Transfer of Cholesterol and Other Lipids From a Lipid Nanoemulsion to High-density Lipoprotein in Heart Transplant Patients

Hydroxychloroquine increased cholesterol transfer to high-density lipoprotein in systemic lupus erythematosus: A possible mechanism for the reversal of atherosclerosis in the disease

INTRODUCTION

The beneficial effect of hydroxychloroquine (HCQ) in decreasing LDL levels on Systemic Lupus Erythematosus (SLE) is well defined. The influence of this drug on HDL levels is still under debate and information about its effect on cholesterol reverse transport is lacking.

OBJECTIVE

To evaluate the effects of HCQ on HDL levels and the transfer of lipids to this lipoprotein in SLE.

METHODS

Nineteen SLE patients using only HCQ (SLE WITH HCQ), 19 SLE patients without any therapy (SLE WITHOUT THERAPY), and 19 healthy controls (CONTROL) were included. All three groups were premenopausal women age- and gender-matched. Serum lipids and apolipoproteins were determined by commercial kits. An in vitro transfer of four lipids (¹⁴C-Phospolipid, ³H-Cholesteryl ester, ³H-Triglyceride, and ¹⁴C-Unesterified cholesterol) from a radioactively labeled nanoemulsion donor to HDL was performed in all participants.

RESULTS

Groups had comparable mean age, weight, height, BMI(body mass index), and waist circumference (p > .05). Mean HDL levels were higher in SLE WITH HCQ group compared to SLE WITHOUT THERAPY(58.37 ± 14.04 vs 49.79 ± 8.0 mg/dL; p < .05) but lower than CONTROL (58.37 ± 14.04 vs 68.58 ± 9.99 mg/dL; p < .05). Total cholesterol (TC) and LDL levels were also significantly lower in SLE WITH HCQ compared SLE WITHOUT THERAPY(148.16 ± 16.43 vs 167.11 ± 30.18 mg/dL; p < .05, 75.05 ± 22.52 vs 96.05 ± 25.63 mg/dL; p < .05) and CONTROL (148.16 ± 16.43 vs 174.11 ± 23.70 mg/dL; p < .05, 75.05 ± 22.52 vs 88.53 ± 20.24 mg/dL; p < .05). The in vitro lipid transfer to HDL study revealed a significant difference among the three groups (p = .002) with a higher transfer of unesterified cholesterol(UC) in SLE WITH HCQ compared to SLE WITHOUT THERAPY(5.40 ± 1.05% vs. 4.44 ± 1.05%; p < .05). The latter was significantly decreased compared to CONTROL (5.40 ± 1.05% vs. 5.99 ± 1.71%; p < .05).The percentages of transfer of triacylglycerol (4.93 ± 0.69% vs. 4.50 ± 0.69% vs. 5.14 ± 1.01%; p = .054), esterified cholesterol (5.24 ± 0.70% vs. 4.96 ± 0.89% vs. 5.69 ± 1.27%; p = .079), and phospholipid (15.67 ± 1.03% vs. 15.34 ± 1.44% vs. 16.47 ± 1.89%; p = .066) were similar among groups.

CONCLUSION

The present study is the first to demonstrate that HCQ promoted a higher transfer of unesterified cholesterol which may account for the increased HDL levels in lupus patients under HCQ. This desirable effect may underlie the reported reduced atherosclerosis in SLE.

Androgen deprivation therapy improves the in vitro capacity of high-density lipoprotein (HDL) to receive cholesterol and other lipids in patients with prostate carcinoma

Background

Androgen deprivation therapy (ADT) is widely used in the treatment of testosterone-dependent prostate carcinomas. ADT often increases plasma LDL and HDL cholesterol and triglycerides. The aim was to test whether ADT changes the transfer of lipids to HDL, an important aspect of this metabolism and HDL protective functions, and related parameters.

Methods

Sixteen volunteers with advanced prostate carcinoma submitted to pharmacological ADT or orchiectomy had plasma collected shortly before and after 6 months of ADT. In vitro transfer of lipids to HDL was performed by incubating plasma with donor emulsion containing radioactive lipids by 1 h at 37 °C. After chemical precipitation of apolipoprotein B-containing lipoprotein, the radioactivity of HDL fraction was counted.

