Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, 1907 ISU C-Drive, Ames, IA, USA.
Department of Animal Science, Iowa State University, Ames, IA, USA.
Biol Trace Elem Res. 2024 Dec;202(12):5489-5501. doi: 10.1007/s12011-024-04123-6. Epub 2024 Mar 5.
Zinc (Zn) is critical for immune function, and marginal Zn deficiency in calves can lead to suboptimal growth and increased disease susceptibility. However, in contrast to other trace minerals such as copper, tissue concentrations of Zn do not change readily in conditions of supplementation or marginal deficiency. Therefore, the evaluation of Zn status remains challenging. Zinc transporters are essential for maintaining intracellular Zn homeostasis, and their expression may indicate changes in Zn status in the animal. Here, we investigated the effects of dietary Zn supplementation on labile Zn concentration and Zn transporter gene expression in circulating immune cells isolated from feedlot steers. Eighteen Angus crossbred steers (261 ± 14 kg) were blocked by body weight and randomly assigned to two dietary treatments: a control diet (58 mg Zn/kg DM, no supplemental Zn) or control plus 150 mg Zn/kg DM (HiZn; 207 mg Zn/kg DM total). After 33 days, Zn supplementation increased labile Zn concentrations (as FluoZin-3 fluorescence) in monocytes, granulocytes, and CD4 T cells (P < 0.05) but had the opposite effect on CD8 and γδ T cells (P < 0.05). Zn transporter gene expression was analyzed on purified immune cell populations collected on days 27 or 28. ZIP11 and ZnT1 gene expression was lower (P < 0.05) in CD4 T cells from HiZn compared to controls. Expression of ZIP6 in CD8 T cells (P = 0.02) and ZnT7 in B cells (P = 0.01) was upregulated in HiZn, while ZnT9 tended (P = 0.06) to increase in B cells from HiZn. These results suggest dietary Zn concentration affects both circulating immune cell Zn concentrations and Zn transporter gene expression in healthy steers.
锌（Zn）对免疫功能至关重要，犊牛边缘性缺锌可导致生长不良和疾病易感性增加。然而，与铜等其他痕量矿物质不同，组织中的锌浓度在补充或边缘缺乏的情况下不易改变。因此，评估锌的状态仍然具有挑战性。锌转运蛋白对于维持细胞内锌的动态平衡至关重要，其表达可能表明动物的锌状态发生了变化。在这里，我们研究了日粮锌补充对来自育肥场阉牛循环免疫细胞中可利用锌浓度和锌转运体基因表达的影响。将 18 头安格斯杂交阉牛（261±14kg）按体重分为两组，并随机分配到两种日粮处理：对照日粮（58mg Zn/kg DM，无额外锌源）或对照+150mg Zn/kg DM（高锌；总锌含量 207mg Zn/kg DM）。经过 33 天，锌补充增加了单核细胞、粒细胞和 CD4 T 细胞中的可利用锌浓度（FluoZin-3 荧光）（P<0.05），但对 CD8 和 γδ T 细胞有相反的影响（P<0.05）。在第 27 或 28 天收集纯化的免疫细胞群体，分析锌转运体基因表达。与对照相比，HiZn 组 CD4 T 细胞中的 ZIP11 和 ZnT1 基因表达降低（P<0.05）。HiZn 组 CD8 T 细胞中的 ZIP6（P=0.02）和 B 细胞中的 ZnT7（P=0.01）表达上调，而 HiZn 组的 B 细胞中 ZnT9 则呈上调趋势（P=0.06）。这些结果表明，日粮锌浓度既影响循环免疫细胞中的锌浓度，又影响健康阉牛的锌转运体基因表达。
