Prognostic Impact of Blood Lipid Profile in Patients With Advanced Solid Tumors Treated With Immune Checkpoint Inhibitors: A Multicenter Cohort Study.

BACKGROUND: Specific components of lipid profile seem to differently impact on immune activity against cancer and unraveling their prognostic role in patients with solid cancer treated with immune checkpoint inhibitors (ICIs) is needed. MATERIALS AND METHODS: We retrospectively collected baseline clinicopathological characteristics including circulating lipid profile (total cholesterol [TC], triglycerides [TG], low-density lipoproteins [LDL], high-density lipoproteins [HDL]) of patients with consecutive solid cancer treated with ICIs, and we investigated their role in predicting clinical outcomes. RESULTS: At a median follow-up of 32.9 months, among 430 enrolled patients, those with TC ≥ 200 mg/dl showed longer median progression-free survival (mPFS; 6.6 vs. 4.7 months, P = .4), although not reaching statistical significance, and significantly longer median overall survival (mOS; 19.4 vs. 10.8 months, P = .02) compared to those with TC < 200 mg/dl. Conversely, patients with TG ≥150 mg/dl displayed shorter PFS (3.4 vs. 5.1 months, P = .02) and OS (7.1 vs. 12.9 months, P = .009) compared to those with TG <150 mg/dl. TC and TG were then combined in a "LIPID score" identifying three subgroups: good-risk (GR) (TC ≥200 mg/dl and TG <150 mg/dl), intermediate-risk (IR) (TC <200 mg/dl and TG <150 mg/dl or TC ≥200 mg/dl and TG ≥150 mg/dl) and poor-risk (PR) (TC <200 mg/dl and TG ≥150 mg/dl). The mPFS of GR, IR, and PR groups was 7.8, 4.3, and 2.5 months, respectively (P = .005); mOS of GR, IR, and PR was 20.4, 12.4, and 5.3 months, respectively (P < .001). At multivariable analysis, the PR profile represented an independent poor prognostic factor for both PFS and OS. CONCLUSIONS: We developed a lipid score that defined subgroups of patients with cancer who differently benefit from ICIs. Further mechanistic insights are warranted to clarify the prognostic and predictive role of lipid profile components in patients treated with ICIs.

The role of blood cholesterol quality in patients with advanced cancer receiving immune checkpoint inhibitors.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) became the standard of care for several solid tumors. A limited fraction of patients (pts) achieves a long-term benefit. Plasmatic and intracellular cholesterol levels have emerged as promising biomarkers. The aim of the present study was to determine whether cholesterol efflux capacity (CEC), mediated by serum transporters (ABCA1 and ABCG1) and passive diffusion (PD), impacts on clinical outcome of advanced non-small cell lung cancer (NSCLC) and metastatic renal cell carcinoma (mRCC) pts treated with ICIs. MATERIAL AND METHODS: We retrospectively enrolled advanced NSCLC and mRCC pts consecutively treated with ICIs between October 2013 and October 2018. CEC and cholesterol loading capacity (CLC) were assessed by well-established specific cell models. As primary endpoint, CEC, PD and CLC were correlated with overall survival (OS) while the effects of these parameters on progression-free survival (PFS) and clinical benefit (CB), defined as complete/partial response or stable disease, represented secondary endpoints. RESULTS: NSCLC accounted for 94.2% of 70 enrolled cases, and serum sample suitable for CEC and PD determination was available in 68. Blood cholesterol and serum ABCA1, ABCG1, PD and CLC were associated with outcomes (OS, PFS and CB) at univariate analysis. At the multivariate analysis, only PD confirmed its positive prognostic value in terms of OS, PFS and CB. CONCLUSION: The favorable impact of cholesterol PD on clinical outcome might reflect its main conformation in mature HDL particles which potentially shape an inflamed context, ultimately promoting ICI efficacy. Further prospective studies are needed to support our findings and uncover targetable pathways.

