Lipoatrophy, fat accumulation, and mixed syndrome in protease inhibitor-naive HIV-infected patients

Prevalence of and Risk Factors for Pubic Lipoma Development in HIV-Infected Persons

BACKGROUND

The natural history of HIV-associated body habitus changes is unclear. In this report, we describe a novel manifestation of HIV-associated lipoaccumulation.

METHODS

We noted the presence of suprapubic fat pads (pubic lipomas [PLs]) in several patients with preexisting HIV-associated body habitus abnormalities. Subsequently, we evaluated the prevalence of and associated risk factors for development of PLs by undertaking an observational cross-sectional study among patients with known lipodystrophy who attended a metabolic clinic in northern Italy. Inclusion criteria were a physician-confirmed diagnosis of lipodystrophy according to the Multicenter AIDS Cohort Study definition and, for those affected with PL, a readily noticeable PL on physical examination.

RESULTS

We evaluated 582 patients with lipodystrophy: 214 female (36.7%) and 368 male (63.3%). The overall PL prevalence was 9.4% (95% confidence interval [CI]: 7.2% to 12.1%; P < 0.0001). PLs were more common among obese than nonobese individuals (34.5%, 95% CI: 17.9% to 5l.3% vs. 8%, 95% CI: 5.9% to 10.6%, respectively; P < 0.0001) and those with preexisting dorsocervical fat pads, commonly called "buffalo humps" (BHs) (18.5%, 95% CI: 12.7% to 25.4% vs. 6.1%, 95% CI: 4.03% to 8.83%, respectively, P < 0.0001; relative risk = 3.02, 95% CI: 1.84% to 4.96%, P < 0.0001). The PL prevalence in the nonobese HIV-infected population (body mass index [BMI] <30, n = 550) was 8.0% (95% CI: 5.9% to 10.6%; P < 0.0001). Logistic regression analyses identified the following factors as associated with a greater likelihood for PL: BMI >30 (beta = 0.18, SE = 0.04; P < 0.001), female gender (beta = 1.06, SE = 0.31; P < 0.001), and shorter duration of HIV infection (beta = -0.005, SE = 0.003; P = 0.04). We used a chain graph model to evaluate risk factors for BH and PL simultaneously. A nonnull interaction between these entities was evident, and this association seemed to be independent of factors positively associated with both (BMI and gender).

CONCLUSIONS

PL is a newly recognized manifestation of HIV-associated lipoaccumulation that is more likely to occur among those with coexisting dorsocervical fat pads, suggesting the possibility of a common pathogenesis between the 2 entities. Likewise, PLs are more common among women, obese individuals, and those with a shorter duration of HIV infection. We suggest that PL should be considered part of the HIV-associated lipodystrophy syndrome.

Effects of protease inhibitors on glucose tolerance, lipid metabolism, and body composition in children and adolescents infected with human immunodeficiency virus

OBJECTIVE

To evaluate the effects of protease inhibitors (PIs) as antiretroviral therapy in comparison with other antiretroviral (non-PI) medications on glucose tolerance, lipid metabolism, and body fat distribution in human immunodeficiency virus (HIV)-infected young patients.

METHODS

We conducted a cross-sectional clinical study in an outpatient HIV clinic. The study population consisted of 21 patients (15 female and 6 male) who had had at least 6 months of antiretroviral treatment. The mean age of the patients was 11.9 years (range, 6 to 16.5).

RESULTS

Fifteen patients treated with PIs and 6 patients treated with non-PIs were enrolled in the study. We found no significant differences in the lipid panel and insulin resistance, as determined by using the Quantitative Insulin Sensitivity Check Index formula, in the PI group in comparison with the non-PI group. Lipodystrophy was observed in 47% (7 of 15) of the PI group and 33% (2 of 6) of the non-PI group (P = 0.66). In the presence of lipodystrophy, serum triglyceride levels were higher in the PI group than in the non-PI group (P = 0.046). No such difference was found between the treatment groups when no lipodystrophy was present. There was no significant difference in insulin resistance between the treatment groups in the presence or absence of lipodystrophy.

