viability, proliferation and apoptosis of LPS-treated H9c2 cells. Moreover, miRWalk and TargetScan prediction, and dual-luciferase reporter gene assays were carried out to predict and confirm the target of miR-539-5p. Furthermore, the effects of target on inflammation response, proliferation and apoptosis of LPS-induced H9c2 cells mediated by miR-539-5p was further explored.

Results

The expression of miR-539-5p was obviously down-regulated in LPS-induced H9c2 cells. In addition, over-expression of miR-539-5p significantly inhibited the inflammation response, promoted viability and proliferation, and suppressed apoptosis of LPS-treated H9c2 cells. Moreover, interleukin-1 receptor-associated kinase 3 (IRAK3) was verified as a target of miR-539-5p by dual-luciferase reporter gene assay. Besides, IRAK3 was highly expressed in H9c2 cells transfected with miR-539-5p inhibitor detected with qRT-PCR and western blot assays. Furthermore, over-expression of IRAK3 partially weakened the effects of miR-539-5p mimic on the inflammation response, proliferation and apoptosis of LPS-induced H9c2 cells.

Conclusions

MiR-539-5p potentially plays an important role in the pathogenesis of LPS-induced sepsis by targeting IRAK3, suggesting that miR-539-5p may be a potential new target for the treatment of LPS-induced sepsis.

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.

Deiodinase-3 is a thyrostat to regulate podocyte homeostasis

BACKGROUND

Nephrotic syndrome (NS) is associated with kidney podocyte injury and may occur as part of thyroid autoimmunity such as Graves' disease. Therefore, the present study was designed to ascertain if and how podocytes respond to and regulate the input of biologically active thyroid hormone (TH), 3,5,3'-triiodothyronine (T3); and also to decipher the pathophysiological role of type 3 deiodinase (D3), a membrane-bound selenoenzyme that inactivates TH, in kidney disease.

METHODS

To study D3 function in healthy and injured (PAN, puromycin aminonucleoside and LPS, Lipopolysaccharide-mediated) podocytes, immunofluorescence, qPCR and podocyte-specific D3 knockout mouse were used. Surface plasmon resonance (SPR), co-immunoprecipitation and Proximity Ligation Assay (PLA) were used for the interaction studies.

FINDINGS

Healthy podocytes expressed D3 as the predominant deiodinase isoform. Upon podocyte injury, levels of Dio3 transcript and D3 protein were dramatically reduced both in vitro and in the LPS mouse model of podocyte damage. D3 was no longer directed to the cell membrane, it accumulated in the Golgi and nucleus instead. Further, depleting D3 from the mouse podocytes resulted in foot process effacement and proteinuria. Treatment of mouse podocytes with T3 phenocopied the absence of D3 and elicited activation of αvβ3 integrin signaling, which led to podocyte injury. We also confirmed presence of an active thyroid stimulating hormone receptor (TSH-R) on mouse podocytes, engagement and activation of which resulted in podocyte injury.

INTERPRETATION

The study provided a mechanistic insight into how D3-αvβ3 integrin interaction can minimize T3-dependent integrin activation, illustrating how D3 could act as a renoprotective thyrostat in podocytes. Further, injury caused by binding of TSH-R with TSH-R antibody, as found in patients with Graves' disease, explained a plausible link between thyroid disorder and NS.

FUNDING

This work was supported by American Thyroid Association (ATA-2018-050.R1).

Adding a "Notch" to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

Dysregulation of the Notch pathway is implicated in the pathophysiology of cardiovascular diseases (CVDs), but, as of today, therapies based on the re-establishing the physiological levels of Notch in the heart and vessels are not available. A possible reason is the context-dependent role of Notch in the cardiovascular system, which would require a finely tuned, cell-specific approach. MicroRNAs (miRNAs) are short functional endogenous, non-coding RNA sequences able to regulate gene expression at post-transcriptional levels influencing most, if not all, biological processes. Dysregulation of miRNAs expression is implicated in the molecular mechanisms underlying many CVDs. Notch is regulated and regulates a large number of miRNAs expressed in the cardiovascular system and, thus, targeting these miRNAs could represent an avenue to be explored to target Notch for CVDs. In this Review, we provide an overview of both established and potential, based on evidence in other pathologies, crosstalks between miRNAs and Notch in cellular processes underlying atherosclerosis, myocardial ischemia, heart failure, calcification of aortic valve, and arrhythmias. We also discuss the potential advantages, as well as the challenges, of using miRNAs for a Notch-based approach for the diagnosis and treatment of the most common CVDs.

