College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, 100193, Beijing, P. R. China.
College of Life Sciences and Food Engineering, Hebei University of Engineering, 056038, Handan, Hebei, P.R. China.
BMC Vet Res. 2021 Jan 19;17(1):37. doi: 10.1186/s12917-020-02738-0.
Klebsiella pneumoniae, an environmental pathogen causing mastitis in dairy cattle, is often resistant to antibiotics. K. pneumoniae was used as the host bacteria to support bacteriophage replication; 2 bacteriophages, CM8-1 and SJT-2 were isolated and considered to have therapeutic potential. In the present study, we determined the ability of these 2 bacteriophages to mitigate cytotoxicity, pathomorphological changes, inflammatory responses and apoptosis induced by K. pneumoniae (bacteriophage to K. pneumoniae MOI 1:10) in bovine mammary epithelial cells (bMECs) cultured in vitro.
Bacteriophages reduced bacterial adhesion and invasion and cytotoxicity (lactate dehydrogenase release). Morphological changes in bMECs, including swelling, shrinkage, necrosis and hematoxylin and eosin staining of cytoplasm, were apparent 4 to 8 h after infection with K. pneumoniae, but each bacteriophage significantly suppressed damage and decreased TNF-α and IL-1β concentrations. K. pneumoniae enhanced mRNA expression of TLR4, NF-κB, TNF-α, IL-1β, IL-6, IL-8, caspase-3, caspase-9 and cyt-c in bMECs and increased apoptosis of bMECs, although these effects were mitigated by treatment with either bacteriophage for 8 h.
Bacteriophages CM8-1 and SJT-2 mitigated K. pneumoniae-induced inflammation in bMECs cultured in vitro. Therefore, the potential of these bacteriophages for treating mastitis in cows should be determined in clinical trials.
肺炎克雷伯菌是一种环境病原体，可导致奶牛乳腺炎，常对抗生素产生耐药性。本研究将肺炎克雷伯菌作为宿主菌支持噬菌体复制，分离并鉴定了 2 株具有治疗潜力的噬菌体 CM8-1 和 SJT-2。本研究旨在确定这 2 株噬菌体在体外培养的奶牛乳腺上皮细胞（bMEC）中减轻由肺炎克雷伯菌（噬菌体与肺炎克雷伯菌的 MOI 为 1:10）引起的细胞毒性、病理形态变化、炎症反应和细胞凋亡的能力。
噬菌体减少了细菌的黏附和侵袭以及细胞毒性（乳酸脱氢酶释放）。感染肺炎克雷伯菌 4-8 小时后，bMEC 出现明显的形态变化，包括肿胀、收缩、坏死和胞浆苏木精和伊红染色，而每种噬菌体均显著抑制损伤并降低 TNF-α 和 IL-1β 浓度。肺炎克雷伯菌增强了 bMEC 中 TLR4、NF-κB、TNF-α、IL-1β、IL-6、IL-8、caspase-3、caspase-9 和 cyt-c 的 mRNA 表达，并增加了 bMEC 的细胞凋亡，但用噬菌体处理 8 小时可减轻这些效应。
噬菌体 CM8-1 和 SJT-2 减轻了体外培养的 bMEC 中肺炎克雷伯菌诱导的炎症。因此，应在临床试验中确定这些噬菌体治疗奶牛乳腺炎的潜力。
