The long noncoding RNA H19 is a novel regulator of SMC survival in abdominal aortic aneurysm development and progression. Inhibition of H19 expression might serve as a novel molecular therapeutic target for aortic aneurysm disease.

The human genome encodes thousands of long non-coding RNAs (lncRNAs), the majority of which are poorly conserved and uncharacterized. Here we identify a primate-specific lncRNA ( CHROME ), elevated in the plasma and atherosclerotic plaques of individuals with coronary artery disease, that regulates cellular and systemic cholesterol homeostasis. LncRNA CHROME expression is influenced by dietary and cellular cholesterol via the sterol-activated liver X receptor transcription factors, which control genes mediating responses to cholesterol overload. Using gain- and loss-of-function approaches, we show that CHROME promotes cholesterol efflux and HDL biogenesis by curbing the actions of a set of functionally related microRNAs that repress genes in those pathways. CHROME knockdown in human hepatocytes and macrophages increases levels of miR-27b, miR-33a, miR-33b and miR-128, thereby reducing expression of their overlapping target gene networks and associated biologic functions. In particular, cells lacking CHROME show reduced expression of ABCA1, which regulates cholesterol efflux and nascent HDL particle formation. Collectively, our findings identify CHROME as a central component of the non-coding RNA circuitry controlling cholesterol homeostasis in humans.

Objective Despite advances in stent technology for vascular interventions, in-stent restenosis (ISR) due to myointimal hyperplasia (MH) remains a major complication. Approach and Results We investigated the regulatory role of microRNAs in MH/ISR, utilizing a humanized animal model in which balloon-injured human internal mammary arteries (IMAs) with or without stenting were transplanted into RNU rats, followed by microRNA profiling. miR-21 was the only significantly up-regulated candidate. In addition, miR-21 expression was increased in human tissue samples from patients with ISR compared to coronary artery disease specimen. We systemically repressed miR-21 via intravenous FAM-tagged-LNA-anti-miR-21 (anti-21) in our humanized MH-model. As expected, suppression of vascular miR-21 correlated dose-dependently with reduced luminal obliteration. Further, anti-21 did not impede re-endothelialization. However, systemic anti-miR-21 had substantial off-target effects, lowering miR-21 expression in liver, heart, lung, and kidney with concomitant increased serum creatinine levels. We therefore assessed the feasibility of local miR-21 suppression using anti-21-coated stents. Compared to bare metal stents, anti-21-coated stents effectively reduced ISR, while no significant off-target effects could be observed. Conclusion This is the first study to demonstrate the efficacy of an anti-miR-coated stent for the reduction of ISR.

Stroke is the second most common cause of death 2 and major cause of disability worldwide, 2 with survivors often depending on lifelong care. Carotid stenosis is the second most common predecessor of ischemic stroke, 3 and carotid endarterectomy (CEA; and to a lesser extent carotid artery stenting) are accepted as secondary, but also primary preventive therapy. 2,4,5 With new imaging techniques, vulnerable plaques at risk of rupture can be identified with increasing accuracy, 6 but in the majority of cases, the perioperative surgical risk of ≈3% still outweighs the risk of plaque rupture in asymptomatic carotid stenosis carriers.7 As a result, CEA and carotid artery stenting are currently unfavorable for most of these individuals.8 Detection and stabilization of a vulnerable plaque by influencing the local disease process biologically would provide a sophisticated solution for asymptomatic plaque carriers at risk of stroke. Molecular Medicine© 2016 American Heart Association, Inc. Conclusions: An unstable carotid plaque at risk of stroke is characterized by low expression of miR-210. miR-210 contributes to stabilizing carotid plaques through inhibition of APC, ensuring smooth muscle cell survival. We present local delivery of miR-210 as a therapeutic approach for prevention of atherothrombotic vascular events.