GPCR-ErbB transactivation pathways and clinical implications

Cell surface receptors including the epidermal growth factor receptor (EGFR) family and G-protein coupled receptors (GPCRs) play quintessential roles in physiology, and in diseases, including cardiovascular diseases. While downstream signaling from these individual receptor families has been well studied, the cross-talk between EGF and GPCR receptor families is still incompletely understood. Including members of both receptor families, the number of receptor and ligand combinations for unique interactions is vast, offering a frontier of pharmacologic targets to explore for preventing and treating disease. This molecular cross-talk, called receptor transactivation, is reviewed here with a focus on the cardiovascular system featuring the well-studied GPCR receptors, but also discussing less-studied receptors from both families for a broad understanding of context of expansile interactions, repertoire of cellular signaling, and disease consequences. Attention is given to cell type, level of chronicity, and disease context given that transactivation and comorbidities, including diabetes, hypertension, coronavirus infection, impact cardiovascular disease and health outcomes.

hsa-miR-199b-3p Prevents the Epithelial-Mesenchymal Transition and Dysfunction of the Renal Tubule by Regulating E-cadherin through Targeting KDM6A in Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. The association between epithelial-mesenchymal transition (EMT) and fibrosis is quite ascertained, but its link to eventual tubule dysfunction is missing. Here, we show that human microRNA- (hsa-miR-) 199b-3p protects renal tubules from diabetic-induced injury by repressing KDM6A, a histone lysine demethylase regulating E-cadherin expression. Lower E-cadherin expression is related to a higher level of KDM6A, while E-cadherin is promoted upon treatment with the KDM6A inhibitor GSK-J4 in both high glucose- (HG-) induced HK2 cells and the kidneys from streptozotocin- (STZ-) induced type 1 diabetic mice. However, overexpression or RNA silencing of E-cadherin fails to alter KDM6A expression. We also show that the upregulation of KDM6A is associated with the increased methylation level of the E-cadherin promoter. Then, the target prediction results and a dual-luciferase assay show that hsa-miR-199b-3p is a new miRNA that targets KDM6A. Overexpression of hsa-miR-199b-3p increases E-cadherin expression and prevents EMT through repressing KDM6A expression in HG-induced HK2 cells. In contrast, inhibitor-induced hsa-miR-199b-3p knockdown has opposite effects, as it decreases E-cadherin level and worsens EMT, accompanied by increased levels of KDM6A. Besides, Mir199b-knockout mice without mmu-miR-119b-3p expression exhibit more renal tubule dysfunction and more serious kidney tissue damage upon treatment with STZ. These results demonstrate that hsa-miR-199b-3p improves E-cadherin expression and prevents the progression of DN through targeting KDM6A. miR-199b-3p could be a future biomarker or target for the diagnosis or treatment of DN.

Glomerular Endothelial Cells Are the Coordinator in the Development of Diabetic Nephropathy

The prevalence of diabetes is consistently rising worldwide. Diabetic nephropathy is a leading cause of chronic renal failure. The present study aimed to explore the crosstalk among the different cell types inside diabetic glomeruli, including glomerular endothelial cells, mesangial cells, podocytes, and immune cells, by analyzing an online single-cell RNA profile (GSE131882) of patients with diabetic nephropathy. Differentially expressed genes in the glomeruli were processed by gene enrichment and protein-protein interactions analysis. Glomerular endothelial cells, as well as podocytes, play a critical role in diabetic nephropathy. A subgroup of glomerular endothelial cells possesses characteristic angiogenesis genes, indicating that angiogenesis takes place in the progress of diabetic nephropathy. Immune cells such as macrophages, T lymphocytes, B lymphocytes, and plasma cells also contribute to the disease progression. By using iTALK, the present study reports complicated cellular crosstalk inside glomeruli. Dysfunction of glomerular endothelial cells and immature angiogenesis result from the activation of both paracrine and autocrine signals. The present study reinforces the importance of glomerular endothelial cells in the development of diabetic nephropathy. The exploration of the signaling pathways involved in aberrant angiogenesis reported in the present study shed light on potential therapeutic target(s) for diabetic nephropathy.

