Sialic acid as the potential link between lipid metabolism and inflammation in the pathogenesis of atherosclerosis.

In the modern world, cardiovascular diseases have a special place among the most common causes of death. Naturally, this widespread problem cannot escape the attention of scientists and researchers. One of the main conditions preceding the development of fatal cardiovascular diseases is atherosclerosis. Despite extensive research into its pathogenesis and possible prevention and treatment strategies, many gaps remain in our understanding of this disease. For example, the concept of multiple low-density lipoprotein modifications was recently stated, in which desialylation is of special importance. Apart from this, sialic acids are known to be important contributors to processes such as endothelial dysfunction and inflammation, which in turn are major components of atherogenesis. In this review, we have collected information on sialic acid metabolism, analyzed various aspects of its implication in atherosclerosis at different stages, and provided an overview of the role of particular groups of enzymes responsible for sialic acid metabolism in the context of atherosclerosis.

Sialic acid as the potential link between lipid metabolism and inflammation in the pathogenesis of atherosclerosis

In the modern world, cardiovascular diseases have a special place among the most common causes of death. Naturally, this widespread problem cannot escape the attention of scientists and researchers. One of the main conditions preceding the development of fatal cardiovascular diseases is atherosclerosis. Despite extensive research into its pathogenesis and possible prevention and treatment strategies, many gaps remain in our understanding of this disease. For example, the concept of multiple low-density lipoprotein modifications was recently stated, in which desialylation is of special importance. Apart from this, sialic acids are known to be important contributors to processes such as endothelial dysfunction and inflammation, which in turn are major components of atherogenesis. In this review, we have collected information on sialic acid metabolism, analyzed various aspects of its implication in atherosclerosis at different stages, and provided an overview of the role of particular groups of enzymes responsible for sialic acid metabolism in the context of atherosclerosis.

Animal models of human atherosclerosis: current progress.

Atherosclerosis retains the leading position among the causes of global morbidity and mortality worldwide, especially in the industrialized countries. Despite the continuing efforts to investigate disease pathogenesis and find the potential points of effective therapeutic intervention, our understanding of atherosclerosis mechanisms remains limited. This is partly due to the multifactorial nature of the disease pathogenesis, when several factors so different as altered lipid metabolism, increased oxidative stress, and chronic inflammation act together leading to the formation and progression of atherosclerotic plaques. Adequate animal models are currently indispensable for studying these processes and searching for novel therapies. Animal models based on rodents, such as mice and rats, and rabbits represent important tools for studying atherosclerosis. Currently, genetically modified animals allow for previously unknown possibilities in modelling the disease and its most relevant aspects. In this review, we describe the recent progress made in creating such models and discuss the most important findings obtained with them to date.

Animal models of human atherosclerosis: current progress

Atherosclerosis retains the leading position among the causes of global morbidity and mortality worldwide, especially in the industrialized countries. Despite the continuing efforts to investigate disease pathogenesis and find the potential points of effective therapeutic intervention, our understanding of atherosclerosis mechanisms remains limited. This is partly due to the multifactorial nature of the disease pathogenesis, when several factors so different as altered lipid metabolism, increased oxidative stress, and chronic inflammation act together leading to the formation and progression of atherosclerotic plaques. Adequate animal models are currently indispensable for studying these processes and searching for novel therapies. Animal models based on rodents, such as mice and rats, and rabbits represent important tools for studying atherosclerosis. Currently, genetically modified animals allow for previously unknown possibilities in modelling the disease and its most relevant aspects. In this review, we describe the recent progress made in creating such models and discuss the most important findings obtained with them to date.

Correction to: Rehmanniae Radix Preparata suppresses bone loss and increases bone strength through interfering with canonical Wnt/ß-catenin signaling pathway in OVX rats.

There was a mistake in the part of OVX rats model and RRP intervention in the original publication.

An update on the tools for creating transgenic animal models of human diseases - focus on atherosclerosis.

