A Study of Circulating Inflammatory Markers and Adipokines Associated With Obesity

Obesity in adolescents and young adults has increased significantly in recent years resulting in the development of chronic diseases. Obesity induces adipocyte dysfunction, with secretion of adipokines and activation of macrophages leading to inflammatory cytokine production. The aim of the present study was to investigate the relationship between serum levels of adiponectin, leptin, resistin, IL6, CRP and Adiponectin gene expression in young subjects with different BMI groups. Study subjects included 300 over weight, obese males and females with an age ranging from 17 to 30 years. 100 Comparable control subjects with normal BMI were included. The data was stratified on the basis of BMI into normal-weight, overweight, Obese I and obese II groups following the WHO criteria for Asians. Anthropometric parameters including age, BMI, waist circumference, WHR, systolic and diastolic blood pressure were assessed. The metabolic and inflammatory parameters including glucose, Insulin, Lipid profile, Leptin, Adiponectin, Resistin, C-reactive protein and interleukin-6 in serum were measured by chemistry analyzer and ELISA. Insulin resistance was determined by HOMAIR. Adiponectin gene expression was analysed in 100 selected subjects from different BMI groups. RNA extraction was done by TRIZOL method and cDNA synthesis was done by using cDNA synthesis kit. The expression of target gene was compared with GAPDH on Real time PCR using gene specific primers. Statistical analysis was done on SPSS version 13.0. Serum levels of insulin, leptin, resistin, CRP and IL-6 were significantly elevated in overweight and obese subjects as compared to control subjects (p<0.01). Leptin showed significant positive correlation with WHR, HDLc, TChol/HDL ratio, insulin and HOMAIR in overweight group. Resistin was significantly associated with BMI, WHR, fasting glucose, systolic and diastolic blood pressure, Triglycerides, cholesterol, insulin and HOMAIR in overweight and obese groups. IL6 and CRP demonstrated a significant, positive relationship with BMI, WC, hip circumference, fasting glucose, systolic and diastolic blood pressure, triglycerides, insulin and HOMAIR. Adiponectin showed inverse relationship with BMI, WC and fasting glucose. Adiponectin was significantly and negatively correlated with WHR, systolic, diastolic blood pressure and HDLc in overweight group (p<0.05), Triglycerides, cholesterol, TChol/HDL ratio, insulin and HOMAIR p<0.01) in over weight and obese groups. Correlations among the inflammatory markers revealed that Leptin was significantly correlated with adiponectin in normal weight and obese II groups (p<0.01), and with resistin in normal weight, overweight and obese I groups (p<0.01). Adiponectin showed significant negative correlation with CRP (r = -0.324, p<0.01) in obese group II. Resistin was significantly correlated with IL6 and CRP in overweight and obese group II (P<0.01). IL6 was significantly correlated with CRP in overweight, obese I and obese II groups (p<0.01) as compared to the normal weight group. Adiponectin expression was calculated by ∆ CT method. There was a strong correlation between adiponectin m RNA expression (∆ CT) and serum adiponectin levels (p<0.01) in all BMI groups. Adiponectin expression significantly decreased in overweight and obese subjects as compared to the normal weight subjects. Serum resistin was significantly correlated with adiponectin ∆ CT (p<0.05) in overweight group. Serum IL6 also showed significant association with Adiponectin gene expression in BMI group 1 (p<0.05). Adiponectin expression was significantly correlated with cholesterol in normal weight group, overweight group and obese II group (P<0.05). Non significant correlation was observed between adiponectin expression and HDL-c, fasting glucose and insulin levels in all BMI groups. However, Adiponectin expression showed significant correlation with insulin sensitivity in overweight subjects (p<0.05). Relative gene expression showed a significant decrease in adiponectin mRNA expression from 1 fold in control group to 0.4 fold in obese II group. Stepwise multiple regression analysis was performed considering adiponectin gene expression as dependent variable and other significantly correlated parameters as independent variables. BMI, total cholesterol, T chol / HDL ratio, Leptin, CRP, serum insulin and systolic BP were the only variables to enter the regression with p value (p<0.01). The study demonstrated significantly different serum levels of adiponectin, leptin, resistin, IL6 and CRP in overweight, obese I and obese II subjects. There were significant correlations between inflammatory markers and other anthropometric and biochemical parameters. mRNA expression level of adiponectin was significantly influenced by obesity in over weight and obese groups.