Project 1

中东呼吸综合征(MERS)和严重急性呼吸综合征(SARS)是 冠状病毒引起的人类呼吸道疾病，病死率高。疾病尤其是 在老年人口中情况严重。在前一个资助期，我们显示了年龄相关的增长 在前列腺素D2(PGD2)和上游磷脂酶A2中，PLA2G2D导致不良 免疫反应和存活率下降。肺部处于慢性炎症状态，导致 持续暴露在环境抗原之下。我们推测，PLA2G2D具有抗- 炎症属性，被上调以对抗这种低级别的炎症，导致延迟 对无害抗原的反应，也对快速复制的病毒，如MERS-CoV和SARS- 盖子。相比之下，髓系细胞上的PGD2受体DP1的遗传缺失似乎会导致 呼吸道树突状细胞激活不良提示PGD2-DP1信号转导通路可能具有促进 感染后早期的炎症性质。我们的中心假设是小脂肪 介质是肺部炎症环境中的主要因素，影响着肺的许多方面。 对MERS冠状病毒、SARS冠状病毒等呼吸道病原体的免疫应答。这一假设将是 具体目的如下：1.确定PLA2G2D上调机制 以及PLA2G2D在1200万只老年小鼠的疫苗反应中的作用。CoV复制包括广泛的 细胞膜重排。在这些重排之间的作用，诱导氧化 应激和PLA2G2D的上调将被研究。2.确定PGD2-DP1的作用 1200万小鼠SARS冠状病毒免疫应答中的信号转导。PGD2-DP1信号的缺失 结果：RDC活性和I型干扰素(IFN-I)表达减弱，炎症体增加 激活。我们的目标是确定炎性小体激活的变化是否是主要的 PGD2-DP1信号缺失或其他因素参与的致病效应。3.确定 小鼠MERS的疾病严重程度是否与年龄有关，以及PGD2和PLA2G2D是否 会导致更糟糕的结果。用我们新培育的hDPP4-Ki小鼠和小鼠适应 对于MERS冠状病毒，我们将确定MERS冠状病毒在小鼠身上是否也会导致一种年龄相关性疾病。 我们还将评估二十烷类化合物表达的变化是否会导致更严重的疾病。 MERS-CoV与SARS-CoV不同，它能有效地感染巨噬细胞。在这个目标中，我们将决定 人和小鼠巨噬细胞的生产性感染是否调节PLA2G2D的表达。

Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS) are coronavirus-induced human respiratory diseases with high case-fatality rates. Disease is especially severe in aged populations. In the previous funding period, we showed that age-dependent increases in prostaglandin D2 (PGD2) and an upstream phospholipase A2, PLA2G2D contributed to poor immune responses and decreased survival. The lung is in a state of chronic inflammation, resulting from continued exposure to environmental antigens. We postulated that PLA2G2D, which has anti- inflammatory properties, is upregulated to counter this low grade inflammation, resulting in delayed responses to innocuous antigens but also to rapidly replicating viruses like MERS-CoV and SARS- CoV. In contrast, genetic absence of DP1, the PGD2 receptor on myeloid cells, appears to result in poor respiratory dendritic cell activation suggesting that PGD2-DP1 signaling may have pro- inflammatory properties at early times after infection. Our central hypothesis is that small lipid mediators are major factors in the inflammatory milieu in the lung, affecting many aspects of the immune response to MERS-CoV, SARS-CoV and other respiratory pathogens. This hypothesis will be approached in the following specific aims: 1. To determine the mechanism of PLA2G2D upregulation and the role of PLA2G2D in vaccine responses in 12m old mice. CoV replication includes extensive cellular membrane rearrangements. The role between these rearrangements, the induction of oxidative stress and the upregulation of PLA2G2D will be investigated. 2. To determine the role of PGD2-DP1 signaling in the immune response to SARS-CoV in 12 m mice. The absence of PGD2-DP1 signaling results in diminished rDC activation and type I IFN (IFN-I) expression and increased inflammasome activation. Our goal is to determine whether changes in inflammasome activation are the major pathogenic effect of absent PGD2-DP1 signaling or if other factors are also involved. 3. To determine whether disease severity in murine MERS is age-dependent and whether PGD2 and PLA2G2D contribute to poorer outcomes. Using our newly developed hDPP4-KI mice and mouse-adapted MERS-CoV, we will determine whether MERS-CoV in mice also causes an age-dependent disease. We will also assess whether changes in eicosanoid expression contribute to more severe disease. MERS-CoV, unlike SARS-CoV, productively infects macrophages. In this aim we will determine whether productive infection of human and murine macrophages modulates PLA2G2D expression.