Refined Deep-Sea Water Suppresses Inflammatory Responses via the MAPK/AP-1 and NF-κB Signaling Pathway in LPS-Treated RAW 264.7 Macrophage Cells

Atopic dermatitis (AD) is a type of inflammatory skin disease caused by genetics, immune system dysfunction, and environmental stresses. It is, however, still considered to be a refractory disease. Macrophages are inflammatory immune cells that infiltrate the skin and induce inflammation. We investigated the effect of refined deep-sea water (RDSW) on lipopolysaccharide (LPS)-induced inflammatory response in RAW 264.7 macrophage cells. The results showed that RDSW suppressed the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Furthermore, nitric oxide, a product of iNOS, and prostaglandin (PG) D₂ and PGE₂, products of COX-2, were significantly inhibited by RDSW in a hardness-dependent manner. Moreover, we found that RDSW reversed the release of histamines and regressed the mRNA expressions and production of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-10, and vascular endothelial growth factor, in a hardness-dependent manner. We also found that the suppressive effect of RDSW on LPS-induced inflammatory responses was regulated by the inhibition of NF-κB nuclear translocation, and ERK 1/2 and JNK 1/2 mediated the suppression of c-Jun and c-Fos expressions. In conclusion, the present investigation suggests the possibility that RDSW may be used to treat and/or prevent inflammatory diseases, including AD.