Relationship of fat distribution with adipokines in human immunodeficiency virus infection

Human Immunodeficiency Virus Is Associated With Elevated FibroScan-Aspartate Aminotransferase (FAST) Score

BACKGROUND

Whether human immunodeficiency virus (HIV) infection is associated with the development of nonalcoholic steatohepatitis (NASH) remains unclear. The FibroScan-aspartate aminotransferase (FAST) score was developed to identify patients who have histologic NASH with high nonalcoholic fatty liver disease activity score (NAS ≥4) and significant liver fibrosis (≥F2), which has been associated with higher risk of end-stage liver disease. We examined whether HIV infection is associated with elevated FAST score in a large United States (US) cohort.

METHODS

Vibration-controlled transient elastography was performed in 1309 women without history of chronic viral hepatitis enrolled from 10 US sites: 928 women with HIV (WWH) and 381 women without HIV (WWOH). We used multivariable logistic regression to evaluate associations of HIV, demographic, lifestyle, and metabolic factors with an elevated (>0.35) FAST score.

RESULTS

Median age of WWH and WWOH was 51 years and 48 years, respectively. Most (90%) WWH were on antiretroviral therapy and 72% had undetectable HIV RNA. Prevalence of elevated FAST score was higher among WWH compared to WWOH (6.3% vs 1.8%, respectively; P = .001). On multivariable analysis, HIV infection was associated with 3.7-fold higher odds of elevated FAST score (P = .002), and greater waist circumference (per 10 cm) was associated with 1.7-fold higher odds (P < .001). In analysis limited to WWH, undetectable HIV RNA and current protease inhibitor use were independently associated with lower odds of elevated FAST score.

CONCLUSIONS

Our findings suggest that HIV is an independent risk factor for NASH with significant activity and fibrosis. Studies validating FAST score in persons with HIV are warranted.

Immune Dysregulation in Myocardial Fibrosis, Steatosis, and Heart Failure: Current Insights from HIV and the General Population

PURPOSE OF REVIEW

HIV is an independent risk factor for heart failure (HF). Cardiac imaging studies in people with HIV (PWH) have identified myocardial pathologies, namely fibrosis and steatosis, that likely contribute to the higher risk of HF. In this review, we survey existing epidemiological, clinical, and mechanistic literature to identify potential pathways that may contribute to the burden of myocardial fibrosis and steatosis among PWH.

RECENT FINDINGS

Multiple cohort studies over the past 20 years have demonstrated a roughly 2-fold higher risk of incident HF in PWH, as well as a disproportionate burden of myocardial fibrosis and steatosis in PWH without HF. Both myocardial fibrosis and steatosis are known contributors to HF in adults without HIV. Pathways involving the NLRP3 inflammasome, TGF-β1, and adipocyte dysfunction are known to play a crucial role in the development of myocardial fibrosis and steatosis. Upregulation of these pathways in HIV due to direct effects of viral proteins, persistent immune dysregulation, gut epithelial breakdown and dysbiosis, and toxicities from antiretroviral therapy may contribute to myocardial dysfunction in HIV. Understanding these pathways may lead to more precise diagnostic and therapeutic targets to curb HF in PWH. During the past three decades, observational and mechanistic studies have provided important insights into risk factors and pathways that may contribute to the increased HF risk in PWH. Future work is needed to characterize these pathways more precisely in mechanistic studies of PWH, with the goal of ultimately deriving valuable targets for prevention, early diagnosis, and treatment of HF in PWH.

Presumed Nonalcoholic Fatty Liver Disease Among Medicare Beneficiaries With HIV, 2006-2016

Background

Newer treatments for HIV and hepatitis C virus (HCV) have decreased mortality in HIV/HCV patients. Nonalcoholic fatty liver disease (NAFLD) has increased globally; therefore, the prevalence and mortality of NAFLD among HIV (+) patients was assessed.

Methods

Using Medicare denominator, inpatient, and outpatient files (random 5% sample per year), serial cross-sectional analysis (2006 to 2016) was performed. Joinpoint trend analysis evaluated prevalence and mortality with average annual percent change (AAPC). HIV (+) patients and liver diseases (LDs) were identified using International Classification of Diseases 9/10 codes. NAFLD was presumed using diagnosis codes or codes for metabolic dysfunction and obesity in absence of other LDs. Liver-related HIV (+) indicated HIV (+) patients with LDs.

Results

Among 28 675 887 Medicare beneficiaries, 47 062 were HIV (+) (mean [SD] age, 51.4 [11.3] years); 11 920 had liver diseases (6923 HCV, 2019 hepatitis B virus [HBV], 2472 presumed NAFLD, 278 alcoholic liver disease [ALD], and 1653 other LDs); 2882 HIV (+) patients died; 1260 had LDs. The prevalence and mortality for non-liver-related HIV (+) decreased (AAPC, –1.1% and –9.1%). Liver-related HIV (+) increased (AAPC, 1.7%; P = .007); mortality leveled off. Prevalence and mortality worsened for presumed NAFLD (AAPC, 9.7% and 10.0%) and improved for HBV and HCV (HBV: AAPC, –3.5% and –8.8%; HCV: AAPC, –0.7% and –4.9%). After adjustments, HCV (odds ratio [OR], 2.00; 95% confidence interval [CI], 1.24–172), HBV (OR, 2.40; 95% CI, 2.09–2.77), ALD (OR, 5.70; 95% CI, 4.34–7.48), and presumed NAFLD (OR, 1.46; 95% CI, 1.24–1.72) increased 1-year mortality.

Conclusions

Among HIV (+) subjects, viral hepatitis remains the leading LD for increased 1-year mortality, but the prevalence and mortality with presumed NAFLD are increasing.

C1q/TNF-Related Proteins, HIV and HIV-Associated Factors, and Cardiometabolic Phenotypes in Middle-Aged Women

C1q/tumor necrosis factor (TNF)-related proteins (CTRPs) have been linked to energy homeostasis and vascular health. People with HIV are susceptible to cardiometabolic disease, but the contributions of different CTRPs are unknown. We investigated the associations of HIV and related factors with serum CTRPs, and CTRPs' relationships with cardiometabolic phenotypes. This involved a cross-sectional analysis of participants in the Women's Interagency HIV Study aged ≥35 with (n = 209) and without (n = 92) HIV who underwent carotid ultrasound in 2004-2005 and had stored serum available for measurement of total adiponectin and CTRPs 1, 3, 5, and 9. The Benjamini/Hochberg procedure was used to control the study-wide false-positive rate. HIV-positive women had significantly higher adiponectin than HIV-negative women after adjustment for sociodemographic, behavioral, and clinical variables [beta = 0.29 (95% confidence interval 0.11-0.47)]. Among HIV-positive women, lower CD4 count was associated with higher adiponectin and history of AIDS with higher CTRP9, but these were only nominally significant. There was no relationship between HIV status and CTRP 1, 3, or 5, nor was antiretroviral therapy or viral load associated with any CTRP. In the entire cohort, higher adiponectin was associated with significantly lower fasting glucose and insulin resistance, while higher CTRP5 [beta = -0.02 (-0.033 to -0.007)]-and, at a nominal level, CTRPs 1 and 3-was associated with significantly lower carotid intima-media thickness. In conclusion, in this sample of middle-aged women, HIV serostatus was positively associated with adiponectin, but not CTRPs. In turn, serum adiponectin was inversely associated with glucose dysregulation, whereas CTRP5 was inversely associated with carotid intima-media thickness. Further research is needed to determine CTRPs' role in atherosclerosis.