Animal models of diseases are invaluable tools of modern medicine. More than forty years have passed since the first successful experiments and the spectrum of available models, as well as the list of methods for creating them, have expanded dramatically. The major step forward in creating specific disease models was the development of gene editing techniques, which allowed for targeted modification of the animal's genome. In this review, we discuss the available tools for creating transgenic animal models, such as transgenesis methods, recombinases, and nucleases, including zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and CRISPR/Cas9 systems. We then focus specifically on the models of atherosclerosis, especially mouse models that greatly contributed to improving our understanding of the disease pathogenesis and we outline their characteristics and limitations.

Rehmanniae Radix Preparata suppresses bone loss and increases bone strength through interfering with canonical Wnt/ß-catenin signaling pathway in OVX rats.

Rehmanniae Radix Preparata (RRP) improves bone quality in OVX rats through the regulation of bone homeostasis via increasing osteoblastogenesis and decreasing osteoclastogenesis, suggesting it has a potential for the development of new anti-osteoporotic drugs. INTRODUCTION: Determine the anti-osteoporotic effect of RRP in ovariectomized (OVX) rats and identify the signaling pathway involved in this process. METHODS: OVX rats were treated with RRP aqueous extract for 14 weeks. The serum levels of tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear factor kappa-Β ligand (RANKL), alkaline phosphatase (ALP), and osteoprotegerin (OPG) were determined by ELISA. Bone histopathological alterations were evaluated by H&E, Alizarin red S, and Safranin O staining. Bone mineral density (BMD) and bone microstructure in rat femurs and lumbar bones were determined by dual-energy X-ray absorptiometry and micro-computed tomography. Femoral bone strength was detected by a three-point bending assay. The expression of Phospho-glycogen synthase kinase 3 beta (p-GSK-3ß), GSK-3ß, Dickkopf-related protein 1 (DKK1), cathepsin K, OPG, RANKL, IGF-1, Runx2, ß-catenin, and p-ß-catenin was determined by western blot and/or immunohistochemical staining. RESULTS: Treatment of OVX rats with RRP aqueous extract rebuilt bone homeostasis demonstrated by increasing the levels of OPG as well as decreasing the levels of TRAP, RANKL, and ALP in serum. Furthermore, RRP treatment preserved BMD and mechanical strength by increasing cortical bone thickness and epiphyseal thickness as well as improving trabecular distribution in the femurs of OVX rats. In addition, RRP downregulated the expression of DKK1, sclerostin, RANKL, cathepsin K, and the ratio of p-ß-catenin to ß-catenin, along with upregulating the expression of IGF-1, ß-catenin, and Runx2 and the ratio of p-GSK-3ß to GSK-3ß in the tibias and femurs of OVX rats. Echinacoside, jionoside A1/A2, acetoside, isoacetoside, jionoside B1, and jionoside B2 were identified in the RRP aqueous extract. CONCLUSION: RRP attenuates bone loss and improves bone quality in OVX rats partly through its regulation of the canonical Wnt/ß-catenin signaling pathway, suggesting that RRP has the potential to provide a new source of anti-osteoporotic drugs.

An update on the tools for creating transgenic animal models of human diseases - focus on atherosclerosis

Animal models of diseases are invaluable tools of modern medicine. More than forty years have passed since the first successful experiments and the spectrum of available models, as well as the list of methods for creating them, have expanded dramatically. The major step forward in creating specific disease models was the development of gene editing techniques, which allowed for targeted modification of the animal's genome. In this review, we discuss the available tools for creating transgenic animal models, such as transgenesis methods, recombinases, and nucleases, including zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and CRISPR/Cas9 systems. We then focus specifically on the models of atherosclerosis, especially mouse models that greatly contributed to improving our understanding of the disease pathogenesis and we outline their characteristics and limitations.

Diagnostics and Therapy of Human Diseases - Focus on Sialidases.

