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

Abstract

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 (Se^IV) 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.

Keywords: Immunotoxicity; Lead (Pb); Peptides; RAW264.7 macrophages; Rice; Se.