Abnormal HDL lipid and protein composition following pediatric cancer treatment: an associative study.

BACKGROUND: Long-term childhood cancer survivors (CCS) are at high risk of having dyslipidemia including low high density lipoprotein cholesterol (HDL-C). However, little is known about the prevalence of low HDL-C and the impact of therapy exposure on HDL composition early after treatment is terminated. METHODS: This associative study included 50 children and adolescents who had completed their cancer treatments (< 4 years). Clinical characteristics (demographic, diagnosis, treatment, anthropometric parameters), fasting plasma lipids, apoliporoteins (Apo) A-I and composition of HDL fractions (HDL2 and HDL3) were assessed. Data were stratified according to the presence of dyslipidemia and median doses of therapeutic agents and compared using Fisher exact or Mann-Whitney tests. Univariate binary logistic regression analyses were carried out to evaluate the associations between the clinical and biochemical characteristics and having low HDL-C. Composition of HDL2 and HDL3 particles was assessed in a sub-group of 15 patients and compared to 15 age- and sex-matched healthy controls using Wilcoxon paired test. RESULTS: Of the 50 pediatric cancer patients included in this study (mean age: 11.30 ± 0.72 y; mean time since end of treatment: 1.47 ± 0.12 y; male: 38%), 8 had low HDL-C (16%), all of which were adolescent at diagnosis. Higher doses of doxorubicin were associated with lower HDL-C and Apo A-I levels. In hypertriglyceridemic patients and compared to normolipidemics, triglycerides (TG) content was greater in HDL2 and HDL3 fractions whereas esterified cholesterol (EC) content was lower in HDL2. Enrich TG content of HDL3 and lower EC of HDL2 was found in patients exposed to ≥ 90 mg/m2 doxorubicin. Factors positively associated with the risk of having low HDL-C were age, being overweight or obese and exposure to doxorubicin ≥ 90 mg/m2. Compared to healthy controls, a sub-group of 15 patients showed higher TG and free cholesterol (FC) content of HDL2 and HDL3 and lower EC content in HDL3. CONCLUSIONS: Overall, we found abnormalities in HDL-C and Apo A-I levels and in HDL composition early after pediatric cancer treatment that are influenced by age, overweight or obesity status and exposure to doxorubicin.

Enhancement of High-Density Lipoprotein (HDL) Quantity and Quality by Regular and Habitual Exercise in Middle-Aged Women with Improvements in Lipid and Apolipoprotein Profiles: Larger Particle Size and Higher Antioxidant Ability of HDL.

Regular exercise, especially aerobic exercise, is beneficial for increasing serum high-density lipoprotein-cholesterol (HDL-C) levels in the general population. In addition to the HDL-C quantity, exercise enhances HDL functionality, antioxidants, and cholesterol efflux. On the other hand, the optimal intensity and frequency of exercise to increase HDL quantity and enhance HDL quality in middle-aged women need to be determined. The current study was designed to compare the changes in HDL quantity and quality among middle-aged women depending on exercise intensity, frequency, and duration; participants were divided into a sedentary group (group 1), a middle-intensity group (group 2), and a high-intensity group (group 3). There were no differences in anthropometric parameters among the groups, including blood pressure, muscle mass, and handgrip strength. Although there was no difference in serum total cholesterol (TC) among the groups, the serum HDL-C and apolipoprotein (apo)A-I levels remarkably increased to 17% and 12%, respectively, in group 3. Serum low-density lipoprotein-cholesterol (LDL-C), glucose, triglyceride, and the apo-B/apoA-I ratio were remarkably decreased in the exercise groups depending on the exercise intensity; group 3 showed 13%, 10%, and 45% lower LDL-C, glucose, and triglyceride (TG), respectively, than group 1. The hepatic and muscle damage parameter, aspartate aminotransferase (AST), was significantly decreased in the exercise groups, but high-sensitivity C-reactive protein (CRP), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GTP) were similar in the three groups. In LDL, the particle size was increased 1.5-fold (p < 0.001), and the oxidation extent was decreased by 40% with a 23% lower TG content in group 3 than in group 1. In the exercise groups (groups 2 and 3), LDL showed the slowest electromobility with a distinct band intensity compared to the sedentary group (group 1). In HDL2, the particle size was 2.1-fold increased (p < 0.001) in the exercise group (group 3) with a 1.5-fold increase in TC content compared to that in group 1, as well as significantly enhanced antioxidant abilities, paraoxonase (PON) activity, and ferric ion reduction ability (FRA). In HDL3, the particle size was increased 1.2-fold with a 45% reduction in TG in group 3 compared to group 1. With increasing exercise intensity, apoA-I expression was increased in HDL2 and HDL3, and PON activity and FRA were enhanced (p < 0.001). In conclusion, regular exercise in middle-aged women is associated with the elevation of serum HDL-C and apoA-I with the enhancement of HDL quality and functionality and an increase in the TC content, particle size, and antioxidant abilities. With the reduction in TG and oxidized products in LDL and HDL, lipoproteins could have more anti-atherogenic properties through regular exercise in an intensity-dependent manner.

