Expression of key immune genes in polarized porcine monocyte-derived macrophage subsets

Swine are considered one of the most relevant large animal biomedical models since they share many immunological similarities with humans. Despite that, macrophage polarization has not comprehensively investigated in pigs. In this study, porcine monocyte-derived macrophages (moMΦ) were untreated or stimulated with IFN-γ + LPS (classical activation), or by different M2 polarizing stimuli: IL-4, IL-10, TGF-β, or dexamethasone. Expression of key cytokine genes (IL1B2, IL33, IL19, IL22, IL26, CCL17, CCL24, IFNA, IFNB) in macrophage subsets were investigated over time. Expression of the genes encoding the two main enzymes of the arginine pathway (ARG1, NOS2), and molecules related to alternative macrophage polarization in human and mice (MMP9, MRC1, FIZZ1, VEGFA) were also assessed. Stimulation with IFN-γ + LPS triggered up-regulation of IL1B2, IFNB, NOS2, whereas IL-4 triggered upregulation of CCL17, CCL24, CXCR2, and ARG1 expression. IL19 and IL22 expression was enhanced by stimulation with IFN-γ + LPS or TGF-β, but not IL-4, IL-10, or dexamethasone. Our data highlighted some peculiarities in swine, such as induced expression of IL33 after stimulation with IFN-γ + LPS, and no up-regulation of FIZZ1, VEGFA or MMP9 after exposure to any of the M2 polarizing stimuli. A better understanding of porcine macrophage polarization could benefit translational studies using this large animal model.