MicroRNA expression in human omental and subcutaneous adipose tissue. PLoS One. 2009;4:e4699. [PMID: 19259271 PMCID: PMC2649537 DOI: 10.1371/journal.pone.0004699]

Deciphering adipose development: Function, differentiation and regulation

The overdevelopment of adipose tissues, accompanied by excess lipid accumulation and energy storage, leads to adipose deposition and obesity. With the increasing incidence of obesity in recent years, obesity is becoming a major risk factor for human health, causing various relevant diseases (including hypertension, diabetes, osteoarthritis and cancers). Therefore, it is of significance to antagonize obesity to reduce the risk of obesity-related diseases. Excess lipid accumulation in adipose tissues is mediated by adipocyte hypertrophy (expansion of pre-existing adipocytes) or hyperplasia (increase of newly-formed adipocytes). It is necessary to prevent excessive accumulation of adipose tissues by controlling adipose development. Adipogenesis is exquisitely regulated by many factors in vivo and in vitro, including hormones, cytokines, gender and dietary components. The present review has concluded a comprehensive understanding of adipose development including its origin, classification, distribution, function, differentiation and molecular mechanisms underlying adipogenesis, which may provide potential therapeutic strategies for harnessing obesity without impairing adipose tissue function.

Bioinformatics Analysis of miR-181a and Its Role in Adipogenesis, Obesity, and Lipid Metabolism Through Review of Literature

The miRNAs regulate various biological processes in the mammalian body system. The role of miR-181a in the development, progression, and expansion of cancers is well-documented. However, the role of miR-181a in adipogenesis; lipid metabolism; obesity; and obesity-related issues such as diabetes mellitus needs to be explored. Therefore, in the present study, the literature was searched and bioinformatics tools were applied to explore the role of miR-181a in adipogenesis. The list of adipogenic and lipogenic target genes validated through different publications were extracted and compiled. The network and functional analysis of these target genes was performed through in-silico analysis. The mature sequence of miR-181a of different species were extracted from and were found highly conserved among the curated species. Additionally, we also used various bioinformatics tools such as target gene extraction from Targetscan, miRWalk, and miRDB, and the list of the target genes from these different databases was compared, and common target genes were predicted. These common target genes were further subjected to the enrichment score and KEGG pathways analysis. The enrichment score of the vital KEGG pathways of the target genes is the key regulator of adipogenesis, lipogenesis, obesity, and obesity-related syndromes in adipose tissues. Therefore, the information presented in the current review will explore the regulatory roles of miR-181a in fat tissues and its associated functions and manifestations.

Longitudinal associations between microRNAs and weight in the diabetes prevention program

Objective

Circulating microRNAs show cross-sectional associations with overweight and obesity. Few studies provided data to differentiate between a snapshot perspective on these associations versus how microRNAs characterize prodromal risk from disease pathology and complications. This study assessed longitudinal relationships between circulating microRNAs and weight at multiple time-points in the Diabetes Prevention Program trial.

Research design and methods

A subset of participants (n=150) from the Diabetes Prevention Program were included. MicroRNAs were measured from banked plasma using a Fireplex Assay. We used generalized linear mixed models to evaluate relationships between microRNAs and changes in weight at baseline, year-1, and year-2. Logistic regression was used to evaluate whether microRNAs at baseline were associated with weight change after 2 years.

Results

In fully adjusted models that included relevant covariates, seven miRs (i.e., miR-126, miR-15a, miR-192, miR-23a, and miR-27a) were statistically associated with weight over 2 years. MiR-197 and miR-320a remained significant after adjustment for multiple comparisons. Baseline levels of let-7f, miR-17, and miR-320c were significantly associated with 3% weight loss after 2 years in fully adjusted models.

Discussion

This study provided evidence for longitudinal relationships between circulating microRNAs and weight. Because microRNAs characterize the combined effects of genetic determinants and responses to behavioral determinants, they may provide insights about the etiology of overweight and obesity in the context or risk for common, complex diseases. Additional studies are needed to validate the potential genes and biological pathways that might be targeted by these microRNA biomarkers and have mechanistic implications for weight loss and disease prevention.

miRNA and leptin signaling in metabolic diseases and at extreme environments

The burden of growing concern about the dysregulation of metabolic processes arises due to complex interplay between environment and nutrition that has great impact on genetics and epigenetics of an individual. Thereby, any abnormality at the level of food intake regulating hormones may contribute to the development of metabolic diseases in any age group due to malnutrition, overweight, changing lifestyle, and exposure to extreme environments such as heat stress (HS), cold stress, or high altitude (HA). Hormones such as leptin, adiponectin, ghrelin, and cholecystokinin regulate appetite and satiety to maintain energy homeostasis. Leptin, an adipokine and a pleiotropic hormone, play major role in regulating the food intake, energy gain and energy expenditure. Using in silico approach, we have identified the major genes (LEP, LEPR, JAK2, STAT3, NPY, POMC, IRS1, SOCS3) that play crucial role in leptin signaling pathway. Further, eight miRNAs (hsa-miR-204-5p, hsa-miR-211-5p, hsa-miR-30, hsa-miR-3163, hsa-miR-33a-3p, hsa-miR-548, hsa-miR-561-3p, hsa-miR-7856-5p) from TargetScan 8.0 database were screened out that commonly target these genes. The role of these miRNAs should be explored as they might play vital role in regulating the appetite, energy metabolism, metabolic diseases (obesity, type 2 diabetes, cardiovascular diseases, inflammation), and to combat extreme environments. The miRNAs regulating leptin signaling and appetite may be useful for developing novel therapeutics for metabolic diseases.

Regulatory Roles of MicroRNAs in the Pathogenesis of Metabolic Syndrome

Metabolic syndrome refers to a group of several disease conditions together with high glucose triglyceride levels, high blood pressure, lower high-density lipoprotein level, and large waist circumference. About 400 million people worldwide, one-third of the Euro-American population and 27% Chinese population over age 50 have it. microRNAs, an abundant novel class of endogenous small, non-coding RNAs in eukaryotic cells, act as negative controllers of gene expression by promoting either degradation/translational repression of target messenger RNA. More than 2000 microRNAs in the human genome have been identified and they are implicated in various biological & pathophysiological processes, including glucose homeostasis, inflammatory response, and angiogenesis. Destruction of microRNAs has a crucial role in the pathogenesis of obesity, cardiovascular disease, and diabetes. Recently the discovery of circulating microRNAs in human serum may help to promote metabolic crosstalk between organs and serves as a novel approach for the identification of various diseases, like Type 2 diabetes & atherosclerosis. In this review, we will discuss the most recent and up-to-date research on the pathophysiology and histopathology of metabolic syndrome besides their historical background and epidemiological highlight. As well as search the methodologies employed in this field of research and the potential role of microRNAs as novel biomarkers and therapeutic targets for metabolic syndrome in the human body. Furthermore, the significance of microRNAs in promising strategies, like stem cell therapy, which holds enormous promise for regenerative medicine in the treatment of metabolic disorders will also be discussed.

Research Progress on Micro (Nano)Plastics Exposure-Induced miRNA-Mediated Biotoxicity

Micro- and nano-plastics (MNPs) are ubiquitously distributed in the environment, infiltrate organisms through multiple pathways, and accumulate, thus posing potential threats to human health. MNP exposure elicits changes in microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), thereby precipitating immune, neurological, and other toxic effects. The investigation of MNP exposure and its effect on miRNA expression has garnered increasing attention. Following MNP exposure, circRNAs serve as miRNA sponges by modulating gene expression, while lncRNAs function as competing endogenous RNAs (ceRNAs) by fine-tuning target gene expression and consequently impacting protein translation and physiological processes in cells. Dysregulated miRNA expression mediates mitochondrial dysfunction, inflammation, and oxidative stress, thereby increasing the risk of neurodegenerative diseases, cardiovascular diseases, and cancer. This tract, blood, urine, feces, placenta, and review delves into the biotoxicity arising from dysregulated miRNA expression due to MNP exposure and addresses the challenges encountered in this field. This study provides novel insights into the connections between MNPs and disease risk.

