Gondaira Satoshi, Higuchi Hidetoshi, Nishi Koji, Iwano Hidetomo, Nagahata Hajime
Animal Health Laboratory, Graduate School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
Department of Veterinary Biochemistry, Graduate School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
Vet Microbiol. 2017 Feb;199:68-73. doi: 10.1016/j.vetmic.2016.12.022. Epub 2016 Dec 23.
Mycoplasma bovis is a significant pathogen in bovine infections including mastitis, pneumonia, arthritis and otitis media, and is the cause of large economic losses in beef and dairy farms. During infection with M. bovis, recruited neutrophils are not sufficient to eradicate M. bovis from the infection site. The release of neutrophil extracellular traps (NETs) is one of the innate immune responses of neutrophils but the effect of M. bovis on NET formation by bovine neutrophils has not yet been clarified. The objective of our research was to examine the effect of M. bovis on NET formation and the killing activity of bovine neutrophils. We showed that NETs were not detected following stimulation of neutrophils by M. bovis alone or with Phorbol 12-myristate 13-acetat (PMA). Reactive oxygen species production is essential for NET formation but the levels in neutrophils stimulated with M. bovis at multiplicity of infections of 10, 100, and 1000 were similar to those of unstimulated cells. NET formation induced by PMA stimulated neutrophils disappeared following the addition of M. bovis but this phenomenon was not observed when ethylenediaminetetraacetic acid (EDTA) was added. M. bovis colony forming units were significantly decreased by the addition of EDTA in the presence of NETs. Our results suggested that M. bovis infection alone did not induce NETs and that M. bovis nucleases, as hypothesis-based, contributed to resistance against the killing activity of NETs.
牛支原体是牛感染中的一种重要病原体，可引发乳腺炎、肺炎、关节炎和中耳炎等疾病，给肉牛和奶牛养殖场造成巨大经济损失。在牛支原体感染期间，募集的中性粒细胞不足以从感染部位清除牛支原体。中性粒细胞胞外陷阱（NETs）的释放是中性粒细胞的固有免疫反应之一，但牛支原体对牛中性粒细胞形成NETs的影响尚未阐明。我们研究的目的是检测牛支原体对NETs形成及牛中性粒细胞杀伤活性的影响。我们发现，单独用牛支原体或与佛波酯（PMA）一起刺激中性粒细胞后，未检测到NETs。活性氧的产生对NETs形成至关重要，但在感染复数为10、100和1000时用牛支原体刺激的中性粒细胞中的活性氧水平与未刺激细胞的相似。添加牛支原体后，PMA刺激诱导的中性粒细胞NETs形成消失，但添加乙二胺四乙酸（EDTA）时未观察到这种现象。在存在NETs的情况下添加EDTA可显著降低牛支原体菌落形成单位。我们的结果表明，单独的牛支原体感染不会诱导NETs形成，并且如基于假设所推测的，牛支原体核酸酶有助于抵抗NETs的杀伤活性。
