Host factors may be more important than choice of antiretrovirals in the development of lipoatrophy

Peripheral fat loss, or lipoatrophy, has been reported as an emerging complication of long-term antiretroviral regimens, mainly when nucleoside analogues are included. However, lipoatrophy does not develop in the majority of nucleoside inhibitor-treated patients, leading to the investigation of factors other than drug effects alone as potential contributors to this complication. We conducted a retrospective cohort study study and analysis of repository plasma samples taken from HIV-infected patients being treated with their initial antiretroviral regimen. CD4 cell count and plasma tumor necrosis factor (TNF), soluble TNF receptors, and leptin levels were assessed and correlated with the development of lipoatrophy. The most significant treatment-related factor in this study of patients on their first drug regimen was duration of antiretroviral therapy, rather than type of nucleoside inhibitor treatment. No association was found between lipoatrophy and specific nucleoside inhibitors, including zidovudine and stavudine. A significant association between lipoatrophy was found for 2 nondrug risk factors: older age and lower pretherapy body mass index. Our results emphasize the need for keeping in mind the role of host factors in the generation of lipoatrophy.

Lipodystrophy in human immunodeficiency virus patients impairs insulin action and induces defects in beta-cell function

The pathophysiology of insulin resistance in human immunodeficiency virus (HIV)-associated lipodystrophy syndrome (HALS) is not fully clarified. We investigated 18 men with HALS and 18 HIV-positive males without lipodystrophy (control subjects). Duration and modality of antiretroviral therapy were similar between study groups. A hyperinsulinemic euglycemic clamp showed an impaired glucose disposal rate (GDR) in HALS patients (5.6 v 8.3 mg glucose/min. kg(FFM), P =.0006). As demonstrated by indirect calorimetry, HALS patients showed an impaired nonoxidative glucose metabolism (NOGM, 2.2 v 4.2, P =.006), whereas levels of basal and insulin-stimulated oxidative glucose metabolism (OGM) (2.4 v 2.3, P =.55, and 3.3 v 4.0, P =.064, respectively) were not significantly different between groups. Despite comparable total fat masses, dual energy x-ray absorptiometry (DEXA) scans showed that the percentage of limb fat (ie, peripheral-fat-mass/[peripheral-fat-mass + trunk-fat-mass]. 100%) was reduced in HALS patients (36% v 46%, P =.0002). Multiple linear regression analysis indicated that percentage of limb fat explained 53% of the variability of GDR and 45% of the variability of NOGM in HALS patients. In HALS patients, leg fat mass correlated positively with NOGM (r =.51, P <.05), whereas abdominal fat mass and NOGM did not correlate (P =.91). Analyzing the relationship between first phase insulin secretion and insulin sensitivity, 6 HALS patients compared with none of the control subjects exhibited impaired insulin secretion (P <.05). Our data suggest that fat redistribution independently of antiretroviral therapy is highly related to insulin resistance in HALS patients. Furthermore, in HALS patients, impaired glucose metabolism most likely relates to decreased NOGM and to defects in beta-cell function.

Practical applications of the HIV lipodystrophy case definition

Diagnosis of HIV-associated lipodystrophy (LD) has been limited by the absence of a validated case definition and the frequent lack of objective body composition measures. An international, objective, case-control study recruited HIV-infected, adult outpatients free of active AIDS, and a case definition model for LD was developed. The relative merits and limitations of this definition as a practical tool for the long-term monitoring of a patient's LD status over the duration of clinical treatment are discussed.

HIV lipodystrophy case definition using artificial neural network modelling

OBJECTIVE

A case definition of HIV lipodystrophy has recently been developed from a combination of clinical, metabolic and imaging/body composition variables using logistic regression methods. We aimed to evaluate whether artificial neural networks could improve the diagnostic accuracy.

METHODS

The database of the case-control Lipodystrophy Case Definition Study was split into 504 subjects (265 with and 239 without lipodystrophy) used for training and 284 independent subjects (152 with and 132 without lipodystrophy) used for validation. Back-propagation neural networks with one or two middle layers were trained and validated. Results were compared against logistic regression models using the same information.

RESULTS

Neural networks using clinical variables only (41 items) achieved consistently superior performance than logistic regression in terms of specificity, overall accuracy and area under the ROC curve. Their average sensitivity and specificity were 72.4 and 71.2%, as compared with 73.0 and 62.9% for logistic regression, respectively (area under the ROC curve, 0.784 vs 0.748). The discriminating performance of the neural networks was largely unaffected when built excluding 13 parameters that patients may not have readily available. The average sensitivity and specificity of the neural networks remained the same when metabolic variables were also considered (total 60 items) without a clear advantage against logistic regression (overall accuracy 71.8%). The performance of networks considering also body composition variables was similar to that of logistic regression (overall accuracy 78.5% for both).

CONCLUSIONS

Neural networks may offer a means to improve the discriminating performance for HIV lipodystrophy, when only clinical data are available and a rapid approximate diagnostic decision is needed. In this context, information on metabolic parameters is apparently not helpful in improving the diagnosis of HIV lipodystrophy, unless imaging and body composition studies are also obtained.