Quantitative NMR-Based Lipoprotein Analysis Identifies Elevated HDL-4 and Triglycerides in the Serum of Alzheimer's Disease Patients.

Alzheimer's disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative lipoprotein analysis in a local cohort of cognitively impaired elderly and control subjects using standardized nuclear magnetic resonance (NMR) spectroscopy. A commercially available quantitative NMR-based assay covering 112 lipoprotein main and subtype variables was used to investigate blood serum samples from a moderate cohort size of 161 persons (71 female, 90 male), including measures of quality control. Additionally, clinical metadata and cerebrospinal fluid AD biomarkers were collected and used for analysis. High-density lipoprotein (HDL) HDL-4 subfraction levels were mostly high in female individuals with mild cognitive impairment (MCI), followed by AD. Low-density lipoprotein (LDL) LDL-2 cholesterol was slightly elevated in male AD patients. HDL-2 apolipoprotein Apo-A1, HDL-2 phospholipids, and HDL-3 triglycerides were highly abundant in AD and MCI women compared to men. When considering clinical biomarkers (Aß, tau), very low-density lipoprotein (VLDL) VLDL-1 and intermediate-density lipoprotein (IDL) triglycerides were substantially higher in AD compared to MCI. In addition, triglyceride levels correlated positively with dementia. Different lipoprotein serum patterns were identified for AD, MCI, and control subjects. Interestingly, HDL-4 and LDL-2 cholesterol parameters revealed strong gender-specific changes in the context of AD-driven dementia. As gender-based comparisons were based on smaller sub-groups with a low n-number, several statistical findings did not meet the significance threshold for multiple comparisons testing. Still, our finding suggests that serum HDL-4 parameters and various triglycerides correlate positively with AD pathology which could be a read-out of extended lipids traveling through the blood-brain barrier, supporting amyloid plaque formation processes. Thereof, we see herein a proof of concept that this quantitative NMR-based lipoprotein assay can generate important and highly interesting data for refined AD diagnosis and patient stratification, especially when larger cohorts are available.

Overweight and obesity in polycystic ovary syndrome: association with inflammation, oxidative stress and dyslipidaemia.

Polycystic ovary syndrome (PCOS) is associated with altered lipid profile and increased small, dense LDL particles (sdLDL). Considering that paraoxonase 1 (PON1) is an antioxidative enzyme located on HDL particles, the aim of this study was to investigate the connection between oxidative stress (OS) and PON1 activity with lipoprotein subclasses in PCOS depending on obesity. In 115 PCOS patients, lipoprotein subclasses distributions were determined by gradient gel electrophoresis. OS status was assessed by total oxidative status (TOS), advanced oxidation protein products, malondialdehyde (MDA), prooxidant-antioxidant balance (PAB), total antioxidative status (TAS) and superoxide dismutase (SOD) and PON1 activity. Overweight/obese PCOS patients (n 55) had increased OS compared with normal weight patients (n 60). In addition, overweight/obese group had lower HDL size and higher proportion of HDL 3a subclasses (P < 0·05). PAB was in negative correlation with HDL 2a (P < 0·001), whereas MDA and SOD correlated positively with HDL 3 subclasses (P < 0·05). Serum PON1 activity was positively associated with proportions of PON1 activity on HDL 2b (P < 0·05) and 2a (P < 0·01), but negatively with the proportion on HDL 3 particles (P < 0·01). LDL B phenotype patients had increased TAS, SOD and PON1 activity on HDL 2b, but decreased PON1 activity on HDL 3 subclasses. OS is associated with altered lipoprotein subclasses distribution in PCOS patients. Obesity in PCOS affects the profile of HDL subclasses, reflected through the reduced proportion of PON1 activity on HDL 3 subclasses in the presence of sdLDL particles.

Correlation between HDL2, HDL3 and serum ferritin levels with fatty liver and NAFLD activity score (NAS) in liver histology of organ donors.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is one of the most important liver diseases. High-density lipoprotein (HDL) has anti-atherogenic properties and its reduction can be associated with fatty liver. Serum ferritin levels are usually elevated in patients with NAFLD. This study aimed to evaluate the correlation between HDL subtypes and serum ferritin levels with evidence of NAFLD in liver histology of organ donors. METHODS: One hundred organ donor patients who were eligible for the study were included in the study and ferritin; HDL2 and HDL3 were measured in blood samples. Donated liver tissue biopsy specimens were evaluated for fatty liver and NAFLD activity score (NAS). In addition, AST and ALT were measured in recipients 24 h after transplant. All data abstracted and analyzed statistically. RESULTS: Serum HDL2 levels and HDL2/HDL3 ratio in patients with NAS > 1 were significantly lower (P < 0.05). Serum levels of HDL3 and ferritin were not significantly associated with NAS >1 (P > 0.05). In addition, serum ferritin > 1000 ng/ml in organ donors associated with increased AST and ALT levels 24 h after transplantation in the liver organ recipient. CONCLUSIONS: Lower HDL2 values and HDL2/HDL3 ratio were associated with increased NAFLD activity score, but HDL3 and ferritin did not show such a relationship. In addition, higher levels of ferritin in organ donors may be associated with increased AST and ALT 24 h after liver transplantation in the organ recipient.

