Microbial sphingolipids and suppression of host inflammation in periodontal disease

项目摘要 真核细胞SL是细胞膜的基本组成部分，是细胞内重要的信号分子。 SL的细菌合成知之甚少，几乎完全限于拟杆菌门。 这些微生物通常被认为是哺乳动物宿主的共生体。虽然微生物引起的慢性 炎症失调是软硬组织破坏和牙周病的中心特征 在发病机制中，矛盾的是，这种炎症不足以清除感染源。因此，颠覆 宿主免疫力的下降是这种疾病慢性性质的核心。研究表明， 牙龈杆菌，拟杆菌属的一员，独特地能够靶向和动态免疫抑制， 然而，人们对其中的基本机制知之甚少。值得注意的是，我们的研究已经阐明了 P. gingivalis SL在调节针对该生物体的引发的宿主免疫应答中的作用，并且我们已经表明， 这些SL从该生物体转移并整合到宿主细胞中--puristic被理解为 国际通讯系统。我们提出的研究的首要假设是， SL的增加为牙龈卟啉单胞菌和可能的其他口腔拟杆菌提供了免疫调节机制。 具体来说，我们发表的和初步的研究已经确定，牙龈卟啉单胞菌分泌含SL 与来自牙龈卟啉单胞菌的OMV相比，仅引起轻度炎症的外膜囊泡（OMV） 突变体不能合成SL，磷酸甘油-二氢神经酰亚胺（SL的一个子集） 含有OMV的细胞尤其擅长免疫抑制。我们建议SL-OMV是一种 精致的传递系统，形成牙龈卟啉单胞菌-宿主通信机制的基础，以控制 炎症我们提出的研究的目标是确定牙龈卟啉单胞菌SL如何促进OMV货物 负载以及随后这些SL-OMV如何调节宿主先天性炎症反应。我们将 在体外和体内询问牙龈卟啉单胞菌SL-OMV宿主感知。作为早期先天免疫反应 控制宿主在口腔等粘膜表面的反应，我们将采用独特的基因修饰技术， P. gingivalis菌株和从这些菌株分离的OMV，以确定涉及哪些OMV组分 镇压。分子、免疫学、成像、转录组学和生物化学技术将在 部署来阐明SL-OMV的潜在功能和宿主先天信号传导的机制。最后， 我们将使用口腔骨丢失模型来检查牙龈卟啉单胞菌菌株的毒力， SL的合成。这些研究的基本原理是，确定免疫调节机制， 口腔病原体将为治疗策略的开发提供主要目标。因此，长期 本研究的目的是阐明SL介导的OMV免疫传递的机制， 抑制，并确定细菌SL合成是否可以靶向用于治疗和预防 牙周病

PROJECT SUMMARY Eukaryotic SLs are the basic building blocks of cell membranes and serve as key signaling molecules. Bacterial synthesis of SLs is poorly understood, and almost entirely restricted to the phylum Bacteroidetes. These microbes are generally considered symbionts of mammalian hosts. Although microbe-elicited chronic dysregulated inflammation is central feature of soft and hard tissue destruction and periodontal disease pathogenesis, this inflammation is, paradoxically, insufficient to clear the source of infection. Thus, subversion of host immunity is central to the chronic nature of this disease. Research has shown that Porphyromonas gingivalis, a member of the Bacteroidetes is uniquely capable of targeted and dynamic immune suppression, yet little is known of the underlying mechanisms. Remarkably, our studies have illuminated the importance of P. gingivalis SL in regulating the elicited host immune response to this organism and we have shown that these SLs are transferred from this organism and incorporated into host cells – putatively understood as an interkingdom communication system. The overarching hypothesis of the research we propose is that synthesis of SLs affords P. gingivalis and possibly other oral Bacteroidetes a mechanism of immune regulation. Specifically, our published and preliminary studies have determined that P. gingivalis secretes SL-containing outer membrane vesicles (OMVs) that elicit only mild inflammation compared to OMVs from a P. gingivalis mutant incapable of synthesizing SLs, and that the phosphoglycerol-dihydrocerimides (a subset of SLs) containing OMVs are particularly adept at immune suppression. We are proposing that SL-OMVs are an exquisite delivery system that forms the basis of a mechanism of P. gingivalis-host communication to control inflammation. The goal of our proposed studies is to determine how P. gingivalis SLs contribute to OMV cargo loading and subsequently how these SL-OMVs modulate the host innate inflammatory response. We will interrogate host sensing of P. gingivalis SL-OMVs both in vitro and in vivo. As early innate immune responses control host responses at mucosal surfaces such as the oral cavity, we will employ unique genetically modified P. gingivalis strains, and OMVs isolated from these strains to determine which OMV-components are involved in suppression. Molecular, immunologic, imaging, and transcriptomic, and biochemical techniques will be deployed to elucidate the underlying functions of SL-OMVs and mechanisms of host innate signaling. Lastly, we will use oral bone loss modelling to examine the virulence of P. gingivalis strains that are altered in the synthesis of SLs. The rationale for these studies is that identifying immunoregulatory mechanisms used by oral pathogens will provide prime targets for the development of therapeutic strategies. Thus, the long-term goal of this research program is to elucidate the mechanisms underlying SL-mediated OMV delivered immune suppression and to determine if bacterial SL-synthesis can be targeted for treatment and prevention of periodontal disease.