CONCLUSION

Our study found the presence of lipodystrophy in HIV-infected young patients regardless of whether they were taking PIs or not. In the patients who had lipodystrophy, those treated with PIs had higher serum triglyceride levels than those not treated with PIs.

Fat distribution in women with HIV infection

OBJECTIVE

Both peripheral fat loss and central fat gain have been reported in women with HIV infection. We determined the fat changes that are specific to HIV infection in women.

METHODS

HIV-infected and control women from the study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM) were compared. Lipoatrophy or lipohypertrophy was defined as concordance between participant report of fat change and clinical examination. Whole-body magnetic resonance imaging measured regional adipose tissue volumes. The relationship among different adipose tissue depots was assessed. Factors associated with individual depots were analyzed using multivariate linear regression.

RESULTS

HIV-infected women reported more fat loss than controls in all peripheral and most central depots. Peripheral lipoatrophy was more frequent in HIV-infected women than controls (28% vs. 4%, P < 0.001), whereas central lipohypertrophy was similar (62% vs. 63%). Among HIV-infected women, those with central lipohypertrophy were less likely to have peripheral lipoatrophy (odds ratio, 0.39; 95% confidence interval, 0.20 to 0.75, P = 0.006) than those without central lipohypertrophy. On magnetic resonance imaging, HIV-infected women with clinical peripheral lipoatrophy had less subcutaneous adipose tissue (SAT) in peripheral and central sites and less visceral adipose tissue (VAT) than HIV-infected women without peripheral lipoatrophy. Compared with controls, HIV-infected women had less SAT in the legs, regardless of the presence or absence of lipoatrophy. However, those without lipoatrophy had more VAT and upper trunk SAT than controls. Use of the antiretroviral drug stavudine was associated with less leg SAT but was not associated with VAT. The use of highly active antiretroviral therapy, however, was associated with more VAT.

CONCLUSIONS

Peripheral lipoatrophy occurs commonly in HIV-infected women but is not associated with reciprocally increased VAT or trunk fat.

Identification of omentin as a novel depot-specific adipokine in human adipose tissue: possible role in modulating insulin action

Central (visceral) obesity is more closely associated with insulin resistance, type 2 diabetes, and cardiovascular disease than is peripheral [subcutaneous (sc)] obesity, but the underlying mechanism for this pathophysiological difference is largely unknown. To understand the molecular basis of this difference, we sequenced 10,437 expressed sequence tags (ESTs) from a human omental fat cDNA library and discovered a novel visceral fat depot-specific secretory protein, which we have named omentin. Omentin ESTs were more abundant than many known adipose genes, such as perilipin, adiponectin, and leptin in the cDNA library. Protein sequence analysis indicated that omentin mRNA encodes a peptide of 313 amino acids, containing a secretory signal sequence and a fibrinogen-related domain. Northern analysis demonstrated that omentin mRNA was predominantly expressed in visceral adipose tissue and was barely detectable in sc fat depots in humans and rhesus monkeys. Quantative real-time PCR showed that omentin mRNA was expressed in stromal vascular cells, but not fat cells, isolated from omental adipose tissue, with >150-fold less in sc cell fractions. Accordingly, omentin protein was secreted into the culture medium of omental, but not sc, fat explants. Omentin was detectable in human serum by Western blot analysis. Addition of recombinant omentin in vitro did not affect basal but enhanced insulin-stimulated glucose uptake in both sc (47%, n = 9, P = 0.003) and omental (approximately 30%, n = 3, P < 0.05) human adipocytes. Omentin increased Akt phosphorylation in the absence and presence of insulin. In conclusion, omentin is a new adipokine that is expressed in omental adipose tissue in humans and may regulate insulin action.

Fat distribution in men with HIV infection

OBJECTIVE

Both peripheral fat loss and central fat gain have been reported in HIV infection. Which changes are specific to HIV were determined by comparison with control subjects and the associations among different adipose tissue depots were determined.

METHODS

Cross-sectional analysis of HIV-positive and control men from the study of Fat Redistribution and Metabolic Change in HIV Infection. Lipoatrophy or lipohypertrophy was defined as concordance between participant report of change and examination. Regional adipose tissue volume was measured by magnetic resonance imaging (MRI).

