The attenuated Mycoplasma bovis strain promotes apoptosis of bovine macrophages by upregulation of CHOP expression.
The attenuated Mycoplasma bovis strain promotes apoptosis of bovine macrophages by upregulation of CHOP expression.
复制标题
减毒牛支原体菌株通过上调 CHOP 表达促进牛巨噬细胞凋亡。
DOI：
10.3389/fmicb.2022.925209
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发表时间：
2022
影响因子：
5.2
通讯作者：
中科院分区：
文献类型：
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作者：
牛支原体(Mycodium bovis，M.bovis)是引起牛呼吸道疾病的主要病原之一，包括肺炎、乳房炎和关节炎，给养牛业造成了巨大的经济损失。在中国，用野生型牛分枝杆菌HB0801(P1)株体外连续培养150代，获得了一株减毒活疫苗株P150。利用感染的牛巨噬细胞系BoMac，本工作试图探讨P150衰减和保护性免疫反应的机制。首先，我们证明了牛分枝杆菌P150有效地触发了BoMac的细胞毒性和细胞凋亡，尽管细胞内存活率低于P1。对牛分枝杆菌P1和P150株感染BoMac后的转录本进行了测序，生物信息学分析鉴定出233个差异表达基因，其中185个上调，48个下调。进一步的基因本体论(GO)和京都基因和基因组百科全书(KEGG)途径丰富分析表明，大多数DEG与CHOP复合体、MAP激酶磷酸酶活性相关，并参与免疫反应中的IL-17信号通路、MAPK信号转导通路和细胞生长和死亡的P53信号通路。其中，在不同时间点，感染P150的BoMac细胞的C/EBP同源蛋白(CHOP)水平较感染P1的细胞显著上调，其上下游基因PERK、磷酸化eIF2α、ATF4和GADD45A在依赖PERK的内质网应激反应中显著增加。牛分枝杆菌诱导的BoMac细胞siCHOP基因敲除进一步证实了CHOP在细胞凋亡中的作用。结果表明，CHOP基因敲除增强了P150诱导的细胞凋亡，并显著提高了牛分枝杆菌P1和P150的细胞内存活率，尤其是对P150。这些数据表明，P150感染上调了CHOP的表达，从而增加了细胞凋亡，并在感染过程中介导了ER应激和细胞凋亡之间的串扰，从而导致了高细胞毒性和低细胞内存活率。
Mycoplasma bovis (M. bovis) is one of the major pathogens in the bovine respiratory disease complex, which includes pneumonia, mastitis, and arthritis and causes a great economic loss in the cattle industry. In China, a live-attenuated vaccine strain M. bovis P150 was obtained by a continuous culture of the wild-type strain M. bovis HB0801 (P1) in vitro for 150 passages. Using the infected bovine macrophage cell line BoMac, this work attempted to investigate the mechanism of P150 attenuation and protective immune response. To begin, we show that M. bovis P150 effectively triggered cytotoxicity and apoptosis in BoMac, although with lower intracellular survival than P1. The transcriptomes of BoMac after infection with M. bovis strains P1 and P150 were sequenced, and bioinformatic analysis identified 233 differentially expressed genes (DEGs), with 185 upregulated and 48 downregulated. Further Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses revealed that the majority of the DEGs were linked to CHOP complex, MAP kinase phosphatase activity and were involved in the IL-17 signaling pathway in immune response, MAPK signaling pathway in signal transduction, and p53 signaling pathway in cell growth and death. Among them, the level of C/EBP homologous protein (CHOP) was significantly upregulated in P150-infected BoMac compared to P1-infected cells at different time points, along with its upstream and downstream genes phosphorylated-PERK, phosphorylated-EIF2α, ATF4, and GADD45A increased in the PERK-dependent ER stress response. The role of CHOP in apoptosis was further verified by M. bovis-induced siCHOP knockdown in BoMac cells. The results showed that CHOP knockdown enhanced P150-induced apoptosis and dramatically increased the M. bovis P1 and P150 intracellular survival, particularly for P150. These data suggest that P150 infection upregulates CHOP expression, which can increase apoptosis and mediate a crosstalk between ER stress and apoptosis during infection, and hence, contribute to high cytotoxicity and low intracellular survival.