Diagnostic Value of Cell-free Circulating MicroRNAs for Obesity and Type 2 Diabetes: A Meta-analysis

Effects of Phytochemicals on Type 2 Diabetes via MicroRNAs

PURPOSE OF REVIEW

Type 2 diabetes, characterized by inadequate insulin secretion and resistance, is increasingly prevalent. To effectively manage type 2 diabetes, identifying new therapeutic targets is crucial. MicroRNAs, short noncoding RNA molecules, play a pivotal role in regulating β-cell function, insulin production, and resistance, and show promise as biomarkers for predicting type 2 diabetes onset. Phytochemicals, known for their antioxidant activities, may influence microRNA expression, potentially improving insulin sensitivity and mitigating associated complications. This review aims to explore the significance of microRNA in type 2 diabetes, their potential as biomarkers, and how certain phytochemicals may modulate microRNA expressions to reduce or prevent diabetes and its complications.

RECENT FINDINGS

Current research suggests that microRNAs show promise as novel therapeutic biomarkers for diagnosing type 2 diabetes and monitoring diabetic complications. Additionally, phytochemicals may regulate microRNAs to control type 2 diabetes, presenting a potential therapeutic strategy. The multifactorial effects of phytochemicals on type 2 diabetes and its complications through microRNAs warrant further research to elucidate their mechanisms. Comprehensive clinical trials are needed to assess the safety and efficacy of phytochemicals and their combinations. Given their ability to modulate microRNAs expression, incorporating phytochemical-rich foods into the diet may be beneficial.

Links among Obesity, Type 2 Diabetes Mellitus, and Osteoporosis: Bone as a Target

Obesity, type 2 diabetes mellitus (T2DM) and osteoporosis are serious diseases with an ever-increasing incidence that quite often coexist, especially in the elderly. Individuals with obesity and T2DM have impaired bone quality and an elevated risk of fragility fractures, despite higher and/or unchanged bone mineral density (BMD). The effect of obesity on fracture risk is site-specific, with reduced risk for several fractures (e.g., hip, pelvis, and wrist) and increased risk for others (e.g., humerus, ankle, upper leg, elbow, vertebrae, and rib). Patients with T2DM have a greater risk of hip, upper leg, foot, humerus, and total fractures. A chronic pro-inflammatory state, increased risk of falls, secondary complications, and pharmacotherapy can contribute to the pathophysiology of aforementioned fractures. Bisphosphonates and denosumab significantly reduced the risk of vertebral fractures in patients with both obesity and T2DM. Teriparatide significantly lowered non-vertebral fracture risk in T2DM subjects. It is important to recognize elevated fracture risk and osteoporosis in obese and T2DM patients, as they are currently considered low risk and tend to be underdiagnosed and undertreated. The implementation of better diagnostic tools, including trabecular bone score, lumbar spine BMD/body mass index (BMI) ratio, and microRNAs to predict bone fragility, could improve fracture prevention in this patient group.

Decreased Serum Levels of the Insulin Resistance-Related microRNA miR-320a in Patients with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is often associated with metabolic abnormalities in the affected patients such as obesity or a dysregulated glucose metabolism/insulin resistance (IR). IR affects the serum levels of several circulating microRNAs; however, studies on the association between IR-related microRNAs and PCOS are scarce. Therefore, we quantified the serum levels of the IR-associated microRNAs miR-93, miR-148a, miR-216a, miR-224 and miR-320a via qPCR in a cohort of 358 infertility patients, of whom 136 were diagnosed with PCOS. In bivariate correlation analyses, the serum levels of miR-93 and miR-216a were inversely associated with dipeptidyl peptidase 4 serum concentrations, and the miR-320a serum levels were significantly downregulated in PCOS patients (p = 0.02, Mann-Whitney U test). Interestingly, in all patients who achieved pregnancy after Assisted Reproductive Technology (ART) cycles, the serum levels of the five IR-associated microRNAs were significantly elevated compared to those of non-pregnant patients. In cell culture experiments, we detected a significant upregulation of miR-320a expression following testosterone stimulation over 24 and 48 h in KGN and COV434 granulosa carcinoma cells. In conclusion, we demonstrated a significantly reduced serum level of the IR-associated miR-320a in our patient cohort. This result once again demonstrates the close relationship between metabolic disorders and the dysregulation of microRNA expression patterns in PCOS.

Downregulation of miR-4284 can Inhibit the Apoptosis of Human Arterial Smooth Muscle Cells (HASMCs) in Arteriosclerosis Obliterans (ASO)

INTRODUCTION

The disease arteriosclerosis obliterans (ASO) affects the lower extremities. ASO's mechanism involves the proliferation and migration of vascular smooth muscle cells (VSMCs). The miR-4284 is involved in several biological processes of the cardiovascular system, including VSMC proliferation, migration, and death. However, it is unknown if the miR-4284 gene is involved in the control of ASO. Furthermore, the molecular processes behind the contribution of human arterial smooth muscle cells (HASMCs), one of the most significant components of the arterial wall, to arteriosclerosis obliterans (ASO) pathogenesis remain unknown. Previously, we explored the alterations of miRNAs in the blood of ASO patients, and now we wanted to test further whether these changes also take place in the HASMCs that are responsible for the pathogenesis of ASO.

METHODS

The expression levels of miR-29a in arterial walls were analyzed via a real-time polymerase chain reaction. An ASO cell model was established to investigate the expression of miR- 4284 on HASMCs. The Transwell system and CCK-8 detection were used to assess the migration and proliferation of HASMCs. The proportion of apoptotic cells as well as the concentrations of apoptotic signal protein production were assessed using flow cytometry. A Western blot technique was used to identify B cell lymphoma-2 (Bcl2), Bcl2-associated X protein (BAX), as well as Xlinked inhibitors of apoptosis protein (XIAP).

RESULTS

The results showed that PCR confirmed that the qualified production or expression of miR-4284 was significantly reduced in HASMCs after they were cultured without FBS and in an atmosphere of 1% O2 + 5% CO2 + 94% N2 and that glucose had no effect on its expression. MiR- 4284 has no effect on migration and proliferation, but downregulation of miR-4284 can decrease the apoptotic rate of HASMCs, as revealed by flow cytometry. Furthermore, western blot experiments showed that the expression of BAX was low, while the expression of the other two proteins, viz., Bcl2 and XIAP, was over-expressed.

CONCLUSION

We found that miR-4284 downregulation enhanced Bcl2, as well as XIAP, and decreased Bax. This shows that downregulated miR-4284 regulates apoptosis-related protein expression in HASMCs. The mechanism is not clear, and we need further study to confirm it.

Network analysis identifies circulating miR-155 as predictive biomarker of type 2 diabetes mellitus development in obese patients: a pilot study

Obesity is the main risk factor for many non-communicable diseases. In clinical practice, unspecific markers are used for the determination of metabolic alterations and inflammation, without allowing the characterization of subjects at higher risk of complications. Circulating microRNAs represent an attractive approach for early screening to identify subjects affected by obesity more at risk of developing connected pathologies. The aim of this study was the identification of circulating free and extracellular vesicles (EVs)-embedded microRNAs able to identify obese patients at higher risk of type 2 diabetes (DM2). The expression data of circulating microRNAs derived from obese patients (OB), with DM2 (OBDM) and healthy donors were combined with clinical data, through network-based methodology implemented by weighted gene co-expression network analysis. The six circulating microRNAs overexpressed in OBDM patients were evaluated in a second group of patients, confirming the overexpression of miR-155-5p in OBDM patients. Interestingly, the combination of miR-155-5p with serum levels of IL-8, Leptin and RAGE was useful to identify OB patients most at risk of developing DM2. These results suggest that miR-155-5p is a potential circulating biomarker for DM2 and that the combination of this microRNA with other inflammatory markers in OB patients can predict the risk of developing DM2.

Environmental and Lifestyle Cancer Risk Factors: Shaping Extracellular Vesicle OncomiRs and Paving the Path to Cancer Development

Intercellular communication has been transformed by the discovery of extracellular vesicles (EVs) and their cargo, including microRNAs (miRNAs), which play crucial roles in intercellular signaling. These EVs were previously disregarded as cellular debris but are now recognized as vital mediators of biological information transfer between cells. Furthermore, they respond not only to internal stimuli but also to environmental and lifestyle factors. Identifying EV-borne oncomiRs, a subset of miRNAs implicated in cancer development, could revolutionize our understanding of how environmental and lifestyle exposures contribute to oncogenesis. To investigate this, we studied the plasma levels of EV-borne oncomiRs in a population of 673 women and 238 men with a body mass index > 25 kg/m2 (SPHERE population). The top fifty oncomiRs associated with the three most common cancers in women (breast, colorectal, and lung carcinomas) and men (lung, prostate, and colorectal carcinomas) were selected from the OncomiR database. Only oncomiRs expressed in more than 20% of the population were considered for statistical analysis. Using a Multivariate Adaptive Regression Splines (MARS) model, we explored the interactions between environmental/lifestyle exposures and EV oncomiRs to develop optimized predictor combinations for each EV oncomiR. This innovative approach allowed us to better understand miRNA regulation in response to multiple environmental and lifestyle influences. By uncovering non-linear relationships among variables, we gained valuable insights into the complexity of miRNA regulatory networks. Ultimately, this research paves the way for comprehensive exposome studies in the future.