Enterically derived high-density lipoprotein restrains liver injury through the portal vein.

The biogenesis of high-density lipoprotein (HDL) requires apoA1 and the cholesterol transporter ABCA1. Although the liver generates most of the HDL in the blood, HDL synthesis also occurs in the small intestine. Here, we show that intestine-derived HDL traverses the portal vein in the HDL3 subspecies form, in complex with lipopolysaccharide (LPS)-binding protein (LBP). HDL3, but not HDL2 or low-density lipoprotein, prevented LPS binding to and inflammatory activation of liver macrophages and instead supported extracellular inactivation of LPS. In mouse models involving surgical, dietary, or alcoholic intestinal insult, loss of intestine-derived HDL worsened liver injury, whereas outcomes were improved by therapeutics that elevated and depended upon raising intestinal HDL. Thus, protection of the liver from injury in response to gut-derived LPS is a major function of intestinally synthesized HDL.

Apolipoprotein C-II and C-III preferably transfer to both high-density lipoprotein (HDL)2 and the larger HDL3 from very low-density lipoprotein (VLDL).

Triglyceride hydrolysis by lipoprotein lipase (LPL), regulated by apolipoproteins C-II (apoC-II) and C-III (apoC-III), is essential for maintaining normal lipid homeostasis. During triglyceride lipolysis, the apoCs are known to be transferred from very low-density lipoprotein (VLDL) to high-density lipoprotein (HDL), but the detailed mechanisms of this transfer remain unclear. In this study, we investigated the extent of the apoC transfers and their distribution in HDL subfractions, HDL2 and HDL3. Each HDL subfraction was incubated with VLDL or biotin-labeled VLDL, and apolipoproteins and lipids in the re-isolated HDL were quantified using western blotting and high-performance liquid chromatography (HPLC). In consequence, incubation with VLDL showed the increase of net amount of apoC-II and apoC-III in the HDL. HPLC analysis revealed that the biotin-labeled apolipoproteins, including apoCs and apolipoprotein E, were preferably transferred to the larger HDL3. No effect of cholesteryl ester transfer protein inhibitor on the apoC transfers was observed. Quantification of apoCs levels in HDL2 and HDL3 from healthy subjects (n = 8) showed large individual differences between apoC-II and apoC-III levels. These results suggest that both apoC-II and apoC-III transfer disproportionately from VLDL to HDL2 and the larger HDL3, and these transfers might be involved in individual triglyceride metabolism.

Changes in plasma HDL and its subcomponents HDL2b and HDL3 regulate inflammatory response by modulating SOCS1 signaling to affect severity degree and prognosis of sepsis.

OBJECTIVES: To explore if SOCS1 is regulated by plasma HDL and its subcomponents HDL2b and HDL3 to affect inflammatory reaction then to influence the severity degree and prognosis of sepsis. METHODS: One hundred sepsis patients in ICU and 85 normal control persons from October 2018 to October 2019 in our hospital were enrolled. Adult male C57BL/6 mice were used to establish sepsis model by CLP method. HDL, CRP, and WBC count of human were measured using an auto-analyzer. Plasma HDL, IL-1ß, and TNF-α proteins levels of mice were measured with ELISA. Microfluidic chip was used for plasma HDL2b and HDL3 detections. SOCS1 in liver and spleen of mice were measured by qRT-PCR. The relationship between plasma HDL//HDL2b and inflammatory indices/SOCS1 in liver/spleen was analyzed with spearman correlation coefficient method. The sepsis patients/mice were divided into non-survival and survival groups. The sepsis patients were divided into severe and mild sepsis patients based on the SOFA score or divided into high and low score groups according to the APACHE II score. The sepsis mice were divided into high and low score group based on the modified sepsis severity score criterion. RESULTS: Plasma HDL and HDL2b levels were significantly declined (P < 0.01), while HDL3 was normal in both sepsis patients and mice (P > 0.05). Plasma HDL and HDL2b were negatively associated with the serum CRP concentration and positively correlated with the prognosis and severity in sepsis patients (P < 0.05). Moreover, the downregulated plasma HDL but not HDL2b was negatively related to increased SOCS1 mRNA levels in liver and spleen of mice, which were positively connected with TNF-α and IL-1ß protein levels (P < 0.05). CONCLUSIONS: Plasma HDL is downregulated in sepsis, which may facilitate inflammatory reaction then activate the SOCS1 signaling to regulate the severity and affect prognosis of sepsis. The decline of plasma HDL2b content could aggravate the severity and poor prognosis of sepsis through facilitating inflammatory reaction. The plasma HDL3 is not involved in sepsis. The more and further explorations may be needed.

Association of proportion of the HDL-cholesterol subclasses HDL-2b and HDL-3 and macrovascular events among patients undergoing hemodialysis.

Altered high-density lipoprotein cholesterol (HDL-C) subclass distribution in hemodialysis (HD) patients is well documented. Aim of this study is to investigate the relationship between HDL-C subclass distribution and macrovascular events in patients undergoing HD. A total of 164 prevalent HD patients and 71 healthy individuals in one hospital-facilitated clinic were enrolled from May 2019 to July 2019 and individual HD patients was follow-up for one year. Macrovascular events (cerebral stroke, coronary heart disease) were recorded in the study period. The HDL-2b, HDL-3 proportions and biochemical parameters were measured. Pearson correlation test and logistic regression analysis were used to examine correlation and odds ratio (OR). 144 HD patients completed one-year follow-up. Cohort with macrovascular events revealed significantly lower HDL-2b and higher HDL-3 subclass proportions compared to those without events. By multivariable adjustment, HDL-3 subclass proportion revealed significantly increase risk for these events (OR 1.17, 95% CI 1.02-1.41, P = 0.044). HDL-2b subclass was significantly higher and HDL-3 subclass was significantly lower in the HD cohort under the hs-CRP level of < 3 mg/L compared to higher hs-CRP level. In conclusion, HDL-2b and HDL-3 subclasses distributions were associated with macrovascular events in HD patients. Proinflammatory status influences the distribution of HDL-2b and HDL-3 subclasses in HD patients.

A homogeneous assay to determine high-density lipoprotein subclass cholesterol in serum.

Existing methods to measure high-density lipoprotein cholesterol (HDL-C) subclasses (HDL2-C and HDL3-C) are complex and require proficiency, and thus there is a need for a convenient, homogeneous assay to determine HDL-C subclasses in serum. Here, cholesterol reactivities in lipoprotein fractions [HDL2, HDL3, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL)] toward polyethylene glycol (PEG)-modified enzymes were determined in the presence of varying concentrations of dextran sulfate and magnesium nitrate. Particle sizes formed in the lipoprotein fractions were measured by dynamic light scattering. We optimized the concentrations of dextran sulfate and magnesium nitrate before assay with PEG-modified enzymes to provide selectivity for HDL3-C. On addition of dextran sulfate and magnesium nitrate, the sizes of particles of HDL2, LDL, and VLDL increased, but the size of HDL3 fraction particles remained constant, allowing only HDL3-C to participate in coupled reactions with the PEG-modified enzymes. In serum from both healthy volunteers and patients with type 2 diabetes, a good correlation was observed between the proposed assay and ultracentrifugation in the determination of HDL-C subclasses. The assay proposed here enables convenient and accurate determination of HDL-C subclasses in serum on a general automatic analyzer and enables low-cost routine diagnosis without preprocessing.

Clinical-epidemiological analysis of HDL2 and HDL3 subfractions in adults from Maracaibo city, Venezuela. / Análisis clínico-epidemiológico de las subfracciones HDL2 y HDL3 en adultos de la ciudad de Maracaibo, Venezuela.

OBJECTIVE: To carry out a clinical-epidemiological analysis of high-density lipoprotein cholesterol subfractions (HDL-C) in adults from Maracaibo, Venezuela. MATERIALS AND METHODS: A descriptive and cross-sectional study of the database from the Metbolic Syndrome Prevalence in Maracaibo Study was carried out. HDL3 and HDL2 serum concentration, as well as the HDL2/HDL3 ratio, were determined in 359 individuals of both sexes, over 18 years of age. Values obtained were evaluated according to sociodemographic, clinical and biochemical characteristics. RESULTS: Mean population age was 39.4 ± 15.2 years, and 51.5% were female. Differences in HDL-C subfraction levels were only observed in those subjects with low HDL-C levels. Women with hypertriglyceridemia showed significantly lower serum HDL3 and HDL2 concentrations than those with normal triglycerides (p=0.033), as well as a lower HDL3 level and HDL2 / HDL3 ratio in those with higher levels of ultra-sensitive C-reactive protein (us-CRP) (p<0.001). A significantly lower concentration of HDL2 was observed in men with some degree of hypertension (p=0.031), insulin resistance (p=0.050) and metabolic syndrome (p=0.003); while those with elevated us-CRP showed a lower concentration of HDL3 (p=0.011). CONCLUSION: HDL-C subfractions show varying clinical-epidemiological behavior in adults from Maracaibo. Lower serum levels are observed in men, differences only in those with low HDL-C; and no predominance of any subclass was observed according to sociodemographic, clinical and biochemical characteristics.

OBJETIVO: Realizar un análisis clínico-epidemiológico de las subfracciones de colesterol unido a lipoproteinas de alta densidad (HDL-C, por sus siglas en inglés) en adultos de la ciudad de Maracaibo, Venezuela. MATERIALES Y MÉTODOS: Se realizó un estudio descriptivo y transversal de la base de datos del Estudio de Prevalencia de Síndrome Metabólico de Maracaibo, que incluyó 359 individuos de ambos sexos, mayores de 18 años, a quienes se les determinó la concentración sérica de HDL3 y HDL2, así como el índice HDL2/HDL3; evaluando sus niveles según características sociodemográficas, clínicas y bioquímicas. RESULTADOS: La edad promedio de la población era 39,4 ± 15,2 años, y 51,5% era de sexo femenino. Solo se observaron diferencias en los niveles de HDL-C en aquellos sujetos con HDL-C bajas. Las mujeres con hipertriacilgliceridemia mostraron concentraciones séricas de HDL3 y HDL2 significativamente menores con respecto a aquellas con triacilglicéridos normales (p = 0,033); asimismo, se encontró una concentración menor de HDL3 y relación HDL2/HDL3 en aquellas con proteína C reactiva ultrasensible (PCR-us) elevada (p < 0,001). En hombres, se evidenció una concentración significativamente menor de HDL2 en aquellos con algún grado de hipertensión arterial (p = 0,031), insulinorresistencia (p = 0,050) y síndrome metabólico (p = 0,003); mientras que aquellos con PCR-us elevada mostraron una menor concentración de HDL3 (p = 0,011). CONCLUSIÓN: Las subfracciones de HDL-C muestran un comportamiento clínico epidemiológico variable en adultos de la población de Maracaibo, con promedios más bajos en los hombres, diferencias en los niveles únicamente en aquellos con HDL-C bajas, y sin predominio de alguna subclase según las características sociodemográficas, clínicas y bioquímicas.

Análisis clínico-epidemiológico de las subfracciones HDL2 y HDL3 en adultos de la ciudad de Maracaibo, Venezuela / Clinical-epidemiological analysis of HDL2 and HDL3 subfractions in adults from Maracaibo city, Venezuela

RESUMEN Objetivo: Realizar un análisis clínico-epidemiológico de las subfracciones de colesterol unido a lipoproteinas de alta densidad (HDL-C, por sus siglas en inglés) en adultos de la ciudad de Maracaibo, Venezuela. Materiales y métodos: Se realizó un estudio descriptivo y transversal de la base de datos del Estudio de Prevalencia de Síndrome Metabólico de Maracaibo, que incluyó 359 individuos de ambos sexos, mayores de 18 años, a quienes se les determinó la concentración sérica de HDL3 y HDL2, así como el índice HDL2/HDL3; evaluando sus niveles según características sociodemográficas, clínicas y bioquímicas. Resultados: La edad promedio de la población era 39,4 ± 15,2 años, y 51,5% era de sexo femenino. Solo se observaron diferencias en los niveles de HDL-C en aquellos sujetos con HDL-C bajas. Las mujeres con hipertriacilgliceridemia mostraron concentraciones séricas de HDL3 y HDL2 significativamente menores con respecto a aquellas con triacilglicéridos normales (p=0,033); asimismo, se encontró una concentración menor de HDL3 y relación HDL2/HDL3 en aquellas con proteína C reactiva ultrasensible (PCR-us) elevada (p<0,001). En hombres, se evidenció una concentración significativamente menor de HDL2 en aquellos con algún grado de hipertensión arterial (p=0,031), insulinorresistencia (p=0,050) y síndrome metabólico (p=0,003); mientras que aquellos con PCR-us elevada mostraron una menor concentración de HDL3 (p=0,011). Conclusión: Las subfracciones de HDL-C muestran un comportamiento clínico epidemiológico variable en adultos de la población de Maracaibo, con promedios más bajos en los hombres, diferencias en los niveles únicamente en aquellos con HDL-C bajas, y sin predominio de alguna subclase según las características sociodemográficas, clínicas y bioquímicas.

ABSTRACT Objective: To carry out a clinical-epidemiological analysis of high-density lipoprotein cholesterol subfractions (HDL-C) in adults from Maracaibo, Venezuela. Materials and methods: A descriptive and cross-sectional study of the database from the Metbolic Syndrome Prevalence in Maracaibo Study was carried out. HDL3 and HDL2 serum concentration, as well as the HDL2/HDL3 ratio, were determined in 359 individuals of both sexes, over 18 years of age. Values obtained were evaluated according to sociodemographic, clinical and biochemical characteristics. Results: Mean population age was 39.4 ± 15.2 years, and 51.5% were female. Differences in HDL-C subfraction levels were only observed in those subjects with low HDL-C levels. Women with hypertriglyceridemia showed significantly lower serum HDL3 and HDL2 concentrations than those with normal triglycerides (p=0.033), as well as a lower HDL3 level and HDL2 / HDL3 ratio in those with higher levels of ultra-sensitive C-reactive protein (us-CRP) (p<0.001). A significantly lower concentration of HDL2 was observed in men with some degree of hypertension (p=0.031), insulin resistance (p=0.050) and metabolic syndrome (p=0.003); while those with elevated us-CRP showed a lower concentration of HDL3 (p=0.011). Conclusion: HDL-C subfractions show varying clinical-epidemiological behavior in adults from Maracaibo. Lower serum levels are observed in men, differences only in those with low HDL-C; and no predominance of any subclass was observed according to sociodemographic, clinical and biochemical characteristics.

