Biomedical subjects

Edwin Liu

Publications and source records attributed to Edwin Liu.

25 records · Page 2Linked to original sources

PubMed2003

Establishing insulin 1 and insulin 2 knockout congenic strains on NOD genetic background.

As insulin is a major autoantigen in autoimmune diabetes and because the insulin gene region locus in humans has been linked to diabetes risk, we have bred insulin gene knockouts onto the NOD mouse. Mice differ from humans in terms that they express two nonallelic genes of insulin. Insulin 2 is the murine homologue of the human insulin gene and is located on mouse chromosome 7. Insulin 1 is thought to have evolved by a gene duplication event, lacks the second intron of the insulin 2 gene, and is located on mouse chromosome 19. The differential thymic expression of the insulin gene may be important for central tolerance induction. Here, we present the initial establishment of congenic knockouts and characterization of the congenic intervals corresponding to insulin 1 and insulin 2 knockout genes on mouse chromosome 19 and 7, respectively.

Animals↗

PubMed2003

In vivo expression of B:9-23 peptide/I-A(g7) complex may abrogate the inhibition of diabetes induced by RGD-fiber-mutant adenovirus in NOD mice.

Insulin B chain peptide B:9-23 given to NOD mice decreases the development of diabetes, and phase II trials of an altered peptide ligand of B:9-23 are under way in humans. We have created a gene for the NOD MHC class II beta chain, covalently linked to the B:9-23 peptide. B lymphoma cells transfected with the gene stimulated NOD islet-derived B:9-23 reactive T cell clones in vitro. In this study, we generated an RGD-fiber-mutant adenovirus vector encoding the covalent B:9-23 peptide/I-A(g7) gene (Ad-RGD-B:9-23) to test whether in vivo expression of the gene could protect NOD mice from diabetes. NOD female mice were injected intramuscularly with 5 x 10(8) PFU of Ad-RGD-B:9-23 and empty RGD-adenovirus vector. A single administration of the empty vector did not alter the expression of insulin autoantibodies, but delayed the onset of diabetes in NOD mice. In contrast, Ad-RGD-B:9-23 immunization induced an early expression of insulin autoantibodies, but did not change the disease occurrence compared to control NOD mice. Our results suggest that adenovirus infection could confer protection from diabetes in NOD mice. The in vivo expression of covalent B:9-23 peptide/class II complex by adenovirus gene transfer might activate anti-insulin autoimmunity, resulting in abrogation of the inhibition of diabetes induced by an RGD-fiber-mutant adenovirus vector.

Adenoviridae↗

PubMed2002

Induction and acceleration of insulitis/diabetes in mice with a viral mimic (polyinosinic-polycytidylic acid) and an insulin self-peptide.

Polyinosinic-polycytidylic acid (PolyIC), a "mimic" of double-stranded viral RNA, can induce diabetes when administered to rats with RT1(u), and immunization of normal H-2(d) mice (e.g., BALB/c) with insulin B:9-23 peptide (but not H-2(b)) results in the rapid induction of insulin autoantibodies. Because a mouse model of PolyIC/antigen-induced diabetes is lacking, we sought to produce insulitis and diabetes with either PolyIC and/or B:9-23 peptide immunization. Simultaneous administration of PolyIC and B:9-23 peptide to BALB/c mice (but with neither alone) induced insulitis. CD4 T lymphocytes predominated within islets, and the mice did not progress to hyperglycemia. Islets with transgene-induced expression of the costimulatory B7-1 molecule have enhanced diabetes susceptibility. Diabetes was frequently induced in B7-1 transgenic mice with H-2(d) in contrast to H-2(b) mice after PolyIC administration. Disease induction was accelerated by adding B:9-23 immunization to PolyIC. These studies demonstrate that "normal" mice have autoreactive T lymphocytes able to rapidly target islets and insulin given appropriate MHC alleles and that a peripherally administered insulin peptide (an altered peptide ligand of which is in clinical trials) can enhance specific anti-islet autoimmunity. These first PolyIC/insulin-induced murine models should provide an important tool to study the pathogenesis of type 1 diabetes with experimental autoimmune diabetes.

Alleles↗

PubMed2002

Type 1A diabetes mellitus-associated autoimmunity.

