MicroRNAs and adipocytokines: Promising biomarkers for pharmacological targets in diabetes mellitus and its complications

MiR-488-3p facilitates wound healing through CYP1B1-mediated Wnt/β-catenin signaling pathway by targeting MeCP2

INTRODUCTION

Diabetic wounds are difficult to heal, but the pathogenesis is unknown. MicroRNAs (miRNAs) are thought to play important roles in wound healing. The effect of miR-488-3p in wound healing was studied in this article.

MATERIALS AND METHODS

The gene methylation was measured by methylation specific PCR (MSP) assay. A dual-luciferase reporter assay was adopted to analyze the interaction between miR-488-3p and MeCP2.

RESULTS

Cytochrome P450 1B1 (CYP1B1) is a monooxygenase belonging to the cytochrome P450 family that aids in wound healing. Our findings showed that the miR-488-3p and CYP1B1 expression levels were much lower in wound tissues of diabetics with skin defects, but the methyl-CpG-binding protein 2 (MeCP2) level was significantly higher than that in control skin tissues. MiR-488-3p overexpression increased cell proliferation and migration, as well as HUVEC angiogenesis, while inhibiting apoptosis, according to function experiments. In vitro, MeCP2 inhibited wound healing by acting as a target of miR-488-3p. We later discovered that MeCP2 inhibited CYP1B1 expression by enhancing its methylation state. In addition, CYP1B1 knockdown inhibited wound healing. Furthermore, MeCP2 overexpression abolished the promoting effect of miR-488-3p on wound healing. It also turned out that CYP1B1 promoted wound healing by activating the Wnt4/β-catenin pathway. Animal experiments also showed that miR-488-3p overexpression could accelerate wound healing in diabetic male SD rats.

CONCLUSIONS

MiR-488-3p is a potential therapeutic target for diabetic wound healing since it improved wound healing by activating the CYP1B1-mediated Wnt4/-catenin signaling cascade via MeCP2.

Endogenous and microbial biomarkers for periodontitis and type 2 diabetes mellitus

It has been well documented that there is a two-way relationship between diabetes mellitus and periodontitis. Diabetes mellitus represents an established risk factor for chronic periodontitis. Conversely, chronic periodontitis adversely modulates serum glucose levels in diabetic patients. Activated immune and inflammatory responses are noted during diabetes and periodontitis, under the modulation of similar biological mediators. These activated responses result in increased activity of certain immune-inflammatory mediators including adipokines and microRNAs in diabetic patients with periodontal disease. Notably, certain microbes in the oral cavity were identified to be involved in the occurrence of diabetes and periodontitis. In other words, these immune-inflammatory mediators and microbes may potentially serve as biomarkers for risk assessment and therapy selection in diabetes and periodontitis. In this review, we briefly provide an updated overview on different potential biomarkers, providing novel diagnostic and therapeutic insights on periodontal complications and diabetes mellitus.

Innovative Treatment Strategies to Accelerate Wound Healing: Trajectory and Recent Advancements

Wound healing is highly specialized dynamic multiple phase process for the repair of damaged/injured tissues through an intricate mechanism. Any failure in the normal wound healing process results in abnormal scar formation, and chronic state which is more susceptible to infections. Chronic wounds affect patients’ quality of life along with increased morbidity and mortality and are huge financial burden to healthcare systems worldwide, and thus requires specialized biomedical intensive treatment for its management. The clinical assessment and management of chronic wounds remains challenging despite the development of various therapeutic regimens owing to its painstakingly long-term treatment requirement and complex wound healing mechanism. Various conventional approaches such as cell therapy, gene therapy, growth factor delivery, wound dressings, and skin grafts etc., are being utilized for promoting wound healing in different types of wounds. However, all these abovementioned therapies are not satisfactory for all wound types, therefore, there is an urgent demand for the development of competitive therapies. Therefore, there is a pertinent requirement to develop newer and innovative treatment modalities for multipart therapeutic regimens for chronic wounds. Recent developments in advanced wound care technology includes nanotherapeutics, stem cells therapy, bioengineered skin grafts, and 3D bioprinting-based strategies for improving therapeutic outcomes with a focus on skin regeneration with minimal side effects. The main objective of this review is to provide an updated overview of progress in therapeutic options in chronic wounds healing and management over the years using next generation innovative approaches. Herein, we have discussed the skin function and anatomy, wounds and wound healing processes, followed by conventional treatment modalities for wound healing and skin regeneration. Furthermore, various emerging and innovative strategies for promoting quality wound healing such as nanotherapeutics, stem cells therapy, 3D bioprinted skin, extracellular matrix-based approaches, platelet-rich plasma-based approaches, and cold plasma treatment therapy have been discussed with their benefits and shortcomings. Finally, challenges of these innovative strategies are reviewed with a note on future prospects.

