Alabdullah Hussain A, Fox Lawrence K, Gay John M, Barrington George M
Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 99163-6610, USA.
Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 99163-6610, USA.
Vet Immunol Immunopathol. 2018 Feb;196:18-21. doi: 10.1016/j.vetimm.2017.12.008. Epub 2017 Dec 12.
Previously we had reported that exposure to high levels of glucocorticoids, and to unopsonized Mycoplasma bovis, has a negative interactive effect on bovine neutrophil function in vitro, and this interactive effect was a function of M. bovis strain differences. Here we hypothesized that in vitro treatment of bovine neutrophils by glucocorticoid would impair phagocytosis of opsonized M. bovis compared to non-treated neutrophils and such impairment would be a function of M. bovis strain differences. Neutrophils isolated from 20 mid-lactation cows were treated with immunosuppressive dose of 5 × 10 M dexamethasone or placebo and incubated with one of four opsonized M. bovis strains that had been isolated from bovine origin. After incubation neutrophil function measured included: percentage reduction in log of M. bovis CFU/ml, percentage of phagocytizing neutrophils, phagocytized M. bovis per neutrophil, and killed M. bovis per neutrophil. Least square means of all neutrophil groups were contrasted using linear mixed-effects models. Effects due to strain, treatment, and their interaction on neutrophil function measured by the number of phagocytized M. bovis per neutrophil and number of killed M. bovis per neutrophil were different (P < 0.05). However, no significant strain by treatment interaction effect on percentage reduction in log of M. bovis CFU/ml was found. Neither a strain nor a strain by treatment interaction was found to affect the percentage phagocytizing neutrophils. These findings might explain in part the association of stressful events with subsequent outbreaks of Mycoplasma bovis associated bovine diseases.
此前我们曾报道，暴露于高水平糖皮质激素以及未调理的牛支原体环境中，会对体外培养的牛中性粒细胞功能产生负面交互作用，且这种交互作用是牛支原体菌株差异的一种表现。在此，我们假设，与未处理的中性粒细胞相比，用糖皮质激素体外处理牛中性粒细胞会损害其对调理牛支原体的吞噬作用，且这种损害是牛支原体菌株差异的一种表现。从20头处于泌乳中期的奶牛中分离出中性粒细胞，用免疫抑制剂量的5×10⁻⁶M地塞米松或安慰剂进行处理，然后与从牛源分离出的四种调理牛支原体菌株之一一起孵育。孵育后测量的中性粒细胞功能包括：牛支原体CFU/ml对数的降低百分比、吞噬中性粒细胞的百分比、每个中性粒细胞吞噬的牛支原体数量以及每个中性粒细胞杀死的牛支原体数量。使用线性混合效应模型对比所有中性粒细胞组的最小二乘均值。菌株、处理及其交互作用对每个中性粒细胞吞噬的牛支原体数量和每个中性粒细胞杀死的牛支原体数量所测量的中性粒细胞功能的影响不同（P<0.05）。然而，未发现菌株与处理的交互作用对牛支原体CFU/ml对数降低百分比有显著影响。未发现菌株或菌株与处理的交互作用会影响吞噬中性粒细胞的百分比。这些发现可能部分解释了应激事件与随后牛支原体相关牛病爆发之间的关联。
