Venezuelan equine encephalitis virus (VEEV) may cause encephalitis in humans, for which no FDA-approved antiviral treatment is available. Carbocyclic cytosine (carbodine) has broad-spectrum activity but toxicity has limited its utility. It was anticipated that one of the enantiomers of carbodine would show enhanced activity and reduced toxicity. The activity of the d-(-) enantiomer of carbodine [(-)-carbodine] was evaluated by infectious cell culture assay and was found to have a 50% effective concentration (EC50) of 0.2 microg/ml against the TC-83 vaccine strain of VEEV in Vero cells, while the l-(+) enantiomer had no activity. Virus titer inhibition correlated with intracellular cytidine triphosphate reduction after treatment with (-)-carbodine, as determined by HPLC analysis. Pre-treatment with 200 mg/(kgd) resulted in significant improvement in survival, virus load in the brain, weight change, and mean day-to-death in a mouse model of TC-83 VEEV disease. A single dose of (-)-carbodine resulted in a slight extension of mean time to death in mice infected with wild-type VEEV. Post-virus exposure treatment with (-)-carbodine was effective in significantly improving disease parameters in mice infected with TC-83 VEEV when treatment was initiated as late as 4 days post-virus installation (dpi). It is remarkable that (-)-carbodine is effective when initiated after the establishment of brain infection.

1997-01-01·Journal of immunology (Baltimore, Md. : 1950)

Regulation of tumor necrosis factor-alpha and IL-1 beta synthesis by thromboxane A2 in nonadherent human monocytes.

Article

作者: James, M J ; Caughey, G E ; Cleland, L G ; Pouliot, M

Synthesis of TNF-alpha and IL-1beta, by monocytes/macrophages can be partially regulated by the eicosanoid, PGE2. We report here that inhibition of both PGE2 and thromboxane A2 (TXA2) synthesis by a prostaglandin H synthase inhibitor, NS-398, had no effect on the synthesis of either TNF-alpha or IL-1beta, even though the addition of PGE2 to these treated cells dose-dependently inhibited TNF-alpha and IL-1beta synthesis. Because TXA2 is a major eicosanoid product of stimulated human monocytes, we examined its influence on cytokine production. Inhibition of thromboxane synthase by carboxyheptyl imidazole (CI) resulted in inhibition of TNF-alpha (61 +/- 4.3%; n = 8; p < 0.001) and IL-1beta (54 +/- 4.2%; n = 8; p < 0.001) synthesis by serum-treated zymosan-stimulated nonadherent human monocytes. This effect was observed when cytokine production was measured by ELISA or bioactivity assays. Furthermore, the addition of a TXA2 agonist, carbocyclic TXA2, to CI-treated monocytes dose-dependently restored the levels of TNF-alpha and IL-1beta synthesis to those found with serum-treated zymosan stimulation alone. Inhibition of TXA2 activity by the thromboxane receptor antagonists, pinane TXA2 or SQ 29,548, also inhibited the production of TNF-alpha (67 +/- 2.4% and 65 +/- 2.7%, respectively; n = 8; p < 0.001) and IL-1beta (59 +/- 3.3% and 70 +/- 1.2%, respectively; n = 8; p < 0.001). Treatment with CI resulted in a partial decrease in TNF-alpha mRNA levels (60 +/- 12.0%; n = 4), but had little or no effect on IL-1beta mRNA levels. These novel observations implicate TXA2 as an important paracrine or autocrine facilitator of TNF-alpha and IL-1beta production in stimulated human monocytes and suggest that levels of TNF-alpha and IL-1beta synthesis are determined in part by the balance between TXA2 and PGE2 production in human monocytes.

1995-06-01·The Journal of pharmacology and experimental therapeutics

Specific transcriptional inhibition of bone marrow-derived macrophage tumor necrosis factor-alpha gene expression and protein production using novel enantiomeric carbocyclic nucleoside analogues.

Article

作者: Bradshaw, M ; Edwards, C K ; Rutherford, M S ; McWhinney, C D ; Hoeper, B J ; Schook, L B ; Borcherding, D R

Tumor necrosis factor-alpha (TNF-alpha) is a powerful macrophage-derived proinflammatory cytokine, via both direct effects on host tissues as well as indirectly through the induction of other proinflammatory mediators, including interleukin- (IL) 1 beta and IL-6. Activation of murine bone marrow-derived macrophages (BMDM phi) with lipopolysaccharide (LPS) causes rapid expression of TNF-alpha, which as an autocrine factor enhances BMDM phi function through IL-1 beta and IL-6 production. In this study, we have examined the specific transcriptional inhibition of BMDM phi TNF-alpha using novel enantiomeric carbocyclic nucleoside analogues. BMDM phi were derived in vitro from murine bone marrow progenitors using colony stimulating factor-1 and treated with combinations of LPS (1-100 nG/ml) and the enantiomeric carbocyclic nucleoside (10-100 microM) analogues MDL 201, 112 (9-[(1S,3R)-cis-cyclopentan-3-ol]adenine); MDL 201,451 (9-[1R,3S)-cis-cyclopentan-3-ol]adenine); MDL 201,449 (9-[(1R,3R)-trans-cyclopentan-3-ol]adenine) and MDL 201,484 (9-[(1S,3S)-trans-cyclopentan-3-ol]adenine). Northern blot analysis showed that MDL 201,449 was the most effective agent in vitro at selectively inhibiting TNF-alpha. MDL 201,449 reduced TNF-alpha mRNA levels by nearly 50% for up to 4 hr after the simultaneous addition of LPS and the synthetic agent. In contrast, mRNA and secreted protein levels for IL-1 beta (measured by the D10.S bioassay) and mRNA for TNF-alpha receptor p60 and TNF-alpha receptor p80 were not significantly affected. Carbocyclic nucleoside analogues were effective when added to BMDM phi up-to 2 hr after LPS treatment and at concentrations as low as 10 microM. Regulation of BMDM phi IL-6 by carbocyclic nucleoside analogues in response to LPS appears to be both concentration and time dependent, because IL-6 mRNA and secreted protein levels were inhibited at only high drug concentrations (100 microM) and effective only at longer exposure times (+4 hr of incubation) to LPS. These data support the concept that M phi-derived proinflammatory cytokine gene expression is differentially, rather than coordinately, regulated by selective signal transduction and/or molecular pathways. Enantiomeric carbocyclic nucleoside analogues that specifically inhibit TNF-alpha may have therapeutic potential in inflammatory diseases, such as systemic inflammatory response syndrome, where TNF-alpha has been shown to have an important role in initiating the early stages of disease.

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