The formation and consequences of cholesterol-rich deposits in atherosclerotic lesions

Zebrafish navigating the metabolic maze: insights into human disease - assets, challenges and future implications

Zebrafish (Danio rerio) have become indispensable models for advancing our understanding of multiple metabolic disorders such as obesity, diabetes mellitus, dyslipidemia, and metabolic syndrome. This review provides a comprehensive analysis of zebrafish as a powerful tool for dissecting the genetic and molecular mechanisms of these diseases, focusing on key genes, like pparγ, lepr, ins, and srebp. Zebrafish offer distinct advantages, including genetic tractability, optical transparency in early development, and the conservation of key metabolic pathways with humans. Studies have successfully used zebrafish to uncover conserved metabolic mechanisms, identify novel disease pathways, and facilitate high-throughput screening of potential therapeutic compounds. The review also highlights the novelty of using zebrafish to model multifactorial metabolic disorders, addressing challenges such as interspecies differences in metabolism and the complexity of human metabolic disease etiology. Moving forward, future research will benefit from integrating advanced omics technologies to map disease-specific molecular signatures, applying personalized medicine approaches to optimize treatments, and utilizing computational models to predict therapeutic outcomes. By embracing these innovative strategies, zebrafish research has the potential to revolutionize the diagnosis, treatment, and prevention of metabolic disorders, offering new avenues for translational applications. Continued interdisciplinary collaboration and investment in zebrafish-based studies will be crucial to fully harnessing their potential for advancing therapeutic development.

Microglia degrade Alzheimer's amyloid-beta deposits extracellularly via digestive exophagy

How microglia digest Alzheimer's fibrillar amyloid-beta (Aβ) plaques that are too large to be phagocytosed is not well understood. Here, we show that primary microglial cells create acidic extracellular compartments, lysosomal synapses, on model plaques and digest them with exocytosed lysosomal enzymes. This mechanism, called digestive exophagy, is confirmed by electron microscopy in 5xFAD mouse brains, which shows that a lysosomal enzyme, acid phosphatase, is secreted toward the plaques in structures resembling lysosomal synapses. Signaling studies demonstrate that the PI3K-AKT pathway modulates the formation of lysosomal synapses, as inhibition of PI3K1β or AKT1/2 reduces both lysosome exocytosis and actin polymerization, both required for the formation of the compartments. Finally, we show that small fibrils of Aβ previously internalized and trafficked to lysosomes are exocytosed toward large Aβ aggregates by microglia. Thus, the release of lysosomal contents during digestive exophagy may also contribute to the spread and growth of fibrillar Aβ.

Reduced Intra- and Extracellular Circulating Postprandial Lysosomal Acid Lipase Activity in Patients with MASLD

BACKGROUND/OBJECTIVES

Low fasting blood lysosomal acid lipase (LAL) activity is associated with the pathogenesis of metabolic hepatic steatosis. We measured LAL activity in blood and plasma before and after an oral fat tolerance test (OFTT) in patients with metabolic-dysfunction-associated steatotic liver disease (MASLD).

METHODS

Twenty-six controls and seventeen patients with MASLD but without diabetes were genotyped for the patatin-like phospholipase 3 (PNPLA3) rs738409 variant by RT-PCR and subjected to an OFTT, measuring LAL activity in blood and plasma with a fluorimetric method.

RESULTS

LAL activity in blood both under fasting and 4 h after OFTT (0.846 ± 0.309 nmol/spot/h vs. 1.180 ± 0.503 nmol/spot/h p < 0.01) was lower in patients with MASLD compared to controls. These differences were present only in carriers of the PNPLA3 variant. In controls not carrying the PNPLA3 variant, the postprandial increase in blood LAL activity was negatively correlated with that of serum triglycerides (p < 0.05). Extracellular LAL activity in plasma was lower in patients with MASLD (n = 9) compared to controls (n = 8) in the fasting state (p < 0.01) and 4 h post-meal (p < 0.05). The area under the curve up to 6 h of plasma LAL activity was lower in patients with MASLD than in controls (p < 0.05) and correlated negatively with that of triglycerides only in controls (r = -0.841; p < 0.01).

