MicroRNA-21 Silencing in Diabetic Nephropathy: Insights on Therapeutic Strategies

Mechanism of LncRNA-MiRNA in Renal Intrinsic Cells of Diabetic Kidney Disease and Potential Therapeutic Direction

The occurrence of diabetic kidney disease (DKD), a critical microvascular issue in diabetes, is progressively on the rise. In recent years, long noncoding RNAs (lncRNAs) have garnered considerable attention as a novel and critical layer of biological regulation. Our knowledge regarding the roles and underlying mechanisms of lncRNAs in various diseases, including DKD, continues to evolve. Similarly, microRNAs (miRNAs), which are small noncoding RNAs, have been recognized as crucial contributors to cellular processes and disease pathogenesis. Emerging studies have highlighted the complex interactions between lncRNAs and miRNAs, particularly in the context of DKD, underscoring their importance in complex human diseases. Renal intrinsic cell damage is an important cause of inducing DKD. Persistent high glucose stimulation leads to remodeling of renal intrinsic cells and a cascade of pathological changes. This article aims to review recent literature on the lncRNAs-mediated regulation of miRNAs affecting renal intrinsic cells in DKD and to propose novel molecular-level therapeutic strategies for DKD. Through in-depth investigation of this dynamic molecular interaction, we can gain a profound understanding of the potential mechanisms underlying diabetic nephropathy, potentially identifying new targets for therapeutic intervention and paving the way for personalized and effective treatments.

Therapeutic potential of SMAD7 targeting miRNA in the pathogenesis of diabetic nephropathy

Diabetic nephropathy (DN) is a common complication of diabetes and a leading cause of end-stage renal disease, characterized by progressive kidney fibrosis and inflammation. The transforming growth factor-beta (TGF-β) signaling pathway plays a crucial role in the pathogenesis of diabetes nephropathy, and SMAD7 is a key negative regulator of this pathway. Recent studies have highlighted the involvement of miRNA in the progression of DN. Computational analysis identified 11 potential miRNAs such as miR-424, miR-195, miR-216a, miR-503, miR-15a-5p, miR-15b-5p, miR-665, miR-520h, miR16-5p, miR-21 and miR-32-5p which are predicted to target 3'UTR of SMAD7 mRNA. This review aims to explore the role of these miRNAs in the progression of DN. Notably, these miRNAs have shown therapeutic potential in mitigating fibrosis and inflammation by modulating SMAD7 expression in DN. Future directions can be to investigate the mechanistic pathways through which these miRNAs exert their effects, as well as optimizing delivery systems for effective clinical application. Targeting miRNAs that modulate SMAD7 expression represents a promising strategy for developing specific and effective therapies for diabetic nephropathy.

Yiqi Yangyin Huazhuo Tongluo Formula alleviates diabetic podocyte injury by regulating miR-21a-5p/FoxO1/PINK1-mediated mitochondrial autophagy

OBJECTIVES

To investigate the protective effect of Yiqi Yangyin Huazhuo Tongluo Formula (YYHT) against high glucose-induced injury in mouse renal podocytes (MPC5 cells) and the possible mechanism.

METHODS

Adult Wistar rats were treated with 19, 38, and 76 g/kg YYHT or saline via gavage for 7 days to prepare YYHT-medicated or blank sera for treatment of MPC5 cells cultured in high glucose (30 mmol/L) prior to transfection with a miR-21a-5p inhibitor or a miR-21a-5p mimic. The changes in miR-21a-5p expressions and the mRNA levels of FoxO1, PINK1, and Parkin in the treated cells were detected with qRT-PCR, and the protein levels of nephrin, podocin, FoxO1, PINK1, and Parkin were detected with Western blotting. Autophagic activity in the cells were evaluated with MDC staining. The effect of miR-21a-5p mimic on FoxO1 transcription and the binding of miR-21a-5p to FoxO1 were examined with luciferase reporter gene assay and radioimmunoprecipitation assay.

