Mechanisms of Complement Evasion by Treponema denticola

描述(申请人提供)：牙周病是中年人最常见的传染病。齿密螺旋体是一种口腔细菌，与牙周炎的发展密切相关。牙周袋是牙齿和牙床之间的感染部位，沐浴在含有抗菌肽、免疫球蛋白和高度丰富的补体蛋白的沟槽液中。补体是一种先天性免疫系统，可以杀死革兰氏阴性细菌，标记病原体的破坏，并调节局部炎症。齿状毛滴虫可以通过产生FhbB和牙菌素来逃避补体介导的破坏。FhbB结合宿主负补体调节因子H，对细菌在人血清中的生存至关重要。Dentilisin能够裂解中央补体成分C3和C3b以及齿状血友病因子，可能会导致局部免疫反应的失调，导致炎症相关的组织损伤，这是牙周炎的一个标志。本项目的目的是从不同的临床分离株中对齿状毛滴虫的FhbB进行测序，然后应用重组蛋白的表达和纯化、表面等离子共振、免疫印迹和等位基因交换等生化手段来确定蛋白质序列的变异是否会影响FhbB：FH的相互作用和保护功能。此外，本研究的目的是通过纯化和质谱学鉴定牙菌素产生的因子H片段，该片段仍然与细胞结合。一些生化和细胞培养技术将被用来确定因子H片段是否保持调节活性，是否能保护齿状毛滴虫免受补体破坏，并改变全长FH的宿主细胞结合。更完整的齿状毛虫在牙周感染过程中引起的免疫失调的图景将有助于未来潜在的治疗和疫苗设计。 公共卫生相关性：了解与严重牙周病相关的细菌与免疫系统之间的相互作用至关重要。由这些病原体引起的炎症会导致与严重牙周病相关的组织损伤。该项目旨在表征齿密螺旋体和免疫系统之间的相互作用，从而为未来的治疗设计提供依据。

DESCRIPTION (provided by applicant): Periodontal disease is the most common infectious disease of middle-aged adults. Treponema denticola is an oral, bacterial species that is strongly associated with the development of periodontitis. The periodontal pocket, the site of infection between the tooth and the gums, is bathed in crevicular fluid containing antimicrobial peptides, immunoglobulin and highly abundant complement proteins. Complement is an innate immune system that can kill Gram-negative bacteria, mark pathogens for destruction, and modulate local inflammation. T. denticola can evade complement- mediated destruction by production of FhbB and dentilisin. FhbB binds the host negative complement regulator factor H and is critical to the survival of the bacterium in human serum. Dentilisin is capable of cleaving the central complement components C3 and C3b as well as factor H. T. denticola may cause a dysregulation of the local immune response leading to inflammation-associated tissue damage that is a hallmark of periodontitis. This project aims to sequence fhbB from a variety of clinical isolates of T. denticola then apply biochemical approaches such as recombinant protein expression and purification, surface plasmon resonance, immunoblotting and allelic exchange to determine if protein sequence variation affects the FhbB:FH interaction and protective function. Additionally, this study aims to identify a dentilisin generated factor H fragment, which remains bound to the cell, by purification and mass spectrometry. Several biochemical and cell culture techniques will be applied to determine if the factor H fragment retains regulatory activity, can protect T. denticola from complement destruction, and alter host cell binding of full length FH. A more complete picture of immune dysregulation caused by T. denticola during periodontal infection will aid in potential future therapeutic and vaccine design. PUBLIC HEALTH RELEVANCE: An understanding of the interaction between bacteria associated with severe periodontal diseases and the immune system is critical. Inflammation caused by these pathogens results in the tissue damage associated with severe periodontal diseases. This project aims to characterize the interactions between Treponema denticola and the immune system leading to future therapeutic design.