Studies of adipose tissue metabolism in human immunodeficiency virus-associated lipodystrophy

We studied aspects of metabolism in subcutaneous adipose tissue (SAT) in 40 human immunodeficiency virus (HIV)-infected subjects with and without lipodystrophy and in healthy control subjects. HIV-infected subjects without lipodystrophy had less SAT and visceral adipose tissue (VAT). Glycerol release was higher in both HIV-infected groups, especially those without fat redistribution. Tumor necrosis factor (TNF) release from SAT and serum soluble TNF receptor 2 concentrations were significantly higher in HIV-infected individuals with lipodystrophy. The absolute production of acylation-stimulating protein (ASP) and the percentage conversion of the complement protein to ASP were significantly lower in HIV-infected subjects with lipodystrophy. Further studies are needed to dissect the factors that mediate lipoatrophy in HIV infection.

Turnover of adipose components and mitochondrial DNA in humans: kinetic biomarkers for human immunodeficiency virus-associated lipodystrophy and mitochondrial toxicity?

Lipoatrophy (LA)/lipodystrophy and nucleoside reverse-transcriptase inhibitor (NRTI)-associated syndrome are of central importance in human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) care. Neither of these conditions has had a clear pathogenesis or biomarker defined for early detection, prevention research, or patient management. I describe the recent development of kinetic biomarkers for LA and mitochondrial toxicity that involve the measurement of biosynthetic fluxes rather than static concentrations of molecules. The turnover of adipose-tissue components (lipids and cells) and tissue mitochondrial DNA is measured by the incorporation of deuterium from heavy water, using mass spectrometry. Preliminary results in animal models and humans, including the effects of NRTIs on mitochondrial DNA synthesis in rats and adipose-tissue lipid kinetics in HIV-associated LA, are reviewed. The results suggest that the kinetics of adipose-tissue components and mitochondrial DNA are measurable in vivo and that these measurements may prove useful as clinical biomarkers in patients with HIV/AIDS.

Alterations in lipid kinetics in men with HIV-dyslipidemia

Hypertriglyceridemia is common in individuals with human immunodeficiency (HIV) infection, but the mechanisms responsible for increased plasma triglyceride (TG) concentrations are not clear. We evaluated fatty acid and VLDL-TG kinetics during basal conditions and during a glucose infusion that resulted in typical postprandial plasma glucose and insulin concentrations in six men with HIV-dyslipidemia [body mass index (BMI): 28 +/- 2 kg/m2] and six healthy men (BMI: 26 +/- 2 kg/m2). VLDL-TG secretion and palmitate rate of appearance (Ra) in plasma were measured by using stable-isotope-labeled tracer techniques. Basal palmitate Ra and VLDL-TG secretion rates were greater (P < 0.01 for both) in men with HIV-dyslipidemia (1.04 +/- 0.07 micromol palmitate x kg-1 x min-1 and 5.7 +/- 0.6 micromol VLDL-TG x l plasma-1 x min-1) than in healthy men (0.67 +/- 0.08 micromol palmitate. kg-1 x min-1 and 3.0 +/- 0.5 micromol VLDL-TG x l plasma-1 x min-1). Basal VLDL-TG plasma clearance was lower in men with HIV-dyslipidemia (13 +/- 1 ml/min) than in healthy men (19 +/- 2 ml/min; P < 0.05). Glucose infusion decreased palmitate Ra (by approximately 50%) and the VLDL-TG secretion rate (by approximately 30%) in both groups, but the VLDL-TG secretion rate remained higher (P < 0.05) in subjects with HIV-dyslipidemia. These findings demonstrate that increased secretion of VLDL-TG and decreased plasma VLDL-TG clearance, during both fasting and fed conditions, contribute to hypertriglyceridemia in men with HIV-dyslipidemia. Although it is likely that increased free fatty acid release from adipose tissue contributes to the increase in basal VLDL-TG concentration, other factors must be involved, because insulin-induced suppression of lipolysis and systemic fatty acid availability did not normalize the VLDL-TG secretion rate.

Effect of antioxidants on glucose metabolism and plasma lipids in HIV-infected subjects with lipoatrophy

Ten HIV-infected nucleoside reverse transcriptase inhibitor-treated subjects with lipoatrophy or sustained hyperlactatemia were given antioxidants: vitamins C, E, and N-acetyl cysteine. After 24 weeks, anthropometrics did not change significantly, except for a modest decrease in the waist-to-hip ratio. Fasting low-density lipoprotein cholesterol trended toward lower values. Fasting glucose significantly increased along with a significant increase in homeostatic model assessment values, reflecting an increase in insulin resistance. Controlled trials are required to evaluate directly the effects of these agents on lipid and glucose metabolism.