Results

ADT reduced testosterone to nearly undetectable levels and markedly diminished PSA. ADT increased the body weight but glycemia, triglycerides, LDL and HDL cholesterol, HDL lipid composition and CETP concentration were unchanged. However, ADT increased the plasma unesterified cholesterol concentration (48 ± 12 vs 56 ± 12 mg/dL, p = 0.019) and LCAT concentration (7.15 ± 1.81 vs 8.01 ± 1.55μg/mL, p = 0.020). Transfer of unesterified (7.32 ± 1.09 vs 8.18 ± 1.52%, p < 0.05) and esterified cholesterol (6.15 ± 0.69 vs 6.94 ± 1.29%, p < 0.01) and of triglycerides (6.37 ± 0.43 vs 7.18 ± 0.91%, p < 0.001) to HDL were increased after ADT. Phospholipid transfer was unchanged.

Conclusion

Increase in transfer of unesterified and esterified cholesterol protects against cardiovascular disease, as shown previously, and increased LCAT favors cholesterol esterification and facilitates the reverse cholesterol transport. Thus, our results suggest that ADT may offer anti-atherosclerosis protection by improving HDL functional properties. This could counteract, at least partially, the eventual worse effects on plasma lipids.

Aerobic Training in Young Men Increases the Transfer of Cholesterol to High Density Lipoprotein In Vitro: Impact of High Density Lipoprotein Size

Exercise training not only improves the plasma lipid profile but also reduces risk of developing coronary heart disease. We investigate whether plasma lipids and high density lipoprotein (HDL) metabolism are affected by aerobic training and whether the high-density lipoprotein cholesterol (HDL-C) levels at baseline influence exercise-induced changes in HDL. Seventy-one male sedentary volunteers were evaluated and allocated in two subgroups, according to the HLD-C levels (< or >40 mg/dL). Participants underwent an 18-week aerobic training period. Blood was sampled before and after training for biochemical analysis. Plasma lipids, apolipoproteins, HDL diameter, and VO₂ peak were determined. Lipid transfers to HDL were determined in vitro by incubating plasma samples with a donor lipid artificial nanoemulsion. After the 18-week period of aerobic training, the VO₂ peak increased, while the mean body mass index (BMI) decreased. HDL-C concentration was higher after the training period, but low-density lipoprotein cholesterol (LDL-C) and non-HDL-C did not change. The transfer of esterified cholesterol and phospholipids was greater after exercise training, but the triacylglycerol and unesterified cholesterol transfers were unchanged. The HDL particle diameter increased after aerobic training in all participants. When the participants were separated in low-HDL and normal-HDL groups, the postaerobic exercise increment in HDL-C was higher in the low-HDL group, while the transfer of esterified cholesterol was lower. In conclusion, aerobic exercise training increases the lipid transfers to HDL, as measured by an in vitro method, which possibly contributes to the classical elevation of the HDL-C associated with training.

Plasma kinetics of an LDL-like non-protein nanoemulsion and transfer of lipids to high-density lipoprotein (HDL) in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a systemic inflammatory disease associated with cardiovascular risk, but with normal plasma lipids.

OBJECTIVE

The aim was to investigate low-density lipoprotein (LDL) and high-density lipoprotein (HDL) metabolism in RA patients using radioactive nanoemulsions resembling an LDL lipid structure (LDE) as metabolic probes.

METHODS

Thirty patients with RA, 16 in remission and 14 in high activity, and 30 healthy controls were studied. LDE labeled with (14)C-cholesteryl ester ((14)C-CE) and (3)H-unesterified cholesterol ((3)H-UC) was intravenously injected followed by 24-hour plasma sampling. Fractional clearance rates (FCR, h(-1)) were calculated by compartmental analysis. Lipid transfers to HDL were assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids; % lipids transferred to HDL were quantified after chemical precipitation.

RESULTS

LDL cholesterol, triglycerides, unesterified cholesterol, and oxidized LDL were equal in RA and controls, and HDL cholesterol was even higher in RA. Compared with controls, apolipoprotein B was lower, apolipoprotein A1 was equal, and apolipoprotein E was higher in RA. Decay curves of LDE labels were faster in RA patients than in controls ((14)C-CE: 0.072 ± 0.066 and 0.038 ± 0.027, P = .0115; (3)H-UC: 0.066 ± 0.042 and 0.035 ± 0.039; P < .0044). FCRs were equal in 2 RA subgroups. Transfer of UC, triglycerides, and phospholipids to HDL was equal between RA and controls, but CE transfer was lower in RA. HDL size was smaller in RA patients than in controls (8.5 ± 0.5 nm; 9.2 ± 0.8 nm, P < .0001).

CONCLUSION

RA patients were more efficient in removing atherogenic LDL from plasma, as indicated by higher CE and UC FCR, with in lower apolipoprotein B. This was unexpected because of the higher cardiovascular risk in RA.

