Preliminary cell culture models for subclinical mastitis in sheep

Ovine mastitis is defined as the inflammation of the sheep udder, most commonly caused in response to intramammary infections. Based on the occurrence of clinical signs, mastitis is characterized as either clinical or subclinical (SCM). The impact of ovine SCM on the overall sustainability of dairy sheep farms has been documented underpinning the significance of efficient diagnosis. Although SCM can be detected in cows, the performance and the validity of the methods used do not transfer in dairy sheep. This fact challenges the development of evidence-based ovine udder health management protocols and renders the detection and control of ovine mastitis rather problematic. Currently, cell culture-based models are being successfully used in biomedical studies and have also been effectively used in the case of bovine mastitis. The objective of the present study was to culture ovine primary mammary cells for the development of 2D and 3D cell culture-based models for the study of ovine SCM. Cells were infected by mastitis-inducing pathogens mimicking the pathogenesis of SCM as derived by natural intramammary infections. The secreted proteins were subjected to mass-spectrometry resulting in the identification of 79 distinct proteins. Among those, several had already been identified in healthy or mastitic milk, while others were detected for the first time in the ovine mammary secretome. The development of cell-based models for the early detection and the overall study of SCM has the potential to be applicable and beneficial for the udder health management in dairy sheep.

绵羊乳腺炎被定义为绵羊乳腺的炎症，其最常见的诱因是乳腺内感染。根据临床症状的有无，乳腺炎可分为临床型乳腺炎与亚临床型乳腺炎（subclinical mastitis, SCM）。已有研究证实绵羊亚临床型乳腺炎对奶绵羊养殖场的整体可持续性存在负面影响，这凸显了高效诊断技术的重要性。尽管奶牛亚临床型乳腺炎可通过现有方法检测，但这些检测方法的性能与有效性无法直接适用于奶绵羊。这一现状为构建循证的绵羊乳腺健康管理方案带来了挑战，也使得绵羊乳腺炎的检测与防控难度大幅提升。目前，基于细胞培养的模型已在生物医学研究中得到广泛应用，且在牛乳腺炎相关研究中也已取得良好效果。本研究的目标为体外培养绵羊原代乳腺细胞，以构建用于绵羊亚临床型乳腺炎研究的二维（2D）与三维（3D）细胞培养模型。研究中使用可模拟自然乳腺内感染所致亚临床型乳腺炎发病机制的致病病原体感染上述细胞。对细胞分泌的蛋白质进行质谱（mass spectrometry）分析后，共鉴定出79种不同的蛋白质。其中部分蛋白质已在健康牛乳或乳腺炎牛乳中被鉴定出，其余则为绵羊乳腺分泌组（secretome）中首次发现的蛋白质。本研究构建的基于细胞的模型，可用于亚临床型乳腺炎的早期检测与相关研究，有望为奶绵羊的乳腺健康管理提供实用且有益的解决方案。