Circulating miR-146a, miR-34a and miR-375 in type 2 diabetes patients, pre-diabetic and normal-glycaemic individuals in relation to β-cell function, insulin resistance and metabolic parameters

Visceral Adipocyte-Derived Extracellular Vesicle miR-27a-5p Elicits Glucose Intolerance by Inhibiting Pancreatic β-Cell Insulin Secretion

Pancreatic β-cell dysfunction caused by obesity can be associated with alterations in the levels of miRNAs. However, the role of miRNAs in such processes remains elusive. Here, we show that pancreatic islet miR-27a-5p, which is markedly increased in obese mice and impairs insulin secretion, is mainly delivered by visceral adipocyte-derived extracellular vesicles (EVs). Depleting miR-27a-5p significantly improved insulin secretion and glucose intolerance in db/db mice. Supporting the function of EV miR-27a-5p as a key pathogenic factor, intravenous injection of miR-27a-5p-containing EVs showed their distribution in mouse pancreatic islets. Tracing the injected adeno-associated virus (AAV)-miR-27a-5p (AAV-miR-27a) or AAV-FABP4-miR-27a-5p (AAV-FABP4-miR-27a) in visceral fat resulted in upregulating miR-27a-5p in EVs and serum and elicited mouse pancreatic β-cell dysfunction. Mechanistically, miR-27a-5p directly targeted L-type Ca2+ channel subtype CaV1.2 (Cacna1c) and reduced insulin secretion in β-cells. Overexpressing mouse CaV1.2 largely abolished the insulin secretion injury induced by miR-27a-5p. These findings reveal a causative role of EV miR-27a-5p in visceral adipocyte-mediated pancreatic β-cell dysfunction in obesity-associated type 2 diabetes mellitus.

ARTICLE HIGHLIGHTS

Role of Decreased Expression of miR-155 and miR-146a in Peripheral Blood of Type 2 Diabetes Mellitus Patients with Diabetic Peripheral Neuropathy

Objective

To Study the Correlations of microRNA-155 (miR-155) and microRNA-146a (miR-146a) Expression in Peripheral Blood of Type 2 Diabetes Mellitus (T2DM) Patients with Diabetic Peripheral Neuropathy (DPN), and Explore the Clinical Value of miR-155 and miR-146a in the Diagnosis and Treatment Outcomes of DPN.

Methods

The study included 51 T2DM patients without DPN (T2DM group), 49 T2DM patients with DPN (DPN group), and 50 normal controls (NC group). Quantitative real-time PCR was utilized to determine the expression levels of miR-155 and miR-146a. Clinical features and risk factors for DPN were assessed. Multivariate stepwise logistic regression analysis was conducted to confirm whether the expressions of miR-155 and miR-146a could independently predict the risk of DPN. ROC curve analysis evaluated their diagnostic value.

Results

The T2DM group exhibited significantly lower expression levels of miR-155 and miR-146a compared to the NC group (P < 0.05). Moreover, the DPN group exhibited a significantly decreased expression level of miR-155 and miR-146a compared to the T2DM group (P < 0.01). Multivariate logistic regression analysis indicated that higher levels of miR-155 and miR-146a might serve as protective factors against DPN development. ROC curve analysis revealed that miR-155 (sensitivity 91.8%, specificity 37.3%, AUC 0.641,) and miR-146a (sensitivity 57.1%, specificity 84.3%, AUC 0.722) possess a strong ability to discriminate between T2DM and DPN. Their combined use further enhanced the diagnostic potential of DPN (sensitivity 83.7%, specificity 60.8%, AUC 0.775). A multi-index combination can improve DPN diagnostic efficiency.

Conclusion

The decreased expression of miR-155 and miR-146a in the peripheral blood of T2DM patients is closely related to the occurrence of DPN, highlighting their potential as valuable biomarkers for diagnosing and prognosticating DPN.

Altered expression of miR-375 and miR-541 in type 2 diabetes patients with and without coronary artery disease (CAD): the potential of miR-375 as a CAD biomarker

Background

MicroRNAs (miRNAs, miRs) have been linked to beta-cell pathologies and have also shown potential as biomarkers for cardiovascular disease. This study aimed to evaluate the expression of miR-375 and miR-541 in T2D patients with and without CAD, in order to determine the potential of these miRNAs as biomarkers for assessing CAD risk.

