Cellular retinol-binding protein-1 expression in normal and fibrotic/cirrhotic human liver: different patterns of expression in hepatic stellate cells and (myo)fibroblast subpopulations

Background/Aims Cellular retinol-binding protein-1 (CRBP-1) which is involved in vitamin A metabolism is highly expressed in liver cells, particularly in hepatic stellate cells (HSCs). In this work, the CRBP-1 expression was studied by immunohistochemistry in the different liver cell populations, including HSCs and portal fibroblasts, of normal liver and of fibrotic and cirrhotic liver. Methods Normal liver, fibrotic liver in different stages and cirrhotic liver sections were studied. Immunohistochemistry was performed using antibodies against CRBP-1, α-smooth muscle actin (SMA), CD 68 and CD 34. Results In normal liver, quiescent HSCs expressed CRBP-1, while portal fibroblasts did not. In fibrotic or cirrhotic liver, activated HSCs co-expressed CRBP-1 and α-SMA; a variable proportion of portal and septal (myo)fibroblasts, more important in cirrhosis, neo-expressed both CRBP-1 and α-SMA. Biliary epithelial cells both in normal and pathological situations expressed CRBP-1. Neither Kupffer cells, nor endothelial cells showed CRBP-1 expression. Conclusions Our study demonstrates that CRBP-1 is a good marker to identify HSC in normal human liver. Furthermore, in fibrotic or cirrhotic liver, the different patterns of expression for CRBP-1 and α-SMA allow the distinction of different subsets of fibroblastic cells involved in fibrogenesis and septa formation.