Plasmatic lipocalin-2 levels in chronic low-grade inflammation syndromes: Comparison between metabolic syndrome, total and partial adult growth hormone deficiency

Lipocalin-2 (LCN2) is a secreted glycoprotein involved in several chronic inflammatory processes. Metabolic syndrome (MetS) and adult growth hormone deficiency (GHD) are known as chronic inflammatory conditions. The primary objective of this observational cross-sectional study was to compare LCN2 plasmatic levels in these clinical settings, whereas the secondary objective was to investigate any possible correlation between LCN2 and BMI and/or indexes of insulin sensitivity/resistance. Seventy-four patients were divided as follows: Group A, MetS (18 patients, 13 females and 5 males, mean +/- SEM age 45.1 +/- 4.11 years, BMI 31.22 +/- 1.73 kg/m(2)); Group B, total GHD (18 patients, 8 females and 10 males, age 52.44 +/- 2.61 years, BMI 30.49 +/- 1.87 kg/m(2)); Group C, Partial GHD (pGHD; 19 patients, 13 females and 6 males, age 48.63 +/- 2.19 years, BMI 29.11 +/- 1.85 kg/m(2)); Group D, Controls (19 patients, 13 females and 6males, age 40.26 +/- 2.87 years, BMI 23.25 +/- 0.95 kg/m(2)). They were evaluated for glucose and insulin, HOMA-index, QUICKI-index, Total/low-density lipoprotein/high-density lipoprotein cholesterol, triglycerides, uric acid, IGF-1, and LCN2. LCN2 plasmatic levels were significantly increased in MetS, while no significant differences with controls were found in total and pGHD. LCN2 levels did not correlate with BMI. A significant positive correlation between LCN2 and HOMA-index was found in controls, while a trend-like, yet not significant, a positive correlation was observed in pGHD. Our data show an increase in LCN2 plasmatic levels in MetS. Different inflammatory patterns characterize MetS and GHD. The correlation between HOMA index and LCN2 in normal subjects and possibly in pGHD ones suggests a modulatory action of LCN2 on insulin resistance.