Activation of murine RAW264.7 macrophages by oligopeptides from sea cucumber (Apostichopus japonicus) and its molecular mechanisms

[Display omitted] •Small molecule oligopeptides extracted from sea cucumber (Apostichopus japonicus) (SCOP) were characterized.•SCOP enhanced the immune activity of RAW264.7 macrophages as measured by the release of NO, TNF-α and IL-6.•SCOP stimulated macrophages through the upregulation of the NF-κB and MAPK signaling pathways. Sea cucumbers are valuable marine foods as well as a source of traditional medicines with various bioactivities. Macrophage activation by small-molecule oligopeptides obtained from the sea cucumber Apostichopus japonicus (SCOP) were investigated. After SCOP were proven nontoxic by oral administration and CCK-8 assays, we measured immune-stimulatory mRNA, pro-inflammatory cytokines, and NO production levels and determined the molecular mechanism of macrophage stimulation. Our results demonstrated that SCOP upregulated both the mRNA levels and the secretion of NO, TNF-α, and IL-6 in a dose-dependent manner. More importantly, SCOP contributed to the stimulation of macrophages through the upregulation of the NF-κB and MAPK signaling pathways. Taken together, these results indicated that SCOP exerted macrophage activation effects on RAW264.7 cells and that they could potentially be used as a functional food supplement in treating immune suppression.