Mouse Model of Low-density Lipoprotein Desialylation In Vivo.

BACKGROUND: Atherosclerosis is a chronic disease characterized by the increased infiltration and retention of LDL particles in arterial walls. There are several mechanisms underlying atherogenesis, with the pro-atherogenic modifications of LDL playing a significant role. One such modification of native LDL is desialylation, which is characterized by the removal of terminal sialic acid from ApoB-100 glycans that induces critical changes in the overall functionality of the LDL particle. AIMS: The aim of this study was to model the desialylation of native LDL in mice, resembling a phenomenon previously observed in atherosclerotic patients. OBJECTIVE: LDL desialylation was induced in C57BL/6J mice via the injection of exogenous neuraminidase. The degree of LDL desialylation and its duration were assessed. The impact of LDL desialylation on blood lipid levels was evaluated. Furthermore, the morphological alterations in the aorta during LDL desialylation in the bloodstream were examined. METHOD: The control group of C57BL/6J mice received saline injections, while the experimental group underwent a single injection of IgG-conjugated Vibrio cholerae neuraminidase. The LDL sialic acid levels were assessed 1-7 days post-injection using the Warren method and normalized to total protein content measured via the Lowry method. A similar protocol was followed for the subchronic administration of the IgG-neuraminidase conjugate over a 6-week period. The blood lipid profiles were analyzed using commercial kits. The atherosclerotic plaque burden in the mouse aorta was quantified using Oil Red O and hematoxylin-eosin staining. RESULT: A single administration of 20 mU IgG-neuraminidase conjugate resulted in decreased LDL sialic acid levels for 5 days, gradually recovering by days 6-7. Subchronic administration maintained reduced LDL sialic acid levels for up to 2 months. Notably, sustained LDL desialylation was associated with elevated LDL cholesterol levels. CONCLUSION: A sustained desialylation of LDL in C57BL/6J mice was achieved through subchronic administration of IgG-conjugated neuraminidase. This study provides an approach for sustained LDL desialylation in mice. Further studies using apolipoprotein E knockout mice and LDL desialylation will reveal the role of this process in the occurrence and development of atherosclerosis.

The Role of Bacterial Extracellular Membrane Nanovesicles in Atherosclerosis: Unraveling a Potential Trigger.

PURPOSE OF REVIEW: In this review, we explore the intriguing and evolving connections between bacterial extracellular membrane nanovesicles (BEMNs) and atherosclerosis development, highlighting the evidence on molecular mechanisms by which BEMNs can promote the athero-inflammatory process that is central to the progression of atherosclerosis. RECENT FINDINGS: Atherosclerosis is a chronic inflammatory disease primarily driven by metabolic and lifestyle factors; however, some studies have suggested that bacterial infections may contribute to the development of both atherogenesis and inflammation in atherosclerotic lesions. In particular, the participation of BEMNs in atherosclerosis pathogenesis has attracted special attention. We provide some general insights into how the immune system responds to potential threats such as BEMNs during the development of atherosclerosis. A comprehensive understanding of contribution of BEMNs to atherosclerosis pathogenesis may lead to the development of targeted interventions for the prevention and treatment of the disease.

Exosomes in Atherosclerosis: Role in the Pathogenesis and Targets for Therapy.

Atherosclerotic cardiovascular disease (ASCVD) is an advanced chronic inflammatory disease and the leading cause of death worldwide. The pathological development of ASCVD begins with atherosclerosis, characterised by a pathological remodelling of the arterial wall, lipid accumulation and build-up of atheromatous plaque. As the disease advances, it narrows the vascular lumen and limits the blood, leading to ischaemic necrosis in coronary arteries. Exosomes are nano-sized lipid vesicles of different origins that can carry many bioactive molecules from their parental cells, thus playing an important role in intercellular communication. The roles of exosomes in atherosclerosis have recently been intensively studied, advancing our understanding of the underlying molecular mechanisms. In this review, we briefly introduce exosome biology and then focus on the roles of exosomes of different cellular origins in atherosclerosis development and progression, functional significance of their cargoes and physiological impact on recipient cells. Studies have demonstrated that exosomes originating from endothelial cells, vascular smooth muscle cells, macrophages, dendritic cells, platelets, stem cells, adipose tissue and other sources play an important role in the atherosclerosis development and progression by affecting cholesterol transport, inflammatory, apoptotic and other aspects of the recipient cells' metabolism. MicroRNAs are considered the most significant type of bioactive molecules transported by exosomes and involved in ASCVD development. Finally, we review the current achievements and limitations associated with the use of exosomes for the diagnosis and treatment of ASCVD.