Obesity and Fat Metabolism in Human Immunodeficiency Virus-Infected Individuals: Immunopathogenic Mechanisms and Clinical Implications

Metabolic complications relating to complex effects of viral and immune-mediated mechanisms are now a focus of clinical care among persons living with human immunodeficiency virus (PLHIV), and obesity is emerging as a critical problem. To address knowledge gaps, the US National Institutes of Health sponsored a symposium in May 2018 entitled "Obesity and Fat Metabolism in HIV-infected Individuals." Mechanisms relating to adipose dysfunction and fibrosis, immune function, inflammation, and gastrointestinal integrity were highlighted as contributors to obesity among PLHIV. Fibrotic subcutaneous adipose tissue is metabolically dysfunctional and loses its capacity to expand, leading to fat redistribution, including visceral obesity and ectopic fat accumulation, promoting insulin resistance. Viral proteins, including viral protein R and negative regulatory factor, have effects on adipogenic pathways and cellular metabolism in resident macrophages and T cells. HIV also affects immune cell trafficking into the adipose compartments, with effects on adipogenesis, lipolysis, and ectopic fat accumulation. Key cellular metabolic functions are likely to be affected in PLHIV by gut-derived cytokines and altered microbiota. There are limited strategies to reduce obesity specifically in PLHIV. Enhancing our understanding of critical pathogenic mechanisms will enable the development of novel therapeutics that may normalize adipose tissue function and distribution, reduce inflammation, and improve insulin sensitivity in PLHIV.

Relationships Between Adipose Mitochondrial Function, Serum Adiponectin, and Insulin Resistance in Persons With HIV After 96 Weeks of Antiretroviral Therapy

OBJECTIVE

Some antiretroviral therapy (ART) and HIV itself confer metabolic risk, perhaps through altered mitochondrial function and adipokines. In AIDS Clinical Trials Group study A5224s, adipose mitochondrial DNA (mtDNA) levels decreased on ART, and electron transport chain complex I (CI) and complex IV (CIV) activity decreased. Another study found decreased serum adiponectin on ART with mtDNA mutation m.10398A>G. We hypothesized that decreased adipose tissue mitochondrial function would be associated with lower adiponectin and insulin sensitivity on ART, and m.10398G would influence these changes.

DESIGN

Retrospective analysis of an ART-naive substudy population from A5224s.

METHODS

Analyses included adipose mtDNA levels, CI and CIV activity by immunoassay, visceral adipose tissue by computed tomography, and fasting serum glucose at week 0 and week 96 of ART. Fasting insulin and adiponectin were measured from cryopreserved serum using multiplex bead array. Homeostasis model assessment-2 (HOMA2)-IR and HOMA2-%B estimated insulin resistance and β-cell function, respectively. The m.10398A>G mtDNA variant was available from existing genetic data.

RESULTS

Thirty-seven participants had adipose biopsies at week 0 and week 96. Percent decreases in CIV activity and adiponectin were correlated (Spearman rho 0.41; P = 0.01); this association persisted after controlling for age, sex, body mass index, or visceral adipose tissue in single-covariate regression. HOMA2-IR correlated with decreased CIV (-0.44; P = 0.01) and CI (-0.34; P = 0.05) activity. Among 12 non-Hispanic white persons, m.10398G was associated with decreased adiponectin (P = 0.04).

CONCLUSIONS

Decreased adipose mitochondrial activity correlated with changes in adiponectin and glucose homeostasis on ART. Previous findings that a mtDNA mutation modulates adiponectin levels in persons with HIV were replicated.

The Impact of Weight Gain During HIV Treatment on Risk of Pre-diabetes, Diabetes Mellitus, Cardiovascular Disease, and Mortality

Since the introduction of combined antiretroviral therapy (cART) and more effective treatments for AIDS, there has been a dramatic shift from the weight loss and wasting that characterised HIV/AIDS (and still does in countries where cART is not readily available or is initiated late) to healthy weight, or even overweight and obesity at rates mirroring those seen in the general population. These trends are attributable to several factors, including the "return to health" weight gain with reversal of the catabolic effects of HIV-infection following cART-initiation, strategies for earlier cART-initiation in the course of HIV-infection which have prevented many people living with HIV-infection from developing wasting, in addition to exposure to the modern obesogenic environment. Older cART regimens were associated with increased risk of body fat partitioning disorders (lipodystrophy) and cardiometabolic complications including atherothrombotic cardiovascular disease (CVD) and diabetes mellitus. Whilst cART now avoids those medications implicated in causing lipodystrophy, long-term cardiometabolic data on more modern cART regimens are lacking. Longitudinal studies show increased rates of incident CVD and diabetes mellitus with weight gain in treated HIV-infection. Abdominal fat gain, weight gain, and rising body mass index (BMI) in the short-term during HIV treatment was found to increase incident diabetes risk. Rising BMI was associated with increased risk of incident CVD, however the relationship varied depending on pre-cART BMI category. In contrast, a protective association with mortality is evident, predominantly in the underweight and in resource-poor settings, where weight gain reflects access to cART and virological suppression. The question of how to best evaluate, manage (and perhaps constrain) weight gain during HIV treatment is of clinical relevance, especially in the current climate of increasingly widespread cART use, rising overweight, and obesity prevalence and growing metabolic and cardiovascular disease burden in people living with HIV-infection. Large prospective studies to further characterise the relationship between weight gain during HIV treatment and risk of diabetes, CVD and mortality are required.

Correlation of Leptin, Adiponectin, and Resistin Levels in Different Types of Lipodystrophy in HIV/AIDS Patients

BACKGROUND

Leptin, adiponectin, and resistin may play an important role in the development of lipodystrophy (LD) in HIV/AIDS patients. The aim of this study was to correlate levels of leptin, adiponectin, and resistin between HIV/AIDS patients with LD and without lipodystrophy (non-LD), as well as between subgroups of LD [lipoatrophy (LA), lipohypertrophy (LH), and mixed fat redistribution (MFR)] and non-LD patients.

