Inhibition of iNOS expression and NO production by anti-inflammatory steroids. Reversal by histone deacetylase inhibitors.

In inflammation, nitric oxide (NO) is produced by inducible nitric oxide synthase (iNOS) induced by bacterial products and cytokines, and NO acts as a regulatory and pro-inflammatory mediator. Glucocorticoids are powerful anti-inflammatory agents that inhibit the expression of iNOS and various other inflammatory factors. Histone deacetylation has been recently described as a novel mechanism how glucocorticoids down-regulate transcriptional activation of some inflammatory genes.