ABCA1/ApoE/HDL Signaling Pathway Facilitates Myelination and Oligodendrogenesis after Stroke.

ATP-binding cassette transporter A1 (ABCA1) plays an important role in the regulation of apolipoprotein E (ApoE) and the biogenesis of high-density lipoprotein (HDL) cholesterol in the mammalian brain. Cholesterol is a major source for myelination. Here, we investigate whether ABCA1/ApoE/HDL contribute to myelin repair and oligodendrogenesis in the ischemic brain after stroke. Specific brain ABCA1-deficient (ABCA1-B/-B) and ABCA1-floxed (ABCA1fl/fl) control mice were subjected to permanent distal middle-cerebral-artery occlusion (dMCAo) and were intracerebrally administered (1) artificial mouse cerebrospinal fluid (CSF) as vehicle control, (2) human plasma HDL3, and (3) recombined human ApoE2 starting 24 h after dMCAo for 14 days. All stroke mice were sacrificed 21 days after dMCAo. The ABCA1-B/-B-dMCAo mice exhibit significantly reduced myelination and oligodendrogenesis in the ischemic brain as well as decreased functional outcome 21 days after stroke compared with ABCA1fl/fl mice; administration of human ApoE2 or HDL3 in the ischemic brain significantly attenuates the deficits in myelination and oligodendrogenesis in ABCA1-B/-B-dMCAo mice ( p < 0.05, n = 9/group). In vitro, ABCA1-B/-B reduces ApoE expression and decreases primary oligodendrocyte progenitor cell (OPC) migration and oligodendrocyte maturation; HDL3 and ApoE2 treatment significantly reverses ABCA1-B/-B-induced reduction in OPC migration and oligodendrocyte maturation. Our data indicate that the ABCA1/ApoE/HDL signaling pathway contributes to myelination and oligodendrogenesis in the ischemic brain after stroke.

HDL-related biomarkers are robust predictors of survival in patients with chronic liver failure.

BACKGROUND & AIMS: High-density lipoprotein cholesterol (HDL-C) levels are reduced in patients with chronic liver disease and inversely correlate with disease severity. During acute conditions such as sepsis, HDL-C levels decrease rapidly and HDL particles undergo profound changes in their composition and function. We aimed to determine whether indices of HDL quantity and quality associate with progression and survival in patients with advanced liver disease. METHODS: HDL-related biomarkers were studied in 508 patients with compensated or decompensated cirrhosis (including acute-on-chronic liver failure [ACLF]) and 40 age- and gender-matched controls. Specifically, we studied levels of HDL-C, its subclasses HDL2-C and HDL3-C, and apolipoprotein A1 (apoA-I), as well as HDL cholesterol efflux capacity as a metric of HDL functionality. RESULTS: Baseline levels of HDL-C and apoA-I were significantly lower in patients with stable cirrhosis compared to controls and were further decreased in patients with acute decompensation (AD) and ACLF. In stable cirrhosis (n = 228), both HDL-C and apoA-I predicted the development of liver-related complications independently of model for end-stage liver disease (MELD) score. In patients with AD, with or without ACLF (n = 280), both HDL-C and apoA-I were MELD-independent predictors of 90-day mortality. On ROC analysis, both HDL-C and apoA-I had high diagnostic accuracy for 90-day mortality in patients with AD (AUROCs of 0.79 and 0.80, respectively, similar to that of MELD 0.81). On Kaplan-Meier analysis, HDL-C <17 mg/dl and apoA-I <50 mg/dl indicated poor short-term survival. The prognostic accuracy of HDL-C was validated in a large external validation cohort of 985 patients with portal hypertension due to advanced chronic liver disease (AUROCs HDL-C: 0.81 vs. MELD: 0.77). CONCLUSION: HDL-related biomarkers are robust predictors of disease progression and survival in chronic liver failure. LAY SUMMARY: People who suffer from cirrhosis (scarring of the liver) have low levels of cholesterol carried by high-density lipoproteins (HDL-C). These alterations are connected to inflammation, which is a problem in severe liver disease. Herein, we show that reduced levels of HDL-C and apolipoprotein A-I (apoA-I, the main protein carried by HDL) are closely linked to the severity of liver failure, its complications and survival. Both HDL-C and apoA-I can be easily measured in clinical laboratories and are as good as currently used prognostic scores calculated from several laboratory values by complex formulas.

Cross-linking modifications of HDL apoproteins by oxidized phospholipids: structural characterization, in vivo detection, and functional implications.

