Urinary miR-21 as a potential biomarker of hypertensive kidney injury and fibrosis

Current perspectives and trends of the research on hypertensive nephropathy: a bibliometric analysis from 2000 to 2023

Hypertensive nephropathy continues to be a major cause of end-stage renal disease and poses a significant global health burden. Despite the staggering development of research in hypertensive nephropathy, scientists and clinicians can only seek out useful information through articles and reviews, it remains a hurdle for them to quickly track the trend in this field. This study uses the bibliometric method to identify the evolutionary development and recent hotspots of hypertensive nephropathy. The Web of Science Core Collection database was used to extract publications on hypertensive nephropathy from January 2000 to November 2023. CiteSpace was used to capture the patterns and trends from multi-perspectives, including countries/regions, institutions, keywords, and references. In total, 557 publications on hypertensive nephropathy were eligible for inclusion. China (n = 208, 37.34%) was the most influential contributor among all the countries. Veterans Health Administration (n = 19, 3.41%) was found to be the most productive institution. Keyword bursting till now are renal fibrosis, outcomes, and mechanisms which are predicted to be the potential frontiers and hotspots in the future. The top seven references were listed, and their burst strength was shown. A comprehensive overview of the current status and research frontiers of hypertensive nephropathy has been provided through the bibliometric perspective. Recent advancements and challenges in hypertensive nephropathy have been discussed. These findings can offer informative instructions for researchers and scholars.

Clinical role of serum microRNA-155 in early diagnosis and prognosis of septic patients with acute kidney injury

BACKGROUND AND PURPOSE

Acute kidney injury (AKI) is a common complication in patients with sepsis, and early detection and timely treatment are crucial. This article aims to explore the clinical role of microRNA-155 (miR-155) in early diagnosis and prognosis evaluation of septic patients with acute kidney injury.

METHODS

We collected the blood samples of septic patients and measured the relative expression of serum miR-155 by RT-qPCR, and drew the receiver operating characteristic (ROC) curves to evaluate its early diagnosis for septic AKI.

RESULTS

The relative expression of miR-155 in the septic AKI was significantly higher than that in the septic non-AKI, and increased with the aggravation of renal function damage. The ROC curve of miR-155 for the diagnosis of septic AKI was 1.91 (95% CI: 1.61-2.19). When the optimal cut-off value of miR-155 expression was 2.37, its sensitivity for diagnosing septic AKI was 91.12% (95% CI: 80.41-95.07%), and its specificity was 84.52% (95% CI: 71.74-89.36%). Furthermore, the severity of kidney injury, SOFA score, APACHE II score and miR-155 were the risk factors affecting the prognosis of septic patients with AKI.

CONCLUSION

Serum miR-155 can be used as a novel biomarker for the early diagnosis of septic AKI, and also has important clinical value in the prognosis evaluation of septic patients with AKI.

Potential of Modulating Aldosterone Signaling and Mineralocorticoid Receptor with microRNAs to Attenuate Diabetic Kidney Disease

Diabetic Kidney Disease (DKD) is a significant complication of diabetes and primary cause of end-stage renal disease globally. The exact mechanisms underlying DKD remain poorly understood, but multiple factors, including the renin-angiotensin-aldosterone system (RAAS), play a key role in its progression. Aldosterone, a mineralocorticoid steroid hormone, is one of the key components of RAAS and a potential mediator of renal damage and inflammation in DKD. miRNAs, small noncoding RNA molecules, have attracted interest due to their regulatory roles in numerous biological processes. These processes include aldosterone signaling and mineralocorticoid receptor (MR) expression. Numerous miRNAs have been recognized as crucial regulators of aldosterone signaling and MR expression. These miRNAs affect different aspects of the RAAS pathway and subsequent molecular processes, which impact sodium balance, ion transport, and fibrosis regulation. This review investigates the regulatory roles of particular miRNAs in modulating aldosterone signaling and MR activation, focusing on their impact on kidney injury, inflammation, and fibrosis. Understanding the complex interaction between miRNAs and the RAAS could lead to a new strategy to target aldosterone signaling and MR activation using miRNAs. This highlights the potential of miRNA-based interventions for DKD, with the aim of enhancing kidney outcomes in individuals with diabetes.

Prolonged Antibiotic Use in a Preclinical Model of Gulf War Chronic Multisymptom-Illness Causes Renal Fibrosis-like Pathology via Increased micro-RNA 21-Induced PTEN Inhibition That Is Correlated with Low Host Lachnospiraceae Abundance

Gulf War (GW) veterans show gastrointestinal disturbances and gut dysbiosis. Prolonged antibiotic treatments commonly employed in veterans, especially the use of fluoroquinolones and aminoglycosides, have also been associated with dysbiosis. This study investigates the effect of prolonged antibiotic exposure on risks of adverse renal pathology and its association with gut bacterial species abundance in underlying GWI and aims to uncover the molecular mechanisms leading to possible renal dysfunction with aging. Using a GWI mouse model, administration of a prolonged antibiotic regimen involving neomycin and enrofloxacin treatment for 5 months showed an exacerbated renal inflammation with increased NF-κB activation and pro-inflammatory cytokines levels. Involvement of the high mobility group 1 (HMGB1)-mediated receptor for advanced glycation end products (RAGE) activation triggered an inflammatory phenotype and increased transforming growth factor-β (TGF-β) production. Mechanistically, TGF-β- induced microRNA-21 upregulation in the renal tissue leads to decreased phosphatase and tensin homolog (PTEN) expression. The above event led to the activation of protein kinase-B (AKT) signaling, resulting in increased fibronectin production and fibrosis-like pathology. Importantly, the increased miR-21 was associated with low levels of Lachnospiraceae in the host gut which is also a key to heightened HMGB1-mediated inflammation. Overall, though correlative, the study highlights the complex interplay between GWI, host gut dysbiosis, prolonged antibiotics usage, and renal pathology via miR-21/PTEN/AKT signaling.

Biomarkers of the End-Stage Renal Disease Progression: Beyond the GFR

Chronic kidney disease can progress to the end-stage renal disease (ESRD) characterized by a high risk of morbidity and mortality. ESRD requires immediate therapy or even dialysis or kidney transplantation, therefore, its timely diagnostics is critical for many patients. ESRD is associated with pathological changes, such as inflammation, fibrosis, endocrine disorders, and epigenetic changes in various cells, which could serve as ESRD markers. The review summarizes information on conventional and new ESRD biomarkers that can be assessed in kidney tissue, blood, and urine. Some biomarkers are specific to a particular pathology, while others are more universal. Here, we suggest several universal inflammatory, fibrotic, hormonal, and epigenetic markers indicative of severe deterioration of renal function and ESRD progression for improvement of ESRD diagnostics.

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

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

High Expression Levels of miR-21-5p in Younger Hospitalized COVID-19 Patients Are Associated with Mortality and Critical Disease

In COVID-19, critical disease and invasive mechanical ventilation (IMV) increase the risk of death, mainly in patients over 60 years of age.

OBJECTIVES

To find the relationship between miR-21-5p and miR-146a-5p in terms of the severity, IMV, and mortality in hospitalized COVID-19 patients younger than 55 years of age.

METHODS

The patients were stratified according to disease severity using the IDSA/WHO criteria for severe and critical COVID-19 and subclassified into critical non-survivors and critical survivors.

