ApoE attenuates atherosclerosis via miR-146a

Diet-dependent sex differences in the response to vertical sleeve gastrectomy

Nearly 80% of patients that receive bariatric surgery are women, yet mechanistic preclinical studies have focused on males. The goal of this study was to determine the metabolic impact of diet- and surgery-induced weight loss in males, females, and ovariectomized females. All mice were fed a 60% high-fat diet (HFD) before undergoing either vertical sleeve gastrectomy (VSG) or sham surgery. Mice either remained on an HFD or were switched to a standard chow diet postsurgically. When maintained on an HFD, males and females decreased fat mass and improved oral glucose tolerance after VSG. After dietary intervention, additional adiposity was lost in both surgical groups. Ovariectomized females showed a blunted decrease in fat mass on an HFD, but lost significant adiposity after dietary intervention. Energy expenditure was impacted by dietary and not surgical intervention across all groups. Males decreased hepatic triglyceride levels after VSG, which was further decreased after dietary intervention. Intact and ovariectomized females had a blunted decrease in hepatic triglycerides after VSG, but a significant decrease after dietary intervention. The more pronounced effect of VSG on hepatic lipids in males is strongly associated with changes in hepatic expression of genes and microRNAs previously linked to hepatic lipid regulation and systemic energy homeostasis. These data highlight the importance of postsurgical diet on metabolic outcomes across sexes. Furthermore, these data suggest the impact of VSG on hepatic triglycerides is diet-dependent in females and support the hypothesis that males and females achieve similar metabolic outcome, at least within the liver, via distinct mechanisms.NEW & NOTEWORTHY These data highlight the interaction of postsurgical diet after bariatric surgery on metabolic outcomes across sexes. These data suggest the impact of VSG on hepatic triglycerides is diet-dependent in females and support the hypothesis that males and females achieve similar metabolic outcome, at least within the liver, via distinct mechanisms.

miR-146a in Cardiovascular Diseases and Sepsis: An Additional Burden in the Inflammatory Balance?

The new concept of thrombosis associated with an inflammatory process is called thromboinflammation. Indeed, both thrombosis and inflammation interplay one with the other in a feed forward manner amplifying the whole process. This pathological reaction in response to a wide variety of sterile or non-sterile stimuli eventually causes acute organ damage. In this context, neutrophils, mainly involved in eliminating pathogens as an early barrier to infection, form neutrophil extracellular traps (NETs) that are antimicrobial structures responsible of deleterious side effects such as thrombotic complications. Although NETosis mechanisms are being unraveled, there are still many regulatory elements that have to be discovered. Micro-ribonucleic acids (miRNAs) are important modulators of gene expression implicated in human pathophysiology almost two decades ago. Among the different miRNAs implicated in inflammation, miR-146a is of special interest because: (1) it regulates among others, Toll-like receptors/nuclear factor-κB axis which is of paramount importance in inflammatory processes, (2) it regulates the formation of NETs by modifying their aging phenotype, and (3) it has expression levels that may decrease among individuals up to 50%, controlled in part by the presence of several polymorphisms. In this article, we will review the main characteristics of miR-146a biology. In addition, we will detail how miR-146a is implicated in the development of two paradigmatic diseases in which thrombosis and inflammation interact, cardiovascular diseases and sepsis, and their association with the presence of miR-146a polymorphisms and the use of miR-146a as a marker of cardiovascular diseases and sepsis.

MicroRNA Mediated Cardioprotection - Is There a Path to Clinical Translation?