Advanced Glycosylation End Products Induced Synaptic Deficits and Cognitive Decline Through ROS-JNK-p53/miR-34c/SYT1 Axis in Diabetic Encephalopathy

Background: miR-34c has been found to be implicated in the pathological process of Alzheimer’s disease, diabetes, and its complications. Objective: To investigate the underlying mechanisms of miR-34c in the pathogenesis of diabetic encephalopathy (DE). Methods: Diabetes mellitus rats were developed by incorporating a high-fat diet and streptozotocin injection. Morris water maze test and novel object recognition test were used to assess the cognitive function of rats. Expression of miR-34c were detected by fluorescence in situ hybridization and qRT-PCR. Immunofluorescence and western blot were used to evaluate synaptotagmin 1 (SYT1) and AdipoR2 or other proteins. Golgi staining was performed to investigate dendritic spine density. Results: The increased miR-34c induced by advanced glycation end-products (AGEs) was mediated by ROS-JNK-p53 pathway, but not ROS-Rb-E2F1 pathway, in hippocampus of DE rats or in HT-22 cells. miR-34c negatively regulated the expression of SYT1, but not AdipoR2, in hippocampal neurons. miR-34c inhibitor rescued the AGE-induced decrease in the density of dendritic spines in primary hippocampal neurons. Administration of AM34c by the intranasal delivery increased the hippocampus levels of SYT1 and ameliorated the cognitive function in DE rats. The serum levels of miR-34c were increased in patients with DE comparing with normal controls. Conclusion: These results demonstrated that AGE-induced oxidative stress mediated increase of miR-34c through ROS-JNK-p53 pathway, resulting in synaptic deficits and cognitive decline by targeting SYT1 in DE, and the miR-34c/SYT1 axis could be considered as a novel therapeutic target for DE patients.

An update on mode of action of metformin in modulation of meta-inflammation and inflammaging

Type 2 diabetes mellitus (T2DM) is the most common chronic metabolic condition. Several genetic and environmental factors are involved in developing T2DM. Aging, inflammation, and obesity are the main contributors to the initiation of T2DM. They cause chronic sterile meta-inflammation and insulin resistance, thereby making a person more susceptible to developing T2DM. Metformin, a natural cationic biguanide, is widely used as the first-line treatment of T2DM. The exact action mechanism behind the glucose-lowering effect of metformin is not clear, but, presumably, metformin utilizes a broad spectrum of molecular mechanisms to control blood glucose including decreasing intestinal glucose absorption, inhibition of the hepatic gluconeogenesis, decreasing insulin resistance, etc. Recent studies have shown that metformin exerts its effects through the inhibition of mitochondrial respiratory chain complex 1 and the AMP-activated protein kinase (AMPK) activation, but it has been identified in the other studies that AMPK is not the sole hub in metformin mode of action or there are other unknown mechanisms which are involved and yet to be explored. Therefore, here, we discuss the updated findings of the mechanism of action of metformin that contributes to the meta-inflammation and inflammaging action. It is proposed that figuring out the precise mechanism of action of metformin could improve its application in the fields of obesity, inflammation, aging, and inflammaging.

Metabolic Dysfunction Biomarkers as Predictors of Early Diabetes

During the pathophysiological course of type 2 diabetes (T2D), several metabolic imbalances occur. There is increasing evidence that metabolic dysfunction far precedes clinical manifestations. Thus, knowing and understanding metabolic imbalances is crucial to unraveling new strategies and molecules (biomarkers) for the early-stage prediction of the disease's non-clinical phase. Lifestyle interventions must be made with considerable involvement of clinicians, and it should be considered that not all patients will respond in the same manner. Individuals with a high risk of diabetic progression will present compensatory metabolic mechanisms, translated into metabolic biomarkers that will therefore show potential predictive value to differentiate between progressors/non-progressors in T2D. Specific novel biomarkers are being proposed to entrap prediabetes and target progressors to achieve better outcomes. This study provides a review of the latest relevant biomarkers in prediabetes. A search for articles published between 2011 and 2021 was conducted; duplicates were removed, and inclusion criteria were applied. From the 29 studies considered, a survey of the most cited (relevant) biomarkers was conducted and further discussed in the two main identified fields: metabolomics, and miRNA studies.