RESULTS

Ninety-seven severe/critical COVID-19 patients were included; 81.3% of the deceased were male and 18.8% were female. Higher expression miR-21-5p levels were associated as follows: severe vs. critical disease (p = 0.007, FC = 0.498), PaO₂/FiO₂ index, mild vs. severe (p = 0.027, FC = 0.558), and survivors vs. non-survivors (p = 0.03, FC = 0.463). Moreover, we identified correlations with clinical variables: CRP (rho = -0.54, p < 0.001), D-dimer (rho = -0.47, p < 0.05), related to damage in the kidney (rho = 0.60, p < 0.001), liver (rho = 0.41, p < 0.05), and lung (rho = 0.54, p < 0.001). Finally, miR-21-5p thresholds were calculated according to severity (8.191), IMV (8.191), and mortality (8.237); these values increased the risk of developing a critical disease (OR = 4.19), the need for IMV (OR = 5.63), and death (OR = 6.00).

CONCLUSION

Increased expression levels of miR-21-5p are related to worse outcome of COVID-19 in younger hospitalized patients.

Deciphering the role of lipoproteins and lipid metabolic alterations in ageing and ageing-associated renal fibrosis

Fibrosis is the ultimate pathological feature of many chronic diseases, and ageing a major risk factor for fibrotic diseases. Current therapies are limited to those that reduce the rate of functional decline in patients with mild to moderate disease, but few interventions are available to specifically target the pathogenesis of fibrosis. In this context, new treatments that can significantly improve survival time and quality of life for these patients are urgently needed. In this review, we outline both the synthesis and metabolism of lipids and lipoproteins associated with ageing-associated renal fibrosis and the prominent contribution of lipids and lipidomics in the discovery of biomarkers that can be used for the prevention, diagnosis, and treatment of renal ageing and fibrosis. Next, we describe the effect of dyslipidaemia on ageing-related renal fibrosis and the pathophysiological changes in the kidney caused by dyslipidaemia. We then summarize the enzymes, transporters, transcription factors, and RNAs that contribute to dysregulated lipid metabolism in renal fibrosis and discuss their role in renal fibrosis in detail. We conclude by discussing the progress in research on small molecule therapeutic agents that prevent and treat ageing and ageing-associated renal fibrosis by modulating lipid metabolism. A growing number of studies suggest that restoring aberrant lipid metabolism may be a novel and promising therapeutic strategy to combat ageing and ageing-associated renal fibrosis.

Clinical, biochemical, and miRNA profile of subjects with positive screening of primary aldosteronism and nonclassic apparent mineralocorticoid excess

Primary aldosteronism (PA) and nonclassic apparent mineralocorticoid excess (NCAME) have been recognized as endocrine-related conditions having a broad clinical-biochemical spectrum, spanning from normotension to severe arterial hypertension (AHT). However, the coexistence of both phenotypes have not been reported to date.

AIM

To identify and characterize clinical and biochemical parameters of subjects with both PA and NCAME conditions (NCAME&PA) and study the miRNA cargo in their urinary extracellular vesicles as potential biomarkers for this novel condition.

METHODS

We performed a cross-sectional study of 206 Chilean adult subjects from a primary care cohort. We measured blood pressure (BP), cortisol (F), cortisone (E), aldosterone, plasma renin activity (PRA), microalbuminuria (MAC), plasma NGAL, MMP9, fractional-potassium-excretion (FEK). Subjects were classified as NCAME&PA, PA, NCAME, essential hypertensives (EH), or healthy controls (CTL). EV-miRNAs were quantified by Taqman-qPCR.

RESULTS

We found that 30.6% subjects had an abnormal endocrine phenotype: NCAME&PA (6.8%), PA (11.2%) or NCAME (12.6%), and the prevalence of AHT was 92.9%, 82.6%, and 65%, respectively. NCAME&PA subjects had both lower cortisone (p < 0.05) and lower PRA (p < 0.0001), higher FEK (p = 0.02) and higher MAC (p = 0.01) than EH or CTL. NCAME&PA subjects had also higher NGAL levels than CTL and PA (p < 0.05). Exosome miR-192, miR-133a and miR-21 expression decreased with phenotype severity and correlated with BP and PRA (p < 0.05).

CONCLUSION

We identified adult subjects with a combined condition of NCAME and PA associated with higher BP, increased renal and endothelial damage markers than control and EH. Additionally, we observed a differential expression of a specific miRNAs, suggesting a potential role of these miRNAs associated to this novel combined phenotype.

Target amplification-free detection of urinary microRNA for diabetic nephropathy diagnosis with electrocatalytic reaction

Diabetic nephropathy (DN) is a serious diabetic complication, usually developed from type II diabetes mellitus (T2DM) and known as type II DN (T2DN). New emerging biomarkers for T2DN are microRNAs (miRNAs) which have been studied for the noninvasive early-stage detection of the disease. In this work, a nucleic acid amplification-free miRNA-124 sensor based on target-induced strand displacement on magnetic beads, and by using methylene blue-loaded silica particles as a label was developed. Measurement methods can be either visual observation, spectrophotometry, or electrochemistry. After incubation and separation of the magnetic particles, a blue-violet solution (564 nm) appeared, depending on the concentration of miRNA displaced. For electrochemical detection, methylene blue on the silica served as a redox mediator for the coupled reaction with ferricyanide in the solution phase. At the electrode surface, ferricyanide was re-reduced to ferrocyanide, and was thus available for further reaction with methylene blue, forming an amplification cycle. After optimization, the total assay time was 60 min, and limits of detection were 1 pM, 6 fM, and 0.65 fM, by the naked eye, spectrophotometry and electrochemistry, respectively. The miRNAs in 42 suspected urine samples from patients suffering from either diabetic nephropathy, diabetes mellitus, or chronic kidney disease were validated by comparing with the droplet digital polymerase chain reaction (ddPCR).

Hypotensive effect of captopril on deoxycorticosterone acetate-salt-induced hypertensive rat is associated with gut microbiota alteration

The role of the gut microbiota in various metabolic diseases has been widely studied. This study aims to test the hypothesis that gut microbiota dysbiosis is associated with DOCA-salt-induced hypertension, while captopril, an antihypertensive drug, is able to rebalance the gut microbiota alterations caused by hypertension. Treatment with captopril resulted in an approximate 32 mmHg reduction in systolic blood pressure (162.57 vs. 194.61 mmHg) in DOCA-salt-induced hypertensive rats, although it was significantly higher than that in SHAM rats (136.10 mmHg). Moreover, the nitric oxide (NO) level was significantly increased (20.60 vs. 6.42 µM) while the angiotensin II (Ang II) content (42.40 vs. 59.47 pg/ml) was attenuated nonsignificantly by captopril treatment in comparison to those of DOCA-salt-induced hypertensive rats. The introduction of captopril significantly decreased the levels of tumor necrosis factor-α (TNF-ɑ) and interleukin-6 (IL-6). Hypertrophy and fibrosis in kidneys and hearts were also significantly attenuated by captopril. Furthermore, gut microbiota dysbiosis was observed in DOCA-salt-induced hypertensive rats. The abundances of several phyla and genera, including Proteobacteria, Cyanobacteria, Escherichia-Shigella, Eubacterium nodatum and Ruminococcus, were higher in DOCA-salt-induced hypertensive rats than in SHAM rats, while these changes were reversed by captopril treatment. Of particular interest, the genera Bifidobacterium and Akkermansia, reported as beneficial bacteria in the gut, were abundant in only hypertensive rats treated with captopril. These results provide evidence that captopril has the potential to rebalance the dysbiotic gut microbiota of DOCA-salt-induced hypertensive rats, suggesting that the alteration of the gut flora by captopril may contribute to the hypotensive effect of this drug.

