| Malathion(MT)and chlorpyrifos(CPF)are two common organophosphorus pesticides used worldwide for their function of increasing yields by controlling pests effectively.Walnut polyphenol extract(WPE)possesses strong antioxidant,anti-inflammatory and anti-cancer properties,which could alleviate toxic effects induced by toxic chemicals on humans and other mammals effectively.Based on the determination that MT and CPF induced immunotoxicity to mouse splenic lymphocytes,this paper investigated the effects of WPE on the immunotoxicity induced by MT and CPF,and explored the related mechanism.The main findings were showed as follows:(1)MT and CPF both significantly inhibited splenocytes viability,while WPE significantly alleviated the inhibitory effects of MT and CPF on splenocytes viability in a concentration-dependent manner.(2)MT selectively inhibited splenic T lymphocytes viability and the percentage content of CD3~+,CD4~+,and CD8~+T cells,while CPF selectively inhibited the viability of splenic B lymphocytes and the percentages of CD19~+B cells.WPE significantly increased the splenic lymphocytes vitality and upregulated the percentages of splenic lymphocytes subpopulations,and effectively alleviated MT and CPF-induced proliferative toxicity in splenic lymphocytes.(3)MT significantly decreased the levels of T cell-related cytokines interleukin(IL)-2,interferon(IFN)-?,IL-4 and granzyme B.CPF significantly suppressed the secretion of B cell-related cytokines IL-6.However,WPE significantly restored the function of cytokine secretion in splenocytes exposed to MT and CPF and effectively relieved the immunotoxicity of MT and CPF on splenocytes.(4)MT and CPF both induced abnormal expression of apoptosis-related genes,respectively increased the ratio of BAX/BCL-2 and up-regulated the expression of P53 in splenic T and B lymphocytes.WPE suppressed MT and CPF-induced splenic lymphocytes immunotoxicity by reducing the ratio of BAX/BCL-2 and the expression of P53,and restoring the apoptosis-related genes to normal levels,and recovering splenic lymphocytes viability in splenic T and B lymphocytes exposed to MT and CPF.(5)MT and CPF significantly increased hydroxyl radical(·OH),malondialdehyde(MDA)levels and inhibited superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),catalase(CAT)activity and down-regulated glutathione(GSH)content in splenic T or B lymphocytes.However,WPE significantly reduced the levels of·OH and MDA,up-regulated the activities of SOD,GSH-Px,and CAT,and up-regulated the level of GSH in splenic T and B lymphocytes exposed to MT and CPF.WPE inhibited MT and CPF-induced oxidative stress and relieved the oxidative toxicity of MT and CPF on splenic lymphocytes.(6)MT and CPF respectively increased the expression of NADPH oxidase(NOX)-2 and double oxidase(DUOX)-1 in splenic T and B lymphocytes.WPE significantly reduced the overexpression of NOX-2 and DUOX-1 induced by MT and CPF in splenic T and B lymphocytes.The results showed that WPE could reduce oxidative stress by reducing the overexpression of NOX-2 and DUOX-1,thus relieving immunotoxicity of MT and CPF.(7)MT markedly increased the expression of Toll-like receptors(TLR)-4 in splenic T lymphocytes but did not change that of TLR-7.CPF markedly increased the expression of TLR-7 in splenic B lymphocytes but did not affect that of TLR-4.These results indicated that MT and CPF increased the expression of NOX-2 and DUOX-1 by acting on different biological targets TLR-4 and TLR-7,respectively.WPE significantly inhibited the overexpression of TLRs in splenic lymphocytes.The results of this study indicated that apoptosis and oxidative stress were the main mechanisms of MT-and CPF-induced immunotoxicity in splenic lymphocytes.WPE could effectively alleviate the immunotoxicity induced by MT and CPF.The main mechanisms were to restore the expression of apoptosis-related genes and down-regulate the expression of TLRs in splenic lymphocytes,thereby inhibiting the overexpression of NOX-2 and DUOX-1,reducing the level of oxidative stress,and alleviating the immunotoxicity of MT and CPF. |
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