METHODS

Cross-sectional study of 66 HIV/AIDS patients. Serum levels of leptin, adiponectin, and resistin were measured. The associations between adipocytokine levels and metabolic variables were estimated by Spearman correlation. Analysis of covariance with bootstrapping method was used to examine the relationship between adiponectin and leptin and lipodystrophy categories.

RESULTS

The LD was observed in 29 (44%) patients, while 15 (52%) of them had LA, 4 (14%) had LH, and 10 (34%) patients had MFR. No significant differences regarding leptin, adiponectin, and resistin levels, between LD and non-LD patients, were observed. LH patients had significantly higher levels of leptin and adiponectin in comparison with non-LD patients (P = 0.039, P = 0.011, respectively). Within the LD group, LA patients had significantly lower levels of leptin (LA vs. LH, P = 0.020; LA vs. MFR, P = 0.027), while LH patients had significantly higher levels of adiponectin (LH vs. LA, P = 0.027; LH vs. MFR, P = 0.028). Correlation of adiponectin with LD remains significant in the LH subgroup after adjustment for age, body mass index, cystatin-C, plasminogen activator inhibitor-1 (PAI-1), and interferon gamma (IFN-γ) (P = 0.001).

CONCLUSIONS

Adiponectin and leptin levels differ significantly between LH patients and non-LD patients, as well as between the LD subgroups. Adiponectin may be a more useful marker of LD in HIV/AIDS patients.

Oral Glucose Tolerance Testing identifies HIV+ infected women with Diabetes Mellitus (DM) not captured by standard DM definition

OBJECTIVE

HIV-infected (HIV+) individuals may have differential risk of diabetes mellitus (DM) compared to the general population, and the optimal diagnostic algorithm for DM in HIV+ persons remains unclear. We aimed to assess the utility of oral glucose tolerance testing (OGTT) for DM diagnosis in a cohort of women with or at risk for HIV infection.

METHODS

Using American Diabetic Association DM definitions, DM prevalence and incidence were assessed among women enrolled in the Women's Interagency HIV Study. DM was defined by 2-hour OGTT ≥ 200 mg/dL (DM_OGTT) or a clinical definition (DM_C) that included any of the following: (i) anti-diabetic medication use or self-reported DM confirmed by either fasting glucose (FG) ≥126 mg/dL or HbA1c ≥ 6.5%, (ii) FG ≥ 126 mg/dL confirmed by a second FG ≥ 126 mg/dL or HbA1c 6.5%, or (iii) HbA1c 6.5% confirmed by FG ≥ 126 mg/dL cohort.

RESULTS

Overall, 390 women (285 HIV+, median age 43 years; 105 HIV-, median age 37 years) were enrolled between 2003-2006. Over half of all women were African American. Using DM_C, DM prevalence rates were 5.6% and 2.8% among HIV+ and HIV- women, respectively. Among HIV+ women, adding DM_OGTT to DM_C increased DM prevalence from 5.6% to 7.4%, a 31% increase in the number of diabetes cases diagnosed (p=0.02). In HIV- women, no additional cases were diagnosed by DM-OGTT.

CONCLUSION

In HIV+ women, OGTT identified DM cases that were not identified by a standardized clinical definition. Further investigation is needed to determine whether OGTT should be considered as an adjunctive tool for DM diagnosis in the setting of HIV infection.

Reductions in Plasma Cystatin C After Initiation of Antiretroviral Therapy Are Associated With Reductions in Inflammation: ACTG A5224s

BACKGROUND

Among patients with HIV infection, changes in the kidney filtration marker cystatin C after initiation of antiretroviral therapy (ART) may be related to changes in body composition or biomarkers of inflammation.

METHODS

ACTG A5224s was a substudy of A5202, which randomly assigned ART-naive HIV-infected subjects to blinded abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC) with open-label efavirenz (EFV) or ritonavir-boosted atazanavir. This analysis explored changes in cystatin C from 0 to 96 weeks.

RESULTS

Of the 269 subjects, 85% were male and 66% white non-Hispanics; baseline mean CD4 count was 236 cells per cubic millimeter and cystatin C was 0.89 mg/L. Cystatin C decreased significantly within each arm; however, ritonavir-boosted atazanavir attenuated the beneficial effects of ART on cystatin C compared to EFV. Compared to ABC/3TC, TDF/FTC led to a marginally significant attenuation for percent change analyses only. Higher baseline body mass index and HIV RNA were associated with larger reductions in cystatin C in multivariable models. At baseline, cystatin C was positively correlated with high-sensitivity C-reactive protein (Spearman r = 0.25), interleukin 6 (r = 0.34), soluble intercellular adhesion molecule (r = 0.36), soluble vascular cell adhesion molecule (r = 0.54), tumor necrosis factor α (r = 0.57), and soluble TNF-α receptor I (r = 0.70, all P < 0.001). Reductions in cystatin C from 0 to 96 weeks correlated with reductions in all inflammatory biomarkers (r = 0.39-0.58, P < 0.001) except for high-sensitivity C-reactive protein (r = 0.01, P = 0.89) and IL-6 (r = 0.08, P = 0.24).

CONCLUSIONS

The beneficial effect of ART on cystatin C concentrations is attenuated by boosted ATV when compared to EFV. Reductions in cystatin C after ART are associated with reductions in systemic inflammation.

Comparison of body composition changes between atazanavir/ritonavir and lopinavir/ritonavir each in combination with tenofovir/emtricitabine in antiretroviral-naïve patients with HIV-1 infection

BACKGROUND AND OBJECTIVE

Antiretroviral drug regimen choice may influence changes in body composition. The objective of this study was to compare changes in body composition between ritonavir-boosted atazanavir (ATV/r) and ritonavir-boosted lopinavir (LPV/r) over 96 weeks using data from a substudy of CASTLE, which compared once-daily ATV/r with twice-daily LPV/r, both in combination with tenofovir disoproxil fumarate/emtricitabine in treatment-naïve patients with HIV-1 infection.

METHODS

We examined 224 patients (125 on ATV/r; 99 on LPV/r) at baseline, 48 and 96 weeks using dual-energy X-ray absorptiometry and computerised tomography.

RESULTS

In the lowest baseline body mass index (BMI) group, there were significantly greater gains at week 96 for ATV/r than for LPV/r in subcutaneous adipose tissue and in visceral adipose tissue (VAT). By week 96, patients with lowest baseline CD4 cell counts on ATV/r had 28 % increases in VAT versus 14 % reductions for patients receiving LPV/r. Those with the lowest baseline BMI on ATV/r had 19 % increases in VAT versus reductions of 5 % for patients on LPV/r. In the highest baseline BMI group, the mean increase in triglycerides was 6 and 70 % in the ATV/r and LPV/r arms, respectively. Compared with baseline, an increase in proportion of patients with high waist circumference (WC)/high triglycerides at 96 weeks was noted in both treatment arms, but this increase was numerically greater with LVP/r (18 %) than with ATV/r (11 %).