Primary Aldosteronism, Aldosterone, and Extracellular Vesicles

Primary aldosteronism (PA) is an endocrine related condition leading to arterial hypertension due to inappropriately high and unregulated aldosterone concentration. Recently, a broad spectrum of PA has been recognized, which brings new challenges associated with early identification of this condition that affect renal epithelial and extrarenal tissues. Reports have shown the potential role of extracellular vesicles (EVs) and EV cargo as novel and complementary biomarkers in diagnosis and prognosis of PA. In vivo and in vitro studies have identified specific EV surface antigens, EV-proteins, and EV microRNAs that can be useful to develop novel diagnostic algorithms to detect, confirm, or follow up the PA. Moreover, the study of EVs in the field of PA provides further insight in the pathophysiological mechanism of the PA disease.

Tribulus terrestris L. protects glomerular endothelial cells via the miR155-H2AC6 interaction network in hypertensive renal injury

Background

Hypertensive renal injury is one of the most lethal complications of hypertension. At present, renin-angiotensin-aldosterone system (RAAS) blockers are considered the best drugs for the treatment of renal injury in hypertension because of their nephroprotective effect of reducing proteinuria, but there are no specific drugs for this purpose, however, clinical trials proved that Chinese medicine has a protective effect on target organs in the treatment of hypertension. Tribulus terrestris L. (TrT), a traditional Chinese medicine (TCM), has potential applications due to its reno-protective and immunomodulatory effects.

Methods

We investigated the underlying reno-protective mechanism of TrT on Angiotensin II (AngII)-induced hypertensive renal injury in glomerular endothelial cells by integrating the differential expression profiles of micro RNA (miRNA) and messenger RNA (mRNA) to construct a miRNA-mRNA interaction network associated with hypertensive kidney injury, followed by quantitative real-time polymerase chain reaction (qRT-PCR) for validation.

Results

Seventy-six differentially expressed mRNAs (DEmRNAs) and 1 differentially expressed miRNAs (DEmiRNAs) were identified in the control group and the AngII-induced hypertensive renal injury group, respectively. 110 DEmRNAs and 27 DEmiRNAs were identified in the TrT treatment group and the AngII-induced group, respectively. The core component of the miRNA-mRNA network was miR-155-5p. Our study showed that miR-155-5p expression levels were more decreased in the AngII-induced hypertensive renal injury group than the control group. TrT treatment also significantly upregulated miR-155-5p. Additionally, we found that miR-155-5p expression levels were negatively correlated with H2A clustered histone 6 (H2AC6).

Conclusions

The results of this study indicate that TrT has a reno-protective effect on AngII-induced hypertensive renal injury by miR-155-5p, which negatively regulates the expression of H2AC6. Our findings offer a new therapeutic strategy and have identified an effective candidate target for the treatment of hypertensive renal injury in clinical settings.

Serum Alpha-1-Acid Glycoprotein-1 and Urinary Extracellular Vesicle miR-21-5p as Potential Biomarkers of Primary Aldosteronism

Primary aldosteronism (PA) is the most common cause of secondary hypertension and reaches a prevalence of 6-10%. PA is an endocrine disorder, currently identified as a broad-spectrum phenotype, spanning from normotension to hypertension. In this regard, several studies have made advances in the identification of mediators and novel biomarkers of PA as specific proteins, miRNAs, and lately, extracellular vesicles (EVs) and their cargo.

Aim

To evaluate lipocalins LCN2 and AGP1, and specific urinary EV miR-21-5p and Let-7i-5p as novel biomarkers for PA.

Subjects and Methods

A cross-sectional study was performed in 41 adult subjects classified as normotensive controls (CTL), essential hypertensives (EH), and primary aldosteronism (PA) subjects, who were similar in gender, age, and BMI. Systolic (SBP) and diastolic (DBP) blood pressure, aldosterone, plasma renin activity (PRA), and aldosterone to renin ratio (ARR) were determined. Inflammatory parameters were defined as hs-C-reactive protein (hs-CRP), PAI-1, MMP9, IL6, LCN2, LCN2-MMP9, and AGP1. We isolated urinary EVs (uEVs) and measured two miRNA cargo miR-21-5p and Let-7i-5p by Taqman-qPCR. Statistical analyses as group comparisons were performed by Kruskall-Wallis, and discriminatory analyses by ROC curves were performed with SPSS v21 and Graphpad-Prism v9.

Results

PA and EH subjects have significantly higher SBP and DBP (p <0.05) than the control group. PA subjects have similar hs-CRP, PAI-1, IL-6, MMP9, LCN2, and LCN2-MMP9 but have higher levels of AGP1 (p <0.05) than the CTL&EH group. The concentration and size of uEVs and miRNA Let-7i-5p did not show any difference between groups. In PA, we found significantly lower levels of miR-21-5p than controls (p <0.05). AGP1 was associated with aldosterone, PRA, and ARR. ROC curves detected AUC for AGP1 of 0.90 (IC 95 [0.79 - 1.00], p <0.001), and combination of AGP1 and EV-miR-21-5p showed an AUC of 0.94 (IC 95 [0.85 - 1.00], p<0.001) to discriminate the PA condition from EH and controls.

Conclusion

Serum AGP1 protein was found to be increased, and miR-21-5p in uEVs was decreased in subjects classified as PA. Association of AGP1 with aldosterone, renin activity, and ARR, besides the high discriminatory capacity of AGP1 and uEV-miR-21-5p to identify the PA condition, place both as potential biomarkers of PA.

MicroRNA 132-3p Is Upregulated in Laron Syndrome Patients and Controls Longevity Gene Expression

The growth hormone (GH)–insulin-like growth factor-1 (IGF1) endocrine axis is a central player in normal growth and metabolism as well as in a number of pathologies, including cancer. The GH–IGF1 hormonal system, in addition, has emerged as a major determinant of lifespan and healthspan. Laron syndrome (LS), the best characterized entity under the spectrum of the congenital IGF1 deficiencies, results from mutation of the GH receptor (GHR) gene, leading to dwarfism, obesity and other defects. Consistent with the key role of IGF1 in cellular proliferation, epidemiological studies have shown that LS patients are protected from cancer development. While reduced expression of components of the GH-IGF1 axis is associated with enhanced longevity in animal models, it is still unknown whether LS is associated with an increased lifespan. MicroRNAs (miRs) are endogenous short non-coding RNAs that regulate the expression of complementary mRNAs. While a number of miRs involved in the regulation of IGF components have been identified, no previous studies have investigated the differential expression of miRs in congenital IGF1 deficiencies. The present study was aimed at identifying miRs that are differentially expressed in LS and that might account for the phenotypic features of LS patients, including longevity. Our genomic analyses provide evidence that miR-132-3p was highly expressed in LS. In addition, we identified SIRT1, a member of the sirtuin family of histone deacetylases, as a target for negative regulation by miR-132-3p. The data was consistent with the notion that low concentrations of IGF1 in LS lead to elevated miR-132-3p levels, with ensuing reduction in SIRT1 gene expression. The impact of the IGF1-miR-132-3p-SIRT1 loop on aging merits further investigation.