Sialic acid residues that make part of the cell surface repertoire of carbohydrate residues are implicated in various physiological processes and human pathologies. Sialidases, or neuraminidases, are the enzymes that are able to cleave and release the sialic acid residues, while trans-sialidases can transfer the residues from donor to acceptor molecules. They are important for processing the surface glycolipids and glycoproteins. Therapeutic potential of pharmacological sialidases inhibition is currently actively studied. Knowledge and expertise gained from genetic defects leading to human sialidase deficiency can be used for designing such drugs. In this review, we discuss the current progress in studying sialidases and their inhibitors and the relevance of these studies to developing novel therapeutic approaches. In vitro studies suggest that some sialidase inhibitors might be useful therapeutics for treating sialidosis, cancer, infections, immune diseases, atherosclerosis and other pathologies. Consequently, there is a field for further research and development. A thorough investigation of human sialidases is therefore crucial to human health.

[Study of mitochondrial dysfunction using cytoplasmic hybrid].

Aim. This review article describes literature sources devoted to the investigation of mitochondrial dysfunction using cytoplasmic hybrids (cybrids). The presented studies were carried out on cultures of cybrid cell lines HL60, MOL T-4, A549, 143B, HeLa, Arpe-19, HEK-293, SH-SY5Y and NT2. According to the analysis of scientific world literature, some of the most promising models for studying mitochondrial dysfunction are cell cultures without mitochondria (rho0) and cytoplasmic hybrids containing one or several mutations of mitochondrial genome. In the review scientific researches on studying biochemical and molecular cellular pathological processes in cybrid cells in various human diseases such as Alzheimer's disease and mild cognitive impairment, MERRF and MELAS syndromes, Leber's optic atrophy and Parkinson's disease were considered. Material dedicated to cybrids as potential models for the study of treatment possibilities was presented separately. Conclusion. The analyzed in the review rho0-cell cultures and cybrid lines containing mtDNA mutations may be models for the study of mitochondrial genome dysfunctions, biochemical and molecular cellular pathological processes. It is worth noting that in various cell cultures, similar tendencies are observed in functional activity changes of rho0-cell and cybrids compared with native cell lines. For example, such tendencies as reduction of oxygen consumption level, morphological changes of mitochondrial structure, resistance to apoptosis, reduction of ATP consumption level, increase in glucose consumption, activity deterioration of some respiratory chain complexes.

Influence of autophagy on the genesis and development of atherosclerosis and its risk factors. / Vliianie autofagii na vozniknovenie i razvitie ateroskleroza i ego faktorov riska.

Autophagy is a highly conservative process of degeneration during which intracellular components including soluble macromolecules (e. g., nucleic acids, proteins, carbohydrates and lipids) and dysfunctional organelles (e. g., mitochondria, peroxisomes, and the endoplasmatic reticulum) are degraded by a lysosome. Autophagy serves as a dynamic system of recycling proving cells with energy and building components. Because of it in cells of an organism new proteins and membranes can form contributing to survival of the individual under starvation conditions. Autophagy plays an important role in the genesis and development of multifactorial pathogenesis including atherosclerosis and its risk factors. The present article examines both a pathogenic and protective role of autophagy in such pathological processes. The article can be useful to molecular biologists and biochemists, as well as to professionals involved in the problems of atherosclerosis and cardiovascular diseases.

[Peculiarities of secretion of cytokines and chemokines by human blood monocytes in atherosclerosis]. / Osobennosti sekretsii tsitokinov i khemokinov monotsitami krovi cheloveka pri ateroskleroze.

The study included apparently healthy people, conventionally healthy people predisposed to atherosclerosis, and as well as people with preclinical atherosclerosis (50 subjects in each group). Monocytes were isolated from whole blood and transferred to culture followed by studying pro- and anti-inflammatory activation of monocytes in response to stimulation by interferon-gamma and interleukin-4, respectively. As a marker of pro-inflammatory activation was the level of secretion of tumour necrosis factor-α (TNF-α) in the culture medium measured by means of immunoenzymatic assay. Chemokine CCL18 served as a marker of anti-inflammatory activation. We also examined secretion of a series of other chemokines and cytokines: MCO-1, IL-6, IL-1ß, IL-8, GM-CFS, and others. Pronounced individual differences of cytokines and chemokines secretion were revealed in all groups. We carried out assessment the degree of altering secretion of cytokines and chemokines by stimulated monocytes compared with unstimulated culture. This approach may serve as an effective tool for assessment an individual reaction of congenital immunity.

