Regular Practice of Physical Activity Improves Cholesterol Transfers to High-Density Lipoprotein (HDL) and Other HDL Metabolic Parameters in Older Adults

The effects of regular physical activity on two important anti-atherosclerosis functions of high-density lipoprotein (HDL), namely its capacity to receive both forms of cholesterol and its anti-oxidant function, were investigated in this study comparing older adults with young individuals. One-hundred and eight healthy adult individuals were enrolled and separated into the following groups: active older (60-80 yrs, n = 24); inactive older (60-79 yrs, n = 21); active young (20-34 yrs, n = 39); and inactive young (20-35 yrs, n = 24). All performed cardiopulmonary tests. Blood samples were collected in order to assess the following measures: lipid profile, HDL anti-oxidant capacity, paraoxonase-1 activity, HDL subfractions, and lipid transfer to HDL. Comparing active older and active young groups with inactive older and inactive young groups, respectively, the active groups presented higher HDL-C levels (p < 0.01 for both comparisons), unesterified cholesterol transfer (p < 0.01, p < 0.05), and intermediate and larger HDL subfractions (p < 0.001, p < 0.01) than the respective inactive groups. In addition, the active young group showed higher esterified cholesterol transfer than the inactive young group (p < 0.05). As expected, the two active groups had higher VO2peak than the inactive groups; VO2peak was higher in the two younger than in the two older groups (p < 0.05). No differences in unesterified and esterified cholesterol transfers and HDL subfractions were found between active young and active older groups. HDL anti-oxidant capacity and paraoxonase-1 activity were equal in all four study groups. Our data highlight and strengthen the benefits of regular practice of physical activity on an important HDL function, the capacity of HDL to receive cholesterol, despite the age-dependent decrease in VO2peak.

Effect of exercise training on HDL subclasses and cholesterol transfers to HDL in elderly individuals

Introduction

Lifestyle habits play a crucial role on coronary artery disease (CAD) prevention. Exercise training promotes increase of HDL-C and decrease of plasma triglycerides is an important tool against atherogenesis. HDL-C determination evaluates only partially the HDL status and anti-atherosclerotic potential. A number of other parameters also relates HDL metabolism and function with CAD, such as HDL subclass distribution and cholesterol transfer to HDL, that have been reported as impaired in CAD. It is known that exercise training can improve those parameters in young individuals, but it has not been explored whether this effect can also be obtained in elderly subjects undergoing moderate training.

Purpose

Investigate the effects of regular practice of moderate exercise training on cholesterol transfer to HDL and HDL subclasses distribution in elderly compared to young subjects.

Methods

111 healthy subjects were enrolled in this study, as divided in four groups paired by sex: active elderly (AE, n=25), inactive elderly (IE, n=21), active young (AY, n=40) and inactive young (IY, n=25). All subjects performed cardiopulmonary test to determine VO2 peak and answered a questionnaire about exercise practice; only subjects practicing regular training for at least one year were selected to the 2 “active” groups. Blood samples were collected to determine lipid and apolipoprotein profile. Lipid subfractions were measured using the Lipoprint system. Cholesterol transfer to HDL was performed by incubating plasma with a donor lipoprotein-like nanoparticle containing radioactively labeled unesterified (UC) and esterified cholesterol (EC), followed by chemical precipitation and radioactive count.

Results

Data are shown on Table 1. Higher VO2 peak in both active groups confirmed the effectiveness of the training. HDL-C was higher in AE and AY than in IE and IY; apo A-I was higher in AY than in IY, but AE and IE were equal. UC transfer was higher in AE and AY than in IE and IY, but EC was higher AY than in IY, AE and IE were equal. Large HDL subfraction was higher in AY than in IY, but AE and IE were equal. The intermediate HDL subfraction was higher in AE than in IE. Comparing AE with AY, no differences in UC and EC, as well as HDL subfractions were observed.