High-Density Lipoprotein and Long-Term Incidence and Progression of Aortic Valve Calcification: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Aortic valve calcification (AVC) shares pathological features with atherosclerosis. Lipoprotein components have been detected in aortic valve tissue, including HDL (high-density lipoprotein). HDL measures have inverse associations with cardiovascular disease, but relationships with long-term AVC progression are unclear. We investigated associations of HDL cholesterol, HDL-particle number and size, apoC3-defined HDL subtypes, and, secondarily, CETP (cholesteryl ester transfer protein) mass and activity, with long-term incidence and progression of AVC. METHODS: We used linear mixed-effects models to evaluate the associations of baseline HDL indices with AVC. AVC was quantified by Agatston scoring of up to 3 serial computed tomography scans over a median of 8.9 (maximum 11.2) years of follow-up in the Multi-Ethnic Study of Atherosclerosis (n=6784). RESULTS: After adjustment, higher concentrations of HDL-C (high-density lipoprotein cholesterol), HDL-P (HDL particles), large HDL-P, and apoC3-lacking HDL-C were significantly associated with lower incidence/progression of AVC. Neither small or medium HDL-P nor apoC3-containing HDL-C was significantly associated with AVC incidence/progression. When included together, a significant association was observed only for HDL-C, but not for HDL-P. Secondary analyses showed an inverse relationship between CETP mass, but not activity, and AVC incidence/progression. In exploratory assessments, inverse associations for HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL with AVC incidence/progression were more pronounced for older, male, and White participants. ApoC3-containing HDL-C only showed a positive association with AVC in these subgroups. CONCLUSIONS: In a multiethnic population, HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL-C were inversely associated with long-term incidence and progression of AVC. Further investigation of HDL composition and mechanisms could be useful in understanding pathways that slow AVC.

Effects of a dietary intervention with Mediterranean vs lacto-ovo vegetarian diets on HDL function: Results from the CARDIVEG study.

BACKGROUND AND AIM: HDL-cholesterol efflux capacity (CEC) has been shown to be a better cardiovascular (CVD) risk marker than serum HDL concentration. Several foods and nutrients have been shown to improve HDL functions, however no effective dietetic nor pharmacological strategy is available to increase CEC. This study aims to evaluate the possible effect of Mediterranean diet (MD) and lacto-ovo-vegetarian diet (VD) on HDL function in a group of clinically healthy subjects at low-to-moderate CVD risk. METHODS AND RESULTS: Thirty apparently healthy subjects with a low-to-moderate cardiovascular risk profile (21 F; mean age: 51.3 ± 9.7 years) were randomly assigned to a 3-month MD or VD diet and then crossed. Participants on VD showed a reduction in total HDL CEC by 8.99% (p < 0.001) as well as a reduction in ABCA1 mediated-CEC by 18.62% (p < 0.001) compared to participants on MD. Regarding CEC mediated by aqueous diffusion, no significant changes were observed after treatment with either diet. Finally, a significant positive association between CEC mediated by the ABCA1 transporter and adiponectin was found (r = 0.462; p = 0.010). CONCLUSION: The results of this study suggest that HDL activity in promoting cholesterol efflux and thereby reducing the concentration of pro-atherogenic lipoproteins was more effective in participants undergoing MD than VD. Based on these findings, the MD could be considered a better therapeutic strategy for cardiovascular prevention than VD. CLINICAL TRIAL REGISTRATION URL: http://www. CLINICALTRIALS: gov. Unique identifier: NCT02641834.

Effect of a PCSK9 inhibitor and a statin on cholesterol efflux capacity: A limitation of current cholesterol-lowering treatments?

BACKGROUND: Cellular cholesterol efflux is a key step in reverse cholesterol transport that may impact on atherosclerotic cardiovascular risk. The process may be reliant on the availability of apolipoprotein (apo) B-100-containing lipoproteins to accept cholesterol from high-density lipoprotein. Evolocumab and atorvastatin are known to lower plasma apoB-100-containing lipoproteins that could impact on cholesterol efflux capacity (CEC). METHODS: We conducted a 2-by-2 factorial trial of the effects of subcutaneous evolocumab (420 mg every 2 weeks) and atorvastatin (80 mg daily) for 8 weeks on CEC in 81 healthy, normolipidaemic men. The capacity of whole plasma and apoB-depleted plasma, including ATP-binding cassette transporter A1 (ABCA1)-mediated and passive diffusion, to efflux cholesterol, was measured. RESULTS: Evolocumab and atorvastatin independently decreased whole plasma CEC (main effect p < .01 for both). However, there were no significant effects of evolocumab and atorvastatin on apoB-depleted plasma, ABCA1-mediated and passive diffusion-mediated CEC (p > .05 in all). In the three intervention groups combined, the reduction in whole plasma CEC was significantly correlated with the corresponding reduction in plasma apoB-100 concentration (r = .339, p < .01). In the evolocumab monotherapy group, the reduction in whole plasma CEC was also significantly correlated with the corresponding reduction in plasma lipoprotein(a) concentration (r = .487, p < .05). CONCLUSIONS: In normolipidaemic men, evolocumab and atorvastatin decrease the capacity of whole plasma to efflux cellular cholesterol. These effects may be chiefly owing to a fall in the availability of apoB-100-containing lipoproteins. Reduction in circulating lipoprotein(a) may also contribute to the decrease in whole plasma cholesterol efflux with evolocumab monotherapy.

