title: Higher serum DPP-4 enzyme activity and decreased lymphocyte CD26 expression in type 1 diabetes.
abstract: Dipeptidyl peptidase-4 (DPP-4) is involved in the metabolism of peptide hormones, T-cell activation and proliferation. In type 1 diabetes mellitus (T1DM) β-cell destruction involves a number of dysregulated T-cells. Our aim was to assess the serum DPP-4 activity and the lymphocyte membrane bound CD26 expression in patients with type 1 diabetes and healthy controls. Ninety-eight (T1DM: 48, F/M = 20/28, mean age: 34.4y; control: 50, F/M = 39/11 mean age: 32,4y) individuals were included. Fasting serum DPP-4 enzymatic activity, plasma glucose (FPG), CD26 expression on CD3+, CD4+ and CD8+ lymphocytes, HbA1c and body mass index (BMI) were assessed. ICA and GAD antibodies were assessed in the T1DM group. DPP-4 enzymatic activity was determined by kinetic enzyme assay, ICA and GAD were assessed by ELISA. Determination of the CD26 expression on CD3+, CD4+ and CD8+ lymphocytes was performed by flow-cytometric analysis. We found higher serum DPP-4 activity (Mean: T1DM: 30.069 U/L, control: 22.62 U/L, p < 0.0001) and decreased CD26 lymphocyte expression on all lymphocyte subpopulations in T1DM. Fasting serum DPP-4 activity was independent from the ICA or GAD status of patients with T1DM. Here we first present that the serum DPP-4 activity is increased and the lymphocyte membrane bound CD26 expression is decreased in type 1 diabetes. Decreased lymphocyte membrane bound CD26 expression in T1DM might be a novel part of the T-lymphocyte regulatory dysfunction observed in type 1 diabetes mellitus. These results might provide some basis for the clinical implication of DPP-4 inhibition in patients with T1DM.
authors.affiliation: 2nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary. timcsus@yahoo.com
authors.forename: Tímea
authors.initials: T
authors.lastname: Varga
authors.forename: Anikó
authors.initials: A
authors.lastname: Somogyi
authors.forename: Gábor
authors.initials: G
authors.lastname: Barna
authors.forename: Barna
authors.initials: B
authors.lastname: Wichmann
authors.forename: Géza
authors.initials: G
authors.lastname: Nagy
authors.forename: Károly
authors.initials: K
authors.lastname: Rácz
authors.forename: László
authors.initials: L
authors.lastname: Selmeci
authors.forename: Gábor
authors.initials: G
authors.lastname: Firneisz
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000276:immunology; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000201:enzymology* / Q000276:immunology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000201:enzymology / Q000276:immunology; D018819:Dipeptidyl Peptidase 4 / Q000096:biosynthesis* / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D005215:Fasting / Q000097:blood; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D050417:Insulin-Secreting Cells / Q000201:enzymology / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D001786:Blood Glucose; D018819:Dipeptidyl Peptidase 4; D005968:Glutamate Decarboxylase; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human; C024211:islet cell antibody