CONCLUSIONS

Patients with MASLD have reduced LAL activity in blood and plasma both before and 4 h after a meal. In patients with MASLD, the physiological negative correlation between circulating LAL levels and postprandial hypertriglyceridemia is lost.

Identifying the key role of mitochondrial respiration and lipid metabolism in regulating axillary osmidrosis through proteomics analysis

Axillary osmidrosis (AO) affects a large number of young people in Asia, resulting from a combination of body and bacterial metabolism. This study aimed to explore the pathogenesis of AO through proteomics. Apocrine gland tissues from 3 mild and 3 severe AO patients were analyzed using 4D label-free proteomics, followed by bioinformatics analysis. The RNA and protein levels of the predicted key regulators were further validated by qPCR and immunohistochemistry in additional AO tissues. A total of 5066 proteins were identified, of which 323 were significantly upregulated and 412 were downregulated (by |log2FC|> 1 and p < 0.05). GO terms related to mitochondria, oxidation-reduction processes, and peroxisomes were significantly enriched among the upregulated DEPs, suggesting enhanced energy metabolism in severe AO patients. Downregulated DEPs were enriched in ribosome, phagosome, and platelet activation pathways according to KEGG, while upregulated DEPs were significantly enriched in metabolic pathways, valine, leucine, and isoleucine degradation, peroxisomes, and fatty acid degradation. The enriched pathways suggest that apocrine gland tissues develop AO by increasing blood flow to promote sweating and secreting excessive short-chain fatty acids by coupling mitochondrial respiration with incomplete metabolism of lipids and branched-chain amino acids. This metabolic coupling may have implications for studies on cardiovascular disease, metabolic disorders, and oxidative stress. Key proteins in the signaling network were further confirmed by qPCR and immunohistochemistry, including reduced FGA and ITGA2B, and increased EHHADH and ACOX1. Our proteomics analysis suggests a paradigm of lipid metabolism involving mitochondrial respiration and incomplete lipid and branched-chain amino acid metabolism as the pathogenesis of AO. We also suggest that EHHADH is a key regulator in promoting AO in this process.

A high-content microscopy drug screening platform for regulators of the extracellular digestion of lipoprotein aggregates by macrophages

The recruitment of macrophages to the intima of arteries is a critical event in atherosclerotic progression. These macrophages accumulate excessive lipid droplets and become "foam cells", a hallmark of atherosclerosis. Most studies focus on lipid accumulation through macrophage interaction with modified monomeric low-density lipoprotein (LDL). However, in the intima, macrophages predominantly encounter aggregated LDL (agLDL), an interaction that has been studied far less. Macrophages digest agLDL and generate free cholesterol in an extracellular, acidic, hydrolytic compartment. They form a tight seal around agLDL through actin polymerization and deliver lysosomal contents into this space in a process termed digestive exophagy. There is some evidence that inhibiting digestive exophagy to slow cholesterol accumulation in macrophages protects them from becoming foam cells and slows the progression of atherosclerotic lesions. Thus, understanding the mechanisms of digestive exophagy is critical. Here, we describe a high-content microscopy screen on a library of repurposed drugs for compounds that inhibit lysosome exocytosis during digestive exophagy. We identified many hit compounds and further characterized the effects that five of these compounds have on various aspects of digestive exophagy. In addition, three of the five compounds do not inhibit oxidized LDL-induced foam cell formation, indicating the two pathways to foam cell formation can be targeted independently. We demonstrate that this high-content screening platform has great potential as a drug discovery tool with the ability to effectively and efficiently screen for modulators of digestive exophagy.