Conclusion

Training had the ability to improve parameters of HDL metabolism not only in young but also in elderly subjects and it is remarkable that, despite their lower VO2 peak, in the AE group the cholesterol transfers and the HDL subfraction profile were similar to those of the AY group. Those results confirm the effectiveness of training to improve HDL anti-atherosclerotic features in the elderly.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Fundação de Amparo à Pesquisa do Estado de São Paulo

Lipid transfer to high-density lipoprotein is greater in elderly individuals with higher predictive cardiorespiratory fitness for age

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): FAPESP and CNPq

Background

Elderly individuals have higher coronary artery disease (CAD) risk. Triggering factors include diminished peak of oxygen consumption (VO2peak), commonly referred as cardiorespiratory fitness (CF), and increase in atherogenic lipid profile: non high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). The effect of aging on HDL-C is yet not clear, however, evaluating only the concentrations do not represent all HDL anti-atherosclerosis potential, aspects related to HDL metabolism and function can be more accurate to understand atherosclerosis process. Beyond that, elderly individuals also show reduced lipid transfer to HDL, an important assessment of HDL metabolism and function reported to be lower in CAD patients. Additionally, higher CF level is associated with longevity and lower hospitalizations rates and higher lipid transfer, independently of HDL-C. Data about different ages and absolute values of CF on lipids transfer are nonexistent. Purpose: To analyze the effect of paired CF absolute values and BMI in a healthy population of different ages on lipid transfer to HDL. Methods: 61 healthy individuals, enrolled in two groups: 30 young (27 ± 4 years, 21 females, BMI: 24.6 ± 2.6 kg/m², VO2peak: 33.9 ± 5.0 ml/kg/min) and 31 elderly (67 ± 5 years, 15 females, BMI: 23.9 ± 3.3 kg/m², VO2peak: 33.2 ± 4.5 ml/kg/min) that do not use any medication for chronic disease. Anthropometric data were collected. All participants performed treadmill cardiopulmonary test and the CF predictive value for age was calculated, according to each sex. Plasma lipids and cholesterol ester transfer protein (CETP) concentrations were determined. Lipid transfer was performed by incubating plasma with a donor lipoprotein-like nanoparticle containing radioactively labeled unesterified cholesterol (UC) and esterified cholesterol (EC), followed by chemical precipitation and radioactive count.  Cholesterol transfers from the donor nanoparticle to HDL are expressed as %. For the statistical analysis Student"s t and Mann-Whitney tests were used according to data distribution. Results: Waist circumference (p = 0.0291) and waist-hip ratio (p &lt; 0.0001) were higher in elderly. LDL-C (p = 0.0005) and non HDL-C (p = 0.0003) were higher in elderly, as well apolipoprotein A-I, B, and CETP concentration. HDL-C and triglycerides were equal between groups. EC (p = 0.0268) and UC (p = 0.0348) transfers to HDL were higher in elderly. VO2peak predictive by age expressed in percentage was higher in elderly (90 ± 13 vs. 120 ±18; p &lt; 0.0001). Conclusion: Elderly individuals show higher anthropometric data and concentrations of atherogenic cholesterol lipoproteins; however, HDL-C was equal. When paired by absolute CF values and BMI with young adults, elderly subjects with high CF predicted by age, have higher cholesterol transfer to HDL which demonstrates greater HDL metabolism.

Use of paclitaxel carried in lipid nanoparticles to treat aortic allograft transplantation in rats

OBJECTIVES

The aim of this study was to test whether lipid core nanoparticles loaded with paclitaxel (LDE-PTX) protect rat aortic allograft from immunological damage.

METHODS

Fisher and Lewis rats were used differing in minor histocompatibility loci. Sixteen Lewis rats were allocated to four-animal groups: SYNG (syngeneic), Lewis rats receiving aorta grafts from Lewis rats; ALLO (allogeneic), Lewis rats receiving aortas from Fisher rats; ALLO+LDE (allogeneic transplant treated with LDE), Lewis rats receiving aortas from Fisher rats, treated with LDE (weekly injection for 3 weeks); ALLO+LDE-PTX (allogeneic transplant treated with LDE-PTX), Lewis rats receiving aortas from Fisher rats treated with LDE-PTX (4 mg/kg weekly for 3 weeks). Treatments began on transplantation day.

RESULTS

Thirty days post-transplantation, SYNG showed intact aortas. ALLO and ALLO+LDE presented intense neointimal formation. In ALLO+LDE-PTX, treatment inhibited neointimal formation; narrowing of aortic lumen was prevented in ALLO and ALLO+LDE. LDE-PTX strongly inhibited proliferation and intimal invasion by smooth muscle cells, diminished 4-fold presence of apoptotic/dead cells in the intima, reduced the invasion of aorta by macrophages and T-cells and gene expression of pro-inflammatory tumour necrosis factor-alpha (TNFα), interferon gamma (IFNγ) and interleukin-1 beta (IL-1β).

CONCLUSIONS

LDE-PTX was effective in preventing the vasculopathy associated with rejection and may offer a potent therapeutic tool for post-transplantation.

