RESUMEN
The GAD65 and IA-2 antibodies (Abs) are biomarkers of the development of type 1 diabetes mellitus (T1DM) in both children and adults. The upper reference limit for the autoantibodies made by the manufacture was established on an adult Chinese population. Here, we established upper reference limits for Northern European adults and children in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. Serum samples from healthy Danish children (0-18 years) and adults (18-70 years) were analysed for GAD65Ab and IA-2Ab using MAGLUMI 800 Chemiluminescence Immunoassay (CLIA). The Kruskal-Wallis test was used for evaluating differences between gender and age groups. No gender or age differences were found for neither GAD65Ab nor IA-2Ab, and a combined upper reference limit for both children and adults could be established. An upper reference limit of 5.1 IU/mL was defined for GAD65Ab and 11.5 U/mL for IA-2Ab. Our results showed a substantial discrepancy with the reference limits established by the manufacturer.
Asunto(s)
Autoanticuerpos/sangre , Glutamato Descarboxilasa/antagonistas & inhibidores , Inmunoensayo/normas , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/antagonistas & inhibidores , Adolescente , Adulto , Anciano , Biomarcadores/sangre , Niño , Preescolar , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 1/etnología , Diabetes Mellitus Tipo 1/inmunología , Europa (Continente) , Femenino , Expresión Génica , Glutamato Descarboxilasa/genética , Glutamato Descarboxilasa/inmunología , Voluntarios Sanos , Humanos , Lactante , Recién Nacido , Luminiscencia , Masculino , Persona de Mediana Edad , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/genética , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/inmunología , Valores de Referencia , Población BlancaRESUMEN
AIM: To gain insight into the presence of islet cell autoimmunity in an ethnic Asian compared with a white European population. METHODS: For this cross-sectional study we recruited people with adult-onset diabetes (age of diagnosis 20-60 years), at tertiary referral centres in Germany (n=1020) and Singapore (n=1088). Glutamic acid decarboxylase and islet antigen 2 antibodies were measured according to Islet Autoantibody Standardization Program protocols. RESULTS: The prevalence of glutamic acid decarboxylase antibody positivity was 13.9% (95% CI 12.1-16.0; P<0.001) in the white European cohort compared with 6.8% (95% CI 5.5-8.4; P<0.001) in the Asian cohort. Glutamic acid decarboxylase antibody positivity was 11.4% (95% CI 7.7-16.6) in Indian, 6.0% (95% CI 3.6-9.9) in Malay and 5.8% (95% CI 4.3-7.7; P<0.001) in Chinese participants. In the white European participants, the prevalence of islet antigen 2 antibody positivity was 7.8% (95% CI 6.4-9.4) compared with 14.8% (95% CI 12.8-17.0; P<0.001) in the Asian cohort as a whole, and among the three ethnicities in the Asian cohort it was 12.4% (95% CI 8.6-17.7) in Indian, 16.8% (95% CI 12.6-22.2) in Malay and 15.7% (95% CI 13.2-18.6) in Chinese participants. Double antibody positivity was seen in 5.7% (95% CI 4.5-7.1) of white European participants compared with 1.6% (95% CI 1.0-2.5; P<0.01) of Asian participants. In the white European cohort, those who were glutamic acid decarboxylase autoantibody-positive had a lower BMI than those who were autoantibody-negative, but this trend was absent in the Asian cohort. CONCLUSIONS: A marked prevalence of islet cell autoimmunity was observed in people with adult-onset diabetes. While glutamic acid decarboxylase antibodies were more frequent in the European cohort, islet antigen 2 antibody positivity was highest in the three ethnic groups in Singapore, suggesting ethnic-specific differences in antibody profiles.
