NOS2 and osteoarthritis: Ok-PDRN decreased reactive oxygen species levels and expression of inflammatory mediators and cytokines [cyclooxygenase-2 (COX-2), IL-1β, inducible NO synthase, and TNF-α] on a human chondrocyte cell line treated with 2 mM H2O2, suggesting the potential applicability of Ok-PDRN as an osteoarthritis (OA) treatment [21].