Antigen Specific Cd4+ T Cell Responses Against A Gastrointestinal Nematode

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Degree type
Doctor of Philosophy (PhD)
Graduate group
Immunology
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CD4+ T helper cells
Parasitic nematode
Regulatory T cells
Strongyloides ratti
Transgenesis
Type 2 immunity
Allergy and Immunology
Immunology and Infectious Disease
Medical Immunology
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2022-09-17T20:21:00-07:00
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Douglas, Bonnie Douglas
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Abstract

Helminths are distinct from microbial pathogens in terms of size and complexity, and are likely the evolutionary driving force for type 2 immunity. CD4+ helper T cells can both coordinate worm clearance and prevent immunopathology, but issues of T cell antigen specificity in the context of helminth-induced Th2 and T regulatory cell (Treg) responses have not been addressed. Herein, a novel transgenic line of the gastrointestinal nematode Strongyloides ratti was generated that expresses the immunodominant CD4+ T cell epitope 2W1S as a fusion protein with green fluorescent protein (GFP) and FLAG peptide in order to track and study helminth-specific CD4+ T cells. C57BL/6 mice infected with this stable transgenic line (termed Hulk) underwent a dose-dependent expansion of activated CD44+CD11a+ 2W1S-specific CD4+ T cells, preferentially in the lung parenchyma. Transcriptional profiling of 2W1S-specific CD4+ T cells isolated from mice infected with either Hulk or the enteric bacterial pathogen Salmonella expressing 2W1S revealed that pathogen context exerted a dominant influence over CD4+ T cell phenotype. Interestingly, Hulk-elicited 2W1S-specific CD4+ T cells exhibited both Th2 and Treg phenotypes and expressed high levels of the EGFR ligand amphiregulin, which differed greatly from the phenotype of 2W1S-specific CD4+ T cells elicited by 2W1S-expressing Salmonella. While immunization with 2W1S peptide did not enhance clearance of Hulk infection, immunization did increase total amphiregulin production as well as the number of amphiregulin-expressing CD3+ cells in the lung following Hulk infection. Altogether, this new model system reveals that helminth-specific CD4+ T cells can adopt effector as well as immunosuppressive and wound reparative phenotypes. This report establishes a new resource for studying the nature and function of helminth-specific T cells.

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De'Broski R. Herbert
Date of degree
2021-01-01
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