Methods

This study was conducted on 106 patients with T2D who underwent coronary angiographic examination. Reverse transcription was performed using the cDNA synthesis kit. Real-time PCR was performed using the SYBR Green method and specific primers. The ability to predict which person had developed CAD was evaluated by calculating the area under the receiver-operating characteristic (ROC) curve (AUC).

Results

The expression of miR-375 was significantly higher in samples from CAD patients compared to those without CAD (p = 0.009). While the expression of miR-541 was also higher in CAD patients, the difference was not statistically significant. In terms of predicting CAD, miR-375 was found to be a suitable predictor with an AUC of 0.74 (p = 0.01), while miR-541 was not. With a cut-off value of 0.016 for miR-375, the sensitivity was 67% and the specificity was 80%.

Conclusion

Our results indicated that circulating levels of miR-375 and miR-541 were elevated in T2D patients with CAD compared to those without CAD. This suggests that miR-375 could potentially be used as a non-invasive biomarker for the diagnosis of CAD in T2D patients.

SIRT1 and miR-34a-5p Expression in PBMCs as Potential Biomarkers for Patients With Type 2 Diabetes With Cognitive Impairments

CONTEXT

Patients with type 2 diabetes mellitus (T2DM) are at significantly increased risk of Alzheimer disease (AD). However, no biomarkers are available for early identification of patients with T2DM with cognitive impairment (T2DM-CI). Mitochondrial dysfunction is linked to AD. Silent Information Regulator 1 (SIRT1), which is responsible for regulating mitochondrial biogenesis, and its related miRNAs were also altered in AD.

OBJECTIVE

This study aimed to determine whether mitochondrial function in peripheral blood mononuclear cells (PBMCs) of patients with T2DM-CI was altered and if these alterations could be used as biomarkers.

METHODS

A total of 374 subjects were enrolled, including AD, T2DM-CI, T2DM-nCI (T2DM without cognitive impairment), and healthy controls. The mitochondrial function was determined using a commercial assay kit. The mitochondrial DNA (mtDNA) content, the expression of SIRT1, and selected miRNAs in PBMCs were measured by quantitative polymerase chain reaction. The correlations and diagnostic accuracy were assessed using the Spearman correlation coefficient or receiver operating characteristics analysis, respectively.

RESULTS

We found significant changes in mitochondrial function in PBMCs of patients with AD compared with controls (all P < .05), which were not found in T2DM-CI. However, mtDNA content and SIRT1 mRNA expression were lower in PBMCs of patients with T2DM-CI, while miR-34a-5p expression was higher than in patients with T2DM-nCI (all P < .05). A combination of SIRT1 and miR-34a-5p demonstrated excellent discrimination between T2DM-CI and T2DM-nCI (area under the curve = 0.793; sensitivity: 80.01%; specificity: 78.46%). Furthermore, correlation analysis revealed a link between miR-34a-5p expression and hyperglycemia in T2DM-CI.

CONCLUSION

Our findings revealed that there was an alteration of mitochondria at the peripheral level in patients with T2DM-CI. SIRT1 combined with miR-34a-5p in PBMCs performed well in identifying patients with T2DM-CI and may be a promising biomarker.

Dysregulated miRNA-375, IL-17, TGF-β, and Microminerals Are Associated with Calpain-10 SNP 19 in Diabetic Patients: Correlation with Diabetic Nephropathy Stages

Zinc (Zn) and copper (Cu) have been shown to have the potential to improve glucose metabolism through interactions with cytokines and signaling events with multiple genes. miRNA-375 and the Calpin-10 gene are potential genetic biomarkers for the early prediction of diabetic nephropathy (DN). 128 healthy controls and 129 type 2 diabetic (T2DM) participants were matched for age and sex. Three subgroups were identified from the T2DM group: 39 patients had microalbuminuria, 41 had macroalbuminuria, and 49 patients had renal problems. Circulating miR-375 expression levels were measured via qPCR. Calpain-10 SNP 19 (rs3842570) genotyping was assessed with allele-specific PCR in all the included participants. Spectrophotometry was used to measure the concentrations of serum copper, zinc, and magnesium, while ELISA was used to measure the levels of TGF-β and IL-17. There was significant up-regulation in the expression of miR-375 and serum levels of TGF-β, IL-17, Cu, and the Cu/Zn ratio, whereas, in contrast to the control group, the Zn and Mg levels were lower in the T2DM group. The DN groups had significantly lower miR-375, TGF-β, IL-17, Mg, and Zn levels compared with the T2DM without nephropathy group. Furthermore, between TGF-β, IL-17, and miRNA-375, there were notable correlations. Calpain-10 SNP 19 genotype 22 and allele 2 were linked to a higher incidence of T2DM and DN. Significant TGF-β, Cu, Cu/Zn ratio, HbAc1, and creatinine levels, but insignificant miRNA-375 levels, were associated with genotype 22 of Calpain-10 SNP 19. interactions between the Calpain-10 SNP 19 genotype 22 and IL-17, TGF-β, mineral levels, and miRNA-375 might contribute to the aetiology of DN and T2DM and may have clinical implications for diagnosis and management.

