An aqueous extract of Nomura's jellyfish ameliorates inflammatory responses in lipopolysaccharide-stimulated RAW264.7 cells and a zebrafish model of inflammation.

The recent mass emergence of Nomura's jellyfish (Nemopilema nomurai) has caused much economic and environmental damage. However, there is no innovative strategy to dispose of or utilize these jellyfish. Some reports suggest that the jellyfish may be bioactive resources and a source of important compounds with antibacterial activity. Here, we examined the effect of an aqueous extract of Nomura's jellyfish (AENJ) on lipopolysaccharide (LPS)-stimulated Raw 264.7 macrophages and a zebrafish model of inflammation and analyzed the underlying molecular mechanisms. AENJ downregulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA levels in LPS-stimulated Raw 264.7 macrophages, with no apparent cytotoxic effects. However, AENJ had no effect on expression of other inflammation-related genes such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and MCP-1. Furthermore, AENJ reduced expression of nerve injury-induced protein 1 (Ninj1), which is an important adhesion molecule, thereby reducing cell adhesion to the extracellular matrix (ECM) in vitro. The inhibitory effect of AENJ on leukocytes was confirmed in LPS-microinjected zebrafish larvae; AENJ reduced the number of the infiltrate accumulating at the site of inflammation. In addition, AENJ suppressed the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 in LPS-stimulated Raw 264.7 cells. Finally, AENJ blocked nuclear translocation of nuclear factor kappa B (NF-κB), a key transcription factor for inflammatory responses, in Raw 264.7 cells in a dose-dependent manner. Collectively, the data suggest that AENJ inhibits expression of COX and iNOS by blocking NF-κB signaling pathways and suppresses the activity of macrophages by downregulating Ninj1 and MMPs. Therefore, AENJ may be a useful preventive neutraceutical, or therapeutic agent against inflammatory disorders.