RESULTS

MPC5 cells exposed to high glucose showed significantly increased miR-21a-5p expression, lowered expressions of FoxO1, PINK1, and Parkin1 mRNAs, and reduced levels of FoxO1, PINK1, parkin, nephrin, and podocin proteins and autophagic activity. Treatment of the exposed cells with YYHT-medicated sera and miR-21a-5p inhibitor both significantly enhanced the protein expressions of nephrin and podocin, inhibited the expression of miR-21a-5p, increased the mRNA and protein expressions of FoxO1, PINK1 and Parkin, and upregulated autophagic activity of the cells. Transfection with miR-21a-5p mimic effectively inhibited the transcription of FoxO1 and promoted the binding of miR-21a-5p to FoxO1 in MPC5 cells, and these effects were obviously attenuated by treatment with YYHT-medicated sera.

CONCLUSIONS

YYHT-medicated sera alleviate high glucose-induced injury in MPC5 cells by regulating miR-21a-5p/FoxO1/PINK1-mediated mitochondrial autophagy.

Novel Micro-Ribonucleic Acid Biomarkers for Early Detection of Type 2 Diabetes Mellitus and Associated Complications-A Literature Review

Type 2 diabetes mellitus (T2DM) is one of the most widespread chronic diseases globally, with its prevalence expected to rise significantly in the years ahead. Previous studies on risk stratification for T2DM identify certain biomarkers, including glycated hemoglobin (HbA1c), oral glucose tolerance testing (OGTT), fructosamine, and glycated albumin, as key indicators for predicting the onset and progression of T2DM. However, these traditional markers have been shown to lack sensitivity and specificity and their results are difficult to analyze due to non-standardized interpretation criteria, posing significant challenges to an accurate and definitive diagnosis. The strict measures of these traditional markers may not catch gradual increases in blood sugar levels during the early stages of diabetes evolution, as these might still fall within acceptable glycemic parameters. Recent advancements in research have suggested novel micro ribonucleic acid (miRNA) as circulatory molecules that can facilitate the early detection of prediabetic conditions in high-risk groups and potentially enable prevention of the progression to T2DM. This capability makes them a very powerful tool for potentially improving population health, enhancing outcomes for many patients, and reducing the overall burden of T2DM. These promising biomarkers are small, noncoding RNA involved in the regulation of many cellular functions that have a hand in the metabolic activities of cells, making them a very useful and relevant biomarker to explore for the diagnosis and risk stratification of T2DM. This review analyzes the current literature, outlining the occurrence of miRNAs in prediabetic and diabetic individuals and their implications in predicting dysglycemic disorders.

Enrichment of RedoxifibromiR miR-21-5p in Plasma Exosomes of Hypertensive Patients with Renal Injury

Several microRNAs (miRNAs) emerged as powerful regulators of fibrotic processes, "fibromiRs", and can also influence the expression of genes responsible for the generation of reactive oxygen species, "redoximiRs". We aimed to investigate whether plasma exosomes from hypertensive and diabetes patients are enriched in fibromiRs and redoximiRs using deep sequencing technology and their association with relevant signalling pathways implicated in oxidative stress and fibrogenesis by GO terms and KEGG pathways. RNA-Seq analysis from P-EXO identified 31 differentially expressed (DE) miRNAs in patients compared to controls, of which 77% are biofluid specific. The majority of the exosomal DE miRNAs were identified as fibromiRs (55%) or redoximiRs (26%). One of the most representative miRNAs identified was miR-21-5p, of which levels in P-EXO were increased by 3.83-fold change (p < 0.0001) in hypertensive patients with albuminuria and were highly associated (r Spearman = 0.64, p < 0.0001). In addition, P-EXO miR-21-5p had a high accuracy in discriminating renal damage (AUC = 0.82, p < 0.0001). Bioinformatic analysis revealed that miR-21-5p regulates key pathways in the context of organ fibrosis, such as chemokine, Ras, and MAPK signalling. Additionally, in vitro studies showed an increase in P-EXO miR-21-5p levels after TGF-β1 damage and oxidative stress. This novel study found an enrichment of fibromiRs and redoximiRs in P-EXO from hypertensive/diabetic patients with renal dysfunction. miR-21-5p, such as a RedoxifibromiR, has a significant accuracy for discriminating renal damage and is closely related with relevant signalling pathways implicated in fibrogenesis in podocytes.