CONCLUSION

Truncal fat gains on ATV/r primarily led to increases in WC, which may reflect return to health, while on LPV/r increases in WC and triglycerides occurred. Changes in body composition with antiretroviral therapy are influenced by treatment choice and baseline characteristics.

The association of adiposity with kidney function decline among HIV-infected adults: findings from the Fat Redistribution and Metabolic Changes in HIV Infection (FRAM) study

OBJECTIVES

The aim of the study was to investigate the association of adiposity with longitudinal kidney function change in 544 HIV-infected persons in the Study of Fat Redistribution and Metabolic Change in HIV infection (FRAM) cohort over 5 years of follow-up.

METHODS

The regional distribution of muscle and adipose tissue was quantified by whole-body magnetic resonance imaging (MRI), and total adiponectin and leptin levels were measured in serum. Kidney function was assessed using the estimated glomerular filtration rate from serum cystatin C (eGFRCys), obtained at baseline and follow-up. Rapid kidney function decline was defined as annual loss of eGFRCys ≥ 3 mL/min/1.73 m(2) , and incident chronic kidney disease (CKD) was defined as eGFRCys <60 mL/min/1.73 m(2) . Multivariate regression analysis was adjusted for age, race, gender, glucose, antihypertensive use, serum albumin, baseline and change in HIV viral load.

RESULTS

At baseline, mean age was 43 years, mean eGFRCys was 86 mL/min/1.73 m(2) , and 21% of patients had albuminuria. The mean (± standard deviation) eGFRCys decline was -0.11 ± 4.87 mL/min/1.73 m(2) per year; 23% of participants had rapid kidney function decline, and 10% developed incident CKD. The lowest tertile of visceral adipose tissue and the highest tertile of adiponectin were both marginally associated with annual kidney function decline of -0.5 mL/min/1.73 m(2) each, but these associations were not statistically significant after adjustment. We found no statistically significant associations of MRI-measured regional adiposity or serum adipokines with rapid kidney function decline or incident CKD (all P-values>0.1 in adjusted models).

CONCLUSIONS

Contrary to findings in the general population, adiposity did not have a substantial association with longitudinal change in kidney function among HIV-infected persons.

Adipokines, hormones related to body composition, and insulin resistance in HIV fat redistribution syndrome

Background

Lipodystrophies are characterized by adipose tissue redistribution, insulin resistance (IR) and metabolic complications. Adipokines and hormones related to body composition may play an important role linking these alterations. Our aim was to evaluate adipocyte-derived hormones (adiponectin, leptin, resistin, TNF-α, PAI-1) and ghrelin plasma levels and their relationship with IR in HIV-infected patients according to the presence of lipodystrophy and fat redistribution.

Methods

Anthropometric and metabolic parameters, HOMA-IR, body composition by DXA and CT, and adipokines were evaluated in 217 HIV-infected patients on cART and 74 controls. Fat mass ratio defined lipodystrophy (L-FMR) was defined as the ratio of the percentage of the trunk fat mass to the percentage of the lower limb fat mass by DXA. Patient’s fat redistribution was classified into 4 different groups according the presence or absence of either clinical lipoatrophy or abdominal prominence: no lipodystrophy, isolated central fat accumulation (ICFA), isolated lipoatrophy and mixed forms (MXF). The associations between adipokines levels and anthropometric, metabolic and body composition were estimated by Spearman correlation.

Results

Leptin levels were lower in patients with FMR-L and isolated lipoatrophy, and higher in those with ICFA and MXF. Positive correlations were found between leptin and body fat (total, trunk, leg, arm fat evaluated by DXA, and total, visceral (VAT), subcutaneous adipose tissue (SAT), and VAT/SAT ratio evaluated by CT) regardless of FMR-L, and with HOMA-IR only in patients with FMR-L. Adiponectin correlated negatively with VAT, and its mean levels were lower in patients with ICFA and higher in those with no lipodystrophy. Resistin was not correlated with adipose tissue but positively correlated with HOMA-IR in FMR-L patients. PAI-1 levels were higher in MXF-patients and their levels were positively correlated with VAT in those with FMR-L. Ghrelin was higher in HIV-infected patients than controls despite BMI-matching.

Conclusion

The overall body fat reduction in HIV lipoatrophy was associated with low leptin plasma levels, and visceral fat accumulation was mainly associated with decreased plasma levels of adiponectin.

Multiple frequency bioimpedance is an adequate tool to assess total and regional fat mass in HIV-positive patients but not to diagnose HIV-associated lipoatrophy: a pilot study

Introduction

HIV-associated lipodystrophy syndrome causes systemic metabolic alterations and psychological distress that worsen the quality of life of these patients. An early detection should be considered to efficiently treat it. Objective criteria or reference indices are needed for an early diagnosis. Bioelectrical Impedance Analysis (BIA) is an operator-independent, repeatable and non-invasive method of body composition evaluation that is less expensive than dual-energy X-ray absorptiometry (DXA) and/or CT scans. The aims of this pilot study were to validate the data obtained by BIA to measure fat mass in HIV-positive patients with/without lipoatrophy and to determine if BIA correctly diagnoses lipoatrophy in HIV-positive patients.

Methods

Thirty-nine participants were included in this preliminary study. Fourteen were HIV-negative (eight men) whereas 25 were HIV-positive patients (17 men). Eleven of the HIV-positive patients were classified as lipoatrophic according to subjective evaluation by the physicians. Total and regional body composition was measured in basal conditions by DXA and by BIA. To obtain abdominal CT scan fat values, transverse slices with 6-mm thickness were acquired at the L4-L5 intervertebral space.

Results

BIA measurements of total and regional body fat were significantly correlated with those obtained by DXA (p < 0.05 to <0.01) in HIV-positive patients. However, agreement between methods was poor as not very high ICC (intraclass correlation coefficient) values were observed. BIA and DXA showed higher ICC values in lipoatrophic patients. The visceral index obtained by BIA was correlated with total and visceral fat in L4 measured by CT scan (r = 0.607 and r = 0.617, respectively, p < 0.01) in HIV-positive patients. The Fat Mass Ratio (FMR) calculated by BIA did not correlate or agree with DXA values.

Conclusions

Multi-frequency BIA could be an effective method to evaluate the evolution of total and regional fat composition in HIV-positive patients with/without lipoatrophy. The correlations between BIA and DXA improved in lipoatrophic patients and in men, suggesting that its efficacy depends on fat mass, gender and probably other factors. The visceral index obtained by BIA seems to be a reliable indicator of abdominal obesity. However, BIA did not fulfil the need for easy quantitative diagnostic tools for lipoatrophy, and it did not provide sufficient diagnostic cut-off values for this syndrome.

Body composition, soluble markers of inflammation, and bone mineral density in antiretroviral therapy-naive HIV-1-infected individuals

OBJECTIVE

To determine the association among bone mineral density (BMD), inflammatory markers, and alterations in fat and lean mass in untreated HIV-infected individuals.

