E5564 (Eritoran) inhibits lipopolysaccharide-induced cytokine production in human blood monocytes.

OBJECTIVE AND DESIGN: In this ex vivo laboratory study, we investigated the effects of E5564 (eritoran), a toll-like receptor 4-directed endotoxin antagonist, on intracellular expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in lipopolysaccharide (LPS)-stimulated human monocytes assessed by flow cytometry. MATERIAL AND METHOD: Whole blood samples from 10 healthy volunteers (average age: 32 +/- 2 years) were pre-incubated with 0.001, 0.003, 0.01, 0.03, 0.1, 0.3, 1 and 10 ng/ml E5564 for 45 min and after this stimulated with LPS (0.2 ng/ml), a dose we found to be the most effective for stimulation. Samples were incubated for 3 h at 37 degrees C and 5% CO(2). Intracellular expression of IL-6 and TNF-alpha was assessed by flow cytometry. RESULTS: Our investigation showed that E5564 (0.03 ng/ml up to 10 ng/ml) caused a dose-dependent inhibitory effect on IL-6 and TNF-alpha production in LPS-stimulated human monocytes. CONCLUSIONS: The results of this investigation led us to conclude that E5564 has a remarkable LPS inhibitory activity manifested via down-regulation of the intracellular generation of pro-inflammatory cytokines IL-6 and TNF-alpha in human monocytes.

[Expression und function of the ORL-1 receptor on human leukocytes]. / Expression und Funktion des ORL-1-Rezeptors auf humanen Leukozyten.

BACKGROUND: The ORL-1 receptor is expressed by human leukocytes. Limited knowledge exists about the function and interaction between the nervous and immune systems. The aim of our study was to investigate the expression of the nociceptin-ORL-1 receptor system on different leukocyte subsets and the influence of the ORL-1 receptor on the intracellular production of cytokines. METHODS: Blood from healthy volunteers of different age and sex was analysed for the expression of the ORL-1 receptor by PCR and flow cytometry and the influence of nociceptin on the LPS-induced production of intracellular cytokines by flow cytometry. RESULTS: The ORL-1 receptor mRNA is expressed by granulocytes, lymphocytes and monocytes. We could also show the expression of the ORL-1 receptor protein on the cell surface of all types of white blood cells. Nociceptin has no influence on LPS-induced cytokine production in human monocytes. There was neither a difference between young and old nor between male or female volunteers. CONCLUSION: The ORL-1 receptor is expressed by all subtypes of leukocytes. The function of this receptor is not the modulation of cytokine production and requires further studies.