SummaryLenalidomide activates the immune system, but the exact immunomodulatory mechanisms of lenalidomide in vivo are poorly defined. In an observational study we assessed the impact of lenalidomide on different populations of immune cells in multiple myeloma patients. Lenalidomide therapy was associated with increased amounts of a CD8 + T cell subset, phenotypically staged between classical central memory T cells (TCM) and effector memory T cells (TEM), consequently termed TCM/TEM. The moderate expression of perforin/granzyme and phenotypical profile of these cells identifies them as not yet terminally differentiated, which makes them promising candidates for the anti-tumour response. In addition, lenalidomide-treated patients showed higher abundance of CD14 + myeloid cells co-expressing CD15. This population was able to inhibit both CD4 + and CD8 + T cell proliferation in vitro and could thus be defined as a so far undescribed novel myeloid-derived suppressor cell (MDSC) subtype. We observed a striking correlation between levels of TCM/TEM, mature regulatory T cells (Tregs) and CD14 + CD15 + MDSCs. In summary, lenalidomide induces both activating and inhibitory components of the immune system, indicating the existence of potential counter-regulatory mechanisms. These findings provide new insights into the immunomodulatory action of lenalidomide.

miRNAs are potential regulators of carotid artery stenosis and concordant vulnerable atherosclerotic plaques. Hence, we analyzed miRNA expression in laser captured micro-dissected fibrous caps of either ruptured or stable plaques (n = 10 each), discovering that miR-21 was significantly downregulated in unstable lesions. To functionally evaluate miR-21 in plaque vulnerability, miR-21 and miR-21/apolipoprotein-E double-deficient mice (ApoemiR-21) were assessed. miR-21 mice lacked sufficient smooth muscle cell proliferation in response to carotid ligation injury. When exposing ApoemiR-21 mice to an inducible plaque rupture model, they presented with more atherothrombotic events (93%) compared with miR-21Apoe mice (57%). We discovered that smooth muscle cell fate in experimentally induced advanced lesions is steered via a REST-miR-21-REST feedback signaling pathway. Furthermore, ApoemiR-21 mice presented with more pronounced atherosclerotic lesions, greater foam cell formation, and substantially higher levels of arterial macrophage infiltration. Local delivery of a miR-21 mimic using ultrasound-targeted microbubbles into carotid plaques rescued the vulnerable plaque rupture phenotype. In the present study, we identify miR-21 as a key modulator of pathologic processes in advanced atherosclerosis. Targeted, lesion site-specific overexpression of miR-21 can stabilize vulnerable plaques.

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Acute ischemia of an extremity occurs in several stages, a lack of oxygen being the primary contributor of the event. Although underlying patho-mechanisms are similar, it is important to determine whether it is an acute or chronic event. Healthy tissue does not contain enlarged collaterals, which are formed in chronically malperfused tissue and can maintain a minimum supply despite occlusion. The underlying processes for enhanced collateral blood flow are sprouting vessels from pre-existing vessels (via angiogenesis) and a lumen extension of arterioles (via arteriogenesis). While disturbed flow patterns with associated local low shear stress upregulate angiogenesis promoting genes, elevated shear stress may trigger arteriogenesis due to increased blood volume. In case of an acute ischemia, especially during the reperfusion phase, fluid transfer occurs into the tissue while the vascular bed is simultaneously reduced and no longer reacts to vaso-relaxing factors such as nitric oxide. This process results in an exacerbative cycle, in which increased peripheral resistance leads to an additional lack of oxygen. This whole process is accompanied by an inundation of inflammatory cells, which amplify the inflammatory response by cytokine release. However, an extremity is an individual-specific composition of different tissues, so these processes may vary dramatically between patients. The image is more uniform when broken down to the single cell stage. Because each cell is dependent on energy produced from aerobic respiration, an event of acute hypoxia can be a life-threatening situation. Aerobic processes responsible for yielding adenosine triphosphate (ATP), such as the electron transport chain and oxidative phosphorylation in the mitochondria, suffer first, thus disrupting the integrity of cellular respiration. One consequence of this is irreparable damage of the cell membrane due to an imbalance of electrolytes. The eventual increase in net fluid influx associated with a decrease in intracellular pH is considered an end-stage event. Due to the lack of ATP, individual cell organelles can no longer sustain their activity, thus initiating the cascade pathways of apoptosis via the release of cytokines such as the BCL2 associated X protein (BAX). As ischemia may lead to direct necrosis, inflammatory processes are further aggravated. In the case of reperfusion, the flow of nascent oxygen will cause additional damage to the cell, further initiating apoptosis in additional surrounding cells. In particular, free oxygen radicals are formed, causing severe damage to cell membranes and desoxyribonucleic acid (DNA). However, the increased tissue stress caused by this process may be transient, as radical scavengers may attenuate the damage. Taking the above into final consideration, it is clearly elucidated that acute ischemia and subsequent reperfusion is a process that leads to acute tissue damage combined with end-organ loss of function, a condition that is difficult to counteract.