Whole-Body Cryotherapy Alters Circulating MicroRNA Profile in Postmenopausal Women

The incidence of metabolic syndrome (MetS) increases with age, especially in women. The role of microRNAs (miRs) in the regulation of metabolism is postulated. The aim of the study is to identify miRs that may be markers of MetS and to assess changes in miRs expression as a result of 10 and 20 whole-body cryotherapy treatments (WBC; 3 min, -120 °C) in postmenopausal women with MetS (M-60, BMI 30.56 ± 5.38 kg/m2), compared to healthy postmenopausal (H-60, BMI 25.57 ± 2.46 kg/m2) and healthy young women (H-20, BMI 22.90 ± 3.19 kg/m2). In a fasting state, before 1 WBC and after 10 WBCs, as well as 20 WBCs, the expression of miR-15a-5p, miR-21-5p, miR-23a-3p, miR-146a-5p, miR-197-3p, miR-223-3p, fasting blood glucose (FBG) and blood lipid profile were determined. miR-15a-5p and miR-21-5p were down-regulated in M-60, while miR-23a-3p and miR-197-3p were up-regulated, and miR-223-3p down-regulated in M-60 and H-60, compared to H-20. Significant positive correlations between up-regulated (mostly for miR-23-3p and miR-197-3p) and significant negative correlations between down-regulated (mostly for miR-15a-5p) miRs and markers of body composition as well as metabolic disorders were observed. After 20 WBCs, miR-15a-5p expression was up-regulated in all groups. In H-60, down-regulation of miR-197-3p expression occurred after 10 WBCs and 20 WBCs. Following 10 WBCs, FBG decreased in all groups, which intensified in M-60 post-20 WBCs. In our research, it has been shown that miR-23a-3p and miR-197-3p are accurate markers of MetS and MetS risk factors, while miR-15a-5p and miR-23a-3p are precise markers of body composition disorders. WBC is an effective treatment for up-regulating miR-15a-5p and lowering glucose levels in young and postmenopausal women and down-regulating miR-197-3p expression in postmenopausal women. It may be an adjunctive effective treatment method in MetS and hyperglycemia.

A Review of micro RNAs changes in T2DM in animals and humans

Type 2 diabetes mellitus (T2DM) and its associated complications have become a crucial public health concern in the world. According to the literature, chronic inflammation and the progression of T2DM have a close relationship. Accumulated evidence suggests that inflammation enhances the insulin secretion lost by islets of Langerhans and the resistance of target tissues to insulin action, which are two critical features in T2DM development. Based on recently highlighted research that plasma concentration of inflammatory mediators such as tumor necrosis factor α and interleukin-6 are elevated in insulin-resistant and T2DM, and it raises novel question marks about the processes causing inflammation in both situations. Over the past few decades, microRNAs (miRNAs), a class of short, noncoding RNA molecules, have been discovered to be involved in the regulation of inflammation, insulin resistance, and T2DM pathology. These noncoding RNAs are specifically comprised of RNA-induced silencing complexes and regulate the expression of specific protein-coding genes through various mechanisms. There is extending evidence that describes the expression profile of a special class of miRNA molecules altered during T2DM development. These modifications can be observed as potential biomarkers for the diagnosis of T2DM and related diseases. In this review study, after reviewing the possible mechanisms involved in T2DM pathophysiology, we update recent information on the miRNA roles in T2DM, inflammation, and insulin resistance.

Connecting the dots in the associations between diet, obesity, cancer, and microRNAs

The prevalence of obesity has reached pandemic levels worldwide, leading to a lower quality of life and higher health costs. Obesity is a major risk factor for noncommunicable diseases, including cancer, although obesity is one of the major preventable causes of cancer. Lifestyle factors, such as dietary quality and patterns, are also closely related to the onset and development of obesity and cancer. However, the mechanisms underlying the complex association between diet, obesity, and cancer remain unclear. In the past few decades, microRNAs (miRNAs), a class of small non-coding RNAs, have been demonstrated to play critical roles in biological processes such as cell differentiation, proliferation, and metabolism, highlighting their importance in disease development and suppression and as therapeutic targets. miRNA expression levels can be modulated by diet and are involved in cancer and obesity-related diseases. Circulating miRNAs can also mediate cell-to-cell communications. These multiple aspects of miRNAs present challenges in understanding and integrating their mechanism of action. Here, we introduce a general consideration of the associations between diet, obesity, and cancer and review the current knowledge of the molecular functions of miRNA in each context. A comprehensive understanding of the interplay between diet, obesity, and cancer could be valuable for the development of effective preventive and therapeutic strategies in future.

Change Profiles and Functional Targets of MicroRNAs in Type 2 Diabetes Mellitus Patients with Obesity

BACKGRUOUND

MicroRNAs (miRNAs) exert an essential contribution to obesity and type 2 diabetes mellitus (T2DM). This study aimed to investigate the differences of miRNAs in the presence and absence of T2DM in patients with obesity, as well as before and after bariatric surgery in T2DM patients with obesity. Characterization of the common changes in both was further analyzed.

METHODS

We enrolled 15 patients with obesity but without T2DM and 15 patients with both obesity and T2DM. Their preoperative clinical data and serum samples were collected, as well as 1 month after bariatric surgery. The serum samples were analyzed by miRNA sequencing, and the miRNAs profiles and target genes characteristics were compared.

RESULTS

Patients with T2DM had 16 up-regulated and 32 down-regulated miRNAs compared to patients without T2DM. Improvement in metabolic metrics after bariatric surgery of T2DM patients with obesity was correlated with changes in miRNAs, as evidenced by the upregulation of 20 miRNAs and the downregulation of 30 miRNAs. Analysis of the two miRNAs profiles identified seven intersecting miRNAs that showed opposite changes. The target genes of these seven miRNAs were substantially enriched in terms or pathways associated with T2DM.

CONCLUSION

We determined the expression profiles of miRNAs in the obese population, with and without diabetes, before and after bariatric surgery. The miRNAs that intersected in the two comparisons were discovered. Both the miRNAs discovered and their target genes were closely associated with T2DM, demonstrating that they might be potential targets for the regulation of T2DM.

Circulating microRNA as Biomarkers for Gestational Diabetes Mellitus-A Systematic Review and Meta-Analysis

Gestational diabetes mellitus (GDM) is a severe pregnancy complication for both the woman and the child. Women who suffer from GDM have a greater risk of developing Type 2 diabetes mellitus (T2DM) later in life. Identification of any potential biomarkers for the early prediction of gestational diabetes can help prevent the disease in women with a high risk. Studies show microRNA (miRNA) as a potential biomarker for the early discovery of GDM, but there is a lack of clarity as to which miRNAs are consistently altered in GDM. This study aimed to perform a systematic review and meta-analysis to investigate miRNAs associated with GDM by comparing GDM cases with normoglycemic controls. The systematic review was performed according to PRISMA guidelines with searches in PubMed, Web of Science, and ScienceDirect. The primary search resulted in a total of 849 articles, which were screened according to the prior established inclusion and exclusion criteria. Following the screening of articles, the review was based on the inclusion of 35 full-text articles, which were evaluated for risk of bias and estimates of quality, after which data were extracted and relative values for miRNAs were calculated. A meta-analysis was performed for the miRNA species investigated in three or more studies: MiR-29a, miR-330, miR-134, miR-132, miR-16, miR-223, miR-155, miR-122, miR-17, miR-103, miR-125, miR-210, and miR-222. While some miRNAs showed considerable between-study variability, miR-29a, miR-330, miR-134, miR-16, miR-223, and miR-17 showed significant overall upregulation in GDM, while circulating levels of miR-132 and miR-155 were decreased among GDM patients, suggesting further studies of these as biomarkers for early GDM discovery.