Peroxisome proliferator-activated receptors in cutaneous biology

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that regulate the expression of target genes involved in many cellular functions including cell proliferation, differentiation and immune/inflammation response. The PPAR subfamily consists of three isotypes: PPAR alpha, PPAR beta/delta and PPAR gamma, which have all been identified in keratinocytes. PPAR beta/delta is the predominant subtype in human keratinocytes, whereas PPAR alpha and PPAR gamma are expressed at much lower levels and increase significantly upon keratinocyte differentiation. PPAR beta/delta is not linked to differentiation, but is significantly upregulated upon various conditions that result in keratinocyte proliferation, and during skin wound healing. In vitro and in vivo evidence suggests that PPARs appear to play an important role in skin barrier permeability, inhibiting epidermal cell growth, promoting epidermal terminal differentiation and regulating skin inflammatory response by diverse mechanisms. These proprieties are pointing in the direction of PPARs being key regulators of skin conditions characterized by hyperproliferation, inflammatory infiltrates and aberrant differentiation such as psoriasis, but may also have clinical implications in inflammatory skin disease (e.g. atopic dermatitis), proliferative skin disease, wound healing, acne and protease inhibitor associated lipodystrophia.

HIV infection--a risk factor for osteoporosis

Osteopenia and osteoporosis have recently been described as complications of antiretroviral therapy in HIV-infected patients. The advent of highly active antiretroviral therapy in conjunction with improved standard antiviral and antibiotic regimens has dramatically changed the clinical course of HIV infection, resulting in prolonged survival. The pathogenesis and role of each individual medication are poorly understood. Avascular necrosis has also been described in AIDS patients receiving or not receiving antiretroviral therapy. This article is a clinically focused review of the literature on osteopenia, osteoporosis, and mineral metabolism related to HIV infection. In patients with HIV infection, the risks of osteopenia and osteoporosis are not very clear. The suggested risk factors for the development of osteopenia are use of protease inhibitors, longer duration of HIV infection, high viral load, high lactate levels, low bicarbonate levels, raised alkaline phosphatase level, and lower body weight before antiretroviral therapy. There have also been a few case reports of pathologic fractures in AIDS patients with antiretroviral therapy-induced osteopenia and osteoporosis. The underlying mechanism triggering bone loss in HIV-infected patients is unknown. The proinflammatory cytokines tumor necrosis factor and interleukin-6 have been found to be constitutionally produced in increased amounts in HIV-positive individuals, and they may have a role in osteoclast activation and resorption. Serum markers of bone formation are decreased and resorption is increased in patients with advanced clinical disease. Hypocalcemia, hypercalcemia, and abnormalities of the parathyroid hormone axis have been described in HIV infection. Histomorphometric analyses have shown altered bone remodeling in HIV-infected patients when compared with controls. Patients with known risk factors for osteoporosis-advancing age, low body weight, and prolonged duration of HIV infection-and those receiving protease inhibitor treatment should be considered for dual x-ray absorptiometry imaging. If bone mineral density is osteopenic or osteoporotic, then the patient should also be screened for other known medical causes of osteoporosis and consider treatment with a bisphosphonate or, if hypogonadal, testosterone replacement under close monitoring.

Exercise and vitamin E intake are independently associated with metabolic abnormalities in human immunodeficiency virus-positive subjects: a cross-sectional study

We investigated the relationship among habitual exercise, diet, and the presence of metabolic abnormalities (body fat redistribution, dyslipidemia, and insulin resistance) in a cross-sectional study of 120 human immunodeficiency virus (HIV)-infected subjects with use of bivariate and multivariate regression-analysis models. Total and aerobic exercise were significantly and negatively associated with fasting plasma triglyceride levels in the entire sample and in the fat redistribution group. Inverse associations between total or aerobic exercise and insulin resistance were suggestive but did not achieve statistical significance. Diastolic blood pressure was significantly and inversely associated with supplemental or total but not habitual dietary intake of vitamin E. In conclusion, exercise and vitamin E intake were independently and negatively associated with several phenotypic manifestations of HIV-associated metabolic syndrome, whereas other macro- or micronutrients did not have comparable significance.

AIDS-related insulin resistance and lipodystrophy syndrome

The recent development of highly active antiretroviral therapy (HAART) has drastically improved the life expectancy of AIDS patients, by reducing infection-related mortality. However, the prolongation of the lives of HIV-1-infected patients and/or the long-term use of novel, potent antiviral agents have generated a score of new problems and complications. Among them is the AIDS-related insulin resistance and lipodystrophy syndrome, which is observed in 30-80% of AIDS patients who are well controlled by HAART. This syndrome is associated with severe metabolic disturbances, such as carbohydrate intolerance/diabetes mellitus and dyslipidemia, which cause atherosclerotic cardiovascular disease. The etiology of this syndrome appears to be multi-factorial; other than the anti-viral drugs, hypercytokinemia and the HIV-1 infection itself, including the virally encoded molecules Vpr and Tat, could contribute to the development of these pathologic changes or increase the vulnerability of patients to the adverse effect of the therapeutic compounds. In this article, we review our current understanding of the pathogenesis and therapeutic approach of this newly emerging AIDS-associated metabolic syndrome.

