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It is well-established that psychological distress reduces natural killer cell activity (NKCA) and dysregulates cytokine balance. This maybe mediated by stress-induced release of glucocorticoids, which have broad effects on the immune system, including the suppression of NKCA and alteration of cytokine production. The purpose of this study was to evaluate epigenetic mechanisms that may underlie the effect of glucocorticoids on NK cells, using the human NK cell line, NK92. Treatment of NK92 cells with the synthetic glucocorticoid, dexamethasone, at a concentration of 10 −7 M, produced a significant reduction in NKCA. Glucocorticoid inhibition was a consequence of not only a reduced capacity of the NK cells to bind to tumor targets but also a reduced production of granule constituents (perforin and granzyme B) with no detectable effect on granule exocytosis. Glucocorticoids also reduced the constitutive and the stimulated production of the cytokines, IL-6, TNF alpha and IFN gamma, and reduced the surface expression of LFA-1. Glucocorticoid treatment also reduced global histone acetylation, the acetylation of histone 4 lysine position 8, and the accessibility of the proximal promoters of perforin, interferon gamma and granzyme B. Histone acetylation was recovered by treatment of the NK cells with a histone deacetylase inhibitor, which also restored NKCA and IFN gamma production. These results demonstrate glucocorticoids to dysregulate NK cell function at least in part through an epigenetic mechanism, which reduces promoter accessibility through modification of histone acetylation status. This epigenetic modification decreases the expression of effector proteins necessary to the full functional activity of NK cells.

Women respond differentially to the stress-associated with breast cancer diagnosis and treatment, with some women experiencing more intense and/or sustained behavioral symptoms and immune dysregulation than others. Childhood adversity has been identified to produce long-term dysregulation of stress response systems, increasing reactivity to stressors encountered during adulthood. This study determined whether childhood adversity increased vulnerability for more intense and sustained behavioral symptoms (fatigue, perceived stress, and depressive symptoms), poorer quality of life, and greater immune dysregulation in women (N=40) with breast cancer. Evaluation was after breast surgery and through early survivorship. Hierarchical linear modeling was used to examine intra-individual and inter-individual differences with respect to initial status and to the pattern of change (i.e. trajectory) of outcomes. At initial assessment, women exposed to childhood emotional neglect/abuse had greater perceived stress, fatigue, depressive symptoms and poorer quality of life, as well as lower natural killer cell activity (NKCA). Although these outcomes improved over time, women with greater childhood emotional neglect/abuse exhibited worse outcomes through early survivorship. No effect was observed on the trajectory for these outcomes. In contrast, childhood physical neglect predicted sustained trajectories of greater perceived stress, worse quality of life, and elevated plasma IL-6; with no effect observed at initial assessment. Thus, childhood adversity leaves an enduring imprint, increasing vulnerability for behavioral symptoms, poor quality of life, and elevations in IL-6 in women with breast cancer. Further, childhood adversity predisposes to lower NKCA at a critical time when this immune-effector mechanism is most effective at halting nascent tumor seeding.