Novel Approach for Bone Marrow Transplantation Conditioning in Acute Myelogenous Leukemia not Responding to the Induction Therapy Using Etoposide Carried in Lipid Core Nanoparticles: A Pilot Clinical Study

Allogeneic hematopoietic cell transplantation (HCT) is the treatment of choice for acute myelogenous leukemia (AML) not responding to induction therapy. It is a therapeutic choice for the blast phase of chronic myelogenous leukemia (CML-BP) in patients failing to respond to tyrosine kinase inhibitors (TKIs). Lipid core nanoparticles (LDEs) concentrate severalfold more in blast cells than in corresponding normal cells. Incorporation of anticancer drugs to LDE formulations increases the pharmacologic action and decreases the toxicity. We tested a drug-targeting system, LDE-etoposide plus total body irradiation (TBI; 1200 cGy dose), in 13 patients with AML not responding to the induction therapy and in 2 patients with CML-BP refractory to second-generation TKIs. The mean patient age was 46.7 years (range, 22 to 66 years). The LDE-etoposide dose was escalated at 20, 30, 40, 50, and 60 mg/kg. No patients developed grade 4 or 5 toxicity; however, mucositis grade 3 occurred in 6 patients, 3 patients experienced diarrhea, and 1 patient had an elevated total bilirubin level. No deaths were related to conditioning. All patients were successfully engrafted. The median times to neutrophil and platelet engraftment were 20 ± 5 days and 16 ± 4 days, respectively. Five patients (33.4%) had acute graft-versus-host-disease (GVHD), including 4 grade I, and 1 with grade II, and 8 patients (57.1%) had moderate-to-severe chronic GVHD. This pilot study shows the potential of LDE-etoposide plus TBI as an HCT conditioning regimen in AML patients not responding to the induction and refractory therapies for CML-BP patient. These findings pave the way for subsequent larger clinical trials.

Subclinical Hyperthyroidism: Status of the Cholesterol Transfers to HDL and Other Parameters Related to Lipoprotein Metabolism in Patients Submitted to Thyroidectomy for Thyroid Cancer

Purpose: Lipid metabolism has been poorly explored in subclinical hyperthyroidism. The aim was to examine the effects of exogenous subclinical hyperthyroidism in women under levothyroxine treatment upon plasma lipids and aspects of HDL metabolism. Methodology: Ten women were studied in euthyroidism and again in exogenous subclinical hyperthyroidism. Thyroid function tests and plasma lipids were studied. Results: HDL-cholesterol (increased 21.6%, p = 0.0004), unesterified cholesterol (increased 12.3%, p = 0.04) and Lp(a) (increased 33,3%, P = 0.02) plasma concentrations were higher in subclinical hyperthyroidism compared to euthyroidism, but total cholesterol, LDL, non-HDL cholesterol, triglycerides, apo A-I, apo B were unchanged. PON1 activity (decreased 75%, p = 0.0006) was lower in subclinical hyperthyroidism. There were no changes in HDL particle size, CETP and LCAT concentrations. The in vitro assay that estimates the lipid transfers to HDL showed that esterified cholesterol (increased 7.1%, p = 0.03), unesterified cholesterol (increased 7.8%, p = 0.02) and triglycerides (increased 6.8%, p = 0.006) transfers were higher in subclinical hyperthyroidism. There were no changes in phospholipid transfers to HDL in subclinical hyperthyroidism. Conclusions: Several alterations in the plasma lipid metabolism were observed in the subclinical hyperthyroidism state that highlight the importance of this aspect in the follow-up of those patients. The increase in HDL-C and in the transfer of unesterified and esterified cholesterol to HDL, an important anti-atherogenic HDL function are consistently protective for cardiovascular health. The increase in Lp(a) and the decrease in PON-1 activity that are important risk factors were documented here in subclinical hyperthyroidism and these results should be confirmed in larger studies due to great data variation but should not be neglected in the follow-up of those patients.

Lipid transfer to high-density lipoproteins in coronary artery disease patients with and without previous cerebrovascular ischemic events

BACKGROUND

Patients with coronary artery disease (CAD) and previous ischemic cerebrovascular events (ICVE, ischemic stroke, or transitory ischemic attack) constitute a high-risk subgroup for cardiovascular outcomes. High-density lipoprotein cholesterol (HDL-C) levels are correlated with cardiovascular events. Lipid transfer to HDL affects structure size and HDL subclass profile. Impairment of this transfer could influence ischemic risk seen in patients with CAD + ICVE. The objective was to evaluate the HDL ability to receive the lipids in patients with CAD with or without ICVE.

