ApoA-I Infusions and Burden of Ischemic Events After Acute Myocardial Infarction: Insights From the AEGIS-II Trial.

BACKGROUND: Following an acute myocardial infarction (AMI), patients remain at risk for subsequent cardiovascular (CV) events. In the AEGIS-II trial, CSL112, a human apolipoprotein A-I derived from plasma that enhances cholesterol efflux, did not significantly reduce the first occurrence of CV death, myocardial infarction (MI), or stroke through 90 days compared with placebo. However, an analysis involving only the first event may not capture the totality of the clinical impact of an intervention because patients may experience multiple events. OBJECTIVES: This prespecified exploratory analysis examines the effect of CSL112 on total burden of nonfatal ischemic events (ie, recurrent MI and stroke) and CV death. METHODS: A total of 18,219 patients with AMI, multivessel coronary artery disease, and additional CV risk factors were randomized to either 4 weekly infusions of 6 g CSL112 (n = 9,112) or matching placebo (n = 9,107). A negative binomial regression model was applied to estimate the effect of CSL112 compared with placebo on the rate ratio (RR) of ischemic events. RESULTS: For CV death, MI, and stroke, there were numerically fewer total events at 90 days (503 vs 545 events; rate ratio [RR]: 0.88; 95% CI: 0.76-1.03, P = 0.11), and nominally significantly fewer total events at 180 days (745 vs 821 events, RR: 0.87; 95% CI: 0.77-0.99; P = 0.04) and 365 days (1,120 vs 1,211 events; RR 0.89; 95% CI: 0.80-0.99; P = 0.04). Subsequent events constituted 13% of events at 90 days, 17% at 180 days, and 22% at 1 year. Similar findings were seen with the total occurrence of nonfatal MI and CV death. When type II MIs, unlikely to be modified by enhancing cholesterol efflux, were excluded, there were nominally significant reductions in the total occurrence of nonfatal MI (excluding type 2) and CV death at all timepoints (90 days: RR: 0.81; 95% CI: 0.68-0.97; P = 0.02; 180 days: RR: 0.82; 95% CI: 0.71-0.95; P < 0.01; 365 days: RR: 0.86; 95% CI: 0.76-0.98; P = 0.02). CONCLUSIONS: In this prespecified exploratory analysis of the AEGIS-II trial, 4 weekly infusions of CSL112 among high-risk patients after AMI significantly reduced the total burden of nonfatal ischemic events and CV death at 180 and 365 days compared with placebo. (AEGIS-II [Study to Investigate CSL112 in Subjects With Acute Coronary Syndrome]; NCT03473223).

Apolipoprotein A-I Infusions and Cardiovascular Outcomes in Acute Myocardial Infarction According to Baseline LDL-Cholesterol Levels: The AEGIS-II Trial.

BACKGROUND AND AIMS: In the AEGIS-II trial (NCT03473223), CSL112, a human apolipoprotein A1 derived from plasma that increases cholesterol efflux capacity, did not significantly reduce the risk of the primary endpoint through 90 days versus placebo after acute myocardial infarction (MI). Nevertheless, given the well-established relationship between higher low-density lipoprotein cholesterol (LDL-C) and plaque burden, as well as greater risk reductions seen with PCSK9 inhibitors in patients with baseline LDL-C ≥100 mg/dL on statin therapy, the efficacy of CSL112 may be influenced by baseline LDL-C. METHODS: Overall, 18,219 patients with acute MI, multivessel coronary artery disease, and additional risk factors were randomized to either four weekly infusions of 6 g CSL112 or placebo. This exploratory post-hoc analysis evaluated cardiovascular outcomes by baseline LDL-C in patients prescribed guideline-directed statin therapy at the time of randomization (n=15,731). RESULTS: As baseline LDL-C increased, risk of the primary endpoint at 90 days lowered in those treated with CSL112 compared with placebo. In patients with LDL-C ≥100 mg/dL at randomization, there was a significant risk reduction of cardiovascular death, MI, or stroke in the CSL112 vs. placebo group at 90, 180, and 365 days (hazard ratio 0.69 [0.53-0.90], 0.71 [0.57-0.88], and 0.78 [0.65-0.93]). In contrast, there was no difference between treatment groups among those with LDL-C <100 mg/dL at baseline. CONCLUSIONS: In this population, treatment with CSL112 compared to placebo was associated with a significantly lower risk of recurrent cardiovascular events among patients with a baseline LDL-C ≥100 mg/dL. Further studies need to confirm that CSL112 efficacy is influenced by baseline LDL-C.