RESULTS

HIV-positive men reported more fat loss than controls in all peripheral and most central depots. Peripheral lipoatrophy was more frequent in HIV-positive men than in controls (38.3% vs. 4.6%, P < 0.001), whereas central lipohypertrophy was less frequent (40.2% vs. 55.9%, P = 0.001). Among HIV-positive men, the presence of central lipohypertrophy was not positively associated with peripheral lipoatrophy (odds ratio = 0.71, CI: 0.47 to 1.06, P = 0.10). On MRI, HIV-positive men with clinical peripheral lipoatrophy had less subcutaneous adipose tissue (SAT) in peripheral and central sites and less visceral adipose tissue (VAT) than HIV-positive men without peripheral lipoatrophy. HIV-positive men both with and without lipoatrophy had less SAT than controls, with legs and lower trunk more affected than upper trunk. Use of the antiretroviral drugs stavudine or indinavir was associated with less leg SAT but did not appear to be associated with more VAT; nevirapine use was associated with less VAT.

CONCLUSION

Both peripheral and central subcutaneous lipoatrophy was found in HIV infection. Lipoatrophy in HIV-positive men is not associated with reciprocally increased VAT.

Lipodystrophy Syndrome: The Morphologic and Metabolic Effects of Antiretroviral Therapy in HIV Infection

Widespread use of highly active antiretroviral therapy (HAART) to manage HIV infection is now associated with the development of lipodystrophy syndrome. This syndrome is a combination of such morphologic and metabolic changes as hyperlipidemia, fat redistribution, and insulin resistance. Although many of the long-term effects of HAART have not been fully recognized, it is thought that lipodystrophy syndrome may now contribute to early-onset hypercholesterolemia, heart disease, and diabetes, and may have a negative psychological impact on the individual living with HIV infection.

Agreement analysis of variables involved in lipodystrophy syndrome definition in HIV-infected patients

BACKGROUND

Lipodystrophy studies in HIV-infected patients have usually defined abnormalities in body fat by clinical evaluation and patient questionnaires. Despite the risk for bias with these subjective approaches, agreement analysis among the large number of variables employed was seldom performed.

OBJECTIVE

To analyze consistency between the usual approaches for definition of abnormalities in body fat distribution.

DESIGN

We evaluated agreement between the clinical and questionnaire findings for abnormalities in body fat in an HIV patient population under antiretroviral treatment followed in our institution, using different criteria for definitions of body fat abnormalities within the same data set.

METHODS

Kappa analysis for consistency and receiver-operator characteristic (ROC) curve analysis were performed.

RESULTS

Low levels of agreement between clinical and patient perspectives were observed. Only one combination of criteria showed adequate agreement results. The waist/hip ratio showed low levels of agreement with all other variables, and no clear discriminative point was observed by ROC curve analysis. The ratio between the trunk fat content and the leg fat content assessed by dual energy x-ray absorptiometry (DEXA) scan demonstrated better agreement and more clear discriminative values for both male and female patients.

CONCLUSION

Agreement analyses may help in the selection of the subjective variable methodology and in the inclusion of consistent and nonredundant objective measurements for diagnosis of abnormalities in body fat.

Antiretoviral Therapy and the Lipodystrophy Syndrome, Part 2: Concepts in Aetiopathogenesis

Clinical research has indicated that the use of nucleoside reverse transcriptase inhibitor (NRTI) and HIV protease inhibitor (PI) therapy is associated with a risk of long-term toxicity syndromes, and that the aetiopathogenesis of these adverse effects is independent of the antiretroviral effects of these drugs. In relation to the lipodystrophy syndrome, it appears that the most powerful determinant of subcutaneous fat wasting is an interaction between these two drug classes. In this review, possible mechanisms underlying the contributions of both PI and NRTI drugs are reviewed, with an emphasis on their effects on adipose tissue. On this basis, an ‘adipocentric’, or minimal model of the syndrome is developed, in which divergent effects at the adipocyte of NRTIs (mitochondrial toxicity) and PIs (insulin resistance and impaired adipocyte maturation) interact to produce a phenotype that is consistent with clinical observations.