Background: Chronic activation of the innate immune system drives inflammation and contributes directly to atherosclerosis. Previously, we showed that macrophages in the atherogenic plaque undergo RIPK3-MLKL-dependent programmed necroptosis in response to sterile ligands such as oxidized LDL and damage-associated patterns (DAMPs) and necroptosis is active in advanced atherosclerotic plaques. Upstream of the RIPK3-MLKL necroptotic machinery lies RIPK1, which acts as a master switch that controls whether the cell undergoes NFκB-dependent inflammation, caspase-dependent apoptosis or necroptosis in response to extracellular stimuli. We therefore set out to investigate the role of RIPK1 in the development of atherosclerosis, which is largely driven by NFκB-dependent inflammation at early stages. We hypothesize that, unlike RIPK3 and MLKL, RIPK1 primarily drives NFκB-dependent inflammation in early atherogenic lesions and knocking down RIPK1 will reduce inflammatory cell activation and protect against the progression of atherosclerosis. Methods: We examined expression of RIPK1 protein and mRNA in both human and mouse atherosclerotic lesions, and using loss-of-function approaches in vitro in macrophages and endothelial cells to measure inflammatory responses. We administered weekly injections of RIPK1 anti-sense oligonucleotides (ASO) to Apoe -/- mice fed a cholesterol-rich (Western) diet for 8 weeks. Results: We find RIPK1 expression is abundant in early-stage atherosclerotic lesions in both humans and mice. Treatment with RIPK1 ASOs led to a reduction in aortic sinus and en face lesion areas (47.2% or 58.8% decrease relative to control, p<0.01) and plasma inflammatory cytokines (IL-1α, IL-17A, p<0.05) compared to controls. RIPK1 knockdown in macrophages decreased inflammatory genes (NFκB, TNFα, IL-1α) and in vivo LPS- and atherogenic diet-induced NF-κB activation. In endothelial cells, knockdown of RIPK1 prevented NF-κB translocation to the nucleus in response to TNFα, where accordingly there was a reduction in gene expression of IL1B, E-selectin and monocyte attachment. Conclusions: We have identified RIPK1 as a central driver of inflammation in atherosclerosis by its ability to activate the NF-κB pathway and promote inflammatory cytokine release. Given the high levels of RIPK1 expression in human atherosclerotic lesions, our study suggests RIPK1 as a future therapeutic target to reduce residual inflammation in patients at high risk of coronary artery disease.

Despite the promising value of miRnAs in the diagnostic and prognostic of cardiovascular disease (CVD), recent meta-analyses did not support their potential. Methodological variances in studies may interfere with miRNA profile and affect their results. This study determines if the blood starting material is a source of variance in miRNA profile by performing a paired comparison in plasma and serum of the expression of primary miRNAs associated with CVD. Circulating miRNA yield was similar in both plasma and serum, although a significant increase was observed in patients with Non-ST-elevation myocardial infarction (NSTEMI) compared to control volunteers. When normalized by the expression of miR-484, different patterns of miRNA expression between serum and plasma. Although NSTEMI modified the expression of miR-1 and miR-208 in both serum and plasma, plasma displayed a higher variance than serum (Levene's test p < 0.01). For miR-133a and miR-26a, differences were only detected in serum (p = 0.0240), and conversely, miR-499a showed differences only in plasma of NSTEMI (p = 0.001). Interestingly, miR-21 showed an opposite pattern of expression, being increased in serum (2 −ΔΔct : 5.7, p = 0.0221) and decreased in plasma (2 −ΔΔct : 0.5, p = 0.0107). Plasma and serum exhibit different patterns of circulating miRNA expression in NSTEMI and suggest that results from studies with different starting material could not be comparable. MicroRNAs (miRNA) are highly conserved small noncoding RNAs that regulate post-transcriptional gene expression 1. Through this mechanism, miRNAs regulate silencing of gene expression and can modify cell and tissue phenotype. Even though the existence of miRNAs and their mechanisms of action are not recent discoveries, the clinical implications of these micro molecules are relatively new and still a focus of debate. miRNAs can act intracellularly 1 or be actively secreted by cells and contribute to intercellular or cell-tissue communication 1. miR-NAs are remarkably stable in human biofluids 2 , including plasma and serum, due to their packaging into membranous vesicles including exosomes, microvesicles, and apoptotic bodies, and to the association to RNA-binding proteins, such as the Argonaute family of lipoprotein complexes like high-density lipoprotein 3. As a result, circulating miRNAs have emerged as powerful diagnostic or prognostic biomarkers in different pathophysiological conditions, including cardiovascular disease (CVD) 4. A large number of independent clinical studies and basic science in animal models have described distinct patterns of miRNA expression in CVD and associated risk factors, reinforcing the potential use of miRNA as