Role of ABCA1 in Atherosclerosis: Novel Mutations and Potential Plant-derived Therapies.

ATP-binding cassette transporter A1 (ABCA1) is one of the key proteins regulating cholesterol homeostasis and playing a crucial role in atherosclerosis development. ABCA1 regulates the rate-limiting step of reverse cholesterol transport, facilitates the efflux of surplus intracellular cholesterol and phospholipids, and suppresses inflammation through several signalling pathways. At the same time, many mutations and Single Nucleotide Polymorphisms (SNPs) have been identified in the ABCA1 gene, which affects its biological function and is associated with several hereditary diseases (such as familial hypo-alpha-lipoproteinaemia and Tangier disease) and increased risk of cardiovascular diseases (CVDs). This review summarises recently identified mutations and SNPs in their connection to atherosclerosis and associated CVDs. Also, we discuss the recently described application of various plant-derived compounds to modulate ABCA1 expression in different in vitro and in vivo models. Herein, we present a comprehensive overview of the association of ABCA1 mutations and SNPs with CVDs and as a pharmacological target for different natural-derived compounds and highlight the potential application of these phytochemicals for treating atherosclerosis through modulation of ABCA1 expression.

Lipids and Lipoproteins in Atherosclerosis.

Atherosclerosis is a chronic inflammatory disease [...].

Thirty-Five-Year History of Desialylated Lipoproteins Discovered by Vladimir Tertov.

Atherosclerosis is one of the leading causes of death in developed and developing countries. The atherogenicity phenomenon cannot be separated from the role of modified low-density lipoproteins (LDL) in atherosclerosis development. Among the multiple modifications of LDL, desialylation deserves to be discussed separately, since its atherogenic effects and contribution to atherogenicity are often underestimated or, simply, forgotten. Vladimir Tertov is linked to the origin of the research related to desialylated lipoproteins, including the association of modified LDL with atherogenicity, autoimmune nature of atherosclerosis, and discovery of sialidase activity in blood plasma. The review will briefly discuss all the above-mentioned information, with a description of the current situation in the research.

Mitochondrial Antioxidant SkQ1 Has a Beneficial Effect in Experimental Diabetes as Based on the Analysis of Expression of microRNAs and mRNAs for the Oxidative Metabolism Regulators.

Diabetes mellitus and related complications are among the most important problems of the world-leading healthcare systems. Despite their priority, molecular and genetic aspects of diabetes pathogenesis are poorly understood; however, the involvement of oxidative stress in this process is undoubted. Rats with experimental diabetes induced by the intraperitoneal injection of alloxan were subjected to the antioxidant pre-therapy with a series of mitochondria-targeted 10-(6'-plastoquinonyl)decyltriphenylphosphonium (SkQ1) injections and analyzed for the expression of mRNAs and microRNAs by real-time quantitative polymerase chain reaction to identify potential predictors of diabetes. Animals that received SkQ1 before diabetes induction demonstrated lower blood glucose levels compared to the diabetic animals not subjected to the therapy. SkQ1 caused changes in the mRNA levels of genes involved in the cellular defense against free radicals, which indicates a beneficial effect of the pre-therapy. Moreover, similar changes were observed on the epigenetic level, as the microRNA expression patterns not only proved the SkQ1 efficacy but also correlated with the expression levels of their mRNA targets. Oxidative stress and macromolecule damage by free radicals are determining factors in diabetes, which suggests that strategies aimed at restoring the antioxidant status of the cell can be beneficial. Mitochondria-targeted antioxidant SkQ1 demonstrates positive effects on several levels, from the normalization of the blood glucose content to genetic and epigenetic changes. Our results can serve as a basis for the development of novel therapeutic and diagnostic strategies.

