Immune Regulation In Toxoplasmosis And Other Opportunist

弓形虫病和其他机会性疾病的免疫调节

• 批准号: 6985869
• 负责人: Alan Sher
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6985869
• 关键词: Toxoplasma gondii; chemokine receptor; dendritic cells; eicosanoids; enzyme linked immunosorbent assay; host organism interaction; human immunodeficiency virus 1; immunoregulation; interleukin 12; laboratory mouse; mass spectrometry; microorganism immunology; protein purification; proteomics; recombinant proteins; tissue /cell culture; toxoplasmosis

Dendritic cell (DC) production of IL-12 is thought to be a major initiation step in host resistance to Toxoplasma gondii. However, over-production of this cytokine can be detrimental to the host resulting in severe tissue damage. Lipoxin A4 (LXA4) is a potent endogenous lipoxygenase-derived eicosanoid with antiinflammatory and proresolving properties. We have previously shown that supraphysiological levels of LXA4 are generated during T. gondii infection, which in turn reduces interleukin (IL) 12 production by dendritic cells, thus dampening Th1-type cell-mediated immune responses and host immunopathology. In this years work, we investigated the mechanism by which T. gondii's stimulates LXA4 biosynthesis. Proteomic analysis of T. gondii extract (soluble tachyzoite antigen [STAg]), which preserves the immunosuppressive and antiinflammatory activity of the parasite, yielded several peptide matches to known plant lipoxygenases. To investigate their potential enzymatic function, we incubated STAg with arachidonic acid and found using LC-UV-MS-MS?based lipidomics that the parasite extract generated the production of both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase(15-LO)activity. In addition, T. gondii tachyzoites (the rapidly multiplying and invasive stage of the parasite) generated LXA4 when provided with exogenous arachidonic acid. Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties. Importantly, administration of a plant 15-lipoxygenase generated endogenous LXA4 and mimicked the suppression of IL-12 production by splenic dendritic cells observed after T. gondii infection or STAg administration. These findings suggest that T.gondii stimulates LXA4 production by augmenting 15-lipoxygenase levels in the host through its own sythesis of the enzyme. On a broader level our studies indicate that enzymes involved in eicosonoid synthesis expressed by a pathogen can interact with host biosynthetic circuits to generate lipoxins that act as endogenous "stop signals" suppressing the host immune response and limiting acute inflammation.

IL-12的树突状细胞（DC）的产生被认为是宿主对弓形虫弓形虫的抗性的主要起始步骤。但是，这种细胞因子的过量产生可能会损害宿主，从而导致严重的组织损伤。 Lipoxin A4（LXA4）是一种有效的内源性脂氧合酶衍生的eicosanoid，具有抗炎和预溶性。我们先前已经表明，LXA4的Xapipyology水平是在T. gondii感染过程中产生的，进而降低了树突状细胞的白介素（IL）12产生，从而抑制了Th1型细胞介导的免疫反应和宿主免疫病理学。在这几年的工作中，我们研究了T. gondii刺激LXA4生物合成的机制。 T. gondii提取物的蛋白质组学分析（可溶性tachyzoite抗原[stag]），该抗原保留了寄生虫的免疫抑制和抗炎活性，可与已知的植物Lipoxygoxygenase产生多种肽匹配。为了研究其潜在的酶促功能，我们与花生四烯酸一起孵育雄鹿，并使用LC-UV-MS-MS？基于基于LIPIDOMIS的脂质组学发现寄生虫提取物产生了15-HETE和5,15-dihete的产生，这表明T. gondii携带15-脂氧合酶（15-lo）活性。另外，寄生虫的Gondii速二菌（寄生虫的迅速繁殖和侵入性阶段）在配备外源性蛛网膜酸时会产生LXA4。植物（大豆）脂氧合酶本身的局部给药自身降低了鼠腹膜炎中的嗜中性粒细胞性浸润，表明15-脂氧酶具有抗炎特性。重要的是，施用植物15-脂氧合酶产生的内源性LXA4，并模仿gondii感染或Stag给药后观察到的脾树突状细胞对IL-12产生的抑制。这些发现表明，T.gondii通过其自身的酶学酶在宿主中提高15加氧化氢酶水平来刺激LXA4的产生。在更广泛的层面上，我们的研究表明，与病原体表达的类eicosonoid合成的酶可以与宿主的生物合成回路相互作用，以产生脂蛋白，这些脂蛋白充当内源性“停止信号”抑制宿主免疫反应并限制急性炎症。