Selected microRNA Expression and Protein Regulator Secretion by Adipose Tissue-Derived Mesenchymal Stem Cells and Metabolic Syndrome

The role of adipose mesenchymal stem cells (Ad-MSCs) in metabolic syndrome remains unclear. We aimed to assess the expression of selected microRNAs in Ad-MSCs of non-diabetic adults in relation to Ad-MSC secretion of protein regulators and basic metabolic parameters. Ten obese, eight overweight, and five normal weight subjects were enrolled: 19 females and 4 males; aged 43.0 ± 8.9 years. Ad-MSCs were harvested from abdominal subcutaneous fat. Ad-MSC cellular expressions of four microRNAs (2-ΔCt values) and concentrations of IL-6, IL-10, VEGF, and IGF-1 in the Ad-MSC-conditioned medium were assessed. The expressions of miR-21, miR-122, or miR-192 did not correlate with clinical parameters (age, sex, BMI, visceral fat, HOMA-IR, fasting glycemia, HbA1c, serum lipids, CRP, and eGFR). Conversely, the expression of miR-155 was lowest in obese subjects (3.69 ± 2.67 × 10-3 vs. 7.07 ± 4.42 × 10-3 in overweight and 10.25 ± 7.05 × 10-3 in normal weight ones, p = 0.04). The expression of miR-155 correlated inversely with BMI (sex-adjusted r = -0.64; p < 0.01), visceral adiposity (r = -0.49; p = 0.03), and serum CRP (r = -0.63; p < 0.01), whereas it correlated positively with serum HDL cholesterol (r = 0.51; p = 0.02). Moreover, miR-155 synthesis was associated marginally negatively with Ad-MSC secretion of IGF-1 (r = -0.42; p = 0.05), and positively with that of IL-10 (r = 0.40; p = 0.06). Ad-MSC expression of miR-155 appears blunted in visceral obesity, which correlates with Ad-MSC IGF-1 hypersecretion and IL-10 hyposecretion, systemic microinflammation, and HDL dyslipidemia. Ad-MSC studies in metabolic syndrome should focus on miR-155.

Longitudinal Associations Between MicroRNAs and Weight in the Diabetes Prevention Program

OBJECTIVE

Circulating microRNAs show cross-sectional associations with overweight and obesity. Few studies provided data to differentiate between a snapshot perspective on these associations versus how microRNAs characterize prodromal risk from disease pathology and complications. This study assessed longitudinal relationships between circulating microRNAs and weight at multiple time-points in the Diabetes Prevention Program trial.

RESEARCH DESIGN AND METHODS

A subset of participants (n=150) from the Diabetes Prevention Program were included. MicroRNAs were measured from banked plasma using a Fireplex Assay. We used generalized linear mixed models to evaluate relationships between microRNAs and changes in weight at baseline, year-1, and year-2. Logistic regression was used to evaluate whether microRNAs at baseline were associated with weight change after 2 years.

RESULTS

In fully adjusted models that included relevant covariates, seven miRs (i.e., miR-126, miR-15a, miR-192, miR-23a, and miR-27a) were statistically associated with weight over 2 years. MiR-197 and miR-320a remained significant after adjustment for multiple comparisons. Baseline levels of let-7f, miR-17, and miR-320c were significantly associated with 3% weight loss after 2 years in fully adjusted models.

DISCUSSION

This study provided evidence for longitudinal relationships between circulating microRNAs and weight. Because microRNAs characterize the combined effects of genetic determinants and responses to behavioral determinants, they may provide insights about the etiology of overweight and obesity in the context or risk for common, complex diseases. Additional studies are needed to validate the potential genes and biological pathways that might be targeted by these microRNA biomarkers and have mechanistic implications for weight loss and disease prevention.

Effects of HIIT training and HIIT combined with circuit resistance training on measures of physical fitness, miRNA expression, and metabolic risk factors in overweight/obese middle-aged women

OBJECTIVE

The purpose of this study was to examine the effects of 10 weeks of high-intensity interval training (HIIT) and HIIT combined with circuit resistance training (HCRT) on selected measures of physical fitness, the expression of miR-9, -15a, -34a, -145, and - 155 as well as metabolic risk factors including lipid profiles and insulin resistance in middle-aged overweight/obese women.

METHODS

Twenty-seven overweight/obese women aged 35-50 yrs. were randomized to HIIT (n = 14) or HCRT (n = 13) groups. The HIIT group performed running exercises (5 reps x 4 min per session) with active recovery between repetitions for 10 weeks with 5 weekly sessions. The HCRT group performed 10 weeks of HIIT and resistance training with 3 weekly HIIT sessions and 2 weekly HCRT sessions. Anthropometric measures (e.g., body mass), selected components of physical fitness (cardiovascular fitness, muscle strength), levels of miRNAs (miR-9, -15a, -34a, -145, and - 155), lipid profiles (total cholesterol; TC, Triglycerides; TG, low-density lipoprotein cholesterol; LDL-C and high-density lipoprotein cholesterol; HDL-C), and insulin resistance; HOMA-IR index, were measured at baseline and week 10.

RESULTS

An ANOVA analysis indicated no significant group by time interactions (p > 0.05) for all anthropometric measures, and maximum oxygen consumption (VO2max). A significant group by time interaction, however, was found for the one-repetition maximum (IRM; p < 0.001, ES= 0.751 , moderate). A post-hoc test indicated an increase in the pre-to-post mean 1RM for HCRT (p = 0.001, ES = 1.83, large). There was a significant group by time interaction for miR-155 (p = 0.05, ES = 0.014, trivial). Levels for miR-155 underwent pre-to-post HIIT increases (p = 0.045, ES = 1.232, large). Moreover, there were also significant group by time interactions for TC (p = 0.035, ES = 0.187, trivial), TG (p < 0.001, ES = 0.586, small), LDL-C (p = 0.029, ES = 0.200, small) and HDL-C (p = 0.009, ES = 0.273, small). Post-hoc tests indicated pre-post HCRT decreases for TC (p = 0.001, ES = 1.44, large) and HDL-C (p = 0.001, ES = 1.407, large). HIIT caused pre-to-post decreases in TG (p = 0.001, ES = 0.599, small), and LDL-C (p = 0.001, ES = 0.926, moderate).

CONCLUSIONS

Both training regimes did not improve cardiovascular fitness. But, HCRT improved lower/upper limb muscle strength, and HIIT resulted in an increase in miR-155 expression in peripheral blood mononuclear cells. Furthermore, HIIT and HCRT each improved selected metabolic risk factors including lipid profiles and glucose and insulin metabolism in overweight/obese middle-aged women.

TRIAL REGISTRATION

OSF, October, 4th 2023. Registration DOI: https://doi.org/10.17605/OSF.IO/UZ92E . osf.io/tc5ky . "Retrospectively registered".

MicroRNAs Associated with Metformin Treatment in the Diabetes Prevention Program

The Diabetes Prevention Program (DPP) randomized controlled trial demonstrated that metformin treatment reduced progression to type 2 diabetes (T2D) by 31% compared to placebo in adults with prediabetes. Circulating micro-ribonucleic acids (miRs) are promising biomarkers of T2D risk, but little is known about their associations with metformin regimens for T2D risk reduction. We compared the change in 24 circulating miRs from baseline to 2 years in a subset from DPP metformin intervention (n = 50) and placebo (n = 50) groups using Wilcoxon signed rank tests. Spearman correlations were used to evaluate associations between miR change and baseline clinical characteristics. Multiple linear regression was used to adjust for covariates. The sample was 73% female, 17% Black, 13% Hispanic, and 50 ± 11 years. Participants were obese, normotensive, prediabetic, and dyslipidemic. Change in 12 miR levels from baseline to 2 years was significantly different in the metformin group compared with placebo after adjusting for multiple comparisons: six (let-7c-5p, miR-151a-3p, miR-17-5p, miR-20b-5p, miR-29b-3p, and miR-93-5p) were significantly upregulated and six (miR-130b-3p, miR-22-3p, miR-222-3p, miR-320a-3p, miR-320c, miR-92a-3p) were significantly downregulated in the metformin group. These miRs help to explain how metformin is linked to T2D risk reduction, which may lead to novel biomarkers, therapeutics, and precision health strategies.

Ketogenic Diet Induced Shifts in the Gut Microbiome Associate with Changes to Inflammatory Cytokines and Brain-Related miRNAs in Children with Autism Spectrum Disorder

In this interventional pilot study, we investigated the effects of a modified ketogenic diet (KD) on children with autism spectrum disorder (ASD). We previously observed improved behavioral symptoms in this cohort following the KD; this trial was registered with Clinicaltrials.gov (NCT02477904). This report details the alterations observed in the microbiota, inflammation markers, and microRNAs of seven children following a KD for a duration of 4 months. Our analysis included blood and stool samples, collected before and after the KD. After 4 months follow up, we found that the KD led to decreased plasma levels of proinflammatory cytokines (IL-12p70 and IL-1b) and brain-derived neurotrophic factor (BDNF). Additionally, we observed changes in the gut microbiome, increased expression of butyrate kinase in the gut, and altered levels of BDNF-associated miRNAs in the plasma. These cohort findings suggest that the KD may positively influence ASD sociability, as previously observed, by reducing inflammation, reversing gut microbial dysbiosis, and impacting the BDNF pathway related to brain activity.