METHODS

Patients with CAD + ICVE (n = 60) and patients with CAD only (n = 60) were matched by age, sex, acute coronary syndromes (ACS) event type, and time elapsed between the ACS event and inclusion in the study. Lipid transfer to HDL was evaluated by incubating donor lipid nanoparticles labeled with radioactive unesterified cholesterol (UC) and esterified cholesterol (EC), phospholipid (PL), and triglyceride (TG) with whole plasma. After the chemical precipitation of non-HDL fractions and nanoparticles, the supernatant was counted for HDL radioactivity.

RESULTS

CAD + ICVE group presented with impaired lipid transfer to HDL for PL (CAD + ICVE: 21.14 ± 2.7% vs CAD: 21.67 ± 3.1%, P = .03), TG (CAD + ICVE: 4.88 ± 0.97% vs CAD: 5.63 ± 0.92%, P = .002), and UC (CAD + ICVE: 5.55 ± 1.19% vs CAD: 6.16 ± 1.14%, P = .009). Lipid transfer to HDL was similar in both groups for EC. Adjusted models showed similar results.

CONCLUSION

Patients with CAD and ICVE have reduced lipid transfer to HDL compared to those with CAD only. Dysfunctional HDL may account for the higher incidence of ischemic outcomes observed in this population.

Effects of Short-Term Hypothyroidism on the Lipid Transfer to High-Density Lipoprotein and Other Parameters Related to Lipoprotein Metabolism in Patients Submitted to Thyroidectomy for Thyroid Cancer

BACKGROUND

Elevation of low-density lipoprotein (LDL) cholesterol is the hallmark of the dyslipidemia observed in hypothyroidism, but alterations on high-density lipoprotein (HDL) plasma levels and metabolism are less understood. The aim of this study was to explore aspects of HDL metabolism and enzymes that act on HDL after a short period of overt hypothyroidism.

METHODS

Eighteen women (age 44 ± 11 years; body mass index 27.9 ± 5.2 kg/m²) were studied before total thyroidectomy for thyroid cancer, when they were euthyroid, and after thyroidectomy, in overt hypothyroidism for three weeks, following levothyroxine withdrawal for performance of a whole-body scan.

RESULTS

Thyrotropin and free thyroxine confirmed hypothyroidism; low thyroglobulin and radioiodine uptake indicated near absence of thyroid tissue. LDL cholesterol (125 ± 35 vs. 167 ± 40 mg/dL; p = 0.0002), HDL cholesterol (HDL-C; 39 ± 8 vs. 46 ± 10 mg/dL; p = 0.0025), non-HDL-C (149 ± 38 vs. 201 ± 46 mg/dL; p < 0.0001), unesterified cholesterol (53 ± 10 vs. 70 ± 16 mg/dL; p = 0.0003), apolipoprotein (apo) A-I (1.32 ± 0.19 vs. 1.44 ± 0.22 g/L; p < 0.04), and apo B (0.97 ± 0.25 vs. 1.31 ± 0.28 g/L; p < 0.0001) plasma concentrations were all higher in hypothyroidism compared to values in the euthyroid state, but triglycerides and Lp(a) were unchanged. There were no changes in HDL particle size and lipid composition, cholesteryl ester transfer protein and lecithin cholesterol acyltransferase concentrations and in paraoxonase-1 activity. Regarding the in vitro assay to estimate lipid transfer to HDL, there were no changes when comparing the euthyroid to the hypothyroid state, but when adjusted for HDL-C, the unesterified cholesterol (0.14 ± 0.03 vs. 0.11 ± 0.02; p < 0.0001), triglycerides (0.11 ± 0.02 vs. 0.09 ± 0.02; p < 0.0001), phospholipids (0.44 ± 0.09 vs. 0.40 ± 0.07; p = 0.0205), and esterified cholesterol (0.14 ± 0.03 vs. 0.13 ± 0.03; p = 0.0043) transfer to HDL were all diminished in hypothyroidism.

CONCLUSIONS

In short-term hypothyroidism, HDL-C increased, but this did not increase the capacity of the HDL fraction to receive lipids or the activity of paraoxonase-1, the anti-oxidation enzyme associated to HDL.

