IFN Immune Effector Mechanisms in Cerebral Toxoplasmosis

描述（由申请方提供）：弓形虫是一种普遍存在的细胞内原生动物寄生虫，是免疫功能低下个体的主要机会性感染，是新生儿先天性弓形虫病的原因，最近已被确定为潜在的生物恐怖主义因子（列表B）。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。大脑中的弓形虫研究者先前的研究确定IFN γ显著抑制T细胞复制。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，研究者最近确定，IFN γ介导的星形胶质细胞抑制在GTP结合蛋白，GTP（deltaGTP）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。这项建议的具体目标是：1）鉴定野生型和IGTP敲除中的IFN γ应答基因（deltaIGTP）星形胶质细胞，2）表征IFNgamma对星形胶质细胞中寄生虫液泡建立的影响; 3）调查IFNgamma抑制是通过影响囊泡运输和/或介导的假设或胆固醇运输到寄生虫液泡，并且IGTP参与调节这种运输。

DESCRIPTION (provided by the applicant): Toxoplasma gondii is a ubiquitous intracellular protozoan parasite that is a major opportunistic infection in immunocompromised individuals, the cause of congenital toxoplasmosis in newborns and recently has been identified as a potential bioterrorism agent (list B). Cytokines play an important role in the regulation of T. gondii in the central nervous system. Interferon-gamma (IFN() is the main cytokine controlling replication of T. gondii in the brain. The investigator's previous studies defined that IFNgamma 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, the investigator recently determined that IFNgamma mediated inhibition in astrocytes was reversed in astrocytes deficient in the GTP binding protein, IGTP (deltaIGTP). 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) Identify the IFNgamma response genes in wild type and IGTP knockout (deltaIGTP) astrocytes via microarray analysis, 2) Characterize the effect of IFNgamma on the establishment of the parasitophorous vacuole in astrocytes and 3) Investigate the hypothesis that IFNgamma inhibition is mediated by affecting vesicular trafficking and/or cholesterol trafficking to the parasitophorous vacuole and that IGTP is involved in regulating this trafficking.