DESIGN

Cross-sectional analysis of antiretroviral therapy-naive persons enrolled into a randomized clinical trial.

METHODS

Dual-energy x-ray absorptiometry for BMD and lean and fat mass and a laboratory assessment were performed. Soluble biomarkers included adipocytokines (leptin and adiponectin), inflammatory markers (high-sensitivity C-reactive protein and interleukin 6), and markers related to bone metabolism [osteoprotegerin (OPG)], receptor activator of nuclear factor κB ligand. BMD at the lumbar spine, total hip, and femoral neck was expressed as a Z score (number of standard deviations away from age-, race-, and sex-matched reference population).

RESULTS

Three hundred thirty-one subjects had a median (Q1, Q3) age of 36 (28, 45) years, were 89% men, and 44% white. The prevalence of low BMD (Z score ≤ -2 at any of the 3 sites) was 10%. No associations were detected between Z scores and high-sensitivity C-reactive protein, interleukin 6, or receptor activator of nuclear factor κB ligand (P ≥ 0.1). In a linear model adjusting for age, gender, race, and total fat mass, lower lumbar spine Z scores were associated with lower total lean mass, higher serum adiponectin, and lower OPG. Results at the total hip or femoral neck were similar.

CONCLUSIONS

Among antiretroviral therapy-naive HIV-infected individuals, lower BMD was associated with lower lean mass, higher adiponectin, and lower OPG, but not HIV disease variables or any of the inflammatory markers. These findings may have implications for bone metabolism in untreated HIV, in which hypoadiponectinemia and higher OPG may mitigate bone loss.

Adipokines and vascular health in treated HIV infection: an obesity paradox?

We examined the relationship between plasma adipokine concentrations and ultrasound measures of vascular health in 100 HIV-infected adults on antiretroviral therapy. Leptin was positively correlated with flow-mediated dilation of the brachial artery and negatively with carotid intima-media thickness. These relationships were independent of traditional risk factors and trunk fat in women but not men. Neither adiponectin nor resistin was associated with either measure of vascular health.

Relationship of fat distribution with adipokines in patients with acquired immunodeficiency virus infection

BACKGROUND

The aim was to examine the relationship of fat distributions with adipokines concentrations in HIV-infected patients.

METHODS

This was a cross-sectional analysis of 36 HIV (free of lipodystrophy) infected patients. Dual-energy X-ray absorptiometry was used.

RESULTS

In the multivariate analysis, basal adiponectin concentration was a dependent variable, whereas waist to hip ratio and abdominal fat mass were independent predictors in the model (F = 5.1; P < 0.05). Adiponectin concentration decreases by 5.541.2 μg/ml (CI 95%: 8,071.9-3,029.1) for each unit of waist to hip ratio and 561.9 ng/ml (CI 95%: 918.2-213.4) for each kilogram of fat mass of abdominal area. In the multivariate analysis, basal leptin concentration was a dependent variable, whereas waist circumference remained an independent predictor in the model (F = 6.3; P < 0.05), with a direct correlation. Leptin concentration increases by 0.067 ng/ml (CI 95%: 0.001-0.12) for each centimeter of waist circumference.

CONCLUSIONS

Leptin and adiponectin are related with adiposity in HIV-infected patients.

Genes linked to energy metabolism and immunoregulatory mechanisms are associated with subcutaneous adipose tissue distribution in HIV-infected men

OBJECTIVE

Genetic studies may help explain abnormalities of fat distribution in HIV-infected patients treated with antiretroviral therapy (ARV).

METHODS

Subcutaneous adipose tissue (SAT) volume measured by MRI in the leg, the lower trunk, the upper trunk, and the arm was examined in 192 HIV-infected White men, ARV-treated from the Fat Redistribution and Metabolic Change in HIV infection study. Single-nucleotide polymorphisms were assayed using the Illumina Human CNV370-quad beadchip. Multivariate and univariate genome-wide association analyses of the four SAT depots were implemented in PLINK software adjusted for age and ARV duration. Functional annotation analysis using Ingenuity Systems Pathway Analysis tool was carried out for markers with P lower than 10(-3) near known genes identified by multivariate analysis.

RESULTS

Loci (rs10504906, rs13267998, rs921231) in or near the anion exchanger solute carrier family 26, member 7 isoform a (SLC26A7) were strongly associated with the upper trunk and the arm SAT (9.8×10(-7) ≤P<7.8×10(-6)). Loci (rs193139, rs7523050, rs1761621) in and near a gene-rich region including G-protein-signaling modulator 2 (GPSM2) and syntaxin-binding protein 3 (STXBP3) were significantly associated with the lower body SAT depots (9.9×10(-7) ≤P<9.5×10(-6)). GPSM2 is associated with cell division and cancer whereas STXBP3 is associated with glucose metabolism in adipoctyes. Ingenuity Systems Pathway Analysis identified atherosclerosis, mitochondrial function, and T-cell-mediated apoptosis as processes related to SAT volume in HIV-infected individuals (P<5×10(-3)).

CONCLUSION

Our results are limited by the small sample size and replication is needed; however, this genomic scan uncovered new genes associated with metabolism and inflammatory pathways that may affect SAT volume in ARV-treated HIV-infected patients.

Zinc alpha-2 glycoprotein is implicated in dyslipidaemia in HIV-1-infected patients treated with antiretroviral drugs

OBJECTIVES

Treated HIV-1-infected patients with lipodystrophy often develop insulin resistance and proatherogenic dyslipidaemia. Zinc alpha-2 glycoprotein (ZAG) is a recently characterized adipokine which has been shown to be involved in the development of obesity and metabolic syndrome in uninfected subjects. We assessed the relationship between circulating ZAG levels and metabolic derangements in HIV-1-infected patients receiving antiretroviral drugs.

METHODS

Plasma ZAG levels were assessed in 222 individuals: 166 HIV-1-infected patients treated with antiretroviral drugs (77 with lipodystrophy and 89 without lipodystrophy) and 56 uninfected controls. Plasma ZAG levels were assessed by enzyme-linked immunosorbent assay (ELISA) and were correlated with fat distribution abnormalities and metabolic parameters.

RESULTS

HIV-1-infected patients had lower plasma ZAG levels compared with uninfected controls (P < 0.001). No differences were found in ZAG plasma levels according to the presence of lipodystrophy, components of the metabolic syndrome or type of antiretroviral treatment regimen. Circulating ZAG levels were strongly determined by high-density lipoprotein cholesterol (HDLc) in men (B = 0.644; P < 0.001) and showed a positive correlation with total cholesterol (r = 0.312; P < 0.001) and HDLc (r = 0.216; P = 0.005).

CONCLUSIONS

HIV-1-infected patients have lower plasma ZAG levels than uninfected controls. In infected patients, plasma ZAG levels are in close relationship with total cholesterol and HDLc.

Vitamin D in HIV-Infected Patients

Observational studies have noted very high rates of low 25(OH)D (vitamin D) levels in both the general and HIV-infected populations. In HIV-infected patients, low 25(OH)D levels are likely a combination of both traditional risk factors and HIV-specific and antiretroviral therapy-specific contributors. Because of this unique risk profile, HIV-infected persons may be at greater risk for low 25(OH)D levels and frank deficiency and/or may respond to standard repletion regimens differently than HIV-uninfected patients. Currently, the optimal repletion and maintenance dosing regimens for HIV-infected patients remain unknown, as do potential benefits of supplementation that may be unique to the HIV-infected population. This paper reviews data published on HIV infection and vitamin D health in adults over the last year.

Association of increased upper trunk and decreased leg fat with 2-h glucose in control and HIV-infected persons

OBJECTIVE

Changes in body fat distribution and abnormal glucose metabolism are common in HIV-infected patients. We hypothesized that HIV-infected participants would have a higher prevalence of impaired glucose tolerance (IGT) compared with control subjects.

RESEARCH DESIGN AND METHODS

A total of 491 HIV-infected and 187 control participants from the second examination of the Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM) underwent glucose tolerance testing (GTT). Multivariable regression was used to identify factors associated with GTT parameters.

RESULTS

The prevalence of impaired fasting glucose (IFG) (>110 mg/dL) was similar in HIV-infected and control participants (21 vs. 25%, P = 0.23). In those without IFG, the prevalence of IGT was slightly higher in HIV-infected participants compared with control subjects (13.1 vs. 8.2%, P = 0.14) and in HIV+ participants with lipoatrophy versus without (18.1 vs. 11.5%, P = 0.084). Diabetes detected by GTT was rare (HIV subjects 1.3% and control subjects 0%, P = 0.65). Mean 2-h glucose levels were 7.6 mg/dL higher in the HIV-infected participants (P = 0.012). Increased upper trunk subcutaneous adipose tissue (SAT) and decreased leg SAT were associated with 2-h glucose and IGT in both HIV-infected and control participants. Adjusting for adipose tissue reduced the estimated effects of HIV. Exercise, alcohol use, and current tenofovir use were associated with lower 2-h glucose levels in HIV-infected participants.

CONCLUSIONS

In HIV infection, increased upper trunk SAT and decreased leg SAT are associated with higher 2-h glucose. These body fat characteristics may identify HIV-infected patients with normal fasting glucose but nonetheless at increased risk for diabetes.

Leptin and the regulation of body weigh

The cloning of the ob gene and its gene product, leptin, has led to the elucidation of a robust physiologic system that maintains fat stores at a relatively constant level. Leptin is a peptide hormone secreted by adipose tissue in proportion to its mass. Recessive mutations in the leptin gene are associated with massive obesity in mice and humans, establishing a genetic basis for obesity. Leptin circulates in blood and acts on the brain to regulate food intake and energy expenditure. When fat mass falls, plasma leptin levels fall, stimulating appetite and suppressing energy expenditure until fat mass is restored. When fat mass increases, leptin levels increase, suppressing appetite until weight is lost. This system maintains homeostatic control of adipose tissue mass. The discovery of leptin has advanced our understanding of metabolic disease in a number of respects. Its identification has revealed a new endocrine system regulating body weight. This system provides a means by which changes in nutritional state regulate other physiologic systems. A number of leptin deficiency syndromes that are treatable with leptin replacement have been identified. The majority of obese subjects are leptin resistant, which establishes that obesity is the result of hormone resistance. Leptin treatment results in weight loss in a subset of obese patients and can also synergize with other anti-obesity agents to reduce weight in the general population. Leptin provides an entry point for studying a complex human behavior. Finally, this research has established that there is a powerful biological basis for obesity, a fact that is (correctly) changing public perception about the pathogenesis of this medical condition.

Regional fat deposition and cardiovascular risk in HIV infection: the FRAM study

HIV-infected individuals are at increased risk for cardiovascular disease (CVD) and lipodystrophy, but the relationship between regional adipose tissue (AT) depots and CVD risk is not well described. We determined regional AT volumes and CVD risk in an analysis of 586 HIV-infected and 280 control FRAM study subjects using whole-body magnetic resonance imaging (MRI) and the Framingham Risk Score (FRS). Median FRS and FRS >10% were higher in HIV than control men (4.7% vs. 3.7%, p=0.0002; 16% vs. 4%, p<0.0001). HIV and control women had similarly low FRS (1.1% vs. 1.2%, p=0.91). In controls, total AT and all regional AT depots showed strong positive correlations with FRS (p<0.001) in men and weaker positive correlations in women. Greater visceral AT (VAT) and lower leg subcutaneous AT (SAT) volumes were associated with elevated FRS in HIV subjects with a trend for upper trunk SAT. Controls in the lowest quartile of leg SAT had the lowest FRS (1.5%), whereas HIV with similarly low leg SAT had the highest FRS (4.0%, p<0.001 vs. controls). Increased VAT is associated with CVD risk, but the risk is higher in HIV-infected individuals relative to controls at every level of VAT. Peripheral lipoatrophy (as measured by leg SAT) is associated with striking increased CVD risk in HIV-infected patients even after controlling for VAT, whereas low leg SAT is associated with low CVD risk in controls.

Effects of tesamorelin on inflammatory markers in HIV patients with excess abdominal fat: relationship with visceral adipose reduction

OBJECTIVE

To report the effects of tesamorelin, a growth hormone-releasing hormone analogue, on inflammatory and fibrinolytic markers and to relate these effects to changes in visceral adipose tissue (VAT).

DESIGN AND METHODS

Four hundred and ten HIV-infected patients with abdominal adiposity were randomized to 2 mg tesamorelin (n = 273) or placebo (n = 137) subcutaneously daily for 26 weeks. Circulating plasminogen activator inhibitor-1 (PAI-1) antigen, tissue plasminogen activator (tPA) antigen, C-reactive protein (CRP), and adiponectin were assessed.

RESULTS

At baseline, VAT was significantly associated with PAI-1 antigen (ρ = 0.36, P < 0.001), tPA antigen (ρ = 0.29, P < 0.001), CRP (ρ = 0.18, P < 0.001), and adiponectin (ρ = -0.22, P < 0.001). Treatment with tesamorelin resulted in a significant decrease from baseline in tPA antigen (-2.2 ± 2.5 vs. -1.6 ± 2.9 ng/ml, tesamorelin vs. placebo, P < 0.05). Changes in PAI-1 antigen were not significant in the tesamorelin group compared to placebo. Among patients receiving tesamorelin, changes in inflammatory markers were associated with change in VAT (PAI-1 antigen: ρ = 0.16, P = 0.02; tPA antigen: ρ = 0.16, P = 0.02; adiponectin: ρ = -0.27, P < 0.001), and these associations remained significant when controlling for changes in insulin-like growth factor-1.

