Fig. 2

The major signaling pathways activated in response to oxidative stress and its relation with inflammation. Reactive oxygen species (ROS) originating from environmental signals or from metabolic activity are modulated by antioxidants to non-toxic levels, at which point they serve as signaling molecules that can trigger pro-inflammatory gene expression leading to a state of chronic inflammation. ROS can activate gene transcription-related to inflammation in two ways: (a) via transcription factors, such as NF-κB, AP-1, and ARE-binding proteins (ARE-BP) that can interact directly with specific DNA motifs on promoters of target genes, or (b) via activation of MAPK cascades, which in turn activate transcription factors that trigger target gene transcription. The degree to which a given pathway is activated depends on the nature and duration of the stress, as well as on cell type and developmental stage. NF-κB = nuclear factor-kappa B; AP-1 = activator protein-1; HIF-1 = Hypoxia Inducible factor 1