Aoyagi Kazuha, Owaki Keishi, Sakai Hiroki, Okada Ayaka, Inoshima Yasuo
Laboratory of Food and Environmental Hygiene, Joint Department of Veterinary Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
Laboratory of Veterinary Pathology, Joint Department of Veterinary Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
Pathogens. 2025 Jul 23;14(8):729. doi: 10.3390/pathogens14080729.
Bovine endometritis is a common postpartum disease that significantly impairs reproductive performance and reduces economic sustainability in dairy and beef cattle. It is primarily caused by gram-negative and -positive bacteria, triggering strong inflammatory responses in the endometrium. Serum amyloid A (SAA) is an acute-phase protein and precursor of amyloid A (AA) in AA amyloidosis. In cattle, multiple SAA isoforms have been identified; however, the biological functions of SAA3 remain unclear. Hence, this study investigated the role of SAA3 in bovine endometrial epithelial cells (BEnEpCs) following stimulation with gram-negative or -positive bacterial antigens. BEnEpCs were treated with lipopolysaccharide (LPS) and lipoteichoic acid (LTA) and, subsequently, the expression levels of SAA3 and SAA1 mRNA were compared by real-time PCR. To further investigate protein-level changes, immunocytochemistry (ICC) was performed to assess the expressions of SAA3 and SAA1. These analyses revealed that SAA3 mRNA expression was significantly enhanced by LPS and LTA, whereas SAA1 mRNA remained undetectable or showed only minimal responsiveness. Notably, only SAA3 protein expression increased in response to stimulation. These results indicate that SAA3 plays a crucial role in the innate immune response of BEnEpCs against gram-negative bacteria. Our findings may facilitate understanding of the innate immune activity in bovine uterus.
牛子宫内膜炎是一种常见的产后疾病，严重损害奶牛和肉牛的繁殖性能并降低其经济可持续性。它主要由革兰氏阴性菌和阳性菌引起，会在子宫内膜引发强烈的炎症反应。血清淀粉样蛋白A（SAA）是急性期蛋白，也是AA型淀粉样变性中淀粉样蛋白A（AA）的前体。在牛中，已鉴定出多种SAA亚型；然而，SAA3的生物学功能仍不清楚。因此，本研究调查了革兰氏阴性或阳性细菌抗原刺激后SAA3在牛子宫内膜上皮细胞（BEnEpCs）中的作用。用脂多糖（LPS）和脂磷壁酸（LTA）处理BEnEpCs，随后通过实时PCR比较SAA3和SAA1 mRNA的表达水平。为了进一步研究蛋白质水平的变化，进行了免疫细胞化学（ICC）以评估SAA3和SAA1的表达。这些分析表明，LPS和LTA显著增强了SAA3 mRNA的表达，而SAA1 mRNA仍未检测到或仅显示出最小的反应性。值得注意的是，仅SAA3蛋白表达在刺激后增加。这些结果表明，SAA3在BEnEpCs对革兰氏阴性菌的天然免疫反应中起关键作用。我们的研究结果可能有助于理解牛子宫中的天然免疫活性。
