Establishment of reporter platforms capable of detecting NF-κB mediated immuno-modulatory activity.

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are transcriptional targets of nuclear factor kappa B (NF-κB) that are involved in inflammatory responses. The aim of this study is to develop a method for efficiently detecting inflammation modulatory activities. Here we established RAW264.7 macrophage cells stably expressing a luciferase reporter gene directed by iNOS or COX-2 promoter. Lipopolysaccharide (LPS) treatment stimulated the luciferase activity which paralleled with increased iNOS and COX-2 mRNA levels determined by RT-q-PCR. The LPS-stimulated luciferase activity was blocked by NF-κB inhibitor CAPE and by nobiletin, an anti-inflammatory natural product from citrus peels. We have applied the platforms to screen various mushroom species; analysis by scatter plot revealed a strong correlation to the results obtained by ELISA-based detection of TNF-α. Together we have established luciferase reporter systems sensitive to NF-κB-dependent iNOS and COX-2 activation, which provides an alternative screening method for identifying food components with immune-modulatory activities.