Transfer of lipids to high-density lipoprotein (HDL) is altered in patients with familial hypercholesterolemia

OBJECTIVE

In familial hypercholesterolemia (FH), the metabolism and anti-atherogenic functions of HDL can be affected by the continuous interactions with excess LDL amounts. Here, lipid transfers to HDL, an important step for HDL intravascular metabolism and for HDL role in reverse cholesterol transport (RCT) were investigated in FH patients.

METHODS

Seventy-one FH patients (39 ± 15 years, LDL-cholesterol=274 ± 101; HDL-cholesterol=50 ± 14 mg/dl) and 66 normolipidemic subjects (NL) (38 ± 11 years, LDL-cholesterol=105 ± 27; HDL-cholesterol=52 ± 12 mg/dl) were studied. In vitro, lipid transfers were evaluated by incubation of plasma samples (37°C, 1h) with a donor lipid nanoemulsion labeled with 3H-triglycerides (TG) and 14C-unesterified cholesterol (UC) or with 3H-cholesteryl ester (EC) and 14C-phospholipids (PL). Radioactivity was counted at the HDL fraction after chemical precipitation of apolipoprotein (apo) B-containing lipoproteins and the nanoemulsion. Data are % of total radioactivity measured in the HDL fraction.

RESULTS

Transfer of UC to HDL was lower in FH than in NL (5.6 ± 2.1 vs 6.7 ± 2.0%, p=0.0005) whereas TG (5.5 ± 3.1 vs 3.7 ± 0.9%, p=0.018) and PL (20.9 ± 4.6 vs 18.2 ± 3.7 %, p=0.023) transfers were higher in FH. EC transfer was equal. By multivariate analysis, transfers of all four lipids correlated with HDL-cholesterol and with apo A-I.

CONCLUSION

FH elicited marked changes in three of the four tested lipid transfers to HDL. The entry of UC into HDL for subsequent esterification is an important driving force for RCT and reduction of UC transfer to HDL was previously associated to precocious coronary heart disease. Therefore, in FH, HDL functions can be lessened, which can also contribute to atherogenesis.

Removal from the plasma of the free and esterified forms of cholesterol and transfer of lipids to HDL in type 2 diabetes mellitus patients

BACKGROUND

The aim was to investigate new markers for type 2 diabetes (T2DM) dyslipidemia related with LDL and HDL metabolism. Removal from plasma of free and esterified cholesterol transported in LDL and the transfer of lipids to HDL are important aspects of the lipoprotein intravascular metabolism. The plasma kinetics (fractional clearance rate, FCR) and transfers of lipids to HDL were explored in T2DM patients and controls, using as tool a nanoemulsion that mimics LDL lipid structure (LDE).

RESULTS

14C- cholesteryl ester FCR of the nanoemulsion was greater in T2DM than in controls (0.07 ± 0.02 vs. 0.05 ± 0.01 h-1, p = 0.02) indicating that LDE was removed faster, but FCR 3 H- cholesterol was equal in both groups. Esterification rates of LDE free-cholesterol were equal. Cholesteryl ester and triglyceride transfer from LDE to HDL was greater in T2DM (4.2 ± 0.8 vs. 3.5 ± 0.7%, p = 0.03 and 6.8 ± 1.6% vs. 5.0 ± 1.1, p = 0.03, respectively). Phospholipid and free cholesterol transfers were not different.

CONCLUSIONS

The kinetics of free and esterified cholesterol tended to be independent in T2DM patients and the lipid transfers to HDL were also disturbed. These novel findings may be related with pathophysiological mechanisms of diabetic macrovascular disease.

Lipid transfers to HDL are predictors of precocious clinical coronary heart disease

BACKGROUND

High-density-lipoprotein (HDL) has several antiatherogenic properties and, although the concentration of HDL-cholesterol negatively correlates with incidence of coronary artery disease (CAD), this is not sufficient to evaluate the overall HDL protective role. The aim was to investigate whether precocious CAD patients show abnormalities in lipid transfers to HDL, a fundamental step in HDL metabolism and function.

METHODS

Thirty normocholesterolemic CAD patients aged <50 y and 30 controls paired for sex, age and B.M.I. were studied. Fasting blood samples were collected for the in vitro lipid transfer assay and plasma lipid determination. A donor nanoemulsion labeled with radioactive free-cholesterol, cholesteryl esters, phospholipids and triglycerides was incubated with whole plasma and after chemical precipitation of non-HDL fractions, supernatant was counted for radioactivity in HDL.

