Role of sialoglycan binding in the pathogenesis of streptococcal endocarditis

唾液酸聚糖结合在链球菌心内膜炎发病机制中的作用

• 批准号: 10714047
• 负责人: Jose Aron Lopez
• 金额: $ 80.67万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-17 至 2027-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10714047
• 关键词: Address; Affect; Affinity; Animal Model; Antigens; Attenuated; Bacteria; Bacterial Adhesins; Binding; Binding Proteins; Biomechanics; Biomedical Engineering; Blood; Blood Cells; Blood Circulation; Blood Platelets; Cardiac; Cell Wall; Cells; Circulation; Coagulation Process; Collagen; Complex; Disease; Disease Progression; Disease model; Endocarditis; Endocardium; Endothelium; Event; Family; Fibrin; Flow Cytometry; Genes; Glycoproteins; Heart; Heart Valves; Human; Immobilization; In Vitro; Infection; Infective endocarditis; Lesion; Life; Ligands; Link; Measures; Mediating; Microbial Biofilms; Microfluidics; Modeling; Mutagenesis; Organism; Pathogenesis; Pathogenicity; Physiological; Plasma; Plasma Proteins; Platelet Activation; Polysaccharides; Production; Proteins; Rattus; Research; Role; Serine; Site; Site-Directed Mutagenesis; Stream; Streptococcus; Streptococcus gordonii; Streptococcus sanguis; Structure; Surface; Thrombosis; Thrombus; Trisaccharides; Variant; Vascular Endothelial Cell; Virulence; Virulent; Work; adhesion receptor; antigen binding; enhancing factor; healing; heart damage; hemodynamics; in vivo; insight; lactosamine; mechanotransduction; microorganism interaction; mutant; new therapeutic target; novel; novel therapeutics; oral streptococci; pathogen; platelet function; receptor; recruit; shear stress; sialic acid binding Ig-like lectin; single-cell RNA sequencing; sugar; von Willebrand Factor

PROJECT SUMMARY The oral streptococci are a major cause of infective endocarditis (IE). Several of these species express Siglec- like, serine-rich repeat (SRR) adhesins that bind a variety of O-linked sialoglycans on human glycoproteins and cells. Expression of the SRR adhesin GspB of Streptococcus gordonii M99 results in increased virulence in animal models of IE. This enhanced pathogenicity is thought to be due the interaction of GspB with the trisaccharide sialyl-T antigen (sTa, a core 1 sialoglycan) on the platelet receptor GPIb, leading to increased attachment of bacteria in the blood stream to cardiac valve surfaces and vegetation formation. Isogenic mutants of M99 expressing GspB variants that preferentially bind core 2 sialoglycans,(e.g., sialyl-lactosamine) are less virulent, as compared with the WT strain. These findings indicate that differences in the type of sialoglycan bound ("selectivity") affect the ability of organisms to both initiate and propagate endocardial infection, with some interactions enhancing pathogenesis, while other interactions reducing disease. We hypothesize that in vivo, the binding of streptococci in the bloodstream to sTa on platelets or cardiac surfaces helps initiate infection, and that this binding is enhanced by hemodynamic effects created by high shear flow. In contrast, binding to core 2 sialoglycans on blood cells may lead to increased bacterial clearance, thereby attenuating virulence. Subsequent interactions of bacteria on valves with core 1 versus core 2 sialoglycans may affect disease progression via different effects on platelet activation, clotting, or endothelial healing. To further address the roles of sialoglycan binding selectivity in the pathogenesis of IE, we will compare by flow the above isogenic strains for their binding to platelets, RBCs and WBCs in vitro. We will also examine whether these strains bind platelets that differ in GPIb sialoglycan content, and whether binding to sTa versus core 2 structures affects platelet activation. In addition, we will assess how selectivity impacts the attachment of bacteria to damaged cardiac surfaces, as modeled by microfluidic chambers lined with immobilized platelets, von Willebrand Factor, collagen or activated human vascular endothelial cells, and the effect of hemodynamic forces on binding. We will also explore the impact of selectivity on vegetation formation by assessing strain differences in triggering platelet contractility and effects on platelet-dependent endothelial healing. We will also compare vegetations produced in vivo by these strains for key features linked to virulence, including co- localization with platelet and biofilm production. These studies will provide novel insights as to how sialoglycan selectivity and hemodynamic forces affect the initiation and propagation of endocardial infection. By defining the mechanisms for these events, this research will redefine our understanding of the key steps in the pathogenesis of streptococcal IE. These concepts and findings will be broadly applicable to other endovascular pathogens, and will provide novel insights into microbial interactions with host glycans.

项目摘要 口腔链球菌是感染性心内膜炎（IE）的主要原因。这些物种中有几个表达了siglec- 就像，富含丝氨酸的重复（SRR）粘附在人糖蛋白上结合多种O连接的唾液酸糖果和 细胞。 Gordonii M99链球菌的SRR粘附素GSPB的表达导致病毒增加 IE的动物模型。人们认为这种增强的致病性被认为是GSPB与 Trisacharide siAllyl-T抗原（STA，核心1 sialoglycan）在血小板受体GPIB上，导致增加 细菌在血流中的附着在心脏瓣膜表面和植被形成。等源性 M99的突变体表达GSPB变体，优先结合核心2 sialoglycans（例如，辅助乙酰乳糖胺） 与WT菌株相比，毒力较少。这些发现表明类型的差异 Sialoglycan绑定（“选择性”）会影响生物体启动和传播心内膜的能力 感染，一些相互作用增强了发病机理，而其他相互作用减少了疾病。我们 假设在体内，血液中链球菌在血小板或心脏表面上的结合 有助于引发感染，并且通过高剪切流产生的血液动力学作用增强了这种结合。 相反，与血细胞上的核心2唾液聚糖结合可能会导致细菌清除率增加，从而 衰减病毒。细菌在瓣膜上与核1与核心2唾液的瓣膜上的随后相互作用 通过对血小板激活，闭合或内皮愈合的不同影响，可能会影响疾病的进展。 为了进一步解决Sialoglycan结合选择性在IE发病机理中的作用，我们将通过流量进行比较 上述等源性菌株在体外与血小板，RBC和WBC结合。我们还将检查是否 这些菌株结合了gpib sialoglycan含量不同的血小板，以及与sta与core 2的结合 结构会影响血小板激活。此外，我们将评估选择性如何影响 通过微流体室建模的细菌损坏心脏表面 von Willebrand因子，胶原蛋白或活化的人血管内皮细胞以及血液动力学的作用 绑定的力。我们还将通过评估菌株来探索选择性对植被形成的影响 触发血小板收缩力以及对血小板依赖性内皮愈合的影响的差异。我们也会 比较这些菌株在体内产生的植被的关键特征与病毒相关的关键特征，包括共同特征 血小板和生物膜产生的定位。 这些研究将提供有关唾液酸聚会的选择性和血液动力学如何影响的新见解。 心内膜感染的启动和传播。通过定义这些事件的机制，这项研究 将重新定义我们对链球菌IE发病机理的关键步骤的理解。这些概念和 调查结果将广泛适用于其他血管内病原体，并将提供新颖的见解 与宿主聚糖的微生物相互作用。