Foam Cell Formation Research Articles

Evolving concepts in the pathophysiology of atherosclerosis: from endothelial dysfunction to thrombus formation through multiple shades of inflammation

Atherosclerosis is the anatomo-pathological substrate of most cardio, cerebro and vascular diseases such as acute and chronic coronary syndromes, stroke and peripheral artery diseases. The pathophysiology of atherosclerotic plaque and its complications are under continuous investigation. In the last 2 decades our understanding on the formation, progression and complication of the atherosclerotic lesion has greatly improved and the role of immunity and inflammation is now well documented and accepted. The conventional risk factors modulate endothelial function determining the switch to a proatherosclerotic phenotype. From this point, lipid accumulation with an imbalance from cholesterol influx and efflux, foam cells formation, T-cell activation, cytokines release and matrix-degrading enzymes production occur. Lesions with high inflammatory rate become vulnerable and prone to rupture. Once complicated, the intraplaque thrombogenic material, such as the tissue factor, is exposed to the flowing blood, thus inducing coagulation cascade activation, platelets aggregation and finally intravascular thrombus formation that leads to clinical manifestations of this disease. Nonconventional risk factors, such as gut microbiome, are emerging novel markers of atherosclerosis. Several data indicate that gut microbiota may play a causative role in formation, progression and complication of atherosclerotic lesions. The gut dysbiosis-related inflammation and gut microbiota-derived metabolites have been proposed as the main working hypothesis in contributing to disease formation and progression. The current evidence suggest that the conventional and nonconventional risk factors may modulate the degree of inflammation of the atherosclerotic lesion, thus influencing its final fate. Based on this hypothesis, targeting inflammation seems to be a promising approach to further improve our management of atherosclerotic-related diseases.

Abstract 466: CD36 Mediates Mitochondrial Reactive Oxygen Species Production Through PKM2 In Macrophages

Introduction: Excessive mitochondria-derived reactive oxygen species (mtROS) are associated with foam cell formation and atherosclerosis progression in both animal models and human patients. We previously showed that oxLDL/CD36 signaling stimulated mtROS production and facilitated diet-induced atherosclerosis in mice. However, underlying mechanisms by which oxLDL/CD36 pathway mediates mtROS production during atherosclerosis remain elusive. Pyruvate kinase M2 (PKM2) is a glycolytic enzyme recently discovered to facilitate foam cell and atherosclerosis development. We hypothesize that oxLDL/CD36 signaling mediates mtROS production by stimulating PKM2 mitochondrial translocation. Methods and Results: We separated mitochondria and cytosol fractions in murine peritoneal macrophages. OxLDL treatment upregulated PKM2 protein level in mitochondria fractions in a time-dependent manner (peak at 3h, ~2.5 fold), but not in cytosol. Confocal imaging further confirmed a translocation of PKM2 to mitochondria induced by oxLDL. This phenomenon was not observed in CD36-deficient macrophages. To investigate the mechanism, we immunoprecipitated PKM2 followed by mass spectrometry analysis of proteins associated with PKM2. GRP75, a known chaperone protein that imports cytosol proteins to the mitochondria was identified. Co-IP assay confirmed the interaction between GRP75 and PKM2, which was augmented by oxLDL (~3 fold). Moreover, UQCRC1, a subunit of mitochondrial electron transport chain (ETC) complex III, a major site of mtROS production, was also identified from mass spectrometry. Increased interaction between PKM2 and UQCRC1 induced by oxLDL (~3 fold) was further validated by coIP and in situ proximity ligation assay, which was dependent on CD36.In addition, PKM2 inhibitor Shikonin and PKM2 siRNA both inhibited the oxLDL-induced mtROS generation (by 50% and 100% respectively) in murine macrophages and human monocytes-derived macrophages. Conclusions: OxLDL/CD36 axis promotes PKM2 translocation to mitochondrial which facilitates mtROS production in macrophages. It highlights the novel role of PKM2 in mtROS production during atherosclerosis and implicates GRP75-PKM2-UQCRC1 axis as a potential therapeutic target.

