Parés Sílvia, Cano-Garrido Olivia, Bach Alex, Ferrer-Miralles Neus, Villaverde Antonio, Garcia-Fruitós Elena, Arís Anna
Department of Ruminant Production, IRTA (Institut de Recerca i Tecnologia Agroalimentàries), 08140 Caldes de Montbui, Spain.
Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.
Animals (Basel). 2021 Nov 30;11(12):3415. doi: 10.3390/ani11123415.
The dry period is decisive for the milking performance of dairy cows. The promptness of mammary gland involution at dry-off affects not only the productivity in the next lactation, but also the risk of new intra-mammary infections since it is closely related with the activity of the immune system. Matrix metalloproteinase-9 (MMP-9) is an enzyme present in the mammary gland and has an active role during involution by disrupting the extracellular matrix, mediating cell survival and the recruitment of immune cells. The objective of this study was to determine the potential of exogenous administration of a soluble and recombinant version of a truncated MMP-9 (rtMMP-9) to accelerate mammary involution and boost the immune system at dry-off, avoiding the use of antibiotics. Twelve Holstein cows were dried abruptly, and two quarters of each cow received an intra-mammary infusion of either soluble rtMMP-9 or a positive control based on immunostimulant inclusion bodies (IBs). The contralateral quarters were infused with saline solution as negative control. Samples of mammary secretion were collected during the week following dry-off to determine SCC, metalloproteinase activity, bovine serum albumin, lactoferrin, sodium, and potassium concentrations. The soluble form of rtMMP-9 increased endogenous metalloproteinase activity in the mammary gland compared with saline quarters but did not accelerate either the immune response or involution in comparison with control quarters. The results demonstrated that the strategy to increase the mammary gland immunocompetence by recombinant infusion of rtMMP-9 was unsuccessful.
干奶期对奶牛的产奶性能至关重要。干奶时乳腺 involution 的迅速程度不仅影响下一泌乳期的生产力，还影响新的乳腺内感染风险，因为它与免疫系统的活性密切相关。基质金属蛋白酶-9（MMP-9）是一种存在于乳腺中的酶，在 involution 过程中通过破坏细胞外基质、介导细胞存活和免疫细胞募集发挥积极作用。本研究的目的是确定外源性给予截短型 MMP-9 的可溶性重组版本（rtMMP-9）以加速乳腺 involution 并在干奶时增强免疫系统的潜力，同时避免使用抗生素。12 头荷斯坦奶牛被突然干奶，每头奶牛的两个乳腺象限分别接受乳腺内注射可溶性 rtMMP-9 或基于免疫刺激包涵体（IBs）的阳性对照。对侧象限注射生理盐水作为阴性对照。在干奶后的一周内收集乳腺分泌物样本，以确定体细胞计数（SCC）、金属蛋白酶活性、牛血清白蛋白、乳铁蛋白、钠和钾的浓度。与注射生理盐水的象限相比，rtMMP-9 的可溶性形式增加了乳腺内源性金属蛋白酶活性，但与对照象限相比，既没有加速免疫反应也没有加速 involution。结果表明，通过重组注射 rtMMP-9 来提高乳腺免疫能力的策略未成功。
