HDL and atherothrombotic vascular disease

Hepatocytic lipocalin-2 controls HDL metabolism and atherosclerosis via Nedd4-1-SR-BI axis in mice

High-density lipoprotein (HDL) metabolism is regulated by complex interplay between the scavenger receptor group B type 1 (SR-BI) and multiple signaling molecules in the liver. Here, we show that lipocalin-2 (Lcn2) is a key regulator of hepatic SR-BI, HDL metabolism, and atherosclerosis. Overexpression of human Lcn2 in hepatocytes attenuates the development of atherosclerosis via SR-BI in western-diet-fed Ldlr-/- mice, whereas hepatocyte-specific ablation of Lcn2 has the opposite effect. Mechanistically, hepatocyte Lcn2 improves HDL metabolism and alleviates atherogenesis by blocking Nedd4-1-mediated SR-BI ubiquitination at K500 and K508. The Lcn2-improved HDL metabolism is abolished in mice with hepatocyte-specific Nedd4-1 or SR-BI deletion and in SR-BI (K500A/K508A) mutation mice. This study identifies a regulatory axis from Lcn2 to HDL via blocking Nedd4-1-mediated SR-BI ubiquitination and demonstrates that hepatocyte Lcn2 may be a promising target to improve HDL metabolism to treat atherosclerotic cardiovascular diseases.

Apolipoprotein M bound sphingosine 1-phosphate suppresses NETosis through activating S1P1 and S1P4

The pleiotropic effects of high-density lipoprotein (HDL), including its protective properties against sepsis, are attributed to the sphingosine 1-phosphate and apolipoprotein M (ApoM) that are carried on the lipoproteins. In this study, we attempted to elucidate the possible mechanisms underlying the sepsis coagulopathic state by considering the modulation of NETosis. Our results revealed that in a lipopolysaccharide-induced sepsis mouse model, the levels of NETosis markers, such as plasma DNA and histone, were elevated in ApoM-knockout (KO) mice and attenuated in ApoM-overexpressing mice. In ApoM-KO mice, the survival rate decreased and the occurrence rates of coagulopathy and organ injury increased following the administration of histone. Treatment with a conditioned medium of ApoM-overexpressing cells attenuated the observed NETosis in HL-60S cells that differentiated into neutrophils and were inhibited through the suppression of S1P1 or S1P4. The attenuation of PKCδ and PKCα/β by S1P1 and S1P4 activation may also be involved. In ApoM-overexpressing mice, coagulopathy and organ injuries were attenuated following an injection of histone; these effects were partially inhibited by S1P1, 3, S1P4, or S1P1 antagonists. Furthermore, the exogenous administration of ApoM protected ApoM-KO mice that were challenged with histone from developing NETosis. In conclusion, the ApoM/S1P axis protects against NETosis through the attenuation of PKC activation by S1P1 and S1P4. The development of drugs targeting the ApoM/S1P axis may be beneficial for the treatment of pathological conditions involving uncontrolled NETosis, such as sepsis.

Increased BMI and Blood Lipids Are Associated With a Hypercoagulable State in the Moli-sani Cohort

The coagulation system can be assessed by the thrombin generation (TG) assay, and increased TG peak height, endogenous thrombin potential (ETP), and velocity index are associated with an increased risk of thrombosis. Obesity had been reported to increase TG and is associated with dyslipidemia, which also predisposes to atherosclerotic cardiovascular disease (CVD). However, the effect of the blood lipid profile on TG has not been studied extensively. To gain more insight into the associations of TG, body mass index (BMI) and lipid profile, we studied TG in relation to these parameters in a large Italian population cohort, the Moli-sani study (N = 22,546; age ≥ 35 years; 48% men). TG was measured in plasma samples collected at the enrollment of subjects in the Moli-sani study. TG was triggered with 1 or 5 pM tissue factor, and TG parameters lag time, peak, ETP, time-to-peak (TTP) and velocity index (VI). Additionally, thrombomodulin was added to assess the function of the activated protein C system during TG. In both women and men, overweight (BMI 25–30 kg/m²) and obesity (BMI > 30 kg/m²) were significantly associated with higher ETP, peak and VI (all p < 0.001). High total cholesterol, triglycerides and LDL-cholesterol levels were significantly associated with increased ETP and peak (all p < 0.001). Linear regression analysis revealed that the ETP is positively associated with both plasma LDL and HDL cholesterol levels, whereas the velocity index is positively associated with HDL cholesterol. Additionally, ETP, peak and VI were significantly associated with the plasma triglycerides content. In conclusion, our study shows significant associations of high BMI and blood lipid levels with increased TG parameters, and this hypercoagulability may partly explain the increased risk of CVD in individuals with obesity and/or dyslipidemia.

