BACKGROUND Burkholderia mallei (Bm) is a facultative intracellular bacterial pathogen causing highly-fatal glanders in solipeds and humans. The ability of Bm to thrive intracellularly is thought to be related to exploitation of host immune response-related genes and pathways. Relatively little is known of the molecular strategies employed by this pathogen to modulate these pathways and evade intracellular killing. This manuscript seeks to fill gaps in the understanding of the interface between Bm and innate immunity by examining gene expression changes during infection of host monocytes. METHODS The transcriptome of Bm-infected human Mono Mac-6 (MM6) monocytes was profiled on Affymetrix Human Transcriptome GeneChips 2.0. Gene expression changes in Bm-infected monocytes were compared to those of Burkholderia thailandensis (Bt)-infected monocytes and to uninfected monocytes. The resulting dataset was normalized using Robust Multichip Average and subjected to statistical analyses employing a univariate F test with a random variance model. Differentially expressed genes significant at p < 0.001 were subjected to leave-one-out cross-validation studies and 1st and 3rd nearest neighbor prediction model. Significant probe sets were used to populate human pathways in Ingenuity Pathway Analysis, with statistical significance determined by Fisher's exact test or z-score. RESULTS The Pattern Recognition Receptor (PRR) pathway was represented among significantly enriched immune response-related human canonical pathways, with evidence of upregulation across both infections. Among members of this pathway, pentraxin-3 was significantly upregulated by Bm- or Bt-infected monocytes. Pentraxin-3 (PTX3) was demonstrated to bind to both Bt and Burkholderia pseudomallei (Bp), but not Bm. Subsequent assays did not identify a role for PTX3 in potentiating complement-mediated lysis of Bt or in enhancing phagocytosis or replication of Bt in human monocytes. CONCLUSION We report on the novel binding of PTX3 to Bt and Bp, with lack of interaction with Bm, suggesting that a possible evasive mechanism by Bm warrants further exploration. We determined that (1) PTX3 may not play a role in activating the lytic pathway of complement in different bacterial species and that (2) the opsonophagocytic properties of PTX3 should be investigated in different primary or immortalized cell lines representing host phagocytes, given lack of binding of PTX3 to MM6 monocytes.

中文翻译：

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对感染伯克霍尔德氏菌物种的人类单核细胞进行转录组分析，并探索五价毒素-3作为对生物体固有免疫反应的一部分。

背景技术大肠伯克霍尔德氏菌（Burkholderia Mallei，Bm）是一种兼性的细胞内细菌病原体，其在脂蛋白和人类中引起高度致命的腺体。Bm在细胞内生长的能力被认为与宿主免疫应答相关基因和途径的利用有关。对该病原体用于调节这些途径并逃避细胞内杀伤的分子策略的了解相对较少。该手稿旨在通过检查宿主单核细胞感染过程中的基因表达变化来填补对Bm与先天免疫之间接口的理解的空白。方法在Affymetrix人类转录组GeneChips 2.0上分析Bm感染的人类Mono Mac-6（MM6）单核细胞的转录组。将感染Bm的单核细胞的基因表达变化与感染Burkholderia thailandensis（Bt）的单核细胞和未感染的单核细胞进行比较。使用稳健多芯片平均值对所得数据集进行归一化，并使用带有随机方差模型的单变量F检验进行统计分析。对差异显着的p <0.001的基因进行留一法交叉验证研究以及第1和第3最近邻预测模型。在Ingenuity Pathway Analysis中，大量的探针被用于填充人类途径，其统计学显着性由Fisher精确检验或z评分确定。结果模式识别受体（PRR）途径在免疫应答相关的人类规范途径中非常丰富，在两种感染中都有上调的证据。在该途径的成员中，Pentraxin-3被Bm或Bt感染的单核细胞显着上调。Pentraxin-3（PTX3）被证明与Bt和假伯克霍尔德氏菌（Bp）结合，但与Bm不结合。随后的分析未发现PTX3在增强补体介导的Bt裂解或增强人类单核细胞中Bt的吞噬作用或复制中的作用。结论我们报道了PTX3与Bt和Bp的新型结合，缺乏与Bm的相互作用，这表明Bm可能的逃避机制值得进一步探索。