Asunto(s)
Autoanticuerpos/análisis , Enfermedades Autoinmunes/inmunología , Autoinmunidad , Diabetes Mellitus Tipo 2/inmunología , Glutamato Descarboxilasa/antagonistas & inhibidores , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/antagonistas & inhibidores , Adulto , Pueblo Asiatico , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/epidemiología , Enfermedades Autoinmunes/etnología , Biomarcadores/sangre , Estudios de Cohortes , Estudios Transversales , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/etnología , Alemania/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Derivación y Consulta , Singapur/epidemiología , Centros de Atención Terciaria , Población Blanca , Adulto JovenRESUMEN
The Network for Pancreatic Organ donors with Diabetes (nPOD) programme was developed in response to an unmet research need for human pancreatic tissue obtained from individuals with type 1 diabetes mellitus and people at increased risk [i.e. autoantibody (AAb)-positive] for the disease. This necessitated the establishment of a type 1 diabetes-specific AAb screening platform for organ procurement organizations (OPOs). Assay protocols for commercially available enzyme-linked immunosorbent assays (elisas) determining AAb against glutamic acid decarboxylase (GADA), insulinoma-associated protein-2 (IA-2A) and zinc transporter-8 (ZnT8A) were modified to identify AAb-positive donors within strict time requirements associated with organ donation programmes. These rapid elisas were evaluated by the international islet AAb standardization programme (IASP) and used by OPO laboratories as an adjunct to routine serological tests evaluating donors for organ transplantation. The rapid elisas performed well in three IASPs (2011, 2013, 2015) with 98-100% specificity for all three assays, including sensitivities of 64-82% (GADA), 60-64% (IA-2A) and 62-68% (ZnT8A). Since 2009, nPOD has screened 4442 organ donors by rapid elisa; 250 (5·6%) were identified as positive for one AAb and 14 (0.3%) for multiple AAb with 20 of these cases received by nPOD for follow-up studies (14 GADA+, two IA-2A(+) , four multiple AAb-positive). Rapid screening for type 1 diabetes-associated AAb in organ donors is feasible, allowing for identification of non-diabetic, high-risk individuals and procurement of valuable tissues for natural history studies of this disease.
Asunto(s)
Autoanticuerpos/sangre , Selección de Donante/normas , Ensayo de Inmunoadsorción Enzimática/normas , Donantes de Tejidos/provisión & distribución , Adolescente , Adulto , Área Bajo la Curva , Proteínas de Transporte de Catión/antagonistas & inhibidores , Proteínas de Transporte de Catión/genética , Proteínas de Transporte de Catión/inmunología , Niño , Diabetes Mellitus Tipo 1/patología , Diabetes Mellitus Tipo 1/cirugía , Femenino , Glutamato Descarboxilasa/antagonistas & inhibidores , Glutamato Descarboxilasa/genética , Glutamato Descarboxilasa/inmunología , Humanos , Masculino , Persona de Mediana Edad , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/antagonistas & inhibidores , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/genética , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/inmunología , Riesgo , Sensibilidad y Especificidad , Transportador 8 de ZincRESUMEN
BACKGROUND: Islet autoantibody testing provides the basis for assessment of risk of progression to type 1 diabetes. We set out to determine the feasibility and acceptability of dried capillary blood spot-based screening to identify islet autoantibody-positive relatives potentially eligible for inclusion in prevention trials. MATERIALS AND METHODS: Dried blood spot (DBS) and venous samples were collected from 229 relatives participating in the TrialNet Pathway to Prevention Study. Both samples were tested for glutamic acid decarboxylase, islet antigen 2, and zinc transporter 8 autoantibodies, and venous samples were additionally tested for insulin autoantibodies and islet cell antibodies. We defined multiple autoantibody positive as two or more autoantibodies in venous serum and DBS screen positive if one or more autoantibodies were detected. Participant questionnaires compared the sample collection methods. RESULTS: Of 44 relatives who were multiple autoantibody positive in venous samples, 42 (95.5%) were DBS screen positive, and DBS accurately detected 145 of 147 autoantibody-negative relatives (98.6%). Capillary blood sampling was perceived as more painful than venous blood draw, but 60% of participants would prefer initial screening using home fingerstick with clinic visits only required if autoantibodies were found. CONCLUSIONS: Capillary blood sampling could facilitate screening for type 1 diabetes prevention studies.
