HIV suppression by Beta-defensins

描述(由申请人提供)：β-防御素是一种小的(3-5KD大小)分泌蛋白，是天然免疫的组成部分；一些是结构性表达的，如人β-防御素(HBD)-1，而另一些，如hBD2和-3，可被细胞因子或其他免疫反应刺激诱导。β-防御素主要由上皮细胞和中性粒细胞分泌，尽管在T和NK细胞中也观察到它们的分泌，最初它们被描述为抗菌蛋白；最近的研究表明，它们也起到趋化作用。它们在口腔、舌头、消化器官的上皮细胞以及呼吸道、乳腺、肝脏和其他器官中的表达水平升高。特别是，唾液中存在着β-防御素，这些蛋白质在口腔中的浓度可能非常高，局部测得的浓度高达100微克/毫升，在舌头100微米厚的一层。因此，β-防御素作为先天免疫的重要组成部分，控制着口腔感染的发生。β-防御素的抗菌活性是由于它们具有透过细菌膜的能力。综上所述，这些信息表明，β-防御素可以提供一种针对口腔艾滋病毒感染的先天免疫，可能被用于抗艾滋病毒预防。我们的初步数据表明，选择的β-防御素，特别是hBD2，以剂量依赖的方式抑制R5艾滋病毒感染，剂量与口腔中测量的剂量相容或更低。此外，我们的研究表明，直接对病毒进行hBD2治疗可以降低HIV感染。这种抗病毒活性让人想起最近报道的阿尔法防御素抑制艾滋病毒的特性。然而，口腔中只有β-防御素以抑制艾滋病毒的浓度自然存在。因此，我们的中心假设是，β-防御素介导和抗逆转录病毒机制，基于抑制病毒进入口腔，能够防止HIV经口传播。 因此，我们建议a)表征hBD2抑制哪些HIV-1表型。这些实验将确定hBD2的广泛抑制作用，以及它在体内的抑制作用机制是否决定了hBD2对HIV-1生命周期事件的影响。在这个目标中，我们将检查和比较hBD2对HIV进入/融合以及对病毒复制的细胞内步骤的影响。 阐明HIV感染和表达受hBD2影响的事件(S)将有助于深入研究其作用机制和结构功能研究，从而为新的抗病毒治疗和预防策略奠定基础。最后，这些研究将有助于理解先天免疫在口腔中的作用。

DESCRIPTION (provided by applicant): beta-Defensins are small (3-5Kd in size) secreted proteins that are components of innate immunity; some are constitutively expressed, such as human beta-defensin (HBD)-1, while others, like hBD2 and -3, are inducible by cytokines or other immune response stimuli. beta-defensins are secreted preeminently by epithelial cells, and by neutrophil cells, although their secretion has been observed also in T and NK cells, and initially they were described as antimicrobial proteins; recent research has indicated that they also act as chemoattractants. Their expression is elevated in the epithelia of the mouth, tongue, digestive apparatus, and also in airways, mammary gland, liver and other organs. In particular, beta-defensins are present in saliva, and the concentration of these proteins can be very high in the oral cavity, with measured local concentration as high as 100mu g/ml, in a 100mu m-thick layer in the tongue. Therefore, it appears that beta-defensins, as important component of the innate imniunity, control the occurrence of infections in the oral cavity. The antimicrobial activity of beta-defensins is due to their ability to permeabilize bacterial membranes. Taken together, this information indicates that beta-defensins could provide a form of innate immunity against oral HIV infection that might be exploited for anti-HIV prophylaxis. In agreement, our preliminary data show that select beta-defensins, especially hBD2, inhibit R5 HIV infection in a dose dependent manner, at doses that are compatible with or below those measured in the oral cavity. In addition, our studies show that hBD2 treatment directly on the virus lowers HIV infection. This antiviral activity is reminiscent of the recently reported HIV suppressive properties of alpha defensins. However, only beta-defensins are naturally present in the oral cavity at HIV-suppressive concentrations. Therefore, our central hypothesis is that beta-defensins mediate and antiretroviral mechanism, based on inhibition of viral entry, in the oral cavity that is capable of preventing oral HIV transmission. Accordingly, we propose to a) characterize which HIV- 1 phenotypes are suppressed by hBD2. These experiments will define the broad suppressive effects of hBD2 and whether its mechanism of suppression functions in vivo b) determine the effects of hBD2 on events in the HIV-1 life cycle. In this aim we will examine and compare the effects of hBD2 on HIV entry/fusion and on intracellular steps of viral replication. The elucidation of the event(s) in HIV infection and expression that are affected by hBD2 will allow for a thorough study of its mechanism of action and for structure-function studies, thus proving basis for novel antiviral therapeutic and preventive strategies. Finally, these studies will constitute a contribution towards the understanding of the role of innate immunity in the oral cavity.