BB rat Gimap gene expression in sorted lymphoid T and B cells

Aims: The Gimap gene family has been shown to be integral to T cell survival and development. A frameshift mutation in Gimap5, one of seven members of the Gimap family, results in lymphopenia and is a prerequisite for spontaneous type 1 diabetes (T1D) in the BioBreeding (BB) rat. While not contributing to lymphopenia, the Gimap family members proximal to Gimap5, encompassed within the Iddm39 quantitative trait locus (QTL), have been implicated in T1D. We hypothesized that expression of the Gimap family members within the Iddm39 QTL, during thymocyte development as well as in peripheral T and B cells contribute to T1D. Main methods: Cell sorted subpopulations were analyzed by quantitative real time (qRT) PCR. Key findings: Gimap4 expression was reduced in DR.(lyp/lyp) rat double negative, double positive and CD8 single positive (SP) thymocytes while expression of Gimap8, Gimap6, and Gimap7 was reduced only in CD8 SP thymocytes. Interestingly, expression of the entire Gimap gene family was reduced in DR.(lyp/lyp) rat peripheral T cells compared to non-lymphopenic, non-diabetic DR.(+/+) rats. With the exception of Gimap6. the Gimap family genes were not expressed in B cells from spleen and mesenteric lymph node (MLN). Expression of Gimap9 was only detected in hematopoietic cells of non B cell lineage such as macrophage, dendritic or NK cells. Significance: These results suggest that lack of the Gimap5 protein in the DR.(lyp/lyp) congenic rat was associated with impaired expression of the entire family of Gimap genes and may regulate T cell homeostasis in the peripheral lymphoid organs. (C) 2011 Elsevier Inc. All rights reserved

A New Luminescence Assay for Autoantibodies to Mammalian Cell–Prepared Insulinoma-Associated Protein 2

OBJECTIVE—Insulinoma-associated protein 2 (IA-2) is a major autoantigen in type 1 diabetes, and IA-2 autoantibodies are routinely detected by a liquid-phase radioimmunoprecipitation assay. The present experiments were initiated to develop a new assay that does not require the use of radioisotopes or autoantigens prepared in bacteria or by in vitro transcription/translation

Serological evaluation of possible exposure to Ljungan virus and related parechovirus in autoimmune (type 1) diabetes in children.

Exposure to Ljungan virus (LV) is implicated in the risk of autoimmune (type 1) diabetes but possible contribution by other parechoviruses is not ruled out. The aim was to compare children diagnosed with type 1 diabetes in 2005-2011 (n = 69) with healthy controls (n = 294), all from the Jämtland County in Sweden, using an exploratory suspension multiplex immunoassay for IgM and IgG against 26 peptides of LV, human parechoviruses (HPeV), Aichi virus and poliovirus in relation to a radiobinding assay (RBA) for antibodies against LV and InfluenzaA/H1N1pdm09. Islet autoantibodies and HLA-DQ genotypes were also determined. 1) All five LV-peptide antibodies correlated to each other (P < 0.001) in the suspension multiplex IgM- and IgG-antibody assay; 2) The LV-VP1_31-60-IgG correlated with insulin autoantibodies alone (P = 0.007) and in combination with HLA-DQ8 overall (P = 0.022) as well as with HLA-DQ 8/8 and 8/X subjects (P = 0.013); 3) RBA detected LV antibodies correlated with young age at diagnosis (P < 0.001) and with insulin autoantibodies (P < 0.001) especially in young HLA-DQ8 subjects (P = 0.004); 4) LV-peptide-VP1_31-60-IgG correlated to RBA LV antibodies (P = 0.009); 5) HPeV3-peptide-IgM and -IgG showed inter-peptide correlations (P < 0.001) but only HPeV3-VP1_1-30-IgG (P < 0.001) and VP1_95-124-IgG (P = 0.009) were related to RBA LV antibodies without relation to insulin autoantibody positivity (P = 0.072 and P = 0.486, respectively). Both exploratory suspension multiplex IgG to LV-peptide VP1_31-60 and RBA detected LV antibodies correlated with insulin autoantibodies and HLA-DQ8 suggesting possible role in type 1 diabetes. It remains to be determined if cross-reactivity or concomitant exposure to LV and HPeV3 contributes to the seroprevalence. J. Med. Virol. © 2015 Wiley Periodicals, Inc

Comparison of Radioimmunoprecipitation With Luciferase Immunoprecipitation for Autoantibodies to GAD65 and IA-2β

OBJECTIVE - To compare the sensitivity and specificity of luciferase immunoprecipitation (LIPS) with radioimmunoprecipitation (RIP) for the measurement of autoantibodies to the type 1 diabetes autoantigens glutamic acid decarboxylase 65 (GAD65) and insulinoma-associated protein (IA)-2 beta. RESEARCH DESIGN AND METHODS - Sera from 49 type 1 diabetic patients and 100 nondiabetic control subjects from Diabetes Antibody Standardization Program 2007 were used to screen for autoantibodies to GAD65. An additional 200 type 1 diabetic patients and 200 nondiabetic control subjects were used to validate the GAD65 results and screen for autoantibodies to IA-2 beta. RESULTS - LIPS showed equal sensitivity and specificity to RIP for detecting autoantibodies to GAD65 and IA-2 beta. Receiver-operating characteristic analysis revealed that the detection of autoantibodies to GAD65 and IA-2 beta by LIPS and RIP were not statistically different. CONCLUSIONS - The LIPS assay does not require the use of radioisotopes or in vitro transcription/translation and is a practical alternative at the clinical level for the RIP assay

Islet autoantibodies and residual beta cell function in type 1 diabetes children followed for 3-6 years

