Contribution of FP receptors in M1 macrophage polarization via IL-10-regulated nuclear translocation of NF-κB p65.

Macrophages are the effector immune cells with plasticity to differentiate as M1 (classically activated) and M2 (alternatively activated) phenotypes. Prostaglandins (PGs) have various important roles and are involved in the regulation of macrophage activation. However, the role of PGF in macrophage activation remains unclear. We investigated the role of PGF receptor (FP)-mediated signaling in the M1 macrophage polarization using murine macrophage RAW264.7 cells. Stimulation with lipopolysaccharide (LPS) + interferon (IFN)-γ increased the mRNA expression of the M1 macrophage markers such as inducible nitric oxide synthase, tumor necrosis factor-α, and CD11c. Pre-treatment with AL8810, an FP receptor antagonist, further enhanced the expression of these genes. In contrast, treatment with fluprostenol, an FP receptor agonist, decreased the LPS + IFN-γ-induced expression of M1 markers. LPS-induced M1 macrophage polarization was dependent on the activation of NF-κB p65. Treatment with IκB kinase β inhibitor reduced AL8810-induced mRNA expression of the M1 markers. Stimulation with LPS + IFN-γ increased the expression of IL-10. Pre-treatment with AL8810 lowered LPS + IFN-γ-induced IL-10 expression, and further enhanced LPS + IFN-γ-stimulated nuclear translocation of NF-κB p65. In contrast, co-treatment with IL-10 reversed AL8810-induced nuclear translocation of NF-κB p65. These results indicate that the FP receptor signaling was involved in the control of M1 polarization of macrophages via IL-10-regulated nuclear translocation of NF-κB p65.