Association between circulating microRNAs and changes in kidney function: A five-year prospective study among Japanese adults without CKD

BACKGROUND

Although a number of microRNAs (miRNA) reflecting kidney function has been identified, prospective studies are now urgently needed to determine a clinical utility of these miRNAs among general populations. The purpose of this study was to examine the associations between serum miRNAs and kidney function in a population-based study.

METHODS

We conducted a five-year prospective study (2012-2017) of 169 individuals without chronic kidney disease (CKD) at the baseline survey (mean age, 62.5; 96 women). The real-time qPCR was used to measure serum levels of five previously reported miRNAs. Participants with eGFR < 60 mL/min/1.73 m² were defined as having CKD. Changes in eGFR were defined as eGFR₂₀₁₇ - eGFR₂₀₁₂.

RESULTS

After adjusting for covariates including baseline eGFR, lower serum levels (1st tertile) of miR-126 were associated with a greater decline of eGFR (β [SE] = -3.18 [1.50]) and a higher odds ratio (OR) of CKD onset over five years (OR [95% CI] = 3.85 [1.01-16.8]), compared with the 3rd tertile.

CONCLUSIONS

We found baseline serum miR-126 levels were associated with changes in eGFR and new CKD cases in a five-year prospective study. This result suggests that miR-126 may be a potential biomarker of CKD even among general populations.

Methodological considerations for measuring biofluid-based microRNA biomarkers

MicroRNAs (miRNAs) are small non-coding RNA that regulate the expression of messenger RNA and are implicated in almost all cellular processes. Importantly, miRNAs can be released extracellularly and are stable in these matrices where they may serve as indicators of organ or cell-specific toxicity, disease, and biological status. There has thus been great enthusiasm for developing miRNAs as biomarkers of adverse outcomes for scientific, regulatory, and clinical purposes. Despite advances in measurement capabilities for miRNAs, miRNAs are still not routinely employed as noninvasive biomarkers. This is in part due to the lack of standard approaches for sample preparation and miRNA measurement and uncertainty in their biological interpretation. Members of the microRNA Biomarkers Workgroup within the Health and Environmental Sciences Institute's (HESI) Committee on Emerging Systems Toxicology for the Assessment of Risk (eSTAR) are a consortium of private- and public-sector scientists dedicated to developing miRNAs as applied biomarkers. Here, we explore major impediments to routine acceptance and use of miRNA biomarkers and case examples of successes and deficiencies in development. Finally, we provide insight on miRNA measurement, collection, and analysis tools to provide solid footing for addressing knowledge gaps toward routine biomarker use.

Evaluation of Biological Mechanisms of Eucommiae Folium in Hypertensive Kidney Injury by Integration of Untargeted Metabolomics and Network Pharmacology

Hypertensive kidney injury (Hki) is one of the most common complications of hypertension. Early prevention and treatment of renal injury in patients with hypertension is great significance. The study, which used an integrated ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS) analysis, network pharmacology approach, and plasma metabolomics, aimed to discover the active ingredients and therapeutic mechanisms of Eucommiae folium (Ef) in treating Hki. The chemical components of Ef were analyzed by UPLC-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS), and the "compound-target-disease" network was constructed by screening the closely related drug targets from the drug-target database, then the signaling pathways related to Hki were analyzed. Finally, the enzyme-linked immunosorbent assay (ELISA) and real-time quantitative reverse-transcription polymerase chain reaction were used to test and verify the key targets in the common pathways of metabolomics and network pharmacology. The results indicated that Eucommiae folium might play an excellent role in treating Hki, likely through regulating the vascular endothelial growth factor signaling pathway, hypoxia inducible factor 1 (HIF-1) signaling pathway, and glycerophospholipid metabolism pathway, which were validated by increasing levels of nitric oxide, endothelial nitric oxide synthase and reducing levels of endothelin 1, angiotensin II, renin, cyclic guanosine monophosphate, blood urea nitrogen, and serum creatinine, as well as the reduced gene expression of Ache, Ddah2, Egfr, Lcat, Pla2g2a, Stat3 and Vegfa. The study systematically explored the protective mechanisms of Ef against Hki and also provided the practical treatment strategies of Hki from the Chinese herb.

TimiRGeN: R/Bioconductor package for time series microRNA-mRNA integration and analysis

Motivation

The analysis of longitudinal datasets and construction of gene regulatory networks (GRNs) provide a valuable means to disentangle the complexity of microRNA (miRNA)–mRNA interactions. However, there are no computational tools that can integrate, conduct functional analysis and generate detailed networks from longitudinal miRNA–mRNA datasets.

Results

We present TimiRGeN, an R package that uses time point-based differential expression results to identify miRNA–mRNA interactions influencing signaling pathways of interest. miRNA–mRNA interactions can be visualized in R or exported to PathVisio or Cytoscape. The output can be used for hypothesis generation and directing in vitro or further in silico work such as GRN construction.

Availability and implementation

TimiRGeN is available for download on Bioconductor (https://bioconductor.org/packages/TimiRGeN) and requires R v4.0.2 or newer and BiocManager v3.12 or newer.

Supplementary information

Supplementary data are available at Bioinformatics online.

Therapeutic effects of micro-RNAs in preclinical studies of acute kidney injury: a systematic review and meta-analysis

AKI has a high mortality rate, may lead to chronic kidney disease, and effective therapies are lacking. Micro-RNAs (miRNAs) regulate biologic processes by potently inhibiting protein expression, and pre-clinical studies have explored their roles in AKI. We conducted a systematic review and meta-analysis of miRNAs as therapeutics in pre-clinical AKI. Study screening, data extraction, and quality assessments were performed by 2 independent reviewers. Seventy studies involving 42 miRNA species were included in the analysis. All studies demonstrated significant effects of the miRNA intervention on kidney function and/or histology, with most implicating apoptosis and phosphatase and tensin homolog (PTEN) signaling. Fourteen studies (20.0%) examined the effect of miRNA-21 in AKI, and meta-analysis demonstrated significant increases in serum creatinine and kidney injury scores with miR-21 antagonism and pre-conditioning. No studies reported on adverse effects of miRNA therapy. Limitations also included lack of model diversity (100% rodents, 61.4% ischemia-reperfusion injury), and predominance of male sex (78.6%). Most studies had an unclear risk of bias, and the majority of miRNA-21 studies were conducted by a single team of investigators. In summary, several miRNAs target kidney function and apoptosis in pre-clinical AKI models, with data suggesting that miRNA-21 may mediate protection and kidney repair.Systematic review registration ID: CRD42019128854.

MicroRNA 21 and microRNA 155 levels in resistant hypertension, and their relationships with aldosterone

Aim

MicroRNAs (miRNAs) are non-coding RNA molecules that serve as regulators following gene expression transcription. While studies have investigated the role of miRNAs in the pathogenesis of essential hypertension (HT), very few have considered their place in the pathogenesis of resistant hypertension (RH). The purpose of this study was to investigate levels of miRNA 21 and miRNA 155 in RH and their relationships with aldosterone.

Method

Thirty-two normotensive patients, 30 newly diagnosed HT patients, and 20 RH patients were included in the study. Patients’ demographic data were recorded, and office blood pressure measurement and 24-h ambulatory blood pressure monitoring (24-h ABPM) were performed. Blood specimens were collected for miRNA 21, miRNA 155 and aldosterone measurement. MiRNA 21 and miRNA 155 levels in the control and patient groups and their relations with other demographic and biochemical parameters were then subjected to analysis.

