IHAP, Université de Toulouse, INRA, ENVT, Toulouse, France.
ISP, INRA, Université de Tours, UMR1282, Nouzilly, France.
Sci Rep. 2017 Jun 13;7(1):3441. doi: 10.1038/s41598-017-03724-7.
Current vaccines to Escherichia coli mastitis have shown some albeit limited efficacy. Their mode of action has not been documented, and immune responses protecting the mammary gland against E. coli are not completely understood. To improve our knowledge of mammary gland immune protection, cows immunized either intramuscularly or intramammarily with the E. coli P4 were submitted to a homologous mastitis challenge. A third group of mock-immunized cows serve as challenge controls. Local immunization modified favorably the course of infection, by improving bacterial clearance while limiting inflammation. Systemic clinical signs and reduction in milk secretion were also contained. This occurred with a modification of the cytokine profile, such as an increase in IFN-γ and a reduction in TNF-α concentrations in milk. Concentrations of IL-17A and IL-22 increased in milk at the onset of the inflammatory response and remained high up to the elimination of bacteria, but concentrations did not differ between groups. Accelerated bacteriological cure was not linked to an increase in the initial efficiency of phagocytosis in milk. Results support the idea that antibodies did not play a major role in the improvement, and that cell-mediated immunity is the key to understanding E. coli vaccine-induced protection of the mammary gland.
目前针对大肠杆菌乳腺炎的疫苗已显示出一定的效果，但效果有限。它们的作用机制尚未得到证实，针对大肠杆菌保护乳腺的免疫反应也不完全清楚。为了增进我们对乳腺免疫保护的认识，我们对肌肉注射或乳房内注射大肠杆菌 P4 的奶牛进行了同源乳腺炎挑战。第三组模拟免疫的奶牛作为挑战对照。局部免疫通过改善细菌清除率同时限制炎症，从而有利地改变了感染过程。全身临床症状和产奶量减少也得到了控制。这伴随着细胞因子谱的改变，例如牛奶中 IFN-γ浓度增加和 TNF-α浓度降低。在炎症反应开始时，牛奶中 IL-17A 和 IL-22 的浓度增加，并一直保持高位，直到细菌消除，但两组之间的浓度没有差异。加速细菌学治愈与牛奶中初始吞噬作用效率的增加无关。结果支持这样一种观点，即抗体在改善方面没有发挥主要作用，细胞介导的免疫是理解大肠杆菌疫苗诱导的乳腺保护的关键。
