Serum amyloid A is found on ApoB-containing lipoproteins in obese humans with diabetes

Objective: In murine models of obesity/diabetes, there is an increase in plasma serum amyloid A (SAA) levels along with redistribution of SAA from high-density lipoprotein (HDL) to apolipoprotein B (apoB)-containing lipoprotein particles, namely, low-density lipoprotein and very low-density lipoprotein. The goal of this study was to determine if obesity is associated with similar SAA lipoprotein redistribution in humans. Design and Methods: Three groups of obese individuals were recruited from a weight loss clinic: healthy obese (n = 14), metabolic syndrome (MetS) obese (n = 8), and obese with type 2 diabetes (n = 6). Plasma was separated into lipoprotein fractions by fast protein liquid chromatography, and SAA was measured in lipid fractions using enzyme-linked immunosorbent assay and Western blotting. Results: Only the obese diabetic group had SAA detectable in apoB-containing lipoproteins, and SAA reverted back to HDL with active weight loss. Conclusions: In human subjects, SAA is found in apoB-containing lipoprotein particles only in obese subjects with type 2 diabetes, but not in healthy obese or obese subjects with MetS.