title: Suppression of tumor necrosis factor-alpha production by interleukin-10 is enhanced by cAMP-elevating agents.
abstract: The pro-inflammatory peptide tumor necrosis factor-alpha (TNF) stimulates production of the anti-inflammatory cytokine-interleukin-10 by monocytes which in turn inhibits the synthesis of TNF. This inhibitory effect of interleukin-10 may contribute to the balance of pro- and anti-inflammatory cytokines in several diseases, e.g., chronic inflammatory bowel disease. In the present study we addressed the question whether interleukin-10 in combination with other TNF-suppressing agents leads to enhanced suppression of TNF synthesis. We investigated the inhibitory potency of interleukin-10 in combination with rolipram, a specific type IV phosphodiesterase inhibitor, or with cicaprost, a stable prostacyclin analogue in lipopolysaccharide-stimulated human peripheral blood mononuclear cells. Peripheral blood mononuclear cells were stimulated with 10 ng/ml lipopolysaccharide in the absence or presence of interleukin-10 or one of the cAMP-elevating agents. First, we confirmed the TNF-suppressing effect of interleukin-10, rolipram and cicaprost alone and determined the IC50 for these substances. Second, for the combination of interleukin-10 with one of the cAMP-elevating substances we were able to demonstrate enhanced TNF inhibition. Of these, the combination of interleukin-10 and rolipram revealed an additive effect. The maximal TNF synthesis of 5.5 +/- 1.1 ng/ml after lipopolysaccharide stimulation alone was inhibited by 0.1 ng/ml interleukin-10 to 2.7 +/- 0.6 ng/ml TNF and by 100 nM rolipram to 3.1 +/- 0.6 ng/ml TNF. Both substances combined suppressed TNF synthesis to 1.5 +/- 0.3 ng/ml. After stimulation with Staphylococcus epidermidis we could demonstrate a more pronounced inhibition of TNF synthesis by interleukin-10 compared to rolipram which was more effective after stimulation with lipopolysaccharide. Finally, the additive inhibitory effect of interleukin-10 and rolipram could be confirmed on the level of TNF mRNA. The results obtained in the present investigation could form a prerequisite to study the combination of interleukin-10 and cAMP-elevating agents in in vivo models of acute or chronic inflammatory diseases.
authors.affiliation: Medizinische Klinik, Ludwig Maximilians-University, Munich, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Siegmund
authors.forename: A
authors.initials: A
authors.lastname: Eigler
authors.forename: J
authors.initials: J
authors.lastname: Moeller
authors.forename: T F
authors.initials: TF
authors.lastname: Greten
authors.forename: G
authors.initials: G
authors.lastname: Hartmann
authors.forename: S
authors.initials: S
authors.lastname: Endres
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D015152:Blotting, Northern; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis* / Q000097:blood; D004357:Drug Synergism; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D016753:Interleukin-10 / Q000493:pharmacokinetics / Q000494:pharmacology*; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000493:pharmacokinetics / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020889:Rolipram; D013212:Staphylococcus epidermidis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D000970:Antineoplastic Agents; D008070:Lipopolysaccharides; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D011464:Epoprostenol; D000242:Cyclic AMP; D020889:Rolipram; C043867:cicaprost