Differentiation of Adipose Tissue Mesenchymal Stem Cells into Endothelial Cells Depends on Fat Depot Conditions: Regulation by miRNA

The development of obesity is associated with substantial modulation of adipose tissue (AT) structure. The plasticity of the AT is reflected by its remarkable ability to expand or reduce in size throughout the adult lifespan, which is linked to the development of its vasculature. This increase in AT vasculature could be mediated by the differentiation of adipose tissue-derived stem cells (ASCs) into endothelial cells (ECs) and form new microvasculature. We have already shown that microRNA (miRNA)-145 regulates the differentiation of ASCs into EC-like (ECL) cells. Here, we investigated whether ASCs-differentiation into ECs is governed by a miRNAs signature that depends on fat depot location and /or the metabolic condition produced by obesity. Human ASCs, which were obtained from white AT by surgical procedures from lean and obese patients, were induced to differentiate into ECL cells. We have identified that miRNA-29b-3p in both subcutaneous (s)ASCs and visceral ASCs and miRNA-424-5p and miRNA-378a-3p in subcutaneous (s)ASCs are involved in differentiation into EC-like cells. These miRNAs modulate their pro-angiogenic effects on ASCs by targeting FGFR1, NRP2, MAPK1, and TGF-β2, and the MAPK signaling pathway. We show for the first time that miRNA-29b-3p upregulation contributes to ASCs' differentiation into ECL cells by directly targeting TGFB2 in both sASCs and visceral ASCs. Moreover, our results reveal that, independent of sASCs' origin (obese/lean), the upregulation of miRNA-378a-3p and the downregulation of miRNA-424-5p inhibit MAPK1 and overexpress FGFR1 and NRP2, respectively. In summary, both the adipose depot location and obesity affect the differentiation of resident ASCs through the expression of specific miRNAs.

MicroRNAs Associated with Metformin Treatment in the Diabetes Prevention Program

The Diabetes Prevention Program (DPP) randomized controlled trial demonstrated that metformin treatment reduced progression to type 2 diabetes (T2D) by 31% compared to placebo in adults with prediabetes. Circulating micro-ribonucleic acids (miRs) are promising biomarkers of T2D risk, but little is known about their associations with metformin regimens for T2D risk reduction. We compared the change in 24 circulating miRs from baseline to 2 years in a subset from DPP metformin intervention (n = 50) and placebo (n = 50) groups using Wilcoxon signed rank tests. Spearman's correlations were used to evaluate associations between miR change and baseline clinical characteristics. Multiple linear regression was used to adjust for covariates. The sample was 73% female, 17% Black, 13% Hispanic, and 50 ± 11 years. Participants were obese, normotensive, prediabetic, and dyslipidemic. Change in 12 miR levels from baseline to 2 years was significantly different in the metformin group compared with placebo after adjusting for multiple comparisons: six (let-7c-5p, miR-151a-3p, miR-17-5p, miR-20b-5p, miR-29b-3p, and miR-93-5p) were significantly upregulated and six (miR-130b-3p, miR-22-3p, miR-222-3p, miR-320a-3p, miR-320c, miR-92a-3p) were significantly downregulated in the metformin group. These miRs help to explain how metformin is linked to T2D risk reduction, which may lead to novel biomarkers, therapeutics, and precision-health strategies.

MicroRNAs as Epigenetic Regulators of Obesity

In obesity, the process of adipogenesis largely determines the number of adipocytes in body fat depots. Adipogenesis is regulated by several adipocyte-selective micro-ribonucleic acids (miRNAs) and transcription factors that modulate adipocyte proliferation and differentiation. However, some miRNAs block the expression of master regulators of adipogenesis. Since the specific miRNAs display different expressions during adipogenesis, in mature adipocytes and permanent obesity, their use as biomarkers or therapeutic targets is feasible. Upregulated miRNAs in persistent obesity are downregulated during adipogenesis. Moreover, some of the downregulated miRNAs in obese individuals are upregulated in mature adipocytes. Induction of adipocyte stress and hypertrophy leads to the release of adipocyte-derived exosomes (AdEXs) that contain the cargo molecules, miRNAs. miRNAs are important messengers for intercellular communication involved in metabolic responses and have very specific signatures that direct the metabolic activity of target cells. While each miRNA targets multiple messenger RNAs (mRNAs), which may coordinate or antagonize each other's functions, several miRNAs are dysregulated in other tissues during obesity-related comorbidities. Deletion of the miRNA-processing enzyme DICER in pro-opiomelanocortin-expressing cells results in obesity, which is characterized by hyperphagia, increased adiposity, hyperleptinemia, defective glucose metabolism, and alterations in the pituitary-adrenal axis. In recent years, RNA-based therapeutical approaches have entered clinical trials as novel therapies against overweight and its complications. Development of lipid droplets, macrophage accumulation, macrophage polarization, tumor necrosis factor receptor-associated factor 6 activity, lipolysis, lipotoxicity, and insulin resistance are effectively controlled by miRNAs. Thereby, miRNAs as epigenetic regulators are used to determine the new gene transcripts and therapeutic targets.

Modulation of Neuronal Damage in DRG by Asprosin in a High-Glucose Environment and Its Impact on miRNA181-a Expression in Diabetic DRG

Asprosin, a hormone secreted from adipose tissue, has been implicated in the modulation of cell viability. Current studies suggest that neurological impairments are increased in individuals with obesity-linked diabetes, likely due to the presence of excess adipose tissue, but the precise molecular mechanism behind this association remains poorly understood. In this study, our hypothesis that asprosin has the potential to mitigate neuronal damage in a high glucose (HG) environment while also regulating the expression of microRNA (miRNA)-181a, which is involved in critical biological processes such as cellular survival, apoptosis, and autophagy. To investigate this, dorsal root ganglion (DRG) neurons were exposed to asprosin in a HG (45 mmol/L) environment for 24 hours, with a focus on the role of the protein kinase A (PKA) pathway. Expression of miRNA-181a was measured by using real-time polymerase chain reaction (RT-PCR) in diabetic DRG. Our findings revealed a decline in cell viability and an upregulation of apoptosis under HG conditions. However, pretreatment with asprosin in sensory neurons effectively improved cell viability and reduced apoptosis by activating the PKA pathway. Furthermore, we observed that asprosin modulated the expression of miRNA-181a in diabetic DRG. Our study demonstrates that asprosin has the potential to protect DRG neurons from HG-induced damage while influencing miRNA-181a expression in diabetic DRG. These findings provide valuable insights for the development of clinical interventions targeting neurotoxicity in diabetes, with asprosin emerging as a promising therapeutic target for managing neurological complications in affected individuals.

Plasma microRNA Profiling in Type 2 Diabetes Mellitus: A Pilot Study

Type 2 diabetes mellitus (T2D) is a chronic metabolic disease characterized by insulin resistance and β-cell dysfunction and leading to many micro- and macrovascular complications. In this study we analyzed the circulating miRNA expression profiles in plasma samples from 44 patients with T2D and 22 healthy individuals using next generation sequencing and detected 229 differentially expressed miRNAs. An increased level of miR-5588-5p, miR-125b-2-3p, miR-1284, and a reduced level of miR-496 in T2D patients was verified. We also compared the expression landscapes in the same group of patients depending on body mass index and identified differential expression of miR-144-3p and miR-99a-5p in obese individuals. Identification and functional analysis of putative target genes was performed for miR-5588-5p, miR-125b-2-3p, miR-1284, and miR-496, showing chromatin modifying enzymes and apoptotic genes being among the significantly enriched pathways.

Molecular mechanisms of noncoding RNA and epigenetic regulation in obesity with consequent diabetes mellitus development

Diabetes mellitus (DM) and obesity have become two of the most prevalent and challenging diseases worldwide, with increasing incidence and serious complications. Recent studies have shown that noncoding RNA (ncRNA) and epigenetic regulation play crucial roles in the pathogenesis of DM complicated by obesity. Identification of the involvement of ncRNA and epigenetic regulation in the pathogenesis of diabetes with obesity has opened new avenues of investigation. Targeting these mechanisms with small molecules or RNA-based therapies may provide a more precise and effective approach to diabetes treatment than traditional therapies. In this review, we discuss the molecular mechanisms of ncRNA and epigenetic regulation and their potential therapeutic targets, and the research prospects for DM complicated with obesity.

