The Biology of the Cholangiocytes

Choi, Ho Soon

Abstract

The biliary system is comprised of intrahepatic bile ducts, extrahepatic bile ducts, and the gallbladder. Bile is transported in the biliary ductal system. The length of the biliary ductal system in humans is about 2 kilometers. A layer of epithelial cells lines this extensive network. In general, cholangiocytes is defined as the epithelial cells that line the intrahepatic bile ducts. The extrahepatic ductal epithelial cells and gallbladder epithelial cells share many features of cholangiocytes. The primary cell target of biliary disorders is the biliary epithelium. Cholangiocytes have many functions, not limited to bile production. Cholangiocytes are involved in transport processes that regulate the volume and composition of bile. Cholangiocytes undergo proliferation and cell death under a variety of conditions. Cholangiocytes have functional and morphological heterogenecity - not all cholangiocytes are the same functionally and morphologically. The immunobiology of the cholangiocyte is important, particulary to the understanding of biliary disease. Secretion of different pro-inflammatory mediators, cytokines, and chemokines indicates a major role of cholangiocytes in the inflammatory reaction. Furthermore, paracrine secretion of growth factors and peptides mediates an extensive cross-talk with other liver cells, including hepatocytes, stellate, and endothelial and inflammatory cells.