Regulation of virus-induced inflammatory response by Dunaliella salina alga extract in macrophages

Previous reports have suggested that many constituents within various algal samples are able to attenuate LPS-induced inflammatory effects. To date no report has been published on the regulation of virus-induced inflammatory response of Dunaliella salina carotenoid extract. In the present study, the anti-inflammatory effect of D. salina carotenoid extract on pseudorabies virus (PRV)-infected RAW 264.7 macrophages was investigated.We evaluated the anti-inflammatory effect of D. salina carotenoid extract on PRV-infected RAW 264.7 cells by measuring cell viability, cytotoxicity, production of inflammatory mediators such as NO, iNOS, COX-2, pro-inflammatory cytokines and anti-virus replication by plaque assay.We found down-regulation of the expression of the iNOS, COX-2 and pro-inflammatory genes IL-1β, IL-6, TNF-α, and MCP-1 in a dose-dependent manner. Although there was no effect on viral replication, there were tendencies toward lower virus titer and tendencies toward higher cell survival. Most importantly, we found that inhibition of TLR9, PI3K and Akt phosphorylation plays a crucial role in the extract-mediated NF-κB regulation by modulating IKK-IκB signaling in PRV-infected RAW264.7 cells. These results indicate that D. salina carotenoid extracts inhibited inflammation by inhibition of NF-κB activation by TLR9 dependent via PI3K/Akt inactivation.