UPR determinants of Brucella virulence

项目总结 布鲁氏菌病仍然是世界上最流行的人畜共患疾病，造成重大的人类发病率和经济损失。 冲击力。目前还不存在安全的人类疫苗。最常与人类疾病有牵连的物种--羊肚菌 已被证明难以根除。在摄入或吸入后，布鲁氏菌会侵入巨噬细胞和其他 吞噬细胞，并在空泡内运输到内质网(ER)，在那里它们建立复制 利基市场。在这个过程中，布鲁氏菌会诱导一种被称为“未折叠蛋白反应”的宿主应激反应。 (普遍定期审议)。UPR通过瞬时减少蛋白质生产和扩张使细胞能够应对内质网应激 急诊室容量。然而，如果内质网应激持续或深入，UPR就会启动细胞凋亡。我们注意到一个 UPR的诱导程度与人类毒力之间存在显著的相关性。与B.bortus和 最强毒力种的疫苗株S19诱导UPR靶标显著上调 小鼠和人巨噬细胞中的基因C/EBP同源蛋白(CHOP)。在某些细菌感染中， 排骨增强了毒力。CHOP对布鲁氏菌小鼠模型中的细胞凋亡和流产起到了关键作用。 CHOP还刺激促炎细胞因子(如IL-23)的产生，从而可能导致人类疾病 表现为脊椎炎等。目前，CHOP在布鲁氏菌感染巨噬细胞和 脊椎炎是未知的，也没有合适的疾病模型来解决这个特定的问题。我们 假设山羊芽孢杆菌诱导更广泛的UPR有助于毒力和 该物种的致病性。为了更好地了解布鲁氏菌与宿主之间的关键相互作用 针对UPR与关节炎的发展，我们提出了以下目标：目标1：验证CHOP假说 通过更多的细菌复制和诱导特定的 宿主炎症反应。我们将确认我们对物种特异性UPR诱导和 通过比较羊出血杆菌和流产出血杆菌诱导的巨噬细胞基因表达来扩展这些结果。 此外，ddit3(CHOP)-/-巨噬细胞将描绘CHOP引起的差异基因表达的部分。 我们将确定CHOP是否调节羊毛虫的细胞凋亡、复制或细胞间传播。最后， 山羊杆菌复制和宿主炎症反应中对CHOP的需求将在体内确定。 目的2：用易感脊柱炎小鼠建立布鲁氏菌脊柱炎模型。 近年来，已经开发出几种需要细胞因子或细胞因子的小鼠脊柱炎模型。 或感染触发物，即SKG-ZAP-70突变模型和B10.RIII小鼠。我们将对这些进行系统的测试 小鼠建立一种健壮、易处理的布鲁氏菌引起的脊柱炎模型，这将使测试成为可能 我们最重要的假设。越来越多的病原体被认为可以操纵 UPR。这项工作将有助于理解UPR如何调节细菌之间的关系 入侵者、寄主反应和疾病表现。

PROJECT SUMMARY Brucellosis remains the most prevalent zoonosis worldwide, incurring significant human morbidity and economic impact. No safe human vaccine exists. The species most often implicated in human disease, B. melitensis has proven refractory to eradication. Following ingestion or inhalation, Brucella invade macrophages and other phagocytes, and traffic within vacuoles to the endoplasmic reticulum (ER) where they establish a replicative niche. During this process, Brucella induce a host stress response known as the “Unfolded Protein Response” (UPR). The UPR enables cells to cope with ER stress by transiently decreasing protein production and expanding ER capacity. However, if ER stress is prolonged or profound, the UPR initiates apoptosis. We have noted a striking correlation between extent of UPR induction and human virulence. In contrast to B. abortus and the vaccine strain S19, B. melitensis (the most virulent species) induces marked upregulation of the UPR target gene C/EBP homologous protein (CHOP) in murine and human macrophages. In certain bacterial infections, CHOP enhances virulence. CHOP critically contributed to apoptosis and abortion in a Brucella murine model. CHOP also stimulates the production of pro-inflammatory cytokines (e.g. IL-23) that could lead to human disease manifestations such as spondyloarthritis. Currently, the role of CHOP in Brucella infection of macrophages and spondyloarthritis is unknown, and there are no appropriate disease models to address this specific question. We hypothesize that the induction of a more extensive UPR by B. melitensis contributes to the virulence and pathogenicity of this species. To gain a greater understanding of the critical interactions between Brucella, host UPR and the development of arthritis, we propose the following aims: Aim 1: Test the hypothesis that CHOP contributes to the virulence of B. melitensis via greater bacterial replication and induction of specific host inflammatory responses. We will confirm our preliminary findings of species-specific UPR induction and expand upon these results by comparing macrophage gene expression induced by B. melitensis vs. B. abortus. Further, ddit3 (CHOP)-/- macrophages will delineate the portion of differential gene expression due to CHOP. We will determine if CHOP regulates apoptosis, replication or cell-cell spread of B. melitensis. Finally, the requirement for CHOP in B. melitensis replication and host inflammatory responses will be determined in vivo. Aim 2: Establish a mouse model of Brucella spondyloarthritis using spondyloarthritis-susceptible mice. Within recent years, several murine spondyloarthritis models have been developed that require either cytokine or infectious triggers, namely the SKG-ZAP-70 mutant model and B10.RIII mice. We will systematically test these mice strains to establish a robust, tractable model of Brucella-induced spondyloarthritis that will enable testing of our overarching hypothesis. An increasing number of pathogens have been recognized to manipulate the UPR. This work will contribute to the understanding of how the UPR mediates the relationships between bacterial invaders, host responses and disease manifestations.