NOX2 in autoimmunity, tumor growth and metastasis

Myeloid cell NADPH oxidase isoform 2 (NOX2) generates reactive oxygen species (ROS) that participate in defense against microbial pathogens. Humans with compromised NOX2‐mediated ROS formation develop chronic granulomatous disease characterized by recurrent bacterial and fungal infections. Additionally, impaired NOX2 function entails hyperactive lymphocytes and autoimmunity in humans and in murine models. The impact of NOX2 and ROS on cancer development is only partly explored. Recent research published in the Journal of Pathology showed that genetic depletion of any of the NOX2 subunits Cyba, Cybb, Ncf1, Ncf2 and Ncf4 reduced the formation of lung metastases following intravenous injection of murine tumor cells. These findings, together with the role of NOX2 in maintaining self‐tolerance, imply that NOX2 is a targetable immune checkpoint in cancer. In particular, the possibility of modulating NOX2 to improve lymphocyte‐mediated control of metastatic cells merits further investigation. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.