Molecular and Metabolic Analysis of Arsenic-Exposed Humanized AS3MT Mice

BACKGROUND

Chronic exposure to inorganic arsenic (iAs) has been associated with type 2 diabetes (T2D). However, potential sex divergence and the underlying mechanisms remain understudied. iAs is not metabolized uniformly across species, which is a limitation of typical exposure studies in rodent models. The development of a new "humanized" mouse model overcomes this limitation. In this study, we leveraged this model to study sex differences in the context of iAs exposure.

OBJECTIVES

The aim of this study was to determine if males and females exhibit different liver and adipose molecular profiles and metabolic phenotypes in the context of iAs exposure.

METHODS

Our study was performed on wild-type (WT) 129S6/SvEvTac and humanized arsenic + 3 methyl transferase (human AS3MT) 129S6/SvEvTac mice treated with 400   ppb of iAs via drinking water ad libitum. After 1 month, mice were sacrificed and the liver and gonadal adipose depots were harvested for iAs quantification and sequencing-based microRNA and gene expression analysis. Serum blood was collected for fasting blood glucose, fasting plasma insulin, and homeostatic model assessment for insulin resistance (HOMA-IR).

RESULTS

We detected sex divergence in liver and adipose markers of diabetes (e.g., miR-34a, insulin signaling pathways, fasting blood glucose, fasting plasma insulin, and HOMA-IR) only in humanized (not WT) mice. In humanized female mice, numerous genes that promote insulin sensitivity and glucose tolerance in both the liver and adipose are elevated compared to humanized male mice. We also identified Klf11 as a putative master regulator of the sex divergence in gene expression in humanized mice.

DISCUSSION

Our study underscored the importance of future studies leveraging the humanized mouse model to study iAs-associated metabolic disease. The findings suggested that humanized males are at increased risk for metabolic dysfunction relative to humanized females in the context of iAs exposure. Future investigations should focus on the detailed mechanisms that underlie the sex divergence. https://doi.org/10.1289/EHP12785.

MicroRNA-34a Mediates High-Fat-Induced Hepatic Insulin Resistance by Targeting ENO3

The etiology of numerous metabolic disorders is characterized by hepatic insulin resistance (IR). Uncertainty surrounds miR-34a's contribution to high-fat-induced hepatic IR and its probable mechanism. The role and mechanism of miR-34a and its target gene ENO3 in high-fat-induced hepatic IR were explored by overexpressing/suppressing miR-34a and ENO3 levels in in vivo and in vitro experiments. Moreover, as a human hepatic IR model, the miR-34a/ENO3 pathway was validated in patients with non-alcoholic fatty liver disease (NAFLD). The overexpression of hepatic miR-34a lowered insulin signaling and altered glucose metabolism in hepatocytes. In contrast, reducing miR-34a expression significantly reversed hepatic IR indices induced by palmitic acid (PA)/HFD. ENO3 was identified as a direct target gene of miR-34a. Overexpression of ENO3 effectively inhibited high-fat-induced hepatic IR-related indices both in vitro and in vivo. Moreover, the expression patterns of members of the miR-34a/ENO3 pathway in the liver tissues of NAFLD patients was in line with the findings of both cellular and animal studies. A high-fat-induced increase in hepatic miR-34a levels attenuates insulin signaling and impairs glucose metabolism by suppressing the expression of its target gene ENO3, ultimately leading to hepatic IR. The miR-34a/ENO3 pathway may be a potential therapeutic target for hepatic IR and related metabolic diseases.

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

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

Elevated miR-143 and miR-34a gene expression in human visceral adipose tissue are associated with insulin resistance in non-diabetic adults: a cross-sectional study

OBJECTIVE

We aimed to evaluate the association of miR-143 and miR-34a expression in human visceral (VAT) and subcutaneous (SAT) adipose tissues with insulin resistance (IR).

