Chemokine-Cytokine Nexus in Fungal Immunity

描述（由申请人提供）：二型真菌，荚膜组织胞浆菌（Hc）是美国中西部和东南部特有的。大多数感染是轻微的或无症状的。该微生物建立潜伏状态，并可在免疫活性或免疫抑制个体中引起危及生命的感染。我们已经表明，趋化因子受体，CCR 2，是至关重要的，在控制肺部感染的HC小鼠。这种受体的缺乏与感染的恶化和非常规来源-巨噬细胞和树突状细胞诱导白细胞介素（IL）-4有关。IL-4的中和恢复免疫力。我们已经获得的证据表明，信号的趋化因子CCL 7和2，两个CCR 2配体，是重要的最佳宿主防御。在下面的建议中，我们将探讨CCR 2信号传导在抑制IL-4产生和促进有效的细胞免疫应答中的重要机制。具体目标1将研究CCL 2和7在宿主防御和炎症中的作用。我们将在原位和体外鉴定产生这些趋化因子的细胞。我们将研究受体或趋化因子的缺乏是否会改变酵母细胞的体内驻留。我们将确定CCR 2配体是否表现出吞噬细胞的直接或间接激活。在具体目标2中，我们将利用具有与IL-4基因连接的绿色荧光蛋白的小鼠来研究IL-4转录细胞的进化和时间外观。将进行研究以确定Hc是否调节CCR 2的表达。我们还将研究巨噬细胞和树突状细胞用于产生IL-4的途径。在具体目标3中，我们将研究CCR 2和/或IL-4的缺乏导致免疫缺陷的机制。我们将评估CCR 2的缺乏促进替代活化的巨噬细胞或髓系抑制细胞出现的可能性。我们将确定这些人群中的一个或两个是否会抑制抗真菌免疫力。我们将测试T细胞的功能和扩展。我们将评估T细胞在肺中扩增失败是主动抑制以及表面受体调节的结果的可能性。这些研究的目的是更好地了解HC的发病机制，从而提高HC如何逃避宿主防御的知识。这些发现有助于趋化因子-细胞因子网络在微生物发病机制中的影响，并表明CCL 7的新作用。

DESCRIPTION (provided by applicant): The dimorphic fungus, Histoplasma capsulatum (Hc) is endemic to the Midwestern and southeastern United States. Most infections are mild or asymptomatic. The organism establishes a latent state and can cause a life-threatening infection in immunocompetent or immunosuppressed individuals. We have shown that the chemokine receptor, CCR2, is critically important in controlling pulmonary infection with Hc in mice. The absence of this receptor is associated with exacerbation of infection and the induction of interleukin (IL)-4 by unconventional sources-macrophages and dendritic cells. Neutralization of IL-4 restores immunity. We have obtained evidence that signaling by the chemokines CCL7 and 2, two CCR2 ligands, are important in optimal host defenses. In the following proposal, we will explore the mechanisms by which CCR2 signaling is important in constraining IL-4 generation and promoting an effective cellular immune response. Specific aim 1 will examine the role of CCL2 and 7 in host defenses and inflammation. We will identify the cells producing these chemokines in situ and ex vivo. We will investigate if the absence of the receptor or the chemokines alters the in vivo residence of yeast cells. We will ascertain if CCR2 ligands manifest a direct or indirect activation of phagocytes. In specific aim 2, we will utilize a mouse that has green fluorescent protein linked to the IL-4 gene to investigate the evolution and temporal appearance of IL-4- transcribing cells. Studies will be performed to determine if Hc modulates expression of CCR2. We also will investigate the pathways that macrophages and dendritic cells utilize to generate IL-4. In specific aim 3, we will examine mechanisms by which the absence of CCR2 and/or IL-4 contributes to defective immunity. We will assess the possibility that the absence of CCR2 promotes the emergence of alternatively activated macrophages or myeloid suppressor cells. We will determine if either or both of these populations dampen antifungal immunity. We will test T cell function and expansion. We will assess the possibility that the failure of T cells to expand in the lungs is consequence of active inhibition as well as modulation of surface receptors. The goal of these studies is to better understand the pathogenesis of Hc, thereby enhancing knowledge of how Hc escapes host defenses. These findings contribute to the influence of the chemokine- cytokine network in microbial pathogenesis and evince a new role for CCL7.