Adipose tissue 11HSD1 gene expression, cell function and ectopic fat in obese African Americans versus Hispanics

Objective This study examined the contribution of subcutaneous adipose tissue (SAT) 11HSD1 to obese African Americans' (AA) elevated metabolic risk, despite a protective obesity phenotype of reduced visceral adipose tissue (VAT) and hepatic fat fraction (HFF) relative to obese Hispanics with similar metabolic risk. Design and Methods Obese AA and Hispanic adults (N = 36(16AA); BMI 35.2 +/- 0.6 kg/m2, 18-25y) participated, with VAT, SAT, and HFF measured by MRI, SAT gene expression measured by HT-12 microarray and insulin sensitivity (SI), disposition index (DI) by IVGTT. Multiple linear regression examined relationships/interactions of ethnicity and 11HSD1 expression on outcomes (covariates: age, sex, total fat mass), with standardized (st) reported. Results SAT 11HSD1 expression significantly associated with insulin parameters and this varied by ethnicity (Pinteraction<0.1). In AA, 11HSD1 negatively associated with SI (st = -0.58, P = 0.03), DI (st = -0.62, P = 0.03) and positively associated with fasting insulin (st = 0.54, P = 0.04), with no significant relationship in Hispanics. SAT 11HSD1 associated with HFF in the combined sample (st = 0.42, P = 0.008), with no difference between ethnicites (Pinteraction>0.1). After controlling for HFF, 11HSD1 associations with metabolic risk in AA became nonsignificant. Conclusions These results suggested that in AA and not Hispanics, SAT 11HSD1 is associated with SI and DI, and may be mediated by HFF.