Abstract 710: Specific Removal Of Oxidized Cholesterol With A Cyclodextrin Dimer Drug Candidate Towards Reversing Atherosclerosis

Cardiovascular disease (CVD) is the world’s biggest killer. Current treatments for CVD are failing to deliver on promises to beat this deadly and complex family of diseases. New approaches that go beyond targeting LDL are needed. Cyclarity Therapeutics has developed a novel class of specifically engineered, dimerized cyclodextrin (CD) molecules for the encapsulation of toxic oxidized cholesterol. Oxidized cholesterol accumulates over time and causes dysfunction in many cell types, linking it to several age-related diseases including atherosclerosis. Presently, treatments for atherosclerosis are invasive, expensive, and/or show limited benefits. Here, a combination of in silico, in vitro, and ex vivo methods are used to implement a synergistic rational drug design strategy for developing CDs to remove atherogenic oxidized cholesterol (primarily 7-ketocholesterol (7KC)) from cells and tissues. Our results thus far indicate that our lead compound, UDP-003, can both prevent and reverse the formation of atherogenic foam cells in-vitro. UDP-003 binds and clears 7KC from in-vivo and ex-vivo systems selectivity. IND enabling studies, including pivotal GLP studies in rodent and non-rodent species, are complete and show that UDP-003 has an excellent safety profile with no significant clinical liabilities. UDP-003 has been awarded the Innovative Licensing and Access Pathway (ILAP) Innovation Passport by the MHRA, which is accelerating Cyclarity’s path to clinic and will facilitate rapid and innovative clinical trials. In totality, our data suggest that targeted removal of 7KC from foam cells with our proprietary class of cyclodextrin compounds has the potential to prevent and reverse the formation of atherosclerotic plaques. This innovation represents the first disease-modifying therapeutic approach to treating atherosclerotic disease.

Abstract 229: Endothelial Cell Handling Of Atherogenic ApoB-carrying Lipoproteins

Atherosclerosis is triggered by the subendothelial retention of cholesterol-rich, apoB -containing LDL (which carries apoB100) and chylomicron remnants (which carry apoB48, the 48% N terminal sequence of apoB). In addition, multiple studies have established elevated postprandial TRLs as an independent risk factor for CVD. However, the mechanisms whereby postprandial TRLs (which circulate mostly within chylomicrons) exert their atherogenic effects remain unknown. Two receptors - SR-BI and ALK1 - have been shown to bind apoB and mediate transcytosis of LDL across the endothelium. We have shown that SR-BI also mediates EC uptake of nascent chylomicrons. RNAseq analysis revealed that ECs exposed to chylomicrons express a host of inflammatory and immune response genes, which does not occur with knockdown of SR-BI. In addition, following chylomicron uptake ECs release small extracellular vesicles that induce lipid accumulation in macrophages and lead to reduced eNOS phosphorylation in naïve ECs. Conversely, although binding of ALK1 to apoB is believed to occur through the N-terminus of apoB, the receptor is not involved in chylomicron uptake. Using a series of N terminal apoB peptides (apoB8-18, with sequences comprising the 8-18% N terminus of apoB), we found that chylomicron uptake was inhibited by apoB15 and apoB18, and LDL uptake was additionally inhibited by apoB12. These observations suggest that a) the binding sequence to SR-BI is between residues 547-684 of apoB, and b) an additional sequence between residues 365-547 participates in the binding to ALK1. Molecular modeling of apoB interactions identified an additional sequence in the C terminus of apoB potentially involved in the binding to ALK1. This sequence is absent in chylomicrons, which may explain why ALK1 inhibition and competition with apoB12 fail to significantly inhibit chylomicron uptake. Consistently, uptake of apoB100-carrying chylomicrons from Apobec -/- mice was inhibited by both ALK1 siRNA and competition with apoB12. Our observations suggest that a) the N terminus of apoB harbors distinct binding sequences to SR-BI and ALK1, and b) chylomicron uptake by ECs contributes to atherogenesis by inducing endothelial dysfunction, inflammation, and macrophage foam cell formation.