The Pathophysiological Role of CoA

The importance of coenzyme A (CoA) as a carrier of acyl residues in cell metabolism is well understood. Coenzyme A participates in more than 100 different catabolic and anabolic reactions, including those involved in the metabolism of lipids, carbohydrates, proteins, ethanol, bile acids, and xenobiotics. However, much less is known about the importance of the concentration of this cofactor in various cell compartments and the role of altered CoA concentration in various pathologies. Despite continuous research on these issues, the molecular mechanisms in the regulation of the intracellular level of CoA under pathological conditions are still not well understood. This review summarizes the current knowledge of (a) CoA subcellular concentrations; (b) the roles of CoA synthesis and degradation processes; and (c) protein modification by reversible CoA binding to proteins (CoAlation). Particular attention is paid to (a) the roles of changes in the level of CoA under pathological conditions, such as in neurodegenerative diseases, cancer, myopathies, and infectious diseases; and (b) the beneficial effect of CoA and pantethine (which like CoA is finally converted to Pan and cysteamine), used at pharmacological doses for the treatment of hyperlipidemia.

Impact of Cytomegalovirus Disease on New-Onset Type 2 Diabetes Mellitus: Population-Based Matched Case-Control Cohort Study

BACKGROUND

A latent cytomegalovirus (CMV) cause chronic inflammation through undesirable inflation of cell-mediated immune response. CMV immunoglobulin G has been associated with cardiovascular disease and type 1 diabetes mellitus. We evaluated impact of CMV diseases on new-onset type 2 diabetes mellitus (T2DM).

METHODS

From the Korean Health Insurance Review and Assessment Service claim database of entire population with 50 million, we retrieved 576 adult case group with CMV diseases diagnosed with International Statistical Classification of Diseases and Related-Health Problems 10th Revision (ICD-10) B25 code between 2010 and 2014 after exclusion of patients with T2DM to 2006. The 2,880 control patients without T2DM from 2006 to cohort entry point were selected between 2010 and 2014 by age, sex matching with case group. The subjects without new-onset T2DM were followed until 2015. T2DM, hypertension (HTN), dyslipidemia (DYS), and end-stage renal disease (ESRD) were coded as ICD-10.

RESULTS

The frequency of new-onset T2DM in case group was significantly higher than that in control (5.6% vs. 2.2%, P<0.001). The group with T2DM (n=95) had higher incidence of CMV diseases than the group without T2DM (n=3,361) (33.7% vs. 16.2%, P<0.001). In multivariate regression model adjusted by age, sex, lower income, HTN, and DYS, the incidence rate (IR) of T2DM in case group was significantly higher than that in the control group (IR per 1,000, 19.0 vs. 7.3; odds ratio, 2.1; 95% confidence interval, 1.3 to 3.2). The co-existence of HTN, DYS, and ESRD with CMV diseases did not influence the IR of T2DM.

CONCLUSION

CMV diseases increase the patients' risk of developing T2DM.

A novel transthyretin/STAT4/miR-223-3p/FBXW7 signaling pathway affects neovascularization in diabetic retinopathy