Vascular Extracellular Matrix in Atherosclerosis

The extracellular matrix (ECM) plays a central role in the structural integrity and functionality of the cardiovascular system. Moreover, the ECM is involved in atherosclerotic plaque formation and stability. In fact, ECM remodeling affects plaque stability, cellular migration, and inflammatory responses. Collagens, fibronectin, laminin, elastin, and proteoglycans are crucial proteins during atherosclerosis development. This dynamic remodeling is driven by proteolytic enzymes such as matrix metalloproteinases (MMPs), cathepsins, and serine proteases. Exploring and investigating ECM dynamics is an important step to designing innovative therapeutic strategies targeting ECM remodeling mechanisms, thus offering significant advantages in the management of cardiovascular diseases. This review illustrates the structure and role of vascular ECM, presenting a new perspective on ECM remodeling and its potential as a therapeutic target in atherosclerosis treatments.

A cross-sectional study of factors associated with carotid atherosclerosis

Objective

The aim of this work was to study the relationship between carotid atherosclerosis (CAS) and several indexes and provide a basis for the prevention and treatment of cardiovascular and cerebrovascular diseases.

Methods

There were 11,028 adults who underwent physical examination at the Guangzhou Cadre and Talent Health Management Center from January 2023 to December 2023 and were selected as research subjects. Retrospective analysis was used to understand the carotid atherosclerosis of the examined population and analyze its relationship with sex, age, blood pressure, blood glucose, blood lipids, renal function, 25-hydroxyvitamin D, neutrophil to lymphocyte count ratio (NLR), platelet to lymphocyte count ratio (PLR), systemic immune inflammation index (SII), monocyte count to high-density lipoprotein cholesterol ratio (MHR), triglyceride glucose body mass index (TyG-BMI), insulin resistance metabolic index (METS-IR), and other indicators.

Results

Among 11,028 subjects, the detection rate of carotid atherosclerotic thickening (CAT) was 12.00% and carotid atherosclerotic plaque (CAP) was 25.11%. The CAT and CAP detection rates in men were 13.32% and 28.78%, respectively, which were higher than the CAT detection rate of 8.28% and CAP detection rate of 14.80% in women, and the differences were statistically significant (both p < 0.001). Multivariate logistic regression analysis using TyG-BMI and METS-IR as two indicators was modeled separately, and the results showed that CAS was associated with men, increasing age, and systolic blood pressure. The area under the curve (AUC) was analyzed using the subject's work characteristic (ROC) curve in the descending order of METS-IR, TyG-BMI, and MHR. The combination of the three indexes of sex, age, and METS-IR predicted atherosclerosis with the highest AUC values.

Conclusion

Carotid atherosclerosis is highly prevalent in men. Elevation of systolic blood pressure, fasting glucose, MHR, and TyG-BMI (or METS-IR) with age are independent influences on carotid atherosclerosis. The three indexes of MHR, TyG-BMI, and METS-IR, respectively, in combination with sex and age, can be used as a new and effective index to predict CAS.

Effect of diet and genotype on the lipidome of mice with altered lipoprotein metabolism

The present study describes and compares the impact of PCSK9 and LDLR, two pivotal players in cholesterol metabolism, on the whole lipidome of plasma, liver and aorta in different dietary conditions. This issue is relevant, since several lipid species, circulating at very low concentrations, have the ability to impair lipid metabolism and promote atherosclerosis development. To this aim, wild-type, hypercholesterolemic Ldlr-KO, and hypocholesterolemic Pcsk9-KO mice were fed a standard chow or a Western-type diet up to 30 and 16 weeks of age, respectively. 42 lipids including cholesterol, cholesteryl esters, several sphingolipids, phospholipids, and lysophospholipids, accumulated uniquely in the atherosclerotic aorta of Western-type diet-fed Ldlr-KO mice. In addition, multiple organ/tissue comparisons allowed us to identify 16 lipids whose plasma and hepatic patterns mirrored the lipidome of the atherosclerotic aorta. These lipid species, belonging to cholesteryl esters, glucosyl/galactosylceramide, lactosylceramide, globotriaosylceramide, sphingomyelin, and phosphatidylcholine could be further investigated as circulating biomarkers or therapeutic targets.

