Emery Olivier, Schmidt Konstantin, Engel Philipp
Department of Fundamental Microbiology, University of Lausanne, CH-1015, Lausanne, Switzerland.
Mol Ecol. 2017 May;26(9):2576-2590. doi: 10.1111/mec.14058. Epub 2017 Mar 8.
Gut bacteria engage in various symbiotic interactions with their host and impact gut immunity and homeostasis in different ways. In honey bees, the gut microbiota is composed of a relatively simple, but highly specialized bacterial community. One of its members, the gammaproteobacterium Frischella perrara induces the so-called scab phenotype, a dark-coloured band that develops on the epithelial surface of the pylorus. To understand the underlying host response, we analysed transcriptome changes in the pylorus in response to bacterial colonization. We find that, in contrast to the gut bacterium Snodgrassella alvi, F. perrara causes strong activation of the host immune system. Besides pattern recognition receptors, antimicrobial peptides and transporter genes, the melanization cascade was upregulated by F. perrara, suggesting that the scab phenotype corresponds to a melanization response of the host. In addition, transcriptome analysis of hive bees with and without the scab phenotype showed that F. perrara also stimulates the immune system under in-hive conditions in the presence of other gut bacterial species. Collectively, our study demonstrates that the presence of F. perrara influences gut immunity and homeostasis in the pylorus. This may have implications for bee health, because F. perrara prevalence differs between colonies and increased abundance of this bacterium has been shown to correlate with dietary alteration and impaired host development. Our transcriptome analysis sets the groundwork for investigating the interplay of bee gut symbionts with the host immune system.
肠道细菌与其宿主进行各种共生相互作用，并以不同方式影响肠道免疫和内环境稳态。在蜜蜂中，肠道微生物群由相对简单但高度特化的细菌群落组成。其中一个成员，γ-变形菌Frischella perrara会诱发所谓的结痂表型，即在幽门上皮表面形成的一条深色带。为了解潜在的宿主反应，我们分析了幽门在细菌定植后的转录组变化。我们发现，与肠道细菌Snodgrassella alvi不同，F. perrara会强烈激活宿主免疫系统。除了模式识别受体、抗菌肽和转运蛋白基因外，F. perrara还上调了黑化级联反应，这表明结痂表型对应于宿主的黑化反应。此外，对有和没有结痂表型的蜂巢蜜蜂进行的转录组分析表明，在蜂巢条件下，在存在其他肠道细菌物种的情况下，F. perrara也会刺激免疫系统。总体而言，我们的研究表明，F. perrara的存在会影响幽门中的肠道免疫和内环境稳态。这可能对蜜蜂健康有影响，因为不同蜂群中F. perrara的流行率不同，并且已证明这种细菌丰度的增加与饮食改变和宿主发育受损有关。我们的转录组分析为研究蜜蜂肠道共生体与宿主免疫系统之间的相互作用奠定了基础。
