A guardian angel: the involvement of dipeptidyl peptidase IV in psychoneuroendocrine function, nutrition and immune defence

Dipeptidyl peptidase IV (DPP IV, also known as CD26; EC 3.4.14.5) is a non- integrin receptor glycoprotein with multiple functions, including cell adhe sion, cellular trafficking through the extracellular matrix and co-stimulat ory potential during T cell activation. By virtue of its exopeptidase activ ity, DPP IV plays a key regulatory role in the metabolism of peptide hormon es. Based on data emerging from different biomedical specialties, it appear s worthwhile to highlight the different facets of DPP IV in nutrition, immu ne responses and peptide hormone metabolism. The presentation of the comple x regulatory circuits in which DPP IV appears to be involved may also serve as a note of caution, in view of attempts to apply selective inhibitors of DPP IV enzymic activity for the treatment of disease, e.g. Type II diabete s.