In the past 20 years, there have been several approaches to achieve cardioprotection or cardiac regeneration using a vast variety of cell therapies and remote ischemic pre-conditioning (RIPC). To date, substantial proof that either cell therapy or RIPC has the potential for clinically relevant cardiac repair or regeneration of cardiac tissue is still pending. Preclinical trials indicate that the secretome of cells in situ (during RIPC) as well as of transplanted cells may exhibit cardioprotective properties in the acute setting of cardiac injury. The secretome generally consists of cell-specific cytokines and extracellular vesicles (EVs) containing microRNAs (miRNAs). It is currently hypothesized that a subset of known miRNAs play a crucial part in the facilitation of cardioprotective effects. miRNAs are small non-coding RNA molecules that inhibit post-transcriptional translation of messenger RNAs (mRNAs) and play an important role in gene translation regulation. It is also known that one miRNAs usually targets multiple mRNAs. This makes predictability of pharmacokinetics and mechanism of action very difficult and could in part explain the inferior performance of various progenitor cells in clinical studies. Identification of miRNAs involved in cardioprotection and remodeling, the composition of miRNA profiles, and the exact mechanism of action are important to the design of future cell-based but also cell-free cardioprotective therapeutics. This review will give a description of miRNA with cardioprotective properties and a current overview on known mechanism of action and potential missing links. Additionally, we will give an outlook on the potential for clinical translation of miRNAs in the setting of myocardial infarction and heart failure.

Genetics of Human Longevity Within an Eco-Evolutionary Nature-Nurture Framework

Human longevity is a complex trait, and to disentangle its basis has a great theoretical and practical consequences for biomedicine. The genetics of human longevity is still poorly understood despite several investigations that used different strategies and protocols. Here, we argue that such rather disappointing harvest is largely because of the extraordinary complexity of the longevity phenotype in humans. The capability to reach the extreme decades of human lifespan seems to be the result of an intriguing mixture of gene-environment interactions. Accordingly, the genetics of human longevity is here described as a highly context-dependent phenomenon, within a new integrated, ecological, and evolutionary perspective, and is presented as a dynamic process, both historically and individually. The available literature has been scrutinized within this perspective, paying particular attention to factors (sex, individual biography, family, population ancestry, social structure, economic status, and education, among others) that have been relatively neglected. The strength and limitations of the most powerful and used tools, such as genome-wide association study and whole-genome sequencing, have been discussed, focusing on prominently emerged genes and regions, such as apolipoprotein E, Forkhead box O3, interleukin 6, insulin-like growth factor-1, chromosome 9p21, 5q33.3, and somatic mutations among others. The major results of this approach suggest that (1) the genetics of longevity is highly population specific; (2) small-effect alleles, pleiotropy, and the complex allele timing likely play a major role; (3) genetic risk factors are age specific and need to be integrated in the light of the geroscience perspective; (4) a close relationship between genetics of longevity and genetics of age-related diseases (especially cardiovascular diseases) do exist. Finally, the urgent need of a global approach to the largely unexplored interactions between the 3 genetics of human body, that is, nuclear, mitochondrial, and microbiomes, is stressed. We surmise that the comprehensive approach here presented will help in increasing the above-mentioned harvest.

Downregulation of miR-34a promotes endothelial cell growth and suppresses apoptosis in atherosclerosis by regulating Bcl-2

Several miRNAs have been demonstrated to be involved in endothelial dysfunction during atherosclerosis (AS). However, the detailed roles and underlying mechanisms of miR-34a in AS-associated endothelial cell apoptosis are far from being addressed. Apolipoprotein E-deficient (ApoE^-/-) mice fed with high-fat diet (HFD) were used as in vivo model of AS. Oxidized low-density lipoprotein (ox-LDL)-treated human aortic endothelial cells (HAECs) were applied as in vitro model of AS. The effects of miR-34a on atherosclerotic lesions were evaluated by hematoxylin-eosin (HE) and Oil Red O staining. Pecam-1⁺ endothelial cells were isolated from the aortic arch with flow cytometry. qRT-PCR and western blot were employed to measure gene and protein expression. The effects of miR-34a on cell viability, cell cycle distribution, and apoptosis were assessed by Cell counting kit (CCK)-8 and flow cytometry analysis. The relationship between miR-34a and Bcl-2 was confirmed by online softwares, luciferase reporter assay, and RNA immunoprecipitation (RIP). miR-34a was upregulated in HFD-induced ApoE^-/- mice and ox-LDL-treated HAECs. Anti-miR-34a decreased atherosclerotic lesions and inhibited Pecam-1⁺ endothelial cells apoptosis in HFD-induced ApoE^-/- mice. Moreover, anti-miR-34a significantly promoted cell viability, alleviated cell cycle arrest, and restrained apoptosis in ox-LDL-treated HAECs. Furthermore, Bcl-2 was identified as a target of miR-34a, and miR-34a inhibited Bcl-2 expression via binding to its 3'UTR. Rescue experiments demonstrated that Bcl-2 overexpression dramatically reversed miR-34a-mediated inhibition of cell growth and promotion of apoptosis in ox-LDL-exposed HAECs. Depletion of miR-34a facilitated endothelial cell growth and blocked apoptosis in AS by upregulating Bcl-2, offering a promising avenue for AS therapy.