Phytoestrogen-Rich Natural Preparation for Treatment of Climacteric Syndrome and Atherosclerosis Prevention in Perimenopausal Women.

The present study evaluated the risks and benefits of phytoestrogen treatment in healthy perimenopausal women in relation to the dynamics of climacteric syndrome and progression of atherosclerosis. Study participants were treated with placebo or phytoestrogen-rich natural preparation Karinat based on grape (Vitis vinifera) seeds, green tea (Camellia sinensis) leaves, hop (Hunulus lupulus) cone powder and garlic (Allium sativum) powder. The dynamics of climacteric syndrome was evaluated by Kupperman Index and Utian Quality of Life Scale. Atherosclerosis progression was evaluated by measuring carotid intima-media thickness. Significant changes of climacteric syndrome's severity in both Karinat and placebo groups (p = 0.005 and p = 0.001) were obtained after 24 months of follow-up. Detailed analysis of Kupperman Index suggested that Karinat possessed a significant effect on nervousness (p = 0.010), weakness (p = 0.020) and formication (p = 0.010). A significant improvement of medical (p = 0.070) and emotional (p = 0.060) components of Kupperman Index and Utian Quality of Life Scale was also observed in Karinat group. However, difference in carotid intima-media thickness between the two groups was not statistically significant at follow-up. A slight positive effect of phytoestrogens on climacteric syndrome manifestations was demonstrated in this study. Karinat can be used for alleviation of climacteric syndrome and cardiovascular disease prevention in perimenopausal women. Copyright © 2017 John Wiley & Sons, Ltd.

Multiple-modified Low-Density Lipoprotein as Atherogenic Factor of Patients' Blood: Development of Therapeutic Approaches to Reduce Blood Atherogenicity.

Generally, atherosclerosis first occurs by the way of accumulation of intracellular and extracellular lipids in the arterial intima. Foam cells, overloaded by lipids, are the essential harbinger of the coronary artery disease. It should be noted that lipids that are usually composed of bulk of the intracellular lipids found in human arterial cells originate from low-density lipoprotein (LDL) circulating in human blood. Nonetheless, many efforts to force cells to accumulate cholesteryl esters under the influence of native LDL have been unsuccessful. Whilst LDL modified in vitro (exposed to malondialdehyde, oxidized with ions of transition metals, acetylated, etc.) promoted accumulation of lipids in cells, all the attempts made for the sake of hunting down such LDLs in the bloodstream still do not provide confident conclusions. Therefore, a controversy arose: firstly, lipids from the cells of vascular wall have proved to be descending from LDL; secondly, foam cells do not form under the influence of native LDL in vitro (i.e. no visible intracellular lipid deposition observed); thirdly, chemically manipulated LDL seems to possess atherogenic properties. Acetylated LDL was not found in the bloodstream; similarly, the existence of oxidized LDL in the circulation remains controversial. Such a conundrum sparked a thorough investigation, leading to some interesting results. Modified desialylated LDL in human blood stream has been identified, which was able to promote lipid deposition in cultured cells. Such an LDL has been isolated, displaying atherogenic properties. The atherogenic LDL seems to deviate in multiple features from its non-atherogenic counterparts: carbohydrate, protein, and lipid moieties which were mangled. Such multiple LDL transformations take place in human blood stream and seem to denote a succession of events forcing the particle to become atherogenic: desialylation, lipid loss, shrinkage, rising of surface electronegative charge, etc. On top of the fat deposition in cells, multiple modifications of LDL as well as some other deleterious effects, like cell proliferation and fibrosis, seem to be part of the chain of events finally unfolding into a full-scale atherosclerotic lesion.

