Inhibitory Effects and Molecular Mechanism of an Anti-inflammatory Peptide Isolated from Intestine of Abalone, Haliotis D iscus H annai on LPS-Induced Cytokine Production via the p-p38/p-JNK Pathways in RAW264.7 Macrophages

Abstract

A marine mollusk, abalone (Haliotis discus hannai) is one of the important species in aquaculture industry, but nutraceutical and pharmaceutical benefits of H. discus hannai have been rarely identified and studied. To evaluate beneficial effects of H. discus hannai, an anti-inflammatory peptide (AAIP, abalone anti-inflammatory peptide) was purified from abalone intestines using consecutive HPLC purification system. In tandem MS analysis, the fragmentation results illustrate that the AAIP responsible for the nitric oxide (NO) inhibitory activity (IC50=55.8μM) has amino acid sequence as Pro-Phe-Asn-Glu-Gly-Thr-Phe-Ala-Ser (1175.2 Da). To investigate anti-inflammatory effect of AAIP on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and elucidated the molecular mechanism. The results show that the AAIP peptide suppresses LPS-induced production of nitric oxide (NO) via inducible nitric oxide synthase (iNOS) expression in a dose-dependent manner. It also significantly reduced the gene transcription of proinflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Furthermore, AAIP significantly suppresses phosphorylation of mitogen-activated protein kinases (MAPKs) such as p-p38 and p-JNK. These results indicated that AAIP inhibits LPS-induced inflammatory response via blocking of MAPK pathway in murine macrophages. Therefore, potent AAIP might suggest possibility for high valuable utilization and application as nutraceutical and therapeutic substances.