Inhibition of miRNA-155 Alleviates High Glucose-Induced Podocyte Inflammation by Targeting SIRT1 in Diabetic Mice

OBJECTIVE

Microinflammation plays a crucial role in podocyte dysfunction in diabetic nephropathy, but its regulatory mechanism is still unclear. This study is aimed at discussing the mechanisms underlying the effect of miRNA-155 on podocyte injury to determine its potential as a therapeutic target.

METHODS

Cultured immortalized mouse podocytes and diabetic KK-Ay mice models were treated with a miR-155 inhibitor. Western blotting, real-time PCR, ELISA, immunofluorescence, and Luciferase reporter assay were used to analyze markers of inflammation cytokines and podocyte injury.

RESULTS

miRNA-155 was found to be highly expressed in serum and kidney tissue of mice with diabetic nephropathy and in cultured podocytes, accompanied by elevated levels of inflammatory factors. Inhibition of miRNA-155 can reduce proteinuria and ACR levels, diminish the secretion of inflammatory molecules, improve kidney function, inhibit podocyte foot fusion, and reverse renal pathological changes in diabetic nephropathy mice. Overexpression of miRNA-155 in vitro can increase inflammatory molecule production in podocytes and aggravates podocyte injury, while miRNA-155 inhibition suppresses inflammatory molecule production in podocytes and reduces podocyte injury. A luciferase assay confirmed that miRNA-155 could selectively bind to 3'-UTR of SIRT1, resulting in decreased SIRT1 expression. In addition, SIRT1 siRNA could offset SIRT1 upregulation and enhance inflammatory factor secretion in podocytes, induced by the miRNA-155 inhibitor.

CONCLUSIONS

These findings strongly support the hypothesis that miRNA-155 inhibits podocyte inflammation and reduces podocyte injury through SIRT1 silencing. miRNA-155 suppression therapy may be useful for the management of diabetic nephropathy.

Hydrogen Peroxide-Induced Senescence Reduces the Wound Healing-Promoting Effects of Mesenchymal Stem Cell-Derived Exosomes Partially via miR-146a

Mesenchymal stem cells (MSCs) have beneficial effects on wound healing. MSCs function through direct cell-cell communication or indirectly through paracrine secretion of exosomes. Here, we found that MSC-derived exosomes had pro-wound healing effects via promotion of angiogenesis; however, this promoting effect was significantly reduced when senescence was induced in parental MSCs by hydrogen peroxide (H₂O₂). Further experiments showed that decreased miR-146a expression in exosomes derived from senescent MSCs (s-exo) contributed to these findings. In vitro, the pro-angiogenic effect of s-exo on tube formation in human umbilical vein endothelial cells was significantly reduced compared with that of exosomes derived from control MSCs (c-exo). In vivo, higher tube numbers and longer tube lengths were observed in the c-exo group compared with the s-exo group. Using microarray analysis, we found that miR-146a level in s-exo was lower than that in c-exo. Knockdown of miR-146a in c-exo decreased its capacity to promote angiogenesis, and overexpression of miR-146a in s-exo partially rescued its impaired pro-angiogenic capacity, thereby confirming that downregulation of miR-146a contributed to the reduced pro-wound healing capacity of s-exo. Our study is the first to demonstrate that cell senescence induced by H₂O₂ alters the pro-angiogenic ability of exosomes by modulating the expression of exosomal miRNAs, especially miR-146a, thus providing new insights into the correlation between parental cell state and exosome content and function.

