Pro-inflammatory mediators, such as nitric oxide (NO), prostaglandin E-2 (PGE(2)), and several cytokines (tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6) are responsible for central nervous system (CNS) injuries that include ischemia, Alzheimer's disease, and neural death. Inhibition of these pro-inflammatory mediators would be an effective therapy to reduce the progression of neurodegenerative diseases. In this study, we examined the anti-inflammatory effects of a human prothrombin fragment-2-derived peptide, NSA9 (NSAVQLVEN), on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-activated brain microglia. NSA9 significantly inhibited the release of NO, PGE(2), and pro-inflammatory cytokines in a dose-dependent manner. Furthermore, NSA9 reduced the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 mRNA and protein, which control the production of NO and PGE2, respectively. Moreover, NSA9 suppressed the LPS-induced nuclear translocation and activation of nuclear factor-kappa B (NF-kappa B). These results suggest that NSA9 strongly inhibits the pro-inflammatory responses of microglia through the modulation of NF-kappa B activity. (c) 2008 Elsevier Inc. All rights reserved.