Results

No difference was determined in miRNA 155 levels between the groups, but miRNA 21 and aldosterone levels were significantly higher in the RH group (p < 0.001 and <0.05, respectively). At correlation analysis, miRNA 21 exhibited positive correlation with aldosterone, age, office SBP, 24-h ABPM all-day SBP. A 9.6 copy/uL level for miRNA 21 predicted presence or absence of RH with 95% sensitivity and 71% specificity (AUC:0.823, 95% CI (0.72–0.92).

Conclusion

The study results revealed significantly higher miRNA 21 and aldosterone in RH patients than in healthy individuals and newly diagnosed hypertensives.

Dietary supplementation of Huangshan Maofeng green tea preventing hypertension of older C57BL/6 mice induced by desoxycorticosterone acetate and salt

Senile hypertension affects the life quality of aged population. Dietary intervention plays a pivotal role in the prevention of hypertension. There are few reports concerning the effects and mechanisms of green tea supplementation preventing age related hypertension. The current study investigated the effect and mechanism of dietary supplement of Huangshan Maofeng green tea (HSMF) on prevention of hypertension induced by deoxycorticosterone acetate (DOCA) and salt in old C57BL/6 mice. Our results showed that HSMF dose-dependently prevented the increase of systolic blood pressure and diastolic blood pressure induced by DOCA plus salt (DS) at 51-week-old mice. And HSMF significantly reduced the agonists' stimulated contraction of mesenteric arteries isolated from the old mice. The expression of vasoconstrictor genes and inflammatory cytokines in aorta were suppressed observably by HSMF supplementation compared with DS group. The protein expression of PKCα in the aorta was dose-dependently decreased by HSMF compared to DS group. The phosphorylation level of MYPT1, CPI-17and MLC20 was also restrained by HSMF in the aorta. Furthermore, HSMF protected kidney by maintaining integrity of glomeruli and tubules and remarkably decreased the NGAL level in plasma. HSMF also suppressed the kidney inflammation by decreasing inflammatory cytokines expression and the macrophage infiltration. Our results proved that dietary supplement of HSMF remarkably improved the vascular functions and protected kidney injury, and thus prevented hypertension induced by DS in older C57BL/6 mice. Our data indicated that the dietary supplement of HSMF may potentially be used as a food additive for preventing hypertension for aged people.

MicroRNA 21 Emerging Role in Diabetic Complications: A Critical Update

BACKGROUND

Diabetes Mellitus is a multifactorial disease encompassing various pathogenic pathways. To avoid morbidity and mortality related to diabetic complications, early detection of disease complications as well as targeted therapeutic strategies are essential.

INTRODUCTION

MicroRNAs (miRs) are short non-coding RNA molecules that regulate eukaryotic posttranscriptional gene expression. MicroRNA-21 has diverse gene regulatory functions and plays a significant role in various complications of Type 2 diabetes mellitus (T2DM).

METHODS

The study included electronic database searches on Pubmed, Embase, and Web of Science with the search items MicroRNA21 and each of the diabetic complications. The search was carried out up to November, 2019.

RESULTS

MicroRNA-21 modulates diabetic cardiomyopathy by affecting vascular smooth muscle cell proliferation and apoptosis, cardiac cell growth and death, and cardiac fibroblast functions. At the renal tubules, miR-21 can regulate the mesangial expansion, interstitial fibrosis, macrophage infiltration, podocyte loss, albuminuria and fibrotic and inflammatory gene expression related to diabetic nephropathy. Overexpression of miR-21 has been seen to play a pivotal role in the pathogenesis of diabetic retinopathy by contributing to diabetes-induced endothelial dysfunction as well as low-grade inflammation.

CONCLUSION

Considering the raised levels of miR-21 in various diabetic complications, it may prove to be a candidate biomarker for diabetic complications. Further, miR-21 antagonists have shown great potential in the treatment of diabetic cardiomyopathy, diabetic nephropathy, diabetic retinopathy, and diabetic neuropathy related complications in the future. The current review is the first of its kind encompassing the roles miR-21 plays in various diabetic complications, with a critical discussion of its future potential role as a biomarker and therapeutic target.

Kidney microRNA-21 Expression and Kidney Function in IgA Nephropathy

Rationale & Objective

Previous studies have suggested that microRNA-21 (miR-21) plays an important role in kidney fibrosis. We examined the relationship between intrarenal miR-21 level and rate of kidney function loss in immunoglobulin A nephropathy (IgAN).

Study Design

Prospective cohort study.

Setting & Participants

40 patients with IgAN and 10 with hypertensive nephrosclerosis as controls.

Predictors

miR-21 levels in kidney biopsy specimen and urinary sediment, quantified as ratio to the housekeeping gene.

Outcomes

Kidney event–free survival and rate of kidney function decline.

Analytic Approach

Time-to-event and correlation analysis.

Results

The IgAN group had significantly higher intrarenal miR-21 expression compared with the hypertensive nephrosclerosis group (1.71 [IQR, 0.99-2.77] vs 0.31 [IQR, 0.25-1.32]; P < 0.0001), but urinary miR-21 levels were similar. Intrarenal miR-21 expression had significant but modest correlation with severity of glomerulosclerosis (r = 0.293; P = 0.05) and tubulointerstitial fibrosis (r = 0.341; P = 0.03). Patients with high intrarenal miR-21 expression had significantly higher risk for developing kidney end points compared with those with low expression (log-rank test, P = 0.017). Univariate Cox analysis showed that intrarenal miR-21 expression significantly predicted the development of kidney end points (unadjusted HR, 1.586; 95% CI, 1.179-2.134; P = 0.002). However, the result was just short of statistical significance after adjusting for the severity of histologic damage (P = 0.06). There was also a significant correlation between intrarenal miR-21 expression and the slope of kidney function decline by univariate analysis (r = −0.399; P = 0.02).

Limitations

Small sample size; uncertain cellular origin of miR-21.

Conclusions

We found that intrarenal miR-21 expression is increased in patients with IgAN, modestly correlated with the severity of histologic damage, and predictive of subsequent kidney function loss.

Serum Lysyl Oxidase Is a Potential Diagnostic Biomarker for Kidney Fibrosis

BACKGROUND

Kidney fibrosis is the ultimate consequence of advanced stages of chronic kidney disease (CKD); however, there are currently no reliable biomarkers or noninvasive diagnostic tests available for the detection of kidney fibrosis. Lysyl oxidase (LOX) promotes collagen cross-linking, and serum LOX levels have been shown to be elevated in patients with fibrosis of the heart, lungs, and liver. However, serum LOX levels have not been reported in patients with kidney fibrosis. We explored whether serum LOX levels are associated with kidney fibrosis.

METHOD

Overall, 202 patients with kidney disease underwent renal biopsy, scoring of kidney fibrosis, and determination of the area of kidney fibrosis. LOX levels were measured in serum and in kidney tissues. We analyzed the association of circulating LOX and tissue LOX levels with the scores and areas of kidney fibrosis. LOX expression was also investigated with in vitro and in vivo kidney fibrosis models.

