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Abstract

Objective: Black South African (SA) women are more insulin resistant and have increased gluteal subcutaneous adipose tissue (SAT) hypertrophy than white SA women. We tested the hypothesis that adipose tissue hypoxia and extracellular matrix (ECM) gene expression in gluteal and abdominal SAT is higher in black than white women, and associates with reduced insulin sensitivity (SI) in black women. Methods: SI (frequently sampled intravenous glucose tolerance test), gluteal and abdominal SAT mRNA levels of hypoxia- and ECMrelated genes were measured in normal-weight and obese premenopausal black (n=30) and white (n=26) SA women at baseline, and in black women, at 5-year follow-up (n=10). Results: Compared to obese white women, obese black women had higher expression of hypoxia inducible factor 1 (HIF-1�±), collagen type V�±1 (Col5a1) and collagen VI�±1 Col6a1 and reduced vascular endothelial growth factor-�± (VEGF�±) expression in gluteal (p<0.05) but not abdominal SAT depots. Independent of body fatness, gluteal expression of HIF-1�± (r=-0.55; p=0.01), Col5a1 (r=-0.41; p=0.05) and Col6a1 (r=-0.47; p=0.03) correlated with reduced SI in black women only. Over a 5-year follow-up, changes in gluteal HIF-1�± (r=0.58; p=0.01), Col5a1 (r=0.82; p=0.02), and Col6a1 (r=0.88; p<0.00) expression correlated positively with the change in fasting insulin concentrations in black women. Conclusion: Compared to their white counterparts, black women expressed higher levels of genes associated with hypoxia and collagen deposition, and that the associations between these genes and SI differed by ethnicity. We thus propose that insulin resistance in black women may be related to higher ECM and hypoxia gene expression.

Biography

Email: liske.kotze@gmail.com