Corl C M, Gandy J C, Sordillo L M
Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA.
J Dairy Sci. 2008 Aug;91(8):3067-78. doi: 10.3168/jds.2008-1066.
The bovine mammary gland responds to gram-negative pathogens by stimulating the production of cytokines and other proinflammatory mediators that orchestrate the migration of leukocytes into tissues. Platelet activating factor (PAF), interleukin 1 beta (IL-1 beta), IL-8, and intercellular adhesion molecule 1 (ICAM1) are among the several inflammatory factors involved in the early activation and migration of leukocytes into the mammary gland during the initial stages of coliform mastitis. Several different cell types within the mammary gland are capable of expressing these potent pro-inflammatory mediators. The objective of this study was to characterize the expression profile of vascular-derived inflammatory molecules that may play a role in the pathogenesis of bovine coliform mastitis. Isolated bovine mammary gland endothelial cells were stimulated in culture for up to 12 h with endotoxin obtained from Escherichia coli, and the temporal expression of proinflammatory cytokines and adhesion molecules relative to endogenous PAF biosynthesis was evaluated. Results from the in vitro time course experiment showed that vascular-derived PAF biosynthesis began as early as 30 min and peaked at 1 h following endotoxin challenge. The biosynthesis of PAF preceded the endotoxin-induced IL-1 beta, IL-8, and ICAM1 mRNA expression that increased after 1 h and reached peak expression between 4 and 12 h following stimulation. Inhibiting the effects of endogenous PAF with a receptor antagonist suggests that vascular-derived PAF is an early proinflammatory mediator that plays at least a partial role in the subsequent expression of IL-1 beta, IL-8, and ICAM1 during endotoxin challenge. Furthermore, endotoxin-induced PAF biosynthesis by bovine mammary gland endothelial cells is regulated to some extent by phospholipase D activity and phosphatidic acid production. The results from this study support the contention that mammary gland endothelial cells can contribute to the production of important proinflammatory mediators that are typically associated with coliform mastitis.
牛乳腺通过刺激细胞因子和其他促炎介质的产生来应对革兰氏阴性病原体，这些细胞因子和介质协调白细胞向组织的迁移。血小板活化因子（PAF）、白细胞介素1β（IL-1β）、IL-8和细胞间黏附分子1（ICAM1）是在大肠埃希菌性乳腺炎初始阶段参与白细胞早期活化和向乳腺迁移的几种炎症因子。乳腺内几种不同类型的细胞能够表达这些强效促炎介质。本研究的目的是描述血管源性炎症分子的表达谱，这些分子可能在牛大肠埃希菌性乳腺炎的发病机制中起作用。将分离的牛乳腺内皮细胞在培养中用从大肠杆菌获得的内毒素刺激长达12小时，并评估促炎细胞因子和黏附分子相对于内源性PAF生物合成的时间表达。体外时间进程实验的结果表明，血管源性PAF生物合成早在30分钟开始，并在内毒素攻击后1小时达到峰值。PAF的生物合成先于内毒素诱导的IL-1β、IL-8和ICAM1 mRNA表达，后者在1小时后增加，并在刺激后4至12小时达到峰值表达。用受体拮抗剂抑制内源性PAF的作用表明，血管源性PAF是一种早期促炎介质，在内毒素攻击期间，它至少在IL-1β、IL-8和ICAM1的后续表达中起部分作用。此外，牛乳腺内皮细胞的内毒素诱导的PAF生物合成在一定程度上受磷脂酶D活性和磷脂酸产生的调节。本研究的结果支持这样的观点，即乳腺内皮细胞可促成通常与大肠埃希菌性乳腺炎相关的重要促炎介质的产生。