CONCLUSION

In HIV patients with abdominal adiposity, tesamorelin may have a modest beneficial effect on adiponectin and fibrinolytic markers in association with changes in VAT. Further studies are needed to determine the clinical significance of these changes. These data further highlight the deleterious role of excessive VAT and the utility of strategies to improve VAT in this population.

Adipose tissue biology and HIV-infection

HIV-1/highly active antiretroviral therapy-associated lipodystrophy syndrome (HALS) is an adipose tissue redistribution disorder characterized by subcutaneous adipose tissue lipoatrophy, sometimes including visceral adipose tissue hypertrophy and accumulation of dorsocervical fat ('buffalo hump'). The pathophysiology of HALS appears to be multifactorial and several key pathophysiological factors associated with HALS have been identified. These include mitochondrial dysfunction, adipocyte differentiation disturbances, high adipocyte lipolysis, and adipocyte apoptosis. These alterations in adipose tissue biology expand to involve systemic metabolism through alterations in endocrine functions of adipose tissue (via disturbed adipokine release), enhanced production of pro-inflammatory cytokines and excessive free fatty-acid release due to lipolysis. The deleterious action of some antiretroviral drugs is an important factor in eliciting these alterations in adipose tissue. However, HIV-1 infection-related events and HIV-1-encoded proteins also contribute directly to the complex development of HALS through effects on adipocyte biology, or indirectly through the promotion of local inflammation in adipose tissue.

Molecular mechanisms for insulin resistance in treated HIV-infection

Identification and characterization of the molecular mechanisms contributing to the high incidence of insulin resistance in HIV infected patients treated with combined antiretroviral therapy remains a critically important goal in the quest to improve the safety of antiretroviral treatment regimens. The use of in vitro model systems together with the investigation of drug-mediated effects on glucose homeostasis in animals and healthy human volunteers has provided important insight into the contribution of individual drugs to insulin resistance and affected cellular pathways. HIV protease inhibitor mediated blockade of glucose transport and nucleoside reverse transcriptase inhibitor mediated mitochondrial toxicity have been well characterized. Together with growing understanding of mediators of insulin resistance in non-HIV metabolic syndrome, additional cellular effects including the induction of endoplasmic reticulum and oxidative stress, altered adipocytokine secretion, and lipotoxicity have been integrated into this developing picture. Further elucidation of these mechanisms provides potential for the continued development of safer antiviral drugs and targeted treatment of insulin resistance in affected patients.

Association between HIV replication and serum leptin levels: an observational study of a cohort of HIV-1-infected South African women

Background

Advanced HIV infection can result in lipoatrophy and wasting, even in the absence of ongoing opportunistic infections, suggesting that HIV may directly affect adipose tissue amount and distribution.

Methods

We assessed the relationship of fat (measured using anthropometry, DEXA, MRI scans) or markers related to glucose and lipid metabolism with viral load in a cross-sectional sample of 83 antiretroviral-naïve HIV-1-infected South African women. A multivariable linear model was fitted to log₁₀VL to assess the combined effect of these variables.

Results

In addition to higher T cell activation, women with viral load greater than the population median had lower waist circumference, body mass index and subcutaneous abdominal fat, as well as lower serum leptin. We demonstrate that leptin serum levels are inversely associated with viral replication, independent of the amount of adipose tissue. This association is maintained after adjusting for multiple variables associated with disease progression (i.e., cellular activation and innate immunity effector levels).

Conclusions

Our results demonstrate that serum leptin levels are inversely associated with viral replication, independent of disease progression: we postulate that leptin may affect viral replication.

Regional adipose tissue measured by MRI over 5 years in HIV-infected and control participants indicates persistence of HIV-associated lipoatrophy

OBJECTIVE

Peripheral fat loss and visceral fat gain have been reported in HIV infection. There are limited data on long-term change in adipose tissue in HIV-infected patients vs. controls. Therefore, we determined change in regional adipose tissue from baseline examination to 5 years later among participants in the study of Fat Redistribution and Metabolic Change in HIV Infection.

METHODS

Regional adipose tissue volume was measured using MRI at both examinations in 477 HIV-infected and 214 control men and women. Lipoatrophy was defined as leg subcutaneous adipose tissue (SAT) below the cutoff point marking the lowest decile (10%) of controls at each examination.

RESULTS

HIV-infected and control participants showed similar adipose tissue gains. In men, all SAT depots and visceral adipose tissue started lower and remained lower on average in HIV-infected vs. controls. In women, leg and arm SAT also started lower and remained lower in HIV-infected vs. controls. Mean leg SAT of HIV-infected men was 67% of control men at baseline and 65% at follow-up; for women 83% and 77%. At baseline, 48% of HIV-infected participants had lipoatrophy; on average those with baseline lipoatrophy gained 0.96L of leg SAT compared with 1.23L gain for controls in the lowest decile (P = 0.16). At follow-up, 53% of HIV-infected participants had lipoatrophy. In multivariable models, discontinuation of stavudine appeared to produce little gain in leg SAT ( approximately 1.1%/year).

CONCLUSION

HIV-infected participants did not substantially recover SAT compared with controls, although both showed average gains. HIV-associated lipoatrophy persisted after 5 years of follow-up.

Impact of antiretroviral therapy on growth, body composition and metabolism in pediatric HIV patients

Highly active antiretroviral therapy improves survival and growth in children with HIV infection. However, its use can be associated with adverse changes in body composition and metabolism. Bone mineral density can be adversely affected in HIV-positive children due to nutritional compromise or certain antiretrovirals. HIV-associated lipodystrophy, consisting of redistribution of adipose tissue, insulin resistance, and dyslipidemia, has also been described in children. Pediatric HIV patients may be at greater risk for these problems because of their longer potential lifetime exposure to these agents and because childhood is normally a period of rapid growth and tissue accretion. Healthcare providers for children with HIV infection must be aware of the potential complications associated with HIV antiretrovirals so that their antiviral efficacy can be balanced against their risk for side effects. In this review, we discuss the alterations in childhood growth and body composition that occur in HIV-infected children, and describe the impact of antiretroviral therapy on these outcomes. The problem of HIV-associated lipodystrophy syndrome in children is also discussed. Children with HIV should have their growth and body composition systematically monitored. Antiretroviral regimens should be tailored to optimize adherence and viral suppression while minimizing the potential for adverse side effects.

HIV protease inhibitors and insulin resistance: lessons from in-vitro, rodent and healthy human volunteer models

PURPOSE OF REVIEW

Although the use of HIV protease inhibitors is linked to the development of insulin resistance and other metabolic changes that greatly increase the risk for cardiovascular disease, the molecular mechanisms responsible remain incompletely understood. This review summarizes recent advances that have been made in understanding the relative contributions of individual protease inhibitors to both acute and chronic insulin resistance together with newly identified cellular mediators.