METHODS

VAT and SAT were obtained from 176 participants without diabetes. miR-143 and miR-34a expressions in VAT and SAT were measured using qRT-PCR. Fasting serum insulin and glucose concentration, homeostatic model assessment of IR index (HOMA-IR) and β-cell function (HOMA-B), and quantitative insulin-sensitivity check index (QUICKI) were calculated.

RESULTS

After adjustment for age, sex and body mass index (BMI), VAT miR-143 expression was positively associated with fasting plasma glucose (FPG), insulin, and HOMA-IR, and negatively associated with HOMA-B and QUICKI. miR-34a expression in VAT was directly associated with FPG, insulin, and HOMA-IR and negatively associated with QUICKI. In SAT, miR-34a expression was positively associated with insulin and negatively associated with QUICKI. The interaction terms of HOMA-IR and BMI categories were significant for both miR gene expressions in VAT. After stratifying participants based on BMI, the association of miR-143 and miR-34a expressions in VAT with IR indices remained significant only in obese patients.

CONCLUSION

miR-143 and miR-34a expressions in VAT were independent predictors of IR in people without diabetes, and that this association was conditional on the degree of obesity.

LEVEL OF EVIDENCE

Level of evidence III, cross-sectional analytic study.

Circulating microRNAs as clinically useful biomarkers for Type 2 Diabetes Mellitus: miRNomics from bench to bedside

Type 2 diabetes (T2D), a chronic metabolic disease, has attained the status of a global epidemic with steadily increasing incidence worldwide. Improved diagnosis, stratification and prognosis of T2D patients and the development of more effective treatments are needed. In this era of personalized medicine, the discovery and evaluation of innovative circulating biomarkers can be an effective tool for better stratification, prognosis and therapeutic selection/management of T2D patients. MicroRNAs (miRNAs), a class of small non-coding RNAs that modulate gene expression, have been investigated as potential circulating biomarkers in T2D. Several studies have investigated the expression of circulating miRNAs in T2D patients from various biological fluids, including plasma and serum, and have demonstrated their potential as diagnostic and prognostic biomarkers, as well as biomarkers of response to therapy. In this review, we provide an overview of the current state of knowledge, focusing on circulating miRNAs that have been consistently expressed in at least two independent studies, in order to identify a set of consistent biomarker candidates in T2D. The expression levels of miRNAs, correlation with clinical parameters, functional roles of miRNAs and their potential as biomarkers are reported. A systematic literature search and assessment of studies led to the selection and review of 10 miRNAs (miR-126-3p, miR-223-3p, miR-21-5p, miR-15a-5p, miR-24-3p, miR-34a-5p, miR-146a-5p, miR-148a-3p, miR-30d-5p and miR-30c-5p). We also present technical challenges and our thoughts on the potential validation of circulating miRNAs and their application as biomarkers in the context of T2D.

Effect of Anti-Osteoporotic Treatments on Circulating and Bone MicroRNA Patterns in Osteopenic ZDF Rats

Bone fragility is an adverse outcome of type 2 diabetes mellitus (T2DM). The underlying molecular mechanisms have, however, remained largely unknown. MicroRNAs (miRNAs) are short non-coding RNAs that control gene expression in health and disease states. The aim of this study was to investigate the genome-wide regulation of miRNAs in T2DM bone disease by analyzing serum and bone tissue samples from a well-established rat model of T2DM, the Zucker Diabetic Fatty (ZDF) model. We performed small RNA-sequencing analysis to detect dysregulated miRNAs in the serum and ulna bone of the ZDF model under placebo and also under anti-sclerostin, PTH, and insulin treatments. The dysregulated circulating miRNAs were investigated for their cell-type enrichment to identify putative donor cells and were used to construct gene target networks. Our results show that unique sets of miRNAs are dysregulated in the serum (n = 12, FDR < 0.2) and bone tissue (n = 34, FDR < 0.2) of ZDF rats. Insulin treatment was found to induce a strong dysregulation of circulating miRNAs which are mainly involved in metabolism, thereby restoring seven circulating miRNAs in the ZDF model to normal levels. The effects of anti-sclerostin treatment on serum miRNA levels were weaker, but affected miRNAs were shown to be enriched in bone tissue. PTH treatment did not produce any effect on circulating or bone miRNAs in the ZDF rats. Altogether, this study provides the first comprehensive insights into the dysregulation of bone and serum miRNAs in the context of T2DM and the effect of insulin, PTH, and anti-sclerostin treatments on circulating miRNAs.