IFIT2 mediates iron retention and cholesterol efflux in atherosclerosis.

BACKGROUND: Abnormalities in iron and lipid metabolism are recognized as key contributors to atherosclerosis (AS). Therefore, this study proposes to characterize the biomarker related to iron and lipid metabolism in AS using bioinformatics, animal, and cell experiments. METHODS: The limma package was utilized to identify differentially expressed genes (DEGs) in GSE70126 and GSE70619 datasets, and biomarkers were screened using enrichment analysis and PPI networks. IFIT2 was knocked down using shRNA lentivirus in a high fat diet (HFD)-induced APOE-/- AS model to investigate its effects of IFIT2 on the pathology, iron retention, and lipid accumulation. Iron storage-related and cholesterol efflux-related proteins were evaluated following exogenous modulation of IFIT2 expression in ox-LDL-induced foamy macrophages. RESULTS: Compared to non-foamy macrophages from the aorta, 189 and 4152 DEGs were identified in foamy macrophages within the GSE70126 and GSE70619 datasets, respectively. Moreover, intersecting DEGs may modulate immune responses, cell adhesion, vascular permeability, and oxidative stress through NF-kappa B, Wnt, TNF and HIF-1 signaling pathways. Notably, IFIT2 was significantly upregulated in foamy macrophages and AS models. In vivo, IFIT2 co-localized with foamy macrophages, and its knockdown led to reductions in plasma lipid levels, plaque area, immune infiltration, iron retention, and lipid accumulation. In vitro, IFIT2 knockdown alleviated the ox-LDL-induced increase in iron storage-related proteins (Ferritin-L and Ferritin-H) and iron (Fe2+ and Fe3+) in foamy macrophages. Furthermore, IFIT2 knockdown reduced lipid accumulation and upregulated cholesterol efflux-related proteins (PPARγ, LXRα, ABCA1, and ABCG1) in foamy macrophages. CONCLUSION: IFIT2 knockdown attenuates iron retention and lipid accumulation in AS plaques, and facilitated cholesterol efflux from foamy macrophages via the PPARγ/LXRα/ABCA1-ABCG1 pathway.

Effects of dietary interventions and intermittent fasting on HDL function in obese individuals with T2DM: a randomized controlled trial.

BACKGROUND: Cardiovascular disease represents a significant risk factor for mortality in individuals with type 2 diabetes mellitus (T2DM). High-density lipoprotein (HDL) is believed to play a crucial role in maintaining cardiovascular health through its multifaceted atheroprotective effects and its capacity to enhance glycemic control. The impact of dietary interventions and intermittent fasting (IF) on HDL functionality remains uncertain. The objective of this study was to assess the effects of dietary interventions and IF as a strategy to safely improve glycemic control and reduce body weight on functional parameters of HDL in individuals with T2DM. METHODS: Before the 12-week intervention, all participants (n = 41) of the INTERFAST-2 study were standardized to a uniform basal insulin regimen and randomized to an IF or non-IF group. Additionally, all participants were advised to adhere to dietary recommendations that promoted healthy eating patterns. The IF group (n = 19) followed an alternate-day fasting routine, reducing their calorie intake by 75% on fasting days. The participants' glucose levels were continuously monitored. Other parameters were measured following the intervention: Lipoprotein composition and subclass distribution were measured by nuclear magnetic resonance spectroscopy. HDL cholesterol efflux capacity, paraoxonase 1 (PON1) activity, lecithin cholesterol acyltransferase (LCAT) activity, and cholesterol ester transfer protein (CETP) activity were assessed using cell-based assays and commercially available kits. Apolipoprotein M (apoM) levels were determined by ELISA. RESULTS: Following the 12-week intervention, the IF regimen significantly elevated serum apoM levels (p = 0.0144), whereas no increase was observed in the non-IF group (p = 0.9801). ApoM levels correlated with weight loss and fasting glucose levels in the IF group. Both groups exhibited a robust enhancement in HDL cholesterol efflux capacity (p < 0.0001, p = 0.0006) after 12 weeks. Notably, only the non-IF group exhibited significantly elevated activity of PON1 (p = 0.0455) and LCAT (p = 0.0117) following the 12-week intervention. In contrast, the changes observed in the IF group did not reach statistical significance. CONCLUSIONS: A balanced diet combined with meticulous insulin management improves multiple metrics of HDL function. While additional IF increases apoM levels, it does not further enhance other aspects of HDL functionality. TRIAL REGISTRATION: The study was registered at the German Clinical Trial Register (DRKS) on 3 September 2019 under the number DRKS00018070.

