Recently, as a natural substance has been emphasized interest in research to enhance the immune function. Green lettuce (Lactuca sativa L.) is a popular vegetable used fresh and it contains various phytochemicals and antioxidant compounds, and has been reported to have various physiological activities such as antibacterial, antioxidant, antitumor and anti-mutagenic. However, only a few studies have investigated on the mechanism of action of immune-enhancing activity of lettuce. Therefore, in this study, the immunomodulatory activities and potential mechanism of action of Green lettuce extracts (GLE) were evaluated in the murine macrophage cell line RAW264.7. GLE significantly increased NO levels by RAW264.7 cells, as well as expressions of immunomodulators such as iNOS, COX-2, IL-1β, IL-6, IL-12, TNF-α and MCP-1. Although GLE activated ERK1/2, p38, JNK and NF-κB, GLE-mediated expressions of immunomodulators was dependent on p38, JNK and NF-κB. In addition, TLR4 inhibition blocked GLE-mediated expressions of immunomodulators and activation of p38, JNK and NF-κB. Taken together, these results demonstrated that TLR4-MAPK/NF-κB signalling pathways participated in GLE-induced macrophage activation and GLE could be developed as a potential immunomodulating functional food.

Abstract
Introduction
Materials and Methods
    Reagents
    Sample preparation
    Cell culture and treatment
    Cell viability assay
    Measurement of NO production
    Isolation of cytosol and nucleus fraction
    SDS-PAGE and Western blot analysis
    Reverse transcriptase-polymerase chain reaction (RT-PCR)
    Statistical analysis
Results and Discussion
    Effect of GLE on the activation of RAW264.7 cells
    Effect of GLE on MAPK/NF-κB signaling pathwayactivation in RAW264.7 cells
    Contribution of p38, JNK and NF-κB to GLE-mediatedexpression of immunomodulators in RAW264.7 cells
    Effect of TLR4 on GLE-mediated expression of immunomodulatorsthrough the activation of p38, JNK and NF-κB
References

• Hyun-Ju Seo(Institute of Agricultural Science and Technology, Andong National University)
• Jin Boo Jeong(Department of Medicinal Plant Resources, Andong National University) Corresponding author