Anti-Inflammatory Effects of a Model Peptide, αAL14, via Regulation of ERK/MAPK and NF-κB Pathway on LPS-Stimulated RAW264.7 Macrophages

Inflammation is a biological response to infection, tissue damage, or external stimuli, and its understanding is crucial for disease prevention and treatment. αAL14, the model peptide, has been reported to have anti-angiogenic and anti-obesity effects. In this study, we investigated the anti-inflammatory properties in LPS-stimulated RAW264.7 cells.

To figure out the anti-inflammatory effect of αAL14, LPS-stimulated RAW264.7 cells were treated with αAL14, and cell viability assay, western blot, RT-qPCR, and immunofluorescence staining were performed.

αAL14 was confirmed to have no cytotoxicity in RAW264.7 macrophages, and a decrease in the production of pro-inflammatory mediators NO and PEG2 was observed in LPS-stimulated RAW264.7 cells. In addition, αAL14 regulated the protein expression of iNOS and COX-2 and decreased pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6, which were increased in LPS-treated cells at the transcriptional level. In LPS-treated RAW264.7 cells, phosphorylation of ERK1/2 was inhibited in the presence of αAL14, while p38 and JNK/SAPK were not. Furthermore, αAL14 treatment inhibited the phosphorylation of NF-κB and the translocation of p-ERK1/2 and NF-κB to the nucleus. Additionally, phosphorylation and degradation of IκBα were inhibited in LPS-stimulated RAW264.7 cells treated with αAL14. As a result, αAL14-induced phosphorylation of ERK1/2 and NF-κB in LPS-treated RAW264.7 cells was attenuated by suppressing the expression of pro-inflammatory mediators such as NO, PGE2, and cytokines.

Our study suggests that αAL14 possesses the efficacy of suppressing inflammatory responses in LPS-treated RAW264.7 macrophages.