Identification of novel circulating miRNAs biomarkers for healthy obese and lean children

BACKGROUND

The prevalence of childhood obesity and overweight has risen globally, leading to increased rates of metabolic disorders. Various factors, including genetic, epigenetic, and environmental influences such as diet and physical activity, contribute to pediatric obesity. This study aimed to identify specific circulating miRNAs as potential biomarkers for assessing obesity in children.

METHODS

Thirty children, including 15 obese and 15 extremely thin individuals, were selected for this study. MiRNA expression in circulating plasma was assessed using miRNA microarrays. The reliability of differential miRNA expression was confirmed using TaqMan qPCR. The correlation between miRNAs and obesity was analyzed through multiple linear regression, receiver operator characteristic (ROC) curve analysis, and odds ratio (OR) calculations. Bioinformatics tools were utilized to identify target genes for the selected miRNAs, and a functional network map was constructed.

RESULTS

A total of 36 differentially expressed miRNAs were identified through gene chip analysis, and TaqMan qPCR validation confirmed the upregulation of seven miRNAs: hsa-miR-126-3p, hsa-miR-15b-5p, hsa-miR-199a-3p, hsa-miR-20a-5p, hsa-miR-223-3p, hsa-miR-23a-3p, and hsa-miR-24-3p. Among these, hsa-miR-15b-5p and hsa-miR-223-3p exhibited a statistically significant difference except for hsa-miR-23a-3p. These two miRNAs showed more predicted target genes related to obesity than others. Multiple linear regression analysis revealed an association between obesity and hsa-miR-15b-5p and hsa-miR-223-3p [10.529 (4.974-16.084), -10.225 (-17.852~ -2.657)]. Even after adjusting for age and sex, these two miRNAs remained associated with obesity [8.936 (3.572-14.301), -8.449(-15.634~ -1.303)]. The area under the ROC curve (AUC) reached values of 0.816, 0.711, and 0.929, respectively. Odds ratio analysis demonstrated a significant correlation between obesity and hsa-miR-15b-5p (OR = 143, 95% CI 5.80 to 56,313, p = 0.024) and between obesity and hsa-miR-223-3p (OR = 0.01, 95% CI 0.00 to 0.23, p = 0.037). Importantly, hsa-miR-15b-5p was found to have numerous target genes associated with the FoxO, insulin, Ras, and AMPK signaling pathways.

CONCLUSIONS

Differential miRNA expression profiles in the circulation of obese children compared to controls suggest underlying metabolic abnormalities. Hsa-miR-15b-5p and hsa-miR-223-3p may be considered as molecular markers for the screening of obese children and populations at risk of developing metabolic syndrome.

Novel insights regarding the role of noncoding RNAs in diabetes

Diabetes mellitus (DM) is a group of metabolic disorders defined by hyperglycemia induced by insulin resistance, inadequate insulin secretion, or excessive glucagon secretion. In 2021, the global prevalence of diabetes is anticipated to be 10.7% (537 million people). Noncoding RNAs (ncRNAs) appear to have an important role in the initiation and progression of DM, according to a growing body of research. The two major groups of ncRNAs implicated in diabetic disorders are miRNAs and long noncoding RNAs. miRNAs are single-stranded, short (17–25 nucleotides), ncRNAs that influence gene expression at the post-transcriptional level. Because DM has reached epidemic proportions worldwide, it appears that novel diagnostic and therapeutic strategies are required to identify and treat complications associated with these diseases efficiently. miRNAs are gaining attention as biomarkers for DM diagnosis and potential treatment due to their function in maintaining physiological homeostasis via gene expression regulation. In this review, we address the issue of the gradually expanding global prevalence of DM by presenting a complete and up-to-date synopsis of various regulatory miRNAs involved in these disorders. We hope this review will spark discussion about ncRNAs as prognostic biomarkers and therapeutic tools for DM. We examine and synthesize recent research that used novel, high-throughput technologies to uncover ncRNAs involved in DM, necessitating a systematic approach to examining and summarizing their roles and possible diagnostic and therapeutic uses.

Expression Analysis of hsa-miR-181a-5p, hsa-miR-143-3p, hsa-miR-132-3p and hsa-miR-23a-3p as Biomarkers in Colorectal Cancer-Relationship to the Body Mass Index

This work aims to investigate the expression levels of four preselected miRNAs previously linked to cancer and/or obesity, with the purpose of finding potential biomarkers in the clinical management of CRC developed by patients showing different BMI values. We analyzed samples from a total of 65 subjects: 43 affected by CRC and 22 without cancer. Serum and both subcutaneous and omental adipose tissues (SAT and OAT) were investigated, as well as tumor and non-tumor colorectal tissues in the case of the CRC patients. The relative expression (2^-∆∆Ct) levels of 4 miRNAs (hsa-miR-181a-5p, hsa-miR-143-3p, has-miR-132-3p and hsa-miR-23a-3p) were measured by RT-qPCR. Serum, SAT and OAT expression levels of these miRNAs showed significant differences between subjects with and without CRC, especially in the group of overweight/obese subjects. In CRC, serum levels of hsa-miR-143-3p clearly correlated with their levels in both SAT and OAT, independently of the BMI group. Moreover, hsa-miR-181a-5p could be considered as a biomarker in CRC patients with BMI ≥ 25 Kg/m² and emerges as a tumor location marker. We conclude that both adiposity and CRC induce changes in the expression of the miRNAs investigated, and hsa-miR-143-3p and hsa-miR-181a-5p expression analysis could be useful in the clinical management of CRC.

Metabolo-epigenetic interplay provides targeted nutritional interventions in chronic diseases and ageing

Epigenetic modifications are chemical modifications that affect gene expression without altering DNA sequences. In particular, epigenetic chemical modifications can occur on histone proteins -mainly acetylation, methylation-, and on DNA and RNA molecules -mainly methylation-. Additional mechanisms, such as RNA-mediated regulation of gene expression and determinants of the genomic architecture can also affect gene expression. Importantly, depending on the cellular context and environment, epigenetic processes can drive developmental programs as well as functional plasticity. However, misbalanced epigenetic regulation can result in disease, particularly in the context of metabolic diseases, cancer, and ageing. Non-communicable chronic diseases (NCCD) and ageing share common features including altered metabolism, systemic meta-inflammation, dysfunctional immune system responses, and oxidative stress, among others. In this scenario, unbalanced diets, such as high sugar and high saturated fatty acids consumption, together with sedentary habits, are risk factors implicated in the development of NCCD and premature ageing. The nutritional and metabolic status of individuals interact with epigenetics at different levels. Thus, it is crucial to understand how we can modulate epigenetic marks through both lifestyle habits and targeted clinical interventions -including fasting mimicking diets, nutraceuticals, and bioactive compounds- which will contribute to restore the metabolic homeostasis in NCCD. Here, we first describe key metabolites from cellular metabolic pathways used as substrates to "write" the epigenetic marks; and cofactors that modulate the activity of the epigenetic enzymes; then, we briefly show how metabolic and epigenetic imbalances may result in disease; and, finally, we show several examples of nutritional interventions - diet based interventions, bioactive compounds, and nutraceuticals- and exercise to counteract epigenetic alterations.

A Liquid Biopsy-Based Approach to Isolate and Characterize Adipose Tissue-Derived Extracellular Vesicles from Blood

Obesity is a major risk factor for multiple chronic diseases. Anthropometric and imaging approaches are primarily used to assess adiposity, and there is a dearth of techniques to determine the changes in adipose tissue (AT) at the molecular level. Extracellular vesicles (EVs) have emerged as a novel and less invasive source of biomarkers for various pathologies. Furthermore, the possibility of enriching cell or tissue-specific EVs from the biofluids based on their unique surface markers has led to classifying these vesicles as "liquid biopsies", offering valuable molecular information on hard-to-access tissues. Here, we isolated small EVs from AT (sEVAT) of lean and diet-induced obese (DIO) mice, identified unique surface proteins on sEVAT by surface shaving followed by mass spectrometry, and developed a signature of five unique proteins. Using this signature, we pulled out sEVAT from the blood of mice and validated the specificity of isolated sEVAT by measuring the expression of adiponectin, 38 adipokines on an array, and several adipose tissue-related miRNAs. Furthermore, we provided evidence of sEV applicability in disease prediction by characterizing sEVAT from the blood of lean and DIO mice. Interestingly, sEVAT-DIO cargo showed a stronger pro-inflammatory effect on THP1 monocytes compared to sEVAT-Lean and a significant increase in obesity-associated miRNA expression. Equally important, sEVAT cargo revealed an obesity-associated aberrant amino acid metabolism that was subsequently validated in the corresponding AT. Lastly, we show a significant increase in inflammation-related molecules in sEVAT isolated from the blood of nondiabetic obese (>30 kg/m2) individuals. Overall, the present study offers a less-invasive approach to characterize AT.

