Publication: Immunology

Obesity is associated with adipose tissue inflammation that is involved in the development of insulin resistance and type 2 diabetes. Osteopontin (OPN) and IL-18 are known to have potent inflammatory functions and both participate in a wide range of biological processes linked to immunological disorders. Since an interaction between OPN and IL-18 has been suggested in inflammatory diseases, we investigated whether: 1 Their levels were elevated in obese individuals; 2 Associated with blood glucose and BMI. PBMCs and plasma samples were isolated from 77 individuals including lean as well as overweight and obese, with or without diabetes. Plasma concentrations of OPN and IL-18 were measured by ELISA. OPN and IL-18 mRNA expression was quantified in PBMCs by RT-PCR. As compared with lean controls, obese individuals showed significantly higher plasma concentrations of OPN (lean 2171 ± 203 pg/ml versus obese 2865 ± 101 pg/ml; P < 0.002) and IL-18 (lean 308 ± 45 versus obese 629 ± 96 pg/ml; P < 0.01). OPN showed a significant positive correlation with BMI (P < 0.0001) and blood glucose level (P < 0.03). Similarly, IL-18 positively correlated with BMI (P < 0.05) and blood glucose level (P < 0.05). Interestingly, there was a strong association between OPN and IL-18 in obese individuals. To our knowledge this is the first demonstration showing that plasma OPN and IL-18 are simultaneously increased in overweight/ obese individuals which may trigger obesity-associated/insulinresistance development. Further studies are being carried out to dissect the pathways that involve OPN and IL-18 in obesity.

View Article