Pharmaceutical Regulation of Intracellular Redox Balance Prevents Macrophages Polarization to Pro-Inflammatory Phenotype

The balance between production and neutralization of reactive oxygen species (ROS) regulates macrophage polarization, which determines the progression and resolution of inflammation. Nonetheless, the redox profiles of pro-inflammatory (M1) and anti-inflammatory (M2) macrophages remain controversial, and it is not clear if modulation of ROS production can reprogram macrophage phenotype. Using THP-1-derived macrophages polarized with IFN-γ/LPS (M1) or IL-4/IL-13 (M2), we characterized ROS production in different cellular compartments, NADPH oxidase activity, antioxidant capacity, nitric oxide (NO) production and lipid peroxidation. We found that M2 macrophages had higher rates of cytosolic and mitochondrial ROS production and higher reduced glutathione (GSH) content. While cytosolic ROS predominance on M2 macrophages is mostly linked to basal level of NADPH oxidases activity, M1 macrophages had a stronger PMA-inducible ROS production. Despite the lower oxidation of ROS-sensitive probes, M1 macrophages demonstrated increased NO production and lipid peroxidation, indicating higher possibility of oxidative and nitrosative stress. Incubation of the cells with IFN-γ/LPS-induced polarization with sodium aminodihydrophthalazinedione (ADPh) increased superoxide production and decreased NO levels without changing GSH content. Subsequently, ADPh reduced the proportion of CD80-positive cells and GLUT1-dependent glucose uptake, indciating the shift of macrophages polarization towards an M2-like phenotype even in the presence of IFN-γ/LPS. Thus, stimulation of ROS production, rather than only activation of antioxidant systems, can prevent pro-inflammatory macrophage polarization.