Measures of high-density lipoprotein function in men and women with severe aortic stenosis.

BACKGROUND: Calcification of the aortic valve is a common heart valve disorder, in some cases leading to clinically impactful severe aortic stenosis (AS). Sex-specific differences in aortic valve calcification (ACV) exist, with women having a lower burden of calcification than men as measured by computed tomography; however, the pathophysiological mechanism that leads to these differences remains unclear. METHODS: Using cultured human Tamm-Horsfall protein 1 (THP-1) macrophages and human aortic valve interstitial cells, the effects of high-density lipoprotein (HDL) particles isolated from the plasma of men and women with severe AS were studied for cholesterol efflux capacity (CEC). RESULTS: HDL-CEC was assessed in 46 patients with severe AS, n = 30 men, n = 16 women. ATP-Binding Cassette A1 (ABCA1)-mediated HDL-CEC was measured from human cultured THP-1 macrophages to plasma HDL samples. Women with severe AS had more ABCA1-mediated HDL-CEC, as compared to men (8.50 ± 3.90% cpm vs. 6.80 ± 1.50% cpm, P = 0.04). HDL pre-ß1 and α-particles were higher in woman than in men by spectral density, (pre-ß1 HDL, 20298.29 ± 1076.15 vs. 15,661.74 ± 789.00, P = 0.002, and α-HDL, 63006.35 ± 756.81 vs. 50,447.00 ± 546.52, P = 0.03). Lecithin-cholesterol acyltransferase conversion of free cholesterol into cholesteryl esters was higher in women than men (16.44 ± 9.11%/h vs. 12.00 ± 8.07%/h, P = 0.03). CONCLUSIONS: Sex-specific changes in various parameters of HDL-CEC were found in patients with severe AS. Sex-based modifications in HDL functionality by HDL-CEC might account for the reduced burden of calcification in women vs. men with severe AS. Therefore, future studies should target sex-related pathways in AS to help to improve understanding and treatment of AS. Sex specifc differences in AVC and differences associated with HDL function in men and women with severe AS. When compared to men, women had higher preß-HDL and α-HDL migrating particles, higher cholesterol efflux to HDL, and higher lecithin cholesterol acyl transferase (LCAT) activity, possibly indicating that improved reverse cholesterol transport may be protective against worsened calcification.

Functional pasta consumption in healthy volunteers modulates ABCG1-mediated cholesterol efflux capacity of HDL.

BACKGROUNDS AND AIMS: Prevention of cardiovascular (CV) disease is considered a central issue in public health and great attention is payed to nutritional approaches, including consumption of functional foods to reduce CV risk in individuals without indications for anti-atherosclerotic drugs. Cholesterol efflux capacity (CEC) is an important anti-atherogenic property of HDL and a marker of CV risk. We evaluated the effect of a daily consumption of an innovative whole-wheat synbiotic pasta, compared to a control whole-wheat pasta, on serum ATP binding cassette G1 (ABCG1)-mediated CEC in healthy overweight or obese individuals. METHODS AND RESULTS: Study participants (n = 41) were randomly allocated to either innovative or control pasta, consumed daily for twelve weeks. Serum CEC was measured before and after the dietary intervention, by a well-established radioisotopic technique on Chinese Hamster Ovary Cells transfected with human ABCG1. The innovative synbiotic pasta consumption was associated to a significantly higher post treatment/baseline ratio of ABCG1-mediated CEC values with respect to control pasta (mean ratio 1.05 ± 0.037 and 0.95 ± 0.042 respectively, p < 0.05). Analysis of the relationship between ABCG1-mediated CEC and glycemia, homocysteine, total folates and interleukin-6 showed specific changes in the correlations between HDL function and glycemia, oxidative and inflammatory markers only after synbiotic pasta consumption. CONCLUSION: This is the first report on serum CEC improvement obtained by a new synbiotic functional pasta consumption, in absence of lipid profile modifications, in overweight/obese participants. This pilot study suggests that a simple dietary intervention can be a promising approach to CV preservation through improving of athero-protective HDL function.