High Density Lipoprotein and Its Precursor Protein Apolipoprotein A1 as Potential Therapeutics to Prevent Anthracycline Associated Cardiotoxicity

Cardiovascular disease and cancer are the leading causes of death in developed societies. Despite their effectiveness, many cancer therapies exhibit deleterious cardiovascular side effects such as cardiotoxicity and heart failure. The cardiotoxic effects of anthracyclines such as doxorubicin are the most well-characterized of cardiotoxic anti-cancer therapies. While other anti-neoplastic drugs also induce cardiotoxicity, often leading to heart failure, they are beyond the scope of this review. This review first summarizes the mechanisms of doxorubicin-induced cardiotoxicity. It then reviews emerging preclinical evidence that high density lipoprotein and its precursor protein apolipoprotein A1, which are known for their protective effects against ischemic cardiovascular disease, may also protect against doxorubicin-induced cardiotoxicity both directly and indirectly, when used therapeutically.

Establishment of Clinical Prediction Model Based on the Study of Risk Factors of Stroke in Patients With Type 2 Diabetes Mellitus

Purpose: Stroke has sparked global concern as it seriously threatens people's life, bringing about dramatic health burdens on patients, especially for type 2 diabetes mellitus (T2DM) patients. Therefore, a risk scoring model is urgently valuable for T2DM patients to predict the risk of stroke incidence and for positive health intervention. Methods: We randomly divided 4,335 T2DM patients into two groups, training set (n = 3,252) and validation set (n = 1,083), at the ratio of 3:1. Characteristic variables were then selected based on the data of training set through least absolute shrinkage and selection operator regression. Three models were established to verify predictive ability. Foundation model was composed of basic information and physical indicators. Biochemical model consisted of biochemical indexes. Integrated model combined the above two models. Data of three models were then put into logistic regression analysis to form nomogram prediction models. Tools including C index, calibration plot, and curve analysis were implemented to test discrimination, calibration, and clinical use. To select the best predicting model, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were put into effect. Results: Eleven risk factors were determined, including age, duration of T2DM, estimated glomerular filtration rate, systolic blood pressure, diastolic blood pressure, low-density lipoprotein, high-density lipoprotein, triglyceride, body mass index, uric acid, and glycosylated hemoglobin A_1c, all with significant P-values through logistic regression analysis. In the training set, areas under the curve of three models were 0.810, 0.819, and 0.884, whereas in the validation set, they were 0.836, 0.832, and 0.909. Through calibration plot, the S:P values in the training set were 0.836, 0.754, and 0.621 and were 0.918, 0.682, and 0.666 separately in the validation set. In terms of the decision curve analysis, the risk thresholds were, respectively, 8-73%, 8-98%, and 8%~ in the training set and 8-70%, 8-90%, and 8-95% in the validation set. With the aid of NRI and IDI, integrated model is proved to be the best model in training set and validation set. Besides, internal validation was conducted on all the subjects in this study, and the C index was 0.890 (0.873-0.907). Conclusion: This study established a model predicting risk of stroke for T2DM patients through a community-based survey.

Preclinical and clinical results regarding the effects of a plant-based antidiabetic formulation versus well established antidiabetic molecules

