Relation of leptin pulse dynamics to fat distribution in HIV-infected patients

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.

Lipodystrophy and metabolic syndrome in HIV-infected patients treated with antiretroviral therapy

Lipodystrophy (lipo) and metabolic derangements associated with an increased cardiovascular risk are observed frequently in human immunodeficiency virus (HIV)-infected patients who receive antiretroviral treatment (ART). The objective of the study was to provide detailed biochemical information about metabolic syndrome in this condition. One hundred forty-six HIV-infected male and female patients on ART for more than 6 months were compared with 156 body mass index (BMI)-matched healthy subjects. Lipodystrophy was diagnosed upon patient and physician concordance. Metabolic syndrome was defined according to the Adult Treatment Panel III criteria. Plasma adiponectin (AD) and leptin were measured by radioimmunoassay. Insulin resistance (IR) was assessed by the homeostasis model assessment (HOMA). The prevalence of metabolic syndrome was higher in HIV-infected patients on ART than in non-HIV-infected healthy controls (15.8% vs 3.2%; P < .001). Patients with metabolic syndrome are older (44.6 +/- 6 vs 39.8 +/- 8 years; P = .004), have an increased BMI (24.9 +/- 3.8 vs 22.9 +/- 9.8 kg/m(2); P = .01), present with a reduced AD-to-leptin ratio log(10) (-0.19 +/- 0.4 vs 0.5 +/- 0.4; P = .04), and show increased IR (HOMA, 5.6 +/- 2.7 vs 3.8 +/- 2.2; P = .001; plasma fasting insulin, 22.9 +/- 9.8 vs 16.6 +/- 9.7 ng/mL; P < .001). In multivariate analysis, the diagnosis of lipo and HOMA were independently and significantly related to metabolic syndrome. In conclusion, the prevalence of metabolic syndrome is significantly increased in HIV-infected patients on ART and its presence is associated with lipo, increased age and BMI, IR, and a reduced plasma AD-to-leptin ratio.

Leptin and Adiponectin in the HIV Associated Metabolic Syndrome: Physiologic and Therapeutic Implications

Leptin and adiponectin represent two newly discovered adipose tissue derived hormones with important roles in energy homeostasis and insulin resistance. Their interrelations with the manifestations of the HIV associated metabolic syndrome and specific somatomorphic changes i.e. fat redistribution is reviewed. A synopsis of published studies is presented and the potential role of leptin and adiponectin is discussed. We have described an association of the HIV metabolic syndrome with a state of reduced insulin sensitivity due to adiponectin deficiency. The metabolic syndrome is also accompanied by leptin deficiency in lipoatrophic subjects and possibly by a leptin resistance state in lipohypertrophic patients. Adiponectin and / or leptin therapy in a manner similar to other leptin deficiency states may assist in the future management of such patients.