Decoding Kidney Pathophysiology: Omics-Driven Approaches in Precision Medicine

Chronic kidney disease (CKD) is a major worldwide health concern because of its progressive nature and complex biology. Traditional diagnostic and therapeutic approaches usually fail to account for disease heterogeneity, resulting in low efficacy. Precision medicine offers a novel approach to studying kidney disease by combining omics technologies such as genomics, transcriptomics, proteomics, metabolomics, and epigenomics. By identifying discrete disease subtypes, molecular biomarkers, and therapeutic targets, these technologies pave the way for personalized treatment approaches. Multi-omics integration has enhanced our understanding of CKD by revealing intricate molecular linkages and pathways that contribute to treatment resistance and disease progression. While pharmacogenomics offers insights into expected responses to personalized treatments, single-cell and spatial transcriptomics can be utilized to investigate biological heterogeneity. Despite significant development, challenges persist, including data integration concerns, high costs, and ethical quandaries. Standardized data protocols, collaborative data-sharing frameworks, and advanced computational tools such as machine learning and causal inference models are required to address these challenges. With the advancement of omics technology, nephrology may benefit from improved diagnostic accuracy, risk assessment, and personalized care. By overcoming these barriers, precision medicine has the potential to develop novel techniques for improving patient outcomes in kidney disease treatment.

Novel therapeutic target for diabetic kidney disease through downregulation of miRNA-192-5p and miRNA-21-5p by celastrol: implication of autophagy, oxidative stress, and fibrosis

One of the most common microvascular effects of diabetes mellitus (DM) that may result in end-stage renal failure is diabetic kidney disease (DKD). Current treatments carry a substantial residual risk of disease progression regardless of treatment. By modulating various molecular targets, pentacyclic triterpenoid celastrol has been found to possess curative properties in the treatment of diabetes and other inflammatory diseases. Therefore, the present study investigated whether celastrol has anti-inflammatory, antioxidant, and antifibrotic effects as a natural compound against experimental DKD. Streptozotocin (55 mg/kg) was utilized for inducing DKD in a rat model. Antioxidant enzymes and renal function tests were assessed in serum samples. In kidney homogenate, relative miRNA-192-5p and miRNA-21-5p gene expressions were measured. Furthermore, using real-time PCR to evaluate the gene expressions of nucleus erythroid 2-related factor-2 (Nrf-2), matrix metalloproteinase-2 (MMP-2), proapoptotic caspase-3, antiapoptotic Bcl-2, LC-3, and Beclin-1. Moreover, the transforming growth factor β1 (TGF-β1), LC-3, Bcl-2, caspase-3 and NADPH oxidase 4 (NOX4) renal expressions were assessed semi-quantitatively using immunohistochemistry. Seven weeks of celastrol (1.5 mg/kg/day) treatment significantly ameliorated DKD. Celastrol improves kidney functions. Moreover, celastrol treatment demonstrated potent antioxidant effect. The mechanism of apoptosis resulting from the administration of celastrol included the modulation of Bcl-2 and caspase-3 expression in the kidney. Celasterol administration leads to an increase in LC-3 and Beclin-1 renal expression that resulting in autophagy. Celastrol treatment improved renal fibrosis by decreasing TGF-β1 and MMP-2 renal expression. These antifibrotic effects could be due to their ability to inhibit miRNA-192-5p and miRNA-21-5p expression in renal tissues. Celastrol exerts a renoprotective effect by targeting miRNA-21 and miRNA-192, as well as their downstream pathways, such as autophagy, apoptosis, and fibrosis.

MicroRNA-630: A potential guardian against inflammation in diabetic kidney disease

In this editorial, we comment on the article by Wu et al published "MicroRNA-630 alleviates inflammatory reactions in rats with diabetic kidney disease by targeting toll-like receptor 4". Diabetic kidney disease (DKD) stands as a significant complication occurring from diabetes mellitus, which contributes substantially to the morbidity and mortality rates worldwide. Renal tubular epithelial cell da-mage, often accompanied by inflammatory responses and mesenchymal trans-differentiation, plays a pivotal role in the progression of DKD. Despite extensive research, the intricate molecular mechanisms underlying these processes remain to be determined. Wu et al remarkable work identifies microRNA-630 (miR-630) as an emerging potential regulator of cell migration, apoptosis, and autophagy, prompting investigation into its association with DKD pathogenesis. This study endeavors to elucidate the impact of miR-630 on TEC injury and the inflammatory response in DKD rats. The role of miR-630 in human DKD will be of interest for future studies.

