Insulin-like growth factors, insulin-like growth factor-binding proteins, insulin-like growth factor-binding protein-3 protease, and growth hormone-binding protein in lipodystrophic human immunodeficiency virus-infected patients

Abstract

Human immunodeficiency virus (HIV)-lipodystrophy is associated with impaired growth hormone (GH) secretion. It remains to be elucidated whether insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), IGFBP-3 protease, and GH-binding protein (GHBP) are abnormal in HIV-lipodystrophy. These parameters were measured in overnight fasting serum samples from 16 Caucasian males with HIV-lipodystrophy (LIPO) and 15 Caucasian HIV-infected males without lipodystrophy (NONLIPO) matched for age, weight, duration of HIV infection, and antiretroviral therapy. In LIPO, abdominal fat mass and insulin concentration were increased (>90%, P < .01) and insulin sensitivity (Log10ISI(composite)) was decreased (-50%, P < .001). Total and free IGF-I, IGF-II, IGFBP-3, and IGFBP-3 protease were similar between groups (all P > .5), whereas, in LIPO, IGFBP-1 and IGFBP-2 were reduced (-36%, P < .05 and -50%, P < .01). In pooled groups, total IGF-I, free IGF-I, total IGF-II, and IGFBP-3, respectively, correlated inversely with age (all P < .01). In pooled groups, IGFBP-1 and IGFBP-2 correlated positively with insulin sensitivity (age-adjusted all P < .05). IGFBP-3 protease correlated with free IGF-I in pooled groups (r(p) = 0.47, P < .02), and in LIPO (r(p) = 0.71, P < .007) controlling for age, total IGF-I, and IGFBP-3. GHBP was increased, whereas GH was decreased in LIPO (all P < .05). GH correlated inversely with GHBP in pooled groups (P < .05). Taken together the similar IGFs and IGFBP-3 concentrations between study groups, including suppressed GH, and increased GHBP in LIPO, argue against GH resistance of GH-sensitive tissues in LIPO compared with NONLIPO; however, this notion awaits examination in dose-response studies. Furthermore, our data suggest that IGFBP-3 protease is a significant regulator of bioactive IGF-I in HIV-lipodystrophy.