Abstract 716: Elabela Ameliorates Atherogenesis Through Restoring The M1/M2 Macrophage Balance In Apoe -/- Mice

Atherosclerosis is the leading cause of death in patients with cardiovascular disease worldwide. ELABELA, an early endogenous ligand for the G protein-coupled receptor APJ (apelin peptide jejunum, apelin receptor), maybe a novel therapeutic target for multiple cardiovascular diseases. The major goal of the present study was to test the potential therapeutic action of ELABELA in atherogenesis and the underlying mechanisms. ELABELA-21 (ELA-21) was used to treat low-density lipoprotein (ox-LDL)-incubated macrophages to detect macrophage foaminess. ApoE -/- mice were fed a high-fat diet (HFD) for 16 weeks and received subcutaneous injections of ELA-21 peptides (1 mg/kg/day) in the last 4 weeks to detect atherosclerotic plaque area, macrophage infiltration, and the balance between M1 and M2 macrophages. ELA-21 significantly ameliorated atherosclerosis in HFD-fed ApoE -/- mice, as characterized by significantly decreased atherosclerotic plaque area (40%, assessed by Oil-red-O staining), inhibited macrophage infiltration (45%, assessed by CD68 staining), and increased collagen content (65%, assessed by α-SMA staining). By RT-qPCR, ELA-21 treatment inhibited the mRNA expression of Icam-1 (49%), iNOS (53%), IL-1β (59%), IL-6 (55%), and Mc p-1 (80%) in the aorta of HFD-fed ApoE -/- mice. In vitro , ELA-21 treatment inhibited macrophage-derived foam cell formation (75.5%) induced by ox-LDL assessed by Oil-red-O staining. Additionally, in macrophages from the abdominal cavity of HFD-fed ApoE -/- mice, ELA-21 treatment abolished the lipid accumulation (50%) assessed by Oil-red-O staining, and modulated the balance between M1 and M2 macrophages toward a more anti-inflammatory status in HFD-fed ApoE -/- mice, as characterized by the significantly decreased mRNA levels of IL-1β (94%), Tnf-α (55%), iNOS (99%), and IL-12β (99%) (the markers of M1 macrophages), and elevated mRNA expression of Fizz1 (17777%), IL-10 (529%), and Cd206 (24%)(the markers of M2 macrophages). Collectively, our data highlighted an anti-atherosclerotic effect of ELA-21 by restoring the M1/M2 macrophage balance.

Homeobox A9 is a novel mediator of vascular smooth muscle cell phenotypic switching and proliferation by regulating methyl-CpG binding protein 2

Aberrant proliferation and phenotypic switching of vascular smooth muscle cells (VSMCs) are considered to be the main pathological processes of atherosclerotic plaque formation. Methyl-CpG binding protein 2 (MECP2) affects cell differentiation via modulating VSMC-specific gene expression and acts as a driver for the development of atherosclerosis (AS). Here, we aimed to elucidate the role of homeobox A9 (HOXA9) on aberrant VSMCs upon injury or AS, and whether HOXA9-mediated VSMC injury was associated with MECP2. Adeno-associated virus serotype 8-mediated knockdown of HOXA9 rescued aortic pathological injury of apolipoprotein E-deficient (ApoE−/−) mice fed a high-fat diet (HFD), characterized by the reduction of lipid accumulation and foam cell formation. Further in vitro evidence suggested that proliferation and migration of primary mouse VSMCs (mVSMCs) stimulated by oxidized low-density lipoprotein (ox-LDL) were inhibited after HOXA9 silencing. In addition, HOXA9 silencing blocked VSMC phenotypic switching from contractile to a pathological synthetic state. HOXA9 overexpression caused opposite alterations in ox-LDL-stimulated mVSMCs. Mechanistically, MECP2 was transcriptionally activated by HOXA9. Forced expression of MECP2 impaired the anti-proliferation, anti-migration, and phenotypic switching abilities of HOXA9 silencing in VSMCs upon ox-LDL stimulation. Collectively, our findings reveal that the role of HOXA9 in pathological vascular remodeling may attribute to transcriptional regulation of MECP2.