RESULTS

Serum LOX levels were higher in patients with kidney fibrosis than in those without kidney fibrosis (p < 0.001) and higher in patients with moderate-severe kidney fibrosis than in patients with mild kidney fibrosis (p < 0.001). Both serum LOX and renal tissue LOX levels correlated with the area of kidney fibrosis (r = 0.748, p < 0.001; r = 0.899, p < 0.001, respectively). Receiver operating characteristic curve analysis of serum LOX levels showed an area under the curve of 0.80 (95% CI: 0.74-0.86). The optimal serum LOX level cutoff point was 253.34 pg/mL for the prediction of kidney fibrosis and 306.56 pg/mL for the prediction of moderate-severe kidney fibrosis. LOX expression levels were significantly upregulated (2.3-2.6 and 6-fold, respectively) in in vitro and in vivo interstitial fibrosis models.

CONCLUSIONS

Both serum LOX and tissue LOX levels correlated with the presence and degree of kidney fibrosis in patients with CKD. These results suggest that serum LOX levels could potentially serve as a noninvasive diagnostic biomarker for kidney fibrosis and may further potentially serve as a stratified biomarker for the identification of mild and moderate-severe kidney fibrosis.

Urinary versus serum microRNAs in human oxalic acid poisoning: Contrasting signals and performance

MicroRNAs are key regulators of the normal kidney function and development, and altered in acute kidney injury (AKI). However, there is a lack of studies comparing serum and urine miRNA expression in toxic AKI in humans. We aimed to compare the global signature of urinary and serum microRNAs, with and without kidney injury, after human oxalic acid poisoning. We profiled urinary microRNAs in patients who ingested oxalic acid and developed no injury (No AKI n = 3), moderate injury (AKIN2 n = 3) or severe injury (AKIN3 n = 3) and healthy controls (n = 3). We validated a signature of 30 urinary microRNAs identified in the discovery profiling, in a second cohort of individuals exposed to oxalic acid (No AKI n = 15, AKIN2 n=11 & AKIN3 n= 18) and healthy controls (n=-27) and we compared the results with previously published serum data. Global profiling in toxic AKI patients showed a higher expression of urinary microRNAs and lower expression of serum microRNAs. Most urine microRNA in the validation cohort were significantly upregulated (25/30, fold change >2.8 and p < 0.05) in AKIN2/3 patients compared to No AKI. Four urinary microRNAs (miR-191, miR-19b, miR-20a and miR-30b) had good diagnostic performance (AUC greater than 0.8) to predict AKIN2/3 between 4-8 hours post ingestion. Poisoning irrespective of AKI led to significantly lower expression of many microRNAs in serum but relatively few changes in urinary miRNA expression. In conclusion, urinary microRNA signature provides a stronger measure of AKI in oxalic acid poisoning compared to serum microRNA. Kidney injury has the greatest impact on urinary microRNA, while poisoning itself was better reflected in serum miRNA. Plasma and urinary microRNAs signatures provide complementary information in toxic kidney injury.

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.

MicroRNA-451 as an Early Predictor of Chronic Kidney Disease in Diabetic Nephropathy

Background

Diabetes mellitus is the leading cause of end-stage renal disease worldwide. Microalbuminuria is the cornerstone for the diagnosis of diabetic nephropathy. However, it is an inadequate marker for early diagnosis. MicroRNAs are not only new and promising markers for early diagnosis but also, but they may also play a role in the prevention of disease progression.

Methods

This study included ninety patients with type 2 DM in addition to 30 control subjects. MicroRNA-451 expression in blood and plasma using real-time PCR was evaluated in addition to the classic diabetic nephropathy markers (serum creatinine, urinary albumin, and eGFR).

Results

There was a significant difference between the studied groups versus control regarding serum creatinine, eGFR, urinary, and plasma microRNA-451 with p=0.0001. Patients with eGFR 60 ml/min/1.73 m² showed a significantly higher plasma microRNA-451 (29.6 ± 1.6) and significantly lower urinary microRNA-451 (21 ± 0.9) in comparison to patients with eGFR >60 ml/min/1.73 m² and p=0.0001. eGFR showed a positive correlation with urinary microRNA-451 and negative correlation with both plasma microRNA-451 and urinary albumin. Both plasma and urinary microRNA-451 are highly sensitive and specific markers for chronicity in diabetic nephropathy patients with sensitivity of 90.9% and 95.5% and specificity of 67.6% and 95.6%, respectively.

Conclusion

MicroRNA-451 is a promising early biomarker for chronic kidney disease in diabetic nephropathy with high sensitivity and specificity.

Are women more susceptible to renal dysfunction than men?

Is there any difference in sensitivity to kidney function between men and women? Paterson et al. have focused on sex differences in chronic kidney disease. Surprisingly, their experimental results show that only one microRNA, miR-146b-5p, affected the susceptibility of renocardiac pathology. They generated miR-146b knockout rats and found that miR-146b^-/- females developed exacerbated renal hypertrophy and fibrosis and had less cardiac remodeling. Although miR-146b-5p has been reported to be upregulated in various types of cancers, this article reveals the novel role of miR-146b in the kidney.

MiRNAs as potential biomarker of kidney diseases: A review

MicroRNAs (miRNAs) are 22 nucleotides short, non-coding and tissue-specific single-stranded RNA which modulates target gene expression. Presently, shreds of evidence confirmed that miRNAs play a key role in kidney pathophysiology. The objectives of the present review are to summarize new research data towards the latest developments in the potential use of miRNAs as a diagnostic biomarker for kidney diseases. This holistic information will update the existing knowledge of kidney disease biomarkers. "miRNA profile for Diabetic Kidney disease, Acute kidney injury, Renal fibrosis, hemodialysis, transplants, FSGS, IgAN, etc." are the search keywords which have been used in this review. The search outcome gave an exciting insightful perception of miRNAs competence as a biomarker. Also it is observed that various samples as plasma, urine and biopsies were used for profiling the miRNA expression. The miRNAs were not only used for diagnostic biomarkers but also for therapeutic targets. Each kidney disease showed different miRNAs expression profile and few miRNAs quite common with some kidney diseases. miRNAs are simple and efficient diagnostic biomarkers for kidney diseases.

Diagnostic and Therapeutic Potential of microRNAs in Acute Kidney Injury

During hospital stay, about 20% of adult patients experience an episode of acute kidney injury (AKI), which is characterized by a rapid decrease in kidney function. Diagnostic tools regarding early diagnosis of kidney dysfunction prior to AKI and markers of renal recovery are not available. Additionally, there is no therapeutic option for the treatment of AKI. Thus, better and more specific diagnostic and therapeutic options are urgently needed in daily clinical practice. NoncodingRNAs (ncRNAs) have come into focus of research in the context of AKI in the last decade. The best characterized group of ncRNAs are microRNAs (miRNAs). An increasing body of literature has shown that miRNAs are involved in the pathogenesis of AKI and that they are promising future tools in the diagnosis and therapy of AKI. However, there are obstacles to be overcome before miRNAs can be transferred to patient care. This review will give an overview of our current knowledge of miRNA involvement in the context of AKI while critically evaluating their diagnostic and therapeutic potential.

miR-451 Loaded Exosomes Are Released by the Renal Cells in Response to Injury and Associated With Reduced Kidney Function in Human