Effects of shear stress on endothelial cells: go with the flow.

Haemodynamic forces influence the functional properties of vascular endothelium. Endothelial cells (ECs) have a variety of receptors, which sense flow and transmit mechanical signals through mechanosensitive signalling pathways to recipient molecules that lead to phenotypic and functional changes. Arterial architecture varies greatly exhibiting bifurcations, branch points and curved regions, which are exposed to various flow patterns. Clinical studies showed that atherosclerotic plaques develop preferentially at arterial branches and curvatures, that is in the regions exposed to disturbed flow and shear stress. In the atheroprone regions, the endothelium has a proinflammatory phenotype associated with low nitric oxide production, reduced barrier function and increased proadhesive, procoagulant and proproliferative properties. Atheroresistant regions are exposed to laminar flow and high shear stress that induce prosurvival antioxidant signals and maintain the quiescent phenotype in ECs. Indeed, various flow patterns contribute to phenotypic and functional heterogeneity of arterial endothelium whose response to proatherogenic stimuli is differentiated. This may explain the preferential development of endothelial dysfunction in arterial sites with disturbed flow.

[Dietary phospholipids: lipid metabolism and risk factors for cardiovascular diseases].

Eggs are a major source of phospholipids (PL) in the Western diet. Dietary PL have emerged as a potential source of bioactive lipids that may have widespread effects on pathways related to inflammation, cholesterol metabolism, and high-density lipoprotein (HDL) function. Based on pre-clinical studies, egg phosphatidylcholine (PC) and sphingomyelin appeared to regulate cholesterol absorption and inflammation. In clinical studies, egg PL intake is associated with beneficial changes in biomarkers related to HDL reverse cholesterol transport. Recently, egg PC was shown to be a substrate for the generation of trimethylamine N-oxide (TMAO), a gut microbe-dependent metabolite associated with increased cardiovascular disease (CVD) risk. More researches are warranted to examine potential serum TMAO responses to chronic egg ingestion and in different populations, such as diabetics. In this review, the recent basic science, clinical, and epidemiological findings examining egg PL intake and risk of CVD are summarized.

[DESIALATED LOW DENSITY LIPOPROTEINS IN HUMAN BLOOD].

The present article is a review of literature on circulating low-density lipoproteins (LDLP) which can induce accumulation of lipids (mainly, cholesterol), in a SMA(+) cell culture of normal human aortic intima. An attempt was undertaken to resolve the paradox of the absence of both native LDLP influence on intracellular lipid accumulation and modifications of in vitro obtained LDLP in the blood-vascular system. It was showed that atherogenic LDLPs are characterized by a number of changes in carbon, protein and lipid components which can be regarded as multiple modifications of LDLP taking place in human blood plasma. Multiply modified circulating LDLP possess of capacity to interact with various cell membrane receptors differing from B and E receptor, and with proteoglycans. Marked absorption of desiliated LDLPs by the cells simultaneous with a decrease in the degradation of apolipoproteins and cholesterol esters as well as induction of peresterification of free cholesterol leads to intracellular accumulation of esterified cholesterol. Formation of large LDLP-containing complexes especially circulating low-density lipoproteins can stimulate accumulation of lipids by smooth muscle cells of intima. Desiliated LDLPs stimulated cell proliferation and connective tissue matrix synthesis despite cholesterol ester accumulation. In conclusion, the authors of this article found and characterized natural multiply modified LDLPs that can be responsible for the symptoms of atherosclerosis at the cellular level.

[Modified circulating low-density lipoproteins: pathogenetic significance in angiology]. / Modifitsirovannye tsirkuliruyushchie lipoproteidy nizkoi plotnosti: patogeneticheskaya znachimost' v angiologii.

