ROLE OF OSTEOPONTIN IN GRANULOMATOUS INFLAMMATION

肉芽肿形成背后的关键调节事件，特别是肉芽肿基质的作用尚不清楚。我们最近证实了早期T细胞激活基因Eta-1(也称为骨桥蛋白，一种骨基质酸性糖蛋白)存在于结核样结节病的活动性肉芽肿皮损中。我们的初步数据表明，Eta-1/OPN在体外对T淋巴细胞是一种有效的趋化、粘附素和增殖共刺激剂。这些数据，体内宿主对立克次体等病原体反应缺陷的小鼠骨桥蛋白减少，以及骨桥蛋白对单核细胞和巨噬细胞具有强大的趋化性，这一事实表明Eta-1/OPN代表了一类新的含有RGD的细胞因子，它调节T细胞和巨噬细胞的功能，在(肺)肉芽肿性炎症的启动和维持中发挥关键作用。具体地说，我们假设巨噬细胞、淋巴细胞、内皮和上皮细胞表达Eta-1/OPN是肉芽肿形成的早期和重要事件，它调节炎症细胞的运输、细胞激活和细胞因子的产生、增殖和细胞死亡。这项拨款建议阐明它的免疫功能，并研究它在肉芽肿形成中的作用。体外研究包括免疫细胞和肺细胞产生Eta-1/OPN的特征，以及这些细胞产生的磷酸化和糖基化变体。我们将研究纯化和重组OPN对T细胞功能的影响。将进行体内研究，以确定Eta-1/OPN在肺肉芽肿形成中的作用。将使用一种模型，其中肉芽肿是通过栓塞含有抗原的琼脂糖珠来诱导的，该抗原依赖于Th1和Th2细胞因子而诱导肉芽肿的形成。该模型将应用于基因工程Eta-1/OPN缺陷小鼠和野生型对照。

The key regulatory events behind granuloma formation and particularly the role of the granuloma matrix are not well understood. We have recently demonstrated the presence of the early T-cell activation gene Eta-1 (also known as osteopontin {OPN}, a bone matrix acidic glycoprotein) in active granulomatous lesions of tuberculosis rid sarcoidosis. Our preliminary data demonstrate that Eta-1/OPN is a potent chemoattractant, adhesin and proliferative co-stimulant for T lymphocytes in vitro. These data, the association of reduced osteopontin in mice with defective host response to intracellular pathogens such as Rickettsia tsutsugamushi in vivo, and the fact that steopontin is a potent chemoattractant for monocytes and macrophages suggest that Eta-1/OPN represents a new class of RGD-containing cytokine which regulates T cell and macrophage function, serving a key role in the initiation and maintenance of (lung) granulomatous inflammation. Specifically, we hypothesize that the expression of Eta-1/OPN by macrophages, lymphocytes, endothelial and epithelial cells is an early and important event in granuloma formation which regulates inflammatory cell traffic, cellular activation and cytokine production, proliferation, and cell death. This grant proposes to elucidate its immunologic functions and study its role in granuloma formation. In vitro studies include characterizing the production of Eta-1/OPN by immune cells and lung cells and the phosphorylation and glycosylation variants produced by these cells. The effects on T cell function of purified and recombinant OPN will be studied. In vivo studies will be performed to determine the role of Eta-1/OPN in the formation of granulomas in he lung. A model will be used in which granulomas are induced by the embolization of sepharose beads containing antigens which induce the formation of granulomas dependent on Th1 and Th2 cytokines. The model will be applied to a genetically engineered Eta-1/OPN deficient mouse and wild type controls.