Short-term HIIT impacts HDL function differently in lean, obese, and diabetic subjects.

Introduction: High density lipoproteins (HDL) exert cardiovascular protection in part through their antioxidant capacity and cholesterol efflux function. Effects of exercise training on HDL function are yet to be well established, while impact on triacylglycerol (TG)-lowering has been often reported. We previously showed that a short-term high-intensity interval training (HIIT) program improves insulin sensitivity but does not inhibit inflammatory pathways in immune cells in insulin-resistant subjects. The purpose of this study is to evaluate HDL function along with changes of lipoproteins after the short-term HIIT program in lean, obese nondiabetic, and obese type 2 diabetic (T2DM) subjects. Methods: All individuals underwent a supervised 15-day program of alternative HIIT for 40 minutes per day. VO2peak was determined before and after this training program. A pre-training fasting blood sample was collected, and the post-training fasting blood sample collection was performed 36 hours after the last exercise session. Results: Blood lipid profile and HDL function were analyzed before and after the HIIT program. Along with improved blood lipid profiles in obese and T2DM subjects, the HIIT program affected circulating apolipoprotein amounts differently. The HIIT program increased HDL-cholesterol levels and improved the cholesterol efflux capacity only in lean subjects. Furthermore, the HIIT program improved the antioxidant capacity of HDL in all subjects. Data from multiple logistic regression analysis showed that changes in HDL antioxidant capacity were inversely associated with changes in atherogenic lipids and changes in HDL-TG content. Discussion: We show that a short-term HIIT program improves aspects of HDL function depending on metabolic contexts, which correlates with improvements in blood lipid profile. Our results demonstrate that TG content in HDL particles may play a negative role in the anti-atherogenic function of HDL.

Obstructive sleep apnea syndrome attenuated high-density lipoprotein function.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular disease. High-density lipoproteins (HDLs) exert anti-atherogenic effects, even on cholesterol efflux capacity (CEC). The HDL proteome is reportedly altered in patients with coronary artery disease. OBJECTIVE: We hypothesized that OSA attenuates HDL function through an altered HDL proteome, which could be alleviated by continuous positive airway pressure (CPAP) therapy. METHODS: Patients aged ≥20 years (n = 115) with suspected OSA were enrolled in this cross-sectional study, with 34 patients diagnosed with moderate and severe OSA included in the interventional study and treated with CPAP therapy for 12 weeks. To further investigate the HDL proteome in OSA, we conducted a discovery study by analyzing HDL proteomes in 10 patients. RESULTS: In this study, CEC was significantly lower in the sleep apnea syndrome (SAS) group (apnea-hypopnea index [AHI] ≥5) than in the non-SAS group (AHI <5; 0.96 ± 0.14 vs. 1.06 ± 0.15, p = 0.01). Multiple regression analysis revealed that minimal pulse oxygen saturation (MinSpO2) was positively correlated with CEC. In the interventional study, a 12-week CPAP therapy did not affect CEC. We identified orosomucoid 1 (ORM1), an acute-phase inflammatory molecule, as a candidate protein for OSA-induced HDL dysfunction. Further validation study revealed that serum ORM1 levels were inversely associated with CEC, independent of HDL-cholesterol and high-sensitivity C-reactive protein. CONCLUSIONS: HDL function was impaired in patients with OSA and a reduced CEC. However, CPAP therapy did not affect CEC. An altered HDL proteome, particularly with increased ORM1 levels, may be associated with impaired HDL function. TRIAL REGISTRATION: This clinical study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000025335 and UMIN000025341).

Impaired HDL antioxidant and anti-inflammatory functions are linked to increased mortality in acute heart failure patients.

AIMS: Acute heart failure (AHF) is typified by inflammatory and oxidative stress responses, which are associated with unfavorable patient outcomes. Given the anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL), this study sought to examine the relationship between impaired HDL function and mortality in AHF patients. The complex interplay between various HDL-related biomarkers and clinical outcomes remains poorly understood. METHODS: HDL subclass distribution was quantified by nuclear magnetic resonance spectroscopy. Lecithin-cholesterol acyltransferase (LCAT) activity, cholesterol ester transfer protein (CETP) activity, and paraoxonase (PON-1) activity were assessed using fluorometric assays. HDL-cholesterol efflux capacity (CEC) was assessed in a validated assay using [3H]-cholesterol-labeled J774 macrophages. RESULTS: Among the study participants, 74 (23.5 %) out of 315 died within three months after hospitalization due to AHF. These patients exhibited lower activities of the anti-oxidant enzymes PON1 and LCAT, impaired CEC, and lower concentration of small HDL subclasses, which remained significant after accounting for potential confounding factors. Smaller HDL particles, particularly HDL3 and HDL4, exhibited a strong association with CEC, PON1 activity, and LCAT activity. CONCLUSIONS: In patients with AHF, impaired HDL CEC, HDL antioxidant and anti-inflammatory function, and impaired HDL metabolism are associated with increased mortality. Assessment of HDL function and subclass distribution could provide valuable clinical information and help identify patients at high risk.

HDL regulates the risk of cardiometabolic and inflammatory-related diseases: Focusing on cholesterol efflux capacity.

Dyslipidemia, characterized by higher serum concentrations of low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), triglyceride (TG), and lower serum concentrations of high-density lipoprotein cholesterol (HDL-C), is confirmed as a hallmark of cardiovascular diseases (CVD), posing serious risks to the future health of humans. Aside from the role of HDL-C concentrations, the capacity of cholesterol efflux to HDL is being identified as an enssential messurement for the dyslipidemic morbidity. Through inducing the progression of reverse cholesterol transport (RCT), the HDL-related cholesterol efflux plays a vital role in atherosclerotic plaque formation. In addition, increasing results demonstrated that the relationships between cholesterol efflux and cardiovascular events might be influenced by multiple factors, such as atherosclerosis, diabetes, and, inflammatory diseases. These risk factors could affect the intracellular composition of HDL, which might subsqently influence the cholesterol efflux process induced by HDL particle. In the present comprehensive article, we summarize the latest findings which described the modulatory roles of HDL in cardiometabolic disorders and inflammatory related diseases, focusing on its capacity in mediating cholesterol efflux. Moreover, the potential mechanisms whereby HDL regulate the risk of cardiometabolic disorders or inflammatory related diseases, at least partly, via cholesterol efflux pathway, are also well-listed.

Communication: High-Density Lipoprotein-Specific Phospholipid Efflux in Familial Hypercholesterolemia.

OBJECTIVE: Familial hypercholesterolemia (FH) is characterized by elevated levels of low-density lipoprotein cholesterol (LDL-C) and cardiovascular disease (CVD). Although the role of LDL-C in FH has been studied, the contribution of high-density lipoproteins (HDL) to CVD in FH remains unknown. This study aimed at highlighting the role of HDL in FH. METHODS: HDL-specific phospholipid efflux (HDL-SPE) assay was developed to predict CVD risk. HDL-SPE was examined in FH patients (n=30) and compared with age- and sex-matched non-FH controls (n=60). RESULTS: FH patients had significantly lower HDL-SPE levels (0.90±0.12) than controls (1.12±0.10; p<0.05), despite similar HDL-cholesterol levels in both groups (FH: 57.9±18.7 mg/dl; controls: 57.1±13.8 mg/dl). These differences remained significant after adjusting for confounders. CONCLUSIONS: These findings suggest there may be dysfunctionality of HDL in FH.

Rice bran active peptide (RBAP) inhibited macrophage differentiation to foam cell and atherosclerosis in mice via regulating cholesterol efflux.

BACKGROUND: Atherosclerosis is a long-lasting inflammatory condition affecting the walls of arteries, marked by the buildup of fats, plaque formation, and vascular remodeling. Recent findings highlight the significance of cholesterol removal pathways in influencing atherosclerosis, yet the connection between cholesterol removal and regulation of macrophage inflammation remains poorly understood. RBAP could serve as an anti-inflammatory agent; however, its role in atherosclerosis and the mechanism behind it are still not well understood. PURPOSE: The objective of this research is to explore how RBAP impacts cholesterol efflux, which is a considerable element in the advancement of atherosclerosis. METHODS: An atherosclerosis mouse model was established by using an ApoE KO strain mouse on a high-fat diet (HFD) to assess the effects of RBAP, conducted either orally or through injection. Additionally, in vitro experiments were conducted where the induction of THP-1 cells was conducted for the differentiation towards macrophages, and along with mouse RAW264.7 cells, were challenged with ox-LDL to evaluate the impact of RBAP. RESULTS: In this study, RBAP was found to reduce the production and downregulate TNF-α, IL-1ß, and IL-6 levels and inhibited the activation of the TLR4/MyD88/NF-κB signaling in atherosclerosis model mice, as well as in ox-LDL-challenged THP-1 cells and mouse RAW264.7 macrophages. RBAP's effectiveness also improved the enhancement of reverse cholesterol transport (RCT) and cholesterol removal to HDL and apoA1 by increasing the activity of genes related to cholesterol removal PPARγ/LXRα/ABCA1/ABCG1, both in ApoE-/- mice and in THP-1 cells and mouse RAW264.7 macrophages. Notably, RBAP exerted similar effects on atherosclerosis model mice and macrophages to those of TAK-242, an inhibitor of the TLR4 signaling. When RBAP and TAK-242 were applied simultaneously, the improvement was not enhanced compared with either RBAP or TAK-242 treatment alone. CONCLUSION: These findings suggest that RBAP, as a TLR4 inhibitor, has anti-atherosclerotic effects by improving inflammation and promoting cholesterol effection, indicating its therapeutic potential in intervening atherosclerosis.

