Circulating serum fatty acid synthase is elevated in patients with diabetes and carotid artery stenosis and is LDL-associated

Abstract Background and aims Diabetes is an independent risk factor for carotid artery stenosis (CAS). Fatty acid synthase (FAS), an essential de novo lipogenesis enzyme, has increased activity in the setting of diabetes that leads to altered lipid metabolism. Circulating FAS (cFAS) was recently observed in the blood of patients with hyperinsulinemia and cancer. We thought to evaluate the origin of cFAS and its role in diabetes-associated CAS. Methods Patients with diabetes and no diabetes, undergoing carotid endarterectomy (CEA) for CAS, were prospectively enrolled for collection of plaque and fasting serum. FPLC was used to purify lipoprotein fractions, and ELISA was used to quantify cFAS content and activity. Immunoprecipitation (IP) was used to evaluate the affinity of cFAS to LDL-ApoB. Results Patients with CAS had higher cFAS activity ( p p p  = 0.03, r 2  = 0.35), and cFAS content trended with plaque FAS content ( p  = 0.06, r 2  = 0.69). cFAS was predominantly in LDL cholesterol fractions of patients with CAS ( p db/db mice had highest levels of serum cFAS ( p fasL −/− (tissue-specific liver knockdown of FAS) mice had the lowest levels of cFAS ( p Conclusions Serum cFAS is higher in patients with diabetes and CAS, appears to originate from the liver, and is LDL cholesterol associated. We postulate that LDL may be serving as a carrier for cFAS that contributes to atheroprogression in carotid arteries of patients with diabetes.