Inflammatory cytokine release of astrocytes in vitro is reduced by all-trans retinoic acid

In the central nervous system inflammation is mediated by microglia and astrocytes. To investigate its regulation, murine astrocyte cultures were treated with bacterial lipopolysaccharides (LPS) and analyzed with Affymetrix gene array, qRT-PCR and ELISA. Cells responded to LPS with a strong upregulation of pro-inflammatory cytokines and chemokines. Treatment with the transcriptional activator retinoic acid (RA) suppressed mRNA expression and protein release of several important cytokines (IL-1β 4%, IL-6 21%, TNFα 30%, IL-12p40 42%, and IL-12p35/p40 27%; p < 0.01). The data are consistent with the hypothesis that all-trans RA takes part in endogenous anti-inflammatory feedback loops in the CNS.