Protective Effects Of Zinc And NAC On Cytotoxicity Of Avian Macrophage Exposed To Cadmium In Vitro

Cadmium(Cd)is an extremely toxic heavy metal element which can injure many kinds of cells and organs in both human and animals.With the aggravation of cadmium pollution,cadmium accumulations in food is far higher than normal level,and the cadmium poisoning phenomenon on animal continuously increased.Poultry which live on phytophagous diet is under immediate threat of cadmium poisoning.Macrophage takes an important part in innate immune system,especially in the natural immune system.Cadmium exposure may cause macrophage cytotoxicity,which influence the immune function However,few research concerning the effect of cadmium on macrophage were reportedTo investigate the effects of cadmium induced cytotoxicity and immune adjustment on avian macrophage,the cadmium poisoning model was established successfully by adding 20 ?mol/L and 50?mol/L Cd2+ in the HD-11 cells culture medium,and discussed the toxic effect of different concentrations of cadmium on cytoskeleton,apoptosis rate,reactive oxygen species(ROS)content,level of mitochondrial membrane potential(MMP)and so on.At the same time,the gene transcription level of IL-1?,IL-8 and IL-10 in HD-11 cells were determined and studied the influence of cadmium on the immune function of macrophages.In addition,to explore the protective effects of Zn2+ and NAC against Cd2-induced cytotoxicity and immune function,HD-11 cells were treated with 20 ?mol/L Zn2' and 500?mol/L NAC.The regulation mechanism of Zn2' and NAC on cadmium poisoning macrophage was revealed through testing the gene transcription level of MTF-1 and MT in HD-11 cellsThe results are as follows(1)Cadmium poisoning caused degradation on cytoskeletal proteins,atrophy on cytoplasm and nucleus.With the increasing cadmium concentration,the structural damage of HD-11 cells was more serious.Zn2+ and NAC supplementation alleviated Cd2+-induced cell ultrastructure injury and protected the HD-11 cells(2)Cadmium poisoning led to a dose-and time-dependent increase in apoptotic rate(P<0.05),ROS content rise(P<0.05)and MMP decrease(P<0.05),Zn2+ or NAC supplementation alleviated appropriately Cd2+-induced apoptosis rate(6 h P<0.05;12 h P<0.01),reduced ROS content(P<0.05)and restored the level of MMP(P<0.05).The protective effect was more obvious when HD-11 cells were treated with Zn2+in combination with NAC,as compared to treating with Zn2+ or NAC alone(P<0.05).(3)Cadmium poisoning reduced significantly the gene expression level of IL-1? in HD-11 cells(P<0.01),the RNA expression level of IL-1(3 gene increased gradually after adding Zn2+ or NAC singly(P<0.05)and in combination(P<0.01),particularly combination of the two applications,which are more pronounced.There was no obvious changing difference could be observed about the expression of IL-8 gene in HD-11 cells exposed to 20 ?mol/L Cd2+for 6 h and 12 h(P>0.05),while the expression of IL-8 gene reduced when exposed to 50 ?mol/L Cd2+.Zn2+ and NAC supplementation could accelerate IL-8 gene expression,supplementing with Zn2+ or NAC alone increased the expression level of IL-8 gene(P<0.05).Compared with the effect of adding individually,combination of the two applications had more obvious growth tendency(P<0.01).In addition,cadmium poisoning also significantly suppress the expression of IL-10 gene in HD-11 cells treated with Cd2+ for 6 h and 12 h(P<0.05),Zn2+ supplementation could inhibit Cd2+-induced cytotoxicity and increase the expression level of IL-10 gene(P<0.05).While NAC supplementation produced obvious promotive effect in IL-10 gene expression level in HD-11 cells treated with Cd2+ for 12 h.Compared with the effect of adding Zn2+ or NAC individually,combination of the two applications had more obvious promotive tendency to the expression content of IL-10 gene.(4)Cadmium poisoning enhanced RNA expression of MT and MTF-1 in HD-11 cells(P<0.05),addition of Zn2+ synergistically enhanced RNA expression as compared to addition of NAC alone.Compared with the effect of adding Zn2+ individually,a combination of supplementations with NAC and Zn2+ could further increase the RNA expression of MT and MTF-1.Conclusion:Cadmium led to dose-and time-dependent structural lesions and cytokine secretion decline in HD-11 cells,Zn2+ and NAC supplementation can alleviate Cd2+-induced cytotoxicity and improve the expression level of cytokines in HD-11 cells and this protective effect was more obvious when combination of the two applications,as compared to Zn2+ or NAC supplementation alone.