Prospective evaluation of the effects of antiretroviral therapy on body composition in HIV-1-infected men starting therapy

OBJECTIVE

Little prospective data are published on the natural history of HIV-associated lipodystrophy (HIVLD) in individuals beginning their first antiretroviral regimen. To investigate this a study was designed to explore changes in body composition occurring with antiretroviral therapy.

STUDY DESIGN

A non-randomized, prospective, exploratory study of 40, HIV-infected men, naive to treatment, beginning antiretroviral therapy. Regular assessments of body composition, and metabolic and immunological parameters were performed.

RESULTS

Mean follow-up was 96 (SD 45) weeks of therapy. There were increases in limb fat, central abdominal fat and lean mass over the initial 24 weeks of therapy followed by a selective, progressive loss of limb fat from week 24. There was a median 13.6% [interquartile range (IQR), 0.9-26.3] loss of limb fat per year from week 24 onwards. Treatment with stavudine, higher baseline HIV RNA, higher baseline 'T' score and lower week 24 lean mass were associated with higher rate of limb fat loss from week 24. In multivariate analysis, treatment with stavudine was the strongest independent factor associated with rate of limb fat loss (P = 0.05). Hypercholesterolaemia developed early in treatment, whereas hypertriglyceridaemia, hyperinsulinaemia and decreased bone mineral density developed later. The largest changes in CD4 cell counts and HIV viral load, seen early into treatment, were associated with gain rather than loss of fat.

CONCLUSIONS

This is the first prospective study demonstrating that treatment with antiretrovirals results in progressive, selective loss of limb fat. Loss of limb fat occurred after the period of most intense immune restoration, making an immune aetiology unlikely.

Endothelial markers and HIV infection in the era of highly active antiretroviral treatment

Many circumstances can induce activation and/or injury of the endothelium that plays a role in the development of vascular complications. Raised plasma levels of endothelial markers such as von Willebrand factor (vWF), soluble thrombomodulin (sTM) and soluble vascular cell adhesion molecule-1 (sVCAM-1) have a prognostic and/or diagnostic value. Human immunodeficiency virus-infected patients (HIV+) have a clustering of conditions that activate or injure the endothelium. Highly active antiretroviral treatment produces adverse effects such as dyslipemia, insulin resistance (IR) and body fat changes (named lipodystrophy syndrome) which may contribute to aggravate their endothelial perturbation. The aim of this study was to measure lipid profile, insulin resistance status, and endothelial markers in 38 HIV+ naive of antiretroviral treatment and 63 HIV+ under highly active antiretroviral treatment (33 with lipodystrophy syndrome and 30 without it). Body fat distribution was also evaluated by dual-energy X-ray absorptiometry (DEXA) analysis. Thirty-one HIV negative subjects were used as controls. We looked for association between variables. Insulin resistance status was a common finding in the four groups. Lipodystrophic patients presented an atherothrombotic lipid profile [elevated levels of triglycerides (TG), low-density lipoprotein cholesterol (LDL-chol) and apolipoprotein-B (APO-B)] and a strong loss of fat in legs and arms (lipoatrophy). All endothelial markers evaluated in our naive patients were higher as compared to control group. sVCAM-1 in HIV+ under therapy without lipodystrophy syndrome showed significantly decreased levels as compared to naive group (487 vs. 666 ng/ml) and vWF and sTM tended to diminish although they did not show a significant difference (130% vs. 170%, 41 vs. 45 ng/ml, respectively). Lipodystrophic patients showed a tendency to increased levels of endothelial activation markers (sVCAM-1: 500 ng/ml and vWF: 154%) together with significantly increased levels of an endothelial injury marker (sTM: 50 ng/ml) with respect to HIV+ under therapy without lipodystrophy syndrome. Plasma levels of sTM, as an endothelial injury marker, correlated with peripheral lipoatrophy (rho = -0.357) in lipodystrophic patients. In conclusion, despite the beneficial immunology effect of highly active antiretroviral treatment and the apparent decrease in the endothelial perturbation, the patients who develop lipodystrophy present altered endothelial markers and other risk factors, such as IR and dyslipemia, which turn them into a high atherothrombotic risk group.

Total energy expenditure and carbohydrate oxidation are increased in the human immunodeficiency virus lipodystrophy syndrome