Diabetes mellitus (DM) is a complex syndrome with debilitating long-term complications, comprising alterations of carbohydrate, protein and lipid metabolisms, along increased oxidative stress and chronic low-grade inflammation. Diet management and plant-based formulations can improve the metabolic status of patients, being used as adjuvants of classic antidiabetic therapy. The purpose of our study was to evaluate the impact of a plant-based antidiabetic formulation (PBAF), containing Vaccinium myrtillus, Ribes nigrum, Rosa canina and Capsicum annuum, on the increased oxidative burden found in diabetes mellitus, comparing it with the effects of metformin and gliclazide. Firstly, we characterized the individual plant-derived components of this formulation and also assessed their in vitro radical scavenging capacity. We devised a preclinical study protocol to examine the impact of the PBAF, along metformin and gliclazide, on tissue histology as well as on the redox status of tissue, mitochondria, serum and serum lipoproteins of alloxan-induced diabetic Wistar rats. Subsequently, we assessed their long-term impact on the redox status of serum and isolated serum lipoproteins of type 2 DM (T2DM) patients, taking into consideration their cardiometabolic profile. In the preclinical stage, we found that PBAF was able to enhance total serum antioxidant defense, while metformin yielded the best results regarding the advanced glycation and protein/lipid oxidation of serum and of serum lipoproteins. The latter also improved overall serum redox status and HDL redox function. Also, antidiabetic treatment seemed to increase mitochondrial redox activity, without overturning overall tissue redox balance. Histologically, liver and brain tissues of treated diabetic rats were fairly similar to those of non-diabetic rats. In T2DM patients, the most striking results involved the effects on serum lipoproteins. The tested PBAF exerted protective antioxidant effects on low-density and, especially, on high density lipoproteins. We conclude that this formulation might constitute a good addition to the well-established pharmacological approach of DM, contributing to the reduction of overall oxidative burden.

Associations Between Apolipoprotein A1, High-Density Lipoprotein Cholesterol, and Urinary Cytokine Levels in Elderly Males and Females

There exists a close relationship between cardiovascular diseases and chronic kidney disease. Apolipoprotein A1 and high-density lipoprotein (HDL) cholesterol are widely used as cardiovascular risk markers but they also have anti-inflammatory properties. The aim of this study was to investigate any associations between HDL levels and cytokine levels in urine. We randomly selected 90 urine samples from the Prospective Investigation of the Vasculature in Uppsala Seniors Study (41 males and 49 females). The samples were analyzed with 2 multiplex assays, Multiplex Inflammation I and Cardiovascular II kits (Olink Bioscience, Uppsala, Sweden). We analyzed the correlations between 158 cytokines in urine with apolipoprotein A1, HDL cholesterol, apolipoprotein B, and low-density lipoprotein cholesterol. There were strong correlations for apolipoprotein A1 and HDL cholesterol with individual cytokines. After adjustment for multiplicity testing, there were 33 significant correlations between apolipoprotein A1 and cytokine levels and 14 of these were also significantly correlated with HDL cholesterol. The strongest associations were observed for IL-1α, SPON2, RAGE, PAR-1, TRAIL-R2, IL-4RA, TNFRSF11A, and SCF. A total of 28 out of 33 correlations were negative, indicating a negative relationship between apolipoprotein A1 and urinary cytokines. The study shows a negative correlation between apolipoprotein A1 and HDL cholesterol and urinary cytokine levels. The finding is in agreement with the anti-inflammatory properties of HDL.

Myeloperoxidase Associates With Degenerative Remodeling and Rupture of the Saccular Intracranial Aneurysm Wall

Rupture of a saccular intracranial aneurysm (sIA) is often fatal. Thus, early detection of rupture-prone sIAs is vital. Myeloperoxidase (MPO), derived mainly from neutrophils, associates with sIA rupture, and therefore its role in sIA pathogenesis warrants further studies. We analyzed MPO and its association with other histological markers in 36 (16 unruptured and 20 ruptured) sIA samples by immunohistochemistry. MPO was present in all studied sIAs, and its expression associated with wall inflammatory cell infiltrations (r = 0.50, 0.63, and 0.75, all p ≤ 0.002), degenerative remodeling (p = 0.002) and rupture (p = 0.003). MPO associated strongly with the presence of organized luminal thrombi (p < 0.001), which also stained positive for MPO. Polymorphonuclear MPO+ cells were detected in the sIA walls, indicating neutrophils as MPO-source. MPO correlated strongly with accumulation of oxidized lipids (r = 0.67, p < 0.001) and loss of smooth muscle cells (r = -0.68, p < 0.001), suggesting that MPO is a relevant source of oxidative stress leading to cell death in the sIA wall. Furthermore, MPO associated with erythrocyte fragmentation (r = 0.74, p < 0.001) and iron deposition (p = 0.041), 2 outcomes known to amplify MPO-dependent oxidative stress. Taken together, these results suggest that MPO associates with degenerative remodeling predisposing to sIA wall rupture and may serve as a biomarker of a rupture-prone sIA wall.

Modified and Dysfunctional Lipoproteins in Atherosclerosis: Effectors or Biomarkers?

