Aralia cordata Extract Activates NF-κB and MAPK Signaling Pathways and Induces Pro-inflammatory Changes in RAW264.7 Macrophages

ABSTRACT

Macrophages play essential roles in innate immune responses by producing various immune mediators. Therefore, modulating macrophage function is an attractive strategy to treat immune disorders. Aralia cordata var. continentalis (AC), known as “Dokwhal” in Korea, possesses various biological and medicinal functions, including immunomodulation. The present study investigated the effect of the hot water extract of AC (HAC) on RAW264.7 murine macrophages. When these cells were treated with HAC, nitric oxide production and inducible nitric oxide synthase expression was induced dose-dependently. In addition, HAC treatment triggered the secretion of innate immune cytokines, such as TNF-α and IL-6. Phagocytosis, measured by FITC-dextran internalization showed that HAC stimulated the phagocytic activity of macrophages. Furthermore, HAC promoted the production of reactive oxygen species in RAW264.7 cells, determined by CM-H2DCFDA. In addition, the immunoblot analysis of intracellular signaling proteins revealed that NF-kB and MAPK signaling pathways, which are important signaling mediators of inflammation, are upregulated by HAC. In conclusion, these findings suggested that HAC can stimulate macrophage activity, and NF-kB and MAPK signaling pathways might be involved in the immunostimulatory effects of HAC.