MiRNA-133a-3p Attenuates Renal Tubular Epithelial Cell Injury via Targeting MALM1 and Suppressing the Notch Signaling Pathway in Diabetic Nephropathy

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes characterized by structural and functional changes of kidneys. Human renal tubular epithelial (HK-2) cells are important for kidney recovery post injury and usually used for establishment of DN cell models. The study explored the role of microRNA (miR)-133a-3p in DN cell model and animal model. A cell model for DN was established via high glucose (HG) stimulation to HK-2 cells. Cell viability and apoptotic rate were measured by cell counting kit 8 and flow cytometry. Polymerase chain reaction was performed to quantify levels of miR-133a-3p and targets. Luciferase reporter assay was conducted to verify the binding of miR-133a-3p and MAML1. After establishment of a mouse model of DN, levels of renal function indicators were measured by biochemical analysis. Hematoxylin-eosin and periodic acid-schiff staining of kidney samples were performed to analyze histological changes. Western blotting was conducted to quantify levels of apoptotic markers, MAML1, and factors related to Notch signaling. Results showed that HG induced HK-2 cell apoptosis and the reduction of cell viability. MiR-133a-3p was lowly expressed in HG-stimulated HK-2 cells. Overexpressed miR-133a-3p improved HK-2 cell injury by increasing cell viability and hampering apoptosis under HG condition. In addition, miR-133a-3p directly targets MAML1 3'-untranslated region. MAML1 overexpression countervailed the repressive impact of miR-133a-3p on cell apoptosis in the context of HG. Moreover, miR-133a-3p inhibited the activity of Notch pathway by downregulating MAML1. MiR-133a-3p inhibits DN progression in mice, as evidenced by reduced fasting blood glucose level, improved levels of renal function parameters, and alleviation of kidney atrophy. In conclusion, miR-133a-3p improves HG-induced HK-2 cell injury and inhibits DN progression by targeting MAML1 and inactivating Notch signaling.

2-Dodecyl-6-Methoxycyclohexa-2, 5-Diene-1, 4-Dione isolated from Averrhoa carambola L. root inhibits high glucose-induced EMT in HK-2 cells through targeting the regulation of miR-21-5p/Smad7 signaling pathway

OBJECTIVE

2-Dodecyl-6-Methoxycyclohexa-2, 5-Diene-1, 4-Dione (DMDD) isolated from Averrhoa carambola L. root, has been proven therapeutic effects on diabetic kidney disease (DKD). This research aims to assess DMDD's effects on DKD and to investigate its underlying mechanisms, to establish DMDD as a novel pharmaceutical agent for DKD treatment.

METHODS

The human renal tubular epithelial (HK-2) cells were induced by high glucose (HG) to mimic DKD and followed by DMDD treatment. The cytotoxicity of DMDD was assessed using the Cell Counting Kit-8 (CCK-8) assay. The migratory capacity of HK-2 cells was evaluated through transwell and scratch-wound assays. To investigate the effect of Smad7 and miR-21-5p, lentiviral transfection was employed in HK-2 cells. Additionally, the expression of proteins related to epithelial-mesenchymal transition (EMT) and TGFβ1/Smad2/3 pathway was checked by QRT-PCR, Western blot, and immunofluorescence techniques.

RESULTS

This study has shown that DMDD significantly suppresses cell migration and the expression of Vimentin, α-SMA, TGFβ1, and p-Smad2/3 in HK-2 cells under HG conditions. Concurrently, DMDD enhances the protein expression of E-cadherin and Smad7. Intriguingly, the therapeutic effect of DMDD was abrogated upon Smad7 silencing. Further investigations revealed that DMDD effectively inhibits miR-21-5p expression, which is upregulated by HG. Downregulation of miR-21-5p inhibits the activation of the TGFβ1/Smad2/3 pathway and EMT induced by HG. In contrast, overexpression of miR-21-5p negates DMDD's therapeutic benefits.

CONCLUSION

DMDD mitigates EMT in HG-induced HK-2 cells by modulating the miR-21-5p/Smad7 pathway, thereby inhibiting renal fibrosis in DKD. These findings suggest that DMDD holds promise as a potential therapeutic agent for DKD.