Penicillin-binding protein of Ehrlichia chaffeensis: cytokine induction through MyD88-dependent pathway.
Penicillin-binding protein of Ehrlichia chaffeensis: cytokine induction through MyD88-dependent pathway.
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DOI：
10.1093/infdis/jis313
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发表时间：
2012-07
期刊：
影响因子：
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通讯作者：
M. Rahman;Zhihui Cheng;J. Matsuo;Y. Rikihisa
中科院分区：
文献类型：
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作者：
M. Rahman;Zhihui Cheng;J. Matsuo;Y. Rikihisa
背景人类单核细胞埃立克体病是由查菲埃立克体病引起的最流行的人畜共患病之一。虽然查菲乳杆菌缺乏完整的脂多糖和大部分肽聚糖生物合成基因，但它能诱导炎性细胞因子和趋化因子。诱导炎症的查菲埃利希菌成分和反应的宿主细胞途径尚不清楚。方法采用逆转录聚合酶链式反应和博西林FL结合实验分析青霉素结合蛋白(PBP)在查菲乳杆菌中的表达。接下来，研究了经高压液相层析纯化的重组PBP和天然的查菲原虫PBP在人单核细胞白血病细胞系THP-1和来自野生型和MyD88基因敲除小鼠的骨髓源巨噬细胞(BMDM)中诱导炎性细胞因子的能力。结果查菲埃希氏菌PBP在其细胞内的生活周期中表达上调。PBP可诱导THP-1细胞和骨髓基质细胞产生IL-8或CXCL_2、肿瘤坏死因子α、IL-1β和IL-10。PBP诱导的细胞因子依赖于MyD88。用青霉素亲和层析柱和互补实验从查菲乳杆菌裂解液中去除PBP，证实了天然PBP的细胞因子诱导活性。结论查菲埃希菌PBP的细胞因子诱导活性为研究查菲埃希氏菌感染的病原体相关分子模式和致病机制提供了新的思路。
BACKGROUND Human monocytic ehrlichiosis is one of the most prevalent tick-borne zoonoses caused by infection with Ehrlichia chaffeensis. Although E. chaffeensis lacks entire lipopolysaccharide and most peptidoglycan biosynthesis genes, it induces inflammatory cytokines and chemokines. Ehrlichia chaffeensis components that induce inflammation and the responsive host cell pathway are not known. METHODS Expression of penicillin-binding protein (PBP) in E. chaffeensis was analyzed by reverse-transcription polymerase chain reaction and Bocillin FL binding assay. Next, recombinant PBP, which was high-pressure liquid chromatography purified, and native PBP of E. chaffeensis were investigated for their ability to induce proinflammatory cytokines in the human monocytic leukemia cell line THP-1 and bone marrow-derived macrophages (BMDMs) from wild-type and MyD88 knockout mice. RESULTS Expression of PBP by E. chaffeensis was upregulated during its intracellular life cycle. PBP induced interleukin 8 or CXCL2, tumor necrosis factor α, interleukin 1β, and interleukin 10 in THP-1 cells and BMDMs. Cytokine induction by PBP was MyD88-dependent. Removal of PBP from E. chaffeensis lysate using penicillin affinity column and a complementation assay confirmed cytokine-inducing activity of native PBP. CONCLUSIONS The cytokine-inducing activity by E. chaffeensis PBP provides novel insights into pathogen-associated molecular patterns and pathogenesis of E. chaffeensis infection.