scholarly journals Characterization of zinc transporter 8 (ZnT8) antibodies in autoimmune diabetic patients from Argentinian population using monomeric, homodimeric, and heterodimeric ZnT8 antigen variants

2016 ◽  
Vol 174 (2) ◽  
pp. 157-165 ◽  
Author(s):  
Natalia I Faccinetti ◽  
Luciano L Guerra ◽  
Alberto Penas Steinhardt ◽  
Ruben F Iacono ◽  
Gustavo D Frechtel ◽  
...  
Keyword(s):  
Radioligand Binding ◽  
Zinc Transporter ◽  
Actual State ◽  
Diabetic Patients ◽  
Obese Adult ◽  
Adult Onset ◽  
Β Cell ◽  
Zinc Transporter 8 ◽  
Type 1 Diabetic Patients

ObjectiveIn order to gain further knowledge of the structure of zinc transporter 8 (ZnT8) epitopes, we studied the role of the amino acid at position 325 in the antigen and its dimeric conformation for autoantibodies to ZnT8 (ZnT8A) recognition.MethodsFor this purpose, several ZnT8 C-terminal domain variants were designed: monomer carrying Arg325 or Trp325, homo-dimers ZnT8-Arg–Arg325 and ZnT8-Trp–Trp325, and hetero-dimer ZnT8-Arg–Trp325. Two groups of Argentinian diabetic patients were subjected to analysis using [35S]-ZnT8 variants by radioligand binding assay (RBA): i) 100 new-onset, insulin-dependent, type 1 diabetic patients and ii) 282 slowly progressing to insulin requirement, non-obese adult-onset diabetic patients. In addition, 50 type 1 diabetic patients and 100 normal control sera provided by the American Diabetes Association (ADA) were evaluated in order to calculate the sensitivity and specificity of ZnT8A assays for each antigenic variant. Other routine β-cell autoantibodies were also tested by RBA.ResultsOf the 100 Argentinian type 1 diabetic patients, 65 were ZnT8A+. Out of them, 8 patients recognized all recombinant forms of ZnT8 and most patients (56) reacted against the heterodimer. Additionally, out of 282 non-obese adult-onset diabetic patients 46 were ZnT8A+, whereas 29 patients recognized only dimers. Besides, exclusive reactivity against ZnT8A was found in 9.0% for type 1 diabetes mellitus and 10.3% for non-obese adult-onset diabetic patients.ConclusionsSignificantly higher signal values in RBA were obtained with the heterodimeric variant. An increased detection of humoral autoimmunity was found in both groups when ZnT8A was employed in combination with the other β-cell autoantibodies. The inclusion of homodimeric immunoreactive peptides revealed the existence of quaternary structure-defined epitopes probably resembling the actual state of the autoantigenin vivo. Finally, the differential profiles of ZnT8A exhibited by type 1 and non-obese adult-onset diabetic patients suggest the different nature of autoimmune processes underlying both pathologies.

scholarly journals Differences in the humoral autoreactivity to zinc transporter 8 between childhood- and adult-onset type 1 diabetes in Japanese patients

2011 ◽  
Vol 138 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Eiji Kawasaki ◽  
Kan Nakamura ◽  
Genpei Kuriya ◽  
Tsuyoshi Satoh ◽  
Masakazu Kobayashi ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Japanese Patients ◽  
Zinc Transporter ◽  
Adult Onset ◽  
Onset Type ◽  
Zinc Transporter 8

Type 1 Diabetic Serum Interferes with Pancreatic β-cell Ca2+ -Handling

2007 ◽  
Vol 27 (6) ◽  
pp. 321-326 ◽  
Author(s):  
N. Dekki ◽  
R. Nilsson ◽  
S. Norgren ◽  
S. M. Rössner ◽  
I. Appelskog ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Ethnic Background ◽  
Diabetic Patients ◽  
Pancreatic Β Cell ◽  
Newly Diagnosed ◽  
Β Cells ◽  
Β Cell ◽  
First Degree Relatives ◽  
Type 1 Diabetic Patients

