Regulatory Effects Of Zinc On Immune Response In Weanling Pigs And Intestinal Epithelial Cell

Four in vivo and in vitro experiments were conducted in tiffs study to investigate nutritional regulatory effects of zinc on immune response in weanling pigs and porcine epithelial cells.Exp.1 Effects of dietary zinc level on performance and immune response of weanling pigsAn experiment was conducted to determine the effect of dietary zinc level on growth performance and immune function in normal weanling pigs.Treatments consisted of the following:1) a corn-soybean meal basal diet contained 36.75 mg/kg total Zn,2) basal diet+60 mg/kg added Zn as ZnSO₄,3) basal diet+120mg/kg added Zn as ZnSO₄.Each diet was fed to six pens of four pigs per pen.In Exp 1,the dietary zinc level had no effect on average daily growth(ADG),average daily feed intake(ADFI),or Feed conversion ratio(FCR).Concentrations of tissue and serum zinc were not affected.AIK ativity was increased.Metalodlionein(MT) concentration,MTmRNA level were not affected.Peripheral blood lymphocyte proliferation(PBLP) was not affected by dietary treatments.Supplementation of 120 mg/kg Zn decreased(p＜0.05) the antibody response to bovine serum albumin(BSA) on d 7 compared with pigs fed the basal diet,but not on d 14.Results indicate that the level of Zn recommended by NRC(1998) for weanling pigs was sufficient for optimal growth performance and immune responses.Exp.2 Effects of dietary zinc level and an inflammatory challenge on performance and immune response of weanling pigsAn experiments were conducted to determine the effect of dietary zinc level on growth performance and immune function in immunologically challenged weanling pigs.Treatments consisted of the following:1) a corn-soybean meal basal diet contained 36.75 mg/kg total Zn,2) basal diet+60 mg/kg added Zn as ZnSO₄,3) basal diet+120mg/kg added Zn as ZnSO₄.Each diet was fed to six pens of three pigs per pen.In Exp 2,LPS challenge did not effect on ADG,ADFI and FCR in the entire trial(from d 0 to 21).LPS challenge significantly decreased ADG and ADFI (p＜0.01) from d 7 to 14,but FCR was not affected.LPS challenge increased PBLP (p＜0.05) and serum concentration of interleukin-1(IL-1)(p＜0.01),whereas the antibody response to BSA and serum concentration of interleukin-2(IL-2) were not affected.Supplementation of Zn did not affect ADFI and FCR from d 7 to 14,but there was a trend for ADG to be enhanced with Zn supplementation(p＜0.10). Supplementation of Zn tended to increase PBLP(p＜0.10).Dietary treatment had no effect on the antibody response to BSA,concentrations of serum IL-1 and IL-2. Results indicate that the level of Zn recommended by NRC(1998) for weanling pigs was sufficient for optimal growth performance and immune responses.Zn requirements may be higher for pigs experiencing an acute phase response than for healthy pigs.Exp.3 Effects of zinc level and LPS on immune response of swine intestinal epithelial cell lines(IPEC-J2)Intestinal epithelial cells play an important role in the innate immune response against pathogenic bacteria in the lumen of the gut.In the present study,we determined the effects of LPS and zinc on immune response of porcine epithelial cell lines(IPEC-J2) by regarding mRNA expression of proinflammatory mediators,such as cytokines(TNF-α,TGF-β) and chemokine(IL-8) as representative marker.The results were as follows:1.The zinc content of cells was enhanced with Zn supplementation.Treatments with 50μmol/LZnSO₄ and 100μmol/LZnSO₄ increased cellular zinc uptake by 55.69%and by 98.75%,respectly,compared with control cells.Treatments with 50μmol/L and 100μmol/L zinc acetate increased zinc content of cells by 67.65% and 116.58%(P＜0.01),respectively.The expression of ZnT1,DMT1 and MT were upregulated with Zn concentration of medium(P＜0.05).In cells treated with 50μmol/L,the expression of DMT1mRNA reacheded peak(P＜0.01).2.After LPS challenge,zinc content of cells was decreased by 5.10%.However, treatments with 50μmol/LZnSO₄ and 100μmol/LZnSO₄ increased zinc content of cells by 27.36%and by 45.64%(P＜0.01) 98.75%,respectly,compared with control cells.Treatments with 50μmol/L and 100μmol/L zinc acetate increased zinc content of cells by 26.11%(P＜0.05) and 73.07%(P＜0.01),respectively.LPS challenge had no feffect on the expression of IL-8,TNF-αand MT(P＞0.05).The expression of ZnT1mRNA(P＜0.01) and MTmRNA(P＜0.05) were increased with Zn supplementation.In cells treated with 50μmol/L,the expression of DMT1mRNA reacheded peak(P＜0.01). 3.zinc resources and zinc levels had no effect on the expression of of TNF-α,IL-8 and TGF-β.4.LPS challenge upregulated the expression of IL-8(P＜0.01) and TNF-α(P＜0.05),but downregulated the expression of TGF-β(P＜0.01).After LPS challenge,supplementation of Zn upregulated the expression of IL-8,TNF-αand TGF-β,compared with untreated cells.Exp.4 Effects of zinc level and Cyclophosphamide(CP) on immune response of swine intestinal epithelial cell lines(IPEC-J2)Cyclophosphamide(CP) is a widely used anti-cancer prodrug,is effective for autoimmune diseases.It has been shown that CP suppresses B-cell function with decreased antibody production and enhances TNF-α-induced apoptotie cell death. In this study,We determined the effects of Cyclophosphamide(CP) and zinc on immune response of porcine epithelial cell lines(IPEC-J) by regarding mRNA expression of proinflammatory mediators,such as cytokines(TNF-a,TGF-β) and chemokine(IL-8) as representative marker.The results were as follows:1.The zinc content of cells was enhanced with Zn supplementation.2.After Cyclophosphamide challenge,zinc content of cells was decreased by 7.07%. However,treatments with 50μmol/LZnSO₄ and 100μmol/LZnSO₄ increased zinc content of cells by 4.54%and by 39.91%,respectly,compared with control cells. Treatments with 50μmol/L and 100μmol/L zinc acetate increased cellular zinc uptake by 7.92%and 22.52%,respectively.The expression of ZnT1mRNA was upregulated by(P＜0.01).However,the expression of DMT1 and MT were downregulated by (P＜0.01),compared with control cells.The expression of ZnT1mRNA and MTmRNA were upregulated by(P＜0.01) with Zn supplementation.But,the expression of DMT1mRNA was downregulated by(P＜0.05)3.After Cyclophosphamide challenge,the expression of IL-8 and TNF-αwere downregulated by(P＜0.05),but the expression of TGF-βwas affected.Compared with control cells,the expression of IL-8 mRNA was upregulated(P＜0.01).However, the expression of TGF-βand TNF-αwere not affected.Zn supplementation upregulated the expression of TGF-βand TNF-α(P＞0.05).Zn(zinc acetate)supplementation upregulated the expression of TGF-β,IL-8 and TNF-α(P＜0.05).zinc resources and zinc levels had no effect on the expression of TNF-α, IL-8 and TGF-β.ImplicationsThese results in vitro and in vivo showed that the level of Zn recommended by NRC(1998) for weanling pigs was sufficient for optimal growth performance and immune responses.Zn requirements may be higher for pigs experiencing an acute phase response than for healthy pigs.Zinc play an important role in the regulatory of immune respone in immunologically challenged weanling pigs and porcine epithelial cells...