Epidermal Growth Factor Receptor: A Potential Therapeutic Target for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease worldwide and the major cause of renal failure among patients on hemodialysis. Numerous studies have demonstrated that transient activation of epidermal growth factor receptor (EGFR) pathway is required for promoting kidney recovery from acute injury whereas its persistent activation is involved in the progression of various chronic kidney diseases including DKD. EGFR-mediated pathogenesis of DKD is involved in hemodynamic alteration, metabolic disturbance, inflammatory response and parenchymal cellular dysfunction. Therapeutic intervention of this receptor has been available in the oncology setting. Targeting EGFR might also hold a therapeutic potential for DKD. Here we review the functional role of EGFR in the development of DKD, mechanisms involved and the perspective about use of EGFR inhibitors as a treatment for DKD.

MicroRNAs as Regulators of Immune and Inflammatory Responses: Potential Therapeutic Targets in Diabetic Nephropathy

Diabetic nephropathy (DN) is the principal cause of end-stage renal disease and results in high morbidity and mortality in patients, causing a large socioeconomic burden. Multiple factors, such as metabolic abnormalities, inflammation, immunoregulation and genetic predisposition, contribute to the pathogenesis of DN, but the exact mechanism is unclear, and the therapeutic strategies are not satisfactory. Accordingly, there is an unmet need for new therapeutic targets and strategies for DN. MicroRNAs (miRNAs) act as major epigenetic mechanisms that regulate gene expression and provide novel insights into our understanding of the molecular and signaling pathways that are associated with various diseases, including DN. Studies in the past decade have shown that different miRNAs affect the progression of DN by modulating different aspects of immune and inflammatory responses. Therefore, in this review, we summarized the pivotal roles of miRNAs in inflammatory and immune processes, with an integrative comprehension of the detailed signaling network. Additionally, we discussed the possibilities and significance of these miRNAs as therapeutic targets in the treatment of DN. This review will facilitate the identification of new therapeutic targets and novel strategies that can be translated into clinical applications for DN treatment.

Diabetic Nephropathy: Novel Molecular Mechanisms and Therapeutic Targets

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes mellitus and the leading cause of end-stage kidney disease. The standard treatments for diabetic patients are glucose and blood pressure control, lipid lowering, and renin-angiotensin system blockade; however, these therapeutic approaches can provide only partial renoprotection if started late in the course of the disease. One major limitation in developing efficient therapies for DN is the complex pathobiology of the diabetic kidney, which undergoes a set of profound structural, metabolic and functional changes. Despite these difficulties, experimental models of diabetes have revealed promising therapeutic targets by identifying pathways that modulate key functions of podocytes and glomerular endothelial cells. In this review we will describe recent advances in the field, analyze key molecular pathways that contribute to the pathogenesis of the disease, and discuss how they could be modulated to prevent or reverse DN.

miR-146a regulates insulin sensitivity via NPR3

The pathogenesis of obesity-related metabolic diseases has been linked to the inflammation of white adipose tissue (WAT), but the molecular interconnections are still not fully understood. MiR-146a controls inflammatory processes by suppressing pro-inflammatory signaling pathways. The aim of this study was to characterize the role of miR-146a in obesity and insulin resistance. MiR-146a^-/- mice were subjected to a high-fat diet followed by metabolic tests and WAT transcriptomics. Gain- and loss-of-function studies were performed using human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. Compared to controls, miR-146a^-/- mice gained significantly more body weight on a high-fat diet with increased fat mass and adipocyte hypertrophy. This was accompanied by exacerbated liver steatosis, insulin resistance, and glucose intolerance. Likewise, adipocytes transfected with an inhibitor of miR-146a displayed a decrease in insulin-stimulated glucose uptake, while transfecting miR-146a mimics caused the opposite effect. Natriuretic peptide receptor 3 (NPR3) was identified as a direct target gene of miR-146a in adipocytes and CRISPR/Cas9-mediated knockout of NPR3 increased insulin-stimulated glucose uptake and enhanced de novo lipogenesis. In summary, miR-146a regulates systemic and adipocyte insulin sensitivity via downregulation of NPR3.

