MicroRNAs and benign biliary tract diseases.

Cholangiocytes, the epithelial cells lining the biliary tree, represent only a small portion of the total liver cell population (3-5%), but they are responsible for the secretion of up to 40% of total daily bile volume. In addition, cholangiocytes are the target of a diverse group of liver diseases affecting the biliary tract, the cholangiopathies; for most of these conditions, the pathological mechanisms are unclear. MicroRNAs (miRNAs) are small, noncoding RNAs that posttranscriptionally regulate gene expression. Thus, it is not surprising that altered miRNA profiles underlie the dysregulation of several proteins involved in the pathobiology of the cholangiopathies, as well as showing promise as diagnostic and prognostic tools. Here the authors review recent work relevant to the role of miRNAs in the etiopathogenesis of several of the cholangiopathies (i.e., fibroinflammatory cholangiopathies and polycystic liver diseases), discuss their value as prognostic and diagnostic tools, and provide suggestions for further research. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.