RESULTS

LDL and HDL-cholesterol and triglycerides were equal in both groups. Transfers of free-cholesterol (3.8±1.2%vs 7.0±3.3%,p<0.0001) and triglycerides (3.7±1.7%vs 4.9±1.9%, p=0.0125) were diminished in CAD patients whereas cholesteryl ester transfer increased (6.5±1.9%vs 4.8±1.8%, p=0.0008); phospholipid transfer was equal (17.8±3.5% vs 19.5±3.9%).

CONCLUSION

Alterations in the transfer of lipids to HDL may constitute a new marker for precocious CAD and relation of this metabolic alteration with HDL antiatherogenic function should be investigated in future studies.

Orange juice decreases low-density lipoprotein cholesterol in hypercholesterolemic subjects and improves lipid transfer to high-density lipoprotein in normal and hypercholesterolemic subjects

Orange juice (OJ) is regularly consumed worldwide, but its effects on plasma lipids have rarely been explored. This study hypothesized that consumption of OJ concentrate would improve lipid levels and lipid metabolism, which are important in high-density lipoprotein (HDL) function in normolipidemic (NC) and hypercholesterolemic (HCH) subjects. Fourteen HCH and 31 NC adults consumed 750 mL/day OJ concentrate (1:6 OJ/water) for 60 days. Eight control subjects did not consume OJ for 60 days. Plasma was collected before and on the last day for biochemical analysis and an in vitro assay of transfers of radioactively labeled free-cholesterol, cholesteryl esters, phospholipids, and triglycerides from lipoprotein-like nanoemulsions to HDL. Orange juice consumption decreased low-density lipoprotein cholesterol (160 ± 17 to 141 ± 26 mg/dL, P < .01) in the HCH group but not in the NC group. HDL-cholesterol and triglycerides remained unchanged in both groups. Free-cholesterol transfer to HDL increased (HCH: 4.4 ± 2 to 5.6 ± 1%, NC: 3.2 ± 2 to 6.2 ± 1%, P< .05) whereas triglyceride (HCH 4.9 ± 1 to 3.1 ± 1%, NC 4.4 ± 1 to 3.4 ± 1%, P< .05) and phospholipid (HCH 21.6 ± 2 to 18.6 ± 3%, NC 20.2 ± 2 to 18.4 ± 2%, P < .05) transfers decreased in both groups. Cholesteryl-ester transfer decreased only in HCH (3.6 ± 1 to 3.1 ± 1%, P < .05), but not in NC. In control subjects, plasma lipids and transfers were unaltered for 60 days. Thus, by decreasing atherogenic low-density lipoprotein cholesterol in HCH and increasing HDL ability to take up free cholesterol in HCH and NC, OJ may be beneficial to both groups as free-cholesterol transfer to HDL is crucial for cholesterol esterification and reverse cholesterol transport.

Ghrelin inhibits insulin resistance induced by glucotoxicity and lipotoxicity in cardiomyocyte

Ghrelin has wide effects on cardiovascular and endocrine system. The aims of this study are to investigate the direct damage effect of high glucose and high palmitate on cardiomyocyte, and to study the effect of ghrelin on insulin resistance induced by glucotoxicity/lipotoxicity in cardiomyocyte and the possible mechanism underlying the cardioprotective activities of ghrelin. The changes of [(3)H]-2-deoxy-d-glucose ((3)H-G) intake rates were detected by isotope tracer method and the gene expressions in insulin signal transduction pathway were detected by real-time PCR and Western blot assay. The (3)H-G intake rate significantly reduced in high glucose (25mmol/l) or high palmitate (0.5mmol/l) treated primary rat ventricular myocytes. After the treatment of ghrelin (10(-7)mol/l), the (3)H-G intake rate recovered to the normal level. In addition, the phosphorylation of AKT occurred in 10min and was the highest in 30min after the stimulation with ghrelin, which can be blocked by phosphoinositide 3-kinase (PI3K) inhibitor, LY2940002. Ghrelin also increased the mRNA levels of glucose transporter 4 (GLUT4), peroxisome proliferators (PPARr) and AMP activated protein kinase (AMPK) genes in insulin signal transduction pathway. These results indicate that the direct damage of high glucose and high palmitate on cardiomyocyte might be through insulin resistance (IR). Ghrelin can inhibit gluco/lipotoxicity induced insulin resistance by PI3K/AKT pathway. This may provide a clue for therapy for myocardial disease in diabetes mellitus.