MicroRNAs (−146a, −21 and −34a) are diagnostic and prognostic biomarkers for diabetic retinopathy

Background

Diabetic retinopathy (DR) is implicated in blindness of diabetic patients. Early diagnosis of DR is very essential to ensure good prognosis. The role of microRNAs (miRs) as biomarker diagnostic tools in DR is not fully investigated. The present study aimed to find the relation between serum relative expression of microRNAs (miR-146a, miR-21 and miR-34a) and severity of DR and to what extent their expression pattern can be used as either diagnostic or prognostic.

Methods

Eighty type 2 diabetic patients were classified according to severity of DR into normal, mild, moderate, severe non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). Serum relative expressions of miRNAs were evaluated by qPCR and statistically analysed in each stage using Analysis of Variance (ANOVA) followed by Tuckey-Kramer post-test.

Results

Serum relative expressions of miR-146a and miR-21 were increased with increased severity of DR. miR-34a decreased with the severity of DR. The expression pattern in each group in relation to normal fundus group could be diagnostic and prognostic where miR-146a was only increased in mild group and continued with the severity. In moderate group miR-21 start to increase along with slight decrease in miR-34a. In severe NPDR group along with highly increased levels of both miR-146a and miR-21, a marked decrease in miR-34a. In PDR group miR-34a was almost diminished along with very high levels of both miR-146a and miR-21.

Conclusions

miRs (−146a,-21 and-34a) are promising biomarkers in DR and can help to avoid disease progression.

Global transcriptomic changes occur in aged mouse podocytes

Glomerular podocytes undergo structural and functional changes with advanced age, that increase susceptibility of aging kidneys to worse outcomes following superimposed glomerular diseases. To delineate transcriptional changes in podocytes in aged mice, RNA-seq was performed on isolated populations of reporter-labeled (tdTomato) podocytes from multiple young (two to three months) and advanced aged mice (22 to 24 months, equivalent to 70 plus year old humans). Of the 2,494 differentially expressed genes, 1,219 were higher and 1,275 were lower in aged podocytes. Pathway enrichment showed that major biological processes increased in aged podocytes included immune responses, non-coding RNA metabolism, gene silencing and MAP kinase signaling. Conversely, aged podocytes showed downregulation of developmental, morphogenesis and metabolic processes. Canonical podocyte marker gene expression decreased in aged podocytes, with increases in apoptotic and senescence genes providing a mechanism for the progressive loss of podocytes seen with aging. In addition, we revealed aberrations in the podocyte autocrine signaling network, identified the top transcription factors perturbed in aged podocytes, and uncovered candidate gene modulations that might promote healthy aging in podocytes. The transcriptional signature of aging is distinct from other kidney diseases. Thus, our study provides insights into biomarker discovery and molecular targeting of the aging process itself within podocytes.

MicroRNAs in Podocyte Injury in Diabetic Nephropathy

Diabetic nephropathy is one of the major complications of diabetes mellitus and is the leading cause of end-stage renal disease worldwide. Podocyte injury contributes to the development of diabetic nephropathy. However, the molecules that regulate podocyte injury in diabetic nephropathy have not been fully clarified. MicroRNAs (miRNAs) are small non-coding RNAs that can inhibit the translation of target messenger RNAs. Previous reports have described alteration of the expression levels of many miRNAs in cultured podocyte cells stimulated with a high glucose concentration and podocytes in rodent models of diabetic nephropathy. The associations between podocyte injury and miRNA expression levels in blood, urine, and kidney in patients with diabetic nephropathy have also been reported. Moreover, modulation of the expression of several miRNAs has been shown to have protective effects against podocyte injury in diabetic nephropathy in cultured podocyte cells in vitro and in rodent models of diabetic nephropathy in vivo. Therefore, this review focuses on miRNAs in podocyte injury in diabetic nephropathy, with regard to their potential as biomarkers and miRNA modulation as a therapeutic option.

Urinary exosomal miR-146a as a marker of albuminuria, activity changes and disease flares in lupus nephritis

BACKGROUND

Urinary exosomes, especially microRNAs (miRNAs) packaged within, are ideal sources of renal damage markers. We investigated the association between exosomal miR-146a, (anti-inflammatory regulator) and disease activity, proteinuria and systemic lupus erythematosus (SLE) flares over a 36-month follow-up period.

