Targeting cluster of differentiation 26 / dipeptidyl peptidase 4 (CD26/DPP4) in organ fibrosis.

Cluster of differentiation 26 (CD26)/dipeptidyl peptidase 4 (DPP4) is an exopeptidase that is expressed as a transmembrane protein in many organs but also present in a circulating soluble form. Beyond its enzymatic and costimulatory activity, CD26/DPP4 is involved in the pathogenesis of chronic fibrotic diseases across many organ types, such as liver cirrhosis, kidney fibrosis and lung fibrosis. Organ fibrosis is associated with a high morbidity and mortality, and there are no causative therapies that can effectively attenuate the progress of the disease. Growing evidence suggests that inhibiting CD26/DPP4 can modulate the profibrotic tissue microenvironment and thus reduce fibrotic changes within affected organs. This review summarizes the role of CD26/DPP4 in fibroproliferative disorders and highlights new opportunities for an antifibrotic treatment by CD26/DPP4 inhibition. As a major advantage, CD26/DPP4 inhibitors have been in safe and routine clinical use in type 2 diabetes for many years and thus qualify for repurposing to repurpose as a promising therapeutic against fibrosis.