Aims: To test if islet autoantibodies at diagnosis of type 1 diabetes (T1DM) and after 3-6 years with T1D predict residual beta-cell function (RBF) after 3-6 years with T1D. Methods: T1D children (n = 260, median age at diagnosis 9.4, range 0.9-14.7 years) were tested for GAD65, IA-2, ZnT8R, ZnT8W and ZnT8Q autoantibodies (A) at diagnosis, and 3-6 years after diagnosis when also fasting and stimulated RBF were determined. Results: For every 1-year increase in age at diagnosis of TID, the odds of detectable C-peptide increased 1.21 (1.09, 1.34) times for fasting C-peptide and 1.28 (1.15, 1.42) times for stimulated C-peptide. Based on a linear model for subjects with no change in IA-2A levels, the odds of detectable C-peptide were 35% higher than for subjects whose IA-2A levels decreased by half (OR = 1.35 (1.09, 1.67), p = 0.006); similarly for ZnT8WA (OR = 1.39 (1.09, 1.77), p = 0.008) and ZnT8QA (OR = 1.55 (1.06, 2.26) p = 0.024). Such relationship was not detected for GADA or ZnT8RA. All OR adjusted for confounders. Conclusions: Age at diagnosis with T1D was the major predictor of detectable C-peptide 3-6 years post-diagnosis. Decreases in IA-2A, and possibly ZnT8A, levels between diagnosis and post-diagnosis were associated with a reduction in RBF post-diagnosis. (C) 2012 Elsevier Ireland Ltd. All rights reserved

Sequence Variation and Expression of the Gimap Gene Family in the BB Rat

Positional cloning of lymphopenia (lyp) in the BB rat revealed a frameshift mutation in Gimap5, a member of at least seven related GTPase Immune Associated Protein genes located on rat chromosome 4q24. Our aim was to clone and sequence the cDNA of the BB diabetes prone (DP) and diabetes resistant (DR) alleles of all seven Gimap genes in the congenic DR.lyp rat line with 2 Mb of BB DP DNA introgressed onto the DR genetic background. All (100%) DR.lyp/lyp rats are lymphopenic and develop type 1 diabetes (T1D) by 84 days of age while DR.+/+ rats remain T1D and lyp resistant. Among the seven Gimap genes, the Gimap5 frameshift mutation, a mutant allele that produces no protein, had the greatest impact on lymphopenia in the DR.lyp/lyp rat. Gimap4 and Gimap1 each had one amino acid substitution of unlikely significance for lymphopenia. Quantitative RT-PCR analysis showed a reduction in expression of all seven Gimap genes in DR.lyp/lyp spleen and mesenteric lymph nodes when compared to DR.+/+. Only four; Gimap1, Gimap4, Gimap5, and Gimap9 were reduced in thymus. Our data substantiates the Gimap5 frameshift mutation as the primary defect with only limited contributions to lymphopenia from the remaining Gimap genes

Transcriptional networks in at-risk individuals identify signatures of type 1 diabetes progression.

Type 1 diabetes (T1D) is a disease of insulin deficiency that results from autoimmune destruction of pancreatic islet β cells. The exact cause of T1D remains unknown, although asymptomatic islet autoimmunity lasting from weeks to years before diagnosis raises the possibility of intervention before the onset of clinical disease. The number, type, and titer of islet autoantibodies are associated with long-term disease risk but do not cause disease, and robust early predictors of individual progression to T1D onset remain elusive. The Environmental Determinants of Diabetes in the Young (TEDDY) consortium is a prospective cohort study aiming to determine genetic and environmental interactions causing T1D. Here, we analyzed longitudinal blood transcriptomes of 2013 samples from 400 individuals in the TEDDY study before both T1D and islet autoimmunity. We identified and interpreted age-associated gene expression changes in healthy infancy and age-independent changes tracking with progression to both T1D and islet autoimmunity, beginning before other evidence of islet autoimmunity was present. We combined multivariate longitudinal data in a Bayesian joint model to predict individual risk of T1D onset and validated the association of a natural killer cell signature with progression and the model's predictive performance on an additional 356 samples from 56 individuals in the independent Type 1 Diabetes Prediction and Prevention study. Together, our results indicate that T1D is characterized by early and longitudinal changes in gene expression, informing the immunopathology of disease progression and facilitating prediction of its course.The TEDDY Study is funded by U01 DK63829, U01 DK63861, U01 DK63821, U01 DK63865, U01 DK63863, U01 DK63836, U01 DK63790, UC4 DK63829, UC4 DK63861, UC4 DK63821, UC4 DK63865, UC4 DK63863, UC4 DK63836, UC4 DK95300, UC4 DK100238, UC4 DK106955, UC4 DK112243, UC4 DK117483, and Contract No. HHSN267200700014C from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institute of Allergy and Infectious Diseases (NIAID), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institute of Environmental Health Sciences (NIEHS), Centers for Disease Control and Prevention (CDC), and JDRF. This work supported in part by the NIH/NCATS Clinical and Translational Science Awards to the University of Florida (UL1 TR000064) and the University of Colorado (UL1 TR001082). KGCS is a Lister Prize fellow and is supported by a Wellcome Trust Senior Investigator award (200871/Z/16/Z). EFM is a Wellcome-Beit prize fellow (10406/Z/14/A) supported by the Wellcome Trust and Beit Foundation (10406/Z/14/Z) and by the National Institutes for Health Research Biomedical Research Centre (Cambridge). LPX’s affiliation changed after completion of the manuscript and is now Département d'informatique et de recherche opérationnelle, Université de Montréal, Montréal, Canada and Mila, Quebec Institute for Learning Algorithms, Montréal, Canada