Immune modulatory properties of 6-gingerol and resveratrol in Atlantic salmon macrophages

The innate immune system provides the first barrier to infection and disease through various processes including activation of inflammation. Inflammation is a biological process whereby immune cells, including macrophages, respond to, and work together to eliminate, damage from injury and disease. Chronic or sustained inflammation, however, can be detrimental to the health and growth of animals, including fish. Immune modulating functional plant compounds, supplemented as feed additives, may be safe and natural approaches to controlling inflammation and disease. This project employed an in vitro cell model to assess the effect of two plant phytoextracts, 6-gingerol and resveratrol, on Atlantic salmon macrophages. To determine if these plant compounds can modify Atlantic salmon macrophage function, primary macrophages were isolated from the head kidney, cultured and pre-treated with the compound for 24 hours. The cells were then challenged with a bacterial pathogen-associated molecular pattern (PAMP), lipopolysaccharide (LPS). To determine if the plant compound pre-treatment modifies macrophage response to LPS stimulation, the mRNA expression of anti-bacterial and cytokine genes (COX2, TNFα, IL-1β, IL-8, Lect-2 and sTLR5) was analyzed by real-time quantitative polymerase chain reaction (qPCR). In addition, the effects of compound pre-treatment on macrophage ROS production and phagocytic responses were analyzed via flow cytometry. We found that both 6-gingerol and resveratrol modified macrophage function, with 6-gingerol having an overall greater effect on expression of the genes analyzed, suggesting that these functional plant compounds may be good candidates as feed additives and should be investigated further.