Key regulatory miRNAs in lipid homeostasis: implications for cardiometabolic diseases and development of novel therapeutics

Dysregulation of lipid metabolism is associated with cardiovascular/metabolic diseases, including atherosclerosis, liver diseases and type 2 diabetes mellitus (T2DM). Several miRNAs have been reported as regulators of different stages of lipid homeostasis, including cholesterol/fatty acid biosynthesis, degradation, transport, storage, and low-density (LDL) and high-density lipoprotein (HDL) formation. Indeed, various miRNAs are emerging as attractive therapeutic candidates for metabolic/cardiovascular disease (CVD). Here, we summarize the roles of miR-19b, miR-20a, miR-21, miR-27, miR-29, miR-34a, miR-144, miR-148a, and miR-199a in post-transcriptional regulation of genes involved in lipid metabolism and their therapeutic potential. We also discuss experimental strategies for further development of these miRNAs as novel cardiometabolic therapeutics. Teaser: miRNAs have emerged as crucial regulators of lipid homeostasis. Here, we highlight key miRNAs that regulate lipid metabolism and their therapeutic potential in cardiometabolic disease states.

Regulation of microRNAs in Alzheimer´s disease, type 2 diabetes, and aerobic exercise training

Alzheimer's disease (AD) is the most common type of dementia. The evolution and aggregation of amyloid beta (β) oligomers is linked to insulin resistance in AD, which is also the major characteristic of type 2 diabetes (T2D). Being physically inactive can contribute to the development of AD and/or T2D. Aerobic exercise training (AET), a type of physical exercise, can be useful in preventing or treating the negative outcomes of AD and T2D. AD, T2D and AET can regulate the expression of microRNAs (miRNAs). Here, we review some of the changes in miRNAs expression regulated by AET, AD and T2D. MiRNAs play an important role in the gene regulation of key signaling pathways in both pathologies, AD and T2D. MiRNA dysregulation is evident in AD and has been associated with several neuropathological alterations, such as the development of a reactive gliosis. Expression of miRNAs are associated with many pathophysiological mechanisms involved in T2D like insulin synthesis, insulin resistance, glucose intolerance, hyperglycemia, intracellular signaling, and lipid profile. AET regulates miRNAs levels. We identified 5 miRNAs (miR-21, miR-29a/b, miR-103, miR-107, and miR-195) that regulate gene expression and are modulated by AET on AD and T2D. The identified miRNAs are potential targets to treat the symptoms of AD and T2D. Thus, AET is a non-pharmacological tool that can be used to prevent and fight the negative outcomes in AD and T2D.

Characteristic MicroRNAs Linked to Dysregulated Metabolic Pathways in Qatari Adult Subjects With Obesity and Metabolic Syndrome

BACKGROUND

Obesity-associated dysglycemia is associated with metabolic disorders. MicroRNAs (miRNAs) are known regulators of metabolic homeostasis. We aimed to assess the relationship of circulating miRNAs with clinical features in obese Qatari individuals.

METHODS

We analyzed a dataset of 39 age-matched patients that includes 18 subjects with obesity only (OBO) and 21 subjects with obesity and metabolic syndrome (OBM). We measured 754 well-characterized human microRNAs (miRNAs) and identified differentially expressed miRNAs along with their significant associations with clinical markers in these patients.

RESULTS

A total of 64 miRNAs were differentially expressed between metabolically healthy obese (OBO) versus metabolically unhealthy obese (OBM) patients. Thirteen out of 64 miRNAs significantly correlated with at least one clinical trait of the metabolic syndrome. Six out of the thirteen demonstrated significant association with HbA1c levels; miR-331-3p, miR-452-3p, and miR-485-5p were over-expressed, whereas miR-153-3p, miR-182-5p, and miR-433-3p were under-expressed in the OBM patients with elevated HbA1c levels. We also identified, miR-106b-3p, miR-652-3p, and miR-93-5p that showed a significant association with creatinine; miR-130b-5p, miR-363-3p, and miR-636 were significantly associated with cholesterol, whereas miR-130a-3p was significantly associated with LDL. Additionally, miR-652-3p's differential expression correlated significantly with HDL and creatinine.

