The biphasic immunoregulation of pyrimidylpiperazine (Y-40138) is IL-10 sensitive and requires NF-kappa B targeting in the alveolar epithelium

1 Pyrimidylpiperazine (Y-40138), a synthetic derivative of N-[1-(4-{[4-(pyr imidin-2-yl)piperazin-1-yl]methyl}phenyl)cyclopropyl] acetamide, is a novel dual regulator of pro- and anti-inflammatory cytokines in vivo. The aim of the present study was to determine the signal transduction mechanisms impl icated in vitro. 2 In alveolar epithelial cells, pre-treatment (30 min) with Y-40138 reduced LPS-induced biosynthesis of IL-1 beta, IL-6 and TNF-alpha, an effect paral leled by up-regulating an anti-inflammatory counter-loop mediated through I L-10. 3 This differential regulation of pro- and anti-inflammatory signals was ac companied by an inhibition of the nuclear localization of selective NF-kapp aB subunits, particularly NF-kappaB(1) (p50), RelA (p65), the major transac tivating member of the Rel family, RelB (p68) and c-Rel (p75). In addition, Y-40138 blockaded, in a dose-dependent manner, the LPS-induced nuclear act ivation of NF-kappaB. 4 Analysis of the upstream pathway involved in Y-40138-dependent retardatio n of LPS-induced NF-kappaB translocation/activation revealed the involvemen t of an I kappaB-alpha sensitive pathway. Pre treatment with Y-40138 amelio rated LPS-induced degradation of I kappaB-alpha in the cytosolic compartmen t and retarded its phosphorylation, suggesting the involvement of an upstre am kinase. 5 Recombinant IL-10 (0-10 ng ml(-1)) blockaded, in a dose-dependent manner, LPS-induced biosynthesis of IL-1 beta, IL-6 and TNF-alpha. Furthermore, rh IL-10 reduced the DNA binding activity of NF-kappaB. Immunoneutralization o f endogenous IL-10 by a polyclonal alpha IL-10 (5 mug ml(-1)) reversed the inhibitory effect of Y-40138 on pro-inflammatory cytokines and partially re stored the DNA binding activity of NF-kappaB. 6 These results indicate that Y-40138 mediated dual immunoregulation of pro - and antiinflammatory cytokines is IL-10 sensitive and mediated through th e I kappa -B-alpha /NF-kappaB signal transduction pathway.