Prospects for the Use of Sialidase Inhibitors in Anti-atherosclerotic Therapy.

The most typical feature of atherogenesis in humans at its early stage is the formation of foam cells in subendothelial arterial intima, which occurs as the consequence of intracellular cholesterol deposition. The main source of lipids accumulating in the arterial wall is circulating low-density lipoprotein (LDL). However, LDL particles should undergo proatherogenic modification to acquire atherogenic properties. One of the known types of atherogenic modification of LDL is enzymatic deglycosilation, namely, desialylation, which is the earliest change in the cascade of following multiple LDL modifications. The accumulating data make sialidases an intriguing and plausible therapeutic target, since pharmacological modulation of activity of these enzymes may have beneficial effects in several pathologies, including atherosclerosis. The hypothesis exists that decreasing LDL enzymatic desialylation may result in the prevention of lipid accumulation in arterial wall, thus breaking down one of the key players in atherogenesis at the cellular level. Several drugs acting as glycomimetics and inhibiting sialidase enzymatic activity already exist, but the concept of sialidase inhibition as an anti-atherosclerosis strategy remains unexplored to date. This review is focused on the potential possibilities of the repurposing of sialidase inhibitors for pathogenetic anti-atherosclerotic therapy.

Sialylated Immunoglobulins for the Treatment of Immuno-Inflammatory Diseases.

Immunoglobulins are the potent effector proteins of the humoral immune response. In the course of evolution, immunoglobulins have formed extremely diverse types of molecular structures with antigen-recognizing, antigen-binding, and effector functions embedded in a single molecule. Polysaccharide moiety of immunoglobulins plays the essential role in immunoglobulin functioning. There is growing evidence that the carbohydrate composition of immunoglobulin-linked glycans, and especially their terminal sialic acid residues, provide a key effect on the effector functions of immunoglobulins. Possibly, sialylation of Fc glycan is a common mechanism of IgG anti-inflammatory action in vivo. Thus, the post-translational modification (glycosylation) of immunoglobulins opens up significant possibilities in the diagnosis of both immunological and inflammatory disorders and in their therapies. This review is focused on the analysis of glycosylation of immunoglobulins, which can be a promising addition to improve existing strategies for the diagnosis and treatment of various immuno-inflammatory diseases.

Sialidase Activity in Human Blood Serum Has a Distinct Seasonal Pattern: A Pilot Study.

Desialylation-loss of terminal sialic acid residues from glycoconjugates catalyzed by sialidases-is involved in many human diseases and is considered a key molecular event of atherosclerosis onset. Desialylated low-density lipoproteins with atherogenic properties have been detected in human blood previously. However, there is currently no consensus on the origin of desialylation activity in the bloodstream. Here, we suggest viral intervention as a possible explanation. In order to address our hypothesis, we studied seasonal patterns of blood serum sialidase enzymatic activity and designed an approach to detect and quantify viral sialidase genetic presence. Increased sialidase activity in autumn-winter combined with detectable levels of influenza virus sialidase mRNA suggests exogenous viral sialidase as a viable component of desialylation in human blood, providing new insights on the molecular background of atherogenesis.

The role of mitochondria in cardiovascular diseases related to atherosclerosis.

Atherosclerosis is a complex disorder that involves several mechanisms of pathogenesis tightly related to each other: lipid accumulation, inflammation and structural changes in the arterial wall. The main source of lipids accumulating in the arterial wall is low-density lipoprotein (LDL) atherogenically modified by desialylation or oxidation. Oxidized LDL can be produced as a result of enhanced generation of reactive oxygen species by mitochondria during oxidative stress. Mitochondrial dysfunction was found to be involved in every aspect of atherosclerosis, and is currently evaluated as a potential point of therapeutic intervention. In particular, atherosclerosis-associated inflammation and its link to mitochondrial dysfunction appear to be interesting, since mitochondria not only trigger the response to external signals, but also can act as pro-inflammatory agents themselves. In this regard, atherosclerosis is potentially an autoimmune disease. In this review, we summarize recent insights on the role of mitochondrial dysfunction in atherogenesis and discuss the significance of mitochondria for understanding of molecular basis of cardiovascular diseases.

