Different modulation of dipeptidyl peptidase-4 activity between microvascular and macrovascular human endothelial cells.

Dipeptidyl peptidase 4 (DPP-4) is an enzyme that is produced by endothelial cells in different districts and circulates in plasma. Patients with type 2 diabetes show a reduction in active Glucagon-Like Peptide-1 (GLP-1) that could be due to impairment of secretion or its degradation or both. GLP-1 is rapidly inactivated in vivo, mainly by the DPP-4.

Dipeptidyl peptidase-IV expression and activity in human glomerular endothelial cells.

Glucagon-like peptide-1 (GLP-1), a meal-stimulated gastrointestinal insulinotropic hormone inactivated by dipeptidyl peptidase-IV (DPP-IV), is reduced in type 2 diabetic patients. The present study shows that 2-week exposure of human glomerular endothelial cells to high glucose (22 mM) determines a highly significant increase in DPP-IV activity and mRNA expression, which cannot be entirely accounted for by hyperosmolarity. On the other hand, incubation of purified DPP-IV in a buffer solution added with high glucose does not affect enzyme activity.