METHODS

We isolated urinary exosomes from 41 SLE patients, 27 with lupus nephritis (LN) and 20 healthy controls, and exosomal miR-146a, quantified by the real-time quantitative polymerase chain reaction (RT-qPCR), was correlated with histological features in 13 renal biopsies. We also analysed the association between the exosomal miR-146a and TRAF6 axis.

RESULTS

Exosomal miR-146a showed an inverse association with circulating C3 and C4 complement components, proteinuria, and with histological features such as chronicity index. This marker was able to identify LN with an AUC of 0.82 (p = 0.001). Basal exosomal miR-146a was associated with disease activity and proteinuria changes and was an independent marker of 36-month follow-up flares (OR 7.08, p = 0.02). Pathway analysis identified IRAK1 and TRAF6 as miR-146a target genes. Finally, in vitro experiments suggested that miR-146a exerts a protective effect through negative regulation of inflammation by suppressing IRAK1 and TRAF6.

CONCLUSIONS

Urinary exosomal miR-146a levels are correlated with lupus activity, proteinuria and histological features, discriminating patients with LN and being a good baseline marker of SLE flares. We have identified a relevant biological miR-146a-TRAF6 axis association in LN renal fibrosis progression.

Human urine-derived stem cells protect against renal ischemia/reperfusion injury in a rat model via exosomal miR-146a-5p which targets IRAK1

Rationale: Ischemia/reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) that is associated with high morbidity and mortality, and for which specific treatments are lacking. In this study, we investigated the protective effect of human urine-derived stem cells (USCs) and their exosomes against IRI-induced AKI to explore the potential of these cells as a new therapeutic strategy.

Methods: USCs were derived from fresh human urine. Cell surface marker expression was analyzed by flow cytometry to determine the characteristics of the stem cells. Adult male Sprague-Dawley rats were used to generate a lethal renal IRI model. One dose of USCs (2×10⁶ cells/ml) or exosomes (20 µg/1 ml) in the experimental groups or saline (1 ml) in the control group was administered intravenously immediately after blood reperfusion. Blood was drawn every other day for measurement of serum creatinine (sCr) and blood urea nitrogen (BUN) levels. The kidneys were harvested for RNA and protein extraction to examine the levels of apoptosis and tubule injury. In vitro, the hypoxia-reoxygenation (H/R) model in human kidney cortex/proximal tubule cells (HK2) was used to analyze the protective ability of USC-derived exosomes (USC-Exo). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR), western blotting, superoxide dismutase activity, and malonaldehyde content analyses were used to evaluate oxidative stress in HK2 cells treated with USC-Exo after H/R. Exosomal microRNA sequencing techniques and bioinformatics analysis were used to search for enriched miRNAs in the exosomes and interacting genes. The interaction between miRNAs and the 3' untranslated region of the target gene was detected using a dual luciferase reporting system. The miRNA mimic and inhibitor were used to regulate the miRNA level in HK2 cells.

Results: Treatment with USCs led to reductions in the levels of sCr, BUN, and renal tubular cell apoptosis; inhibited the infiltration of inflammatory cells; and protected renal function in the rat IRI model. Additionally, USC-derived exosomes protected against IRI-induced renal damage. miR-146a-5p was the most abundant miRNA in exosomes obtained from the conditioned medium (CM) of USCs. miR-146a-5p targeted and degraded the 3'UTR of interleukin-1 receptor-associated kinase 1 (IRAK1) mRNA, subsequently inhibited the activation of nuclear factor (NF)-κB signaling, and protected HK2 cells from H/R injury. USC transplantation also upregulated miR-146a-5p expression, downregulated IRAK1 expression and inhibited nuclear translocation of NF-κB p65 in the kidney of the rat IRI model.

Conclusions: According to our experimental results, USCs could protect against renal IRI via exosomal miR-146a-5p, which could target the 3'UTR of IRAK1 and subsequently inhibit the activation of NF-κB signaling and infiltration of inflammatory cells to protect renal function. As a novel cell source, USCs represent a promising non-invasive approach for the treatment of IRI.

