Dissertation
Germline-encoded T-cell receptor sequences are a determinant of diabetes susceptibility and islet-antigen recognition in the LEW.1WR1 rat model of Type-1 diabetes
Doctor of Philosophy (Ph.D.), Drexel University
Apr 2013
DOI:
https://doi.org/10.17918/00000695
Abstract
Our previous studies identified a T-cell receptor variable region, TCRV1313, as the genetic element underlying Iddm14, a strong quantitative trait locus (QTL) for rat autoimmune diabetes. Depletion of V[beta]13+ T-cells with an allele-specific monoclonal antibody (17D5) prevents diabetes in multiple rat models. To better understand the role of V1313 in diabetes, we examined islet T-cell transcripts in susceptible (LEW.1WR1) and resistant (LEW.1W and WF) strains treated with polyinosinic:polycytidylic acid (poly I:C) to induce disease. As T-cells clonally expand in response to antigen significant narrowing of TCR diversity, termed antigen focusing, occurs. V[beta]13+ T-cells showed substantial antigen focusing in LEW.1WR1 islets five days post induction characterized by a substantial decrease in CDR3 diversity. No transcripts of any TCR-VP isotype are antigen focused in LEW.1WR1 islets 4 days post induction indicating that V[beta]13+ T-cells contribute to the earliest antigen-specific event in diabetes development. V[beta]13 antigen focusing occurs prior to significant islet T-cell accumulation (day 7) or frank diabetes (day 10-14). V[beta]13+ transcripts increase in LEW.1WR1 islets during diabetes progression, whereas no T-cell transcripts of any TCR isotype accumulate in the islets of resistant rats during the same time. T-cell infiltration of LEW.1WR1 islets (Day7) is concurrent with insulin transcript upregulation suggesting [beta] cell damage and compensatory up-regulation of de-novo insulin synthesis. We also analyzed transcript clonality of rat TCR-Va5, ortholog of the dominant TCR-Va chain found on insulin B:9-23- reactive T-cells in NOD islets. TCR-Va5+ transcripts accumulate and clonal expand in pre-diabetic LEW.1WR1 islets, suggesting that rat Va5 also contributes to recognition islet autoantigen, presumably insulin B:9-23. Together these data provide additional evidence that genome-encoded TCR sequences are important determinants of genetic susceptibility to T1 D. Lastly, Iddm37, another important diabetes QTL, conditions rat diabetes susceptibility to poly I:C or KRV infection. Diubiquitin ( UBD) is a strong candidate gene in this interval. An orthologous susceptibility locus was identified in people bearing high-risk HLA-DR3/4 haplotypes. We sequenced human UBD from case and control subjects and identified a UBD promoter SNP that was significantly associated with latency to islet autoantibody development. This suggests that UBD may be important for diabetes susceptibility to environmental triggers in man.
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Details
- Title
- Germline-encoded T-cell receptor sequences are a determinant of diabetes susceptibility and islet-antigen recognition in the LEW.1WR1 rat model of Type-1 diabetes
- Creators
- Ryan Anthony Eberwine
- Contributors
- Elizabeth P. Blankenhorn (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- ix, 190 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 991014970223604721