Thioredoxin activity confers resistance against oxidative stress in tumor-infiltrating NK cells.

To improve the clinical outcome of adoptive NK cell therapy in patients with solid tumors, NK cells need to persist within the tumor microenvironment (TME) in which the abundance of reactive oxygen species (ROS) could dampen anti-tumor immune responses. In the present study, we demonstrated that IL-15 primed NK cells acquire resistance against oxidative stress through thioredoxin system activated by mTOR. Mechanistically, the activation of thioredoxin showed dependence on localization of thioredoxin-interacting protein. For the first time, we showed that NK cells residing in the tumor core expressed higher thiol density which could aid to protect other lymphocytes against ROS within the TME. Furthermore, the prognostic value of IL15 and NK cell gene signature in tumors may be influenced by tobacco smoking history in NSCLC patients. Collectively, the levels of reducing antioxidants in NK cells may not only predict for better tumor penetrance but even potentially response to immune therapy.