IFN Inhibition of Toxoplasma gondii in Astrocytes

描述（由申请人提供）：弓形虫是一种普遍存在的细胞内原生动物寄生虫，是艾滋病患者和其他免疫功能低下个体的常见感染，也是先天性弓形虫病的病因。在艾滋病患者和其他免疫功能低下的宿主中，感染是由于大脑中潜伏感染的重新激活，导致严重的并且通常是致命的坏死性脑炎。细胞因子在T.中枢神经系统中的弓形虫干扰素-γ（IFN-γ）是控制T细胞复制的主要细胞因子。大脑中的弓形虫我以前的研究确定IFN-γ显著抑制T细胞的复制。星形胶质细胞中的弓形虫。发现星形胶质细胞中IFN γ的机制独立于所有已知的抗弓形虫效应器机制。然而，我们最近确定，干扰素？星形胶质细胞中的介导的抑制在GTP结合蛋白GTP（AIGTP）缺陷的星形胶质细胞中被逆转。IGTP的功能尚不清楚，但认为其参与调节囊泡运输途径。在星形胶质细胞中IFN γ诱导的基因表达的初步微阵列研究表明，在IFN γ处理的星形胶质细胞中宿主细胞胆固醇代谢改变。T.最近已显示弓形虫需要从宿主细胞摄取胆固醇。对脂质和胆固醇运输到寄生虫空泡的影响可能是星形胶质细胞中IFN γ抑制的机制。由于IFN γ依赖性机制在控制T.尽管弓形虫在大脑中的作用机制，但理解这些机制仍然是理解疾病发病机制的重要挑战。在本项目中，将研究IFN γ诱导星形胶质细胞抑制的机制。该提案的具体目的是：1）在野生型与GTP敲除（deltaGTP）星形胶质细胞中进行IFN γ应答基因的微阵列分析，2）研究IFN γ影响囊泡运输至寄生虫空泡（Aim 2A）或IFN γ影响胆固醇运输至寄生虫空泡（Aim 2B）以及GTP参与调节这种运输的假设。

DESCRIPTION (provided by applicant): Toxoplasma gondii is a ubiquitous intracellular protozoan parasite that is a common infection in AIDS patients and other immunocompromised individuals as well as the cause congenital toxoplasmosis. In AIDS patients and other immunocompromised hosts infection is due to reactivation of a latent infection in the brain that results in a severe and often fatal necrotizing encephalitis. Cytokines play an important role in the regulation of T. gondii in the central nervous system. Interferon-gamma (IFNgamma) is the main cytokine controlling replication of T. gondii in the brain. My previous studies defined that IFN-gamma significantly inhibits the replication of T. gondii in astrocytes. The mechanism of IFNgamma in astrocytes was found to be independent of all of the known anti-Toxoplasma effector mechanisms. However, we recently determined that IFN? mediated inhibition in astrocytes was reversed in astrocytes deficient in the GTP binding protein, IGTP (AIGTP). The function of IGTP is not known but it is thought to be involved in regulation of the vesicular trafficking pathway. Preliminary microarray studies of IFNgamma induced gene expression in astrocytes indicate that host cell cholesterol metabolism is altered in IFNgamma treated astrocytes. T. gondii has recently been shown to require cholesterol uptake from the host cell. Effects on lipid and cholesterol trafficking to the parasitophorous vacuole may be the mechanism of IFNgamma inhibition in astrocytes. As IFNgamma dependent mechanism(s) play a major role in controlling T. gondii in the brain, understanding these mechanism(s) remains an important challenge in understanding disease pathogenesis. In this project the mechanism(s) of IFNgamma induced inhibition in astrocytes will be investigated. The specific aims of this proposal are: 1) To perform a microarray analysis of IFNgamma response genes in wildtype vs. IGTP knockout (deltaIGTP) astrocytes and 2) Investigate the hypothesis that IFNgamma affects vesicular trafficking to the parasitophorous vacuole (Aim 2A) or that IFNgamma affects cholesterol trafficking to the parasitophorous vacuole (Aim 2B) and that IGTP is involved in regulating this trafficking .