Expression of GAD67 and Novel GAD67 Splice Variants During Human Fetal Pancreas Development: GAD67 Expression in the Fetal Pancreas

Glutamic acid decarboxylase (GAD) is a major inhibitory neurotransmitter in the brain, which catalyses the reaction of l-glutamate to γ-aminobutyric acid. There are two isoforms of GAD, a 65-kDa form and a 67-kDa form, which are encoded by two different genes. As previous studies suggested a role for GAD67 splice variants during fetal pancreas development, we have investigated the mRNA expression of GAD67 and GAD67 splice variants in a series of 14 human fetal pancreases between 14 weeks gestation and term and in adult control pancreases by RT-PCR. In this study, we demonstrate mRNA expression of GAD67 and four GAD67 splice variants, including GAD25, in human fetal and adult specimens. Some of the splice variants, including various proportions of exon 7 or a new exon between exons 6 and 7, have not been described before in the human pancreas. We speculate that the expression of these GAD67 splice variants might be related to human fetal pancreas development

Decline in Titers of Anti-Idiotypic Antibodies Specific to Autoantibodies to GAD65 (GAD65Ab) Precedes Development of GAD65Ab and Type 1 Diabetes.

The humoral Idiotypic Network consisting of antibodies and their anti-idiotypic antibodies (anti-Id) can be temporarily upset by antigen exposure. In the healthy immune response the original equilibrium is eventually restored through counter-regulatory mechanisms. In certain autoimmune diseases however, autoantibody levels exceed those of their respective anti-Id, indicating a permanent disturbance in the respective humoral Idiotypic Network. We investigated anti-Id directed to a major Type 1 diabetes (T1D)-associated autoantibody (GAD65Ab) in two independent cohorts during progression to disease. Samples taken from participants of the Natural History Study showed significantly lower anti-Id levels in individuals that later progressed to T1D compared to non-progressors (anti-Id antibody index of 0.06 vs. 0.08, respectively, p = 0.02). We also observed a significant inverse correlation between anti-Id levels and age at sampling, but only in progressors (p = 0.014). Finally, anti-Id levels in progressors showed a significant decline during progression as compared to longitudinal anti-Id levels in non-progressors (median rate of change: -0.0004 vs. +0.0004, respectively, p = 0.003), suggesting a loss of anti-Id during progression. Our analysis of the Diabetes Prediction in Skåne cohort showed that early in life (age 2) individuals at risk have anti-Id levels indistinguishable from those in healthy controls, indicating that low anti-Id levels are not an innate characteristic of the immune response in individuals at risk. Notably, anti-Id levels declined significantly in individuals that later developed GAD65Ab suggesting that the decline in anti-Id levels precedes the emergence of GAD65Ab (median rate of change: -0.005) compared to matched controls (median rate of change: +0.001) (p = 0.0016). We conclude that while anti-Id are present early in life, their levels decrease prior to the appearance of GAD65Ab and to the development of T1D

Antigen-specific dose-dependent system for the study of an inheritable and reversible phenotype in mouse CD4(+) T cells

The transgenic T-cell receptor in mouse TEa CD4(+) lymphocytes recognizes an endogenous peptide, Eα52-68, presented in the context of the major histocompatibility complex class II molecule I-A(b). In response to an optimal peptide concentration TEa cells enter the cell cycle and proliferate. However, a single exposure to high doses of the specific peptide diminished cell expansion upon subsequent restimulation. This hyporesponsive, or anergic, phenotype can still be detected after multiple restimulations indicating that the hyporesponsiveness persists despite cell division and it was inherited by daughter cells. Furthermore, we demonstrated that this hypoproliferative response is associated with high p27(Kip1) and cyclin E protein levels, and reduced intracellular interleukin-2 (IL-2) expression. Addition of exogenous IL-2 was required to reset p27(Kip1) levels in the progeny derived from hyporesponsive TEa cells. Thus, we have established antigen dose-dependent induction of a reversible, inheritable (i.e. epigenetic) phenotype and we have identified at least three components of the network of interactions: p27(Kip1) cyclin E, and IL-2 expression

How to diagnose and classify diabetes in primary health care: Lessons learned from the Diabetes Register in Northern Sweden (DiabNorth)

OBJECTIVE: The objective was to create a diabetes register and to evaluate the validity of the clinical diabetes diagnosis and its classification. DESIGN: The diabetes register was created by linkage of databases in primary and secondary care, the pharmaceutical database, and ongoing population-based health surveys in the county. Diagnosis and classification were validated by specialists in diabetology or general practitioners with special competence in diabetology. Analysis of autoantibodies associated with type 1 diabetes was used for classification. Setting. Primary and secondary health care in the county of Västerbotten, Sweden. PATIENTS: Patients with diabetes (median age at diagnosis 56 years, inter quartile range 50–60 years) who had participated in the Västerbotten Intervention Programme (VIP) and accepted participation in a diabetes register. RESULTS: Of all individuals with diabetes in VIP, 70% accepted to participate in the register. The register included 3256 (M/F 1894/1362) diabetes patients. The vast majority (95%) had data confirming the diabetes diagnoses according to WHO recommendations. Unspecified diabetes was the most common (54.6%) classification by the general practitioners. After assessment by specialists and analysis of autoantibodies the majority were classified as type 2 diabetes (76.8%). Type 1 diabetes was the second largest group (7.2%), including a sub-group of patients with latent autoimmune diabetes (4.8%). CONCLUSION: It was concluded that it is feasible to create a diabetes register based on information in medical records in general practice. However, special attention should be paid to the validity of the diabetes diagnosis and its classification