Table 1.
Characteristics of the study participants.
Figure 1.
Plasma levels of OPN and IL-18 in obese individuals.
60 plasma samples from obese (n: 24), overweight (n: 20) and lean individuals (n: 16) were analyzed for expression of the circulating OPN (A) and IL-18 (B). Each dot represents the individual value of OPN and IL-18. Lines represented the mean values of plasma OPN and IL-18 of each group with ± SE.
Figure 2.
Expression of OPN and IL-18 by PBMCs.
Total RNA was extracted from PBMCs of 60 individuals with different BMI (lean: 16; overweight: 20; obese 24). OPN and IL-18 mRNA were measured by real time quantitative PCR. Relative mRNA expression was expressed as fold expression over average of gene expression of lean group. The expression level in lean group was assumed to be 1. Values are presented as mean ± SE (A and B). PBMCs from three donors of each group were cultured in RPMI supplemented with 2% FBS for 16 hours and then culture supernatants were collected. Secreted OPN protein was determined in the culture supernatants by ELISA (C). Data presented were the means of three independent experiments performed with PBMCs of three donors of each group with ± SE.
Figure 3.
Expression of OPN and IL-18 mRNA in adipose tissue.
Adipose tissue samples from 9 (lean: 3, overweight: 3 and obese: 3) individuals with different BMI were subjected to total RNA isolation. OPN and IL-18 mRNA expression was determined by real time quantitative RT-PCR. Relative mRNA expression was expressed as fold expression over average of gene expression of lean group. The expression level in lean group was assumed to be 1. Values are presented as mean ± SE (A and B).
Figure 4.
Linear regression between OPN and IL-18.
Plasma OPN and IL-18 levels were determined by ELISA There was a statistical significant linear regression between OPN and IL-18 (r = 0.52, P = 0.0004, n = 44) in obese and overweight individuals which were free from overweight/obesity induced major complications (A). A strong association of OPN mRNA (Fold change) with IL-18 mRNA was observed in adipose tissue (r = 0.91, P = 0.01: (B). Fold change expression of OPN and IL-18 mRNA in PBMCs of 44 overweight and obese individuals was correlated with each other (r = 0.45, P = 0.0018) (C).
Figure 5.
OPN is expressed by PBMCs and its secretion is induced by rhIL-18.
PBMCs were treated with and without rhIL-18 (20 ng/ml) in the presence or absence of anti IL-18Rα neutralizing monoclonal antibody (0.1 ug/ml), and isotype control antibody IgG1 (0.1 ug/ml). Cells were treated as indicated for 16 hours. PBMCs and culture supernatants were harvested. Total RNA was isolated and OPN gene expression was determined by real time quantitative RT-PCR. Relative mRNA expression was expressed as fold expression over average of gene expression of controls. The average expression level in controls was assumed to be 1. Values are presented as mean ± SE (A). Secreted OPN protein was determined in the culture supernatants by ELISA (B). Data were shown from three independent experiments, each performed with PBMCs derived from three different healthy donors.
Table 2.
Correlation of plasma and PBMC gene expression levels of OPN and IL-18 with metabolic markers.
Table 3.
Multiple stepwise linear regression analysis to identify clinical variables (metabolic parameters) associated with OPN or IL-18 level as a dependent variable.