Adipokine protein expression pattern in growth hormone deficiency predisposes to the increased fat cell size and the whole body metabolic derangements.

Description

This study tested the hypothesis that growth hormone deficiency (GHD) was associated with several metabolic abnormalities within the adipose tissue, such as low-grade inflammation and insulin resistance. Protein arrays of the subcutaneous depot of adipose tissue were obtained and an oral glucose tolerance (OGTT) test was performed in 32 adults (16 with GHD) covering a wide range of adiposity. Body fat distribution and adipocyte size were also measured. The study sample was separated into 2 groups: lean (9 with and 9 without GHD) and obese (7 with and 7 without GHD) subjects. In lean and obese subjects, those with GHD had increased plasma levels of insulin growth factor-1, glucose after 2 hours of the OGTT, and C-reactive protein. In lean individuals, subjects with GHD had higher LDL cholesterol levels, higher subcutaneous and intra-abdominal (visceral) adipose tissue accumulation, and lower in vivo insulin action. These differences were not observed in obese controls and obese subjects with GHD. In both lean and obese subjects, mean adipocyte size was increased in subjects with GHD (93.2 ± 6.7 mm vs. 129.1 ± 6.7 mm, respectively, in lean control and lean GHD subjects and 99.3 ± 5.6 mm vs. 146.2 ± 5.2 mm, respectively, in obese control and obese GHD subjects). Protein arrays revealed that adipose tissue expansion in GHD subjects was associated with a concomitant increase in pro-inflammatory cytokine levels, such as interleukin-1β and interferon-g, and chemoattractant proteins, such as interferon-inducible T cell a-chemoattractant, monocyte chemoattractant protein-2 and -3, and eotaxin. Results of this investigation suggest that GHD-associated dyslipidemia and insulin resistance are likely due to macrophage infiltration of adipose tissue and its associated pro-inflammatory state.