Sulforaphane Inhibits Foam Cell Formation and Atherosclerosis via Mechanisms Involving the Modulation of Macrophage Cholesterol Transport and the Related Phenotype

Sulforaphane (SFN), an isothiocyanate, is one of the major dietary phytochemicals found in cruciferous vegetables. Many studies suggest that SFN can protect against cancer and cardiometabolic diseases. Despite the proposed systemic and local vascular protective mechanisms, SFN’s potential to inhibit atherogenesis by targeting macrophages remains unknown. In this study, in high fat diet fed ApoE-deficient (ApoE−/−) mice, oral SFN treatment improved dyslipidemia and inhibited atherosclerotic plaque formation and the unstable phenotype, as demonstrated by reductions in the lesion areas in both the aortic sinus and whole aorta, percentages of necrotic cores, vascular macrophage infiltration and reactive oxygen species (ROS) generation. In THP-1-derived macrophages, preadministration SFN alleviated oxidized low-density lipoprotein (ox-LDL)-induced lipid accumulation, oxidative stress and mitochondrial injury. Moreover, a functional study revealed that peritoneal macrophages isolated from SFN-treated mice exhibited attenuated cholesterol influx and enhanced apolipoprotein A-I (apoA-I)- and high-density lipoprotein (HDL)-mediated cholesterol efflux. Mechanistic analysis revealed that SFN supplementation induced both intralesional and intraperitoneal macrophage phenotypic switching toward high expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and ATP-binding cassette subfamily A/G member 1 (ABCA1/G1) and low expression of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36), which was further validated by the aortic protein expression. These results suggest that the regulation of macrophages’ cholesterol transport and accumulation may be mainly responsible for SFN’s potential atheroprotective properties, and the regulatory mechanisms might involve upregulating ABCA1/G1 and downregulating CD36 via the modulation of PPARγ and Nrf2.

Targeting foam cell formation to improve recovery from ischemic stroke

Inflammation is a crucial part of the healing process after an ischemic stroke and is required to restore tissue homeostasis. However, the inflammatory response to stroke also worsens neurodegeneration and creates a tissue environment that is unfavorable to regeneration for several months, thereby postponing recovery. In animal models, inflammation can also contribute to the development of delayed cognitive deficits. Myeloid cells that take on a foamy appearance are one of the most prominent immune cell types within chronic stroke infarcts. Emerging evidence indicates that they form as a result of mechanisms of myelin lipid clearance becoming overwhelmed, and that they are a key driver of the chronic inflammatory response to stroke. Therefore, targeting lipid accumulation in foam cells may be a promising strategy for improving recovery. The aim of this review is to provide an overview of current knowledge regarding inflammation and foam cell formation in the brain in the weeks and months following ischemic stroke and identify targets that may be amenable to therapeutic intervention.

The cell origins of foam cell and lipid metabolism regulated by mechanical stress in atherosclerosis.

Atherosclerosis is an inflammatory disease initiated by endothelial activation, in which lipoprotein, cholesterol, extracellular matrix, and various types of immune and non-immune cells are accumulated and formed into plaques on the arterial wall suffering from disturbed flow, characterized by low and oscillating shear stress. Foam cells are a major cellular component in atherosclerotic plaques, which play an indispensable role in the occurrence, development and rupture of atherosclerotic plaques. It was previously believed that foam cells were derived from macrophages or smooth muscle cells, but recent studies have suggested that there are other sources of foam cells. Many studies have found that the distribution of atherosclerotic plaques is not random but distributed at the bend and bifurcation of the arterial tree. The development and rupture of atherosclerotic plaque are affected by mechanical stress. In this review, we reviewed the advances in foam cell formation in atherosclerosis and the regulation of atherosclerotic plaque and lipid metabolism by mechanical forces. These findings provide new clues for investigating the mechanisms of atherosclerotic plaque formation and progression.

Integrative analysis of HASMCs gene expression profile revealed the role of thrombin in the pathogenesis of atherosclerosis

We explored the effect of thrombin on human aortic smooth muscle cells (HASMCs) and further analyzed its role in the pathogenesis of atherosclerosis (AS). Thrombin-induced differentially expressed genes (DEGs) in HASMCs were identified by analyzing expression profiles from the GEO. Subsequently, enrichment analysis, GSEA, PPI network, and gene-microRNAs networks were interrogated to identify hub genes and associated pathways. Enrichment analysis results indicated that thrombin causes HASMCs to secrete various pro-inflammatory cytokines and chemokines, exacerbating local inflammatory response in AS. Moreover, we identified 9 HUB genes in the PPI network, which are closely related to the inflammatory response and the promotion of the cell cycle. Additionally, we found that thrombin inhibits lipid metabolism and autophagy of HASMCs, potentially contributing to smooth muscle-derived foam cell formation. Our study deepens a mechanistic understanding of the effect of thrombin on HASMCs and provides new insight into treating AS.

