Date of Award

2017

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Microbiology and Immunology

Abstract

It is well-established that psychological stress reduces natural killer (NK) cell immune function. This reduction is mediated by stress-induced release of glucocorticoids (GC), which can suppress immune function. Associated with suppression of a particular immune function are GC induced histone-epigenetic marks. Histone-epigenetic marks are responsible for the organization and compartmentalization of genomes into transcriptionally active euchromatin domains that are localized to the interior of the nucleus. Transcriptionally silent heterochromatic domains are enriched with methylated epigenetic marks and are localized to the nuclear periphery. The purpose of this investigation was to assess the influence of GC on H3K27me3 chromatin organization by measurement of that repressive epigenetic mark. As well as the relationship of H3K27me3 chromatin organization to NK cell effector function, i.e. interferon (IFN) gamma production, was determined. IFN gamma was selected because it is the prototypic cytokine produced by NK cells and is known to modulate both innate and adaptive immunity. GC treatment of human peripheral blood mononuclear cells significantly reduced IFN gamma production. GC treatment produced a distinct NK cell H3K27me3 chromatin organization phenotype. This phenotype was localization of the histone post-translational epigenetic mark, H3K27me3, to the nuclear periphery and was directly related to the reduced production of IFN gamma by NK cells. This nuclear phenotype was determined by direct visual inspection and by use of an automated, high through-put technology, the Amnis ImageStream. This technology combines the per-cell information content provided by standard microscopy with the statistical significance afforded by large sample sizes common to standard flow cytometry. Most importantly, this technology provided for direct assessment of the localization of H3K27me3 within individual nuclei. These results demonstrate GC to reduce NK cell function at least in part through altered H3K27me3 nuclear organization and suggests that H3K27me3 chromatin organization may be a predictive measure of GC induced immune dysregulation in NK cells.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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