Qinghao-Biejia Herb Pair attenuates SLE atherosclerosis by regulating macrophage polarization via ABCA1/G1-mediated cholesterol efflux.

ETHNOPHARMACOLOGICAL RELEVANCE: Qinghao-Biejia herb pair (QB) is the core herb pair of "Jieduquyuziyin prescription" and is one of the commonly used herb pairs for the clinical treatment of systemic lupus erythematosus (SLE). Previous studies have shown that QB reduces the expression of inflammatory cytokines like IL-6 and TNF-α in the serum and kidney of MRL/lpr mice. Additionally, it inhibits the expression of TLR4 and MyD88 in the kidney and aorta and reduces the deposition of renal complement C3 and aortic plaque after treatment. These findings suggest that QB has a preventive and therapeutic effect on lupus rats. AIM OF THE STUDY: This study sought to investigate the mechanisms underlying the anti-SLE combined with atherosclerosis activity of the Qinghao-Biejia herb pair. MATERIALS AND METHODS: Drug targets for QB were identified using the HERB database, while targets associated with SLE and atherosclerosis were retrieved from the GeneCards database. The intersection of these drug and disease targets was then analyzed using a protein-protein interaction (PPI) network with GO and KEGG pathway enrichment analysis. In vivo, apolipoprotein E-deficient (ApoE-/-) mice were induced to develop SLE-AS by intraperitoneal injection of pristane and continued feeding of a high-fat diet. The changes in relevant indexes were observed after 12 weeks of gavage treatment with hydroxychloroquine, QB, Q (Qinghao alone), and B (Biejia alone). Bone marrow-derived macrophages from ApoE-/- mice and Raw 264.7 macrophages were used to explore the mechanisms of QB treatment. RESULTS: The levels of inflammatory cytokines in serum and pathological liver changes in mice were improved to varying degrees in the treatment groups. Additionally, there was a reduction in aortic atheromatous plaque formation and some improvement in cholesterol efflux. Furthermore, QB suppressed the expression of inflammatory cytokines in M1 macrophages, suggesting a role in regulating macrophage polarization. CONCLUSION: QB demonstrates clear efficacy for treating SLE-AS, and its therapeutic mechanism may involve the regulation of macrophage phenotypes by promoting cholesterol efflux.

Ilexgenin A inhibits lipid accumulation in macrophages and reduces the progression of atherosclerosis through PTPN2/ERK1/2/ABCA1 signalling pathway.

Macrophage lipid accumulation indicates a pathological change in atherosclerosis. Ilexgenin A (IA), a pentacyclic triterpenoid compound, plays a role in preventing inflammation, bacterial infection, and fatty liver and induces a potential anti-atherogenic effect. However, the anti-atherosclerotic mechanism remains unclear. The present study investigated the effects of IA on lipid accumulation in macrophage-derived foam cells and atherogenesis in apoE-/- mice. Our results indicated that the expression of adenosine triphosphate-binding cassette transporter A1 (ABCA1) was up-regulated by IA, promoting cholesterol efflux and reducing lipid accumulation in macrophages, which may be regulated by the protein tyrosine phosphatase non-receptor type 2 (PTPN2)/ERK1/2 signalling pathway. IA attenuated the progression of atherosclerosis in high-fat diet-fed apoE-/- mice. PTPN2 knockdown with siRNA or treatment with an ERK1/2 agonist (Ro 67-7476) impeded the effects of IA on ABCA1 upregulation and cholesterol efflux in macrophages. These results suggest that IA inhibits macrophage lipid accumulation and alleviates atherosclerosis progression via the PTPN2/ERK1/2 signalling pathway.

Quantifying ABCA1/apoA-1 Signaling Pathways with AFM Imaging and Lipidomic Analysis.