Low-density lipoproteins (LDLs) having various modifications are known to be atherogenic, i. e., possessing ability of inducing atherosclerosis. Circulating modified LDLs (cmLDLs) were found in blood of patients diagnosed with atherosclerosis confirmed angiographically. They appear to contain 2-3-fold less sialic acid as compared to LDLs in blood of apparently healthy people; cmLDLs differ by their physical properties: having higher density, smaller diameter, and greater electronegativity; by chemical properties: the amount of neutral sugars (N-acetyl-galactosamine, N-acetyl-glucosamine, galactose and glucose) in cmLSLs of patients with atherosclerosis is 1,5-2 times lower than in native lipoproteins, the levels of free and etherified cholesterol and triglycerides, monoglycerides and free fatty acids are higher, cmLDLs are oxidized and contain altered apolipoprotein B. It is also known that cmLDLs enhance proliferation of subendothelial smooth-muscle cells of the vascular intima, activating synthesis of protein by cells and components of the connective-tissue matrix, determining early clinical manifestations of atherosclerosis. The presented review summarizes the results of many-year studies of cmLDLs, carried out at the Scientific Research Institute for Atherosclerosis and the Laboratory of Angiopathology of the Scientific Research Institute of General Pathology and Pathophysiology both headed by A.N. Orekhov, and dedicated to various aspects of the effect of modified LDLs on the inner vascular wall.

[Atherogenic modification of low-density lipoproteins]. / Aterogennye modifikatsii lipoproteinov nizkoi plotnosti.

One of the first manifestations of atherosclerosis is accumulation of extra- and intracellular cholesterol esters in the arterial intima. Formation of foam cells is considered as a trigger in the pathogenesis of atherosclerosis. Low density lipoprotein (LDL) circulating in human blood is the source of lipids accumulated in the arterial walls. This review considered features and role in atherogenesis different modified forms of LDL: oxidized, small dense, electronegative and especially desialylated LDL. Desialylated LDL of human blood plasma is capable to induce lipid accumulation in cultured cells and it is atherogenic. LDL possesses numerous alterations of protein, carbohydrate and lipid moieties and therefore can be termed multiple-modified LDL. Multiple modification of LDL occurs in human blood plasma and represents a cascade of successive changes in the lipoprotein particle: desialylation, loss of lipids, reduction in the particle size, increase of surface electronegative charge, etc. In addition to intracellular lipid accumulation, stimulatory effects of naturally occurring multiple-modified LDL on other processes involved in the development of atherosclerotic lesions, namely cell proliferation and fibrosis, were shown.

Lipid composition of circulating multiple-modified low density lipoprotein.

Atherogenic modified low- density lipoprotein (LDL) induces pronounced accumulation of cholesterol and lipids in the arterial wall, while native LDL seems to lack such capability. Therefore, modified LDL appears to be a major causative agent in the pathogenesis of atherosclerosis. Possible modifications of LDL particles include changes in size and density, desialylation, oxidation and acquisition of negative charge. Total LDL isolated from pooled plasma of patients with coronary atherosclerosis, as well as from healthy subjects contains two distinct subfractions: normally sialylated LDL and desialylated LDL, which can be isolated by binding to a lectin affinity column. We called the desialylated LDL subfraction circulating modified LDL (cmLDL). In this study, we focused on lipid composition of LDL particles, analysing the total LDL preparation and two LDL subfractions: cmLDL and native LDL. The composition of LDL was studied using thin-layer chromatography. We found that cmLDL subfraction had decreased levels of free and esterified cholesterol, triglycerides, phospholipids (except for lysophosphatidylcholine) and sphingomyelin in comparison to native LDL. On the other hand, levels of mono-, and diglycerides, lysophosphatidylcholine and free fatty acids were higher in cmLDL than in native LDL. Our study demonstrated that lipid composition of cmLDL from atherosclerotic patients was altered in comparison to healthy subjects. In particular, phospholipid content was decreased, and free fatty acids levels were increased in cmLDL. This strengthens the hypothesis of multiple modification of LDL particles in the bloodstream and underscores the clinical importance of desialylated LDL as a possible marker of atherosclerosis progression.