Antimicrobial Peptides and Innate Immunity in Otitis Media

描述（由申请人提供）：先天免疫在维持中耳健康方面发挥着积极作用，并且在中耳炎（OM）期间也积极参与。抗菌肽（APs）是先天免疫系统的关键组成部分，为呼吸道、胃肠道和泌尿生殖道上皮表面的微生物提供一线失活。这些阳离子多肽的有效抗菌活性，可以是相加的，通常是协同的，提供了先天免疫系统的高度有效的作用机制。然而，现在清楚的是，APs不仅仅具有抗菌作用，事实上，杀死微生物甚至可能不是它们最主要的功能，相反，越来越多的证据表明APs在调节获得性免疫反应中起着关键作用。最近，人们也开始认识到，生活在粘膜表面的共生微生物刺激上皮细胞产生APs，从而有助于宿主维持防御性粘膜屏障和体内平衡。后一点与我们的续期申请特别相关，因为OM不是由高毒力微生物引起的；相反，OM是由组成儿童鼻咽（NP）正常菌群的共生细菌的一个子集引起的。然而，当宿主气道防御被破坏时，最典型的是上呼吸道（URT）病毒，这些细菌可以作为机会性病原体，进入现在防御薄弱的中耳，这种情况与肠道非常相似，其中正常微生物群和胃肠道上皮细胞之间发生的分子串扰已经得到了很好的研究。了解宿主和微生物如何在定植过程中共同进化和谐共存（事实上，这些微生物如何可能帮助塑造最上层气道的先天免疫系统，反之亦然），对于我们能够理解在OM疾病过程的早期出现“问题”，以及什么允许恢复体内平衡和健康至关重要。因此，继续研究包括NP、耳咽管和中耳在内的上气道先天免疫系统具有重要意义。为了实现这一目标，我们建议研究先天免疫在以下方面的作用：1)在不可分型流感嗜血杆菌（NTHI）和NP粘膜上皮之间发生的分子串扰水平上的健康（即定植期间）；2)多微生物病OM(即：“正常”OM)，特别关注URT病毒诱导的先天免疫效应物表达失调和树突状细胞功能改变如何促进疾病过程；3) OM疾病的极端易感性和慢性，特别关注编码α -防御素和β -防御素家族成员的基因拷贝数变化如何促进易感性。我们还将研究ap如何首先通过诱导NTHI形成生物膜而无意中促成慢性，但后来参与其解决，并利用我们对上气道先天免疫的增强理解来开发治疗和/或预防OM的新方法。公共卫生相关性：由于持续需要改进治疗和/或预防中耳炎（OM）的方法，对侵入性更小、更有针对性的儿科疫苗的渴望，以及我们对急性和慢性OM的微生物学和免疫学的了解尚不完整，我们迫切需要寻求对身体如何保护最上层气道的更深入了解。并确定和进一步发展潜在增强这些防御机制的方法，作为治疗和/或预防OM的新方法。获得这种更好的理解将有可能使我们开发出局部受限和特定部位的治疗方法，并促进改进疫苗配方，以提高其效力。这些方法可以极大地增加我们对抗急性和慢性OM的可用武器库，重要的是，可以潜在地提供一种机制，在疾病过程的早期状态进行干预- NP的定植，从而显著降低与这种高度流行的儿科疾病相关的发病率。

DESCRIPTION (provided by applicant): It has become evident that innate immunity plays an active role in maintenance of the health of the middle ear, and is also actively engaged during otitis media (OM). Antimicrobial peptides (APs) are key components of the innate immune system, providing first-line inactivation of microbes on the vast epithelial surfaces that line the respiratory, gastrointestinal and urogenital tracts. The potent antimicrobial activity of these cationic polypeptides, can be additive and is often synergistic, providing the highly effective mechanism of action of the innate immune system. It is now clear however, that APs are not simply antimicrobial, and in fact, microbial killing may not even be their most primary function, rather there is increasing evidence of the pivotal role of APs in regulation of the acquired immune response. Recently, it has also begun to be appreciated that the commensal microorganisms living on mucosal surfaces stimulate epithelial cells to produce APs, and thus contribute to host maintenance of defensive mucosal barriers and homeostasis. This latter point is particularly relevant to our renewal application, because OM is not caused by highly virulent microorganisms; OM is instead caused by a subset of the commensal bacteria that comprise the normal flora of the pediatric naso- pharynx (NP). However, when host airway defenses are compromised, most typically by upper respiratory tract (URT) viruses, these bacteria can behave as opportunistic pathogens and gain access to the now poorly defended middle ear, a situation that closely parallels that of the gut, wherein the molecular crosstalk that occurs between the normal microbiota and the epithelial cells that line the gastrointestinal tract has been well- studied. Understanding how host and microbe have co-evolved to exist in harmony during colonization (and in fact, how these microbes have likely helped to shape the innate immune system of the uppermost airway and vice versa) is essential to our then being able to understand what goes `wrong' early in the disease course of OM, as well as what allows return to homeostasis and health. It is thereby important to continue to study the innate immune system of the uppermost airway, which includes the NP, Eustachian tube and middle ear. Toward this goal, we propose to investigate the role of innate immunity in: 1) health (i.e. during colonization) at the level of the molecular crosstalk that occurs between nontypeable Haemophilus influenzae (NTHI) and the mucosal epithelium of the NP; 2) the polymicrobial disease OM (i.e. `normal' OM), with a particular focus on how dysregulated expression of effectors of innate immunity and altered dendritic cell function(s) induced by the URT viruses contributes to the disease process; 3) the OM disease extremes - proneness and chronicity, with a particular focus on how copy number variations in genes that encode alpha- and beta-defensin family members contribute to proneness. We will also study how APs might first inadvertently contribute to chronicity by inducing NTHI to form a biofilm, but later participate in its resolution and 4 to utilize our enhanced under- standing of innate immunity in the uppermost airway to develop novel methods to treat and/or prevent OM. PUBLIC HEALTH RELEVANCE: Due to the continuing need for improved methods to treat and/or prevent otitis media (OM), the desire for less invasive, more targeted pediatric vaccines and the realization that our understanding of both the microbiology and immunology of acute and chronic OM is incomplete, it is imperative that we seek a greater understanding of how the body defends the uppermost airway, and that methods to potentially augment these defense mechanisms be identified and developed further as a novel approach for the treatment and/or prevention of OM. Gaining this improved understanding will potentially allow us to develop therapeutic approaches that are locally restricted and site-specific, as well as facilitate the refinement of vaccine formulations so as to enhance their efficacy. These approaches could add tremendously to our available arsenal for fighting acute and chronic OM and importantly, could potentially provide a mechanism to intervene at a very early state in disease process- colonization of the NP, thereby significantly reducing the morbidity associated with this highly prevalent pediatric disease.