title: Divergent effects of LPS on expression of IL-1 receptor family members in mononuclear phagocytes in vitro and in vivo.
abstract: Three molecules, interleukin 1 (IL-1) receptor I (IL-1RI), IL-1 receptor II (IL-1RII or decoy) and IL-1 receptor accessory protein (IL-1R AcP or IL-1RIII), are involved in IL-1 binding and signal transduction. In addition, three homologous genes (T1/ST2, MyD88 and rsc786) have been identified. Expression of the signal transducing type I R and of the decoy type II R in human monocytes is regulated by pro- and anti-inflammatory signals. The present study was designed to evaluate comprehensively how a prototypic pro-inflammatory signal, bacterial lipopolysaccharide (LPS), affects expression of IL-1R family members in mononuclear phagocytes in vitro and in vivo. Resting human monocytes expressed high levels of IL-1RII, IL-1R AcP, MyD88 and rsc786, whereas low levels of IL-1RI and T1/ST2 were present. In vitro exposure to LPS augmented expression of IL-1RI, T1/ST2 and MyD88, whereas it inhibited that of IL-1RII and rsc786. Expression of IL-1R AcP in monocytes was less substantially affected by LPS. The expression of IL-1R family members was also studied in organs of mice given LPS. As expected on the basis of in vitro results, organs (e.g. spleen, lungs and peritoneal exudate cells) from LPS-treated mice showed increased levels of IL-1RI, T1/ST2 and MyD88. Intriguingly, while expression of IL-1RII was inhibited in peritoneal macrophages after LPS, in accordance with in vitro results, increased IL-1RII mRNA was observed in organs such as liver, lungs and spleen. This unexpected effect of LPS was drastically reduced in mice rendered neutropenic by 5-fluorouracil. Therefore, we conclude that the apparent induction of IL-1RII in certain organs of LPS-treated mice is due to recruitment of myeloid cells which express high levels of decoy RII. Therefore, members of IL-1R family are independently and divergently regulated in mononuclear phagocytes exposed to the prototypic pro-inflammatory signal LPS in vitro and in vivo.
authors.affiliation: Department of Immunology and Cell Biology, Istituto di Ricerche Farmacologiche "Mario Negri", Centro Daniela e Catullo Borgomainerio, 20157 Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Saccani
authors.forename: N
authors.initials: N
authors.lastname: Polentarutti
authors.forename: G
authors.initials: G
authors.lastname: Penton-Rol
authors.forename: J E
authors.initials: JE
authors.lastname: Sims
authors.forename: A
authors.initials: A
authors.lastname: Mantovani
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D006801:Humans; D000072179:Interleukin-1 Receptor-Like 1 Protein; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D053594:Myeloid Differentiation Factor 88; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D018123:Receptors, Interleukin; D017472:Receptors, Interleukin-1 / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; C079241:IL1RL1 protein, human; C486189:Il1rl1 protein, mouse; D000072179:Interleukin-1 Receptor-Like 1 Protein; D008070:Lipopolysaccharides; C507779:MYD88 protein, human; D008565:Membrane Proteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D018123:Receptors, Interleukin; D017472:Receptors, Interleukin-1; D003609:Dactinomycin; D003513:Cycloheximide