Activation of the High Mobility Group Box 1/Receptor for Advanced Glycation Endproducts /NOD-like Receptor Family Pyrin Domain-Containing 3 Axis Under Chronic Intermittent Hypoxia Induction Promotes the Progression of Atherosclerosis in ApoE-/- Mice.

Background Chronic intermittent hypoxia (CIH) has been regarded as an important cause of atherosclerotic disease. In our study, we set out to investigate whether CIH regulated the high mobility group box 1/receptor for advanced glycation endproducts/NOD-like receptor family pyrin domain-containing 3 (HMGB1/RAGE/NLRP3) axis to affect the progression of atherosclerosis. Methods and Results Initially, peripheral blood samples were collected from patients with single obstructive sleep apnea, atherosclerosis complicated with obstructive sleep apnea, and healthy volunteers. In vitro cell experiments were conducted using human monocyte cell line THP-1 and human umbilical vein endothelial cells to explore the role of HMGB1 in cell migration, apoptosis, adhesion, and transendothelial migration. In addition, a CIH-induced atherosclerosis mouse model was established for further identifying the critical role of the HMGB1/RAGE/NLRP3 axis in atherosclerosis. Upregulated HMGB1 and RAGE were found in patients with atherosclerosis complicated with obstructive sleep apnea. CIH induction increased HMGB1 expression by inhibiting HMGB1 methylation, activating the RAGE/NLRP3 axis. After inhibition of the HMGB1/RAGE/NLRP3 axis, monocyte chemotaxis and adhesion were repressed, and macrophage-derived foam cell formation was inhibited, accompanied by suppression of endothelial and foam cell apoptosis and inflammatory factor secretion. In vivo animal experiments also noted that the progression of atherosclerosis was prevented by inhibition of the HMGB1/RAGE/NLRP3 axis in CIH-induced ApoE-/- mice. Conclusions Taken together, CIH induction can upregulate HMGB1 through inhibition of HMGB1 methylation, which activates the RAGE/NLRP3 axis to promote inflammatory factor secretion, thereby promoting the progression of atherosclerosis.

PCSK9 inhibitor attenuates atherosclerosis by regulating SNHG16/EZH2/TRAF5-mediated VSMC proliferation, migration, and foam cell formation.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor has been demonstrated to exert a great cardioprotection in cardiometabolic impairments, including atherosclerosis. However, its underlying mechanism remains not fully understood. This study focuses on uncovering the actions of PCSK9 inhibitor on the connection between atherosclerosis and vascular smooth muscle cell (VSMC) behaviors. qRT-PCR was utilized to detect the expression of SNHG16. Proliferation and migration of VSMC were characterized by Cell Counting Kit-8 and wound healing assays. The intracellular lipids and foam cell formation were assessed by Oil Red O staining, fluorescence image, and cholesterol quantification kit. Atherosclerosis in vivo was evaluated by imaging the atherosclerotic lesions, hematoxylin-eosin staining, Oil Red O staining and Masson staining. The interaction between SNHG16 with EZH2 and histone H3 lysine 27 trimethylation (H3K27me3) were investigated by fluorescence in situ hybridization, RNA immunoprecipitation, and chromatin immunoprecipitation assays. A ApoE-/- mice model was used to validate the role of PCSK9 inhibitor and SNHG16 for atherosclerosis. The protective regulation of PCSK9 inhibitor was observed both in high-fat diet (HFD)-fed mice and oxidized low-density lipoprotein (ox-LDL)-treated VSMC, as manifested in the decreased the atherosclerotic lesions in vivo, as well as the weakened cell proliferation, migration, and formation of foam cells in vitro. SNHG16 was identified to be a downstream effector of PCSK9 inhibitor-mediated biological functions, of which knockdown also significantly ox-LDL-treated VSMC proliferation, migration, and foam cell formation abilities. SNHG16 epigenetically suppressed TRAF5 via recruiting EZH2. Silencing of TRAF5 abolished the protective effects of SNHG16 knockdown on the pathogenesis of atherosclerosis. Collectively, PCSK9 inhibitor attenuated atherosclerosis by regulating SNHG16/EZH2/TRAF5 axis to impair the proliferation, migration, and foam cell formation of VSMC.

