Oral Pathogens and Dendritic Cell Subsets

描述（由申请人提供）：虽然牙龈卟啉单胞菌是复杂生物膜的一部分，但它唯一能够感染人口腔粘膜的粘膜下区域，因此它与CP中的有效抗原呈递细胞树突状细胞（DC）原位缔合。这些DC与CD 4 + T细胞形成有组织的免疫缀合物，称为口腔淋巴灶或OLF。DCs对牙龈卟啉单胞菌感染的免疫调节功能是我们实验室非常感兴趣的。牙龈卟啉单胞菌表达一种不寻常的免疫调节LPS和两种菌毛粘附素：67 kDa mfa-1（次要）菌毛和41 kDa fimA（主要）菌毛。我们发表的研究表明牙龈卟啉单胞菌的次要菌毛靶向C型凝集素受体DC特异性ICAM-抓取非整联蛋白（DC-SIGN），以进入DC。牙龈卟啉单胞菌被大量带入尚未鉴定的富含DC-SIGN的细胞内区室，其中牙龈卟啉单胞菌看起来基本上是完整的和有活力的。此外，次要菌毛在DC中诱导免疫抑制性细胞因子和共刺激分子谱，并且DC诱导Th 2效应子应答。我们现在已经纯化了天然的次要菌毛，它似乎是糖基化的，并形成菌毛样200 nm的链，通过电子显微镜显示。牙龈卟啉单胞菌的主要菌毛也促进其进入DC，但DC-SIGN不参与。这些DC产生高水平的IL-12 p70、IL-23和IL-6，并诱导强烈的CD 4+幼稚T细胞增殖。应答主要菌毛的T细胞似乎是Th 17细胞：分泌IL-17和IFN 3。因此，该更新申请的目的是确定牙龈卟啉单胞菌的次要和主要菌毛在人DC内牙龈卟啉单胞菌的细胞内命运中的作用（目的1）、牙龈卟啉单胞菌激活的DC中的信号传导途径（目的2）和牙龈卟啉单胞菌在DC中引发的T细胞效应子应答（目的3）。这些持续研究的总体目标是确定这种口腔粘膜病原体如何能够在DC中持续存在并调节DC介导的免疫应答的机制。 公共卫生相关性：牙龈疾病或牙周病是牙齿支持组织的疾病，导致早期牙齿脱落，并与心脏病或中风的风险增加有关。我们不明白为什么牙周病如此难以成功治疗。它似乎是一种终身感染，如艾滋病或在某些情况下肺结核。我们认为这可能是由于细菌牙龈卟啉单胞菌感染牙龈并逃避或抑制免疫系统的能力。我们的研究结果表明，它通过在白色血细胞树突细胞中存活并抑制其免疫功能来实现这一点。本申请的目的是确定该物种如何能够在树突状细胞中持续存在并抑制其功能。

DESCRIPTION (provided by applicant): While part of a complex biofilm, P. gingivalis is uniquely able to infect the submucosal regions of the human oral mucosa whereupon it associates in situ with the potent antigen presenting cells dendritic cells (DCs) in CP. These DCs form organized immune conjugates with CD4+ T cells, called oral lymphoid foci or OLF. The immunomodulatory functions of DCs in response to P. gingivalis infection is thus of intense interest in our laboratory. P. gingivalis expresses an unusual immunomodulatory LPS and two fimbrial adhesins: the 67 kDa mfa-1 (minor) fimbriae and the 41 kDa fimA (major) fimbriae. Our published studies indicate that the minor fimbriae of P. gingivalis targets the C-type lectin receptor DC- specific ICAM-grabbing non-integrin (DC-SIGN), for entry into DCs. P. gingivalis is taken into as yet unidentified DC-SIGN-rich intracellular compartments in large numbers, where P. gingivalis appear essentially intact and viable. Moreover, the minor fimbriae induce an immunosuppressive cytokine and costimulatory molecule profile in DCs and the DCs induce a Th2 effector response. We have now purified the native minor fimbriae and it appears to be glycosylated and forms fimbrial-like 200 nm strands, revealed by electron microscopy. The major fimbriae also enhance entry of P. gingivalis into DCs, but DC-SIGN is not involved. These DCs produce high levels of IL-12p70, IL-23 and IL-6 and induce strong CD4+ naive T cell proliferation. The T cells in response to major fimbriae appear to be Th17 cells: secreting IL-17 and IFN3. The objectives of this renewal application therefore are to determine the roles of minor and major fimbriae of P. gingivalis in the intracellular fate of P. gingivalis within human DCs (Aim 1), the signaling pathways in DCs activated by P. gingivalis (Aim 2) and the T cell effector responses elicited in DCs by P. gingivalis (Aim 3). The overall goal of these continuing studies is to identify the mechanisms for how this oral mucosal pathogen is able to persist in DCs and modulate DC-mediated immune responses. PUBLIC HEALTH RELEVANCE: Gum disease or periodontal disease is a disease of the supporting tissues of the teeth that results in early tooth loss and has been linked to increased risk for heart disease or stroke. We do not understand why periodontal disease is so difficult to treat successfully. It seems to be a lifelong infection like AIDS or in some cases tuberculosis. We think that this may be due to the ability of the bacterial species Porphyromonas gingivalis to infect the gums and evade or suppress the immune system. Our results suggest it does this by surviving within the white blood cells dendritic cells and suppressing their immune functions. The purpose of this application is to determine how this species is able to persist in dendritic cells and suppress their functions.