Dysregulation of Mir-193B and Mir-376A as a Biomarker of Prediabetes in Offspring of Gestational Diabetic Mice

Gestational diabetes mellitus (GDM) is a type of diabetes initiated during pregnancy and is characterized by maternal hyperglycemia that induces complications in mothers and children. In the current study, we used a GDM mouse model (through i.p. injection of a single dose of streptozocin, STZ, 60 mg/kg/bw) to investigate the biochemical and immunological changes in the blood and brain of diabetic mothers and their offspring relative to their appropriate controls. In addition, we estimated the expression levels of a set of microRNAs (miRNAs) to link between the dysregulation in the levels of miRNAs and the exposure to oxidative stress during embryonic development, as well as metabolic changes that occur after birth and during puberty in offspring (5-weeks-old). At the biochemical level, newborn pups appeared mostly to suffer from the same oxidative stress conditions of their mothers as shown by the significant increase in nitric oxide (NO) and malondialdehyde (MDA) in blood and brain of diabetic mothers and their pups. However, the 5-week-old offspring showed a significant increase in proinflammatory cytokines, IL-1β, IL-6, and TNF-α, and based on their blood glucose levels, could be considered as prediabetic (with glucose mean value of 165 mg/dl). In the meantime, the tested miRNAs, especially miR-15b, miR-146a, and miR-138 showed mostly similar expression levels in diabetic mothers and newborn pups. In this regard, miR-15a and -15b, miR-146a, and miR-138 are downregulated in diabetic mothers and their newborn pups relative to their appropriate controls. However, in offspring of diabetic mothers at puberty age, these miRNAs displayed different expression levels relative to mothers and control offspring. Interestingly, miR-193 and miR-763 expression levels were significantly lower in diabetic mothers but upregulated in their 5-week-old offspring, suggesting that miR-193 and miR-763 could be used as biomarkers to differentiate between prediabetes and diabetes.

Adipose and Plasma microRNAs miR-221 and 222 Associate with Obesity, Insulin Resistance, and New Onset Diabetes after Peritoneal Dialysis

BACKGROUND

The correlation between microRNA, obesity, and glycemic intolerance in patients on peritoneal dialysis (PD) is unknown. We aimed to measure the adipose and plasma miR-221 and -222 levels, and to evaluate their association with adiposity, glucose intolerance, and new onset diabetes mellitus (NODM) after the commencement of PD.

METHODS

We prospectively recruited incident adult PD patients. miR-221 and -222 were measured from adipose tissue and plasma obtained during PD catheter insertion. These patients were followed for 24 months, and the outcomes were changes in adiposity, insulin resistance, and NODM after PD.

RESULTS

One hundred and sixty-five patients were recruited. Patients with pre-existing DM had higher adipose miR-221 (1.1 ± 1.2 vs. 0.7 ± 0.9-fold, p = 0.02) and -222 (1.9 ± 2.0 vs. 1.2 ± 1.3-fold, p = 0.01). High adipose miR-221 and -222 levels were associated with a greater increase in waist circumference (miR-221: beta 1.82, 95% CI 0.57-3.07, p = 0.005; miR-222: beta 1.35, 95% CI 0.08-2.63, p = 0.038), Homeostatic Model Assessment for Insulin Resistance (HOMA) index (miR-221: beta 8.16, 95% CI 2.80-13.53, p = 0.003; miR-222: beta 6.59, 95% CI 1.13-12.05, p = 0.018), and insulin requirements (miR-221: beta 0.05, 95% CI 0.006-0.09, p = 0.02; miR-222: beta 0.06, 95% CI 0.02-0.11, p = 0.002) after PD. The plasma miR-222 level predicted the onset of NODM (OR 8.25, 95% CI 1.35-50.5, p = 0.02).

CONCLUSION

miR-221 and -222 are associated with the progression of obesity, insulin resistance, and NODM after PD.

Cardiovascular Disease-Associated MicroRNAs as Novel Biomarkers of First-Trimester Screening for Gestational Diabetes Mellitus in the Absence of Other Pregnancy-Related Complications

We assessed the diagnostic potential of cardiovascular disease-associated microRNAs for the early prediction of gestational diabetes mellitus (GDM) in singleton pregnancies of Caucasian descent in the absence of other pregnancy-related complications. Whole peripheral venous blood samples were collected within 10 to 13 weeks of gestation. This retrospective study involved all pregnancies diagnosed with only GDM (n = 121) and 80 normal term pregnancies selected with regard to equality of sample storage time. Gene expression of 29 microRNAs was assessed using real-time RT-PCR. Upregulation of 11 microRNAs (miR-1-3p, miR-20a-5p, miR-20b-5p, miR-23a-3p, miR-100-5p, miR-125b-5p, miR-126-3p, miR-181a-5p, miR-195-5p, miR-499a-5p, and miR-574-3p) was observed in pregnancies destinated to develop GDM. Combined screening of all 11 dysregulated microRNAs showed the highest accuracy for the early identification of pregnancies destinated to develop GDM. This screening identified 47.93% of GDM pregnancies at a 10.0% false positive rate (FPR). The predictive model for GDM based on aberrant microRNA expression profile was further improved via the implementation of clinical characteristics (maternal age and BMI at early stages of gestation and an infertility treatment by assisted reproductive technology). Following this, 69.17% of GDM pregnancies were identified at a 10.0% FPR. The effective prediction model specifically for severe GDM requiring administration of therapy involved using a combination of these three clinical characteristics and three microRNA biomarkers (miR-20a-5p, miR-20b-5p, and miR-195-5p). This model identified 78.95% of cases at a 10.0% FPR. The effective prediction model for GDM managed by diet only required the involvement of these three clinical characteristics and eight microRNA biomarkers (miR-1-3p, miR-20a-5p, miR-20b-5p, miR-100-5p, miR-125b-5p, miR-195-5p, miR-499a-5p, and miR-574-3p). With this, the model identified 50.50% of GDM pregnancies managed by diet only at a 10.0% FPR. When other clinical variables such as history of miscarriage, the presence of trombophilic gene mutations, positive first-trimester screening for preeclampsia and/or fetal growth restriction by the Fetal Medicine Foundation algorithm, and family history of diabetes mellitus in first-degree relatives were included in the GDM prediction model, the predictive power was further increased at a 10.0% FPR (72.50% GDM in total, 89.47% GDM requiring therapy, and 56.44% GDM managed by diet only). Cardiovascular disease-associated microRNAs represent promising early biomarkers to be implemented into routine first-trimester screening programs with a very good predictive potential for GDM.

Urinary Exosomal MicroRNAs as Biomarkers for Obesity-Associated Chronic Kidney Disease

The early detection of chronic kidney disease (CKD) is key to reducing the burden of disease and rising costs of care. This need has spurred interest in finding new biomarkers for CKD. Ideal bi-omarkers for CKD should be: easy to measure; stable; reliably detected, even when interfering substances are present; site-specific based on the type of injury (tubules vs. glomeruli); and its changes in concentration should correlate with disease risk or outcome. Currently, no single can-didate biomarker fulfills these criteria effectively, and the mechanisms underlying kidney fibrosis are not fully understood; however, there is growing evidence in support of microRNA-mediated pro-cesses. Specifically, urinary exosomal microRNAs may serve as biomarkers for kidney fibrosis. In-creasing incidences of obesity and the recognition of obesity-associated CKD have increased interest in the interplay of obesity and CKD. In this review, we provide: (1) an overview of the current scope of CKD biomarkers within obese individuals to elucidate the genetic pathways unique to obesi-ty-related CKD; (2) a review of microRNA expression in obese individuals with kidney fibrosis in the presence of comorbidities, such as diabetes mellitus and hypertension; (3) a review of thera-peutic processes, such as diet and exercise, that may influence miR-expression in obesity-associated CKD; (4) a review of the technical aspects of urinary exosome isolation; and (5) future areas of research.

A comprehensive overview on Micro RNA signature in type 2 diabetes Mellitus and its complications

MicroRNAs (miRNAs) are small endogenous, non-coding RNA molecules that can modulate the expression of their target genes. Since its discovery, an enormous breakthrough has been established regarding its biogenesis and pathophysiological action, which has revolutionized the field of molecular biology. In addition, recent studies have identified the existence of stable extracellular/circulating miRNAs tissues and in biological fluids like blood where they are safeguarded from endogenous ribonuclease activity. Type 2 diabetes mellitus (T2DM) has emerged as a prime health issue worldwide. Incidence has increased considerably over the past decade. There are various tests that have been employed to diagnose T2DM. But for early detection and development, the establishment of biomarkers are of paramount importance. Contemporary evidence also validates the signature of a set of this epigenetic factor miRNA in the development of various diseases, including T2DM. This article reviews the contemporary corroboration associating miRNAs and T2DM and emphasizes the potential role of miRNA as a circulatory biomarker that could alert the growing prevalence of T2DM. Also, it acknowledges the valuable compendium of information regarding biogenesis and functional role of circulating miRNA in insulin resistance which is intimately linked to T2DM.

The microRNA-29 family - role in metabolism and metabolic disease

The microRNA-29a family members miR-29a-3p, miR-29b-3p and miR-29c-3p are ubiquitously expressed and consistently increased in various tissues and cell types in conditions of metabolic disease; obesity, insulin resistance and type 2 diabetes. In pancreatic beta cells, miR-29a is required for normal exocytosis, but increased levels are associated with impaired beta cell function. Similarly, in liver miR-29 species are higher in models of insulin resistance and type 2 diabetes, and either knock-out or depletion using a microRNA inhibitor improves hepatic insulin resistance. In skeletal muscle, miR-29 upregulation is associated with insulin resistance and altered substrate oxidation, and similarly, in adipocytes over-expression of miR-29a leads to insulin resistance. Blocking miR-29a using nucleic acid antisense therapeutics show promising results in preclinical animal models of obesity and type 2 diabetes, although the widespread expression pattern of miR-29 family members complicates the exploration of single target tissues. However, in fibrotic diseases, such as in late complications of diabetes and metabolic disease (diabetic kidney disease, non-alcoholic steatohepatitis), miR-29 expression is suppressed by TGFβ allowing increased extracellular matrix collagen to form. In the clinical setting circulating levels of miR-29a and miR-29b are consistently increased in type 2 diabetes and in gestational diabetes, and are also possible prognostic markers for deterioration of glucose tolerance. In conclusion, miR-29 plays an essential role in various organs relevant to intermediary metabolism and its upregulation contribute to impaired glucose metabolism, while it suppresses fibrosis development. Thus, a correct balance of miR-29a levels seems important for cellular and organ homeostasis in metabolism.

Dietary Improvement during Lactation Normalizes miR-26a, miR-222 and miR-484 Levels in the Mammary Gland, but Not in Milk, of Diet-Induced Obese Rats

We aimed to evaluate in rats whether the levels of specific miRNA are altered in the mammary gland (MG) and milk of diet-induced obese dams, and whether improving maternal nutrition during lactation attenuates such alterations. Dams fed with a standard diet (SD) (control group), with a Western diet (WD) prior to and during gestation and lactation (WD group), or with WD prior to and during gestation but moved to SD during lactation (Rev group) were followed. The WD group showed higher miR-26a, miR-222 and miR-484 levels than the controls in the MG, but the miRNA profile in Rev animals was not different from those of the controls. The WD group also displayed higher miR-125a levels than the Rev group. Dams of the WD group, but not the Rev group, displayed lower mRNA expression levels of Rb1 (miR-26a’s target) and Elovl6 (miR-125a’s target) than the controls in the MG. The WD group also presented lower expression of Insig1 (miR-26a’s target) and Cxcr4 (miR-222’s target) than the Rev group. However, both WD and Rev animals displayed lower expression of Vegfa (miR-484’s target) than the controls. WD animals also showed greater miR-26a, miR-125a and miR-222 levels in the milk than the controls, but no differences were found between the WD and Rev groups. Thus, implementation of a healthy diet during lactation normalizes the expression levels of specific miRNAs and some target genes in the MG of diet-induced obese dams but not in milk.

Extracellular Vesicles and Their Emerging Roles as Cellular Messengers in Endocrinology: An Endocrine Society Scientific Statement

During the last decade, there has been great interest in elucidating the biological role of extracellular vesicles (EVs), particularly, their hormone-like role in cell-to-cell communication. The field of endocrinology is uniquely placed to provide insight into the functions of EVs, which are secreted from all cells into biological fluids and carry endocrine signals to engage in paracellular and distal interactions. EVs are a heterogeneous population of membrane-bound vesicles of varying size, content, and bioactivity. EVs are specifically packaged with signaling molecules, including lipids, proteins, and nucleic acids, and are released via exocytosis into biofluid compartments. EVs regulate the activity of both proximal and distal target cells, including translational activity, metabolism, growth, and development. As such, EVs signaling represents an integral pathway mediating intercellular communication. Moreover, as the content of EVs is cell-type specific, it is a "fingerprint" of the releasing cell and its metabolic status. Recently, changes in the profile of EV and bioactivity have been described in several endocrine-related conditions including diabetes, obesity, cardiovascular diseases, and cancer. The goal of this statement is to highlight relevant aspects of EV research and their potential role in the field of endocrinology.

Insight into the Role of the PI3K/Akt Pathway in Ischemic Injury and Post-Infarct Left Ventricular Remodeling in Normal and Diabetic Heart

Despite the significant decline in mortality, cardiovascular diseases are still the leading cause of death worldwide. Among them, myocardial infarction (MI) seems to be the most important. A further decline in the death rate may be achieved by the introduction of molecularly targeted drugs. It seems that the components of the PI3K/Akt signaling pathway are good candidates for this. The PI3K/Akt pathway plays a key role in the regulation of the growth and survival of cells, such as cardiomyocytes. In addition, it has been shown that the activation of the PI3K/Akt pathway results in the alleviation of the negative post-infarct changes in the myocardium and is impaired in the state of diabetes. In this article, the role of this pathway was described in each step of ischemia and subsequent left ventricular remodeling. In addition, we point out the most promising substances which need more investigation before introduction into clinical practice. Moreover, we present the impact of diabetes and widely used cardiac and antidiabetic drugs on the PI3K/Akt pathway and discuss the molecular mechanism of its effects on myocardial ischemia and left ventricular remodeling.

Serum microRNA panels predict bariatric surgery outcomes

OBJECTIVE

The weight losses after bariatric surgery are modulated by multiple factors in people with obesity. MicroRNAs (miRNAs) have been reported to show significant regulatory roles in adipose tissue. However, a serum miRNA signature to serve as a biomarker of sustained weight losses following bariatric surgery has not yet been established.

METHODS

MiRNA microarray was used to identify differentially expressed miRNAs in the serum of patients with an effective response after bariatric surgery compared with those without. Excess weight loss > 55% at 6 months after surgery was defined as an effective response.

RESULTS

Three miRNAs were shown to have a significantly differential expression between patients with or without an effective response following bariatric surgery. The miR-31-5p was downregulated, whereas miR-328-3p and miR-181a-5p were upregulated in the patients with effective responses compared with those without effective responses. Panels of the serum ratios of miR-328-3p/miR-31-5p or miR-181a-5p/miR-31-5p and individual BMI value exhibited good performance in preoperative prediction of treatment effectiveness. Bioinformatic analysis depicted that predicted targets of these miRNAs were involved in the regulation of the AMP-activated protein kinase signaling pathway.

CONCLUSIONS

A circulating miRNA signature with clinical variables (BMI) can be a clinical biomarker to predict effectiveness following bariatric surgery.

Transcriptome of visceral adipose tissue identifies an inflammation-related ceRNA network that regulates obesity

Obesity is becoming an epidemic of widespread concern, but the underlying causes remain elusive. In this study, whole transcriptome RNA sequencing revealed differential profiles of noncoding (nc) RNAs and mRNAs in visceral adipose tissue from obese (BMI > 32.5 kg/m²) and lean (BMI < 20 kg/m²) individuals, with 1920 differentially expressed genes, 1466 long noncoding (lnc) RNAs, 122 micro (mi) RNAs, and 52 circular (circ) RNAs identified. Gene Set Enrichment Analysis, Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis revealed that these ncRNAs were involved in inflammation-related pathways that included cytokine-cytokine receptor interaction, the tumor necrosis factor and nuclear factor kappa B signaling pathways. The results indicated a critical role of inflammation in the pathogenesis of obesity. The network interaction of lncRNA, circRNA, and miRNA revealed a competing endogenous (ce) RNA network that was associated with inflammation. The ceRNA network included circORC5/miR-197-5p/TNFRSF10D and circNTRK2/miR-760/LAT, which were dysregulated in obese patients. In conclusion, this whole transcriptome study provided a pool of data that will be useful for identifying biomarkers of obesity and identified an obesity-associated ceRNA network that is regulated by circORC5 and circNTRK2.

Adipocyte-Specific Inhibition of Mir221/222 Ameliorates Diet-Induced Obesity Through Targeting Ddit4

MicroRNAs expressed in adipocytes are involved in transcriptional regulation of target mRNAs in obesity, but miRNAs critically involved in this process is not well characterized. Here, we identified upregulation of miR-221-3p and miR-222-3p in the white adipose tissues in C57BL/6 mice fed with high fat-high sucrose (HFHS) chow by RNA sequencing. Mir221 and Mir222 are paralogous genes and share the common seed sequence and Mir221/222AdipoKO mice fed with HFHS chow demonstrated resistance to the development of obesity compared with Mir221/222flox/y . Ddit4 is a direct target of Mir221 and Mir222, and the upregulation of Ddit4 in Mir221/222AdipoKO was associated with the suppression of TSC2 (tuberous sclerosis complex 2)/mammalian target of rapamycin complex 1 (mTORC1)/S6K (ribosomal protein S6 kinase) pathway. The overexpression of miR-222-3p linked to enhanced adipogenesis, and it may be a potential candidate for miRNA-based therapy.

