Molecular Mechanisms of Sleep Responses to Viral Infection

描述(申请人提供)：流感病毒诱导的脑调节急性时相反应(APR)包括非快速眼动睡眠(NREMS)持续时间延长。这些反应的分子途径以及所涉及的大脑解剖途径仍处于研究之中。虽然PR8流感病毒被认为是非嗜神经性的，但最近我们发现，在鼻内攻击时，病毒定位于嗅球(OB)并至少经历部分复制，阳性病毒RNA在OB中的表达证明了这一点，并上调了OB和下丘脑(HT)细胞因子的表达。我们研究了这样的假设，即OB-HT途径通过涉及OB中病原体模式识别受体的分子步骤来调节APR，它们诱导白介素1(IL1)相关分子在OB中。 OB、HT和HTIL1/GHRH的作用机制。初步数据：a)鉴定了可抑制APRs的脑特异性IL1受体辅助蛋白(Acpb)；b)提供了仅在神经元上表达IL1I型受体(ILRI)的转基因小鼠；c)表明缺乏GHRH受体的小鼠在病毒攻击后睡眠更少；以前我们证明了GABA能的HT神经元对IL1和GHRH都能接受。我们提出了三个目标来阐明OB-HT通路在APR睡眠反应中的作用。目的1验证AcPb减弱APR-IL1和睡眠对病毒攻击反应的假说。目的2验证PR-8启动APR睡眠反应依赖于ILRI的OB胶质细胞表达的假说。目的3验证这一假设，即HT-GHRH/GHRH受体机制对APR中流感启动的睡眠成分至关重要。我们开发了一种动物模型，首次允许确定大脑特异性细胞因子信号机制AcPb在神经免疫炎症过程中的作用。我们描述了在病毒诱导的APR睡眠反应中，ILRI在神经元和胶质细胞上的表达的相对贡献。我们利用自发突变导致GHRH受体不起作用的小鼠来阐述OB-HT细胞因子/GHRH导致APR睡眠反应的机制。预期的结果将是OB参与启动APR的特征，从而为药物治疗提供了一个新的容易获得的目标，从而为基础研究迅速转化为临床提供了一个新的目标。 公共卫生相关性：这些研究确定了由流感病毒诱导的嗅球中发生的分子机制，该分子机制负责病毒诱导的包括睡眠在内的急性时相反应。我们研究了一种大脑特有的细胞因子适配蛋白，称为白细胞介素1受体辅助蛋白(AcPb)，在疾病行为的大脑调节中的作用。我们还研究了神经元和神经胶质细胞在这一过程中所扮演的特定角色。此外，我们通过表征生长激素释放激素受体在流感睡眠反应中的作用，将发生在嗅球中的分子事件与下丘脑联系起来。预期结果将使基础科学迅速转化为临床；鼻腔应用阿昔洛韦减轻脑部调节的细胞因子风暴。

DESCRIPTION (provided by applicant): Influenza virus-induced brain-regulated acute phase responses (APR) include enhanced duration of non-rapid eye movement sleep (NREMS). The molecular pathways for these responses remain under investigated as do the brain anatomical pathways involved. Although influenza PR8 virus is considered non-neurotropic, recently we showed that upon intranasal challenge the virus localizes to the olfactory bulb (OB) and undergoes at least partial replication, as evidenced by expression of positive sense viral RNA in the OB, and up-regulates OB and hypothalamic (HT) cytokine expression. We investigate the hypothesis that the OB-HT pathway modulates the APR via molecular steps involving pathogen pattern recognition receptors in the OB, their induction of interleukin-1(IL1)-related molecules in the OB and HT and HT IL1/growth hormone releasing hormone (GHRH) mechanisms. Preliminary data; a) characterize a brain-specific IL1 receptor accessory protein (AcPb) that attenuates APRs, b) present a transgenic mouse expressing the IL1 type I receptor (ILRI) only on neurons, and c) show that mice lacking the GHRH receptor sleep less after viral challenge unlike any other mouse; previously we showed that GABAergic HT-neurons are receptive for both IL1 and GHRH. We propose three aims that will clarify the role of the OB-HT pathway in APR sleep responses. Aim 1 tests the hypothesis that AcPb attenuates the APR-IL1 and sleep responses to viral challenge. Aim 2 tests the hypothesis that PR-8- initiation of the APR sleep response is dependent upon OB glial expression of the ILRI. Aim 3 tests the hypothesis that HT-GHRH/GHRH receptor mechanisms are critical to the flu-initiated sleep component of the APR. We develop an animal model that for the first time allows determination of the role of a brain-specific cytokine signaling mechanism, AcPb, in neuro-immune inflammatory processes. We characterize the relative contribution of the ILRI expression on neurons vs. glia in the APR sleep responses induced by virus. We make use of mice with a spontaneous mutation resulting in non-functional GHRH receptors to elaborate the OB-HT cytokine/GHRH mechanisms leading to APR sleep responses. Anticipated results will characterize OB involvement in the initiation of the APR and thereby provide a new readily accessible target for drug therapy and thus for the rapid translation of basic research to the clinic. PUBLIC HEALTH RELEVANCE: These studies determine molecular mechanisms occurring in the olfactory bulb induced by influenza virus that are responsible for the viral-induced acute phase response including sleep. We examine the role of a brain- specific cytokine adaptor protein, called interleukin-1 receptor accessory protein (AcPb), in the brain regulation of sickness behavior. We also examine the specific roles neurons and glia play in this process. Further, we link the molecular events occurring in the olfactory bulb to the hypothalamus by characterizing the role the growth hormone releasing hormone receptor in sleep responses to influenza. Expected results will allow for the rapid translation of basic science to the clinic; e.. nasal application of AcPb to attenuate brain-regulated aspects of the cytokine storm.