MicroRNA-31 promotes arterial smooth muscle cell proliferation and migration by targeting mitofusin-2 in arteriosclerosis obliterans of the lower extremitie

MicroRNA (miR)-31 serves a key role in various biological processes, including tumor development, angiogenesis and inflammation. Whether miR-31 is involved in the pathological processes of arteriosclerosis obliterans (ASO) remains to be elucidated, as does the mechanism of miR-31 regulation of arterial smooth muscle cells (ASMCs). In the present study, miR-31 expression was detected by reverse transcription-quantitative polymerase chain reaction and in situ hybridization, and was significantly upregulated in human ASO arterial walls compared with normal arterial walls (P<0.001). In addition, miR-31 proliferation was detected by Cell Counting Kit-8 and EdU assays; proliferation was significantly promoted in platelet-derived growth factor (PDGF)-BB-induced human ASMCs (HASMCs) (P<0.001). miR-31 migration was detected by transwell and wound closure assays, and was revealed to be promoted in PDGF-BB-induced HASMCs (P<0.001). Lastly, HASMCs were transfected with miR-31 mimics and inhibitors, and negative controls. A dual-luciferase reporter assay was performed to verify that mitofusin-2 (MFN2) was a direct target of miR-31 and that MFN2 expression was significantly downregulated by miR-31 at a post-transcriptional level in HASMCs as detected by western blotting (P<0.01). These findings suggest that miR-31 is able to promote the proliferation and migration of HASMCs, at least in part, by targeting MFN2. The results of the present study provide novel insight into the underlying mechanisms and roles of miR-31/MFN2 in the pathology of ASO, which may offer a potential therapeutic target for the treatment of ASO.

MicroRNA-210 induces endothelial cell apoptosis by directly targeting PDK1 in the setting of atherosclerosis

Background

Atherosclerosis is a chronically inflammatory disease and one of the leading causes of deaths worldwide. Endothelial cell apoptosis plays a crucial role in its development. Several microRNAs (miRNAs) are reportedly involved in atherosclerotic plaque formation, including miRNA-210 (miR-210). However, the underlying mechanism of its role in endothelial cell apoptosis during atherosclerosis is still largely unknown.

Methods

A mouse model with atherosclerosis induced by a high-fat diet (HFD) was built in ApoE (-/-) mice. The levels of endothelial cell apoptosis were determined via flow cytometry. The expressions of miR-210 and PDK1 in purified CD31+ endothelial cells from mouse aorta were measured via RT-qPCR and western blot. Binding between miR-210 and the 3′-untranslated region (UTR) of PDK1 mRNA was predicted using bioinformatics analyses and confirmed with a dual luciferase reporter assay. The effects of miR-210 were further analyzed in an in vitro model using human aortic endothelial cells (HAECs) treated with oxidized low-density lipoprotein (ox-LDL).

Results

We found that the HFD mice developed atherosclerosis in 12 weeks and had a significantly higher percentage of endothelial cell apoptosis. The upregulated level of miR-210 in the HFD mice and HAECs inversely correlated with the level of PDK1. Inhibiting miR-210 expression significantly reduced HAEC apoptosis, as evidenced by the results of the MTT and flow cytometry experiments. Further analysis identified PDK1 as the target of miR-210 and showed that PDK1 overexpression reversed the pro-apoptotic effect of miR-210 through mediation of the P13K/Akt/mTOR pathways.

