Oral Pathogens and Dendritic Cell Subsets

描述(申请人提供)：虽然牙龈假单胞菌是复杂生物膜的一部分，但它唯一能够感染人类口腔粘膜下区域，从而与CP中强大的抗原提呈细胞树突状细胞(DC)原位结合。这些树突状细胞与CD4T细胞形成有组织的免疫结合物，称为口腔淋巴样病灶或OLF。因此，树突状细胞在牙龈假单胞菌感染后的免疫调节功能引起了我们实验室的极大兴趣。牙龈假单胞菌表达一种特殊的免疫调节内毒素和两种菌毛粘附素：67 kDa MFA-1(小)菌毛和41 kDa fima(大)菌毛。我们已发表的研究表明，牙龈假单胞菌的微小菌毛针对C型凝集素受体DC特异性的ICAM抓取非整合素(DC-SIGN)，以进入DC。牙龈假单胞菌大量存在于尚未确定的富含DC-SIGN的细胞内，在那里似乎基本上完好无损并具有生存能力。此外，次要菌毛在DC中诱导免疫抑制细胞因子和共刺激分子谱，DC诱导Th2效应反应。我们现在已经纯化了天然的微小菌毛，电子显微镜显示，它似乎是糖基化的，并形成了类似菌毛的200 nm链。主要菌毛也促进牙龈假单胞菌进入DC，但DC-SIGN不参与。这些DC产生高水平的IL-12p70、IL-23和IL-6，并诱导强大的CD4初始T细胞增殖。对主要菌毛反应的T细胞似乎是Th17细胞：分泌IL-17和IFN3。因此，这一更新应用的目的是确定牙龈假单胞菌的细菌毛和主要菌毛在人树突状细胞内牙龈假单胞菌的细胞内命运中的作用(目标1)、牙龈假单胞菌激活的树突状细胞中的信号通路(目标2)以及牙龈假单胞菌在树突状细胞中诱导的T细胞效应反应(目标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上持续存在并调节DC介导的免疫反应的机制。 公共卫生相关性：牙周病或牙周病是一种牙齿支持组织的疾病，会导致早期牙齿脱落，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这么难成功治疗。它似乎是一种终生感染，就像艾滋病，或者在某些情况下是结核病。我们认为这可能是由于细菌物种牙龈卟啉单胞菌感染牙龈并逃避或抑制免疫系统的能力。我们的结果表明，它是通过在白细胞内存活并抑制树突状细胞的免疫功能来实现这一点的。这项应用的目的是确定该物种如何能够在树突状细胞中存活并抑制其功能。

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.