To determine whether total energy expenditure (TEE) is increased in the human immunodeficiency virus (HIV) lipodystrophy syndrome, we compared energy expenditure (EE) and substrate oxidation rates in 12 HIV-infected men with lipodystrophy, 7 HIV-infected men without lipodystrophy, and 14 healthy controls. TEE and nutrient oxidation rates were assessed by whole-room indirect calorimetry. Resting energy expenditure (REE) was measured by indirect calorimetry using the open-circuit technique. Body composition was assessed by dual-energy x-ray absorptiometry (DEXA). Insulin sensitivity was measured using the insulin-modified frequently sampled intravenous glucose tolerance test. TEE adjusted for lean body mass (LBM) was significantly higher in the HIV-infected group with lipodystrophy compared to HIV-infected patients without lipodystrophy (2,873.3 +/- 69 v 2,573.9 +/- 92 kcal/d, P =.02) and compared to healthy controls (2,873.3 +/- 69 v 2,404.0 +/- 64 kcal/d, P <.001). REE and sleeping metabolic rate (SMR) adjusted for LBM were also significantly higher in the HIV-infected group with lipodystrophy compared to both HIV-infected and healthy controls. Carbohydrate oxidation rates adjusted for LBM were higher in men with HIV lipodystrophy as compared to healthy controls (362.5 +/- 23 v 250.0 +/- 22 g/d, P = <.01) and tended to be higher as compared to HIV-infected controls (362.5 +/- 23.6 v 297.3 +/- 31 g/d, P =.1). In conclusion, TEE and carbohydrate oxidation are increased in the HIV lipodystrophy syndrome. The increase in TEE appears to be due to increases in REE. The pathogenesis of elevated EE in HIV lipodystrophy and other forms of lipodystrophy remains to be determined.

HIV lipodystrophy diagnosis and management. Body composition and metabolic alterations: diagnosis and management

Body composition alterations are common in HIV infection and include AIDS wasting and lipodystrophy. Both are associated with metabolic alterations, including hypertriglyceridemia and reduced high-density lipoprotein cholesterol levels; insulin resistance and elevated low-density lipoprotein cholesterol levels are also associated with lipodystrophy. However, there is no accepted case definition for HIV-associated lipodystrophy, and patients may have one or all aspects at any given time. The inability of cross-sectional studies to capture the dynamic process of these alterations has hindered the search for a case definition. In the meantime, there are several approaches to treatment of the resulting abnormalities. Switching antiretrovirals has been most successful for improving metabolism, with little or not effect on fat distribution. Growth hormone treatment has successfully reduced visceral fat and buffalo humps but is not FDA-approved for this indication. Metformin and rosiglitazone have produced some improvement in fat distribution as well as glucose metabolism. Other methods that have been tried with varying degrees of success (and little published data) include treatment with testosterone and its derivatives, weight reduction through diet and exercise, and plastic surgery.

Insulin resistance in HIV-related lipodystrophy

Lipodystrophy (LD) associated with HIV infection is a syndrome of abnormal fat distribution observed in HIV-infected patients treated with various antiretroviral agents. In addition, insulin resistance and dyslipidemia can occur in HIV-infected patients with or without LD. The demonstration of the latter metabolic disorders in normal subjects using protease inhibitors suggests that these agents could play a causative role in their development independently of HIV status. Possible mechanisms whereby protease inhibitors can hinder insulin actions include inhibition of glucose transporter isoform Glut 4, and altered expression of leptin and tumor necrosis factor-a in adipose tissue. The presence of insulin resistance and dyslipidemia can potentially increase the risk of diabetes, cardiovascular disease, and death. However, short-term data in this regard are inconsistent. Treatment of HIV-related LD with metformin may ameliorate insulin resistance, but its impact on fat redistribution requires additional studies. Temporary cessation of antiretroviral therapy does not appear to reverse body fat changes or insulin resistance, but may partially improve the lipid profile. Further investigations are urgently needed to define the mechanisms and cardiovascular consequences of insulin resistance in HIV-related LD, and to find an effective treatment for this complex syndrome.

HIV lipodystrophy etiology and pathogenesis. Body composition and metabolic alterations: etiology and pathogenesis

The results of epidemiologic investigations have clearly indicated that the development of lipodystrophy is multifactorial. Factors related to HIV infection, hormonal influences, mitochondrial dysfunction, cytokine activation related to immune reconstitution, and individual genetic predisposition all have been hypothesized as etiologic. Recent studies suggest that immune dysregulation rather than HIV infection per se may be the predominant factor in the development of lipodystrophy.

Clinical impact of HIV-related lipodystrophy and metabolic abnormalities on cardiovascular disease

Metabolic complications and altered fat distribution associated with HIV infection and antiretroviral therapy may lead to accelerated coronary artery disease (CAD). The high prevalence of multiple cardiovascular risk factors in a significant number of HIV patients is a cause for concern in both patients and physicians. Non-invasive strategies to measure subclinical CAD have been inconclusive. Long-term studies are underway to determine cardiac event rates, intervention strategies and consequences for the clinical management of HIV disease. In the present paper, we summarize the most prevalent risk factors in individuals with HIV infection receiving highly active antiretroviral therapy by focusing on the clinical implications of metabolic abnormalities and HIV-related lipodystrophy on CAD.

Fat Distribution and Metabolic Abnormalities in HIV-Infected Patients on First Combination Antiretroviral Therapy Including Stavudine or Zidovudine: Role of Physical Activity as a Protective Factor

Objective

To compare body composition, serum lipid profile, parameters of insulin secretion and endocrine measurements in HIV-1-infected patients whose first combination antiretroviral regimen differed only in a nucleoside reverse transcriptase inhibitor (NRTI).