Hypothalamic miR-1983 Targets Insulin Receptor β and the Insulin-mediated miR-1983 Increase Is Blocked by Metformin

MicroRNAs (miRNAs) expressed in the hypothalamus are capable of regulating energy balance and peripheral metabolism by inhibiting translation of target messenger RNAs (mRNAs). Hypothalamic insulin resistance is known to precede that in the periphery, thus a critical unanswered question is whether central insulin resistance creates a specific hypothalamic miRNA signature that can be identified and targeted. Here we show that miR-1983, a unique miRNA, is upregulated in vitro in 2 insulin-resistant immortalized hypothalamic neuronal neuropeptide Y-expressing models, and in vivo in hyperinsulinemic mice, with a concomitant decrease of insulin receptor β subunit protein, a target of miR-1983. Importantly, we demonstrate that miR-1983 is detectable in human blood serum and that its levels significantly correlate with blood insulin and the homeostatic model assessment of insulin resistance. Levels of miR-1983 are normalized with metformin exposure in mouse hypothalamic neuronal cell culture. Our findings provide evidence for miR-1983 as a unique biomarker of cellular insulin resistance, and a potential therapeutic target for prevention of human metabolic disease.

Systematic review of transcriptome and microRNAome associations with gestational diabetes mellitus

PURPOSE

Gestational diabetes (GDM) is associated with increased risk for preterm birth and related complications for both the pregnant person and newborn. Changes in gene expression have the potential to characterize complex interactions between genetic and behavioral/environmental risk factors for GDM. Our goal was to summarize the state of the science about changes in gene expression and GDM.

DESIGN

The systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

METHODS

PubMed articles about humans, in English, from any date were included if they described mRNA transcriptome or microRNA findings from blood samples in adults with GDM compared with adults without GDM.

RESULTS

Sixteen articles were found representing 1355 adults (n=674 with GDM, n=681 controls) from 12 countries. Three studies reported transcriptome results and thirteen reported microRNA findings. Identified pathways described various aspects of diabetes pathogenesis, including glucose and insulin signaling, regulation, and transport; natural killer cell mediated cytotoxicity; and fatty acid biosynthesis and metabolism. Studies described 135 unique miRNAs that were associated with GDM, of which eight (miR-16-5p, miR-17-5p, miR-20a-5p, miR-29a-3p, miR-195-5p, miR-222-3p, miR-210-3p, and miR-342-3p) were described in 2 or more studies. Findings suggest that miRNA levels vary based on the time in pregnancy when GDM develops, the time point at which they were measured, sex assigned at birth of the offspring, and both the pre-pregnancy and gestational body mass index of the pregnant person.

CONCLUSIONS

The mRNA, miRNA, gene targets, and pathways identified in this review contribute to our understanding of GDM pathogenesis; however, further research is warranted to validate previous findings. In particular, longitudinal repeated-measures designs are needed that control for participant characteristics (e.g., weight), use standardized data collection methods and analysis tools, and are sufficiently powered to detect differences between subgroups. Findings may be used to improve early diagnosis, prevention, medication choice and/or clinical treatment of patients with GDM.

MiRNA and associated inflammatory changes from baseline to hypoglycemia in type 2 diabetes

OBJECTIVE

Hypoglycemia in type 2 diabetes (T2D) increases morbidity and mortality but the underlying physiological response is still not fully understood, though physiological changes are still apparent 24 hours after the event. Small noncoding microRNA (miRNA) have multiple downstream biological effects that may respond rapidly to stress. We hypothesized that hypoglycemia would induce rapid miRNA changes; therefore, this pilot exploratory study was undertaken.

METHODS

A pilot prospective, parallel study in T2D (n=23) and controls (n=23). Insulin-induced hypoglycemia (2mmol/l: 36mg/dl) was induced and blood sampling performed at baseline and hypoglycemia. Initial profiling of miRNA was undertaken on pooled samples identified 96 miRNA that were differentially regulated, followed by validation on a custom designed 112 miRNA panel.

RESULTS

Nine miRNAs differed from baseline to hypoglycemia in control subjects; eight were upregulated: miR-1303, miR-let-7e-5p, miR-1267, miR-30a-5p, miR-571, miR-661, miR-770-5p, miR-892b and one was downregulated: miR-652-3p. None of the miRNAs differed from baseline in T2D subjects.

CONCLUSION

A rapid miRNA response reflecting protective pathways was seen in control subjects that appeared to be lost in T2D, suggesting that mitigating responses to hypoglycemia with blunting of the counter-regulatory response in T2D occurs even in patients with short duration of disease.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03102801?term=NCT03102801&draw=2&rank=1, identifier NCT03102801.

Impact of the Main Cardiovascular Risk Factors on Plasma Extracellular Vesicles and Their Influence on the Heart's Vulnerability to Ischemia-Reperfusion Injury

The majority of cardiovascular deaths are associated with acute coronary syndrome, especially ST-elevation myocardial infarction. Therapeutic reperfusion alone can contribute up to 40 percent of total infarct size following coronary artery occlusion, which is called ischemia-reperfusion injury (IRI). Its size depends on many factors, including the main risk factors of cardiovascular mortality, such as age, sex, systolic blood pressure, smoking, and total cholesterol level as well as obesity, diabetes, and physical effort. Extracellular vesicles (EVs) are membrane-coated particles released by every type of cell, which can carry content that affects the functioning of other tissues. Their role is essential in the communication between healthy and dysfunctional cells. In this article, data on the variability of the content of EVs in patients with the most prevalent cardiovascular risk factors is presented, and their influence on IRI is discussed.

Screening of MicroRNAs with Potential Systemic Effects Released from Goose Fatty Liver

Communication between tissues and organs plays an important role in the maintenance of normal physiological functions as well as the occurrence and development of diseases. Communication molecules act as a bridge for interactions between tissues and organs, playing not only a local role in the tissues and organs where they are secreted but also in exerting systemic effects on the whole body via circulation. In this study, blood microRNA-omics analysis of overfed vs. normally fed (control) Landes geese revealed that the content of each of the 21 microRNAs (miRNAs) in the blood of overfed geese was significantly higher than that in the blood of control geese. These miRNAs may have systematic effects in the development of goose fatty liver as well as being candidate markers for the diagnosis of goose fatty liver. We determined the expression of miR-143, miR-455-5p, miR-222a-5p, miR-184, miR-1662, and miR-129-5p using quantitative PCR in goose fatty liver vs. that in normal liver. The expression of these miRNAs, except miR-129-5p, in goose fatty liver was also significantly higher than that in normal liver (P<0.05), suggesting that these blood miRNAs are released from goose fatty liver. In addition, we found that expression of IGFBP5, the predicted target gene of miR-143, was significantly decreased in goose fatty liver vs. the normal liver (P<0.05), indicating that miR-143 may exert both local and systematic effects by inhibiting the expression of IGFBP5, thus promoting the development of goose fatty liver. In conclusion, we identified several miRNAs, including those we validated (i.e., miR-143, miR-455-5p, miR-222a-5p, miR-184, miR-1662, and miR-129-5p) that may serve as candidate markers in the diagnosis of goose fatty liver as well as local and global regulators contributing to the development of goose fatty liver.

Exosomes as mediators of intercellular crosstalk in metabolism

Exosomes are nanoparticles secreted by all cell types and are a large component of the broader class of nanoparticles termed extracellular vesicles (EVs). Once secreted, exosomes gain access to the interstitial space and ultimately the circulation, where they exert local paracrine or distal systemic effects. Because of this, exosomes are important components of an intercellular and intraorgan communication system capable of carrying biologic signals from one cell type or tissue to another. The exosomal cargo consists of proteins, lipids, miRNAs, and other RNA species, and many of the biologic effects of exosomes have been attributed to miRNAs. Exosomal miRNAs have also been used as disease biomarkers. The field of exosome biology and metabolism is rapidly expanding, with new discoveries and reports appearing on a regular basis, and it is possible that potential therapeutic approaches for the use of exosomes or miRNAs in metabolic diseases will be initiated in the near future.

Extracellular miRNAs in redox signaling: Health, disease and potential therapies

Extracellular microRNAs (miRNAs) have emerged as important mediators of cell-to-cell communication and intertissue crosstalk. MiRNAs are produced by virtually all types of eukaryotic cells and can be selectively packaged and released to the extracellular medium, where they may reach distal cells to regulate gene expression cell non-autonomously. By doing so, miRNAs participate in integrative physiology. Oxidative stress affects miRNA expression, while miRNAs control redox signaling. Disruption in miRNA expression, processing or release to the extracellular compartment are associated with aging and a number of chronic diseases, such as obesity, type 2 diabetes, neurodegenerative diseases and cancer, all of them being conditions related to oxidative stress. Here we discuss the interplay between redox balance and miRNA function and secretion as a determinant of health and disease states, reviewing the findings that support this notion and highlighting novel and yet understudied venues of research in the field.