Conclusion

Our study suggests a novel role for miR-210 in the progression of atherosclerosis through the regulation of endothelial apoptosis. This indicates that miR-210 might have potential in treatment of atherosclerosis.

Aryl hydrocarbon receptor (AhR)-dependent regulation of pulmonary miRNA by chronic cigarette smoke exposure

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor historically known for its toxic responses to man-made pollutants such as dioxin. More recently, the AhR has emerged as a suppressor of inflammation, oxidative stress and apoptosis from cigarette smoke by mechanisms that may involve the regulation of microRNA. However, little is known about the AhR regulation of miRNA expression in the lung in response to inhaled toxicants. Therefore, we exposed Ahr^−/− and Ahr^+/− mice to cigarette smoke for 4 weeks and evaluated lung miRNA expression by PCR array. There was a dramatic regulation of lung miRNA by the AhR in the absence of exogenous ligand. In response to cigarette smoke, there were more up-regulated miRNA in Ahr^−/− mice compared to Ahr^+/− mice, including the cancer-associated miRNA miR-96. There was no significant change in the expression of the AhR regulated proteins HuR and cyclooxygenase-2 (COX-2). There were significant increases in the anti-oxidant gene sulfiredoxin 1 (Srxn1) and FOXO3a- predicted targets of miR-96. Collectively, these data support a prominent role for the AhR in regulating lung miRNA expression. Further studies to elucidate a role for these miRNA may further uncover novel biological function for the AhR in respiratory health and disease.

miRNA-93-5p and other miRNAs as predictors of coronary artery disease and STEMI

BACKGROUND

MicroRNAs (miRNAs), small non-coding RNAs, have been implicated as regulators of all mediators of atherosclerosis, and some reports have suggested increased levels in coronary artery disease (CAD) and acute myocardial infarction (AMI). However, the potential of miRNAs as biomarkers or predictors of disease remains to be established.

METHODS

We designed a study comprising 150 patients (50 Control, 50 Stable CAD, and 50 ST Elevation Myocardial Infarction (STEMI)), and measured plasma miRNAs in each. We then determined the ability of differential miRNAs, adjusting for Framingham Heart Study (FHS) risk factors, to discriminate between CAD vs Control, and STEMI vs Control.

RESULTS

Three miRNAs (miR15a-5p, miR16-5p, and miR93-5p) were significantly increased in Stable CAD vs Control groups and one (miR146a-5p) was significantly decreased in Stable CAD vs Control. One miRNA - miR499a-5p - was significantly increased in the STEMI group compared to Controls. After adjustment for FHS risk factors, miR93-5p levels remained an independent predictor of the presence of CAD (Odds Ratio [OR]=8.76, P=0.002). All 4 miRNAs improved discriminatory power for CAD over FHS alone in ROC analysis. Similarly, after adjustment for risk factors miR499-5p remained an independent predictor of STEMI (OR=3.03, P=0.001) and improved discriminatory power for STEMI in ROC analyses.

CONCLUSION

We identified 4 miRNAs that were differentially expressed among stable CAD and control patients, and 1 miRNA that was elevated in STEMI patients vs controls. MiR93-5p was the strongest predictor of CAD after adjustment for traditional risk factors, suggesting potential diagnostic utility.

Tiny Shuttles for Information Transfer: Exosomes in Cardiac Health and Disease

Intercellular communication mediated by exosomes, nano-sized extracellular vesicles, is crucial for preserving vascular integrity and in the development of cardiovascular and other diseases. As natural carriers of signal molecules, exosomes released from sources such as blood cells, endothelial cells, immune cells, smooth muscle cells, etc., can modify a multitude of cellular bioactivities. They do so by shuttling lipids, proteins, and nucleic acids between donor and recipient cells while circulating in body fluids and in the extracellular space. A recent surge of interest in the field of exosomal biology is in part due to the recognition that the molecules they carry can act as facilitators of both pathogenesis but can also initiate protective and rescue signaling. This mini-review describes current knowledge on exosome function in health and disease including cardiovascular disease.