CONCLUSIONS

MicroRNAs associated with metabolic syndrome in obese subjects may have a pathophysiologic role and can serve as markers for obese individuals predisposed to various metabolic diseases like diabetes.

Circulating Nucleic Acid-Based Biomarkers of Type 2 Diabetes

Type 2 diabetes (T2D) is a deficiency in how the body regulates glucose. Uncontrolled T2D will result in chronic high blood sugar levels, eventually resulting in T2D complications. These complications, such as kidney, eye, and nerve damage, are even harder to treat. Identifying individuals at high risk of developing T2D and its complications is essential for early prevention and treatment. Numerous studies have been done to identify biomarkers for T2D diagnosis and prognosis. This review focuses on recent T2D biomarker studies based on circulating nucleic acids using different omics technologies: genomics, transcriptomics, and epigenomics. Omics studies have profiled biomarker candidates from blood, urine, and other non-invasive samples. Despite methodological differences, several candidate biomarkers were reported for the risk and diagnosis of T2D, the prognosis of T2D complications, and pharmacodynamics of T2D treatments. Future studies should be done to validate the findings in larger samples and blood-based biomarkers in non-invasive samples to support the realization of precision medicine for T2D.

miR-21 and miR-146a: The microRNAs of inflammaging and age-related diseases

The first paper on "inflammaging" published in 2001 paved the way for a unifying theory on how and why aging turns out to be the main risk factor for the development of the most common age-related diseases (ARDs). The most exciting challenge on this topic was explaining how systemic inflammation steeps up with age and why it shows different rates among individuals of the same chronological age. The "epigenetic revolution" in the past twenty years conveyed that the assessment of the individual genetic make-up is not enough to depict the trajectories of age-related inflammation. Accordingly, others and we have been focusing on the role of non-coding RNA, i.e. microRNAs (miRNAs), in inflammaging. The results obtained in the latest 10 years underpinned the key role of a miRNA subset that we have called inflammamiRs, owing to their ability to master (NF-κB)-driven inflammatory pathways. In this review, we will focus on two inflammamiRs, i.e. miR-21-5p and miR-146a-5p, which target a variety of molecules belonging to the NF-κB/NLRP3 pathways. The interplay between miR-146a-5p and IL-6 in the context of aging and ARDs will also be highlighted. We will also provide the most relevant evidence suggesting that circulating inflammamiRs, along with IL-6, can measure the degree of inflammaging.

The association of circulating miR-191 and miR-375 expression levels with markers of insulin resistance in overweight children: an exploratory analysis of the I.Family Study

Background

In recent years, the exciting emergence of circulating miRNAs as stable, reproducible, and consistent among individuals has opened a promising research opportunity for the detection of non-invasive biomarkers. A firm connection has been established between circulating miRNAs and glycaemic as well as metabolic homeostasis, showing that levels of specific miRNAs vary under different physio-pathological conditions.

Objective

In this pilot study, we investigated the expression of candidate miRNAs, hsa-miR-191-3p and hsa-miR-375, in relation to biomarkers associated with insulin sensitivity in a subgroup (n=58) of subjects participating to the European I.Family Study, a project aimed to assess the determinants of eating behaviour in children and adolescents and related health outcomes. The sample included overweight/obese children/adolescents since overweight/obesity is a known risk factor for impaired glucose homeostasis and metabolic disorders. Biological targets of candidate miRNAs were also explored in silico.

Results

We observed a significant association of the two miRNAs and early changes in glycaemic homeostasis, independent of covariates including country of origin, age, BMI z-score, puberty status, highest educational level of parents, total energy intake, energy from fats, energy from carbohydrates, and energy from proteins.

Conclusion

Identification of circulating miRNAs associated with insulin impairment may offer novel approaches of assessing early variations in insulin sensitivity and provide evidence about the molecular mechanisms connected to early changes in glycaemic homeostasis.

Trial registration

ISRCTN, ISRCTN62310987. Retrospectively registered, http://isrctn.com/ISRCTN62310987

Supplementary Information

The online version contains supplementary material available at 10.1186/s12263-021-00689-1.

