Lipocalin 2 in the pathogenesis of fatty liver disease and nonalcoholic steatohepatitis

The lipocalins were originally classified as a widespread group of transport proteins for small hydrophobic molecules. Although they only share a limited sequence homology their 3D fold is conserved. This group of proteins has been implicated in a multitude of biological processes that most often become visible during disease formation. Lipocalin 2 (LCN2) serves as a siderocalin and protects against bacterial infections. In the liver, LCN2 expression is upregulated during inflammation and in response to cellular stress evolving protective effects during acute and chronic injury. LCN2 was shown to act as an adipokine in the pathogenesis of nonalcoholic fatty liver disease and in control of brown adipose tissue activation. In a nutritional model of nonalcoholic steatohepatitis, LCN2 was identified as a key factor that controls the expression of the perlipin 5 regulating cellular lipid droplet formation. We here summarize experimental and clinical findings linking LCN2 to fatty liver disease.