Atherosclerosis is a complex multifactorial disease that, despite advances in lifestyle management and drug therapy, remains to be the major cause of high morbidity and mortality rates from cardiovascular diseases (CVDs) in industrialized countries. Therefore, there is a great need in reliable diagnostic/prognostic biomarkers and effective treatment alternatives to reduce its burden. It was established that microRNAs (miRNAs/miRs), a class of non-coding single-stranded RNA molecules, can regulate the expression of genes at the post-transcriptional level and, accordingly, coordinate the cellular protein expression. Thus, they are involved not only in cell-specific physiological functions but also in the cellular and molecular mechanisms of human pathologies, including atherosclerosis. MiRNAs may be significant in the dysregulation that affects endothelial integrity, the function of vascular smooth muscle and inflammatory cells, and cellular cholesterol homeostasis that drives the initiation and growth of an atherosclerotic plaque. Besides, distinct expression patterns of several miRNAs are attributed to atherosclerotic and cardiovascular patients. In this article, the evidence indicating the multiple critical roles of miRNAs and their relevant molecular mechanisms related to atherosclerosis development and progression was reviewed. Moreover, the effects of miRNAs on atherosclerosis enabled to exploit them as novel diagnostic biomarkers and therapeutic targets that may lead to better management of atherosclerosis and CVDs.

Circulating monocytes are recruited to tissues, where they differentiate to macrophages and take part in the inflammation process or tissue remodeling. According to the traditional concept, macrophages are classified into pro-inflammatory (M1), non-activated (M0) or anti-inflammatory (M2) subsets that play distinct roles in the initiation and resolution of inflammation. This heterogeneity exists already at the monocyte level since monocytes can also belong to pro-or antiinflammatory phenotypes. Growth factors, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and M-CSF play a principal role in their activation: GM-CSF drives the differentiation of "pro-inflammatory" monocytes to M1 macrophages, while M-CSF regulates differentiation of the "anti-inflammatory" subset of monocytes to M0 macrophages that have M2-like phenotypic and functional properties. More recent experimental findings led to a substantial update of monocyte-macrophage nomenclature to include the nature of the polarizing signal. In response to pro-inflammatory stimuli, monocytes can be directly polarized into 3 subsets of macrophages with the pro-inflammatory M1-like phenotype; with macrophages induced by interferon-γ having the strongest pro-inflammatory properties. When exposed to various anti-inflammatory stimuli, monocytes can differentiate to at least 5 subsets of M2-like macrophages. Of those, a subset generated under exposure to IL-4 (IL-13) has the most typical M2-like characteristics. Both in humans and in mice, monocyte-to-macrophage differentiation involves global transcriptome changes that are tightly controlled by various transcriptional regulators and signaling mechanisms. In this review, we discuss monocyte-macrophage heterogeneity and signaling pathways regulating the differentiation at transcription level.

Atherosclerosis can be regarded as chronic inflammatory disease affecting the arterial wall. Despite the recent progress in studying the pathogenesis of atherosclerosis, some of the pathogenic mechanisms remain to be fully understood. Among these mechanisms is oxidative stress, which is closely linked to foam cells formation and other key events in atherosclerosis development. Two groups of enzymes are involved in the emergence of oxidative stress: Pro-oxidant (including NADPH oxidases, xanthine oxidases, and endothelial nitric oxide synthase) and antioxidant (such as superoxide dismutase, catalases, and thioredoxins). Pro-oxidant enzymes in normal conditions produce moderate concentrations of reactive oxidant species that play an important role in cell functioning and can be fully utilized by antioxidant enzymes. Under pathological conditions, activities of both pro-oxidant and antioxidant enzymes can be modified by numerous factors that can be relevant for developing novel therapies. Recent studies have explored potential therapeutic properties of antioxidant molecules that are capable to eliminate oxidative damage. However, the results of these studies remain controversial. Other perspective approach is to inhibit the activity of pro-oxidant enzymes and thus to slow down the progression of atherosclerosis. In this review we summarized the current knowledge on oxidative stress in atherosclerosis and potential antioxidant approaches. We discuss several important antioxidant molecules of plant origin that appear to be promising for treatment of atherosclerosis.