Design and setting

Cross-sectional study in an AIDS clinic of a university hospital.

Patients

One-hundred-and-fifty HIV-infected patients on long-term first highly active antiretroviral therapy including stavudine (n=75) or zidovudine (n=75).

Main outcome measure

Fat wasting was assessed by physical examination. Regional fat distribution was estimated using calliper measurements of skinfold thickness at four sites. Central adiposity was assessed by measurement of waist–hip ratio. Fasting glucose, insulin, triglyceride, cholesterol and its fractions, testosterone, follicle stimulating hormone, luteinizing hormone levels, CD4 cell count and HIV viral load were determined. Daily caloric intake and physical activity level were also calculated.

Results

Total body fat was significantly lower in patients taking stavudine, whereas the lean body mass was not statistically different amongst both groups. Ninety-four patients (62.7%; 95% CI: 54.9–70.4%) had fat redistribution, being isolated lipoatrophy in 20 (13.3%; 95% CI: 7.9–18.8%), isolated lipohypertrophy in 33 (22.0%; 95% CI: 15.4–28.6%) and mixed syndrome in 41 (27.3%; 95% CI: 20.2–34.5%). There were not statistically significant differences between stavudine- and zidovudine-treated patients with respect to the overall prevalence of fat redistribution syndromes (P=0.34). The prevalence of lipoatrophy (OR=1.86; 95% CI: 0.58–6.33, P=0.37), lipohypertrophy (OR=0.65; 95% CI: 0.25–1.69, P=0.45) and mixed syndromes (OR=1.05; 95% CI: 0.43–2.54, P=0.93) was not statistically different in both groups of patients. The only independent predictor for the appearance of mixed syndrome and lipoatrophy was sedentarism (OR=4.418; 95% CI: 1.565–12.472, P=0.005) and (OR=4.515; 95% CI: 1.148–17.761, P=0.03), respectively. Independent predictors of lipohypertrophy were age (OR=1.138; 95% CI: 1.061–1.220, P<0.0001) and prior AIDS (OR=0.305; 95% CI: 0.100–0.931, P=0.04). There were no statistically significant differences between stavudine and zidovudine-based groups with respect to metabolic and hormonal parameters.

Conclusion

The use of stavudine or zidovudine in the context of the first combination antiretroviral therapy is not associated either with an increased likelihood of lipid or gonadal hormones abnormalities, and although there was a trend to a lesser body fat content in the stavudine group, there was no increase in the overall likelihood of fat redistribution syndromes with respect to zidovudine group. Physical activity is a protective factor for the development of fat redistribution syndromes.

Adipocyte-derived hormone levels in HIV lipodystrophy

OBJECTIVE

Despite evidence for the role of adipocyte-derived hormones in insulin resistance, little is known about their levels in human lipodystrophic states. We examined the relationships of plasma leptin and adiponectin levels to fat distribution and insulin sensitivity in the HIV lipodystrophy syndrome.

DESIGN

Cross-sectional study

SETTING

HIV primary care practices

PATIENTS

HIV-infected men with (n=13) and without (12) lipodystrophy and healthy uninfected controls (12).

MAIN OUTCOME MEASURES

Plasma adiponectin and leptin levels were measured in the fasting state. Body composition was assessed by physical examination, dual-energy x-ray absorptiometry and computed tomography. Insulin sensitivity (S(I)) was measured using the insulin-modified frequently sampled intravenous glucose tolerance test.

RESULTS

Leptin levels were significantly higher in HIV-infected men with lipodystrophy as compared to HIV-infected controls (5.2 vs 3.0 ng/ml, P=0.01). Across the entire study population, leptin levels were positively correlated with measures of general adiposity. In the HIV-infected patients, leptin levels were negatively correlated with S(I) after adjustment for fat mass (r=-0.38, P=0.07). Adiponectin levels were significantly lower in HIV-infected men with lipodystrophy as compared to both HIV-infected and healthy controls (1.6 vs 3.4 microg/ml, P<0.05 and 1.6 vs 6.7 microg/ml, P<0.001, respectively). Adiponectin levels, after adjustment for fat mass, were correlated with measures of fat distribution. Finally, in the HIV-infected patients, adiponectin levels were significantly and positively correlated with S(I) after adjustment for fat mass (r=0.75, P < or = 0.001), and adiponectin level was also an independent determinant of S(I).

CONCLUSIONS

Plasma leptin and adiponectin levels are altered in the HIV lipodystrophy syndrome. Adiponectin deficiency may play a role in the insulin resistance associated with HIV lipodystrophy.

Tests for mitochondrial function and DNA: potentials and pitfalls

PURPOSE OF REVIEW

In the past few years, mitochondria have been carefully studied to ascertain whether and how in patients affected by HIV antiretroviral therapy is able to alter their functionality and exert a toxic effect on immune cells, as well as on cells present in other districts.

