Extracellular microRNAs (miRNAs) are uniquely stable in plasma, and the levels of specific circulating miRNAs can differ with disease. Extracellular miRNAs are associated with lipid-based carriers ...and lipid-free proteins. miRNAs can be transferred from cell-to-cell by lipid-based carriers and affect gene expression. This review summarizes recent studies that demonstrate the transfer of miRNA between cells and their potential role in intercellular communication.
Microvesicles, exosomes, apoptotic bodies, lipoproteins, and large microparticles contain miRNAs. Recent studies have demonstrated that miRNAs are transferred between dendritic cells, hepatocellular carcinoma cells, and adipocytes in lipid-based carriers. miRNAs are also transferred from T cells to antigen-presenting cells, from stem cells to endothelial cells and fibroblasts, from macrophages to breast cancer cells, and from epithelial cells to hepatocytes in lipid-based carriers. The cellular export of miRNAs in lipid-based carriers is regulated by the ceramide pathway, and the delivery of lipid-associated miRNAs to recipient cells is achieved by various routes, including endocytotic uptake, membrane-fusion, and scavenger receptors.
Cellular miRNAs are exported in and to lipid-based carriers (vesicles and lipoprotein particles) and transferred to recipient cells with gene expression changes as intercellular communication.
Cholesterol on low-density lipoproteins (LDL-C) is one of the main drivers of atherosclerotic cardiovascular disease (ASCVD) and hence its measurement is critical in the management of patients at ...risk. Although LDL-C has routinely been either calculated by the Friedewald equation or measured with direct assays, these methods have limitations, particularly for patients with dyslipidaemias, low LDL-C, and hypertriglyceridemia. The focus of this review will be recent advances in the measurement of LDL for ASCVD risk management.
We first describe the recent recommendations on how LDL-C is used in ASCVD risk assessment and management. We then review the current approaches to the measurement of LDL-C and recent developments on new more accurate equations for calculating LDL-C. Finally, we present new and emerging LDL assays that may be superior to LDL-C for risk assessment, such as LDL particle number and small dense LDL-C, and several LDL-based lipid tests in early development.
LDL-C is valuable in ASCVD risk management but recent improvements in its measurement and the development of other LDL-related tests may further improve its value.
Low high-density lipoprotein cholesterol (HDL-C) characterizes an atherogenic dyslipidemia that reflects adverse lifestyle choices, impaired metabolism, and increased cardiovascular risk. Low HDL-C ...is also associated with increased risk of inflammatory disorders, malignancy, diabetes, and other diseases. This epidemiologic evidence has not translated to raising HDL-C as a viable therapeutic target, partly because HDL-C does not reflect high-density lipoprotein (HDL) function. Mendelian randomization analyses that have found no evidence of a causal relationship between HDL-C levels and cardiovascular risk have decreased interest in increasing HDL-C levels as a therapeutic target. HDLs comprise distinct subpopulations of particles of varying size, charge, and composition that have several dynamic and context-dependent functions, especially with respect to acute and chronic inflammatory states. These functions include reverse cholesterol transport, inhibition of inflammation and oxidation, and antidiabetic properties. HDLs can be anti-inflammatory (which may protect against atherosclerosis and diabetes) and proinflammatory (which may help clear pathogens in sepsis). The molecular regulation of HDLs is complex, as evidenced by their association with multiple proteins, as well as bioactive lipids and noncoding RNAs. Clinical investigations of HDL biomarkers (HDL-C, HDL particle number, and apolipoprotein A through I) have revealed nonlinear relationships with cardiovascular outcomes, differential relationships by sex and ethnicity, and differential patterns with coronary versus noncoronary events. Novel HDL markers may also have relevance for heart failure, cancer, and diabetes. HDL function markers (namely, cholesterol efflux capacity) are associated with coronary disease, but they remain research tools. Therapeutics that manipulate aspects of HDL metabolism remain the holy grail. None has proven to be successful, but most have targeted HDL-C, not metrics of HDL function. Future therapeutic strategies should focus on optimizing HDL function in the right patients at the optimal time in their disease course. We provide a framework to help the research and clinical communities, as well as funding agencies and stakeholders, obtain insights into current thinking on these topics, and what we predict will be an exciting future for research and development on HDLs.