The risk of cardiovascular disease and atherosclerosis progression is significantly increased after menopause, probably due to the decrease of estrogen levels. The use of hormone replacement therapy (HRT) for prevention of cardiovascular disease in older postmenopausal failed to meet expectations. Phytoestrogens may induce some improvements in climacteric symptoms, but their effect on the progression of atherosclerosis remains unclear. The reduction of cholesterol accumulation at the cellular level should lead to inhibition of the atherosclerotic process in the arterial wall. The inhibition of intracellular lipid deposition with isoflavonoids was suggested as the effective way for the prevention of plaque formation in the arterial wall. The aim of this double-blind, placebo-controlled clinical study was to investigate the effect of an isoflavonoid-rich herbal preparation on atherosclerosis progression in postmenopausal women free of overt cardiovascular disease. One hundred fifty-seven healthy postmenopausal women (age 65 ± 6) were randomized to a 500 mg isoflavonoid-rich herbal preparation containing tannins from grape seeds, green tea leaves, hop cone powder, and garlic powder, or placebo. Conventional cardiovascular risk factors and intima-media thickness of common carotid arteries (cIMT) were evaluated at the baseline and after 12 months of treatment. After 12-months follow-up, total cholesterol decreased by 6.3% in isoflavonoid-rich herbal preparation recipients (p = 0.011) and by 5.2% in placebo recipients (p = 0.020); low density lipoprotein (LDL) cholesterol decreased by 7.6% in isoflavonoid-rich herbal preparation recipients (p = 0.040) and by 5.2% in placebo recipients (non-significant, NS); high density lipoprotein (HDL) cholesterol decreased by 3.4% in isoflavonoid-rich herbal preparation recipients (NS) and by 4.5% in placebo recipients (p = 0.038); triglycerides decreased by 6.0% in isoflavonoid-rich herbal preparation recipients (NS) and by 7.1% in placebo recipients (NS). The differences between lipid changes in the isoflavonoid-rich herbal preparation and placebo recipients did not reach statistical significance (p > 0.05). Nevertheless, the mean cIMT progression was significantly lower in isoflavonoid-rich herbal preparation recipients as compared to the placebo group (6 μm, or <1%, versus 100 μm, or 13%; p < 0.001 for the difference). The growth of existing atherosclerotic plaques in isoflavonoid-rich herbal preparation recipients was inhibited by 1.5-fold (27% versus 41% in the placebo group). The obtained results demonstrate that the use of isoflavonoid-rich herbal preparation in postmenopausal women may suppress the formation of new atherosclerotic lesions and reduce the progression of existing ones, thus promising new drug for anti-atherosclerotic therapy. Nevertheless, further studies are required to confirm these findings.

The current view on atherosclerosis positions it as a multifactorial disorder that results from the interplay between lipid metabolism disturbances and inflammatory processes. Oxidative stress is proven to be one of the initiating factors in atherosclerosis development, being implicated both in the inflammatory response and in atherogenic modifications of lipoproteins that facilitate lipid accumulation in the arterial wall. The hallmark of oxidative stress is the elevated level of reactive oxygen species (ROS). Correspondingly, the activity of major ROS-generating enzymes, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, and cyclooxygenases, is an important element in atherosclerosis development. In particular, the role of NADPH oxidases in atherosclerosis development has become a subject of intensive research. Aberrant activity of NADPH oxidases was shown to be associated with cardiovascular disease in humans. With regard to atherosclerosis, several important pathological components of the disease development, including endothelial dysfunction, inflammation, and vascular remodeling, involve aberrations in NADPH oxidases functioning. In humans, NADPH oxidases are represented by four isoforms expressed in vascular tissues, where they serve as the main source of ROS during atherogenesis. Moreover, recent studies have demonstrated their impact on vascular remodeling processes. Interestingly, one of the NADPH oxidase isoforms, NOX4, was shown to have an atheroprotective effect. Despite the growing evidence of the crucial involvement of NADPH oxidases in atherosclerosis pathogenesis, the available data still remains controversial. In this narrative review, we summarize the current knowledge of the role of NADPH oxidases in atherosclerosis and outline the future directions of research.