Induction of Nrf2-mediated genes by Antrodia salmonea inhibits ROS generation and inflammatory effects in lipopolysaccharide-stimulated RAW264.7 macrophages.

Antrodia salmonea (AS), a well-known medicinal mushroom in Taiwan, has been reported to exhibit anti-oxidant, anti-angiogenic, anti-atherogenic, and anti-inflammatory effects. In the present study, we investigated the activation of Nrf2-mediated antioxidant genes in RAW264.7 macrophages by the fermented culture broth of AS, studied the resulting protection against lipopolysaccharide (LPS)-stimulated inflammation, and revealed the molecular mechanisms underlying these protective effects. We found that non-cytotoxic concentrations of AS (25-100 μg mL⁻¹) protected macrophages from LPS-induced cell death and ROS generation in a dose-dependent manner. The antioxidant potential of AS was directly correlated with the increased expression of the antioxidant genes HO-1, NQO-1, and γ-GCLC, as well as the level of intracellular GSH followed by an increase in the nuclear translocation and transcriptional activation of the Nrf2-ARE pathway. Furthermore, Nrf2 knockdown diminished the protective effects of AS, as evidenced by the increased production of pro-inflammatory cytokines and chemokines, including PGE₂, NO, TNF-α, and IL-1β, in LPS-stimulated macrophages. Notably, AS treatment significantly inhibited LPS-induced ICAM-1 expression in macrophages. Our data suggest that the anti-inflammatory potential of Antrodia salmonea is mediated by the activation of Nrf2-dependent antioxidant defense mechanisms. Results support the traditional usage of this beneficial mushroom for the treatment of free radical-related diseases and inflammation.