Visfatin Gene Expression In Adipose Tissue In Obesity And Type 2 Diabetes Mellitus And Its Relationship To Insulin Sensitivity

Objectives:Visceral and subcutaneous adipose tissue display important metabolic differences that underlie the association of visceral obesity with obesity-related cardiovascular and metabolic alterations.Visfatin was recently identified as an adipokine and predominantly secreted from visceral adipose tissue with insulin-mimetic effect and is a candidate hormone to help explain the association among adipose tissue expansion, insulin resistance,and type 2 diabetes mellitus.In this study we assess expression of visfatin in subcutaneous and visceral adipose tissue and investigate whether plasma visfatin level is altered in patients with obesity and type 2 diabetes mellitus,and moreover to explore its relationship to insulin sensitivity.Methods:In this study,we examined whether visfatin mRNA expression (using real time RT-PCR)in subcutaneous and visceral fat and plasma visfatin concentrations(using enzyme immunosorbent assay)correlates with anthropometric and metabolic parameters in obesity subjects and type 2 diabetes mellitus.Results:(1)Visfatin mRNA was similarly expressed in the SAT of control,obese subjects and type 2 diabetes mellitus.(2)Significantly higher visfatin mRNA was found in VAT of obese subjects and control, and lower visfatin mRNA was found in VAT of type 2 diabetes mellitus, compared with SAT of normol-weight control.Visfatin mRNA was similarly expressed in the VAT of control and obese subjects.(3)Plasma visfatin level did not differ between the groups.(4)SAT VF mRNA associated positively with VAT VF mRNA(r=0.488,P=0.0075)and negatively with FPG and HbA1c(r=-0.582,-0.428,P＜0.001,P=0.0206), whereas VAT VF mRNA associated positively with HDL-C and Apo-A1(r=0.422,0.535,P=0.0229,P=0.0030)and negatively with FPG, HbA1c and plasma visfatin concentration).(r=-0.634,-0.521,-0.388,P＜0.001,P=0.006,P=0.0374).In a multiple linear regression analysis, only FPG was independently associated with SAT and VAT VF(P＜0.001). Plasma visfatin level did not differ between the groups.Visfatin plasma concentration correlates positively with FPG(r=0.57,P=0.0013)and negatively with CHOL(r=-0.45,P=0.0145).In a multiple linear regression analysis,CHOL was independently associated with plasma visfatin level (P=0.021).(5)SAT and VAT visfatin mRNA and visfatin plasma concentration did not correlate with HOMA-IR.Conclusions:(1)The visfatin gene expression is predominantly secreted from visceral adipose tissue and down-regulated by hyperglycemia.(2) There was no significant difference in the visfatin concentration between the T2DM and obesity groups as well as obesity group and healthy controls.Our findings show that,the visfatin gene is linked with glucose and lipid metabolism but not related to insulin resistance.The level of plasma visfatin may not be a diagnoses parameter of obesity and T2DM.