High-Density Lipoprotein Functionality as a New Pharmacological Target on Cardiovascular Disease: Unifying Mechanism That Explains High-Density Lipoprotein Protection Toward the Progression of Atherosclerosis.

The formation of the atherosclerotic plaque that is characterized by the accumulation of abnormal amounts of cholesterol-loaded macrophages in the artery wall is mediated by both inflammatory events and alterations of lipid/lipoprotein metabolism. Reverse transport of cholesterol opposes the formation and development of atherosclerotic plaque by promoting high density lipoprotein (HDL)-mediated removal of cholesterol from peripheral macrophages and its delivery back to the liver for excretion into the bile. Although an inverse association between HDL plasma levels and the risk of cardiovascular disease (CVD) has been demonstrated over the years, several studies have recently shown that the antiatherogenic functions of HDL seem to be mediated by their functionality, not always associated with their plasma concentrations. Therefore, assessment of HDL function, evaluated as the capacity to promote cell cholesterol efflux, may offer a better prediction of CVD than HDL levels alone. In agreement with this idea, it has recently been shown that the assessment of serum cholesterol efflux capacity (CEC), as a metric of HDL functionality, may represent a predictor of atherosclerosis extent in humans. The purpose of this narrative review is to summarize the current evidence concerning the role of cholesterol efflux capacity that is important for evaluating CVD risk, focusing on pharmacological evidences and its relationship with inflammation. We conclude that HDL therapeutics are a promising area of investigation but strategies for identifying efficacy must move beyond the idea of simply raising static HDL-cholesterol levels and toward methods of measuring the dynamics of HDL particle remodeling and the generation of lipid-free apolipoprotein A-I (apoA-I). In this way, apoA-I, unlike mature HDL, can promote the greatest extent of cholesterol efflux relieving cellular cholesterol toxicity and the inflammation it causes.

Plasma cholesterol homeostasis, HDL remodeling and function during the acute phase reaction.

Acute phase reaction (APR) is a systemic inflammation triggered by several conditions associated with lipid profile alterations. We evaluated whether APR also associates with changes in cholesterol synthesis and absorption, HDL structure, composition, and cholesterol efflux capacity (CEC). We analyzed 59 subjects with APR related to infections, oncologic causes, or autoimmune diseases and 39 controls. We detected no difference in markers of cholesterol synthesis and absorption. Conversely, a significant reduction of LpA-I- and LpAI:AII-containing HDL (-28% and -44.8%, respectively) and of medium-sized HDL (-10.5%) occurred in APR. Total HDL CEC was impaired in APR subjects (-18%). Evaluating specific CEC pathways, we found significant reductions in CEC by aqueous diffusion and by the transporters scavenger receptor B-I and ABCG1 (-25.5, -41.1 and -30.4%, respectively). ABCA1-mediated CEC was not affected. Analyses adjusted for age and gender provided similar results. In addition, correcting for HDL-cholesterol (HDL-C) levels, the differences in aqueous diffusion total and ABCG1-CEC remained significant. APR subjects displayed higher levels of HDL serum amyloid A (+20-folds; P = 0.003). In conclusion, APR does not associate with cholesterol synthesis and absorption changes but with alterations of HDL composition and a marked impairment of HDL CEC, partly independent of HDL-C serum level reduction.

Cholesterol efflux and reverse cholesterol transport.

Both alterations of lipid/lipoprotein metabolism and inflammatory events contribute to the formation of the atherosclerotic plaque, characterized by the accumulation of abnormal amounts of cholesterol and macrophages in the artery wall. Reverse cholesterol transport (RCT) may counteract the pathogenic events leading to the formation and development of atheroma, by promoting the high-density lipoprotein (HDL)-mediated removal of cholesterol from the artery wall. Recent in vivo studies established the inverse relationship between RCT efficiency and atherosclerotic cardiovascular diseases (CVD), thus suggesting that the promotion of this process may represent a novel strategy to reduce atherosclerotic plaque burden and subsequent cardiovascular events. HDL plays a primary role in all stages of RCT: (1) cholesterol efflux, where these lipoproteins remove excess cholesterol from cells; (2) lipoprotein remodeling, where HDL undergo structural modifications with possible impact on their function; and (3) hepatic lipid uptake, where HDL releases cholesterol to the liver, for the final excretion into bile and feces. Although the inverse association between HDL plasma levels and CVD risk has been postulated for years, recently this concept has been challenged by studies reporting that HDL antiatherogenic functions may be independent of their plasma levels. Therefore, assessment of HDL function, evaluated as the capacity to promote cell cholesterol efflux may offer a better prediction of CVD than HDL levels alone. Consistent with this idea, it has been recently demonstrated that the evaluation of serum cholesterol efflux capacity (CEC) is a predictor of atherosclerosis extent in humans.

