ESPE Abstracts

Background: Congenital hyperinsulinism (CHI) is the commonest cause of persistent hypoglycaemia and is due to the unregulated secretion of insulin from the pancreatic β-cells. The role of glucagon like peptide-1, gastric inhibitory polypeptide (GLP1/GIP), and dipeptidyl peptidase-4 (DPP4), is currently unknown in patients with CHI.

Objective and Hypotheses: To understand the expression pattern of DPP4 in focal and diffuse disease CHI.

Method: Using formalin-fixed paraffin embedded (FFPE) intra-operative pancreatic sections; immunofluorescence of DPP4 localisation in α-, β-, and δ-cells was carried out in five patients with either focal (F-CHI) or diffuse CHI (D-CHI) with relatively normal tissue sections taken from around the focal lesion as controls. Additionally, using the proliferative marker, Ki67, we attempted to identify the islet-cells that were proliferating.

Results: We identified expression of DPP4 with insulin, glucagon, and somatostatin in their respective cell subtypes. Both F-CHI and D-CHI sections showed an increase in Ki67 expression. In comparison to control tissue, D-CHI showed an increase in β-cell DPP4 expression. However, this was absent in the focal lesions.

Conclusion: In conclusion, this is the first study to show that DPP4 expression profiles are histologically different in F-CHI and D-CHI patients. Therefore, DPP4 might have a role in the pathophysiology of D-CHI and this knowledge might be useful for potential therapeutic applications.