Asunto(s)
Autoanticuerpos/análisis , Diabetes Mellitus Tipo 1/diagnóstico , Pruebas con Sangre Seca , Islotes Pancreáticos/inmunología , Tamizaje Masivo/métodos , Adolescente , Adulto , Proteínas de Transporte de Catión/antagonistas & inhibidores , Niño , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/inmunología , Europa (Continente) , Salud de la Familia , Estudios de Factibilidad , Femenino , Glutamato Descarboxilasa/antagonistas & inhibidores , Humanos , Anticuerpos Insulínicos/análisis , Masculino , América del Norte , Prioridad del Paciente , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/antagonistas & inhibidores , Sensibilidad y Especificidad , Adulto Joven , Transportador 8 de ZincRESUMEN
BACKGROUND: The ZnT8A is an independent marker for diagnosis of type 1 diabetes mellitus. We investigated the distribution and clinical features of ZnT8A positive latent autoimmune diabetes in adult (LADA) patients to explore the potential diagnostic application. METHODS: A total of 3062 phenotypic T2DM patients were randomly selected from a national multicenter study - the LADA China Study. Radioligand binding assays were applied to detect the presence of ZnT8A, GADA and IA-2A. HbA1c , fasting C-peptide and serum lipid levels were followed up with ZnT8A positive patients. RESULTS: The positive prevalence of ZnT8A, GADA and IA-2A in phenotypic T2DM patients was 1.99% (61/3062), 6.43% (197/3062) and 1.96% (60/3062), respectively. The ZnT8A positivity was lower than that of GADA(x² = 74.8, p < 0.001) but was comparable with that of IA-2A (p > 0.05). The positivity of ZnT8A in IA-2A positive patients was higher than that in GADA positive patients (38.3% vs. 10.7%, x² = 24.8, p < 0.001). On the basis of GADA and IA-2A positivity, the ZnT8A assay enhanced the diagnostic prevalence of LADA from 7.58 to 8.62%. The LADA patients who were positive for ZnT8A had higher systolic blood pressure when compared with GADA positive cases (p = 0.049) and higher total cholesterol levels when compared with antibody-negative T2DM patients (p = 0.035). CONCLUSION: The detection of ZnT8A at the basis of GADA and IA-2A can improve diagnostic sensitivity of Chinese LADA.
Asunto(s)
Autoanticuerpos/análisis , Enfermedades Autoinmunes/diagnóstico , Proteínas de Transporte de Catión/antagonistas & inhibidores , Diabetes Mellitus Tipo 2/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/epidemiología , Enfermedades Autoinmunes/inmunología , Estudios de Casos y Controles , China/epidemiología , Estudios Transversales , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/inmunología , Diagnóstico Diferencial , Estudios de Seguimiento , Glutamato Descarboxilasa/antagonistas & inhibidores , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Ensayo de Unión Radioligante , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/antagonistas & inhibidores , Sensibilidad y Especificidad , Transportador 8 de ZincRESUMEN
Phogrin is a transmembrane protein expressed in cells with stimulus-coupled peptide hormone secretion, including pancreatic beta cells, in which it is localized to the membrane of insulin-containing dense-core vesicles. By sequence, phogrin is a member of the family of receptor-like protein-tyrosine phosphatases, but it contains substitutions in conserved catalytic sequences, and no significant enzymatic activity for phogrin has ever been reported. We report here that phogrin is able to dephosphorylate specific inositol phospholipids, including phosphatidylinositol (PI) 3-phosphate and PI 4,5-diphosphate but not PI 3,4,5-trisphosphate. The phosphatidylinositol phosphatase (PIPase) activity of phogrin was measurable but low when evaluated by the ability of a catalytic domain fusion protein to hydrolyze soluble short-chain phosphatidylinositol phospholipids. Unlike most PIPases, which are cytoplasmic proteins that associate with membranes, mature phogrin is a transmembrane protein. When the transmembrane form of phogrin was overexpressed in mammalian cells, it reduced plasma membrane phosphatidylinositol 4,5-disphosphate levels in a dose-dependent manner. When purified and assayed in vitro, the transmembrane form had a specific activity of 142 mol/min/mol, 75-fold more active than the catalytic domain fusion protein and comparable with the specific activities of the other PIPases. The PIPase activity of phogrin depended on the catalytic site cysteine and correlated with effects on glucose-stimulated insulin secretion. We propose that phogrin functions as a phosphatidylinositol phosphatase that contributes to maintaining subcellular differences in levels of PIP that are important for regulating stimulus-coupled exocytosis of insulin.