Impact of systemic inflammation and autoimmune diseases on apoA-I and HDL plasma levels and functions.

The cholesterol of high-density lipoproteins (HDLs) and its major proteic component, apoA-I, have been widely investigated as potential predictors of acute cardiovascular (CV) events. In particular, HDL cholesterol levels were shown to be inversely and independently associated with the risk of acute CV diseases in different patient populations, including autoimmune and chronic inflammatory disorders. Some relevant and direct anti-inflammatory activities of HDL have been also recently identified targeting both immune and vascular cell subsets. These studies recently highlighted the improvement of HDL function (instead of circulating levels) as a promising treatment strategy to reduce inflammation and associated CV risk in several diseases, such as systemic lupus erythematosus and rheumatoid arthritis. In these diseases, anti-inflammatory treatments targeting HDL function might improve both disease activity and CV risk. In this narrative review, we will focus on the pathophysiological relevance of HDL and apoA-I levels/functions in different acute and chronic inflammatory pathophysiological conditions.

Impaired serum cholesterol efflux capacity in rheumatoid arthritis and systemic lupus erythematosus.

OBJECTIVES: The marked cardiovascular risk in autoimmune diseases is only partly explained. The capacity of high-density lipoproteins (HDL) to promote cell cholesterol efflux is a property with a well-known anti-atherogenic significance, but is also involved in functional modulation of endothelial and immune cells. The aim of this work was to evaluate HDL functionality with respect to cell cholesterol efflux in rheumatoid arthritis (RA) and systemic lupus erythemathosus (SLE) patients. METHODS: We evaluated serum cholesterol efflux capacity (CEC) of apoB-depleted serum, which mainly reflects HDL activity, from 30 RA and 30 SLE patients, and from 30 healthy controls by radioisotopic ex-vivo systems discriminating between the specific pathways of cholesterol efflux. RESULTS: RA patients presented impairment of ATP-binding cassette G1-mediated CEC that correlated with disease activity. SLE patients showed a more complex pattern of modifications unrelated to disease activity, with marked reduction of ATP-binding cassette G1-mediated CEC and impairment of ATP-binding cassette A1-mediated CEC. The relationship between specific pathways of CEC values and serum total HDL differed between groups and there was no relationship with autoantibody profile or current therapy. CONCLUSIONS: CEC is impaired in RA and SLE, with a specific mechanism pattern in each disease not depending on serum HDL levels. These findings provide a new mechanism for the increased atherosclerotic risk in RA and SLE patients.

Intersecting Blood Cytokines With Cholesterol Parameters to Profile Patients With Advanced Solid Tumors Receiving Immune Checkpoint Inhibitors.

The study investigated the relationship between serum proinflammatory cytokine levels, cholesterol metabolism, and clinical outcome in cancer patients undergoing immune checkpoint inhibitors (ICIs). Peripheral blood was collected before therapy from ICI-treated advanced cancer patients. We retrospectively assessed plasma total cholesterol (TC), ABCA1- and ABCG1-mediated cholesterol efflux (CE), passive diffusion (PD), cholesterol loading capacity (CLC), and serum IL-6, IL-10, and TNF-α. The association between blood cholesterol parameters and inflammatory cytokines and their effect on overall survival (OS), progression-free survival (PFS), and clinical benefit (CB) from ICIs were statistically assessed. Among 70 consecutively enrolled patients (nonsmall cell lung cancer: 94%; renal cell carcinoma: 6%), TC, CLC, and cholesterol PD resulted significantly higher in IL-6low and IL-10low cases (P<0.05), whereas ABCA1-mediated CE was increased in IL-10high patients (P=0.018). Uni- and multivariable analysis revealed meaningfully longer OS and PFS in IL-6low (HR 2.13 and 2.97, respectively) and IL-10low (HR 3.17 and 2.62) groups. At univariate analysis all cholesterol-related indices significantly correlated with OS and PFS, whereas at multivariate only high PD was validated as a protection factor (OS, HR 0.75; PFS, HR 0.84). Finally, uni- and multivariable showed a statistically significant inverse association of CB with ABCG1-CE (OR 0.62), as with IL-6 (OR 0.13) and IL-10 (OR 0.10). In-depth characterization of the interplay between blood cholesterol metabolism and immune-inflammatory cytokines might provide novel insights into the complex relationship among cancer, inflammation, lipids profile, and response to immunotherapy.

ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects.

The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a high-fidelity tonometer. J774 macrophages, labeled with [(3)H]cholesterol and stimulated to express ABCA1, were exposed to sera; the difference between cholesterol efflux from stimulated and unstimulated cells provided specific ABCA1-mediated CEC. PWV is inversely correlated with ABCA1-dependent CEC (r = -0.183; P = 0.018). Moreover, controlling for age, sex, body mass index, mean arterial pressure, serum LDL, HDL-cholesterol, and fasting plasma glucose, PWV displays a significant negative regression on ABCA1-dependent CEC (ß = -0.204; 95% confidence interval, -0.371 to -0.037). The finding that ABCA1-dependent CEC, but not serum HDL cholesterol level (r = -0.002; P = 0.985), is a significant predictor of PWV in healthy subjects points to the relevance of HDL function in vascular physiology and arterial stiffness prevention.

Rac1 and cholesterol metabolism in macrophage.

In the early stages of atherosclerotic lesion development, cholesterol is mostly present as esterified cholesterol stored in macrophage cytoplasmic lipid droplets. However, when the lesion evolves, free cholesterol accumulates in other compartments, such as lysosomes and plasma membrane. A number of studies support a role for intracellular cholesterol content and distribution in regulating several cell functions. Particularly, membrane free cholesterol content has a specific effect on signaling pathways involved in regulating cell motility and organization of the actin cytoskeleton. These processes are regulated by several signaling pathways including the small GTPase Rac1. Rac1 belongs to the Rho GTPases of the Ras protein superfamily involved in the regulation of multiple cell functions, including cell proliferation, chemotaxis, phagocytosis, degranulation, and superoxide production. In this review, we discuss the role of Rac1 in macrophage with respect to cholesterol metabolism and trafficking as critical aspects for the development of atherosclerotic plaque.

Cholesterol efflux capacity is increased in subjects with familial hypercholesterolemia in a retrospective case-control study.

Familial Hypercholesterolemia (FH) is characterized by an increase in Low-Density Lipoprotein Cholesterol (LDL-C) and by premature Cardiovascular Disease (CVD). However, it remains to be fully elucidated if FH impairs cholesterol efflux capacity (CEC), and whether CEC is related to lipoprotein subfraction distribution. This study aimed at comparing FH patients and age, sex and BMI matched controls in terms of LDL and HDL subfraction distribution as well as CEC. Forty FH patients and 80 controls, matched for age, sex and BMI, were enrolled in this case-control study. LDL and HDL subfractions were analyzed using the Quantimetrix Lipoprint System. CEC was evaluated as aq-CEC and ABCA1-CEC. FH subjects showed a significantly higher concentration of all LDL subfractions, and a shift from large to small HDL subfraction pattern relative to controls. FH subjects with previous CVD event had smaller LDL lipoproteins than controls and FH subjects without previous CVD event. Both aq-CEC and ABCA1-CEC were increased in FH patients with respect to controls. To conclude, FH subjects had a metabolic profile characterized not only by higher LDL-C but also by shift from large to small HDL subfraction phenotype. However, FH subjects showed an increase CEC than controls.

Novel mutations of ABCA1 transporter in patients with Tangier disease and familial HDL deficiency.

