TNFα-mediated plasminogen activation on neutrophils is involved in the high plasmin activity in mammary secretion of drying-off cows

作者：Wen K Chou, Ting Yu, Shuen‐Ei Chen, Ho C Peh, Wen B Liu, Ming T Chen, Hajime Nagahata, Chai J Chang · 发表于：Journal of Dairy Research · 年份：2009 · DOI：10.1017/s0022029909990069 · 被引用次数：11 · 研究领域：Protease and Inhibitor Mechanisms、Cell Adhesion Molecules Research、Milk Quality and Mastitis in Dairy Cows

Interactions between inflammatory cytokines and plasminogen (Pg) activation system on immune cells are yet to be established. In previous studies we reported a somatic cell-associated elevation of proteolytic activity in mammary secretion of drying-off goats and cows. The purposes of the present study were to examine the role of TNF-alpha in polymorphonuclear neutrophil (PMN)-associated Pg activation, and the significance of this activation pathway for overall plasmin (Pm) activity in mammary secretion of drying-off cows. Results of experiments in vitro showed that the spontaneous Pg activation observed on fresh preparations of bovine blood PMN was completely blocked by anti bovine TNF-alpha antibody, and was further up-regulated by exogenous bovine TNF-alpha. Monitoring the parameters of mammary secretion of drying-off cows revealed that both somatic cell counts and differential PMN ratio was significantly elevated at weeks 1, 2 and 3 of milk stasis. Nevertheless, specific activity of soluble Pm in mammary secretion increased and the level of 17-kDa TNF-alpha decreased immediately following milk stasis. Iimmunoblotting revealed that although both 26-kDa pro-TNF-alpha and 17-kDa TNF-alpha were consistently present in somatic cells of mammary secretion collected at weeks 0, 1, 2 and 3 of milk stasis, only 26-kDa pro-TNF-alpha was present in somatic cells of milk during lactation. In-vitro assay indicated that cell-free mammary secretion of drying-off cows exerted no Pg activat...