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

Development of hydrogen sulfide donors for anti-atherosclerosis therapeutics research: Challenges and future priorities

Hydrogen sulfide (H₂S), a gas transmitter found in eukaryotic organisms, plays an essential role in several physiological processes. H₂S is one of the three primary biological gas transmission signaling mediators, along with nitric oxide and carbon monoxide. Several animal and in vitro experiments have indicated that H₂S can prevent coronary endothelial mesenchymal transition, reduce the expression of endothelial cell adhesion molecules, and stabilize intravascular plaques, suggesting its potential role in the treatment of atherosclerosis (AS). H₂S donors are compounds that can release H₂S under certain circumstances. Development of highly targeted H₂S donors is a key imperative as these can allow for in-depth evaluation of the anti-atherosclerotic effects of exogenous H₂S. More importantly, identification of an optimal H₂S donor is critical for the creation of H₂S anti-atherosclerotic prodrugs. In this review, we discuss a wide range of H₂S donors with anti-AS potential along with their respective transport pathways and design-related limitations. We also discuss the utilization of nano-synthetic technologies to manufacture H₂S donors. This innovative and effective design example sheds new light on the production of highly targeted H₂S donors.

Selective Boosting of CCR7-Acting Chemokines; Short Peptides Boost Chemokines with Short Basic Tails, Longer Peptides Boost Chemokines with Long Basic Tails

The chemokine receptor CCR7 and its ligands CCL19 and CCL21 regulate the lymph node homing of dendritic cells and naïve T-cells and the following induction of a motile DC-T cell priming state. Although CCL19 and CCL21 bind CCR7 with similar affinities, CCL21 is a weak agonist compared to CCL19. Using a chimeric chemokine, CCL19^{CCL21N-term|C-term}, harboring the N-terminus and the C-terminus of CCL21 attached to the core domain of CCL19, we show that these parts of CCL21 act in a synergistic manner to lower ligand potency and determine the way CCL21 engages with CCR7. We have published that a naturally occurring basic C-terminal fragment of CCL21 (C21TP) boosts the signaling of both CCL19 and CCL21. Boosting occurs as a direct consequence of C21TP binding to the CCR7 N-terminus, which seems to free chemokines with basic C-termini from an unfavorable interaction with negatively charged posttranslational modifications in CCR7. Here, we confirm this using a CCL19-variant lacking the basic C-terminus. This variant displays a 22-fold higher potency at CCR7 compared to WT CCL19 and is highly unaffected by the presence of C21TP. WT CCL19 has a short basic C-terminus, CCL21 a longer one. Here, we propose a way to differentially boost CCL19 and CCL21 activity as short and long versions of C21TP boost CCL19 activity, whereas only a long C21TP version can boost chemokines with a full-length CCL21 C-terminus.

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.

Proatherogenic Sialidases and Desialylated Lipoproteins: 35 Years of Research and Current State from Bench to Bedside

This review summarizes the main achievements in basic and clinical research of atherosclerosis. Focusing on desialylation as the first and the most important reaction of proatherogenic pathological cascade, we speak of how desialylation increases the atherogenic properties of low density lipoproteins and decreases the anti-atherogenic properties of high density lipoproteins. The separate sections of this paper are devoted to immunogenicity of lipoproteins, the enzymes contributing to their desialylation and animal models of atherosclerosis. In addition, we evaluate the available experimental and diagnostic protocols that can be used to develop new therapeutic approaches for atherosclerosis.

The Role of Sialic Acids in the Establishment of Infections by Pathogens, With Special Focus on Leishmania

Carbohydrates or glycans are ubiquitous components of the cell surface which play crucial biological and structural roles. Sialic acids (Sias) are nine-carbon atoms sugars usually present as terminal residues of glycoproteins and glycolipids on the cell surface or secreted. They have important roles in cellular communication and also in infection and survival of pathogens. More than 20 pathogens can synthesize or capture Sias from their hosts and incorporate them into their own glycoconjugates and derivatives. Sialylation of pathogens’ glycoconjugates may be crucial for survival inside the host for numerous reasons. The role of Sias in protozoa such as Trypanosoma and Leishmania was demonstrated in previous studies. This review highlights the importance of Sias in several pathogenic infections, focusing on Leishmania. We describe in detail the contributions of Sias, Siglecs (sialic acid binding Ig-like lectins) and Neuraminidase 1 (NEU 1) in the course of Leishmania infection. A detailed view on the structural and functional diversity of Leishmania-related Sias and host-cell receptors will be provided, as well as the results of functional studies performed with different Leishmania species.