Effect of miR-149-5p on intramuscular fat deposition in pigs based on metabolomics and transcriptomics

As one of the important traits in pig production, meat quality has important research significance and value. Intramuscular fat (IMF) content is one of the most important factors affecting pork quality. Many experimental studies have shown that IMF content is closely related to the flavor, tenderness, and juiciness of pork. Therefore, it is of great significance to study the mechanism of porcine IMF deposition. Previous research indicated that miR-149-5p promoted the proliferation of porcine intramuscular (IM) preadipocytes and decreased their ability to differentiate, albeit the exact mechanism of action is unknown. In vitro, foreign pigs showed increased miR-149-5p expression and reduced fat deposition when compared to Queshan Black pigs. This study conducted metabolomics and transcriptomics analyses of porcine IM preadipocytes overexpressing miR-149-5p to verify their effects on lipid formation. According to metabolomics analysis, the overexpression of miR-149-5p has significantly altered the lipid, organic acid, and organic oxygen metabolites of porcine IM preadipocytes. Specially speaking, it has changed 115 metabolites, including 105 up-regulated and 10 down-regulated ones, as well as the composition of lipid, organic acid, and organic oxygen metabolism-related metabolites. RNA-seq analysis showed that overexpression of miR-149-5p significantly altered 857 genes, of which 442 were up-regulated, and 415 were down-regulated, with enrichment to MAPK, IL-17, PI3K-Akt, and ErbB signaling pathways. We found that overexpression of miR-149-5p inhibited adipogenic differentiation by changing cAMP signaling pathway in porcine IM preadipocytes. In addition, the overexpression of miR-149-5p may affect the transport of Cu²⁺ by targeting ATP7A and inhibiting adipogenic differentiation. These findings elucidate the regulatory function of miR-149-5p in porcine IM preadipocytes, which may be a key target for controlling pork quality.

Computational assessment of the biological response of curcumin to type 2 diabetes mellitus induced by metal exposure

The current study aimed to identify the molecular mechanisms of a metal mixture (cadmium, nickel, and lead) involved in type 2 diabetes mellitus (T2DM) development and the therapeutic effect of curcumin in this metal mixture-induced T2DM. To accomplish this, SwissADME assessed the physicochemical and pharmacokinetic properties of curcumin and the Prediction of Activity Spectra for Substances evaluates its biological activities. The Comparative Toxicogenomics Database, Cytoscape, AutoDock Vina, and MicroRNA ENrichment TURned NETwork were used as tools to perform data-mining approaches and molecular docking. Curcumin properties were fitted within the acceptable range to be a promising drug candidate. The mixed metal altered 23 genes linked to T2DM development and targeted by curcumin. Curcumin had a dual-natured effect or antagonistic effect for most of the involved genes in T2DM and metal mixture. The most prominent biological processes were identified as ''response to external stimulus'', ''regulation of programmed cell death'', ''programmed cell death'', ''cell death'', and ''response to stress''. Three highly interacted miRNAs related to metal mixture-induced T2DM and targeted by curcumin (hsa-miR-98-5p, hsa-miR-34a-5p, and hsa-miR-155-5p) were identified. These findings could pave the way for further studies to evaluate the link between these genes and T2DM.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

Circulating miRNAs associated with nonalcoholic fatty liver disease

MicroRNAs (miRNAs) are secreted from cells as either protein-bound or enclosed in extracellular vesicles. Circulating liver-derived miRNAs are modifiable by weight-loss or insulin-sensitizing treatments, indicating that they could be important biomarker candidates for diagnosis, monitoring, and prognosis in nonalcoholic liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Unfortunately, the noninvasive diagnosis of NASH and fibrosis remains a key challenge, which limits case finding. Current diagnostic guidelines, therefore, recommend liver biopsies, with risks of pain and bleeding for the patient and substantial healthcare costs. Here, we summarize mechanisms of RNA secretion and review circulating RNAs associated with NAFLD and NASH for their biomarker potential. Few circulating miRNAs are consistently associated with NAFLD/NASH: miR-122, miR-21, miR-34a, miR-192, miR-193, and the miR-17-92 miRNA-cluster. The hepatocyte-enriched miRNA-122 is consistently increased in NAFLD and NASH but decreased in liver cirrhosis. Circulating miR-34a, part of an existing diagnostic algorithm for NAFLD, and miR-21 are consistently increased in NAFLD and NASH. MiR-192 appears to be prominently upregulated in NASH compared with NAFDL, whereas miR-193 was reported to distinguish NASH from fibrosis. Various members of miRNA cluster miR-17-92 are reported to be associated with NAFLD and NASH, although with less consistency. Several other circulating miRNAs have been reported to be associated with fatty liver in a few studies, indicating the existence of more circulating miRNAs with relevant as diagnostic markers for NAFLD or NASH. Thus, circulating miRNAs show potential as biomarkers of fatty liver disease, but more information about phenotype specificity and longitudinal regulation is needed.

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.

MicroRNAs as Mediators of Adipose Thermogenesis and Potential Therapeutic Targets for Obesity

Obesity is a growing health problem worldwide, associated with an increased risk of multiple chronic diseases. The thermogenic activity of brown adipose tissue (BAT) correlates with leanness in adults. Understanding the mechanisms behind BAT activation and the process of white fat "browning" has important implications for developing new treatments to combat obesity. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in various tissues, including adipose tissue. Recent studies show that miRNAs are involved in adipogenesis and adipose tissue thermogenesis. In this review, we discuss recent advances in the role of miRNAs in adipocyte thermogenesis and obesity. The potential for miRNA-based therapies for obesity and recommendations for future research are highlighted, which may help provide new targets for treating obesity and obesity-related diseases.

Multiomics reveal unique signatures of human epiploic adipose tissue related to systemic insulin resistance

OBJECTIVE

Human white adipose tissue (AT) is a metabolically active organ with distinct depot-specific functions. Despite their locations close to the gastrointestinal tract, mesenteric AT and epiploic AT (epiAT) have only scarcely been investigated. Here, we aim to characterise these ATs in-depth and estimate their contribution to alterations in whole-body metabolism.

DESIGN

Mesenteric, epiploic, omental and abdominal subcutaneous ATs were collected from 70 patients with obesity undergoing Roux-en-Y gastric bypass surgery. The metabolically well-characterised cohort included nine subjects with insulin sensitive (IS) obesity, whose AT samples were analysed in a multiomics approach, including methylome, transcriptome and proteome along with samples from subjects with insulin resistance (IR) matched for age, sex and body mass index (n=9). Findings implying differences between AT depots in these subgroups were validated in the entire cohort (n=70) by quantitative real-time PCR.

RESULTS

While mesenteric AT exhibited signatures similar to those found in the omental depot, epiAT was distinct from all other studied fat depots. Multiomics allowed clear discrimination between the IS and IR states in all tissues. The highest discriminatory power between IS and IR was seen in epiAT, where profound differences in the regulation of developmental, metabolic and inflammatory pathways were observed. Gene expression levels of key molecules involved in AT function, metabolic homeostasis and inflammation revealed significant depot-specific differences with epiAT showing the highest expression levels.

CONCLUSION

Multi-omics epiAT signatures reflect systemic IR and obesity subphenotypes distinct from other fat depots. Our data suggest a previously unrecognised role of human epiploic fat in the context of obesity, impaired insulin sensitivity and related diseases.

Evaluation of circulating extracellular vesicles and miRNA in neutered and obese female dogs

Adipose tissue is a metabolic and endocrine organ, and its adipocytes can synthesize and secrete extracellular vesicles (EVs), thus allowing intercellular communication. EVs are nanoparticles that transport lipids, proteins, metabolites, and nucleic acids (mRNA and microRNAs). MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression. miR-132, miR-26b, and miR-155 are associated with obesity, lipid metabolism and adipogenesis. The aim of this study was to evaluate the enriched EVs fraction containing miRNAs (miR-132, miR-26b, and miR-155) in serum from obese female dogs. Thirty-two neutered females in good general condition were recruited, including 21 obese and 11 healthy controls. The initial evaluation of the females included a general physical examination and laboratory tests. Small EVs (sEVs) were isolated from whole blood by serial centrifugation and ultracentrifugation, and nanoparticle analysis was used to determine the size and concentration of serum sEVs. miRNAs were extracted from sEVs enriched fraction and analyzed by real-time polymerase chain reaction. Obese female dogs with hypertriglyceridemia showed an increase in the sEVs concentration and in the expression of miR-132 and miR-26b in sEVs enriched fraction. No changes were observed in the group of obese female dogs with normal serum biochemical profile and in relation to miR-155 expression. These results suggest that obese female dogs with hypertriglyceridemia may present alterations in sEVs and in the expression of miRNAs related to lipid metabolism and adipogenesis.

