Glucocorticoids exert opposing effects on macrophage function dependent on their concentration

Abstract

Glucocorticoids (GCs) are involved in the modulation of macrophage function and thereby control the host's immune responses to pathogens. However, neither the role of hormone concentration nor the differential contribution of the glucocorticoid (GR) and the mineralocorticoid receptors (MR) to these activities are known. Here we show that low levels of corticosterone enhance NO production as well as mRNA expression of pro-inflammatory cytokines, chemokines and enzymes required for mediator synthesis. In contrast, at high corticosterone concentrations macrophage function was strongly repressed. Importantly, inactivation of the GR by lentiviral delivery of siRNAs abrogated both the immunostimul..