Stress-induced enhancement of NF-κB DNA-binding in the peripheral blood leukocyte pool: effects of lymphocyte redistribution

Abstract

To identify signaling pathways by which the sympathetic nervous system (SNS) might alter gene expression in the immune system, we assayed activation of the inflammatory transcription factor NF-κB in peripheral blood mononuclear cells (PBMC) from 13 healthy young adults at rest and following 5 min of intense exercise. SNS activation was verified by changes in cardiovascular parameters and mobilization of NK cells into circulating blood. Electrophoretic mobility shift assays (EMSA) of nuclear protein extracts confirmed previous findings that SNS activation increased NF-κB DNA-binding activity in bulk PBMC. However, analyses of isolated leukocyte subsets failed to indicate any increase on a per-cell basis in NK cells (the major carriers of NF-κB activity in circulating PBMC), in the residual CD56− leukocyte pool, or in CD14+ monocytes. Regression analyses indicated a strong correlation between increasing NK cell prevalence and changes in NF-κB DNA-binding activity in bulk PBMC, and suggested that no change in EMSA activity would be observed in the absence of NK cell mobilization. Such results imply that SNS-induced mobilization of NK cells can rapidly (<10 min) alter NF-κB DNA-binding activity in the circulating PBMC pool without generating any true change in NF-κB activity on a per-cell basis. Implications for future efforts to analyze stress effects on leukocyte gene expression are considered.