Relationship between Functional miR-143/145 Cluster Variants and Susceptibility to Type 2 Diabetes Mellitus: A Preliminary Case-Control Study and Bioinformatics Analyses

Purpose: To investigate the link between two variants (rs4705342 and rs4705343) in the promoter of the miR-143/145 cluster with Type 2 diabetes mellitus (T2DM) risk. Methods:A total of 1200 subjects were genotyped using the ARMS-PCR method. Results: The rs4705342 variant enhanced the risk of T2DM under codominant CC (OR = 3.24; 95% CI: 1.89-5.60), recessive TT+TC (OR = 3.02; 95% CI: 1.77-5.17), and dominant TC+CC (OR = 1.35; 95% CI: 1.08-1.71) genetic models. Individuals carrying the C allele of rs4705342 conferred a 1.43 fold increased risk of T2DM. As regards rs4705343, decreased risk of T2DM was observed under codominant TC (OR = 0.53; 95% CI: 0.42-0.67), over-dominant TT+CC (OR = 0.51; 95% CI: 0.40-0.64), and dominant TC+CC (OR = 0.59; 95% CI: 0.48-0.75) models. Haplotype analysis of the variants showed a 1.941-fold increased risk of T2DM regarding the C T combination. Significant associations were noticed between different haplotypes and lipid indices of T2DM patients. There were no notable changes in p-values after adjustment for BMI. Computational analysis revealed that miR143 and/or miR145 target important genes involved in glucose and lipid metabolism. Conclusions: Functional miR-143/145 variants might influence the risk of T2DM. Hence, clarifying the precise regulatory mechanisms of gene expression in the development of T2DM will significantly guide researchers to find a novel target for therapeutic intervention.

Recent Developments in Delivery of MicroRNAs Utilizing Nanosystems for Metabolic Syndrome Therapy

Metabolic syndrome (MetS) is a set of complex, chronic inflammatory conditions that are characterized by central obesity and associated with an increased risk of cardiovascular diseases. In recent years, microRNAs (miRNAs) have become an important type of endocrine factors, which play crucial roles in maintaining energy balance and metabolic homeostasis. However, its unfavorable properties such as easy degradation in blood and off-target effect are still a barrier for clinical application. Nanosystem based delivery possess strong protection, high bioavailability and control release rate, which is beneficial for success of gene therapy. This review first describes the current progress and advances on miRNAs associated with MetS, then provides a summary of the therapeutic potential and targets of miRNAs in metabolic organs. Next, it discusses recent advances in the functionalized development of classic delivery systems (exosomes, liposomes and polymers), including their structures, properties, functions and applications. Furthermore, this work briefly discusses the intelligent strategies used in emerging novel delivery systems (selenium nanoparticles, DNA origami, microneedles and magnetosomes). Finally, challenges and future directions in this field are discussed provide a comprehensive overview of the future development of targeted miRNAs delivery for MetS treatment. With these contributions, it is expected to address and accelerate the development of effective NA delivery systems for the treatment of MetS.

MicroRNA biomarkers of type 2 diabetes: A protocol for corroborating evidence by computational genomics and meta-analyses

Background

Few microRNAs were found consistently dysregulated in type 2 diabetes (T2D) that would gain confidence from Big Pharma to develop diagnostic or therapeutic biomarkers. This study aimed to corroborate evidence from eligible microRNAs-T2D association studies according to stringent quality criteria covering both biological and statistical significance in T2D for biomarker development.

Methods and analyses

Controlled microRNA expression profiling studies on human with T2D will be retrieved from PubMed, ScienceDirect, and Embase for selecting the statistically significant microRNAs according to pre-specified search strategies and inclusion criteria. Multiple meta-analyses with restricted maximum-likelihood estimation and empirical Bayes estimation under the random-effects model will be conducted by metafor package in R. Subgroup and sensitivity analyses further examine the microRNA candidates for their disease specificity, tissue specificity, blood fraction specificity, and statistical robustness of evidence. Biologically relevant microRNAs will then be selected through genomic database corroboration. Their association with T2D is further measured by area under the curve (AUC) of receive operating characteristic (ROC). Meta-analysis of AUC of potential biomarkers will also be conducted. Enrichment analysis on potential microRNA biomarkers and their target genes will be performed by iPathwayGuide and clusterProfiler, respectively. The corresponding reporting guidelines will be used to assess the quality of included studies according to their profiling methods (microarray, RT-PCR, and RNA-Seq).

Ethics and dissemination

No ethics approval is required since this study does not include identifiable personal patient data.

Protocol registration number

CRD42017081659.

Association Between miR-148a and DNA Methylation Profile in Individuals Exposed to Lead (Pb)

Experimental and epidemiologic studies have shown that lead (Pb) is able to induce epigenetic modifications, such as changes in DNA methylation profiles, in chromatin remodeling, as well as the expression of non-coding RNAs (ncRNAs). However, very little is known about the interactions between microRNAs (miRNAs) expression and DNA methylation status in individuals exposed to the metal. The aim of the present study was to investigate the impact of hsa-miR-148a expression on DNA methylation status, in 85 workers exposed to Pb. Blood and plasma lead levels (BLL and PLL, respectively) were determined by ICP-MS; expression of the miRNA-148a was quantified by RT-qPCR (TaqMan assay) and assessment of the global DNA methylation profile (by measurement of 5-methylcytosine; % 5-mC) was performed by ELISA. An inverse association was seen between miR-148a and % 5-mC DNA, as a function of BLL and PLL (β = −3.7; p = 0.071 and β = −4.1; p = 0.049, respectively) adjusted for age, BMI, smoking, and alcohol consumption. Taken together, our study provides further evidence concerning the interactions between DNA methylation profile and miR-148a, in individuals exposed to Pb.

miR-140-5p Aggravates Insulin Resistance via Directly Targeting GYS1 and PPP1CC in Insulin-Resistant HepG2 Cells

BACKGROUND

Much attention has been paid to the regulatory role of microRNA (miRNA) in insulin resistance. Nevertheless, how miR-140-5p regulates insulin resistance remains unclear. In this research, we aim to investigate the roles of miR-140-5p in insulin resistance.

METHODS

qRT-PCR is used to analyze the expression level of miR-140-5p in insulin-resistant HepG2 cells. Glucose consumption and glucose uptake are detected to study the effect of miR-140-5p knockdown in insulin-resistant HepG2 cells and miR-140-5p overexpression in HepG2 cells. Bioinformatic analysis, luciferase reporter assay and confirmatory experiments are applied to identify the target gene bound with miR-140-5p and study the effect of miR-140-5p on the downstream substrates of target genes. Rescue experiments have verified the roles of miR-140-5p and target gene in glucose metabolism.

RESULTS

The expression level of miR-140-5p was upregulated in insulin-resistant HepG2 cells and was significantly correlated with cellular glucose metabolism. Functionally, miR-140-5p overexpression induced impairment of glucose consumption and glucose uptake. Besides, bioinformatics analysis indicated that glycogen synthetase (GYS1) and protein phosphatase 1 catalytic subunit gamma (PPP1CC) were the target genes of miR-140-5p. Western blotting and qRT-PCR results revealed a negative correlation between GYS1, PPP1CC and miR-140-5p. The glycogen detection results showed that miR140-5p inhibited the production of the downstream substrates of the target gene. Rescue experiments showed that inhibition of GYS1 or PPP1CC partially enhanced the insulin-resistant effects of miR-140-5p knockdown in insulin-resistant HepG2 cells.

CONCLUSION

miR-140-5p overexpression augments the development of insulin resistance and miR-140-5p may be served as a therapeutic target of metabolic diseases.

Cell-free DNA and RNA-measurement and applications in clinical diagnostics with focus on metabolic disorders

Circulating cell-free DNA (cfDNA) and RNA (cfRNA) hold enormous potential as a new class of biomarkers for the development of noninvasive liquid biopsies in many diseases and conditions. In recent years, cfDNA and cfRNA have been studied intensely as tools for noninvasive prenatal testing, solid organ transplantation, cancer screening, and monitoring of tumors. In obesity, higher cfDNA concentration indicates accelerated cellular turnover of adipocytes during expansion of adipose mass and may be directly involved in the development of adipose tissue insulin resistance by inducing inflammation. Furthermore, cfDNA and cfRNA have promising diagnostic value in a range of obesity-related metabolic disorders, such as nonalcoholic fatty liver disease, type 2 diabetes, and diabetic complications. Here, we review the current and future applications of cfDNA and cfRNA within clinical diagnostics, discuss technical and analytical challenges in the field, and summarize the opportunities of using cfDNA and cfRNA in the diagnostics and prognostics of obesity-related metabolic disorders.