Apolipoprotein A-I (apoA-I) is cross-linked and dysfunctional in human atheroma. Although multiple mechanisms of apoA-I cross-linking have been demonstrated in vitro, the in vivo mechanisms of cross-linking are not well-established. We have recently demonstrated the highly selective and efficient modification of high-density lipoprotein (HDL) apoproteins by endogenous oxidized phospholipids (oxPLs), including γ-ketoalkenal phospholipids. In the current study, we report that γ-ketoalkenal phospholipids effectively cross-link apoproteins in HDL. We further demonstrate that cross-linking impairs the cholesterol efflux mediated by apoA-I or HDL3 in vitro and in vivo Using LC-MS/MS analysis, we analyzed the pattern of apoprotein cross-linking in isolated human HDL either by synthetic γ-ketoalkenal phospholipids or by oxPLs generated during HDL oxidation in plasma by the physiologically relevant MPO-H2O2-NO2- system. We found that five histidine residues in helices 5-8 of apoA-I are preferably cross-linked by oxPLs, forming stable pyrrole adducts with lysine residues in the helices 3-4 of another apoA-I or in the central domain of apoA-II. We also identified cross-links of apoA-I and apoA-II with two minor HDL apoproteins, apoA-IV and apoE. We detected a similar pattern of apoprotein cross-linking in oxidized murine HDL. We further detected oxPL cross-link adducts of HDL apoproteins in plasma and aorta of hyperlipidemic LDLR-/- mice, including cross-link adducts of apoA-I His-165-apoA-I Lys-93, apoA-I His-154-apoA-I Lys-105, apoA-I His-154-apoA-IV Lys-149, and apoA-II Lys-30-apoE His-227. These findings suggest an important mechanism that contributes to the loss of HDL's atheroprotective function in vivo.

Comparing Data-Independent Acquisition and Parallel Reaction Monitoring in Their Abilities To Differentiate High-Density Lipoprotein Subclasses.

High-density lipoprotein (HDL) is a diverse group of particles with multiple cardioprotective functions. HDL proteome follows HDL particle complexity. Many proteins were described in HDL, but consistent quantification of HDL protein cargo is still a challenge. To address this issue, the aim of this work was to compare data-independent acquisition (DIA) and parallel reaction monitoring (PRM) methodologies in their abilities to differentiate HDL subclasses through their proteomes. To this end, we first evaluated the analytical performances of DIA and PRM using labeled peptides in pooled digested HDL as a biological matrix. Next, we compared the quantification capabilities of the two methodologies for 24 proteins found in HDL2 and HDL3 from 19 apparently healthy subjects. DIA and PRM exhibited comparable linearity, accuracy, and precision. Moreover, both methodologies worked equally well, differentiating HDL subclasses' proteomes with high precision. Our findings may help to understand HDL functional diversity.

ApoC-III Glycoforms Are Differentially Cleared by Hepatic TRL (Triglyceride-Rich Lipoprotein) Receptors.

OBJECTIVE: ApoC-III (apolipoprotein C-III) glycosylation can predict cardiovascular disease risk. Higher abundance of disialylated (apoC-III2) over monosialylated (apoC-III1) glycoforms is associated with lower plasma triglyceride levels. Yet, it remains unclear whether apoC-III glycosylation impacts TRL (triglyceride-rich lipoprotein) clearance and whether apoC-III antisense therapy (volanesorsen) affects distribution of apoC-III glycoforms. Approach and Results: To measure the abundance of human apoC-III glycoforms in plasma over time, human TRLs were injected into wild-type mice and mice lacking hepatic TRL clearance receptors, namely HSPGs (heparan sulfate proteoglycans) or both LDLR (low-density lipoprotein receptor) and LRP1 (LDLR-related protein 1). ApoC-III was more rapidly cleared in the absence of HSPG (t1/2=25.4 minutes) than in wild-type animals (t1/2=55.1 minutes). In contrast, deficiency of LDLR and LRP1 (t1/2=56.1 minutes) did not affect clearance of apoC-III. After injection, a significant increase in the relative abundance of apoC-III2 was observed in HSPG-deficient mice, whereas the opposite was observed in mice lacking LDLR and LRP1. In patients, abundance of plasma apoC-III glycoforms was assessed after placebo or volanesorsen administration. Volanesorsen treatment correlated with a statistically significant 1.4-fold increase in the relative abundance of apoC-III2 and a 15% decrease in that of apoC-III1. The decrease in relative apoC-III1 abundance was strongly correlated with decreased plasma triglyceride levels in patients. CONCLUSIONS: Our results indicate that HSPGs preferentially clear apoC-III2. In contrast, apoC-III1 is more effectively cleared by LDLR/LRP1. Clinically, the increase in the apoC-III2/apoC-III1 ratio on antisense lowering of apoC-III might reflect faster clearance of apoC-III1 because this metabolic shift associates with improved triglyceride levels.

HDL3-C is a Marker of Coronary Artery Disease Severity and Inflammation in Patients on Statin Therapy.