A Physiological Approach to Inflammatory Markers in Obesity

Obesity is one of the most critical health problems all over the world; it is associated with metabolic dysfunction and overnutrition. Changes in the physiological function of adipose tissue, leading to altered secretion of adipocytokines, inflammatory mediators release, and chronic low-grade inflammation, are seen in obesity. Macrophages, neutrophils, CD4+ and CD8+ T cells, B cells, natural killer T (NKT) cells, eosinophils, mast cells, and adipocytes are involved in the inflammatory response that occurs during obesity. Various inflammatory markers are released from these cells. In this chapter, we will mention inflammatory mechanisms and markers of obesity.

Formic acid induces hypertension-related hemorrhage in hSSAOTG in mice and human

Hypertension is a confirmed risk factor for cerebral hemorrhage in humans. Which endogenous factor directly induces hypertension-related hemorrhage is unclear. In this study, 42 hemorrhagic patients with hypertension and hyperlipidemia and 42 age-matched healthy controls were enrolled. The contents of serum semicarbazide-sensitive amine oxidase (SSAO) and formic acid (FC, FC is a final product of SSAO through the oxidation of endogenous formaldehyde, which results from the enzymatic oxidative deamination of the SSAO substrate, methylamine) were examined in the patients after stroke. Hemorrhagic areas were quantified by computer tomography. In the animal study, hemorrhagic degree was assessed by hemotoxylin & eosin or tissue hemoglobin kits. The relationship between FC and blood pressure/hemorrhagic degree was examined in wild-type mice and hSSAO^TG mice fed with high-fat diets or high-fat and -salt diets. The results showed that the levels of serum FC were positively correlated with blood pressure and hemorrhagic areas in hemorrhagic patients. Transfection of microRNA-134 could enhance SSAO expression in human vascular smooth muscle cells. Consistently, after treatment with high-fat and -salt diets, hSSAO^TG mice exhibited higher levels of miR134 and FC, higher blood pressure, and more severe hemorrhage than wild-type mice. Interestingly, folic acid reduced hypertension and hemorrhage in hSSAO^TG mice fed with high-fat diets. These findings suggest that FC is a crucial endogenous factor for hypertension and hemorrhage.

Analysis of the miRNA expression from the adipose tissue surrounding the adrenal neoplasia

Background

Primary aldosteronism (PA) is characterized by several metabolic changes such as insulin resistance, metabolic syndrome, and adipose tissue (AT) inflammation. Mi(cro)RNAs (miRNAs) are a class of non-coding small RNA molecules known to be critical regulators in several cellular processes associated with AT dysfunction. The aim of this study was to evaluate the expression of some miRNAs in visceral and subcutaneous AT in patients undergoing adrenalectomy for aldosterone-secreting adrenal adenoma (APA) compared to the samples of AT obtained in patients undergoing adrenalectomy for non-functioning adrenal mass (NFA).

Methods

The quantitative expression of selected miRNA using real-time PCR was analyzed in surrounding adrenal neoplasia, peri-renal, and subcutaneous AT samples of 16 patients with adrenalectomy (11 patients with APA and 5 patients with NFA).

Results

Real-time PCR cycles for miRNA-132, miRNA-143, and miRNA-221 in fat surrounding adrenal neoplasia and in peri-adrenal AT were significantly higher in APA than in patients with NFA. Unlike patients with NFA, miRNA-132, miRNA-143, miRNA-221, and miRNA-26b were less expressed in surrounding adrenal neoplasia AT compared to subcutaneous AT in patients with APA.

Conclusion

This study, conducted on tissue expression of miRNAs, highlights the possible pathophysiological role of some miRNAs in determining the metabolic alterations in patients with PA.

Adipocyte differentiation between obese and lean conditions depends on changes in miRNA expression

Adipogenesis is the process by which precursor cells, preadipocytes (preACs), differentiate into adipocytes (ACs). Here, we investigated differentially expressed miRNAs (DEMs) between the two conditions to understand the regulatory role of miRNAs in altering adipogenesis-related mRNAs. A total of 812 and 748 DEMs were obtained in lean and obese conditions, respectively. The up- and downregulated DEMs were highly concordant with each other in both lean and obese conditions; however, DEMs related to adipogenesis in obese conditions were more strongly downregulated than DEMs related to adipogenesis in lean conditions. There were more obese-specific downregulated DEMs than lean-specific downregulated DEMs; in contrast, there were more lean-specific upregulated DEMs than obese-specific upregulated DEMs. Approximately 45% of DEMs were mapped to the list of miRNA-target mRNA pairs when DEMs were matched to the experimentally validated list of miRNA-target mRNA information of miRTarBase. Many of the target mRNAs were differentially expressed genes (DEGs) with functions in processes such as inflammatory responses and fat metabolism. In particular, a total of 25 miRNAs that target three upregulated adipogenesis-associated inflammatory genes (IL-6, TNF-α, and IL-1β) were commonly altered during adipogenesis. Taken together, our study reveals the types of adipogenesis-related miRNAs that are altered and the degree to which they influence healthy or pathogenic adipogenesis.

Changes in circulating microRNAs-99/100 and reductions of visceral and ectopic fat depots in response to lifestyle interventions: the CENTRAL trial

BACKGROUND

MicroRNAs (miRNAs) are short noncoding RNAs and important posttranscriptional regulators of gene expression. Adipose tissue is a major source of circulating miRNAs; adipose-related circulating miRNAs may regulate body fat distribution and glucose metabolism.

OBJECTIVES

We investigated how changes in adipose-related circulating microRNAs-99/100 (miR-99/100) in response to lifestyle interventions were associated with improved body fat distribution and reductions of diabetogenic ectopic fat depots among adults with abdominal obesity.

METHODS

This study included adults with abdominal obesity from an 18-mo diet and physical activity intervention trial. Circulating miR-99a-5p, miR-99b-5p, and miR-100-5p were measured at baseline and 18 mo; changes in these miRNAs in response to the interventions were evaluated. The primary outcomes were changes in abdominal adipose tissue [visceral (VAT), deep subcutaneous (DSAT), and superficial subcutaneous (SSAT) adipose tissue; cm2] (n = 144). The secondary outcomes were changes in ectopic fat accumulation in the liver (n = 141) and pancreas (n = 143).

RESULTS

Greater decreases in miR-100-5p were associated with more reductions of VAT (β ± SE per 1-SD decrease: -9.63 ± 3.13 cm2; P = 0.0025), DSAT (β ± SE: -5.48 ± 2.36 cm2; P = 0.0218), SSAT (β ± SE: -4.64 ± 1.68 cm2; P = 0.0067), and intrahepatic fat percentage (β ± SE: -1.54% ± 0.49%; P = 0.0023) after the interventions. Similarly, participants with greater decrease in miR-99a-5p had larger 18-mo reductions of VAT (β ± SE: -10.12 ± 3.31 cm2 per 1-SD decrease; P = 0.0027) and intrahepatic fat percentage (β ± SE: -1.28% ± 0.52%; P = 0.015). Further, decreases in circulating miR-99b-5p (β ± SE: per 1-SD decrease: -0.44% ± 0.21%; P = 0.038) and miR-100-5p (β ± SE: -0.50% ± 0.23%; P = 0.033) were associated with a decrease in pancreatic fat percentage, as well as improved glucose metabolism and insulin secretion at 18 mo.

CONCLUSIONS

Decreases in circulating miR-99-5p/100-5p expression induced by lifestyle interventions were related to improved body fat distribution and ectopic fat accumulation. Our study suggests that changes in circulating adipose-related miR-99-5p/100-5p may be linked to reducing diabetogenic fat depots in patients with abdominal obesity.This trial was registered at clinicaltrials.gov as NCT01530724.

Different expression of miRNA in the subcutaneous and visceral adipose tissue of obese subjects

Obesity is a pathology characterized by an excessive accumulation of adipose tissue and it is a condition associated with complex alterations affecting different organs and systems. Obesity has great influences on cardiovascular and respiratory morbidity and mortality and impairs the multiple aspects of metabolism. Since micro-RNAs (miRNAs) are thought to play a role in the regulation of various pathological processes, in this complex framework, the investigation of these classes of noncoding regulatory RNA seems to be promising. Selected group of obese subjects was recruited. We analysed the expression of seven miRNAs from obese adipose tissue supposed to have a role in the pathogenesis of cardiovascular and respiratory disease related to obesity and we compared it with the expression of the same miRNAs in a group of non-obese controls. In the current study what emerged is miR-27b and miR-483 significant down-regulation in subcutaneous adipose tissue from obese group compared with non-obese ones. For visceral adipose tissue, a significant decrease in miR-27b and miR-223 expression was observed in obese group. Moreover, a different expression of miR-26a and miR-338 in the obese group was found. Those findings could help the individuation of previously unknown key players in the development of different diseases usually associated with obesity, such as cardiovascular and pulmonary diseases.

