Internalization of S. mutans in vascular endothelial cells

描述（由申请人提供）：变形链球菌（Sm）长期以来被认为是人类最常见的感染性疾病龋齿的主要病原体。更不受重视的是它在口腔外感染中的作用。Sm是一种常见于人类细菌的条件致病菌，是感染性心内膜炎（IE）的病原体。IE是一种内皮层的瓣膜赘生物，是一种严重的心血管疾病，通常与牙科手术直接相关。现在有强有力的证据表明，Sm与出血性中风有关，出血性中风发生在大脑血管破裂时。此外，流行病学和DNA测序证据支持Sm对动脉粥样硬化的贡献作用。动脉粥样硬化是一种复杂的炎症性疾病，影响中型和大型动脉，是美国的主要死因。这些疾病的共同点是它们是心血管系统疾病。病原体附着和侵入内皮组织的能力先前已被证明是IE中的毒力所需的，并且侵入内皮细胞的能力已被证明与心内膜炎的严重程度相关。我们以前曾报道，特定菌株的Sm可以侵入人心血管主动脉内皮细胞（HCAEC）。新的数据表明，HCAEC侵袭表型与编码胶原结合蛋白Cnm的基因的存在相关，并且cnm的缺失使得菌株不能侵袭。Sm OMZ175，一种表达Cnm的菌株，在加速动脉粥样硬化的小鼠模型中与对照小鼠相比产生显著的病理学。细胞内病原体已经进化出多种途径和机制来进入、运输和在真核细胞内存活。因此，进入模式在决定细菌命运方面起着重要作用。目前还没有关于Sm进入细胞的细胞事件的报道。我们的总体假设是，菌株的Sm表达Cnm，如我们的模式生物OMZ175，能够坚持，进入，并坚持在HCAEC和进入的机制是至关重要的运输和生存的Sm细胞内。我们的工作假设，以测试在这个拟议的项目是，侵入性Sm进入内皮细胞使用特定的机制，Cnm在此条目中发挥了核心作用。了解一种普遍存在的口腔病原体的特定菌株获得的将其毒力扩展到口腔外的位点的机制，将进一步深入了解粘附素介导的链球菌与其宿主相互作用的分子细节。本申请的具体目的是1）确定Sm进入HCAEC的机制和2）确定Cnm在进入过程中的贡献。我们自己的数据和其他人的数据表明，侵袭性菌株的Sm也侵入口腔细胞，可以检测到predentate儿童。此外，cnm现已在S. sanguinis，S. suis和S.老鼠因此，这些研究将具有超出CVD病理学的意义。此外，该项目将有助于有关cnm作为Sm的高毒力菌株的生物标志物的应用信息。

DESCRIPTION (provided by applicant): Streptococcus mutans (Sm) has long been recognized as a major pathogen of dental caries, the most common infectious disease in humans. What is much less appreciated is its role in extra-oral infections. Sm is an opportunistic pathogen frequently identified in human bacteremias and is an etiologic agent of infectious endocarditis (IE). IE, a valvular vegetation of the endothelial layer, is a serious cardiovascular disease with often fatal outcomes directly related to dental procedures. There is now strong evidence that Sm is involved in hemorrhagic stroke, which occurs when a blood vessel ruptures in the brain. Additionally, epidemiological and DNA sequencing evidence supports a contributing role of Sm to atherosclerosis. Atherosclerosis is a complex inflammatory disease afflicting medium and large sized arteries and is the leading cause of death in the USA. The commonality of these diseases is that they are diseases of the cardiovascular system. The ability of a pathogen to attach to and invade endothelial tissues has previously been shown to be required for virulence in IE and the ability to invade endothelial cells has been shown to correlate with endocardititis severity. We have previously reported that specific strains of Sm can invade human cardiovascular aortic endothelial cells (HCAEC). New data demonstrate that the HCAEC invasion phenotype correlates with the presence of a gene encoding a collagen binding protein, Cnm, and that deletion of cnm renders the strains unable to invade. Sm OMZ175, a strain that expresses Cnm, produces significant pathology compared to control mice in a mouse model of accelerated atherosclerosis. Intracellular pathogens have evolved multiple pathways and mechanisms to enter, traffic and survive within eukaryotic cells. Thus, the mode of entry plays a major role in determining bacterial fate. There are no reports about the cellular events that govern Sm entry into cells. Our overall hypothesis is that strains of Sm expressing Cnm, such as our model organism OMZ175, are able to adhere to, enter, and persist in HCAECs and that the mechanism of entry is critical to the trafficking and survival of Sm intracellularly. Our workig hypothesis to be tested in this proposed project is that invasive Sm enters endothelial cells using specific mechanisms and that Cnm plays a central role in this entry. Understanding the mechanisms that specific strains of a ubiquitous oral pathogen have acquired that expand its virulence to sites outside of the oral cavity would provide further insight into the molecular details of adhesin mediated streptococci interactions with its host. The specific aims of this application are 1) Determine the mechanism of entry of Sm into HCAEC and 2) Determine the contribution of Cnm in the entry process. Our own data and that of others indicate that invasive strains of Sm also invade oral cells and can be detected in predentate children. In addition, cnm has now been found in strains of S. sanguinis, S. suis and S. rattus. Therefore these studies will have significance beyond CVD pathology. In addition, this project would contribute information concerning the application of cnm as a biomarker for hypervirulent strains of Sm.