Interleukin-10, interleukin-4, and transforming growth factor-beta differentially regulate lipopolysaccharide-induced production of pro-inflammatory cytokines and nitric oxide in co-cultures of rat astroglial and microglial cells

The pro-inflammatory cytokines interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) can be produced by activated glial cells and play a critical role in various neurological dis eases. Using primary co-cultures of rat microglial and astroglial cells, we investigated the effects of the anti-inflammatory cytokines transforming g rowth factor-beta 1 (TGF-beta 1)/beta 2, IL-4, and IL-10 on the production of (pro-) inflammatory mediators after stimulation of the cells with lipopo lysaccharide (LPS; 0.1 mu g/ml, 24 h). IL-10 (10 and 100 ng/ml) and IL-4 (5 and 50 U/ml) suppressed the LPS-induced production of NO, IL-6, and TNF-al pha in a dose-dependent manner, whereas TGF-beta 1/beta 2 (2 and 20 ng/ml) only suppressed NO production. LPS-induced levels of IL-1 beta were suppres sed by IL-10, but not by IL-4 and TGF-beta 1/beta 2, Conversely, co-incubat ion of the glial cells with LPS and antibodies to TGF-beta 1/beta 2 selecti vely enhanced LPS-induced NO production, whereas co-incubation with antibod y to IL-10 enhanced LPS-induced production of all pro-inflammatory cytokine s and NO. This finding strongly suggests that effective concentrations of T GF-beta 1/beta 2 and IL-10 are produced by LPS-stimulated glial cell co-cul tures, Production of IL-10 in these co-cultures was confirmed by measuremen t of rat IL-10 by radioimmunoassay. We conclude that anti-inflammatory cyto kines affect the production of inflammatory mediators in LPS-activated co-c ultures of microglial and astroglial cells differentially. GLIA 30:134-142, 2000. (C) 2000 Wiley-Liss, Inc, Inc.