Inhibitory effect of Sea Lettuce (Ulva fasciata) Extract on Immune cells

Abstract

This report was designed to study inhibitory effect of sea lettuce (Ulva fasciata) extract (UFE) on pro-inflammatory cytokine production in bone marrow-derived macrophages (BMDM) and dendritic cells (BMDC). Inflammation is primary localized and protective response of host against microbial infection and autoimmune disorders. Macrophages and dendritic cells are major part of mammalian immune system and play important role in productions of pro-inflammatory cytokines. Thus, here we study the anti-inflammatory effect of UFE on CpG-stimulated BMDMs and BMDCs and human embryonic kidney cell line 293T(HEK293T) cells. The UFE (0-50 μg/mL) pre-treatment showed a dose dependant inhibitory effect on interlukin (IL)-12 p40, IL-6, and tumor necrosis factor (TNF)-α productions in CpG-stimulated BMDMs and BMDCs as compared to non-treated controls. The UFE pre-treatment exhibited strong inhibitory effect on the phosphorylation of p38 mitogen-activated protein kinase (MAPK) while it showed moderate inhibition on nuclear factor (NF)-κB activation as indirectly evaluated by degradation of IκBα. In activator protein (AP)-1 and NF-κB reporter gene assay, the UFE pre-treatment showed moderate inhibitory effect on both AP-1 and NF-κB dependent reporter gene activities. Thus, these results suggest that inhibitory effect of UFE on pro-inflammatory cytokine production may correlate with partial inhibition of both AP-1 and NF-κB pathways. Extracts from the U. fasciata has been previously reported to exhibit broad spectrum anti-bacterial activity and antioxidant activity. The present study suggests that UFE has an inhibitory effect on productions of pro-inflammatory cytokines, TLR9-dependent NF-κB and AP-1 activation and thus warrant further studies concerning potential uses of UFE. Hence, our data warrant further studies concerning potentials of sea lettuce for medicinal food.