Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland.
FOSS Analytical A/S, Foss Allé 1, 3400 Hillerød, Denmark.
J Dairy Sci. 2018 Jun;101(6):5362-5373. doi: 10.3168/jds.2017-14152. Epub 2018 Mar 15.
Intramammary infections induce the initiation of the inflammatory response, resulting in an increase in somatic cell count (SCC) in milk. The SCC includes several different types of cells but does not differentiate between them. On the contrary, the new differential somatic cell count (DSCC) parameter allows for the differentiation between 2 groups of cells: polymorphonuclear neutrophils (PMN) and lymphocytes versus macrophages. Therefore, the aim of this paper was to describe the changes of both DSCC and SCC during mastitis induced by cell wall components from typical mastitis-causing pathogens [lipopolysaccharide (LPS), Escherichia coli; lipoteichoic acid (LTA), Staphylococcus aureus] known to trigger different severities of mastitis. In addition, the effect the glucocorticoid prednisolone (PRED), which is known to attenuate the immune response in the mammary gland, was investigated. Twenty dairy cows were equally divided into 5 groups and treated with LPS, LTA, LPS+PRED, LTA+PRED, or a saline control. Milk samples were taken at the following time points: baseline (d -3, -2, and -1), right before treatment (d 0), 5 h after treatment (d 0.2), early cure phase (d 1 and 2), and late cure phase (d 3, 4, 5, 6, 7, and 14) and analyzed for DSCC and SCC. Mean DSCC values increased significantly from <60% at baseline and right before treatment to >81% 5 h after treatment and the early cure phase in all groups, except for the groups control and LTA+PRED. This increase clearly reflects a shift in cell populations to predominantly PMN. The SCC increased significantly following the stimulation, too, as expected. Interestingly, we observed cases where SCC increased moderately only whereas DSCC showed an evident increase, meaning that the shift in cell populations occurred even at low SCC levels. The PRED clearly lowered the cell migration in group LTA+PRED. This is the first ever study investigating DSCC during induced mastitis under controlled conditions. The combination of DSCC and SCC could be employed for the earlier detection of mastitis by revealing the shift in cell population independent from the SCC level. Furthermore, combining DSCC and SCC information could help to determine the stage of mastitis because we observed high DSCC and SCC results in the early stage of mastitis but evidently lower DSCC and high SCC in the cure phase. Hence, our results offer the first fundamental insights on how mastitis monitoring could be improved in the frame of dairy herd improvement programs.
乳腺炎感染会引发炎症反应，导致乳汁中体细胞计数（SCC）增加。SCC 包括几种不同类型的细胞，但不能对其进行区分。相反，新的差异体细胞计数（DSCC）参数可以区分 2 组细胞：多形核中性粒细胞（PMN）和淋巴细胞与巨噬细胞。因此，本文的目的是描述由已知引发不同严重程度乳腺炎的典型乳腺炎病原体[脂多糖（LPS）、大肠杆菌；脂磷壁酸（LTA）、金黄色葡萄球菌]细胞壁成分诱导的乳腺炎中 DSCC 和 SCC 的变化。此外，还研究了已知可减弱乳腺免疫反应的糖皮质激素泼尼松龙（PRED）的作用。20 头奶牛被平均分为 5 组，用 LPS、LTA、LPS+PRED、LTA+PRED 或生理盐水对照处理。在以下时间点采集奶样：基线（d-3、-2 和-1）、治疗前（d0）、治疗后 5 小时（d0.2）、早期治愈期（d1 和 2）和晚期治愈期（d3、4、5、6、7 和 14），并分析 DSCC 和 SCC。除对照组和 LTA+PRED 组外，所有组的平均 DSCC 值均从基线和治疗前的<60%显著增加至治疗后 5 小时和早期治愈期的>81%。这种增加清楚地反映了细胞群向主要多形核中性粒细胞的转移。正如预期的那样，SCC 也随着刺激而显著增加。有趣的是，我们观察到 SCC 仅中度增加而 DSCC 明显增加的情况，这意味着即使在 SCC 水平较低的情况下，细胞群也发生了转移。PRED 明显降低了 LTA+PRED 组的细胞迁移。这是首次在受控条件下研究诱导性乳腺炎期间的 DSCC。DSCC 和 SCC 的组合可用于通过独立于 SCC 水平揭示细胞群的转移来更早地检测乳腺炎。此外，结合 DSCC 和 SCC 信息可以帮助确定乳腺炎的阶段，因为我们在乳腺炎的早期阶段观察到高 DSCC 和 SCC 结果，但在治愈阶段则明显较低的 DSCC 和高 SCC。因此，我们的结果首次提供了关于如何在奶牛群改进计划框架内改进乳腺炎监测的基本见解。
