Mouse embryonic stem (ES) cells differentiate into cells of all three primary germ layers including endodermal cells that produce insulin in vitro.We show that constitutive expression of Pax4 (Pax4 ؉ ), and to a lesser extent Pdx1 (Pdx1 ؉ ), affects the differentiation of ES cells and significantly promote the development of insulin-producing cells. In Pax4 overexpressing R1 ES cells, isl-1, ngn3, insulin, islet amyloid polypeptide, and glucose transporter 2 (Glut-2) mRNA levels increase significantly. The number of nestinexpressing (nestin؉) cells also increases. Constitutive Pax4 expression combined with selection of nestin؉ cells and histotypic culture conditions give rise to spheroids containing insulin-positive granules typical of embryonal and adult  cells. In response to glucose, Pax4 ؉ and wild-type ES-derived cells release insulin. Transplantation of these cells into streptozotocin-treated diabetic mice results in a normalization of blood glucose levels. We conclude that constitutive expression of Pax4 in combination with histotypic cultivation facilitates ES cell differentiation into the pancreatic lineage, which leads to the formation of islet-like spheroid structures that produce increased levels of insulin.
Immunoprecipitating IgG autoantibodies to glutamic acid decarboxylase, GAD 65 , and/or a tyrosine phosphatase, IA2, are present in the majority of individuals experiencing pancreatic  cell destruction and development of type 1 diabetes. Here we identify a third islet cell autoantigen, a novel 38-kD protein, which is specifically immunoprecipitated with sera from a subset of prediabetic individuals and newly diagnosed type 1 diabetic patients. The 38-kD autoantigen, named glima 38, is an amphiphilic membrane glycoprotein, specifically expressed in islet and neuronal cell lines, and thus shares the neuroendocrine expression patterns of GAD 65 and IA2. Removal of N-linked carbohydrates results in a protein of 22,000 M r . Glima 38 autoantibodies were detected in 16/86 (19%) of newly diagnosed patients, including three very young children, who had a rapid onset of disease, and in 6/44 (14%) of prediabetic individuals up to several years before clinical onset. The cumulative incidence of GAD 65 and glima 38 antibodies in these two groups was 83 and 80%, respectively, and the cumulative incidence of GAD 65
A screening strategy based on the analysis of antibodies to multiple islet antigens can predict IDDM at high sensitivity and specificity in families, and such a strategy may also be applicable to identify young individuals in the general population with high disease risk. Since appearance of antibodies to different antigens occurs sequentially rather than simultaneously, accurate assessment of diabetes risk based on the presence of multiple antibodies will require follow-up over a number of years after the first evidence of islet autoimmunity.
IDDM results from immune-mediated destruction of insulin-producing pancreatic beta-cells in individuals genetically susceptible for the disease. There is evidence that the 65-kDa isoform of GAD plays a critical role in the induction of autoimmune diabetes in NOD mice. In humans, it is still unclear when and to what beta-cell antigens autoreactive lymphocytes become activated during early disease. We conducted a prospective study from birth, BABY-DIAB, among children of mothers with IDDM or gestational diabetes or fathers with IDDM, and we investigated the temporal sequence of antibody responses to islet cells (ICA), insulin (IAA), GAD (GADA), and the protein tyrosine phosphatase IA-2/ICA512 (IA-2A). Of 1,019 children included at birth, we have currently followed 513 to the age of 9 months, 214 to the age of 2 years, and 37 to the age of 5 years. At birth, all antibody specificities were frequent in newborns of diabetic mothers but not fathers and are suggested to be transplacentally acquired because they are strongly correlated with antibody levels in their diabetic mothers. In early childhood, antibody levels were <99th percentile of control subjects in the majority of children. However, 37 children exhibited elevated antibody levels; these were most frequently detected at the age of 2 years. The antibody prevalence at age 2 years was 2.3% for ICA, 7% for IAA, 4.2% for GADA, and 2.8% for IA-2A (8.9% positive for at least one antibody). Children of diabetic fathers were positive for at least one antibody more frequently than were children of diabetic mothers (9 months of age: 8.5 vs. 3.6%; 2 years of age: 16.7 vs. 7.9%). There was no specific sequence in the appearance of positive autoantibodies, but 13 (35%) antibody-positive cases already had more than one ICA before the age of 2 years and 7 (19%) showed reactivity to three islet cell antigens before age 5 years. The presence of multiple antibodies confers high risk for the future development of diabetes; three of six children who exhibited positive antibody responses to all four antibodies tested and another child with two positive antibodies developed clinical diabetes at the ages of 13, 21, and 27 months and 5 years. We conclude that loss of tolerance to beta-cell autoantigens and appearance of autoimmune phenomena occur very early in life in individuals with genetic susceptibility for IDDM. Screening programs to identify candidates for disease-prevention therapies can therefore be focused on this young age-group, in whom the disease process may be less advanced and who may therefore be best suited to such therapies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.