The role of lipid metabolic pathways in the pathophysiology of primary open-angle glaucoma (POAG) has been thoroughly elucidated, with pathways involved in lipid-related disorders such as hypercholesterolemia and hyperlipoprotein accumulation being of particular interest. The ABCA1/apoA-1 transduction pathway moderates reverse cholesterol transport (RCT), facilitating the transport of free cholesterol (FC) and phospholipids (PL) and preventing intracellular lipid aggregates in retinal ganglion cells (RGCs) due to excess FCs and PLs. A deficiency of ABCA1 transporters, and thus, dysregulation of the ABCA1/apoA-1 transduction pathway, may potentiate cellular lipid accumulation, which affects the structural and mechanical features of the cholesterol-rich RGC membranes. Atomic force microscopy (AFM) is a cutting-edge imaging technique suitable for imaging topographical surfaces of a biological specimen and determining its mechanical properties and structural features. The versatility and precision of this technique may prove beneficial in understanding the effects of ABCA1/apoA-1 pathway downregulation and decreased cholesterol efflux in RGCs and their membranes. In this protocol, ABCA1-/- RGC mouse models are prepared over the course of 3 days and are then compared with non-knockout ABCA1 RGC mouse models through AFM imaging of topographical surfaces to examine the difference in membrane dynamics of knockout vs. non-knockout models. Intracellular and extracellular levels of lipids are quantified through high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS).

Inhibition of Toll-like Receptors Alters Macrophage Cholesterol Efflux and Foam Cell Formation.

Arterial macrophage cholesterol accumulation and impaired cholesterol efflux lead to foam cell formation and the development of atherosclerosis. Modified lipoproteins interact with toll-like receptors (TLR), causing an increased inflammatory response and altered cholesterol homeostasis. We aimed to determine the effects of TLR antagonists on cholesterol efflux and foam cell formation in human macrophages. Stimulated monocytes were treated with TLR antagonists (MIP2), and the cholesterol efflux transporter expression and foam cell formation were analyzed. The administration of MIP2 attenuated the foam cell formation induced by lipopolysaccharides (LPS) and oxidized low-density lipoproteins (ox-LDL) in stimulated THP-1 cells (p < 0.001). The expression of ATP-binding cassette transporters A (ABCA)-1, ABCG-1, scavenger receptor (SR)-B1, liver X receptor (LXR)-α, and peroxisome proliferator-activated receptor (PPAR)-γ mRNA and proteins were increased (p < 0.001) following MIP2 administration. A concentration-dependent decrease in the phosphorylation of p65, p38, and JNK was also observed following MIP2 administration. Moreover, an inhibition of p65 phosphorylation enhanced the expression of ABCA1, ABCG1, SR-B1, and LXR-α. TLR inhibition promoted the cholesterol efflux pathway by increasing the expression of ABCA-1, ABCG-1, and SR-B1, thereby reducing foam cell formation. Our results suggest a potential role of the p65/NF-kB/LXR-α/ABCA1 axis in TLR-mediated cholesterol homeostasis.

Identification and Molecular Simulation of Genetic Variants in ABCA1 Gene Associated with Susceptibility to Dyslipidemia in Type 2 Diabetes.

Genetic insights help us to investigate disease pathogenesis and risk. The ABCA1 protein encoded by ABCA1 is involved in transporting cholesterol across the cell membrane. Genetic variations in the ABCA1 gene are well documented; however, their role in the development of diabetic dyslipidemia still needs to be explored. This study aimed to identify the associations of rs757194699 (K1587Q) and rs2066714 (I883M) with dyslipidemia in type 2 diabetes and performed molecular simulations. In our case-control study, 330 individuals were divided equally into a diabetic dyslipidemia cases and a healthy controls. Allele-specific polymerase chain reaction and restriction fragment length polymorphism were performed to screen selected variants of the ABCA1 gene. Sanger sequencing was also performed to find genetic mutations in exon 5 of the ABCA1 gene. The C allele of rs757194699 was observed at a high frequency in cases compared to controls and followed the overdominant genetic model (p < 0.0001, OR:3.84; CI:1.67-8.82). The frequency of G allele of rs2066714 was significantly higher in cases compared to controls and followed the genetic model of codominant (p< 0.0001, OR: 39.61; CI:9.97-157.32), dominant (p < 0.0001,OR:59.59; CI:15.19-233.81), overdominant (p< 0.0001, OR:9.75; CI:3.16-30.11), and log-additive (p< 0.0001, OR:42.15; CI:11.08-160.40). In silico modeling and docking revealed that rs2066714 and rs757194699 produced deleterious conformational changes in the ABCA1 protein, resulting in alterations in the binding of the apoA1 protein. There were no genetic variations found in exon-5 in Sanger sequencing. The G allele of rs2066714 and C allele of rs757194699 in the ABCA1 gene were found to be risk alleles in the development of dyslipidemia in type 2 diabetes. These polymorphisms could alter the binding site of ABCA1 with apoA1 thus disturbs the reverse cholesterol transport.

