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

Figure 6

MyD88 is required for synergistic IL-10 expression by LPS and cAMP. (a) RAW264.7 macrophages were transfected with a full mouse IL-10 promoter reporter construct. The cells were treated for 3 h with a combination of isoproterenol (Iso, 1 μM) and the PDE4 inhibitor rolipram (20 μM), in the presence or absence of a TLR agonist, either LPS (10 ng/ml; TLR4), Pam2Cys (0.1 ng/ml; TLR2/6), poly(I:C) (50 μg/ml; TLR3), or imiquimod (50 μM; TLR7). Luciferase reporter data expressed as the () of values normalized against Renilla luciferase activity. compared to control cells stimulated with isoproterenol+rolipram. Reporter activity following administration of any TLR agonist alone (without the cAMP inducers) was indistinguishable from control values. (b) BMDM from WT (C57BL/6) and corresponding MyD88 knockout mice were incubated for 3 h with LPS (10 ng/ml) and/or isoproterenol (Iso, 1 μM). The medium was collected, and secretion of endogenous IL-10 was measured by ELISA. Data represent the (). compared to WT. The experiments were carried out five (a) or three times (b) with similar results.

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