Division of Animal Infectious Diseases in State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
PLoS One. 2012;7(2):e31121. doi: 10.1371/journal.pone.0031121. Epub 2012 Feb 8.
Bacteria can use mammalian hormones to modulate pathogenic processes that play essential roles in disease development. Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry globally. Stress is known to contribute to the outcome of A. pleuropneumoniae infection. To test whether A. pleuropneumoniae could respond to stress hormone catecholamines, gene expression profiles after epinephrine (Epi) and norepinephrine (NE) treatment were compared with those from untreated bacteria. The microarray results showed that 158 and 105 genes were differentially expressed in the presence of Epi and NE, respectively. These genes were assigned to various functional categories including many virulence factors. Only 18 genes were regulated by both hormones. These genes included apxIA (the ApxI toxin structural gene), pgaB (involved in biofilm formation), APL_0443 (an autotransporter adhesin) and genes encoding potential hormone receptors such as tyrP2, the ygiY-ygiX (qseC-qseB) operon and narQ-narP (involved in nitrate metabolism). Further investigations demonstrated that cytotoxic activity was enhanced by Epi but repressed by NE in accordance with apxIA gene expression changes. Biofilm formation was not affected by either of the two hormones despite pgaB expression being affected. Adhesion to host cells was induced by NE but not by Epi, suggesting that the hormones affect other putative adhesins in addition to APL_0443. This study revealed that A. pleuropneumoniae gene expression, including those encoding virulence factors, was altered in response to both catecholamines. The differential regulation of A. pleuropneumoniae gene expression by the two hormones suggests that this pathogen may have multiple responsive systems for the two catecholamines.
细菌可以利用哺乳动物激素来调节在疾病发展中起重要作用的致病过程。胸膜肺炎放线杆菌是一种重要的猪呼吸道病原体，在全球范围内给养猪业造成了巨大的经济损失。应激被认为会影响胸膜肺炎放线杆菌感染的结果。为了测试胸膜肺炎放线杆菌是否能对应激激素儿茶酚胺做出反应，比较了肾上腺素（Epi）和去甲肾上腺素（NE）处理后细菌的基因表达谱与未处理细菌的基因表达谱。微阵列结果显示，在存在 Epi 和 NE 的情况下，分别有 158 个和 105 个基因表达差异。这些基因被分配到各种功能类别，包括许多毒力因子。只有 18 个基因受到两种激素的调节。这些基因包括 apxIA（ApxI 毒素结构基因）、pgaB（参与生物膜形成）、APL_0443（一种自转运黏附素）和编码潜在激素受体的基因，如 tyrP2、ygiY-ygiX（qseC-qseB）操纵子和 narQ-narP（参与硝酸盐代谢）。进一步的研究表明，细胞毒性活性在 Epi 的作用下增强，但在 NE 的作用下受到抑制，与 apxIA 基因表达的变化一致。尽管 pgaB 的表达受到影响，但生物膜形成不受两种激素中的任何一种影响。NE 诱导对宿主细胞的黏附，但 Epi 没有，这表明这两种激素除了 APL_0443 之外，还影响其他潜在的黏附素。这项研究表明，胸膜肺炎放线杆菌的基因表达，包括那些编码毒力因子的基因，对两种儿茶酚胺都发生了改变。两种激素对胸膜肺炎放线杆菌基因表达的差异调节表明，这种病原体可能有多种对两种儿茶酚胺的反应系统。