Silencing of circHIPK3 hampers platelet-derived growth factor-induced proliferation and migration in airway smooth muscle cells through the miR-375/MMP-16 axis

Emerging evidence has suggested a pivotal role of circular RNAs (circRNAs) in the progression of asthma. In this paper, we explored the mechanisms underlying the modulation of circRNA homeodomain interacting protein kinase 3 (circHIPK3, circ_0000284) in airway smooth muscle cell (AMSC) migration and proliferation induced by platelet-derived growth factor (PDGF). The stability of circHIPK3 was gauged by Ribonuclease R (RNase R) and Actinomycin D assays. Relative expression levels of circHIPK3, microRNA (miR)-375 and matrix metallopeptidase 16 (MMP-16) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Cell proliferation, invasion, and apoptosis were evaluated by Cell Counting Kit-8 (CCK-8) assay, transwell assay, and flow cytometry, respectively. Cell migration was detected by wound-healing and transwell assays. Direct relationship between miR-375 and circHIPK3 or MMP-16 was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Our results indicated that PDGF induced the expression of circHIPK3 in human AMSCs (HAMSCs). CircHIPK3 silencing impeded proliferation, migration, invasion and promoted apoptosis of PDGF-treated HAMSCs. Mechanistically, circHIPK3 targeted miR-375 by directly binding to miR-375. MiR-375 was a downstream effector of circHIPK3 in controlling PDGF-induced proliferation, invasion and migration. MMP-16 was directly targeted and inhibited by miR-375, and circHIPK3 functioned as a post-transcriptional modulator of MMP-16 expression through miR-375. Moreover, miR-375-mediated inhibition of MMP-16 impacted HAMSC proliferation, invasion and migration induced by PDGF. Our findings identified the miR-375/MMP-16 axis as a novel mechanism for the modulation of circHIPK3 in PDGF-induced migration and proliferation in HASMCs.

MicroRNA Sequences Modulated by Beta Cell Lipid Metabolism: Implications for Type 2 Diabetes Mellitus

Alterations in lipid metabolism within beta cells and islets contributes to dysfunction and apoptosis of beta cells, leading to loss of insulin secretion and the onset of type 2 diabetes. Over the last decade, there has been an explosion of interest in understanding the landscape of gene expression which influences beta cell function, including the importance of small non-coding microRNA sequences in this context. This review sought to identify the microRNA sequences regulated by metabolic challenges in beta cells and islets, their targets, highlight their function and assess their possible relevance as biomarkers of disease progression in diabetic individuals. Predictive analysis was used to explore networks of genes targeted by these microRNA sequences, which may offer new therapeutic strategies to protect beta cell function and delay the onset of type 2 diabetes.

Non-Coding RNAs Based Molecular Links in Type 2 Diabetes, Ischemic Stroke, and Vascular Dementia

This article reviews recent advances in the study of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and their functions in type 2 diabetes mellitus (T2DM), ischemic stroke (IS), and vascular dementia (VaD). miRNAs and lncRNAs are gene regulation markers that both regulate translational aspects of a wide range of proteins and biological processes in healthy and disease states. Recent studies from our laboratory and others have revealed that miRNAs and lncRNAs expressed differently are potential therapeutic targets for neurological diseases, especially T2DM, IS, VaD, and Alzheimer's disease (AD). Currently, the effect of aging in T2DM, IS, and VaD and the cellular and molecular pathways are largely unknown. In this article, we highlight results from the works on the molecular connections between T2DM and IS, and IS and VaD. In each disease, we also summarize the pathophysiology and the differential expressions of miRNAs and lncRNAs. Based on current research findings, we hypothesize that 1) T2DM bi-directionally and age-dependently induces IS and VaD, and 2) these changes are precursors to the onset of dementia in elderly people. Research into these hypotheses is required to examine further whether research efforts on reducing T2DM, IS, and VaD may affect dementia and/or delay the AD disease process in the aged population.

The antioxidant and anti-inflammatory effects of astaxanthin supplementation on the expression of miR-146a and miR-126 in patients with type 2 diabetes mellitus: A randomised, double-blind, placebo-controlled clinical trial

BACKGROUND

The pathogenesis of type 2 diabetes mellitus (T2DM) is associated with chronic oxidative stress and inflammation. It is well known that the expression of some miRNAs such as miRNA-146a is upregulated in diabetic and hyperglycaemic patients, whereas circulating miRNA-126 is reduced. Therefore, we aimed to determine the effects of astaxanthin (AST) supplementation on the circulating malondialdehyde (MDA) and interleukin 6 (IL-6) levels, and the expression of miR-146a and miR-126 in patients with T2DM.

METHODS

This randomised, double-blind, placebo-controlled clinical trial was conducted in 44 patients with T2DM randomly receiving 8 mg/d of oral AST (n = 22) or placebo (n = 22) for 8 weeks.

