Li Shuaichen, Zheng Xiaoyan, Ding Mengyuan, Tao Ze, Zhang Jiantao, Zhang Na
College of Veterinary Medicine, Northeast Agricultural University, Harbin, China.
Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Northeast Agricultural University, Harbin, China.
Front Vet Sci. 2020 Dec 18;7:580375. doi: 10.3389/fvets.2020.580375. eCollection 2020.
Laminitis in cattle is an important underlying cause of lameness, which leads to a significant reduction in economic and animal welfare. Nevertheless, the disordered pathological processes of laminitis remain unclear. Several proteinases are probably involved in the disorder of basement membrane (BM) metabolism in laminitis, for instance, matrix metalloproteinases (MMPs), neutrophil elastase (NE), and myeloperoxidase (MPO). This study aimed to investigate the change in proteolytic profile in circulating and lamellar tissues using an oligofructose (OF) overload-induced laminitis model in heifers. Twelve clinically healthy and nonlame Chinese Holstein heifers were recruited and randomly divided into two groups: OF-induced and control (CON). The OF-induced heifers group ( = 6) was administered 17 g/kg of body weight (BW) of OF dissolved in 2 L/100 kg of BW of tap water via the oral-rumen tube. The CON group ( = 6) was given an equal volume of tap water. The plasma samples were collected 0, 6, 12, 18, 24, 36, 48, 60, and 72 h after administration, and the lamellar samples were collected 72 h after euthanasia. The plasma samples were analyzed by zymography and reverse zymography. Histological examination, zymography, reverse zymography, and Western blot of lamellar samples were conducted. In the plasma of the OF-induced group, the pro-MMP9 activity increased from 36 h ( < 0.001) to 60 h ( < 0.05). Moreover, the plasma tissue inhibitors of metalloproteinase 1 (TIMP1) activity decreased after 18 h ( < 0.05), while the ratio of pro-MMP9 to TIMP1 and TIMP2 increased after 18 h ( < 0.001) and 48 h ( < 0.05), respectively. The act-MMP2, pro-MMP9, and act-MMP9 activities increased in the lamellar tissue of the OF-induced group compared with the CON group ( < 0.05). In addition, the expression of lamellar NE protein was higher in the OF-induced group ( < 0.01), while no change was found in lamellar MPO protein compared with the CON group. In conclusion, increased pro-MMP9 combined with decreased TIMP1 activity in the circulation might have caused the activation of blood neutrophils, while the activation of proteolytic enzymes in lamellar tissue probably led to the dysfunction of BM in the OF-induced group.
牛的蹄叶炎是跛行的一个重要潜在原因，会导致经济和动物福利显著下降。然而，蹄叶炎紊乱的病理过程仍不清楚。几种蛋白酶可能参与了蹄叶炎中基底膜（BM）代谢的紊乱，例如基质金属蛋白酶（MMPs）、中性粒细胞弹性蛋白酶（NE）和髓过氧化物酶（MPO）。本研究旨在利用低聚果糖（OF）过载诱导的小母牛蹄叶炎模型，研究循环和蹄叶组织中蛋白水解谱的变化。招募了12头临床健康且无跛行的中国荷斯坦小母牛，并随机分为两组：OF诱导组和对照组（CON）。OF诱导组的小母牛（n = 6）通过口腔-瘤胃管给予溶解于2 L/100 kg体重自来水中的17 g/kg体重的OF。CON组（n = 6）给予等体积的自来水。给药后0 h、6 h、12 h、18 h、24 h、36 h、48 h、60 h和72 h采集血浆样本，安乐死后72 h采集蹄叶样本。血浆样本通过酶谱法和反向酶谱法进行分析。对蹄叶样本进行组织学检查、酶谱法、反向酶谱法和蛋白质印迹分析。在OF诱导组的血浆中，前MMP9活性从36 h（P < 0.001）到60 h（P < 0.05）升高。此外，血浆金属蛋白酶组织抑制剂1（TIMP1）活性在18 h后降低（P < 0.05），而前MMP9与TIMP1和TIMP2的比值分别在18 h（P < 0.001）和48 h（P < 0.05）后升高。与CON组相比，OF诱导组蹄叶组织中的活化MMP2、前MMP9和活化MMP9活性升高（P < 0.05）。此外，OF诱导组蹄叶NE蛋白的表达较高（P < 0.01），而与CON组相比，蹄叶MPO蛋白未发现变化。总之，循环中前MMP9增加并伴有TIMP1活性降低可能导致血液中性粒细胞活化，而蹄叶组织中蛋白水解酶的活化可能导致OF诱导组中BM功能障碍。
