Abstract 477: Adipocyte Twist-1 Deficiency Exacerbates Weight Gain, Glucose Intolerance and Adipose Tissue Inflammation in Females

Abstract

Twist1 is a transcription factor abundantly expressed by adipocytes, immune and vascular cells in adipose tissue (AT) in humans and rodents. Low twist1 expression in human AT is correlated with insulin resistance and obesity. However the role of twist-1 in different cell types component of AT is not clear. The objective of this study was to determine the role of adipocyte (Adp) twist-1 in obesity and insulin resistance. Adp-specific twist1 knock out mice ( AdiponectinCreTwistflox ) (n=6) on the C57Bl6/J background were maintained on 60%kcal fat diet for 12 weeks. Compared to littermate controls (n=6), the female mutant mice, but not the males, showed a 3- and 1.5- fold increase in visceral and subcutaneous adiposity, respectively. Similarly, only the mutant females had significantly impaired glucose tolerance (P<0.05) compared to the littermate controls. Peri-gonadal AT in mutant females showed increased CD11b+F4/80+ and CD3+CD8+ numbers compared to controls, however no differences were found between the male mice. The female mutant mice had more hypertrophied Adp and displayed a 2-4-fold increase in gene expression of IFN γ, TNF α, CD3e and Jak2 compared to controls. Also, expression of the lipogenic enzymes Acaca and Acls4 were significantly reduced by 2.2-fold in the mutant females. Interestingly expression of Nampt (visfatin) gene was significantly increased in mutant females compared to both controls and mutant males. Importantly, twist1 expression in visceral Adp of obese human females (n=15) and males (n=8) at the time of bariatric surgery was significantly higher in females (p<0.01). Also, in a longitudinal cohort at ~1.2 years following surgical weight loss, twist1 expression was significantly increased in visceral AT of males (n=3) (p<0.05) but not in females (n=6) despite a similar reduction in body weight. Collectively the rodent data suggest that twist1 deficiency in Adp increases AT inflammation and exacerbates adiposity and glucose intolerance only in females and identifies visfatin as a metabolically relevant gene potentially regulated by twist1 in females. Also, obese human females may be protected by constitutively higher expression of twist1 in visceral Adp and surgical weight loss leads to increased twist1 expression in males.