Immunomodulatory Activities of Body Wall Fatty Acids Extracted from <i>Halocynthia aurantium</i> on RAW264.7 Cells

Abstract

Tunicates are known to contain biologically active materials and one species in particular, the sea peach (<i>Halocynthia aurantium</i>), has not been thoroughly studied. In this study we aimed to analyze the fatty acids profile of the <i>H. aurantium</i> body wall and its immunomodulatory effects on RAW264.7 macrophage-like cells. The fatty acids were classified into three categories: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). Omega-3 fatty acid content, including EPA and DHA, was higher than omega-6 fatty acids. <i>H. aurantium</i> body wall fatty acids exhibited enhanced immune response and anti-inflammatory effects on RAW264.7 macrophage-like cells. Under normal conditions, fatty acids significantly increase nitric oxide (NO) and PGE₂ production in a dose-dependent manner, thereby improving the immune response. On the other hand, in LPS-treated RAW264.7 cells, fatty acids significantly decreased nitric oxide (NO) and PGE2 production in a dose-dependent manner, thereby enhancing anti-inflammatory effects. Fatty acids transcriptionally control the expression of the immune-associated genes, <i>iNOS, IL-1β, IL-6, COX-2</i>, and <i>TNF-α</i>, via the MAPK and NF-κB signaling cascades in RAW264.7 cells. However, in LPSstimulated RAW264.7 cells, H. aurantium body wall fatty acids significantly inhibited expression of inflammatory cytokine; similarly, production of COX-2 and PGE₂ was inhibited. The results of our present study provide insight into the immune-improving and anti-inflammatory effects of <i>H. aurantium</i> body wall fatty acids on macrophages. In addition, our study demonstrates that <i>H. aurantium</i> body wall is a potential source of immune regulatory components.