Alterations in lipid transfer to High-Density Lipoprotein (HDL) and activity of paraoxonase-1 in HIV+ patients

Effect of inflammation on HDL structure and function

PURPOSE OF REVIEW

Studies have shown that chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism by which inflammation increases cardiovascular disease is likely multifactorial but changes in HDL structure and function that occur during inflammation could play a role.

RECENT FINDINGS

HDL levels decrease with inflammation and there are marked changes in HDL-associated proteins. Serum amyloid A markedly increases whereas apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, paraoxonase 1, and apolipoprotein M decrease. The exact mechanism by which inflammation decreases HDL levels is not defined but decreases in apolipoprotein A-I production, increases in serum amyloid A, increases in endothelial lipase and secretory phospholipase A2 activity, and decreases in lecithin:cholesterol acyltransferase activity could all contribute. The changes in HDL induced by inflammation reduce the ability of HDL to participate in reverse cholesterol transport and protect LDL from oxidation.

SUMMARY

During inflammation multiple changes in HDL structure occur leading to alterations in HDL function. In the short term, these changes may be beneficial resulting in an increase in cholesterol in peripheral cells to improve host defense and repair but over the long term these changes may increase the risk of atherosclerosis.

HIV infection induces structural and functional changes in high density lipoproteins

BACKGROUND AND AIMS

Coronary artery disease is a growing clinical problem in HIV-infected subjects. The increased risk of coronary events in this population has been linked to low levels of HDL, but the effects of HIV infection and anti-retroviral treatment (ART) on HDL structure and function remain unknown. Here, we aimed to determine the composition and function of HDL particles isolated from ART-naive and ART-positive HIV-infected patients.

METHODS AND RESULTS

Proteomic profiling revealed decreased levels of paraoxonase (PON) 1 and PON 3 in HDL from HIV patients relative to HDL from uninfected controls (p < 0.0001), and PON activity of HDL from control group (0.13 ± 0.01 U/μl) was significantly higher than PON activity of HDL from HIV-infected untreated subjects (0.12 ± 0.01 U/μl, p = 0.0035), subjects treated with non-nucleoside reverse transcriptase inhibitor (NNRTI)-based therapy (0.11 ± 0.01 U/μl, p < 0.0001), subjects treated with protease inhibitor (PI)-based therapy with detectable viral load (0.11 ± 0.01 U/μl, p < 0.0001), and PI-treated patients with undetectable viral load (0.12 ± 0.01 U/μl, p = 0.0164). Lipidomic profiling uncovered a negative correlation between CD4 T cell counts and particle sphingomyelin, lyso-phosphatidylcholine and ether-linked phosphatidylserine content in the ART-naive (R(2) = 0.2611, p < 0.05; R(2) = 0.2722, p < 0.05; and R(2) = 0.3977, p < 0.05, respectively) but not treated HIV-infected subjects. Functional analysis demonstrated a negative correlation between cholesterol efflux capacity of HDL and viral load in the ART-naive HIV-infected group (R(2) = 0.26, p = 0.026).

CONCLUSIONS

Taken together, these results indicate that HIV infection associates with a number of both protein and lipid compositional changes in HDL particles. Moreover, HIV infection affects cholesterol efflux function of HDL, thus contributing to an increased risk of atherosclerosis in this patient population.

Effect of exercise training on plasma levels and functional properties of high-density lipoprotein cholesterol in the metabolic syndrome

Intense lifestyle modifications can change the high-density lipoprotein (HDL) cholesterol concentration. The aim of the present study was to analyze the early effects of short-term exercise training, without any specific diet, on the HDL cholesterol plasma levels and HDL functional characteristics in patients with the metabolic syndrome (MS). We studied 30 sedentary subjects, 20 with and 10 without the MS. The patients with the MS underwent moderate intensity exercise training for 3 months on bicycle ergometers. Blood was sampled before and after training for biochemical analysis, paraoxonase-1 activity, and HDL subfraction composition and antioxidative capacity. Lipid transfer to HDL was assayed in vitro using a labeled nanoemulsion as the lipid donor. At baseline, the MS group had greater triglyceride levels and a lower HDL cholesterol concentration and lower paraoxonase-1 activity than did the controls. Training decreased the plasma triglycerides but did not change the low-density lipoprotein or HDL cholesterol levels. Nonetheless, exercise training increased the HDL subfractions' antioxidative capacity and paraoxonase-1 activity. After training, the MS group had compositional changes in the smallest HDL subfractions associated with increased free cholesterol and cholesterol ester transfers to HDL, reaching normal values. In conclusion, the present investigation has added relevant information about the dissociation between the quantitative and qualitative aspects of HDL after short-term exercise training without any specific diet in those with the MS, highlighting the importance of evaluating the functional aspects of the lipoproteins, in addition to their plasma levels.

Nutritional status and lipid profile of HIV-positive children and adolescents using antiretroviral therapy

OBJECTIVE

To describe nutritional status, body composition and lipid profile in children and adolescents receiving protease inhibitors.

METHODS

Fifty-nine patients, 23 treated with protease inhibitors (group 1) and 36 not using protease inhibitors (group 2). Their dietary intake, anthropometry, bioimpedance analysis and lipid profile variables were measured.

RESULTS

There was no difference in nutritional status or body composition between groups at the beginning of the study. After 6 months of follow-up, there was an increase in weight and height in both groups, as well as in waist circumference and subscapular skinfold thickness. In group 2, body mass index and triceps skinfold thickness adequacy were significantly higher after 6 months of follow-up. The groups had similar energy and macronutrient intake at any time point. After 6 months, group 1 had a higher cholesterol intake and group 2 had a higher fiber intake. Triglyceride serum levels were significantly different between the groups, with higher values in G1, at any time point [G1: 153 mg/dl (30-344); 138 (58-378) versus G2: 76 mg/dl (29-378); 76 (29-378)]. After 6 months of follow-up, G1 had higher LDL-cholesterol than G2 [104 mg/dl (40-142) versus 82 (42-145)].

CONCLUSION

The use of protease inhibitors, per se, does not seem to significantly interfere with anthropometric measures, body composition and food intake of HIV-infected children and adolescents. However, this antiretroviral therapy was associated with a significant increase in triglyceride and LDL-cholesterol in our subjects.