Bridging the Gap Between the Bench and Bedside: Clinical Applications of High-density Lipoprotein Function.

Decades of research have reshaped our understanding of high-density lipoprotein (HDL) , shifting our focus from cholesterol (C) levels to multifaceted functionalities. Epidemiological studies initially suggested an association between HDL-C levels and cardiovascular disease (CVD) risk; however, such a simple association has not been indicated by recent studies. Notably, genome-wide studies have highlighted discrepancies between HDL-C levels and CVD outcomes, urging a deeper exploration of the role of HDL. The key to this shift lies in elucidating the role of HDL in reverse cholesterol transport (RCT), which is a fundamental anti-atherosclerotic mechanism. Understanding RCT has led to the identification of therapeutic targets and novel interventions for atherosclerosis. However, clinical trials have underscored the limitations of HDL-C as a therapeutic target, prompting the re-evaluation of the role of HDL in disease prevention. Further investigations have revealed the involvement of HDL composition in various diseases other than CVD, including chronic kidney disease, Alzheimer's disease, and autoimmune diseases. The anti-inflammatory, antioxidative, and anti-infectious properties of HDL have emerged as crucial aspects of its protective function, opening new avenues for novel biomarkers and therapeutic targets. Omics technologies have provided insights into the diverse composition of HDL, revealing disease-specific alterations in the HDL proteome and lipidome. In addition, combining cell-based and cell-free assays has facilitated the evaluation of the HDL functionality across diverse populations, offering the potential for personalized medicine. Overall, a comprehensive understanding of HDL multifunctionality leads to promising prospects for future clinical applications and therapeutic developments, extending beyond cardiovascular health.

Inflammatory corpuscle AIM2 facilitates macrophage foam cell formation by inhibiting cholesterol efflux protein ABCA1.

The inflammatory corpuscle recombinant absents in melanoma 2 (AIM2) and cholesterol efflux protein ATP binding cassette transporter A1(ABCA1) have been reported to play opposing roles in atherosclerosis (AS) plaques. However, the relationship between AIM2 and ABCA1 remains unclear. In this study, we explored the potential connection between AIM2 and ABCA1 in the modulation of AS by bioinformatic analysis combined with in vitro experiments. The GEO database was used to obtain AS transcriptional profiling data; screen differentially expressed genes (DEGs) and construct a weighted gene co-expression network analysis (WGCNA) to obtain AS-related modules. Phorbol myristate acetate (PMA) was used to induce macrophage modelling in THP-1 cells, and ox-LDL was used to induce macrophage foam cell formation. The experiment was divided into Negative Control (NC) group, Model Control (MC) group, AIM2 overexpression + ox-LDL (OE AIM2 + ox-LDL) group, and AIM2 short hairpin RNA + ox-LDL (sh AIM2 + ox-LDL) group. The intracellular cholesterol efflux rate was detected by scintillation counting; high-performance liquid chromatography (HPLC) was used to detect intracellular cholesterol levels; apoptosis levels were detected by TUNEL kit; levels of inflammatory markers (IL-1ß, IL-18, ROS, and GSH) were detected by ELISA kits; and levels of AIM2 and ABCA1 proteins were detected by Western blot. Bioinformatic analysis revealed that the turquoise module correlated most strongly with AS, and AIM2 and ABCA1 were co-expressed in the turquoise module with a trend towards negative correlation. In vitro experiments demonstrated that AIM2 inhibited macrophage cholesterol efflux, resulting in increased intracellular cholesterol levels and foam cell formation. Moreover, AIM2 had a synergistic effect with ox-LDL, exacerbating macrophage oxidative stress and inflammatory response. Silencing AIM2 ameliorated the above conditions. Furthermore, the protein expression levels of AIM2 and ABCA1 were consistent with the bioinformatic analysis, showing a negative correlation. AIM2 inhibits ABCA1 expression, causing abnormal cholesterol metabolism in macrophages and ultimately leading to foam cell formation. Inhibiting AIM2 may reverse this process. Overall, our study suggests that AIM2 is a reliable anti-inflammatory therapeutic target for AS. Inhibiting AIM2 expression may reduce foam cell formation and, consequently, inhibit the progression of AS plaques.