INTRODUCTION: Low high-density lipoprotein (HDL-C) and inflammation are risk factors for coronary artery disease (CAD). However, limited data are available determining the role of HDL-C sub-particles HDL2-C and HDL3-C for assessing CAD severity in patients on statin therapy. METHODS: Blood samples were obtained prior to cardiac catheterization in 304 consecutive patients with suspected CAD on statin therapy in this sub-analysis of Multi-Analyte, thrombogenic, and Genetic Markers of Atherosclerosis (MAGMA, NCT01276678) study. Detailed lipid profiling and oxidized LDL (ox-LDL) were analyzed. CAD severity was angiographically defined as severe CAD (>75% luminal diameter stenosis [LDS]) and non-severe CAD (≤75% LDS). Multi-regression analysis was performed to test for statistical significance. Receiver operator curve (ROC) analysis was performed to determine cut-point for predicting severe CAD. RESULTS: Patients with severe CAD had a significantly lower total-HDL-C, lower HDL3-C and higher lipoprotein(a) levels. HDL3-C and lipoprotein(a) cholesterol [Lp(a)-C] retained statistical significance on multiple regression analysis. ROC analysis showed HDL3-C to have a C-statistic of 0.60 (p = 0.003) and Lp(a)-C to have a C-statistic of 0.61 (p = 0.0007). Patients with HDL3-C ≤ 33 mg/dL and Lp(a)-C > 7 mg/dL were found to have significantly elevated ox-LDL levels. CONCLUSION: In patients on statin therapy, HDL3-C and Lp(a)-C improve prediction of severe CAD compared to a traditional lipid panel. In addition, patients with HDL3-C ≤ 33 mg/dL and Lp(a)-C > 7 mg/dL have greater inflammation marked by ox-LDL. Further studies are needed to evaluate the utility of these novel biomarkers in predicting CAD severity.

Higher High Density Lipoprotein 2 (HDL2) to Total HDL Cholesterol Ratio Is Associated with a Lower Risk for Incident Hypertension

BACKGROUND: Recent studies have suggested that high density lipoprotein (HDL) cholesterol is inversely associated with the development of hypertension. We aimed to determine the association between different HDL cholesterol subclasses and risk of future hypertension. METHODS: A total of 270 Japanese Americans (130 men, 140 women) without hypertension between the ages of 34 to 75 years were enrolled. Blood pressure was measured with a mercury sphygmomanometer, and average blood pressure was calculated. Incident hypertension was determined 5 to 6 and 10 to 11 years after enrollment. HDL2, HDL3, and total HDL cholesterol were measured at baseline. RESULTS: During 10 years of follow-up, the cumulative incidence of hypertension was 28.1% (76/270). In univariate analysis, age, diabetes, waist circumference, systolic and diastolic blood pressure, fasting glucose, insulin resistance index, total and low density lipoprotein cholesterol, and visceral adipose tissue were significant predictors for incident hypertension. Among the HDL cholesterol subclass, HDL2 cholesterol was inversely associated with hypertension incidence, but both total and HDL3 cholesterol were not. In addition, HDL2/HDL cholesterol was inversely associated with future hypertension risk. In multivariate analysis, age (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.26 to 2.31; P=0.001), systolic blood pressure (OR, 1.83; 95% CI, 1.31 to 2.56; P < 0.001), and HDL2/HDL cholesterol (OR, 0.71; 95% CI, 0.52 to 0.98; P=0.035), were associated with future development of hypertension. CONCLUSION: A higher proportion of HDL2 cholesterol among total HDL cholesterol predicted a lower risk for incident hypertension. However, concentrations of total HDL, HDL2, and HDL3 cholesterol were not independent predictors of incident hypertension.

Apolipoprotein E3-mediated cellular uptake of reconstituted high-density lipoprotein bearing core 3, 10, or 17 nm hydrophobic gold nanoparticles.

We have developed a high-density lipoprotein (HDL)-based platform for transport and delivery of hydrophobic gold nanoparticles (AuNPs). The ability of apolipoprotein E3 (apoE3) to act as a high-affinity ligand for the low-density lipoprotein receptor (LDLr) was exploited to gain entry of HDL with AuNPs into glioblastoma cells. AuNPs of 3, 10, and 17 nm diameter, the latter two synthesized by phase transfer process, were solubilized by integration with phospholipids and apoE3, yielding reconstituted HDL (rHDL) bearing AuNPs. Ultraviolet-visible spectra of rHDL-AuNP indicated the presence of stable particles with surface plasmon band at ~530 nm. Transmission electron microscopy (TEM) of rHDL-AuNP revealed roughly spherical particles with AuNPs embedded in the core. The rHDL-AuNP particles displayed robust binding to the LDLr and were internalized by receptor-mediated endocytosis in glioblastoma cells. Confocal microscopy confirmed cellular uptake of AuNPs in the endosomal-lysosomal compartments, while TEM revealed intracellular aggregated AuNPs. Cell viability assay demonstrated that >85% of cells were viable with rHDL-AuNP treatment of 0.1-100 µg/mL for 24 hours. These findings are significant since they offer an effective means of delivering AuNPs across the cell membrane, which is particularly relevant in tumor cells that overexpress LDLr.