RESULTS

We observed that AST supplementation could decrease plasma levels of MDA and IL-6 (P < .05) and decrease the expression level of miR-146a over time (fold change: -1/388) (P < .05).

CONCLUSION

AST supplementation might be beneficial for improving circulating MDA and IL-6 and the down-regulation of miR-146a. However, future investigations are suggested to confirm these results.

MicroRNAs, Parkinson's Disease, and Diabetes Mellitus

Parkinson’s disease (PD) is a neurodegenerative disorder that affects 1% of the population over the age of 60. Diabetes Mellitus (DM) is a metabolic disorder that affects approximately 25% of adults over the age of 60. Recent studies showed that DM increases the risk of developing PD. The link between DM and PD has been discussed in the literature in relation to different mechanisms including mitochondrial dysfunction, oxidative stress, and protein aggregation. In this paper, we review the common microRNA (miRNA) biomarkers of both diseases. miRNAs play an important role in cell differentiation, development, the regulation of the cell cycle, and apoptosis. They are also involved in the pathology of many diseases. miRNAs can mediate the insulin pathway and glucose absorption. miRNAs can also regulate PD-related genes. Therefore, exploring the common miRNA biomarkers of both PD and DM can shed a light on how these two diseases are correlated, and targeting miRNAs is a potential therapeutic opportunity for both diseases.

MicroRNA-34a: the bad guy in age-related vascular diseases

The age-related vasculature alteration is the prominent risk factor for vascular diseases (VD), namely, atherosclerosis, abdominal aortic aneurysm, vascular calcification (VC) and pulmonary arterial hypertension (PAH). The chronic sterile low-grade inflammation state, alias inflammaging, characterizes elderly people and participates in VD development. MicroRNA34-a (miR-34a) is emerging as an important mediator of inflammaging and VD. miR-34a increases with aging in vessels and induces senescence and the acquisition of the senescence-associated secretory phenotype (SASP) in vascular smooth muscle (VSMCs) and endothelial (ECs) cells. Similarly, other VD risk factors, including dyslipidemia, hyperglycemia and hypertension, modify miR-34a expression to promote vascular senescence and inflammation. miR-34a upregulation causes endothelial dysfunction by affecting ECs nitric oxide bioavailability, adhesion molecules expression and inflammatory cells recruitment. miR-34a-induced senescence facilitates VSMCs osteoblastic switch and VC development in hyperphosphatemia conditions. Conversely, atherogenic and hypoxic stimuli downregulate miR-34a levels and promote VSMCs proliferation and migration during atherosclerosis and PAH. MiR34a genetic ablation or miR-34a inhibition by anti-miR-34a molecules in different experimental models of VD reduce vascular inflammation, senescence and apoptosis through sirtuin 1 Notch1, and B-cell lymphoma 2 modulation. Notably, pleiotropic drugs, like statins, liraglutide and metformin, affect miR-34a expression. Finally, human studies report that miR-34a levels associate to atherosclerosis and diabetes and correlate with inflammatory factors during aging. Herein, we comprehensively review the current knowledge about miR-34a-dependent molecular and cellular mechanisms activated by VD risk factors and highlight the diagnostic and therapeutic potential of modulating its expression in order to reduce inflammaging and VD burn and extend healthy lifespan.

miR-18a increases insulin sensitivity by inhibiting PTEN

The miR-17-92 cluster (miR-17, miR-18a, miR-19a, miR-20a, miR-19b-1 and miR-92a) contributes to the occurrence and development of various diseases by inhibiting multiple target genes. Here, we explored the effects of miR-18a on insulin sensitivity. Quantitative real-time PCR indicated that serum miR-18a levels were lower in type 2 diabetes mellitus patients than in healthy controls, suggesting that miR-18a may influence blood glucose levels. Global overexpression of miR-18a in transgenic mice increased their glucose tolerance and insulin sensitivity, while it reduced expression of the phosphatase and tensin homolog deleted on chromosome ten (PTEN) in their skeletal muscle and adipose tissue. Western blotting indicated that overexpressing miR-18a in 3T3-L1 and C2C12 cells enhanced insulin-stimulated AKT phosphorylation and suppressed PTEN expression, while inhibiting miR-18a had the opposite effects. These results suggest that miR-18a improves insulin sensitivity by downregulating PTEN. This makes miR-18a a potentially useful target for the treatment of diabetes mellitus in the future.