Atherosclerotic diseases are the leading cause of mortality in industrialized countries. Correspondingly, studying the pathogenesis of atherosclerosis and developing new methods for its diagnostic and treatment remain in the focus of current medicine and health care. This review aims to discuss the mechanistic role of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in atherogenesis. In particular, the generally accepted hypothesis about the key role of oxidized LDL in atherogenesis is questioned, and an alternative concept of multiple modification of LDL is presented. The fundamental question discussed in this review is whether LDL and HDL are effectors or biomarkers, or both. This is important for understanding whether lipoproteins are a therapeutic target or just diagnostic indicators.

Current Therapies Focused on High-Density Lipoproteins Associated with Cardiovascular Disease

High-density lipoproteins (HDL) comprise a heterogeneous family of lipoprotein particles divided into subclasses that are determined by density, size and surface charge as well as protein composition. Epidemiological studies have suggested an inverse correlation between High-density lipoprotein-cholesterol (HDL-C) levels and the risk of cardiovascular diseases and atherosclerosis. HDLs promote reverse cholesterol transport (RCT) and have several atheroprotective functions such as anti-inflammation, anti-thrombosis, and anti-oxidation. HDLs are considered to be atheroprotective because they are associated in serum with paraoxonases (PONs) which protect HDL from oxidation. Polyphenol consumption reduces the risk of chronic diseases in humans. Polyphenols increase the binding of HDL to PON1, increasing the catalytic activity of PON1. This review summarizes the evidence currently available regarding pharmacological and alternative treatments aimed at improving the functionality of HDL-C. Information on the effectiveness of the treatments has contributed to the understanding of the molecular mechanisms that regulate plasma levels of HDL-C, thereby promoting the development of more effective treatment of cardiovascular diseases. For that purpose, Scopus and Medline databases were searched to identify the publications investigating the impact of current therapies focused on high-density lipoproteins.

Relationships of oxidized HDL with blood coagulation and fibrinolysis in patients with type 2 diabetes mellitus

Although oxidization of LDL is known to be a crucial step for atherosclerotic progression, the significance of oxidized HDL remains to be clarified. The purpose of this study was to determine the relationships of oxidized HDL with blood coagulation and fibrinolysis in patients with diabetes. The subjects were outpatients with type 2 diabetes (n = 163; median hemoglobin A1c, 6.9%). Activities of blood coagulation and fibrinolysis were evaluated by levels of thrombin-anti-thrombin complex (TAT) and plasmin-α2 plasmin inhibitor complex (PIC), respectively. Relationships of oxidized HDL with TAT and PIC were investigated by using linear regression analysis and logistic regression analysis. Oxidized HDL showed a significant inverse correlation with TAT and a marginally significant correlation with PIC (Spearman's rank correlation coefficient: TAT, - 0.205 [p < 0.01]; PIC, - 0.135 [p = 0.087]). Prevalence of high TAT was significantly lower in the 3rd tertile group for oxidized HDL than in its 1st tertile (20.4 vs. 5.6%, p < 0.05), and prevalence of high PIC was marginally significantly lower in the 3rd tertile group for oxidized HDL than in its 1st tertile (40.7 vs. 24.1%, p = 0.099). In multivariate logistic regression analysis using age, gender, smoking, alcohol drinking, BMI, hemoglobin A1c, therapy for dyslipidemia, therapy for diabetes and anti-coagulation therapy as explanatory variables, odds ratios for high TAT and high PIC in the 3rd tertile group for oxidized HDL versus its 1st tertile group were significantly lower than the reference level of 1.00 (high TAT: 0.19 [0.04-0.99], p < 0.05; high PIC: 0.33 [0.12-0.95], p < 0.05). The frequency of high TAT or high PIC was lower in the higher tertile group for oxidized HDL than in its lower tertile group. Thus, oxidized HDL is thought to be inversely associated with both blood coagulation and fibrinolysis in patients with type 2 diabetes.

Involvement of CETP (Cholesteryl Ester Transfer Protein) in the Shift of Sphingosine-1-Phosphate Among Lipoproteins and in the Modulation of its Functions

OBJECTIVE

Sphingosine-1-phosphate (S1P) is a vasoprotective lipid mediator. About two thirds of plasma S1P rides on high-density lipoprotein (HDL), and several pleiotropic properties of HDL have been ascribed to S1P. In human subjects, CETP (cholesteryl ester transfer protein) greatly influences HDL quantities. In this study, we attempted to elucidate the roles of CETP in the metabolism of S1P.