Comprehensive Analysis Reveals Novel Interactions between Circulating MicroRNAs and Gut Microbiota Composition in Human Obesity

Background: The determinants that mediate the interactions between microRNAs and the gut microbiome impacting on obesity are scarcely understood. Thus, the aim of this study was to investigate possible interactions between circulating microRNAs and gut microbiota composition in obesity. Method: The sample comprised 78 subjects with obesity (cases, body mass index (BMI): 30–40 kg/m²) and 25 eutrophic individuals (controls, BMI ≤ 25 kg/m²). The expression of 96 microRNAs was investigated in plasma of all individuals using miRCURY LNA miRNA Custom PCR Panels. Bacterial DNA sequencing was performed following the Illumina 16S protocol. The FDR correction was used for multiple comparison analyses. Results: A total of 26 circulating microRNAs and 12 bacterial species were found differentially expressed between cases and controls. Interestingly, an interaction among three miRNAs (miR-130b-3p, miR-185-5p and miR-21-5p) with Bacteroides eggerthi and BMI levels was evidenced (r² = 0.148, p = 0.004). Moreover, these microRNAs regulate genes that participate in metabolism-related pathways, including fatty acid degradation, insulin signaling and glycerolipid metabolism. Conclusions: This study characterized an interaction between the abundance of 4 bacterial species and 14 circulating microRNAs in relation to obesity. Moreover, the current study also suggests that miRNAs may serve as a communication mechanism between the gut microbiome and human hosts.

The Cell Type-Specific Functions of miR-21 in Cardiovascular Diseases

Cardiovascular diseases are one of the prime reasons for disability and death worldwide. Diseases and conditions, such as hypoxia, pressure overload, infection, and hyperglycemia, might initiate cardiac remodeling and dysfunction by inducing hypertrophy or apoptosis in cardiomyocytes and by promoting proliferation in cardiac fibroblasts. In the vascular system, injuries decrease the endothelial nitric oxide levels and affect the phenotype of vascular smooth muscle cells. Understanding the underlying mechanisms will be helpful for the development of a precise therapeutic approach. Various microRNAs are involved in mediating multiple pathological and physiological processes in the heart. A cardiac enriched microRNA, miR-21, which is essential for cardiac homeostasis, has been demonstrated to act as a cell–cell messenger with diverse functions. This review describes the cell type–specific functions of miR-21 in different cardiovascular diseases and its prospects in clinical therapy.

Regulatory microRNAs in Brown, Brite and White Adipose Tissue

MicroRNAs (miRNAs) constitute a class of short noncoding RNAs which regulate gene expression by targeting messenger RNA, inducing translational repression and messenger RNA degradation. This regulation of gene expression by miRNAs in adipose tissue (AT) can impact on the regulation of metabolism and energy homeostasis, particularly considering the different types of adipocytes which exist in mammals, i.e., white adipocytes (white AT; WAT), brown adipocytes (brown AT; BAT), and inducible brown adipocytes in WAT (beige or brite or brown-in-white adipocytes). Indeed, an increasing number of miRNAs has been identified to regulate key signaling pathways of adipogenesis in BAT, brite AT, and WAT by acting on transcription factors that promote or inhibit adipocyte differentiation. For example, MiR-328, MiR-378, MiR-30b/c, MiR-455, MiR-32, and MiR-193b-365 activate brown adipogenesis, whereas MiR-34a, MiR-133, MiR-155, and MiR-27b are brown adipogenesis inhibitors. Given that WAT mainly stores energy as lipids, whilst BAT mainly dissipates energy as heat, clarifying the effects of miRNAs in different types of AT has recently attracted significant research interest, aiming to also develop novel miRNA-based therapies against obesity, diabetes, and other obesity-related diseases. Therefore, this review presents an up-to-date comprehensive overview of the role of key regulatory miRNAs in BAT, brite AT, and WAT.

microRNA exchange via extracellular vesicles in cancer

Cells utilize different means of inter-cellular communication to function properly. Here, we review the crosstalk between cancer cells and their surrounding environment through microRNA (miRNA)-containing extracellular vesicles (EVs). The current findings suggest that the export of miRNAs and uptake of miRNA-containing EVs might be an active process. As post-transcriptional regulators of gene expression, cancer-derived miRNAs that are taken up by normal cells can change the translational profile of the recipient cell towards a transformed proteome. Stromal cells can also deliver miRNAs via EVs to cancer cells to support tumour growth and cancer progression. Therefore, gaining a better understanding of EV-mediated inter-cellular communication in the tumour microenvironment might lead to the development of novel diagnostic and therapeutic strategies.

The Role of microRNAs in Metabolic Syndrome-Related Oxidative Stress

Oxidative stress (OxS) is the cause and the consequence of metabolic syndrome (MetS), the incidence and economic burden of which is increasing each year. OxS triggers the dysregulation of signaling pathways associated with metabolism and epigenetics, including microRNAs, which are biomarkers of metabolic disorders. In this review, we aimed to summarize the current knowledge regarding the interplay between microRNAs and OxS in MetS and its components. We searched PubMed and Google Scholar to summarize the most relevant studies. Collected data suggested that different sources of OxS (e.g., hyperglycemia, insulin resistance (IR), hyperlipidemia, obesity, proinflammatory cytokines) change the expression of numerous microRNAs in organs involved in the regulation of glucose and lipid metabolism and endothelium. Dysregulated microRNAs either directly or indirectly affect the expression and/or activity of molecules of antioxidative signaling pathways (SIRT1, FOXOs, Keap1/Nrf2) along with effector enzymes (e.g., GPx-1, SOD1/2, HO-1), ROS producers (e.g., NOX4/5), as well as genes of numerous signaling pathways connected with inflammation, insulin sensitivity, and lipid metabolism, thus promoting the progression of metabolic imbalance. MicroRNAs appear to be important epigenetic modifiers in managing the delicate redox balance, mediating either pro- or antioxidant biological impacts. Summarizing, microRNAs may be promising therapeutic targets in ameliorating the repercussions of OxS in MetS.

Early-Onset Diabetes as Risk Factor for Pancreatic Cancer: miRNA Expression Profiling in Plasma Uncovers a Role for miR-20b-5p, miR-29a, and miR-18a-5p in Diabetes of Recent Diagnosis

The high prevalence of early-diabetes in patients with pancreatic cancer (PanC) implies that its recognition could help identify people at high risk of developing PanC. Candidate microRNAs (miRNAs) associated with recent diabetes were screened from our previous miRNA expression profiling on 10 pools of plasma from PanC patients and non-PanC controls, both including also subjects with early- and late-diabetes. The droplet digital PCR (ddPCR) was used to re-test candidate miRNAs in a new independent cohort of 69 subjects (40 PanC, 29 non-PanC) with early- (17 PanC, 13 non-PanC) or late-diabetes (23 PanC, 16 non-PanC), and in 100 non-diabetic healthy subjects (HS). miRNA levels were evaluated for differences between subjects enrolled into the study and for their diagnostic performance, also compared to the CA 19-9 determinations. MiR-20b-5p, miR-29a, and miR-18a-5p were selected from the previous miRNA expression profiling. The ddPCR confirmed the increase of miR-20b-5p and miR-29a levels in PanC with early- compared to those with late-diabetes. Conversely, miR-20b-5p, miR-29a, and miR-18a-5p were over-expressed in both PanC and non-PanC with recent diabetes compared to HS, and each miRNA achieved a similar diagnostic performance in distinguishing either PanC or non-PanC with early-diabetes from HS (miR-20b-5p: AUC = 0.877 vs. AUC = 0.873; miR-29a: AUC = 0.838 vs. AUC = 0.810; miR-18a-5p: AUC = 0.824 vs. AUC = 0.875). Despite miR-20b-5p and miR-29a expressions were also higher both in PanC and non-PanC with late-diabetes with respect to HS, the diagnostic accuracy in PanC with late-diabetes vs. HS reached by each miRNA (miR-20b-5p: AUC = 0.760; miR-29a: AUC = 0.630) was lower than the ones achieved in PanC with early-diabetes vs. HS. Furthermore, miR-20b-5p achieved a higher diagnostic accuracy to discriminate non-PanC with early-diabetes from HS (AUC = 0.868; SP = 81%; PPV = 32.1%) compared to the CA 19-9 (AUC = 0.700; SP = 40.0%; PPV = 15.5%), and the joint (miR-20b-5p and CA 19-9) discrimination ability was higher than the one achieved by the CA 19-9 tested alone (AUC = 0.900, p = 0.003). Our data highlighted the association between miR-18a-5p and early-diabetes, and suggested for miR-20b-5p and miR-29 a role in identifying early diabetes in PanC, albeit not as an early manifestation of cancer. MiR-20b-5p as more informative marker than CA 19-9 in distinguishing non-PanC with recent diabetes from HS was also uncovered.

