Reactive Oxygen Species Regulate Both Priming and Established Arthritis, but with Different Mechanisms.

Neutrophil cytosolic factor 1 (NCF1) is a key regulatory component of the phagocytic NOX2 complex, which produces reactive oxygen species (ROS). Polymorphism of the Ncf1 gene is associated with increased arthritis severity. In this study, we generated targeted Ncf1 knock-in mice with inducible Ncf1 expression and determined the critical time window during which the NOX2-derived ROS protect the mice from arthritis. Targeted Ncf1 knock-in mice lacked NOX2-derived ROS, and in vivo allelic conversion of Ncf1 by the CreER