Contributions of microRNAs to Peripheral Insulin Sensitivity

An extensive literature base combined with advances in sequencing technologies demonstrate microRNA levels correlate with various metabolic diseases. Mechanistic studies also establish microRNAs regulate central metabolic pathways and thus play vital roles in maintaining organismal energy balance and metabolic homeostasis. This review highlights research progress on the roles and regulation of microRNAs in the peripheral tissues that confer insulin sensitivity. We discuss sequencing technologies used to comprehensively define the target spectrum of microRNAs in metabolic disease that complement studies reporting physiologic roles for microRNAs in the regulation of glucose and lipid metabolism in animal models. We also discuss the emerging roles of exosomal microRNAs as endocrine signals to regulate lipid and carbohydrate metabolism.

MicroRNAs in Obesity-Associated Disorders: The Role of Exercise Training

Obesity is a worldwide epidemic affecting over 13% of the adult population and is defined by an excess of body fat that predisposes comorbidities. It is considered a multifactorial disease in which environmental and genetic factors interact, and it is a risk marker for cardiovascular disease. Lifestyle modifications remain the mainstay of treatment for obesity based on adequate diet and physical exercise. In addition, obesity is related to cardiovascular and skeletal muscle disorders, such as cardiac hypertrophy, microvascular rarefaction, and skeletal muscle atrophy. The discovery of obesity-involved molecular pathways is an important step to improve both the prevention and management of this disease. MicroRNAs (miRNAs) are a class of gene regulators which bind most commonly, but not exclusively, to the 3'-untranslated regions of messenger RNAs of protein-coding genes and negatively regulate their expression. Considerable effort has been made to identify miRNAs and target genes that predispose to obesity. Besides their intracellular function, recent studies have demonstrated that miRNAs can be exported or released by cells and circulate within the blood in a remarkably stable form. The discovery of circulating miRNAs opens up intriguing possibilities for the use of circulating miRNA patterns as biomarkers for obesity and cardiovascular diseases. The aim of this review is to provide an overview of the recent discoveries of the role played by miRNAs in the obese phenotype and associated comorbidities. Furthermore, we will discuss the role of exercise training on regulating miRNAs, indicating the mechanisms related to these alterations.

SNPs in miRNAs and Target Sequences: Role in Cancer and Diabetes

miRNAs are fascinating molecular players for gene regulation as individual miRNA can control multiple targets and a single target can be regulated by multiple miRNAs. Loss of miRNA regulated gene expression is often reported to be implicated in various human diseases like diabetes and cancer. Recently, geneticists across the world started reporting single nucleotide polymorphism (SNPs) in seed sequences of miRNAs. Similarly, SNPs are also reported in various target sequences of these miRNAs. Both the scenarios lead to dysregulated gene expression which may result in the progression of diseases. In the present paper, we explore SNPs in various miRNAs and their target sequences reported in various human cancers as well as diabetes. Similarly, we also present evidence of these mutations in various other human diseases.

MiR-17-5p Inhibits TXNIP/NLRP3 Inflammasome Pathway and Suppresses Pancreatic β-Cell Pyroptosis in Diabetic Mice

Objective: Diabetes mellitus is a chronic progressive inflammatory metabolic disease with pancreatic β-cells dysfunction. The present study aimed to investigate whether miR-17-5p plays a protective effect on pancreatic β-cells function in diabetes mellitus (DM) mice and dissect the underlying mechanism.

Methods: C57BL/6J mice were randomly divided into control, DM, DM + Lentivirus negative control (LV-NC), and DM + Lenti-OE™ miR-17-5p (LV-miR-17-5) groups. DM was established by feeding a high-fat diet and intraperitoneal injection with streptozotocin (STZ) in mice. Blood glucose and glucose tolerance in circulation were measured. Meanwhile, the activation of nod-like receptor protein 3 (NLRP3) inflammasome, pancreas pyroptosis, and the expression of miR-17-5p and thioredoxin-interacting protein (TXNIP) were detected in the pancreas of DM mice. Pancreatic β-cell line INS-1 subjected to different concentrations of glucose was used in in vitro experiments.

Results: Compared with control mice, glucose tolerance deficit, elevated blood glucose level, and decreased pancreatic islet size, were presented in DM mice, which was associated with a downregulation of miR-17-5p. Importantly, exogenous miR-17-5p alleviated pancreas injury, and consequently improved glucose tolerance and decreased blood glucose in DM mice. In vitro experiments showed that high glucose decreased miR-17-5p expression and impaired insulin secretion in INS-1 cells. Mechanistically, miR-17-5p inhibited the expression of TXNIP and NLRP3 inflammasome activation, and thus decreased pancreatic β-cell pyroptosis.

Conclusion: Our results demonstrated that miR-17-5p improves glucose tolerance, and pancreatic β-cell function and inhibits TXNIP/NLRP3 inflammasome pathway-related pyroptosis in DM mice.

microRNAs in Human Adipose Tissue Physiology and Dysfunction

In recent years, there has been a large amount of evidence on the role of microRNA (miRNA) in regulating adipose tissue physiology. Indeed, miRNAs control critical steps in adipocyte differentiation, proliferation and browning, as well as lipolysis, lipogenesis and adipokine secretion. Overnutrition leads to a significant change in the adipocyte miRNOME, resulting in adipose tissue dysfunction. Moreover, via secreted mediators, dysfunctional adipocytes may impair the function of other organs and tissues. However, given their potential to control cell and whole-body energy expenditure, miRNAs also represent critical therapeutic targets for treating obesity and related metabolic complications. This review attempts to integrate present concepts on the role miRNAs play in adipose tissue physiology and obesity-related dysfunction and data from pre-clinical and clinical studies on the diagnostic or therapeutic potential of miRNA in obesity and its related complications.

miR-146a-5p modulates cellular senescence and apoptosis in visceral adipose tissue of long-lived Ames dwarf mice and in cultured pre-adipocytes

MicroRNAs (miRNAs) are potent regulators of multiple biological processes. Previous studies have demonstrated that miR-146a-5p increases in normal mice during aging, while long-living Ames dwarf (df/df) mice maintain youthful levels of this miRNA. The aim of this study was to elucidate the involvement of miR-146a-5p in modulating cellular senescence and apoptosis in visceral adipose tissue of df/df mice and cultured pre-adipocytes. To test the effects of miR-146a-5p overexpression on visceral adipose tissue, wild-type, and df/df mice, were treated with miRNA-negative control-base and df/df were transfected with 4 or 8 µg/g of a miR-146a-5p mimetic, respectively. Effects of miR-146a-5p overexpression were also evaluated in 3T3-L1 cells cultured under high and normal glucose conditions. Treatment with miR-146a-5p mimetic increased cellular senescence and inflammation and decreased pro-apoptotic factors in visceral adipose tissue of df/df mice. The miR-146a-5p mimetic induced similar effects in 3T3-L1 cells cultivated at normal but not high glucose levels. Importantly, 3T3-L1 HG cells in high glucose conditions showed significantly higher expression of miR-146a-5p than 3T3-L1 grown in normal glucose conditions. These results indicate that miR-146a-5p can be a marker for cellular senescence. This miRNA represents one of the significant SASP factors that if not precisely regulated, can accentuate inflammatory responses and stimulate senescence in surrounding non-senescent cells. The role of miR-146a-5p is different in healthy versus stressed cells, suggesting potential effects of this miRNA depend on overall organismal health, aging, and metabolic state.

Relationship Between Coronary Atheroma, Epicardial Adipose Tissue Inflammation, and Adipocyte Differentiation Across the Human Myocardial Bridge

Background Inflammation in epicardial adipose tissue (EAT) may contribute to coronary atherosclerosis. Myocardial bridge is a congenital anomaly in which the left anterior descending coronary artery takes a "tunneled" course under a bridge of myocardium: while atherosclerosis develops in the proximal left anterior descending coronary artery, the bridged portion is spared, highlighting the possibility that geographic separation from inflamed EAT is protective. We tested the hypothesis that inflammation in EAT was related to atherosclerosis by comparing EAT from proximal and bridge depots in individuals with myocardial bridge and varying degrees of atherosclerotic plaque. Methods and Results Maximal plaque burden was quantified by intravascular ultrasound, and inflammation was quantified by pericoronary EAT signal attenuation (pericoronary adipose tissue attenuation) from cardiac computed tomography scans. EAT overlying the proximal left anterior descending coronary artery and myocardial bridge was harvested for measurement of mRNA and microRNA (miRNA) using custom chips by Nanostring; inflammatory cytokines were measured in tissue culture supernatants. Pericoronary adipose tissue attenuation was increased, indicating inflammation, in proximal versus bridge EAT, in proportion to atherosclerotic plaque. Individuals with moderate-high versus low plaque burden exhibited greater expression of inflammation and hypoxia genes, and lower expression of adipogenesis genes. Comparison of gene expression in proximal versus bridge depots revealed differences only in participants with moderate-high plaque: inflammation was higher in proximal and adipogenesis lower in bridge EAT. Secreted inflammatory cytokines tended to be higher in proximal EAT. Hypoxia-inducible factor 1a was highly associated with inflammatory gene expression. Seven miRNAs were differentially expressed by depot: 3192-5P, 518D-3P, and 532-5P were upregulated in proximal EAT, whereas miR 630, 575, 16-5P, and 320E were upregulated in bridge EAT. miR 630 correlated directly with plaque burden and inversely with adipogenesis genes. miR 3192-5P, 518D-3P, and 532-5P correlated inversely with hypoxia/oxidative stress, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PCG1a), adipogenesis, and angiogenesis genes. Conclusions Inflammation is specifically elevated in EAT overlying atherosclerotic plaque, suggesting that EAT inflammation is caused by atherogenic molecular signals, including hypoxia-inducible factor 1a and/or miRNAs in an "inside-to-out" relationship. Adipogenesis was suppressed in the bridge EAT, but only in the presence of atherosclerotic plaque, supporting cross talk between the vasculature and EAT. miR 630 in EAT, expressed differentially according to burden of atherosclerotic plaque, and 3 other miRNAs appear to inhibit key genes related to adipogenesis, angiogenesis, hypoxia/oxidative stress, and thermogenesis in EAT, highlighting a role for miRNA in mediating cross talk between the coronary vasculature and EAT.

The Metabolic Significance of Intermuscular Adipose Tissue: Is IMAT a Friend or a Foe to Metabolic Health?

Adipose tissues are not homogeneous and show site-specific properties. An elusive and understudied adipose tissue depot, most likely due to its limited accessibility, is the intermuscular adipose tissue (IMAT) depot. Adipose tissue is a pliable organ with the ability to adapt to its physiological context, yet whether that adaptation is harmful or beneficial in the IMAT depot remains to be explored in humans. Potential reasons for IMAT accumulation in humans being deleterious or beneficial include 1) sex and related circulating hormone levels, 2) race and ethnicity, and 3) lifestyle factors (e.g., diet and physical activity level). IMAT quantity per se may not be the driving factor in the etiology of insulin resistance and type 2 diabetes, but rather the quality of the IMAT itself is the true puppeteer. Adipose tissue quality likely influences its secreted factors, which are also likely to influence metabolism of surrounding tissues. The advent of molecular assessments such as transcriptome sequencing (RNAseq), assay for transposase-accessible chromatin using sequencing (ATACseq), and DNA methylation at the single-cell and single-nucleus levels, as well as the potential for ultrasound-guided biopsies specifically for IMAT, will permit more sophisticated investigations of human IMAT and dramatically advance our understanding of this enigmatic adipose tissue.

Molecular Aspects of Lifestyle and Environmental Effects in Patients With Diabetes: JACC Focus Seminar

Diabetes is characterized as an integrated condition of dysregulated metabolism across multiple tissues, with well-established consequences on the cardiovascular system. Recent advances in precision phenotyping in biofluids and tissues in large human observational and interventional studies have afforded a unique opportunity to translate seminal findings in models and cellular systems to patients at risk for diabetes and its complications. Specifically, techniques to assay metabolites, proteins, and transcripts, alongside more recent assessment of the gut microbiome, underscore the complexity of diabetes in patients, suggesting avenues for precision phenotyping of risk, response to intervention, and potentially novel therapies. In addition, the influence of external factors and inputs (eg, activity, diet, medical therapies) on each domain of molecular characterization has gained prominence toward better understanding their role in prevention. Here, the authors provide a broad overview of the role of several of these molecular domains in human translational investigation in diabetes.

Non-Coding RNAs: Novel Players in Insulin Resistance and Related Diseases

The rising prevalence of metabolic diseases related to insulin resistance (IR) have stressed the urgent need of accurate and applicable tools for early diagnosis and treatment. In the last decade, non-coding RNAs (ncRNAs) have gained growing interest because of their potential role in IR modulation. NcRNAs are variable-length transcripts which are not translated into proteins but are involved in gene expression regulation. Thanks to their stability and easy detection in biological fluids, ncRNAs have been investigated as promising diagnostic and therapeutic markers in metabolic diseases, such as type 2 diabetes mellitus (T2D), obesity and non-alcoholic fatty liver disease (NAFLD). Here we review the emerging role of ncRNAs in the development of IR and related diseases such as obesity, T2D and NAFLD, and summarize current evidence concerning their potential clinical application.

Functional Role of miR-155 in the Pathogenesis of Diabetes Mellitus and Its Complications

Substantial evidence indicates that microRNA-155 (miR-155) plays a crucial role in the pathogenesis of diabetes mellitus (DM) and its complications. A number of clinical studies reported low serum levels of miR-155 in patients with type 2 diabetes (T2D). Preclinical studies revealed that miR-155 partakes in the phenotypic switch of cells within the islets of Langerhans under metabolic stress. Moreover, miR-155 was shown to regulate insulin sensitivity in liver, adipose tissue, and skeletal muscle. Dysregulation of miR-155 expression was also shown to predict the development of nephropathy, neuropathy, and retinopathy in DM. Here, we systematically describe the reports investigating the role of miR-155 in DM and its complications. We also discuss the recent results from in vivo and in vitro models of type 1 diabetes (T1D) and T2D, discussing the differences between clinical and preclinical studies and shedding light on the molecular pathways mediated by miR-155 in different tissues affected by DM.

The Role of miR-155 in Nutrition: Modulating Cancer-Associated Inflammation

Nutrition plays an important role in overall human health. Although there is no direct evidence supporting the direct involvement of nutrition in curing disease, for some diseases, good nutrition contributes to disease prevention and our overall well-being, including energy level, optimum internal function, and strength of the immune system. Lately, other major, but more silent players are reported to participate in the body’s response to ingested nutrients, as they are involved in different physiological and pathological processes. Furthermore, the genetic profile of an individual is highly critical in regulating these processes and their interactions. In particular, miR-155, a non-coding microRNA, is reported to be highly correlated with such nutritional processes. In fact, miR-155 is involved in the orchestration of various biological processes such as cellular signaling, immune regulation, metabolism, nutritional responses, inflammation, and carcinogenesis. Thus, this review aims to highlight those critical aspects of the influence of dietary components on gene expression, primarily on miR-155 and its role in modulating cancer-associated processes.

Dysmetabolic adipose tissue in obesity: morphological and functional characteristics of adipose stem cells and mature adipocytes in healthy and unhealthy obese subjects

The way by which subcutaneous adipose tissue (SAT) expands and undergoes remodeling by storing excess lipids through expansion of adipocytes (hypertrophy) or recruitment of new precursor cells (hyperplasia) impacts the risk of developing cardiometabolic and respiratory diseases. In unhealthy obese subjects, insulin resistance, type 2 diabetes, hypertension, and obstructive sleep apnoea are typically associated with pathologic SAT remodeling characterized by adipocyte hypertrophy, as well as chronic inflammation, hypoxia, increased visceral adipose tissue (VAT), and fatty liver. In contrast, metabolically healthy obese individuals are generally associated with SAT development characterized by the presence of smaller and numerous mature adipocytes, and a lower degree of VAT inflammation and ectopic fat accumulation. The remodeling of SAT and VAT is under genetic regulation and influenced by inherent depot-specific differences of adipose tissue-derived stem cells (ASCs). ASCs have multiple functions such as cell renewal, adipogenic capacity, and angiogenic properties, and secrete a variety of bioactive molecules involved in vascular and extracellular matrix remodeling. Understanding the mechanisms regulating the proliferative and adipogenic capacity of ASCs from SAT and VAT in response to excess calorie intake has become a focus of interest over recent decades. Here, we summarize current knowledge about the biological mechanisms able to foster or impair the recruitment and adipogenic differentiation of ASCs during SAT and VAT development, which regulate body fat distribution and favorable or unfavorable metabolic responses.