Micro-RNAs (miRs) encapsulated inside urinary exosomes (uEs) have the potential as early biomarkers. Previously, we reported that a rise in uE miR-451 predicted albuminuria in diabetic rats; however, whether the rise was protective or detrimental, and occurred in response to injury or general hyperglycemia, was unknown. To address this, we studied both human and rat models of renal disease. In humans, uE miR-451 was approximately twofold higher in subjects with early-stage chronic kidney disease (CKD; serum creatinine < 2.0 mg/dl; n = 28), as compared to age-matched healthy controls (n = 23), and had a significant negative correlation with estimated glomerular filtration rate (eGFR) (r² = −0.10, p = 0.01). Subgroup analysis of CKD subjects showed that those without diabetes had slightly (∼30%) but significantly higher uE miR-451 as compared to those with diabetes, with no differences in albumin excretion, eGFR, serum sodium, and potassium. Using human proximal tubule (hPT) cells, we found that locked nucleic acid (LNA) inhibition of miR-451 resulted in a significant increase in the messenger RNA (mRNA) expression of kidney-injury-associated miR-451 targets, e.g., CAB39, TBX1, and YWHAZ, as compared to treatment with a control LNA. Moreover, hPT cells and their secreted exosomes showed an increase in miR-451 in response to mechanical injury but not high glucose (20 versus 5 mM). For further proof of concept, in diabetic rats, we showed that atorvastatin (AT), a treatment proven to attenuate renal injury without affecting systemic glucose levels, reduced uE miR-451 with the concomitant restoration of renal miR-451. These data elucidate the stimuli for renal miR-451 expression and exosomal release and support its role as a therapeutic target and early biomarker for renal injury in humans.

Diagnostic, Prognostic, and Therapeutic Value of Non-Coding RNA Expression Profiles in Renal Transplantation

End-stage renal disease is a public health problem responsible for millions of deaths worldwide each year. Although transplantation is the preferred treatment for patients in need of renal replacement therapy, long-term allograft survival remains challenging. Advances in high-throughput methods for large-scale molecular data generation and computational analysis are promising to overcome the current limitations posed by conventional diagnostic and disease classifications post-transplantation. Non-coding RNAs (ncRNAs) are RNA molecules that, despite lacking protein-coding potential, are essential in the regulation of epigenetic, transcriptional, and post-translational mechanisms involved in both health and disease. A large body of evidence suggests that ncRNAs can act as biomarkers of renal injury and graft loss after transplantation. Hence, the focus of this review is to discuss the existing molecular signatures of non-coding transcripts and their value to improve diagnosis, predict the risk of rejection, and guide therapeutic choices post-transplantation.

MicroRNA‑21 contributes to renal cell carcinoma cell invasiveness and angiogenesis via the PDCD4/c‑Jun (AP‑1) signalling pathway

Accumulating evidence has demonstrated that microRNAs are associated with malignant biological behaviour, including tumorigenesis, cancer progression and metastasis via the regulation of target gene expression. Our previous study demonstrated that programmed cell death protein 4 (PDCD4), which is a tumour suppressor gene, is a target of microRNA‑21 (miR‑21), which affects the proliferation and transformation capabilities of renal cell carcinoma (RCC) cells. However, the role of miR‑21 in the molecular mechanism underlying the migration, invasion and angiogenesis of RCC remains poorly understood. The effects of miR‑21 on the invasion, migration and angiogenesis of RCC cells was determined through meta‑analysis and regulation of miR‑21 expression in vitro. After searching several databases, 6 articles including a total of 473 patients met the eligibility criteria for this analysis. The combined results of the meta‑analysis revealed that increased miR‑21 expression was significantly associated with adverse prognosis in patients with RCC, with a pooled hazard ratio estimate of 1.740. In in vitro experiments, we demonstrated that a miR‑21 inhibitor decreased the number of migrating and invading A498 and 786‑O RCC cells, along with a decrease in PDCD4, c‑Jun, matrix metalloproteinase (MMP)2 and MMP9 expression. Additionally, inhibition of miR‑21 was revealed to reduce tube formation and tube junctions in the endothelial cell line HMEC‑1 by affecting the expression of angiotensin‑1 and vascular endothelial growth factor A, whereas PDCD4 small interfering RNA exerted opposite effects on the same cells. Overall, these findings, along with evidence‑based molecular biology, demonstrated that miR‑21 expression promoted the migration, invasion and angiogenic abilities of RCC cells by directly targeting the PDCD4/c‑Jun signalling pathway. The results may help elucidate the molecular mechanism underlying the development and progression of RCC and provide a promising target for microRNA‑based therapy.

Bromodomain and Extraterminal Proteins as Novel Epigenetic Targets for Renal Diseases

Epigenetic mechanisms, especially DNA methylation and histone modifications, are dynamic processes that regulate the gene expression transcriptional program in normal and diseased states. The bromodomain and extraterminal (BET) protein family (BRD2, BRD3, BRD4, and BRDT) are epigenetic readers that, via bromodomains, regulate gene transcription by binding to acetylated lysine residues on histones and master transcriptional factors. Experimental data have demonstrated the involvement of some BET proteins in many pathological conditions, including tumor development, infections, autoimmunity, and inflammation. Selective bromodomain inhibitors are epigenetic drugs that block the interaction between BET proteins and acetylated proteins, thus exerting beneficial effects. Recent data have described the beneficial effect of BET inhibition on experimental renal diseases. Emerging evidence underscores the importance of environmental modifications in the origin of pathological features in chronic kidney diseases (CKD). Several cellular processes such as oxidation, metabolic disorders, cytokines, inflammation, or accumulated uremic toxins may induce epigenetic modifications that regulate key processes involved in renal damage and in other pathological conditions observed in CKD patients. Here, we review how targeting bromodomains in BET proteins may regulate essential processes involved in renal diseases and in associated complications found in CKD patients, such as cardiovascular damage, highlighting the potential of epigenetic therapeutic strategies against BET proteins for CKD treatment and associated risks.

Biomarkers of Chronic Renal Tubulointerstitial Injury

Progression of renal parenchyma injury is characterized by increasing interstitial fibrosis and tubular atrophy, irrespective of the cause. Histopathologic assessment of renal tissue obtained by biopsy remains the gold standard for determining the presence and extent of tubulointerstitial scarring. Discovery of robust non-invasive means for capturing a snapshot and for longitudinal monitoring of parenchymal deterioration has been the focus of intense multimodal effort by investigators within the renal community and beyond. Research in this field has included the use of in vitro and in vivo experimental models and has fostered the development and evaluation of tissue and biofluid assays for novel analytes with potential translation to the diagnosis and prognosis of kidney disease. Here, we examine recent advances in the search of "biomarkers" for detection of renal tubulointerstitial scarring and prediction of renal outcome in human renal disease.

Non-Coding RNAs as New Therapeutic Targets in the Context of Renal Fibrosis

Fibrosis, or tissue scarring, is defined as the excessive, persistent and destructive accumulation of extracellular matrix components in response to chronic tissue injury. Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function. Limited therapeutic options are available and the molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the role of non-coding RNAs, and in particular microRNAs (miRNAs), has been described in kidney fibrosis. Seminal studies have highlighted their potential importance as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review will summarize recent scientific advances and will discuss potential clinical applications as well as future research directions.

β-N-Oxalyl-L-α,β-diaminopropionic acid from Panax notoginseng plays a major role in the treatment of type 2 diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the most serious and dangerous chronic complications of diabetes mellitus.Panax notoginseng has been widely used with great efficacy in the long-term treatment of kidney disease. However, the mechanism by which it exerts its effects has not been fully elucidated.

