Preadipocyte Factor-1 Is Associated with Metabolic Profile in Severe Obesity

Abstract

Dysfunctional adipose tissue has been proposed as a key pathological process linking obesity and metabolic disease. Preadipocyte factor-1 (Pref-1) has been shown to inhibit differentiation in adipocyte precursor cells and could thereby play a role in determining adipocyte size, adipose tissue functioning, and metabolic profile in obese individuals. We hypothesized that adipose tissue from metabolically healthy obese (MHO) and matched metabolically unhealthy obese individuals would demonstrate distinct differences in relation to Pref-1 expression, adipocyte size, and inflammatory markers. This was a cross-sectional study, investigating obese patients undergoing bariatric surgery at a tertiary referral centre. Patients included 12 MHO and 17 age- and body mass index-matched metabolically unhealthy obese individuals. Pref-1, monocyte chemotactic protein-1, TNF-α, granulocyte colony-stimulating factor, IL-6, and adiponectin levels, macrophage numbers, and adipocyte size were measured in omental and subcutaneous adipose tissue. The MHO group had a lower level of Pref-1 (per 1000 adipocytes) in both subcutaneous [160 (136-177) versus 194 (153-355); P < 0.05] and omental adipose tissue [102 (32-175) versus 194 (100-350); P < 0.005]. This was associated with lower numbers of macrophages, lower levels of TNF-α, monocyte chemotactic protein-1, and granulocyte colony-stimulating factor, and higher levels of adiponectin. Omental Pref-1 showed strong correlations with adipocyte size (r = 0.67, P < 0.0005) and metabolic and adipokine parameters, including percent fatty liver (r = 0.62, P < 0.005), fasting glucose (r = 0.68, P < 0.0005), triglyceride (r = 0.60, P < 0.005), high-density lipoprotein cholesterol (r = -0.46, P < 0.05), and adiponectin (r = -0.71, P < 0.05). Adipose tissue in MHO individuals had lower levels of Pref-1, a known inhibitor of preadipocyte differentiation, and a more favorable inflammatory profile. These factors may be key to protecting this subgroup of obese individuals from the adverse metabolic profile associated with excess adiposity.