APPROACH AND RESULTS

We overexpressed CETP in mice that lacked CETP and found that CETP overexpression decreased the HDL level but failed to modulate the levels of S1P and apolipoprotein M (apoM), a carrier of S1P, in the total plasma. We observed, however, that the distribution of S1P and apoM shifted from HDL to apoB-containing lipoproteins. When we administered C₁₇S1P bound to apoM-containing lipoprotein, C₁₇S1P and apoM were rapidly transferred to apoB-containing lipoproteins in CETP-overexpressing mice. When HDL containing C₁₇S1P was mixed with low-density lipoprotein ex vivo, C₁₇S1P shifted to the low-density lipoprotein fraction independent of the presence of CETP. Concordant with these results, apoM was distributed mainly to the same fraction as apo AI in a CETP-deficient subject, although apoM was also detected in apo AI-poor fractions in a corresponding hypercholesterolemia subject. About the bioactivities of S1P carried on each lipoprotein, S1P riding on apoB-containing lipoproteins induced the phosphorylation of Akt (AKT8 virus oncogene cellular homolog) and eNOS (endothelial nitric oxide synthase) in human umbilical vein endothelial cells, and CETP overexpression increased insulin secretion and sensitivity, which was inhibited by an S1P receptor 1 or 3 antagonist.

CONCLUSIONS

CETP modulates the distribution of S1P among lipoproteins, which affects the bioactivities of S1P.

Dysfunctional high-density lipoproteins in coronary heart disease: implications for diagnostics and therapy

Low plasma levels of high-density lipoprotein (HDL) cholesterol are associated with increased risks of coronary heart disease. HDL mediates cholesterol efflux from macrophages for reverse transport to the liver and elicits many anti-inflammatory and anti-oxidative activities which are potentially anti-atherogenic. Nevertheless, HDL has not been successfully targeted by drugs for prevention or treatment of cardiovascular diseases. One potential reason is the targeting of HDL cholesterol which does not capture the structural and functional complexity of HDL particles. Hundreds of lipid species and dozens of proteins as well as several microRNAs have been identified in HDL. This physiological heterogeneity is further increased in pathologic conditions due to additional quantitative and qualitative molecular changes of HDL components which have been associated with both loss of physiological function and gain of pathologic dysfunction. This structural and functional complexity of HDL has prevented clear assignments of molecules to the functions of normal HDL and dysfunctions of pathologic HDL. Systematic analyses of structure-function relationships of HDL-associated molecules and their modifications are needed to test the different components and functions of HDL for their relative contribution in the pathogenesis of atherosclerosis. The derived biomarkers and targets may eventually help to exploit HDL for treatment and diagnostics of cardiovascular diseases.

Smooth Muscle Cell Foam Cell Formation, Apolipoproteins, and ABCA1 in Intracranial Aneurysms: Implications for Lipid Accumulation as a Promoter of Aneurysm Wall Rupture

Saccular intracranial aneurysm (sIA) aneurysm causes intracranial hemorrhages that are associated with high mortality. Lipid accumulation and chronic inflammation occur in the sIA wall. A major mechanism for lipid clearance from arteries is adenosine triphosphate-binding cassette A1 (ABCA1)-mediated lipid efflux from foam cells to apolipoprotein A-I (apoA-I). We investigated the association of wall degeneration, inflammation, and lipid-related parameters in tissue samples of 16 unruptured and 20 ruptured sIAs using histology and immunohistochemistry. Intracellular lipid accumulation was associated with wall remodeling (p = 0.005) and rupture (p = 0.020). Foam cell formation was observed in smooth muscle cells, in addition to CD68- and CD163-positive macrophages. Macrophage infiltration correlated with intracellular lipid accumulation and apolipoproteins, including apoA-I. ApoA-I correlated with markers of lipid accumulation and wall degeneration (p = 0.01). ApoA-I-positive staining colocalized with ABCA1-positive cells particularly in sIAs with high number of smooth muscle cells (p = 0.003); absence of such colocalization was associated with wall degeneration (p = 0.017). Known clinical risk factors for sIA rupture correlated inversely with apoA-I. We conclude that lipid accumulation associates with sIA wall degeneration and risk of rupture, possibly via formation of foam cells and subsequent loss of mural cells. Reduced removal of lipids from the sIA wall via ABCA1-apoA-I pathway may contribute to this process.