Cholesterol trafficking, lysosomal function, and atherosclerosis

Despite years of study and major research advances over the past 50 years, atherosclerotic diseases continue to rank as the leading global cause of death. Accumulation of cholesterol within the vascular wall remains the main problem and represents one of the early steps in the development of atherosclerotic lesions. There is a complex relationship between vesicular cholesterol transport and atherosclerosis, and abnormalities in cholesterol trafficking can contribute to the development and progression of the lesions. The dysregulation of vesicular cholesterol transport and lysosomal function fosters the buildup of cholesterol within various intracytoplasmic compartments, including lysosomes and lipid droplets. This, in turn, promotes the hallmark formation of foam cells, a defining feature of early atherosclerosis. Multiple cellular processes, encompassing endocytosis, exocytosis, intracellular trafficking, and autophagy, play crucial roles in influencing foam cell formation and atherosclerotic plaque stability. In this review, we highlight recent advances in the understanding of the intricate mechanisms of vesicular cholesterol transport and its relationship with atherosclerosis and discuss the importance of understanding these mechanisms in developing strategies to prevent or treat this prevalent cardiovascular disease.

Signaling pathways regulating the extracellular digestion of lipoprotein aggregates by macrophages

The interaction between aggregated low-density lipoprotein (agLDL) and macrophages in arteries plays a major role in atherosclerosis. Macrophages digest agLDL and generate free cholesterol in an extracellular, acidic, hydrolytic compartment known as the lysosomal synapse. Macrophages form a tight seal around agLDL through actin polymerization and deliver lysosomal contents into this space in a process termed digestive exophagy. Our laboratory has identified TLR4 activation of MyD88/Syk as critical for digestive exophagy. Here we use pharmacological agents and siRNA knockdown to characterize signaling pathways downstream of Syk that are involved in digestive exophagy. Syk activates Bruton's tyrosine kinase (BTK) and phospholipase Cγ2 (PLCγ2). We show that PLCγ2 and to a lesser extent BTK regulate digestive exophagy. PLCγ2 cleaves PI(4,5)P2 into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). Soluble IP3 activates release of Ca2+ from the endoplasmic reticulum (ER). We demonstrate that Ca2+ release from the ER is upregulated by agLDL and plays a key role in digestive exophagy. Both DAG and Ca2+ activate protein kinase Cα (PKCα). We find that PKCα is an important regulator of digestive exophagy. These results expand our understanding of the mechanisms of digestive exophagy, which could be useful in developing therapeutic interventions to slow development of atherosclerosis.

Exploring the role of cyclodextrins as a cholesterol scavenger: a molecular dynamics investigation of conformational changes and thermodynamics

This study presents a comprehensive analysis of the cholesterol binding mechanism and conformational changes in cyclodextrin (CD) carriers, namely βCD, 2HPβCD, and MβCD. The results revealed that the binding of cholesterol to CDs was spontaneous and thermodynamically favorable, with van der Waals interactions playing a dominant role, while Coulombic interactions have a negligible contribution. The solubility of cholesterol/βCD and cholesterol/MβCD complexes was lower compared to cholesterol/2HPβCD complex due to stronger vdW and Coulombic repulsion between water and CDs. Hydrogen bonding was found to have a minor role in the binding process. The investigation of mechanisms and kinetics of binding demonstrated that cholesterol permeates into the CD cavities completely. Replicas consideration indicated that while the binding to 2HPβCD occurred perpendicularly and solely through positioning cholesterol's oxygen toward the primary hydroxyl rim (PHR), the mechanism of cholesterol binding to βCD and MβCD could take place with the orientation of oxygen towards both rims. Functionalization resulted in decreased cavity polarity, increased constriction tendency, and altered solubility and configuration of the carrier. Upon cholesterol binding, the CDs expanded, increasing the cavity volume in cholesterol-containing systems. The effects of cholesterol on the relative shape anisotropy (κ2) and asphericity parameter (b) in cyclodextrins were investigated. βCD exhibited a spherical structure regardless of cholesterol presence, while 2HPβCD and MβCD displayed more pronounced non-sphericity in the absence of cholesterol. Loading cholesterol transformed 2HPβCD and MβCD into more spherical shapes, with increased probabilities of higher κ2. MβCD showed a higher maximum peak of κ2 compared to 2HPβCD after cholesterol loading, while 2HPβCD maintained a significant maximum peak at 0.2 for b.