Assessment of Analgesic Efficacy of Ziziphus jujube Hydroalcholic Fruit Extract

Pain is a term that refers to a spectrum of sensations of varying types and intensities, ranging from unpleasant to intolerable. The struggle to relieve pain began with the advent of mankind. Analgesics can be defined as drugs that reduce the sensation of pain without losing consciousness. Analgesics act in different ways on the peripheral and central nervous systems. They differ from anesthetics in that they reversibly eliminate sensation, acetaminophen [known in the US as acetaminophen, or simply APAP], non-steroidal anti-inflammatory drugs [NSAIDs] such as salicylates, morphine and opioids such as opiates. When choosing an analgesic, the severity and response to other drugs determine drug choice. World Health Organization [WHO] pain ladder. Herbal medicines have less side effects and less harm, so they have a higher market value. The nutritious jujube fruit (Ziziphus jujube Mill.) is a member of the Rhamnaceous family and grows mainly in inland areas of Europe, southern and eastern Asia, Australia and especially northern China. Jujubes have a long history as fruit and medicinal. The main bioactive components are vitamin C, phenols, flavonoids, triterpenoids and polysaccharides. Recent phytochemical studies of jujube fruit have highlighted the following biological effects: B. Anticancer, anti-inflammatory, anti-obesity, immunostimulatory, antioxidant, hepatoprotective and gastrointestinal protective activity in macrophages and inhibition of foam cell formation. Further focus on clinical trials and phytochemical definitions of jujube fruit will be essential for future research efforts. In this study, an attempt was made to evaluate the analgesic potential of Ziziphus jujube hydroalcoholic fruit extract.

TCTAP A-072 Potential Genes and Pathways Related to the Foam Cell Formation Identified via Microarray Gene Expression Dataset Re-Analysis

TCTAP A-072 Potential Genes and Pathways Related to the Foam Cell Formation Identified via Microarray Gene Expression Dataset Re-Analysis

Schisanhenol ameliorates oxLDL-caused endothelial dysfunction by inhibiting LOX-1 signaling.

Atherosclerotic lesions play a critical role in leading cardiovascular diseases. Oxidized low-density lipoprotein (OxLDL) is a vital risk factor for atherosclerosis since it acts a crucial role in endothelial dysfunction and foam cell formation. Schisanhenol, a composition extracted from the fruit of Schisandra rubriflora, has been reported to have antioxidative effects on human LDL oxidation. This study investigates whether Schisanhenol protects against oxLDL-mediated endothelial damage by modulating the lectin-like oxLDL receptor-1 (LOX-1)-mediated inflammatory processes. Human umbilical vein endothelial cells (HUVECs) were pre-treated with 10 or 20 μM Schisanhenol for 2 h and then exposed to 150 μg/mL oxLDL. We revealed that Schisanhenol reduced oxLDL-enhanced LOX-1 expression. We also found that oxLDL down-regulated endothelial nitric oxide synthase (eNOS) as well as activated inducible NOS (iNOS), thereby enhancing the generation of nitric oxide (NO). Moreover, oxLDL elevated the expression levels of phosphorylated-p38MAPK, subsequently promoting NF-κB-modulated inflammatory responses. Pretreatment with Schisanhenol exerted significant cytoprotective function in all the above-mentioned detrimental events. Results from this present study reveal that Schisanhenol has a potential therapeutic effect on preventing oxLDL-induced endothelial injuries.

Attenuating lipid metabolism in atherosclerosis: The potential role of Anti-oxidative effects on low-density lipoprotein of herbal medicines.

Atherosclerosis (AS) is a multifactorial chronic disease with great harm to the health of human being, which is a basic pathogenesis of many cardiovascular diseases and ultimately threatens human life. Abnormal blood lipid level is one of the most common diagnostic indicators of AS in clinic, and lipid metabolism disorder is often observed in patients with AS. Cholesterol is an important lipid in the human body, which is of great significance for maintaining normal life activities. Generally, cholesterol is transported to peripheral tissues by low-density lipoprotein (LDL), and then transported to the liver by high-density lipoprotein (HDL) via its cholesterol reverse transport function, and finally discharged. Under oxidative stress condition, LDL is commonly oxidized to the form ox-LDL, which is ingested by macrophages in large quantities and further forms foam cells, disrupting the normal metabolic process of cholesterol. Importantly, the foam cells are involved in forming atherosclerotic plaques, whose rupture may lead to ischemic heart disease or stroke. Furthermore, ox-LDL could also promote the development of AS by damaging vascular endothelium, promoting the migration and proliferation of smooth muscle cells, and activating platelets. Therefore, inhibiting LDL oxidation may be an effective way to improve lipid metabolism and prevent AS. In recent years, increasing studies have shown that herbal medicines have great potentiality in inhibiting LDL oxidation and reducing ox-LDL induced foam cell formation. Accordingly, this paper summarized current research on the inhibitory effects of herbal medicines against LDL oxidation and foam cell formation, and made a brief description of the role of cholesterol and LDL in lipid metabolism disorder and AS pathogenesis. Importantly, it is suggested that herbal medicines could inhibit LDL oxidation and regulate cholesterol homeostasis via downregulation of CD36 and SR-A, whereas upregulation of ABCA1 and ABCG1.

SMTP-44D Inhibits Atherosclerotic Plaque Formation in Apolipoprotein-E Null Mice Partly by Suppressing the AGEs-RAGE Axis

SMTP-44D has been reported to have anti-oxidative and anti-inflammatory reactions, including reduced expression of receptor for advanced glycation end products (RAGE) in experimental diabetic neuropathy. Although activation of RAGE with its ligands, and advanced glycation end products (AGEs), play a crucial role in atherosclerotic cardiovascular disease, a leading cause of death in diabetic patients, it remains unclear whether SMTP-44D could inhibit experimental atherosclerosis by suppressing the AGEs-RAGE axis. In this study, we investigated the effects of SMTP-44D on atherosclerotic plaque formation and expression of AGEs in apolipoprotein-E null (Apoe-/-) mice. We further studied here whether and how SMTP-44D inhibited foam cell formation of macrophages isolated from Apoe-/- mice ex vivo. Although administration of SMTP-44D to Apoe-/- mice did not affect clinical or biochemical parameters, it significantly decreased the surface area of atherosclerotic lesions and reduced the atheromatous plaque size, macrophage infiltration, and AGEs accumulation in the aortic roots. SMTP-44D bound to immobilized RAGE and subsequently attenuated the interaction of AGEs with RAGE in vitro. Furthermore, foam cell formation evaluated by Dil-oxidized low-density lipoprotein (ox-LDL) uptake, and gene expression of RAGE, cyclin-dependent kinase 5 (Cdk5) and CD36 in macrophages isolated from SMTP-44D-treated Apoe-/- mice were significantly decreased compared with those from saline-treated mice. Gene expression levels of RAGE and Cdk5 were highly correlated with each other, the latter of which was also positively associated with that of CD36. The present study suggests that SMTP-44D may inhibit atherosclerotic plaque formation in Apoe-/- mice partly by blocking the AGEs-RAGE-induced ox-LDL uptake into macrophages via the suppression of Cdk5-CD36 pathway.

A two-pronged detection of atherosclerosis with a dual-channel fluorescent probe for viscosity and hypochlorous acid

The precise detection of atherosclerosis has been a research hot point since its importance in the diagnosis of cardiovascular diseases. Here we synthesized a near-infrared fluorescent probe AS-CN with a D − π − A structure, enabling independent dual-response determination of hypochlorous acid (HOCl) and viscosity during AS progression. The performance of this probe is excellent, with large Stokes shift, low detection limit, high sensitivity, and good biocompatibility. The simultaneous variations of HOCl and viscosity during the formation of foam cells were successfully investigated for the first time. Especially, we further applied it to achieve the non-invasive in vivo detection in the atherosclerotic mouse and realized the evaluation of atherosclerosis from chemical (ROS) and physical (viscosity) dimensions, respectively. We hope that AS-CN acts as a potent tool in the detection of atherosclerosis.