High-density lipoprotein infusion therapy: A review.

Increased cholesterol-rich, low-density, non-calcified atheromas as assessed by computer coronary tomography angiography analyses have been shown to predict myocardial infarction significantly better than coronary artery calcium score or the presence of obstructive coronary artery disease (CAD) as evaluated with standard coronary angiography. Low serum high-density lipoprotein (HDL) cholesterol values are an independent risk factor for CAD. Very small, lipid-poor preß-1 HDL particles have been shown to be most effective in promoting cellular cholesterol efflux. HDL infusions have been documented to reduce aortic atherosclerosis in cholesterol-fed animal models. However, human studies using infusions of either the HDL mimetic containing recombinant apolipoprotein (apo) A-I Milano or Cerenis Compound-001 with native recombinant apoA-I have been mainly negative in promoting coronary atherosclerosis progression as assessed by intravascular ultrasound. In contrast, a study using 7 weekly infusions of autologous delipidated HDL in six homozygous familial hypercholesterolemic patients was effective in promoting significant regression of low-density non-calcified coronary atheroma regression as assessed by computed coronary angiography. This therapy has received Food and Drug Administration approval. Commonwealth Serum Laboratories has carried out a large clinical endpoint trial using an HDL complex (native apoA-I with phospholipid), and the results were negative. Our purpose is to review animal and human studies using various forms of HDL infusion therapy to promote regression of atherosclerosis. In our view, differences in results may be due to: 1) the HDL preparations used, 2) the subjects studied, and 3) the methods used to assess coronary atherosclerosis.

Impaired high-density lipoprotein function and endothelial barrier stability in severe anaphylaxis.

BACKGROUND: Growing evidence demonstrates the importance of high- and low-density lipoprotein cholesterol in certain immune and allergy-mediated diseases. OBJECTIVE: This study aimed to evaluate levels of high- and low-density lipoprotein cholesterol and apolipoproteins A1 and B in sera from a cohort of patients presenting with hypersensitivity reactions. We further assessed the function of high-density lipoprotein particles as well as their involvement in the molecular mechanisms of anaphylaxis. METHODS: Lipid profile determination was performed in paired (acute and baseline) serum samples from 153 patients. Thirty-eight experienced a non-anaphylactic reaction and 115 had an anaphylactic reaction (88 moderate and 27 severe). Lecithin cholesterol acyl transferase activity was assessed in patient sera, and we also evaluated macrophage cholesterol efflux in response to the serum samples. Last, the effect of anaphylactic-derived high-density lipoprotein (HDL) particles on the endothelial barrier was studied. Detailed methods are provided in the Methods section in this article's Online Repository available at www.jacionline.org. RESULTS: Serum samples from severe anaphylactic reactions show statistically significant low levels of HDL cholesterol, low-density lipoprotein cholesterol, and apolipoproteins A1 and B, which points to their possible role as biomarkers. Specifically, HDL particles play a protective role in cardiovascular diseases. Using functional human serum cell assays, we observed impaired capacity of apolipoprotein B-depleted serum to induce macrophage cholesterol efflux in severe anaphylactic reactions. In addition, purified HDL particles from human anaphylactic sera failed to stabilize and maintain the endothelial barrier. CONCLUSION: These results encourage further research on HDL functions in severe anaphylaxis, which may lead to new diagnostic and therapeutic strategies.

LXR/CD38 activation drives cholesterol-induced macrophage senescence and neurodegeneration via NAD+ depletion.

Although dysregulated cholesterol metabolism predisposes aging tissues to inflammation and a plethora of diseases, the underlying molecular mechanism remains poorly defined. Here, we show that metabolic and genotoxic stresses, convergently acting through liver X nuclear receptor, upregulate CD38 to promote lysosomal cholesterol efflux, leading to nicotinamide adenine dinucleotide (NAD+) depletion in macrophages. Cholesterol-mediated NAD+ depletion induces macrophage senescence, promoting key features of age-related macular degeneration (AMD), including subretinal lipid deposition and neurodegeneration. NAD+ augmentation reverses cellular senescence and macrophage dysfunction, preventing the development of AMD phenotype. Genetic and pharmacological senolysis protect against the development of AMD and neurodegeneration. Subretinal administration of healthy macrophages promotes the clearance of senescent macrophages, reversing the AMD disease burden. Thus, NAD+ deficit induced by excess intracellular cholesterol is the converging mechanism of macrophage senescence and a causal process underlying age-related neurodegeneration.