The cAMP Pathway Amplifies Early MyD88-Dependent and Type I Interferon-Independent LPS-Induced Interleukin-10 Expression in Mouse Macrophages

Figure 5

Isoproterenol synergistically amplifies only direct LPS-induced IL-10 transcription at the early phase, but not late, type I IFN-dependent LPS activity. (a, b) RAW264.7 macrophages were transfected with a full mouse IL-10 promoter reporter construct. (a) Left panel: nontransfected RAW264.7 macrophages were incubated for 21 h with either LPS (10 ng/ml) or vehicle, and the conditioned medium (CM) was collected. Then, the IL-10 promoter reporter cells were incubated for 3 h with either CM from LPS-treated cells in the presence or absence of isoproterenol (Iso, 1 μM) or with CM from vehicle-treated cells together with isoproterenol. The LPS antagonist polymyxin B (50 μM) was added to the CM in all treatments. Right panel: synergism between isoproterenol and LPS (10 ng/ml) is shown for comparison. (b) The IL-10 promoter reporter cells were incubated for 8 h with isoproterenol (Iso, 1 μM) and/or either mouse IFNα (2000 units/ml, left panel) or LPS (10 ng/ml, right panel). (a, b) Luciferase reporter data expressed as the () of values normalized against Renilla luciferase activity, relative to unstimulated control cells. , for cells monostimulated relative to cells costimulated. The experiments were carried out twice with similar results.

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