The objective of the study was the characterization of ABCA1 gene mutations in 10 patients with extremely low HDL-cholesterol. Five patients (aged 6 months to 76 years) presented with splenomegaly and thrombocytopenia suggesting the diagnosis of Tangier disease (TD). Three of them were homozygous for novel mutations either in intron (c.4465-34A>G) or in exons (c.4376delT and c.5449C>T), predicted to encode truncated proteins. One patient was compound heterozygous for a nucleotide insertion (c.1758_1759insG), resulting in a truncated protein and for a nucleotide substitution c.4799A>G, resulting in a missense mutation (p.H1600R). The last TD patient, found to be heterozygous for a known mutation (p.D1009Y), had a complete defect in ABCA1-mediated cholesterol efflux in fibroblasts, suggesting the presence of a second undetected mutant allele. Among the other patients, four were asymptomatic, but one, with multiple risk factors, had severe peripheral artery disease. Three of these patients were heterozygous for known mutations (p.R130K+p.N1800H, p.R1068C, p.N1800H), while two were carriers of novel mutations (c.1195-27G>A and c.396_397insA), predicted to encode truncated proteins. The pathogenic effect of the two intronic mutations (c. 1195-27G>A and c.4465-34A>G) was demonstrated by the analysis of the transcripts of splicing reporter mutant minigenes expressed in COS-1 cells. Both mutations activated an intronic acceptor splice site which resulted in a partial intron retention in mature mRNA with the production of truncated proteins. This study confirms the allelic heterogeneity of TD and suggests that the diagnosis of TD must be considered in patients with an unexplained splenomegaly, associated with thrombocytopenia and hypocholesterolemia.

Plasma HDL pattern, cholesterol efflux and cholesterol loading capacity of serum in carriers of a novel missense variant (Gly176Trp) of endothelial lipase.

BACKGROUND: Loss of function variants of LIPG gene encoding endothelial lipase (EL) are associated with primary hyperalphalipoproteinemia (HALP), a lipid disorder characterized by elevated plasma levels of high density lipoprotein cholesterol (HDL-C). OBJECTIVE: Aim of the study was the phenotypic and genotypic characterization of a family with primary HALP. METHODS: HDL subclasses distribution was determined by polyacrylamide gradient gel electrophoresis. Serum content of preß-HDL was assessed by (2D)-electrophoresis. Cholesterol efflux capacity (CEC) of serum mediated by ABCA1, ABCG1 or SR-BI was assessed using cells expressing these proteins. Cholesterol loading capacity (CLC) of serum was assayed using cultured human macrophages. Next generation sequencing was used for DNA analysis. Plasma EL mass was determined by ELISA. RESULTS: Three family members had elevated plasma HDL-C, apoA-I and total phospholipids, as well as a reduced content of preß-HDL. These subjects were heterozygous carriers of a novel variant of LIPG gene [c.526 G>T, p.(Gly176Trp)] found to be deleterious in silico. Plasma EL mass in carriers was lower than in controls. CEC of sera mediated by ABCA1 and ABCG1 transporters was substantially reduced in the carriers. This effect was maintained after correction for serum HDL concentration. The sera of carriers were found to have a higher CLC in cultured human macrophages than control sera. CONCLUSION: The novel p.(Gly176Trp) variant of endothelial lipase is associated with changes in HDL composition and subclass distribution as well as with functional changes affecting cholesterol efflux capacity of serum which suggest a defect in the early steps of revere cholesterol transport.

Probucol treatment is associated with an ABCA1-independent mechanism of cholesterol efflux to lipid poor apolipoproteins from foam cell macrophages.

Objective: Probucol is a cholesterol-lowering agent whose ability to prevent atherosclerosis is currently under study. Herein, we investigate the putative mechanism of probucol by observation of changes in cellular cholesterol efflux and lipid droplet morphology in macrophages. Results: The inhibitory activity of probucol was assessed in non-foam or foam cell macrophages expressing ABCA1 generated by treatment with fetal calf serum (FCS) alone or in combination with acetylated LDL, respectively. Probucol inhibited cholesterol efflux to apolipoprotein A-I (apoA-I) by 31.5±0.1% in THP-1 non-foam cells and by 18.5±0.2% in foam cells. In probucol-treated non-foam THP-1 cells, nascent high density lipoprotein (nHDL) particles with a diameter < 7 nm were generated, while in probucol-treated THP-1 foam cells nHDL particles of > 7 nm in diameter containing cholesterol were produced. Foam cells also displayed a significant accumulation of free cholesterol at the plasma membrane, as measured by percent cholestenone formed. Intracellularly, there was a significant decrease in lipid droplet number and an increase in size in probucol-treated THP-1 foam cells when compared to non-treated cells. Conclusions: We report for the first time that probucol is unable to completely inhibit cholesterol efflux in foam cells to the same extent as in non-foam cells. Indeed, functional nHDL is released from foam cells in the presence of probucol. This difference in inhibitory effect could potentially be explained by changes in the plasma membrane pool as well as intracellular cholesterol storage independently of ABCA1.