MicroRNAs (miRNAs) are small RNAs without protein-coding functions that negatively regulate target genes and play important roles in physiological and pathological processes. The aim of this work was to reveal a novel miRNA/gene pathway in diabetic retinopathy (DR). A microarray was used to screen miRNAs in samples from nondiabetic controls and patients with DR, and miR-223-3p was screened as a potential candidate. Quantitative real-time PCR (qRT-PCR) revealed that the level of miR-223-3p was frequently overexpressed in DR samples and human retinal endothelial cells (hRECs) in hyperglycemia, but it was decreased in hyperglycemia after the addition of transthyretin (TTR). In addition, according to cell proliferation, tube formation, and wound healing assays, the downregulation of miR-223-3p suppressed cell migration and proliferation, whereas miR-223-3p upregulation showed the opposite effects. Furthermore, luciferase assays identified F-box and WD repeat domain-containing 7 (FBXW7) as a target mRNA of miR-223-3p. High glucose conditions facilitated the recruitment of signal transducer and activator of transcription 4 (STAT4) and promoted the transcription of miR-223-3p. In hRECs, in a hyperglycemic environment, TTR inhibited STAT4 expression, downregulated the level of miR-223-3p, and finally promoted FBXW7 expression. This study found a novel mechanism whereby TTR might affect neovascularization through a newly identified STAT4/miR-223-3p/FBXW7 cascade in DR.

The cross-talk between adipokines and miRNAs in health and obesity-mediated diseases

BACKGROUND

Multiple studies have revealed a direct correlation between obesity and the development of multiple comorbidities, including metabolic diseases, cardiovascular disorders, chronic inflammatory disease, and cancers. However, the molecular mechanism underlying the link between obesity and the progression of these diseases is not completely understood. Adipokines are factors that are secreted by adipocytes and play a key role in whole body homeostasis. Collaboratively, miRNAs are suggested to have key functions in the development of obesity and obesity-related disorders. Based on recently emerging evidence, obesity leads to the dysregulation of both adipokines and obesity-related miRNAs. In the present study, we described the correlations between obesity and its related diseases that are mediated by the mutual regulatory effects of adipokines and miRNAs.

METHODS

We reviewed current knowledge of the modulatory effects of adipokines on miRNAs activity and their relevant functions in pathological conditions and vice versa.

RESULTS

Our research reveals the ability of adipokines and miRNAs to control the expression and activity of the other class of molecules, and their effects on obesity-related diseases.

CONCLUSIONS

This study may help researchers develop a roadmap for future investigations and provide opportunities to develop new therapeutic and diagnostic methods for treating obesity-related diseases.

Angiotensin-(1-7), Adipokines and Inflammation

Nowadays the adipose tissue is recognized as one of the most critical endocrine organs releasing many adipokines that regulate metabolism, inflammation and body homeostasis. There are several described adipokines, including the renin-angiotensin system (RAS) components that are especially activated in some diseases with increased production of angiotensin II and several pro-inflammatory hormones. On the other hand, RAS also expresses angiotensin-(1-7), which is now recognized as the main peptide on counteracting Ang II effects. New studies have shown that increased activation of ACE2/Ang-(1-7)/MasR arm can revert and prevent local and systemic dysfunctions improving lipid profile and insulin resistance by modulating insulin actions, and reducing inflammation. In this context, the present review shows the interaction and relevance of Ang-(1-7) effects on regulating adipokines, and as one adipokine itself, modulating body homeostasis, with emphasis on its anti-inflammatory properties, especially in the context of metabolic disorders with focus on obesity and type 2 diabetes mellitus pandemic.

Ellagic acid ameliorates oxidative stress and insulin resistance in high glucose-treated HepG2 cells via miR-223/keap1-Nrf2 pathway

As a promising new target, miR-233 may regulate oxidative stress by targeting keap1-Nrf2 system to affect the pathological process of liver injury in T2DM. Ellagic acid (EA) is versatile for protecting oxidative stress damage and metabolic disorders. In the present study, we investigated the effect of EA on oxidative stress and insulin resistance in high glucose-induced T2DM HepG2 cells and examined the role of miR-223/keap1-Nrf2 pathway in system. HepG2 cells were incubated in 30 mM of glucose, with or without EA (15 and 30 μM) or metformin (Met, 150 μM) for 12 h. Glucose consumption, phosphorylation of IRS1, Akt and ERK under insulin stimulation, ROS and O₂^- production, MDA level, SOD activity and miR-223 expression, as well as protein levels of keap1, Nrf2, HO-1, SOD1 and SOD2 were analyzed. Furthermore, dual luciferase reporter assay, miR-223 mimic and inhibitor were implemented in cellular studies to explore the possible mechanism. EA upregulated glucose consumption, IRS1, Akt and ERK phosphorylation under insulin stimulation, reduced ROS and O₂^- production and MDA level, and increased SOD activity in high glucose-exposed HepG2 cells. In addition, EA elevated miR-223 expression level, downregulated mRNA and protein levels of keap1, and upregulated Nrf2, HO-1, SOD1 and SOD2 protein levels in this cell model. What's more, dual luciferase reporter assay, miR-223 mimic and inhibitor transfection confirmed that EA activated keap1-Nrf2 system via elevating miR-223. The miR-223, a negative regulator of keap1, represents an attractive therapeutic target in hepatic injury in T2DM. EA ameliorates oxidative stress and insulin resistance via miR-223-mediated keap1-Nrf2 activation in high glucose-induced T2DM HepG2 cells.