Trans-sialidase Associated with Atherosclerosis: Defining the Identity of a Key Enzyme Involved in the Pathology.

Atherosclerosis is associated with the increased trans-sialidase activity, which can be detected in the blood plasma of atherosclerosis patients. The likely involvement in the disease pathogenesis made this activity an interesting research subject and the enzyme that may perform such activity was isolated and characterized in terms of substrate specificity and enzymatic properties. It was found that the enzyme has distinct optimum pH values, and its activity was enhanced by the presence of Ca2+ ions. Most importantly, the enzyme was able to cause atherogenic modification of lowdensity lipoprotein (LDL) particles in vitro. However, the identity of the discovered enzyme remained to be defined. Currently, sialyltransferases, mainly ST6Gal I, are regarded as major contributors to sialic acid metabolism in human blood. In this mini-review, we discuss the possibility that atherosclerosis- associated trans-sialidase does, in fact, belong to the sialyltransferases family.

Transcriptional Characteristics of Activated Macrophages.

Macrophages are key players in human innate immunity that protect the organism from pathologic agents, including infection and malignant cells. The spectrum of their functions includes initiation and maintaining of inflammation, cleaning of pathogens and cell debris, as well as inflammation resolution and tissue remodeling and repair. Such a wide spectrum is reflected by the great variety of macrophage phenotypes based on the activation of distinct transcription patterns in response to different stimuli. Studying this complexity requires an integrated approach, such as transcriptome studies. For many genes, the exact role in macrophage biology remains unknown, although clear associations with pro- or anti-inflammatory macrophage polarization could be demonstrated. These findings reveal the novel directions for future research. In this review, we describe the known mechanisms of macrophage polarization and the new insights available from transcriptome studies.

Sialidase activity in human pathologies.

Sialic acid residues are frequently located at the terminal positions of glycoconjugate chains of cellular glycocalyx. Sialidases, or neuraminidases, catalyse removal of these residues thereby modulating various normal and pathological cellular activities. Recent studies have revealed the involvement of sialidases in a wide range of human disorders, including neurodegenerative disorders, cancers, infectious diseases and cardiovascular diseases. The accumulating data make sialidases an interesting potential therapeutic target. Modulating the activity of these enzymes may have beneficial effects in several pathologies. Four types of mammalian sialidases have been described: NEU1, NEU2, NEU3 and NEU4. They are encoded by different genes and characterized by different subcellular localization. In this review, we will summarize the current knowledge on the roles of different sialidases in pathological conditions.

Inhibition of sialidase activity as a therapeutic approach.

The demand for novel anti-influenza drugs persists, which is highlighted by the recent pandemics of influenza affecting thousands of people across the globe. One of the approaches to block the virus spreading is inhibiting viral sialidase (neuraminidase). This enzyme cleaves the sialic acid link between the newly formed virions and the host cell surface liberating the virions from the cell and maintaining the cycle of infection. Viral neuraminidases appear therefore as attractive therapeutic targets for preventing further spread of influenza infection. Compared to ion channel blockers that were the first approved anti-influenza drugs, neuraminidase inhibitors are well tolerated and target both influenza A and B viruses. Moreover, neuraminidase/sialidase inhibitors may be useful for managing some other human pathologies, such as cancer. In this review, we discuss the available knowledge on neuraminidase or sialidase inhibitors, their design, clinical application, and the current challenges.

Human Disease Modelling Techniques: Current Progress.

Advances in genetic engineering and genomic studies facilitated the development of animal models of human diseases. To date, numerous models based on different animal species are available for the most socially significant human diseases, such as cardiovascular disorders, cancer, neurodegenerative and metabolic disorders. Modern genetic methods allow creating animals with certain genes up- or downregulated, as well as bearing specific mutations. However, this precision is not easy to translate into clinical practice: animal models still have their limitations, including both physiological and genetic differences between humans and animals and complexity of disease conditions that are difficult to reproduce. In this review, we will discuss the most relevant modern techniques that allow creating genetically engineered animal models.