RECENT FINDINGS

A variety of in-vivo and ex-vivo models have been developed to investigate the functionality of mitochondria and DNA during a variety of physiopathological situations, including HIV infection and its treatment. Numerous technologies are available to study at the single-cell or at the single-organelle level a variety of parameters, such as membrane potential, the activity of respiratory chain enzymes, and DNA content or its sequence. As far as in-vitro studies are concerned, a substantial homogeneity of data exists, and several changes in different mitochondrial parameters have been described that depend upon the drug used, the cell model and the parameter investigated. On the other hand, different results have been reported on biological material collected from HIV-positive patients and immediately analysed. Ex-vivo studies showed that changes in mitochondrial DNA content or in the functionality of the organelle exist in some tissues or cells, but not in others.

SUMMARY

One of the possible causes of the discrepancies is the technologies used to investigate mitochondria, and this paper summarizes some of the pros and cons of the main methods used to study mitochondrial function or DNA.

Intramyocellular lipid accumulation and reduced whole body lipid oxidation in HIV lipodystrophy

Antiretroviral therapy in human immunodeficiency virus (HIV)-positive patients can induce a lipodystrophy syndrome of peripheral fat wasting and central adiposity, dyslipidemia, and insulin resistance. To test whether in this syndrome insulin resistance is associated with abnormal muscle handling of fatty acids, 12 HIV-1 patients (8 females/4 males, age = 26 +/- 2 yr, HIV duration = 8 +/- 1 yr, body mass index = 22.0 +/- 1.0 kg/m(2), on protease inhibitors and nucleoside analog RT inhibitors) and 12 healthy subjects were studied. HIV-1 patients had a total body fat content (assessed by dual-energy X-ray absorptiometry) similar to that of controls (22 +/- 1 vs. 23 +/- 2%; P = 0.56), with a topographic fat redistribution characterized by reduced fat content in the legs (18 +/- 2 vs. 32 +/- 3%; P < 0.01) and increased fat content in the trunk (25 +/- 2 vs. 19 +/- 2%; P = 0.03). In HIV-positive patients, insulin sensitivity (assessed by QUICKI) was markedly impaired (0.341 +/- 0.011 vs. 0.376 +/- 0.007; P = 0.012). HIV-positive patients also had increased total plasma cholesterol (216 +/- 20 vs. 174 +/- 9 mg/dl; P = 0.05) and triglyceride (298 +/- 96 vs. 87 +/- 11 mg/dl; P = 0.03) concentrations. Muscular triglyceride content assessed by means of (1)H NMR spectroscopy was higher in HIV patients in soleus [92 +/- 12 vs. 42 +/- 5 arbitrary units (AU); P < 0.01] and tibialis anterior (26 +/- 6 vs. 11 +/- 3 AU; P = 0.04) muscles; in a stepwise regression analysis, it was strongly associated with QUICKI (R(2) = 0.27; P < 0.0093). Even if the basal metabolic rate (assessed by indirect calorimetry) was comparable to that of normal subjects, postabsorptive lipid oxidation was significantly impaired (0.30 +/- 0.07 vs. 0.88 +/- 0.09 mg x kg(-1) x min(-1); P < 0.01). In conclusion, lipodystrophy in HIV-1 patients in antiretroviral treatment is associated with intramuscular fat accumulation, which may mediate the development of the insulin resistance syndrome.

Severe insulin resistance contrasting with mild anthropometric changes in the adipose tissue of HIV-infected children with lipohypertrophy

BACKGROUND

The HIV-associated lipodystrophic syndrome (HIV-LDS) combines redistribution of fat mass with insulin resistance and hyperlipidemia. We have previously reported that HIV-LDS prevails in children in a comparable pattern as in adults. The metabolic activity itself of the lipodystrophic adipose tissue in HIV infection has been poorly studied.

AIM AND METHODS

To assess in situ the insulin sensitivity of the lipohypertrophic subcutaneous abdominal adipose tissue using the microdialysis technique in HIV-infected children. Insulin sensitivity, assessed by the inhibition of glycerol release, was measured in the abdominal subcutaneous adipose tissue during a standard oral glucose tolerance test (OGTT) in six HIV-infected children under multi-therapy with abdominal lipohypertrophy (supra-iliac skinfold thickness >97th percentile) (HIV/LH+), in six obese children (obese group) and in eight HIV-infected children without lipodystrophy (HIV/LH-).

RESULTS

Glucose tolerance was normal in all subjects. Mean insulin areas under the curve (IAUC) were significantly higher in the obese and HIV/LH+ groups than in HIV/LH- (8769+/-5429, 8161+/-4552 and 3618+/-2222 mU min l(-1), respectively; P=0.04 for the three groups comparison by the Kruskal-Wallis test), reflecting insulin resistance in the two former groups independent of a significant difference in percentage fat mass (37.2+/-4.7, 22.8+/-10.9 and 20.7+/-7.1%, respectively; P= 0.006). The crude inhibition of glycerol release, expressed as the relative change in dialysate glycerol concentration between baseline and 120 min, was not statistically different between the three groups (14% in obese, -38+/-14% in HIV/LH+ and -51+/-17% in HIV/LH- groups; P=0.3). The inhibition of glycerol release with respect to the circulating insulin level (expressed by IAUC) was similar in HIV/LH+ and obese groups (-6+/-5 x 10(-3) and -7+/-5 x 10(-3) l mU(-1) min(-1), respectively, P=0.4 for two-groups comparison by the U-Mann-Whitney test) and four-fold less than in the HIV/LH- group (-24+/-25 x 10(-3) l mU(-1) min(-1); P=0.02).

