The NADPH Oxidase Nox4 Controls Macrophage Polarization in an NF?B-Dependent Manner.

ABSTRACT: The family of NADPH oxidases represents an important source of reactive oxygen species (ROS) within the cell. Nox4 is a special member of this family as it constitutively produces H₂O₂ and its loss promotes inflammation. A major cellular component of inflammation is the macrophage population, which can be divided into several subpopulations depending on their phenotype, with proinflammatory M(LPS+IFN?) and wound-healing M(IL4+IL13) macrophages being extremes of the functional spectrum. Whether Nox4 is expressed in macrophages is discussed controversially. Here, we show that macrophages besides a high level of Nox2 indeed express Nox4. As Nox4 contributes to differentiation of many cells, we hypothesize that Nox4 plays a role in determining the polarization and the phenotype of macrophages. In bone marrow-derived monocytes, ex vivo treatment with LPS/IFN? or IL4/IL13 results in polarization of the cells into M(LPS+IFN?) or M(IL4+IL13) macrophages, respectively. In this ex vivo setting, Nox4 deficiency reduces M(IL4+IL13) polarization and forces M(LPS+IFN?). Nox4-/- M(LPS+IFN?)-polarized macrophages express more Nox2 and produce more superoxide anions than wild type M(LPS+IFN?)-polarized macrophages. Mechanistically, Nox4 deficiency reduces STAT6 activation and promotes NF?B activity, with the latter being responsible for the higher level of Nox2 in Nox4-deficient M(LPS+IFN?)-polarized macrophages. According to those findings, in vivo, in a murine inflammation-driven fibrosarcoma model, Nox4 deficiency forces the expression of proinflammatory genes and cytokines, accompanied by an increase in the number of proinflammatory Ly6C⁺ macrophages in the tumors. Collectively, the data obtained in this study suggest an anti-inflammatory role for Nox4 in macrophages. Nox4 deficiency results in less M(IL4+IL13) polarization and suppression of NF?B activity in monocytes.

SUBMITTER: Helfinger V 

PROVIDER: S-EPMC6501210 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature