The pro-inflammatory cytokines interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α, (TNF-α), and nitric oxide (NO) can be produced by activated glial cells and play a critical role in various neurological diseases. Using primary co-cultures of rat microglial and astroglial cells, we investigated the effects of the anti-inflammatory cytokines transforming growth factor-β1 (TGF-β1)/β2, IL-4, and IL-10 on the production of (pro-) inflammatory mediators after stimulation of the cells with lipopolysaccharide (LPS; 0.1 μg/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-α in a dose-dependent manner, whereas TGF-β1/β2 (2 and 20 ng/ml) only suppressed NO production. LPS-induced levels of IL-1β were suppressed by IL-10, but not by IL-4 and TGF-β1/β2. Conversely, co-incubation of the glial cells with LPS and antibodies to TGF-β1/β2 selectively enhanced LPS-induced NO production, whereas co-incubation with antibody to IL-10 enhanced LPS-induced production of all pro-inflammatory cytokines and NO. This finding strongly suggests that effective concentrations of TGF-β1/β2 and IL-10 are produced by LPS-stimulated glial cell co-cultures. Production of IL-10 in these co-cultures was confirmed by measurement of rat IL-10 by radioimmunoassay. We conclude that anti-inflammatory cytokines affect the production of inflammatory mediators in LPS-activated co-cultures of microglial and astroglial cells differentially. (C) 2000 Wiley-Liss, Inc.
Ledeboer et al. (Sat,) studied this question.