Antimicrobial Peptides and Innate Immunity in Otitis Media

描述(由申请人提供)：先天免疫在维护中耳健康方面发挥着积极作用，在中耳炎(OM)期间也发挥着积极作用。抗菌肽(AP)是先天性免疫系统的关键成分，在呼吸道、胃肠道和泌尿生殖道的巨大上皮表面提供第一线的微生物灭活作用。这些阳离子多肽具有强大的抗菌活性，可以是相加的，通常是协同作用的，提供了天然免疫系统的高效作用机制。然而，现在很清楚的是，AP不仅仅是抗微生物的，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，AP在调节获得性免疫反应中发挥着关键作用。最近，人们也开始意识到，生活在粘膜表面的共生微生物刺激上皮细胞产生AP，从而有助于宿主维持防御性粘膜屏障和动态平衡。后一点与我们的更新应用特别相关，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子集引起的。然而，当宿主的呼吸道防御受到损害时，最典型的是上呼吸道(URT)病毒，这些细菌可能会表现为机会性病原体，并进入现在防御不力的中耳，这种情况与肠道的情况密切相关，在这种情况下，正常微生物群和排列在胃肠道的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期间共同进化为和谐共存(事实上，这些微生物可能如何帮助塑造最上面呼吸道的先天免疫系统，反之亦然)对于我们能够理解OM病程早期发生了什么问题，以及是什么允许恢复到稳态和健康是至关重要的。因此，继续研究包括鼻咽癌、咽鼓管和中耳在内的最上呼吸道的固有免疫系统是很重要的。为此，我们建议研究先天性免疫在以下方面的作用：1)在非分型流感嗜血杆菌(NTHI)和NP的粘膜上皮之间发生的分子串扰水平上的健康(即在定植期间)；2)多菌疾病OM(即“正常”OM)，特别关注URT病毒诱导的固有免疫效应因子的异常表达和树突状细胞功能改变(S)如何在疾病过程中起作用；3)OM病的极端--倾向性和慢性化，特别关注编码α-和β-防御素家族成员的基因的拷贝数变化如何影响倾向性。我们还将研究AP最初如何通过诱导NTHI形成生物膜而不经意地导致慢性化，但随后参与其分解，并4利用我们对最上面呼吸道的先天免疫的增强了解来开发治疗和/或预防OM的新方法。公共卫生相关性：由于治疗和/或预防中耳炎(OM)的改进方法的持续需要，对侵入性更小、更有针对性的儿科疫苗的渴望，以及认识到我们对急性和慢性OM的微生物学和免疫学的了解是不完整的，我们迫切需要更多地了解身体如何保护最上层的呼吸道，并确定和进一步开发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。获得这一更好的理解将可能使我们能够开发出局部受限和特定部位的治疗方法，并促进疫苗配方的改进，以提高其疗效。这些方法可以极大地增加我们对抗急性和慢性OM的现有武器库，重要的是，可能提供一种机制，在疾病过程的非常早期状态--NP的定植--进行干预，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.