CONCLUSION

These data argue in favor of insulin resistance in the adipose tissue of lipohypertrophies associated with HIV infection.

Paracrine relationships between adipose and lymphoid tissues: implications for the mechanism of HIV-associated adipose redistribution syndrome

The adipocytes anatomically associated with lymph nodes and omental milky spots have site-specific properties that equip them to interact locally with lymphoid cells. Paracine provisioning of peripheral immune responses improves their efficiency and emancipates activated lymphocytes from competition with other tissues for blood-borne nutrients. Prolonged disruption to such paracine interactions might contribute to the HIV-associated adipose redistribution syndrome, causing selective hypertrophy of the mesentery, omentum and other lymphoid tissue-containing adipose depots, while nodeless depots atrophy.

Bezafibrate-induced improvement in glucose uptake and endothelial function in protease inhibitor-associated insulin resistance

Protease inhibitors used as therapy for HIV-1 infection have been associated with metabolic side-effects such as peripheral fat wasting, central adiposity, hyperlipidaemia and insulin resistance. This metabolic disorder is known as the lipodystrophy syndrome. This syndrome can be recognized by the early appearance of an increase in serum triglyceride, cholesterol and plasma-free fatty acid levels. Here, we describe an HIV-1 positive patient with the lipodystrophy syndrome in whom a decline in serum triglycerides was seen along with a significant improvement in glucose uptake following treatment with bezafibrate for 3 months. This improvement may be a consequence of the Randle effect, i.e. increased availability of plasma-free fatty acids is negatively correlated to glucose uptake. We also noted a significant improvement in endothelial-dependent flow-mediated dilatation after treatment with bezafibrate. This effect could result from the increased glucose uptake observed and a decrease in insulin resistance secondary to the lowered triglyceride levels by bezafibrate. We conclude that bezafibrate may be of clinical utility in the lipodystrophy syndrome, through its beneficial effects on insulin resistance, glucose uptake and endothelial dysfunction.

Increased fat accumulation in the liver in HIV-infected patients with antiretroviral therapy-associated lipodystrophy

OBJECTIVE

To determine liver fat content in patients with highly active antiretroviral therapy (HAART)-associated lipodystrophy.

BACKGROUND

Lipodystrophy in several animal models is associated with fat accumulation in insulin-sensitive tissues, such as the liver. This causes hyperinsulinaemia, dyslipidaemia and other features of insulin resistance.

DESIGN

A cross-sectional study.

SUBJECTS AND METHODS

Three age- and weight-matched groups were compared: 25 HIV-positive men with HAART-associated lipodystrophy (HAART+LD+), nine HIV-positive men receiving HAART, but without lipodystrophy (HAART+LD-), and 35 HIV-negative healthy men (HIV-). Liver fat content was measured using proton spectroscopy. Intra-abdominal and subcutaneous fat were determined using magnetic resonance imaging.

RESULTS

Liver fat content was significantly higher in the HAART+LD+ (8 +/- 10%) than the HIV- (5 +/- 7%; P < 0.05) or the HAART+LD- (3 +/- 5%; P < 0.01) group. Liver fat content correlated with serum fasting insulin in the HAART+LD+ (r = 0.47; P < 0.05) and HIV- groups (r = 0.65; < 0.001), but not with the amount of intra-abdominal fat. Within the HAART+LD+ group, serum insulin did not correlate with the amount of intra-abdominal fat. The HAART+LD+ group had a lower serum leptin concentration when compared to the two other groups. Features of insulin resistance, including hepatic fat accumulation, were not found in HAART+LD-group.

CONCLUSIONS

The severity of the insulin resistance syndrome in patients with HAART-associated lipodystrophy is related to the extent of fat accumulation in the liver rather than in the intra-abdominal region. Fat accumulation in the liver may therefore play a causative role in the development of insulin resistance in these patients.

HIV-associated lipodystrophy: description, pathogenesis, and molecular pathways

HIV-infected individuals taking antiretroviral medications may experience changes in body shape and metabolism, commonly known as HIV-associated lipodystrophy (HIVLD). In vitro and in vivo research have revealed numerous effects of both protease inhibitors and nucleoside reverse transcriptase inhibitors on the function of various organs--most importantly adipose tissue, liver, and muscle. The metabolic abnormalities could result in an increased risk of cardiovascular disease in this vulnerable and relatively young population. Treatment strategies, normally successful in the general population, have generally been less effective in this group of people, in which the detrimental effects of the antiretroviral medications are ongoing.