Inhibition of immunotoxicity of Pb2+-induced RAW264.7 macrophages by selenium species in selenium-enriched rice

Previous studies have revealed that Selenium-enriched rice protein hydrolysates (SPHs) could alleviate Pb2+-induced apoptosis in RAW264.7 macrophages. The purpose of the current study was to detect the effect of different selenium (Se) species on immunotoxicity of the Pb2+-induced RAW264.7 macrophages and explore the potential immunomodulatory mechanism. Herein, SPHs, an isolated SPHs fraction (SPHs-2), selenomethionine (SeMet), selenite (SeIV) were used to investigate their inhibitory effect and the impacts on the expression of cytokines and related protein kinases in immunomodulatory pathways. The results showed that, compared with Pb2+-only group, Se-containing components significantly enhanced the cell viability and effectively decrease nitric oxide (NO) content in Pb2+-induced RAW264.7 cells. Furthermore, compared with other Se species, SPHs-2 markedly decreased the secretion levels of pro-inflammatory cytokines TNF-α, NF-κB, IL-1β, MyD88, IL-6 and IL-8. Western blot results demonstrated that SPHs-2 effectively downregulated the expressions of IκB, IKKα, p38, and Erk1/2, and also successfully blocked the phosphorylation of these protein kinases. Our findings suggested that SPHs-2 effectively attenuate inflammatory response and inhibit the immunotoxicity of Pb2+ on RAW264.7 macrophages via regulating NF-κB/MAPK signaling pathways.