Streptococcus uberis is an opportunistic pathogen involved in various infections of cattle. It is a well-known etiological agent of bovine mastitis and has recently also been linked to postpartum endometritis in dairy cows. S. uberis is frequently isolated from the uterus of postpartum cows but its actual contribution to host pathophysiology is unknown and information on S. uberis virulence factors potentially involved in the disease is lacking. To gain first insights into the role of S. uberis in the pathology of bovine endometritis, a cell-culture-based infection model was employed to study inflammatory host responses and investigate cytotoxic effects. A comprehensive strain panel, comprising 53 strains previously isolated from bovine uteri, was compiled and screened for known virulence factor genes. Isolates showing distinct virulence gene patterns were used to study their impact on cellular viability and influence on mRNA expression of pro-inflammatory factors in endometrial epithelial cells. Our study revealed that S. uberis negatively impacts the viability of endometrial epithelial cells and provokes an upregulation of specific pro-inflammatory factors, although with certain strains having a greater effect than others. Especially, mRNA expression of IL1A and CXCL8 as well as CXCL1/2 and PTGS2 was found to be stimulated by S. uberis. These results suggest that S. uberis might indeed contribute to the establishment of bovine endometritis.

乳房链球菌是一种机会病原体，涉及牛的各种感染。它是牛乳腺炎的著名病因，最近还与奶牛产后子宫内膜炎有关。乳房链球菌通常与产后母牛的子宫分离，但其对宿主病理生理的实际贡献尚不清楚，并且缺乏有关可能与该疾病有关的乳房链球菌毒力因子的信息。初步了解乳房链球菌的作用在牛子宫内膜炎的病理学中，采用基于细胞培养的感染模型来研究炎症宿主反应并研究细胞毒性作用。汇编并筛选了一个综合菌株组，其中包括先前从牛子宫中分离的53个菌株，并筛选了已知的毒力因子基因。使用显示出不同毒力基因模式的分离株来研究其对子宫内膜上皮细胞的细胞生存力和促炎因子mRNA表达的影响。我们的研究表明，乳房链球菌会对子宫内膜上皮细胞的活力产生负面影响，并引起特定促炎因子的上调，尽管某些菌株的作用比其他菌株更大。特别是IL1A和发现CXCL8以及CXCL1 / 2和PTGS2被乳房链球菌刺激。这些结果表明，乳房链球菌确实可能有助于牛子宫内膜炎的建立。