Selective Removal of 7KC by a Novel Atherosclerosis Therapeutic Candidate Reverts Foam Cells to a Macrophage-like Phenotype

The removal of the toxic oxidized cholesterol, 7-ketocholesterol (7KC), from cells through the administration of therapeutics has the potential to treat atherosclerosis and various other pathologies. While cholesterol is a necessary building block for homeostasis, oxidation of cholesterol can lead to the formation of toxic oxysterols involved in various pathologies, the most prominent of which is 7KC, which is formed through the non-enzymatic oxidation of cholesterol. Oxidized LDL (oxLDL) particles, highly implicated in heart disease, contain high levels of 7KC, and molecular 7KC is implicated in the pathogenesis of numerous diseases, including multiple sclerosis, hypercholesterolemia, sickle cell anemia, and multiple age related diseases. Of particular interest is the role of 7KC in the progression of atherosclerosis, with several studies associating elevated levels of 7KC with the etiology of the disease or in the transition of macrophages to foam cells. This research aims to elucidate the molecular mechanisms of UDP-003, a novel therapeutic, in mitigating the harmful effects of 7KC in mouse and human monocyte and macrophage cell lines. Experimental evidence demonstrates that administration of UDP-003 can reverse the foam cell phenotype, rejuvenating these cells by returning phagocytic function and decreasing both reactive oxygen species (ROS) and intracellular lipid droplet accumulation. Furthermore, our data suggests that the targeted removal of 7KC from foam cells with UDP-003 can potentially prevent and reverse atherosclerotic plaque formation. UDP-003 has the potential to be the first disease-modifying therapeutic approach to treating atherosclerotic disease.

Target and Cell Therapy for Atherosclerosis and CVD

Cardiovascular diseases (CVD) and, in particular, atherosclerosis, remain the main cause of death in the world today. Unfortunately, in most cases, CVD therapy begins after the onset of clinical symptoms and is aimed at eliminating them. In this regard, early pathogenetic therapy for CVD remains an urgent problem in modern science and healthcare. Cell therapy, aimed at eliminating tissue damage underlying the pathogenesis of some pathologies, including CVD, by replacing it with various cells, is of the greatest interest. Currently, cell therapy is the most actively developed and potentially the most effective treatment strategy for CVD associated with atherosclerosis. However, this type of therapy has some limitations. In this review, we have tried to summarize the main targets of cell therapy for CVD and atherosclerosis in particular based on the analysis using the PubMed and Scopus databases up to May 2023.

Monocyte and macrophage foam cells in diabetes-accelerated atherosclerosis

Diabetes results in an increased risk of atherosclerotic cardiovascular disease. This minireview will discuss whether monocyte and macrophage lipid loading contribute to this increased risk, as monocytes and macrophages are critically involved in the progression of atherosclerosis. Both uptake and efflux pathways have been described as being altered by diabetes or conditions associated with diabetes, which may contribute to the increased accumulation of lipids seen in macrophages in diabetes. More recently, monocytes have also been described as lipid-laden in response to elevated lipids, including triglyceride-rich lipoproteins, the class of lipids often elevated in the setting of diabetes.