MicroRNAs and type 2 diabetes mellitus: Molecular mechanisms and the effect of antidiabetic drug treatment

The incidence of type 2 diabetes mellitus (T2DM), the most prevalent metabolic disease, is rapidly growing worldwide. T2DM has several underlying causes involved in its development. In recent decades, there is compelling evidence demonstrating that microRNAs (miRs) are implicated in the pathophysiology of T2DM. miRs are small non-coding RNAs which serve as endogenous gene regulators by binding to specific sequences in RNA and modifying gene expression toward up- or down-regulation. T2DM occurrence and complications may be influenced by increasing or decreasing the activity of some miRs. In the present narrative review, we comment on four molecular pathways/mechanisms that mediate the link between T2DM and different forms of miRs. These mechanisms include involvement of miRs in beta cells development, insulin sensitivity/resistance, insulin production/secretion and insulin signaling. The effects of antidiabetic drugs on miRs are also discussed.

MicroRNA, Proteins, and Metabolites as Novel Biomarkers for Prediabetes, Diabetes, and Related Complications

Type 2 diabetes mellitus (T2DM) is no more a lifestyle disease of developed countries. It has emerged as a major health problem worldwide including developing countries. However, how diabetes could be detected at an early stage (prediabetes) to prevent the progression of disease is still unclear. Currently used biomarkers like glycated hemoglobin and assessment of blood glucose level have their own limitations. These classical markers can be detected when the disease is already established. Prognosis of disease at early stages and prediction of population at a higher risk require identification of specific markers that are sensitive enough to be detected at early stages of disease. Biomarkers which could predict the risk of disease in people will be useful for developing preventive/proactive therapies to those individuals who are at a higher risk of developing the disease. Recent studies suggested that the expression of biomolecules including microRNAs, proteins, and metabolites specifically change during the progression of T2DM and related complications, suggestive of disease pathology. Owing to their omnipresence in body fluids and their association with onset, progression, and pathogenesis of T2DM, these biomolecules can be potential biomarker for prognosis, diagnosis, and management of disease. In this article, we summarize biomolecules that could be potential biomarkers and their signature changes associated with T2DM and related complications during disease pathogenesis.

The clinical potential of adipogenesis and obesity-related microRNAs

Obesity is a growing health problem commonly associated with numerous metabolic disorders including type 2 diabetes, hypertension, cardiovascular disease, and some forms of cancer. The burden of obesity and associated cardiometabolic diseases are believed to arise through complex interplay between genetics and epigenetics predisposition, nutrition, environment, and lifestyle. However, the molecular basis and the repertoire of obesity-affecting factors are still unknown. Emerging evidence is connecting microRNAs (miRNAs) dysregulation with adipogenesis and obesity. Alteration in miRNAs expression could result in changes in the pattern of genes controlling a range of biological processes including inflammation, lipid metabolism, insulin resistance and adipogenesis. Hence, understanding exact roles of miRNAs as well as the degree of their contribution to the regulation of adipogenesis and fat cell development in obesity would provide new therapeutic targets for the development of novel and effective anti-obesity drugs. The objective of the current review is to: (i) discuss some of the latest development on relevant miRNAs dysregulation mainly in human adipogenesis and obesity, (ii) emphasize the role of circulating miRNAs as new promising therapeutics and attractive potential biomarkers for treating obesity and associated risk factor diseases, (iii) describe how dietary factors may influence obesity through modulation of miRNAs expression, (iv) highlight some of the actual limitations to the promise of miRNAs as novel therapeutics as well as to their translation for the benefit of patients, and finally (v) provide recommendations for future research on miRNA-based therapeutics that could lead to a breakthrough in the treatment of obesity and its associated pathologies.