Graphical Abstract
Graphical Abstract
The great complexity of HDL. High-density lipoprotein (HDL) particles carry a large number of proteins and lipids, which contribute to define their compositional ...and functional complexity. HDLs exert multiple protective activities, essentially by three major mechanisms. HDLs, however, can lose their protective functions and even gain adverse functions in chronic diseases or during infections. U-shaped relationships between HDL-cholesterol (HDL-C) levels and several conditions have been reported, being both low and extremely high HDL-C levels associated with an increased risk of several pathologies and mortality. LCAT, lecithin:cholesterol acyltransferase; CETP, cholesteryl ester transfer protein; PONI, paraoxonase 1; S1P, sphingosine-1-phosphate; ASCVD, atherosclerotic cardiovascular disease; LDL, low-density lipoprotein; SAA, serum amyloid A; OxPL, oxidized phospholipids
Abstract
Previous interest in high-density lipoproteins (HDLs) focused on their possible protective role in atherosclerotic cardiovascular disease (ASCVD). Evidence from genetic studies and randomized trials, however, questioned that the inverse association of HDL-cholesterol (HDL-C) is causal. This review aims to provide an update on the role of HDL in health and disease, also beyond ASCVD. Through evolution from invertebrates, HDLs are the principal lipoproteins, while apolipoprotein B-containing lipoproteins first developed in vertebrates. HDLs transport cholesterol and other lipids between different cells like a reusable ferry, but serve many other functions including communication with cells and the inactivation of biohazards like bacterial lipopolysaccharides. These functions are exerted by entire HDL particles or distinct proteins or lipids carried by HDL rather than by its cholesterol cargo measured as HDL-C. Neither does HDL-C measurement reflect the efficiency of reverse cholesterol transport. Recent studies indicate that functional measures of HDL, notably cholesterol efflux capacity, numbers of HDL particles, or distinct HDL proteins are better predictors of ASCVD events than HDL-C. Low HDL-C levels are related observationally, but also genetically, to increased risks of infectious diseases, death during sepsis, diabetes mellitus, and chronic kidney disease. Additional, but only observational, data indicate associations of low HDL-C with various autoimmune diseases, and cancers, as well as all-cause mortality. Conversely, extremely high HDL-C levels are associated with an increased risk of age-related macular degeneration (also genetically), infectious disease, and all-cause mortality. HDL encompasses dynamic multimolecular and multifunctional lipoproteins that likely emerged during evolution to serve several physiological roles and prevent or heal pathologies beyond ASCVD. For any clinical exploitation of HDL, the indirect marker HDL-C must be replaced by direct biomarkers reflecting the causal role of HDL in the respective disease.
Drug repurposing is potentially the fastest available option in the race to identify safe and efficacious drugs that can be used to prevent and/or treat COVID‐19. By describing the life cycle of the ...newly emergent coronavirus, SARS‐CoV‐2, in light of emerging data on the therapeutic efficacy of various repurposed antimicrobials undergoing testing against the virus, we highlight in this review a possible mechanistic convergence between some of these tested compounds. Specifically, we propose that the lysosomotropic effects of hydroxychloroquine and several other drugs undergoing testing may be responsible for their demonstrated in vitro antiviral activities against COVID‐19. Moreover, we propose that Niemann‐Pick disease type C (NPC), a lysosomal storage disorder, may provide new insights into potential future therapeutic targets for SARS‐CoV‐2, by highlighting key established features of the disorder that together result in an “unfavorable” host cellular environment that may interfere with viral propagation. Our reasoning evolves from previous biochemical and cell biology findings related to NPC, coupled with the rapidly evolving data on COVID‐19. Our overall aim is to suggest that pharmacological interventions targeting lysosomal function in general, and those particularly capable of reversibly inducing transient NPC‐like cellular and biochemical phenotypes, constitute plausible mechanisms that could be used to therapeutically target COVID‐19.
Can "Bad" HDL Be Turned Good Again? Dasseux, Amaury; Remaley, Alan T
Arteriosclerosis, thrombosis, and vascular biology,
06/2023, Letnik:
43, Številka:
6
Journal Article
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