Polyunsaturated fatty acids (PUFAs) are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism.

Tunicates are known to contain biologically active materials and one species in particular, the sea peach ( Halocynthia aurantium ), has not been thoroughly studied. In this study we aimed to analyze the fatty acids profile of the H. aurantium 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. H. aurantium 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 PGE 2 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 PGE 2 production in a dose-dependent manner, thereby enhancing anti-inflammatory effects. Fatty acids transcriptionally control the expression of the immune-associated genes, iNOS, IL-1β, IL-6, COX-2 , and TNF-α , 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 PGE 2 was inhibited. The results of our present study provide insight into the immune-improving and anti-inflammatory effects of H. aurantium body wall fatty acids on macrophages. In addition, our study demonstrates that H. aurantium body wall is a potential source of immune regulatory components.

Asterias amurensis (starfish) is a marine organism that is harmful to the fishing industry, but is also a potential source of functional materials. The present study was conducted to analyze the profiles of fatty acids extracted from A. amurensis tissues and their anti-inflammatory effects on RAW264.7 macrophage cells. In different tissues, the component ratios of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids differed; particularly, polyunsaturated fatty acids such as dihomo-gamma-linolenic acid (20:3n-6) and eicosapentaenoic acid (20:5n-3) were considerably different. In lipopolysaccharide-stimulated RAW264.7 cells, fatty acids from A. amurensis skin, gonads, and digestive glands exhibited anti-inflammatory activities by reducing nitric oxide production and inducing nitric oxide synthase gene expression. Asterias amurensis fatty acids effectively suppressed the expression of inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and interleukin-6 in lipopolysaccharide-stimulated cells. Cyclooxygenase-2 and prostaglandin E 2 , which are critical inflammation biomarkers, were also significantly suppressed. Furthermore, A. amurensis fatty acids reduced the phosphorylation of nuclear factor-κB p-65, p38, extracellular signal-related kinase 1/2, and c-Jun N-terminal kinase, indicating that these fatty acids ameliorated inflammation through the nuclear factor-κB and mitogen-activated protein kinase pathways. These results provide insight into the anti-inflammatory mechanism of A. amurensis fatty acids on immune cells and suggest that the species is a potential source of anti-inflammatory molecules.