Antiretroviral therapy with or without protease inhibitors impairs postprandial TAG hydrolysis in HIV-infected men

Altered relationship of plasma triglycerides to HDL cholesterol in patients with HIV/HAART-associated dyslipidemia: further evidence for a unique form of metabolic syndrome in HIV patients

INTRODUCTION

Plasma triglycerides (TG) and HDL-C are inversely related in Metabolic Syndrome (MetS), due to exchange of VLDL-TG for HDL-cholesteryl esters catalyzed by cholesteryl ester transfer protein (CETP). We investigated the relationship of TG to HDL-C in highly-active antiretroviral drug (HAART)-treated HIV patients.

METHODS

Fasting plasma TG and HDL-C levels were compared in 179 hypertriglyceridemic HIV/HAART patients and 71 HIV-negative persons (31 normotriglyceridemic (NL) and 40 hypertriglyceridemic due to type IV hyperlipidemia (HTG)). CETP mass and activity were compared in 19 NL and 87 HIV/HAART subjects.

RESULTS

Among the three groups, a plot of HDL-C vs. TG gave similar slopes but significantly different y-intercepts (9.24±0.45, 8.16±0.54, 6.70±0.65, sqrt(HDL-C) for NL, HIV and HTG respectively; P<0.001); this difference persisted after adjusting HDL-C for TG, age, BMI, gender, glucose, CD4 count, viral load and HAART strata (7.18±0.20, 6.20±0.05 and 4.55±0.15 sqrt(HDL-C) for NL, HIV and HTG, respectively, P<0.001). CETP activity was not different between NL and HIV, but CETP mass was significantly higher in HIV (1.47±0.53 compared to 0.93±0.27μg/mL, P<0.0001), hence CETP specific activity was lower in HIV (22.67±13.46 compared to 28.46±8.24nmol/μg/h, P=0.001).

CONCLUSIONS

Dyslipidemic HIV/HAART patients have a distinctive HDL-C plasma concentration adjusted for TG. The weak inverse relationship between HDL-C and TG is not explained by altered total CETP activity; it could result from a non-CETP-dependent mechanism or a decrease in CETP function due to inhibitors of CETP activity in HIV patients' plasma.

Nutrition and the HIV-associated lipodystrophy syndrome

HIV-associated lipodystrophy syndrome (HALS), comprising metabolic and morphological alterations, is a known side effect of highly active antiretroviral therapy (HAART). Evidence for the role of nutrition in the management of the systemic parameters of HALS is currently limited. In the present paper we review the current knowledge base surrounding HALS, focusing particularly on the role of nutrition in mitigating the systemic parameters of the syndrome. Reported prevalence of HALS was found to vary from 9 to 83 % due to lack of a standardised definition, as well as variations in assessment methods and in the study population used. HALS is associated with both morphological (lipoatrophy, lipohypertrophy) and metabolic (dyslipidaemia, glucose intolerance, diabetes, hypertension, endothelial dysfunction and atherosclerosis) alterations, which may occur singly or in combination, and are associated with an increased risk of CVD. HAART-induced adipocyte inflammation, oxidative stress and macrophage infiltration, as well as altered adipocyte function and mitochondrial toxicity, have been shown to be central to the development of HALS. The adipocyte, therefore, represents a plausible target for treatment. Pharmacological and surgical treatment interventions have shown effect. However, their use is associated with numerous adverse effects and complications. Targeted lifestyle interventions may provide a useful alternative for managing HALS owing to their safety and tolerability. A Mediterranean-style diet has been found to be effective in improving the systemic parameters of HALS. Furthermore, the effects of n-3 PUFA supplementation are encouraging and future randomised controlled trials investigating the beneficial effects of n-3 PUFA in HALS are justified.

Altered lipid concentrations of liver, heart and plasma but not brain in HIV-1 transgenic rats

Disturbed lipid metabolism has been reported in antiretroviral-naive HIV-1-infected patients suggesting a direct effect of the virus on lipid metabolism. To test that the HIV-1 virus alone could alter lipid concentrations, we measured these concentrations in an HIV-1 transgenic (Tg) rat model of human HIV-1 infection, which demonstrates peripheral and central pathology by 7-9 months of age. Concentrations were measured in high-energy microwaved heart, brain and liver from 7-9 month-old HIV-1 Tg and wildtype rats, and in plasma from non-microwaved rats. Plasma triglycerides and liver cholesteryl ester and total cholesterol concentrations were significantly higher in HIV-1 Tg rats than controls. Heart and plasma fatty acid concentrations reflected concentration differences in liver, which showed higher n-3 and n-6 polyunsaturated fatty acid (PUFA) concentrations in multiple lipid compartments. Fatty acid concentrations were increased or decreased in heart and liver phospholipid subfractions. Brain fatty acid concentrations differed significantly between the groups for minor fatty acids such as linoleic acid and n-3 docosapentaenoic acid. The profound changes in heart, plasma and liver lipid concentrations suggest a direct effect of chronic exposure to the HIV-1 virus on peripheral lipid (including PUFA) metabolism.

Energy expenditure in HIV infection

Energy intake recommendations for adults should be based preferably on direct measurements of total daily energy expenditure (TDEE) in corresponding populations who are maintaining healthy body weight and satisfactory physical activity levels. During adolescence, pregnancy, and lactation, energy requirements should be based on TDEE plus the additional energy required to advance these physiologic states. With illness, energy expenditure and energy intake change, but nutritional intervention is not necessarily beneficial. This article reviews data on energy expenditure in HIV infection with a focus on adults, adolescents aged ≥14 y, and pregnant and lactating women. Resting energy expenditure (REE) in adults with untreated asymptomatic HIV is ~ 10% higher than in healthy control subjects. In asymptomatic adults receiving antiretroviral therapy, REE may be similarly increased. HIV wasting and secondary infections are also associated with increased REE. In contrast, TDEE is typically normal in asymptomatic HIV and decreased in HIV wasting and secondary infection. No direct measurements of REE or TDEE are available in adolescents or in pregnant or lactating women with HIV. On the basis of current data, energy intake may need to increase by ~ 10% in adults with asymptomatic HIV to maintain body weight. In adolescents and in pregnant and lactating women with asymptomatic HIV, energy requirements should approximate recommendations for their uninfected counterparts until further data are available. In the resource-rich world, the energy expenditure changes associated with HIV are unlikely to contribute to significant weight loss. More data are needed on energy expenditure in HIV-infected populations from developing nations, where concurrent malnutrition and coinfections are common.

Hypertriglyceridemia, Metabolic Syndrome, and Cardiovascular Disease in HIV-Infected Patients: Effects of Antiretroviral Therapy and Adipose Tissue Distribution

The use of combination antiretroviral therapy (CART) in HIV-infected patients has resulted in a dramatic decline in AIDS-related mortality. However, mortality due to non-AIDS conditions, particularly cardiovascular disease (CVD) seems to increase in this population. CART has been associated with several metabolic risk factors, including insulin resistance, low HDL-cholesterol, hypertriglyceridemia and postprandial hyperlipidemia. In addition, HIV itself, as well as specific antiretroviral agents, may further increase cardiovascular risk by interfering with endothelial function. As the HIV population is aging, CVD may become an increasingly growing health problem in the future. Therefore, early diagnosis and treatment of cardiovascular risk factors is warranted in this population. This paper reviews the contribution of both, HIV infection and CART, to insulin resistance, postprandial hyperlipidemia and cardiovascular risk in HIV-infected patients. Strategies to reduce cardiovascular risk are also discussed.