Lipoprotein binding to anionic biopolyelectrolytes and the effect of glucose on nanoplaque formation in arteriosclerosis and Alzheimer's disease

Arteriosclerosis with its clinical sequelae (cardiac infarction, stroke, peripheral arterial occlusive disease) and vascular/Alzheimer dementia not only result in far more than half of all deaths but also represent dramatic economic problems. The reason is, among others, that diabetes mellitus is an independent risk factor for both disorders, and the number of diabetics strongly increases worldwide. More than one-half of infants in the first 6months of life have already small collections of macrophages and macrophages filled with lipid droplets in susceptible segments of the coronary arteries. On the other hand, the authors of the Bogalusa Heart Study found a strong increase in the prevalence of obesity in childhood that is paralleled by an increase in blood pressure, blood lipid concentration, and type 2 diabetes mellitus. Thus, there is a clear linkage between arteriosclerosis/Alzheimer's disease on the one hand and diabetes mellitus on the other hand. Furthermore, it has been demonstrated that distinct apoE isoforms on the blood lipids further both arteriosclerotic and Alzheimer nanoplaque formation and therefore impair flow-mediated vascular reactivity as well. Nanoplaque build-up seems to be the starting point for arteriosclerosis and Alzheimer's disease in their later full clinical manifestation. In earlier work, we could portray the anionic biopolyelectrolytes syndecan/perlecan as blood flow sensors and lipoprotein receptors in cell membrane and vascular matrix. We described extensively molecular composition, conformation, form and function of the macromolecule heparan sulfate proteoglycan (HS-PG). In two supplementary experimental settings (ellipsometry, myography), we utilized isolated HS-PG for in vitro nanoplaque investigations and isolated human coronary artery segments for in vivo tension measurements. With the ellipsometry-based approach, we were successful in establishing a direct connection on a molecular level between diabetes mellitus on the one side and arteriosclerosis/Alzheimer's disease on the other side. Application of glucose at a concentration representative for diabetics and leading to glycation of proteins and lipids, entailed a significant increase in arteriosclerotic and Alzheimer nanoplaque formation. IDLapoE4/E4 was by far superior to IDLapoE3/E3 in plaque build-up, both in diabetic and non-diabetic patients. Recording vascular tension of flow-dependent reactivity in blood substitute solution and under application of different IDLapoE isoforms showed an impaired vasorelaxation for pooled IDL and IDLapoE4/E4, thus confirming the ellipsometric investigations. Incubation in IDLapoE0/E0 (apoE "knockout man"), however, resulted in a massive flow-mediated contraction, also complemented by strongly aggregated nanoplaques. In contrast, HDL was shown to present a powerful protection against nanoplaque formation on principle, both in the in vitro model and the in vivo scenario on the endothelial cell membrane. The competitive interplay with LDL is highlighted through the flow experiment, where flow-mediated, HDL-induced vasodilatation remains untouched by additional incubation with LDL. This is due to the four times higher affinity for the proteoglycan receptor of HDL as compared to LDL. Taken together, the studies demonstrate that while simplistic, the ellipsometry approach and the endothelial-mimicking proteoglycan-modified surfaces provide information on the initial steps of lipoprotein-related plaque formation, which correlates with findings on endothelial cells and blood vessels, and afford insight into the role of lipoprotein deposition and exchange phenomena at the onset of these pathophysiologies.

HDL functionality in reverse cholesterol transport--Challenges in translating data emerging from mouse models to human disease

Whereas LDL-derived cholesterol accumulates in atherosclerotic lesions, HDL particles are thought to facilitate removal of cholesterol from the lesions back to the liver thereby promoting its fecal excretion from the body. Because generation of cholesterol-loaded macrophages is inherent to atherogenesis, studies on the mechanisms stimulating the release of cholesterol from these cells and its ultimate excretion into feces are crucial to learn how to prevent lesion development or even induce lesion regression. Modulation of this key anti-atherogenic pathway, known as the macrophage-specific reverse cholesterol transport, has been extensively studied in several mouse models with the ultimate aim of applying the emerging knowledge to humans. The present review provides a detailed comparison and critical analysis of the various steps of reverse cholesterol transport in mouse and man. We attempt to translate this in vivo complex scenario into practical concepts, which could serve as valuable tools when developing novel HDL-targeted therapies.