RECENT FINDINGS

Individual protease inhibitors, alone and in combination, have differing propensities to induce insulin resistance, reflecting relative differences in both affinities for identified molecular targets and pharmacokinetic profiles. Several of the most recent protease inhibitors approved for clinical use or in development appear to be less likely to induce insulin resistance. In addition to direct effects on glucose transporter-4 activity, induction of oxidative stress, proteosome inhibition, alteration of adipokine levels, and changes in suppressors of cytokine signaling-1 have been implicated.

SUMMARY

A better understanding of the propensity of individual HIV protease inhibitors to produce insulin resistance will allow the tailoring of individual treatment plans based upon overall risk for diabetes. The elucidation of the molecular mechanisms for alterations in glucose homeostasis will facilitate the development of newer generations of HIV protease inhibitors that maintain their clinical efficacy without contributing to the development of diabetes mellitus and other proatherogenic effects.

HIV viremia and changes in kidney function

OBJECTIVE

To evaluate the effect of HIV infection on longitudinal changes in kidney function and to identify independent predictors of kidney function changes in HIV-infected individuals.

DESIGN

A prospective cohort.

METHODS

Cystatin C was measured at baseline and at the 5-year follow-up visit of the Study of Fat Redistribution and Metabolic Change in HIV infection in 554 HIV-infected participants and 230 controls. Control participants were obtained from the Coronary Artery Risk Development in Young Adults study. Glomerular filtration rate (eGFRcys) was estimated using the formula 76.7 x cysC(-1.19).

RESULTS

Compared with controls, HIV-infected participants had a greater proportion of clinical decliners (annual decrease in eGFRcys > 3 ml/min per 1.73 m2; 18 versus 13%, P = 0.002) and clinical improvers (annual increase in eGFRcys > 3 ml/min per 1.73 m2; 26 versus 6%, P < 0.0001). After multivariable adjustment, HIV infection was associated with higher odds of both clinical decline (odds ratio 2.2; 95% confidence interval 1.3, 3.9, P = 0.004) and clinical improvement (odds ratio 7.3; 95% confidence interval 3.9, 13.6, P < or = 0.0001). Among HIV-infected participants, a decrease in HIV viral load during follow-up was independently associated with clinical improvement; conversely, higher baseline and an increase in viral load during follow-up were associated with clinical decline. No individual antiretroviral drug or drug class appeared to be substantially associated with clinical decline or improvement.

CONCLUSION

Compared with controls, HIV-infected persons were more likely both to have clinical decline and clinical improvement in kidney function during 5 years of follow-up. The extent of viremic control had a strong association with longitudinal changes in kidney function.

Leptin at 14 y of age: an ongoing story

The cloning of the ob gene and its gene product leptin has led to the elucidation of a robust physiologic system that maintains constancy of fat stores. Leptin is a peptide hormone secreted by adipose tissue and regulates adipose tissue mass and energy balance. Recessive mutations in the leptin gene are associated with massive obesity in mice and in some humans, which establishes a genetic basis for obesity. Leptin circulates in blood and acts on the brain to regulate food intake and energy expenditure. When fat mass decreases, plasma leptin concentrations decrease, which stimulates appetite and suppresses energy expenditure until fat mass is restored. When fat mass increases, leptin concentrations increase, which suppresses appetite until weight is lost. This system maintains homeostatic control of adipose tissue mass.

Assessment of ultrasound for use in detecting lipoatrophy in HIV-infected patients taking combination antiretroviral therapy

The aim of this study was evaluation of ultrasound (US) as a tool for the assessment of lipoatrophy in a population of HIV-infected patients. We enrolled a convenience sample of 151 HIV-infected Caucasian participants (males, 79%) who were treated for at least 1 year with combination antiretroviral therapy (CART) in Zagreb, Croatia. US measurements of subcutaneous fat thickness were done over the malar, brachial, and crural region. We determined sensitivity and specificity of US as a diagnostic tool for lipoatrophy using receiver-operating curves and concordant patient and clinician assessment as our reference for the presence of lipoatrophy. HIV was acquired through heterosexual contact in 50% of participants and by sex between men in 42%. The mean current CD4 cell count was 503.1 cells=mm3 (standard deviation [SD] = 250.8). Seventy-seven (51%) participants were treated with stavudine and 91 (64%) with a protease inhibitor for at least 6 months. Nineteen (13%)participants had lipoatrophy in at least one anatomic site. Sensitivity of US ranged from 67%-71%, specificity from 65%-71%, positive and negative predictive values ranged from 11%-20% and 96-97%, respectively. US diagnosed lipoatrophy was more frequently found in patients with a history of stavudine treatment and in females. Patients with lipoatrophy had a longer duration of CART than those without lipoatrophy. US is a useful tool in ruling out the presence of clinical lipoatrophy in patients on CART. Using this objective measure of subcutaneous fat may be useful in helping clinicians make decisions about changing therapy.

Comparison of dual-energy X-ray absorptiometry and magnetic resonance imaging-measured adipose tissue depots in HIV-infected and control subjects

BACKGROUND

Studies in persons without HIV infection have compared adipose tissue measured by dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI), but no such study has been conducted in HIV-infected (HIV+) subjects, who have a high prevalence of regional fat loss.

OBJECTIVE

We compared DXA- with MRI-measured trunk, leg, arm, and total fat in HIV+ and control subjects.

DESIGN

A cross-sectional analysis was conducted in 877 HIV+ subjects and 260 control subjects in FRAM (Study of Fat Redistribution and Metabolic Change in HIV Infection), stratified by sex and HIV status.

RESULTS

Univariate associations of DXA with MRI were strongest for total and trunk fat (r > or = 0.92) and slightly weaker for leg (r > or = 0.87) and arm (r > or = 0.71) fat. The average estimated limb fat was substantially greater for DXA than for MRI for HIV+ and control men and women (all P < 0.0001). Less of a difference was observed in trunk fat measured by DXA and MRI, but the difference was still statistically significant (P < 0.0001). Bland-Altman plots showed increasing differences and variability. Greater average limb fat in control and HIV+ subjects (both P < 0.0001) was associated with greater differences between DXA and MRI measurements. Because the control subjects had more limb fat than did the HIV+ subjects, greater amounts of fat were measured by DXA than by MRI when control subjects were compared with HIV+ subjects. More HIV+ subjects had leg fat in the bottom decile of the control subjects by DXA than by MRI (P < 0.0001).

CONCLUSIONS

Although DXA- and MRI-measured adipose tissue depots correlate strongly in HIV+ and control subjects, differences increase as average fat increases, particularly for limb fat. DXA may estimate a higher prevalence of peripheral lipoatrophy than does MRI in HIV+ subjects.