Lowered Expression of MicroRNAs 221 and 222 Mediate Apoptosis Induced by High Glucose in Human Periodontal Ligament Cells

Impaired periodontal healing is a common complication of diabetes mellitus (DM), frequently related to hyperglycemia. MicroRNAs 221 and 222 have been studied as biomarkers for inflammatory diseases, including diabetes, but their role in the periodontal ligament (PL) is unknown. The effects of high glucose on human PL cells death were studied, as well as the expression of microRNA-221 and microRNA-222, potentially modulated by DM. Cells were obtained from the premolar teeth of young humans and cultured for 7 days under different glucose concentrations (5 or 30 mM). MicroRNAs-221/222 expressions were evaluated by real-time RT-PCR and apoptosis by TUNEL assays. Caspase-3 expression was studied by western blotting and immunocytochemistry. High glucose increased apoptosis and caspase-3 protein expression by about 3×. MicroRNA-221 and microRNA-222 expressions decreased by nearly 40% under high glucose. MicroRNA-221 and microRNA-222 inhibition using antagomiRs increased apoptosis by 2-3×, while the expression of caspase-3, a validated target for these microRNAs, was increased by 50%. The overexpression of both microRNAs using miR mimics in high glucose cells did no effect on apoptosis but increased caspase-3 expression by 30%. In conclusion, high glucose induces apoptosis of human PL cells potentially through a reduction of microRNA-221 and microRNA-222 expression and elevation of caspase-3.

Substantially Altered Expression Profile of Diabetes/Cardiovascular/Cerebrovascular Disease Associated microRNAs in Children Descending from Pregnancy Complicated by Gestational Diabetes Mellitus-One of Several Possible Reasons for an Increased Cardiovascular Risk

Gestational diabetes mellitus (GDM), one of the major pregnancy-related complications, characterized as a transitory form of diabetes induced by insulin resistance accompanied by a low/absent pancreatic beta-cell compensatory adaptation to the increased insulin demand, causes the acute, long-term, and transgenerational health complications. The aim of the study was to assess if alterations in gene expression of microRNAs associated with diabetes/cardiovascular/cerebrovascular diseases are present in whole peripheral blood of children aged 3-11 years descending from GDM complicated pregnancies. A substantially altered microRNA expression profile was found in children descending from GDM complicated pregnancies. Almost all microRNAs with the exception of miR-92a-3p, miR-155-5p, and miR-210-3p were upregulated. The microRNA expression profile also differed between children after normal and GDM complicated pregnancies in relation to the presence of overweight/obesity, prehypertension/hypertension, and/or valve problems and heart defects. Always, screening based on the combination of microRNAs was superior over using individual microRNAs, since at 10.0% false positive rate it was able to identify a large proportion of children with an aberrant microRNA expression profile (88.14% regardless of clinical findings, 75.41% with normal clinical findings, and 96.49% with abnormal clinical findings). In addition, the higher incidence of valve problems and heart defects was found in children with a prior exposure to GDM. The extensive file of predicted targets of all microRNAs aberrantly expressed in children descending from GDM complicated pregnancies indicates that a large group of these genes is involved in ontologies of diabetes/cardiovascular/cerebrovascular diseases. In general, children with a prior exposure to GDM are at higher risk of later development of diabetes mellitus and cardiovascular/cerebrovascular diseases, and would benefit from dispensarisation as well as implementation of primary prevention strategies.

Altered adipose tissue and adipocyte function in the pathogenesis of metabolic syndrome

Over the past decade, great progress has been made in understanding the complexity of adipose tissue biology and its role in metabolism. This includes new insights into the multiple layers of adipose tissue heterogeneity, not only differences between white and brown adipocytes, but also differences in white adipose tissue at the depot level and even heterogeneity of white adipocytes within a single depot. These inter- and intra-depot differences in adipocytes are developmentally programmed and contribute to the wide range of effects observed in disorders with fat excess (overweight/obesity) or fat loss (lipodystrophy). Recent studies also highlight the underappreciated dynamic nature of adipose tissue, including potential to undergo rapid turnover and dedifferentiation and as a source of stem cells. Finally, we explore the rapidly expanding field of adipose tissue as an endocrine organ, and how adipose tissue communicates with other tissues to regulate systemic metabolism both centrally and peripherally through secretion of adipocyte-derived peptide hormones, inflammatory mediators, signaling lipids, and miRNAs packaged in exosomes. Together these attributes and complexities create a robust, multidimensional signaling network that is central to metabolic homeostasis.

[MicroRNA and obesity. A modern view of the problem (review of literature).]

The incidence of obesity is steadily increasing worldwide, reaching the epidemic. Obesity is associated with cardiometabolic diseases through the complex interactions between genetics and epigenetics predisposition, the environment, diet, and lifestyle. However, the molecular mechanisms and factors influencing these processes are not fully known. MicroRNAs are a new class of important regulatory determinants in many biological and pathological processes. There is increasing evidence of the role of miRNAs in the regulation of the functional activity of adipose tissue and the development of obesity. A change in the expression of MicroRNAs can lead to changes in the activity of genes that control a number of biological processes, including inflammation, lipid metabolism, and adipogenesis. Understanding the role of miRNAs in the regulation of adipogenesis and the development of obesity will establish therapeutic targets for the development of new and effective drugs, which will lead to a breakthrough in the fight against obesity and related diseases. This review presents current data on the role of miRNAs in the regulation of the functional activity of adipose tissue, including adipogenesis of white, beige and brown adipocytes, as well as the prerequisites for using miRNAs as biomarkers of obesity and the possibility of therapeutic use.

Elevated Plasma Levels of Circulating Extracellular miR-320a-3p in Patients with Paroxysmal Atrial Fibrillation

The potential of extracellular circulating microRNAs (miRNAs) as non-invasive biomarkers of atrial fibrillation (AF) has been confirmed by a number of recent studies. However, the current data for some miRNAs are controversial and inconsistent, probably due to pre-analytical and methodological differences. In this work, we attempted to fulfill the basic pre-analytical requirements provided for circulating miRNA studies for application to paroxysmal atrial fibrillation (PAF) research. We used quantitative PCR (qPCR) to determine the relative plasma levels of circulating miRNAs expressed in the heart or associated with atrial remodeling or fibrillation with reported altered plasma/serum levels in AF: miR-146a-5p, miR-150-5p, miR-19a-3p, miR-21-5p, miR-29b-3p, miR-320a-3p, miR-328-3p, miR-375-3p, and miR-409-3p. First, in a cohort of 90 adult outpatient clinic patients, we found that the plasma level of miR-320a-3p was elevated in PAF patients compared to healthy controls and hypertensive patients without AF. We further analyzed the impact of medication therapies on miRNA relative levels and found elevated miR-320a-3p levels in patients receiving angiotensin-converting-enzyme inhibitors (ACEI) therapy. Additionally, we found that miR-320a-3p, miR-21-5p, and miR-146a-5p plasma levels positively correlated with the CHA₂DS₂-Vasc score and were elevated in subjects with CHA₂DS₂-Vasc ≥ 2. Our results indicate that, amongst the analyzed miRNAs, miR-320a-3p may be considered as a potential PAF circulating plasma biomarker, leading to speculation as to whether this miRNA is a marker of platelet state change due to ACEI therapy.

Combining Bioinformatics Techniques to Study Diabetes Biomarkers and Related Molecular Mechanisms

Objective

To explore the mechanism of plasma circulating miRNA-126 and miRNA-28-3p in diabetes mellitus (DM) patients, and to identify the related bioinformatics analysis.

Methods

Randomly selected 120 DM patients as the observation group and 120 non- DM patients as the control group. The plasma circulating miRNA-126 and miRNA-28-3p were analyzed by qRT-PCR, and their target genes, biological information, related lncRNA and circRNA were predicted.

Results

The circulating miRNA-126 (0.1162 ± 0.0236 vs. 0.0018 ± 0.0862) and miRNA-28-3p (0.1378 ± 0.0268 vs. 0.0006 ± 0.0167) levels in the observation group were significantly higher than those in the control group, and differences were statistically significant (P < 0.01). The Pearson correlation coefficient of miRNA-126 and miRNA- 28-3p was 0.4337 (P < 0.01). ROC curve analysis of miRNA-126 and miRNA-28-3p showed that the differences of the area under curve were statistically significant between the two groups (P < 0.01). Bioinformatics prediction showed that miRNA-126 and miRNA-28-3p may be involved in regulation of the insulin signaling pathway, insulin receptor signaling pathway, insulin/insulin growth factor signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway and angiogenesis. Moreover, it may be associated with a variety of lncRNA and cir-cRNA.

Conclusion

Circulating miRNA-126 and miRNA-28-3p can be a potential biomarker of DM and it may play an important role in the DM by regulating insulin or insulin growth factor related signaling pathways.