Macrophages and the glucocorticoids.

Macrophages fulfill such functions as (i) housekeeping and scavenging, (ii) protective and defense, and (iii) memory. Glucocorticoids are hormones also used as anti-inflammatory and immuno-suppressive drugs. They act on the many functions of macrophages, mainly by interfering with functions (ii) and (iii). Glucocorticoids interfere with these macrophage functions by modulating the production of inflammatory mediators such as cytokines, phospholipid-derived mediators, proteases, oxygen metabolites. For inducing these effects, glucocorticoids interact with their receptors, transcription factors that recognize specific genomic sequences, glucocorticoid responsive elements (GRE). Glucocorticoids modulate the transcription of genes in association with other transcription factors such as Fos, Jun, CREB, These combinatorial associations--differing according to the differentiation and/or activation state of the cell--may therefore produce a fine-tuning of the induction or repression of genes. These mechanisms shed new light for understanding the complexity of glucocorticoid effects on macrophage function in the inflammatory reaction.