Impact of Impaired Cholesterol Homeostasis on Neutrophils in Atherosclerosis.

Atherosclerosis is complex chronic disease characterized by intimal cholesterol accumulation and vascular inflammation. There is a well-established relationship of hypercholesterolemia and inflammation with atherosclerosis. However, the link between inflammation and cholesterol is not completely understood. Myeloid cells, in particular, monocytes, macrophages, and neutrophils play essential roles in the pathogenesis of atherosclerotic cardiovascular disease. It is well known that macrophages accumulate cholesterol, forming foam cells, which drive atherosclerosis-associated inflammation. However, the interaction between cholesterol and neutrophils remains poorly defined-an important gap in the literature given that neutrophils represent up to 70% of total circulating leukocytes in humans. Elevated levels of biomarkers of neutrophil activation (myeloperoxidase and neutrophil extracellular traps) and higher absolute neutrophil counts are both associated with increased rates of cardiovascular events. Neutrophils contain the necessary machinery to uptake, synthesize, efflux and esterify cholesterol; yet, the functional consequence of dysregulated cholesterol homeostasis on neutrophil activity remains poorly defined. Preclinical animal data suggest a direct link between cholesterol metabolism and hematopoiesis, although current evidence in humans has been unable to corroborate such findings. This review will explore the impact of impaired cholesterol homeostasis neutrophils and draw focus on the discordant data from animal models and atherosclerotic disease in humans.

Autophagy inhibition and ferroptosis activation during atherosclerosis: Hypoxia-inducible factor 1α inhibitor PX-478 alleviates atherosclerosis by inducing autophagy and suppressing ferroptosis in macrophages

ObjectiveTo elucidate the key regulator responsible for autophagy and ferroptosis, and if specific pharmacological inhibitor of upregulated gene exerted the pro-autophagic and anti-ferroptotic effect on macrophage to alleviate the atherosclerosis. MethodsAutophagy and ferroptosis were evaluated in atherosclerotic lesions and THP-1 macrophages exposed to ox-LDL. Autophagy/ferroptosis-related differentially expressed genes (DEGs) in atherosclerosis were identified by bioinformatic analysis of GSE97210 dataset, and were validated in atherosclerotic cells and tissues. The efficacy and mechanism of pharmacological inhibition of the validated DEGs on alleviating atherosclerosis were explored in vivo and in vitro. ResultsAtherosclerotic lesions were characterized by autophagy inhibition and ferroptosis activation in macrophages. The crosslink between autophagy and ferroptosis were demonstrated. Ox-LDL induced THP-1 macrophage foam cell formation, autophagy dysfunction, and ferroptosis occurrence. Rapamycin ameliorated and, conversely, erastin deteriorated the effect of ox-LDL on THP-1 macrophages. Eleven autophagy/ferroptosis-related DEGs were identified in atherosclerosis vs. normal. The up-regulated expression of HIF-1α was verified in atherosclerotic lesions and THP-1 macrophages induced by ox-LDL. HIF-1α inhibitor PX-478 restored autophagy function, depressed ferroptosis, and reduced lipid accumulation in ox-LDL induced THP-1 macrophage. Autophagy inhibitor 3-MA obviously abrogated the pro-autophagic, anti-ferroptotic, and anti-atherosclerotic effects of PX-478. PX-478 treatment down-regulated HIF-1α expression and reduced atherosclerotic plaques in the mice model. ConclusionsAutophagy is inhibited, ferroptosis is activated, and crosslink occurs between autophagy and ferroptosis during atherosclerosis. HIF-1α, an upregulated DEG between atherosclerosis and normal, co-regulates autophagy and ferroptosis. HIF-1α inhibitor PX-478 attenuates foam cell formation and lessens atherosclerosis by enhancing autophagy and depressing ferroptosis in macrophages.