AIM

We sought to identify the major components ofPanax notoginseng that are effective in reducing the symptoms of DN in vitro and in vivo.

METHODS

Inhibition of cell proliferation and collagen secretion were used to screen the ten most highly concentrated components ofPanax notoginseng. The STZ-induced DN rat model on a high-fat-high-glucose diet was used to investigate the renal protective effect of Panax notoginseng and dencichine and their underlying molecular mechanisms.

RESULTS

Among the ten components analysed, dencichine (β-N-oxalyl-L-α,β-diaminopropionic acid) was the most protective against DN. Dencichine andPanax notoginseng attenuated glucose and lipid metabolic disorders in STZ-induced DN rats on a high-fat-high-glucose diet. In the untreated DN rats, we observed albuminuria, renal failure, and pathological changes. However, treatment with dencichine and Panax notoginseng alleviated these symptoms. We also observed that dencichine suppressed the expression of TGF-β1 and Smad2/3, which mediates mesangial cell proliferation and extracellular matrix (ECM) accumulation in the glomerulus, and enhanced the expression of Smad7, the endogenous inhibitor of the TGF-β1/Smad signalling pathway.

CONCLUSION

From these results, we concluded that dencichine is the main compound inPanax notoginseng that is responsible for alleviating renal injury in the experimental DN model. Its mechanism may be related to the reduction of the deposition of ECM in glomeruli and inhibition of the epithelial mesenchymal transformation (EMT) by inhibition of the TGF-β1/Smad signalling pathway.

Associations of Circulating MicroRNAs (miR-17, miR-21, and miR-150) and Chronic Kidney Disease in a Japanese Population

Background

MicroRNAs (miRNAs) play crucial roles in the development of various diseases, including chronic kidney disease (CKD). Although previous studies in clinically severe patients have investigated associations between CKD and miRNAs, with particular attention on renal fibrosis, relationships in a general population have yet to be established. The aim of this study was to examine the relationship between expression level of circulating miRNAs and CKD in a middle-aged Japanese population.

Methods

A final total of 513 individuals (216 men and 297 women) who participated in the health check-up program in 2012 were included in our analysis. Quantitative real-time polymerase chain reaction was used to determine expression levels of 22 miRNAs. Estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine level, sex, and age. Participants with eGFR <60 mL/min/1.73 m² were defined as having CKD.

Results

Three different miRNAs (miR-17, miR-21, and miR-150) showed significant correlations with eGFR after Bonferroni correction and were selected for further analyses. Expression levels of miR-17, miR-21, and miR-150 miRNAs were positively associated with eGFR after adjusting for potential confounders (P = 0.004, 0.002, and 0.004, respectively). Logistic regression analyses showed significantly lower odds ratios for CKD (eGFR <60 mL/min/1.73 m²) in the highest tertile of all three miRNAs (miR-17, miR-21, and miR-150) compared with the lowest tertile (P = 0.003, 0.01, and 0.02, respectively).

Conclusions

We found that three circulating miRNAs were significantly associated with CKD in a general Japanese population, which suggested that these miRNAs may be biomarkers for CKD among general adults.

Comparison of Cardiac miRNA Transcriptomes Induced by Diabetes and Rapamycin Treatment and Identification of a Rapamycin-Associated Cardiac MicroRNA Signature

Rapamycin (Rap), an inhibitor of mTORC1, reduces obesity and improves lifespan in mice. However, hyperglycemia and lipid disorders are adverse side effects in patients receiving Rap treatment. We previously reported that diabetes induces pansuppression of cardiac cytokines in Zucker obese rats (ZO-C). Rap treatment (750 μg/kg/day for 12 weeks) reduced their obesity and cardiac fibrosis significantly; however, it increased their hyperglycemia and did not improve their cardiac diastolic parameters. Moreover, Rap treatment of healthy Zucker lean rats (ZL-C) induced cardiac fibrosis. Rap-induced changes in ZL-C's cardiac cytokine profile shared similarities with that of diabetes-induced ZO-C. Therefore, we hypothesized that the cardiac microRNA transcriptome induced by diabetes and Rap treatment could share similarities. Here, we compared the cardiac miRNA transcriptome of ZL-C to ZO-C, Rap-treated ZL (ZL-Rap), and ZO (ZO-Rap). We report that 80% of diabetes-induced miRNA transcriptome (40 differentially expressed miRNAs by minimum 1.5-fold in ZO-C versus ZL-C; p ≤ 0.05) is similar to 47% of Rap-induced miRNA transcriptome in ZL (68 differentially expressed miRNAs by minimum 1.5-fold in ZL-Rap versus ZL-C; p ≤ 0.05). This remarkable similarity between diabetes-induced and Rap-induced cardiac microRNA transcriptome underscores the role of miRNAs in Rap-induced insulin resistance. We also show that Rap treatment altered the expression of the same 17 miRNAs in ZL and ZO hearts indicating that these 17 miRNAs comprise a unique Rap-induced cardiac miRNA signature. Interestingly, only four miRNAs were significantly differentially expressed between ZO-C and ZO-Rap, indicating that, unlike the nondiabetic heart, Rap did not substantially change the miRNA transcriptome in the diabetic heart. In silico analyses showed that (a) mRNA-miRNA interactions exist between differentially expressed cardiac cytokines and miRNAs, (b) human orthologs of rat miRNAs that are strongly correlated with cardiac fibrosis may modulate profibrotic TGF-β signaling, and (c) changes in miRNA transcriptome caused by diabetes or Rap treatment include cardioprotective miRNAs indicating a concurrent activation of an adaptive mechanism to protect the heart in conditions that exacerbate diabetes.

miR-21 Protects Against Ischemia/Reperfusion-Induced Acute Kidney Injury by Preventing Epithelial Cell Apoptosis and Inhibiting Dendritic Cell Maturation

Renal tubular injury and innate immune responses induced by hypoxia contribute to acute kidney injury. Accumulating evidence suggests that miR-21 overexpression protects against kidney ischemia injury. Additionally, miR-21 emerges as a key inhibitor in dendritic cell maturation. Thus, we hypothesized that miR-21 protects the kidney from IR injury by suppressing epithelial cell damage and inflammatory reaction. In this study, we investigated effects of miR-21 and its signaling pathways (PTEN/AKT/mTOR/HIF, PDCD4/NFκ-B) on kidney ischemia/reperfusion (IR) injury in vitro and in vivo. The results revealed that IR increased miR-21, HIF1α, and 2α expression in vivo and in vitro. MiR-21 interacted with HIF1α and 2α through the PTEN/AKT/mTOR pathway. Moreover, inhibition of miR-21 activated PDCD4/NFκ-B pathways, which are critical for dendritic cell maturation. Renal IR triggers local inflammation by inducing the dendritic cell maturation and promoting the secretion of IL-12, IL-6, and TNF-α cytokines. Knockdown of miR-21 intensified the effect of IR on tubular epithelial cell apoptosis and dendritic cell maturation. Our results suggested that IR-inducible miR-21 protects epithelial cells from IR injury via a feedback interaction with HIF (PTEN/AKT/mTOR/HIF/miR-21) and by inhibiting maturation of DCs through the PDCD4/NF-κB pathway. These findings highlight new therapeutic opportunities in AKI.