Type 1A diabetes mellitus has become one of the most intensively studied autoimmune disorders, with characterized animal models and extensive prospective studies of the development of anti-islet autoimmunity. It is now possible to predict the development of type 1A diabetes mellitus, beginning with HLA-encoded genetic susceptibility, followed by the development of a series of anti-islet autoantibodies. Prediction primarily is based on the detection of multiple anti-islet autoantibodies reacting with cloned islet antigens. Multiple international workshops fostered the development of specific and sensitive radioassays for autoantibodies reacting with GAD65 (glutamic acid decarboxylase), ICA512 (also termed IA-2, a tyrosine phosphatase-like protein), and insulin. Similar high throughput radioassays have been applied using autoantigens for additional autoimmune disorders including celiac disease and Addison's disease. Relatives of patients with type 1A diabetes mellitus inherit susceptibility to express multiple autoantibodies, and a subset of autoantibody-positive individuals inherit susceptibility to progress to overt disease. This article reviews autoimmune disorders associated with type 1A diabetes mellitus.

Addison Disease↗

PubMed2002

Insulin autoimmunity: prediction/precipitation/prevention type 1A diabetes.

Type 1 diabetes of both the NOD mouse and man is associated with autoimmunity directed against insulin which is the only beta cell specific autoantigen identified to date. One can use autoantibodies to insulin to predict diabetes, use insulin peptides to create insulin autoantibodies, insulitis and diabetes, and use insulin or its peptides in animal models to prevent diabetes. An expanding set of resources are now available for the development and testing in man of therapies to prevent type 1 diabetes, and a number of trials utilizing insulin peptides are now underway.

Animals↗

PubMed2002

Induction of insulin autoantibodies and protection from diabetes with subcutaneous insulin B:9-23 peptide without adjuvant.

Insulin B chain peptide B:9-23 given with incomplete Freund's adjuvant (IFA) subcutaneously to NOD and BALB/c mice induces insulin autoantibodies (IAA). We also found that subcutaneous administration of the peptide without adjuvant induced IAA in normal BALB/c mice. The autoantibodies react with intact insulin and cannot be absorbed by the B:9-23 peptide. With the induction of IAA by the self-peptide without adjuvant, we hypothesized that the peptide given subcutaneously without adjuvant would prevent the development of diabetes mellitus in NOD mice. The peptide B:9-23, when given in standard doses of 100 microg and low doses of 10 microg, protected female NOD mice versus unvaccinated controls from diabetes. Presently, NOD mice vaccinated with the standard dose and the low dose have a 44% and 60% survival, respectively, at 26 weeks compared to controls with a 10% diabetes-free survival at 22 weeks (n = 10 for each group, P < 0.001 for both vaccine doses). As expected, the level of IAA expressed was significantly higher for the vaccinated mice versus the control group. We conclude that insulin B chain peptide B:9-23 can confer protection from diabetes in NOD mice even when administered subcutaneously without adjuvant.

Adjuvants, Immunologic↗

PubMed2002

Anti-peptide autoantibodies and fatal anaphylaxis in NOD mice in response to insulin self-peptides B:9-23 and B:13-23.

There is evidence that amino acids 9-23 of the insulin B chain are a major target of anti-islet autoimmunity in type 1 diabetes. Administration of this peptide to NOD mice prevents diabetes, and phase I trials of an altered peptide ligand of B:9-23 are underway in humans. We were interested in long-term subcutaneous therapeutic administration of B:9-23 without adjuvant. To our initial surprise, the peptide consistently induced fatal anaphylaxis in NOD mice after 6 weeks of administration. Anaphylaxis could be blocked by a combination of antihistamine and platelet-activating factor antagonist (but neither alone) or by a combination of anti-IgG receptor and anti-IgE antibodies. High titers of anti-B:9-23 antibodies were induced within 3-4 weeks of immunization with the peptide. Peptide B:13-23 also induced anaphylaxis and was more potent than peptide B:9-23. Antibodies induced by peptide B:9-23 and peptide B:13-23 did not cross-react with each other. Thus, the insulin peptides B:9-23 and B:13-23, even when administered subcutaneously in the absence of adjuvant, can induce a dramatic humoral response leading to fatal anaphylaxis in NOD mice.

Anaphylaxis↗