Fetuin a (AHSG) in Metabolic and Inflammatory Diseases: A Foe or A Friend

Fetuin A/AHSG was first isolated by Pedersen in 1944 from the fetal bovine serum. In adult humans, fetuin A is mainly secreted by the liver and the adipose tissue and it acts as an inhibitor of ectopic calcification. Fetuin A is also related to critical aspects of cardiometabolic health in humans such as insulin sensitivity, glucose tolerance, non-alcoholic fatty liver disease, atherosclerosis, and cardiovascular disease. The emerging evidence supports fetuin A as a pleiotropic glycoprotein with both inflammatory and anti-inflammatory attributes. In this paper, we briefly review the available literature that supports the diverse role of fetuin A as a positive acute phase reactant (its pathologic role) as well as a negative acute phase protein (its protective role). This functional paradox of fetuin A seems to be inherent in its unique ability to interact with multiple receptors that can regulate key activities related to both human health and disease.