The aim of this study was to clarify the frequency of patients with type 1 diabetes that have serum that increases pancreatic β-cell cytoplasmic free Ca2+ concentration, [Ca2+]i, and if such an effect is also present in serum from first-degree relatives. We also studied a possible link between the serum effect and ethnic background as well as presence of autoantibodies. Sera obtained from three different countries were investigated as follows: 82 Swedish Caucasians with newly diagnosed type 1 diabetes, 56 Americans with different duration of type 1 diabetes, 117 American first-degree relatives of type 1 diabetic patients with a mixed ethnic background and 31 Caucasian Finnish children with newly diagnosed type 1 diabetes. Changes in [Ca2+]i, upon depolarization, were measured in β-cells incubated overnight with sera from type 1 diabetic patients, first-degree relatives or healthy controls. Our data show that there is a group constituting approximately 30% of type 1 diabetic patients of different gender, age, ethnic background and duration of the disease, as well as first-degree relatives of type 1 diabetic patients, that have sera that interfere with pancreatic β-cell Ca2+-handling. This effect on β-cell [Ca2+]i could not be correlated to the presence of autoantibodies. In a defined subgroup of patients with type 1 diabetes and first-degree relatives a defect Ca2+-handling may aggravate development of β-cell destruction.

scholarly journals Effect of Glucagon-Like Peptide-1 on α- and β-Cell Function in C-Peptide-Negative Type 1 Diabetic Patients

2010 ◽  
Vol 24 (4) ◽  
pp. 875-875
Author(s):  
Urd Kielgast ◽  
Meena Asmar ◽  
Sten Madsbad ◽  
Jens J. Holst
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Glucagon Secretion ◽  
Diabetic Patients ◽  
Β Cell ◽  
C Peptide ◽  
Endogenous Insulin Secretion ◽  
Endogenous Insulin ◽  
Type 1 Diabetic Patients

Abstract Context: The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect. Objective: Our objective was to characterize the α- and β-cell responses to GLP-1 in type 1 diabetic patients without residual β-cell function. Methods: Nine type 1 diabetic patients, classified as C-peptide negative by a glucagon test, were clamped at plasma glucose of 20 mmol/liter for 90 min with arginine infusion at time 45 min and concomitant infusion of GLP-1 (1.2 pmol/kg · min) or saline. Results: Infusion with GLP-1 increased C-peptide concentration just above the detection limit of 33 pmol/liter in one patient, but C-peptide remained immeasurable in all other patients. In the eight remaining patients, total area under the curve of glucagon was significantly decreased with GLP-1 compared with saline: 485 ± 72 vs. 760 ± 97 pmol/liter · min (P < 0.001). In addition, GLP-1 decreased the arginine-stimulated glucagon release (incremental AUC of 103 ± 21 and 137 ± 16 pmol/liter · min, with GLP-1 and saline, respectively, P < 0.05). Conclusions: In type 1 diabetic patients without endogenous insulin secretion, GLP-1 decreases the glucagon secretion as well as the arginine-induced glucagon response during hyperglycemia. GLP-1 induced endogenous insulin secretion in one of nine type 1 diabetic patients previously classified as being without endogenous insulin secretion.

scholarly journals Effect of Glucagon-Like Peptide-1 on α- and β-Cell Function in C-Peptide-Negative Type 1 Diabetic Patients

2010 ◽  
Vol 95 (5) ◽  
pp. 2492-2496 ◽  
Author(s):  
Urd Kielgast ◽  
Meena Asmar ◽  
Sten Madsbad ◽  
Jens J. Holst
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Glucagon Secretion ◽  
Diabetic Patients ◽  
Β Cell ◽  
C Peptide ◽  
Endogenous Insulin Secretion ◽  
Endogenous Insulin ◽  
Type 1 Diabetic Patients

Abstract Context: The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect. Objective: To characterize the α- and β-cell responses to GLP-1 in type 1 diabetic patients without residual β-cell function. Methods: Nine type 1 diabetic patients, classified as C-peptide negative by a glucagon test, were clamped at plasma glucose of 20 mmol/liter for 90 min with arginine infusion at time 45 min and concomitant infusion of GLP-1 (1.2 pmol/kg · min) or saline. Results: Infusion with GLP-1 increased C-peptide concentration just above the detection limit of 33 pmol/liter in one patient, but C-peptide remained immeasurable in all other patients. In the eight remaining patients, total area under the curve of glucagon was significantly decreased with GLP-1 compared with saline: 485 ± 72 vs. 760 ± 97 pmol/liter · min (P < 0.001). In addition, GLP-1 decreased the arginine-stimulated glucagon release (incremental AUC of 103 ± 21 and 137 ± 16 pmol/liter · min, with GLP-1 and saline, respectively, P < 0.05). Conclusions: In type 1 diabetic patients without endogenous insulin secretion, GLP-1 decreases the glucagon secretion as well as the arginine-induced glucagon response during hyperglycemia. GLP-1 induced endogenous insulin secretion in one of nine type 1 diabetic patients previously classified as being without endogenous insulin secretion.

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