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Women show a lower incidence of cardiovascular diseases than age‐matched men, but this benefit disappears after menopause. Oestrogen‐mediated vascular actions are mainly attributed to oestradiol and exerted by oestrogen receptors (ERα, ERβ and G protein‐coupled oestrogen receptor), through rapid and/or genomic mechanisms, but these effects depend on ageing and inflammation. A cardiovascular approach in women's health has arisen due to controversy regarding oestrogen's beneficial impact as reported in experimental and observational studies and large randomized trials. These can be explained, in part, by two mutually non‐exclusive hypotheses. On the one hand, the timing hypothesis, which states that oestrogen‐mediated benefits occur before the detrimental effects of ageing are established in the vasculature; on the other hand, ageing and/or hormonal‐associated changes in ER expression that could lead to a deleterious imbalance in favour of ERβ over ERα, generally associated with higher inflammation and endothelial dysfunction. In experimental studies, oestradiol acting on ERα promotes the release of vasoactive compounds such as nitric oxide (NO) and prostacyclin, and shifts the angiotensin axis towards angiotensin 1–7 production. Mechanisms underlying oestradiol vascular function also include anti‐inflammatory and epigenetic modifications. 17β‐Oestradiol changes the transcriptomic profile of endothelial cells, and the involvement of miRNA in the regulatory pathways of vascular function reinforces assumptions regarding the vascular actions of oestrogen. Thus, the present Symposium Review aims to postulate the role of ERα in oestrogen modulation of endothelium‐derived mediators and vascular physiology, as well as its relationship with miRNA and inflammation, and elucidate how physiological changes in postmenopausal women counteract the observed effects.

Background/Aims: Estrogen signalling plays an important role in vascular biology as it modulates vasoactive and metabolic pathways in endothelial cells. Growing evidence has also established microRNA (miRNA) as key regulators of endothelial function. Nonetheless, the role of estrogen regulation on miRNA profile in endothelial cells is poorly understood. In this study, we aimed to determine how estrogen modulates miRNA profile in human endothelial cells and to explore the role of the different estrogen receptors (ERα, ERβ and GPER) in the regulation of miRNA expression by estrogen. Methods: We used miRNA microarrays to determine global miRNA expression in human umbilical vein endothelial cells (HUVEC) exposed to a physiological concentration of estradiol (E2; 1 nmol/L) for 24 hours. miRNAgene interactions were computationally predicted using Ingenuity Pathway Analysis and changes in miRNA levels were validated by qRT-PCR. Role of ER in the E2-induced miRNA was additionally confirmed by using specific ER agonists and antagonists. Results: miRNA array revealed that expression of 114 miRNA were significantly modified after E2 exposition. Further biological pathway analysis revealed cell death and survival, lipid metabolism, reproductive system function, as the top functions regulated by E2. We validated changes in the most significantly increased (miR-30b-5p, miR-487a-5p, miR-4710, miR-501-3p) and decreased (miR-378h and miR-1244) miRNA and the role of ER in these E2-induced miRNA was determined. Results showed that both classical, ERα and ERβ, and membrane-bound ER, GPER, differentially regulated specific miRNA. In silico analysis of validated miRNA promoters identified specific ER binding sites. Conclusion: Our findings identify differentially expressed miRNA pathways linked to E2 in human endothelial cells through ER, and provide new insights by which estrogen can modulate endothelial function.

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The beneficial effects of estrogen on the cardiovascular system have been reported extensively. In fact, the incidence of cardiovascular diseases in women is lower than in age-matched men during their fertile stage of life, a benefit that disappears after menopause. These sex-related differences point to sexual hormones, mainly estrogen, as possible cardiovascular protective factors. The regulation of vascular function by estrogen is mainly related to the maintenance of normal endothelial function and is mediated by both direct and indirect gene transcription through the activity of specific estrogen receptors. Some of these mechanisms are known, but many remain to be elucidated. In recent years, microRNAs have been established as non-coding RNAs that regulate the expression of a high percentage of protein-coding genes in mammals and are related to the correct function of human physiology. Moreover, within the cardiovascular system, miRNAs have been related to physiological and pathological conditions. In this review, we address what is known about the role of estrogen-regulated miRNAs and their emerging involvement in vascular biology.