Apolipoprotein E Epsilon 4 Enhances the Association between the rs2910164 Polymorphism of miR-146a and Risk of Atherosclerotic Cerebral Infarction

AIM

To analyse the relationship between two potentially functional single-nucleotide polymorphisms (SNPs) of the miR-146a gene (rs2910164 and rs57095329) and the risk of atherosclerotic cerebral infarction (ACI).

METHODS

A total of 297 patients with ACI and 300 matched healthy individuals were enrolled in the study. The miR-146a polymorphism was detected using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

A significant difference in the C allele frequency at rs2910164 (p=0.028) was noted between patients with ACI and control subjects. In contrast, the genotype and allele frequencies of rs57095329 were not statistically associated with ACI. In addition, the decreased expression of miR-146a was significantly more frequent in ACI patients who were ApoEε4 (＋) carriers (p=0.0233), and rs2910164 G＞C was intimately associated with the ApoEε4-containing genotype in patients compared with the ApoEε4 (－) carriers (p=0.0323).

CONCLUSIONS

Our findings indicated that the C allele of rs2910164 miR-146a is an important risk factor for ACI, and ApoEε4 may function through attenuating miR-146a expression to enhance ACI susceptibility. This study provides new information about the possible relationship between miR-146a and ApoEε4 in the development of ACI, with potentially important therapeutic implications.

miR-223 Inhibits Lipid Deposition and Inflammation by Suppressing Toll-Like Receptor 4 Signaling in Macrophages

Atherosclerosis and its complications rank as the leading cause of death with the hallmarks of lipid deposition and inflammatory response. MicroRNAs (miRNAs) have recently garnered increasing interests in cardiovascular disease. In this study, we investigated the function of miR-223 and the underlying mechanism in atherosclerosis. In the atherosclerotic ApoE^−/− mice models, an obvious increase of miR-223 was observed in aortic atherosclerotic lesions. In lipopolysaccharide (LPS) activated macrophages, its expression was decreased. The miR-223 overexpression significantly attenuated macrophage foam cell formation, lipid accumulation and pro-inflammatory cytokine production, which were reversed by anti-miR-223 inhibitor transfection. Mechanism assay corroborated that miR-223 negatively regulated the activation of the toll-like receptor 4 (TLR4)-nuclear factor-κB (NF-κB) pathway. Pretreatment with a specific inhibitor of NF-κB (pyrrolidinedithiocarbamate, PDTC) strikingly abrogated miR-223 silence-induced lipid deposition and inflammatory cytokine production. Furthermore, PI3K/AKT was activated by miR-223 up-regulation. Pretreatment with PI3K/AKT inhibitor LY294002 strikingly ameliorated the inhibitory effects of miR-223 on the activation of TLR4 and p65, concomitant with the increase in lipid deposition and inflammatory cytokine production. Together, these data indicate that miR-223 up-regulation might abrogate the development of atherosclerosis by blocking TLR4 signaling through activation of the PI3K/AKT pathway, and provides a promising therapeutic avenue for the treatment of atherosclerosis.

Role and Function of MicroRNAs in Extracellular Vesicles in Cardiovascular Biology

Intercellular communication mediated by extracellular vesicles is crucial for preserving vascular integrity and in the development of cardiovascular disease. Extracellular vesicles consist of apoptotic bodies, microvesicles, and exosomes that can be found in almost every fluid compartment of the body like blood, saliva, and urine. In the recent years, a lot of reports came up suggesting that major cardiovascular and metabolic pathologies like atherogenesis, heart failure, or diabetes are highly influenced by transfer of microRNAs via extracellular vesicles leading to altered protein expression and phenotypes of recipient cells. The following review will summarize the fast developing field of intercellular signaling in cardiovascular biology by microRNA-containing extracellular vesicles.