Obstructive sleep apnea and effects of continuous positive airway pressure on triglyceride-rich lipoprotein metabolism

This study aimed to explore lipoprotein metabolism in obstructive sleep apnea (OSA) and the effects of continuous positive airway pressure (CPAP). We studied 15 men with severe OSA [apnea-hypopnea index (AHI) ≥30 events/hour] and 12 age-, BMI-, and waist circumference-matched volunteers without OSA (AHI <5 events/hour). Carotid intima-media thickness (CIMT) was determined by a blind examiner. After 12 h fasting, a triglyceride-rich chylomicron-like emulsion, labeled with [¹⁴C]cholesteryl oleate and [³H]triolein, was injected intravenously followed by blood sample collection at preestablished times. Fractional clearance rate (FCR) of the radiolabeled lipids was estimated by compartmental analysis of radioisotope decay curves. Compared with controls, patients with OSA showed a significant delay in both cholesteryl ester FCR (0.0126 ± 0.0187 vs. 0.0015 ± 0.0025 min^-1; P = 0.0313) and triglycerides FCR (0.0334 ± 0.0390 vs. 0.0051 ± 0.0074 min^-1; P = 0.0001). CIMT was higher in the OSA group: 620 ± 17 vs. 725 ± 29 µm; P = 0.004. Cholesteryl ester FCRs were inversely related to total sleep time <90% (r = -0.463; P = 0.029) and CIMT (r = -0.601; P = 0.022). The triglyceride FCR was inversely correlated with AHI (r = -0.537; P = 0.04). In a subgroup of patients treated with CPAP for 3 months (n = 7), triglyceride FCR increased 5-fold (P = 0.025), but the cholesteryl ester FCR was unchanged. In conclusion, severe OSA decreased lipolysis of triglyceride-rich lipoproteins and delayed removal of remnants. CPAP treatment may be effective to restore the lipolysis rates.

Clinical experience with drug delivery systems as tools to decrease the toxicity of anticancer chemotherapeutic agents

INTRODUCTION

The toxicity of chemotherapeutic agents, resulting from their low pharmacological index, introduces considerable discomfort and risk to cancer patients. Among several strategies to reduce the toxicity of chemotherapeutic agents, targeted drug delivery is the most promising one. Areas covered: Liposomes, micelles, albumin-based, polymeric, dendritic and lipid core nanoparticles have been used as carriers to concentrate anticancer drugs in neoplastic tissues, and clinical studies of those preparations are reviewed. In most clinical studies, drug delivery systems reduced drug toxicity. Lipid core nanoparticles (LDE) that bind to cell lipoprotein receptors have the ability to concentrate in neoplastic tissues and were the first artificial non-liposomal system shown in in vivo studies to possess targeting properties. The toxicity reduction achieved by LDE as vehicle of carmustine, etoposide and paclitaxel was singularly strong. Expert opinion: The reduced toxicity offered by drug delivery systems has expanded treatment population that may benefit from chemotherapy including feeble, overtreated and elderly patients that would otherwise be offered palliative therapy. Drug delivery systems may either prolong the duration of treatments or allow increases in drug dose.

Evaluation of liver glycogen catabolism during hypercortisolism induced by the administration of dexamethasone in rats

BACKGROUND

The contribution of liver glycogen catabolism to hyperglycemia and glucose intolerance induced by pharmacological hypercortisolism were investigated.

METHODS

For this purpose, adult male Wistar rats that received 1.0 mg/kg dexamethasone (DEX) ip at 8:00 a.m. (DEX group) or saline (CON group) once a day for 5 consecutive days were compared.

RESULTS

Experimental hypercortisolism was confirmed by higher (p<0.05) glycemia, lower (p<0.05) body weight and glucose intolerance. In the fed state, the basal glycogen catabolism and the glucagon (1 nM) and epinephrine (2 μM) induced glycogen catabolism were similar between the groups. The activation of glycogen catabolism induced by phenylephrine (2 μM) and isoproterenol (20 μM) were increased (p<0.05) and decreased (p<0.05), respectively, in DEX rats. Furthermore, DEX rats exhibited higher (p<0.05) glycogen catabolism during the infusion of cAMP (3 μM). However, during the infusion of cAMP (15 μM), 6MB-cAMP (3 μM) or cyanide (0.5 mM), the intensification of glycogen breakdown was similar. Thus, in general, hypercortisolism does not influence the basal glycogen catabolism and the liver responsiveness to glycogenolytic agents in the fed state. In contrast with fed state, fasted rats (DEX group) showed a more intense (p<0.05) basal glycogen catabolism.

CONCLUSION

The contribution of glycogen catabolism to hyperglycemia during hypercortisolism depends of the nutritional status, starting from a negligible participation in the fed state up to a significant contribution in the fasted state.