Aldosterone abrogates nuclear factor kappaB-mediated tumor necrosis factor alpha production in human neutrophils via the mineralocorticoid receptor.

Mineralocorticoid receptor (MR) activation by aldosterone controls salt homeostasis and inflammation in several tissues and cell types. Whether or not a functional MR exists in polymorphonuclear neutrophils is unknown. We investigated the hypothesis that aldosterone modulates inflammatory neutrophil responses via the MR. By flow cytometry, Western blot analysis, and microscopy, we found that neutrophils possess MR. Preincubation with aldosterone (10(-11) to 10(-6) M) dose-dependently inhibited nuclear factor kappaB activation in interleukin (IL)-8- and granulocyte/macrophage colony-stimulating factor-treated neutrophils on fibronectin by IkappaBalpha Western blotting, electrophoretic mobility shift assay, and RT-PCR for IkappaBalpha mRNA. Aldosterone had no effect on tumor necrosis factor alpha- and lipopolysaccharide-mediated nuclear factor kappaB activation or on IL-8- and granulocyte/macrophage colony-stimulating factor-induced extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, or phosphatidylinositol 3-kinase/Akt activation. Spironolactone prevented nuclear factor kappaB inhibition, indicating an MR-specific aldosterone effect. By RT-PCR, we found that neutrophils have 11beta-hydroxysteroid dehydrogenase. Tumor necrosis factor alpha, which is controlled by nuclear factor kappaB, increased in the cell supernatant with IL-8 treatment. Aldosterone completely prevented this effect. RT-PCR showed a strong tumor necrosis factor alpha mRNA increase with IL-8 that was blocked by aldosterone, excluding the possibility that the tumor necrosis factor alpha increase was merely a consequence of secretion. Finally, conditioned medium from IL-8-treated neutrophils increased intercellular adhesion molecule-1 expression on endothelial cells and subsequently the adhesion of IL-8-treated neutrophils to endothelial cells. These effects were reduced when conditioned medium from aldosterone-pretreated neutrophils was used, and spironolactone blocked the aldosterone effect. Our data indicate that a functional MR exists in neutrophils mediating antiinflammatory effects that are at work when neutrophils interact with endothelial cells. These data could be relevant to MR-blockade treatment protocols.