Date of Award

Fall 12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Program/Concentration

Biomedical Sciences - Microbiology & Immunology

Committee Director

Emilia Oleszak

Committee Member

Chris Platsoucas

Committee Member

Piotr Kraj

Committee Member

Alvin Holder

Abstract

Multiple Sclerosis (MS) is T-cell mediated autoimmune disease characterized by inflammation, demyelination, and degeneration of axons in the brain and spinal cord. A T cell-mediated immune response in MS is directed against myelin components and possibly other antigens in genetically susceptible individuals and is triggered by a viral infection. The T-cell antigen receptor (TCR) on T cells is responsible for antigen recognition and determines specificity. Our overall hypothesis is to determine whether clonally expanded T cells in patients with MS recognize viral or self-antigens and to determine whether molecular mimicry is involved in the development of the disease. To study TCR in MS we have developed/optimized a single-cell PCR/single-cell sequencing approach of both alpha- and beta-chain TCR, designated as Variable Region Multiplex Reverse Transcription PCR (VRM RT-PCR). We applied VRM RT-PCR for the single-cell PCR/sequencing of peripheral blood mononuclear cell (PBMC) populations and primarily memory T cells (CD3+CD8+CD45RO+, CD3+CD4+CD45RO+, and CD3+CD20+) from normal donors and patients with MS with the objective to identify clonally expanded T-cell populations. Unique TCR transcripts, when compared to each other, were observed in PBMC from normal donors in over 80% of the experiments carried out, typical of polyclonal populations of T cells. In contrast, clonally expanded T cells were identified in these T-cell populations from PBMC from patients with MS.

In other studies, we used bioinformatics approaches to determine whether there are substantial CDR3 homologies between 254 alpha- and beta-chain TCR transcripts from brain autopsy specimens or cerebrospinal fluid (CSF), previously obtained in our laboratory from six patients with MS, to alpha- and beta-chain TCR transcripts already reported in the GenBank/EMBL database. We identified extensive CDR3 region homologies between TCR expressed in brain autopsies or CSF of these six MS patients and those TCR expressed in T cells from MS patients or normal donors stimulated with myelin antigens, as well as those from patients with autoimmune diseases, Sjogren’s Syndrome, cancer, and viral infections reported in the GenBank/EMBL.

Additional studies revealed sequence homologies between myelin oligodendrocyte glycoprotein and viral peptides from several viruses, suggesting a mechanism of molecular mimicry that may be involved in MS.

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DOI

10.25777/gcmz-bz28

ISBN

9798371979872

ORCID

0000-0001-9814-7366

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