Production of interleukin-1 and tumour necrosis factor from stimulated human monocytes is inhibited by a new series of pyridinyl-imidazole compounds. Using radiolabelled and radio-photoaffinity-labelled chemical probes, the target of these compounds was identified as a pair of closely related mitogen-activated protein kinase homologues, termed CSBPs. Binding of the pyridinyl-imidazole compounds inhibited CSBP kinase activity and could be directly correlated with their ability to inhibit cytokine production, suggesting that the CSBPs are critical for cytokine production.

Thus, these novel compounds offer a new disease modifying therapy for arthritis and the results also suggest that inhibition of TNF alpha production may contribute, at least in part, to their anti-arthritic activity.

No abstract

Exposure of human monocytes (HM) to E. coli lipopolysaccharide (LPS) results in measurable production of both IL-1 beta and TNF alpha in culture supernatants. It has previously been reported that the elevation of cAMP levels in HM selectively suppresses the LPS-induced TNF alpha but not IL-1 beta production. In this study we investigated whether the novel anti-inflammatory drug, SK&F 86002 [5-4(-pyridyl)-6(4-fluorophenyl)-2,3-dihydroimidazole(2,1-b)thi azol] and related analogs of the pyridinyl imidazole class, inhibit IL-1 and TNF production via a cAMP-dependent mechanism. These compounds, when added together with LPS result in inhibition of IL-1 and TNF production with equal-rank-order potency. Although the pyridinyl imidazole compounds were found to be generally weak phosphodiesterase inhibitors, they did not affect cAMP levels in HM, alone or in the presence of LPS. In contrast, PGE2, which significantly elevated intracellular cAMP levels, inhibited TNF but not IL-1 production at the transcriptional level. Taken together, these results suggest that the pyridinyl imidazoles inhibit the production of IL-1 beta and TNF alpha through pathways independent of cAMP elevating mechanisms.

Abstract. The effects of bicyclic imidazoles on human monocyte and endothelial cell cytokine production were examined. These compounds constitute the CSAID TM class of anti-inflammatories and are inhibitors of cytokine biosynthesis. The bicyclic imidazoles differ from glucocorticoids and phosphodiesterase inhibitors in their chemical structure as well as pharmacological profile. At optimal concentrations of LPS (50 ng/ml), SK&F 86002, a prototypic compound, inhibited IL-1 and TNF but not g-CSF or IRAP production in human monocytes. At suboptimal concentrations of LPS (50 pg/ml), IL-6 and IL-8 production were also inhibited. Inhibition of cytokine biosynthesis was stimulus independent. For example, induction of IL-1 or TNF expression by phosphatase 1 and 2A inhibitors (Okadaic acid or Calyculin A) and Vitamin D3-dependent induction of IL-1 or TNF was also inhibited. In addition, IL-8 production, but not ICAM/E-Selectin expression in IL-l-stimulated HUVEC, was inhibited at similar ICsos. Taken together, the bicyclic imidazoles inhibit cytokine production selectively in a stimulus and cell type independent manner.

The effects of SK&F 86002 and other pyridinyl imidazole compounds on murine cytokine production were investigated. In vitro, SK&F 86002 inhibited LPS stimulated TNF-alpha production by the RAW 264.7 cell line and by oil elicited peritoneal macrophages with an IC50 of 5 microM. In general, the activity was reflective of previous results obtained with human monocytes as SK&F 86002 and its analogs demonstrated identical rank order potency for TNF-alpha inhibition in both species. These compounds also inhibited TNF-alpha in vivo in a murine model of endotoxin shock. Following oral administration, SK&F 86002 and its analogs reduced serum TNF-alpha levels by > 80% and afforded 100% protection from lethality. In contrast, tenidap, a novel anti-inflammatory drug, had minimal to no effect on murine TNF-alpha production in the same assays. These data further extend the pharmacological profile of the pyridinyl imidazoles by demonstrating that these compounds potently inhibit murine TNF-alpha production both in vitro and in vivo.

hibitory Potency. -A series of title compounds, e.g. (VII), is synthesized and tested for the ability to bind a recently discovered protein kinase termed CSBP ( CSAID binding protein) and to inhibit lipopolysaccharide-stimulated TNF production in mice. As one of the more potent inhibitors of TNF biosynthesis in mice, (VII) is inactive as an inhibitor of the enzymes 5-LO and PGHS-1 and decreases disease severity in the AA rat model of arthritis. The results suggest that the CSAID class of drugs may afford antiarthritic agents which treat the underlying disease process.-(BOEHM, J. C.; SMIETANA, J. M.; SORENSON, M. E.; GARIGIPATI, R. S.; GALLAGHER, T. F.; SHELDRAKE, P. L.; BRADBEER, J.; BADGER, A. M.; LAYDON, J. T.; LEE, J. C.; HILLEGASS, L. M.; GRISWOLD, D. E.; BRETON, J. J.; CHABOT-FLECHTER, M. C.; ADAMS, J. L.; J.