The neuroprotective agents chlomethiazole and SB203580 inhibit IL-1beta signalling but not its biosynthesis in rat cortical glial cells.

Chlomethiazole and pyridinyl imidazole compounds, exemplified by SB203580, are structurally distinct p38 mitogen-activated protein kinase inhibitors with neuroprotective properties in models of cerebral ischaemia. We have examined their effects in interleukin-1beta (IL-1beta) synthesis, release and signalling in rat cortical glial cells, given the important role of IL-1beta in cerebral ischaemia. We analysed (i) IL-1beta mRNA expression by northern blot, (ii) IL-1beta protein precursor levels within the cells by western blot, and (iii) the levels of the mature IL-1beta protein secreted into the medium by enzyme-linked immunosorbent assay (ELISA) after treatment of rat cortical glial cells with lipopolysaccharide. While the induction of IL-1beta expression by lipopolysaccharide or by IL-1beta itself was very sensitive to nuclear factor kappa B (NF-kappaB) inhibitors, chlomethiazole or SB203580 were nearly without effect, indicating a differential regulation as compared to peripheral cells, e.g. monocytes. In contrast, chlomethiazole and SB203580 potently inhibited the IL-1beta-induced expression of c-fos and inducible nitric oxide synthase, as monitored by northern blot and quantitative RT-PCR, respectively. Because IL-1beta-induced expression of c-fos and inducible nitric oxide synthase is believed to directly contribute to the pathology of cerebral ischaemic injury, the results suggest a direct mechanism for the neuroprotective effects of chlomethiazole and SB203580, and further establish the anti-inflammatory properties of chlomethiazole.