Amphiregulin Aggravates Glomerulonephritis via Recruitment and Activation of Myeloid Cells

BACKGROUND

Recent studies have identified the EGF receptor (EGFR) ligand amphiregulin (AREG) as an important mediator of inflammatory diseases. Both pro- and anti-inflammatory functions have been described, but the role of AREG in GN remains unknown.

METHODS

The nephrotoxic nephritis model of GN was studied in AREG^-/- mice after bone marrow transplantation, and in mice with myeloid cell-specific EGFR deficiency. Therapeutic utility of AREG neutralization was assessed. Furthermore, AREG's effects on renal cells and monocytes/macrophages (M/M) were analyzed. Finally, we evaluated AREG expression in human renal biopsies.

RESULTS

Renal AREG mRNA was strongly upregulated in murine GN. Renal resident cells were the most functionally relevant source of AREG. Importantly, the observation that knockout mice showed significant amelioration of disease indicates that AREG is pathogenic in GN. AREG enhanced myeloid cell responses via inducing chemokine and colony stimulating factor 2 (CSF2) expression in kidney resident cells. Furthermore, AREG directly skewed M/M to a proinflammatory M1 phenotype and protected them from apoptosis. Consequently, anti-AREG antibody treatment dose-dependently ameliorated GN. Notably, selective abrogation of EGFR signaling in myeloid cells was sufficient to protect against nephritis. Finally, strong upregulation of AREG expression was also detected in kidneys of patients with two forms of crescentic GN.

CONCLUSIONS

AREG is a proinflammatory mediator of GN via (1) enhancing renal pathogenic myeloid cell infiltration and (2) direct effects on M/M polarization, proliferation, and cytokine secretion. The AREG/EGFR axis is a potential therapeutic target for acute GN.

The Role of Chemokines and Chemokine Receptors in Diabetic Nephropathy

Kidney function decline is one of the complications of diabetes mellitus and may be indicated as diabetic nephropathy (DN). DN is a chronic inflammatory disease featuring proteinuria and a decreasing glomerular filtration rate. Despite several therapeutic options being currently available, DN is still the major cause of end-stage renal disease. Accordingly, widespread innovation is needed to improve outcomes in patients with DN. Chemokines and their receptors are critically involved in the inflammatory progression in the development of DN. Although recent studies have shown multiple pathways related to the chemokine system, the specific and direct effects of chemokines and their receptors remain unclear. In this review, we provide an overview of the potential role and mechanism of chemokine systems in DN proposed in recent years. Chemokine system-related mechanisms may provide potential therapeutic targets in DN.

Up-regulation of miR-139-5p protects diabetic mice from liver tissue damage and oxidative stress through inhibiting Notch signaling pathway

The occurrence and development of diabetes seriously threaten the health of patients. Therefore, the mechanism exploration of diabetes is of great significance for more effective control of this disease. In this study, we aimed to investigate the regulatory mechanism of miR-139-5p and Notch signaling pathway on liver damage and oxidative stress in diabetic mice. The mouse model of diabetes was established, and the mice were divided into normal group, model group, negative control (NC) group, miR-139-5p mimic group, miR-139-5p inhibitor group, DAPT group, and miR-139-5p inhibitor + DAPT group. The mRNA expressions of miR-139-5p, Notch1, Jagged1, and NICD1, and the protein expressions of Notch1, Jagged1, and NICD1 were detected. In addition, HepG2 cells were cultured for high glucose induction, and cell cycle distribution and apoptosis were detected by flow cytometry. The results showed that the body weights of mice in the model, NC, miR-139-5p mimic, miR-139-5p inhibitor, DAPT, and miR-139-5p inhibitor + DAPT groups were all lower than that in the normal group. Co-localization of miR-139-5p and Notch1 was observed in the fluorescence in situ hybridization assay, and miR-139-5p was found to negatively regulate Notch1. Furthermore, reduced blood glucose level and inhibited liver oxidative stress were observed in mice with miR-139-5p overexpression or DAPT treatment. DAPT treatment reversed the increase of blood glucose level and oxidative stress injury caused by miR-139-5p silencing. In conclusion, up-regulation of miR-139-5p expression can protect liver tissue from oxidative stress injury in diabetic mice, and its mechanism may be related to the inhibition of Notch signaling pathway.