Beneficial Effects of Chemokines in Liver

描述（由申请人提供）：趋化因子是具有广泛生物活性的低分子量细胞因子。虽然最初被认为是白细胞趋化剂，但趋化因子现在被认为影响许多生理过程，包括器官发生、肿瘤生长和转移、淋巴细胞运输和伤口愈合。趋化因子控制的两个主要过程是细胞迁移和细胞增殖；然而，肝脏的最新数据表明，趋化因子可以防止急性毒性损伤。趋化因子的细胞保护作用已被认定为一个被称为CXC的肽亚家族。CXC趋化因子的有益特性尚未得到充分的表征。记录CXC趋化因子对肝细胞的有益作用并阐明其作用机制是本提案的主要目标。我们的基本假设是CXC趋化因子抑制肝细胞凋亡。实验设计，以半乳糖胺和内毒素作为模型肝毒素，在体内和细胞培养中表征这种抗凋亡作用。特别重要的是涉及CXCR2 +/+和CXCR2 -/-小鼠骨髓嵌合体的研究，这对于区分趋化因子对体内肝细胞的细胞保护作用及其作为白细胞趋化剂的活性是必要的。在分离肝细胞中的研究旨在通过实时PCR， FACS和趋化因子诱导信号的监测来记录CXC趋化因子受体在肝细胞中的表达。进一步的研究将集中在趋化因子防止细胞凋亡的机制上。迄今为止的研究结果表明，PI-3激酶的激活是这一过程的关键步骤。实验将检测PI-3激酶激活的相关抗凋亡后果，特别是Akt的磷酸化、NF-kappaB的激活和Bcl-xL的上调。总之，拟议的研究将提供CXC趋化因子在肝脏中的活性的全面观点。发现CXC趋化因子的潜在益处至关重要，因为这些化合物的中和被认为是治疗炎症性疾病的一种临床方法。如果趋化因子具有显著的细胞保护作用，那么抗趋化因子治疗可能会因不必要的副作用而复杂化。

DESCRIPTION (provided by applicant): Chemokines are low molecular-weight cytokines with a wide range of biological activities. Although initially characterized as leukocyte chemoattractants, chemokines are now recognized to influence many physiologic processes including organogenesis, tumor growth and metastasis, lymphocyte trafficking and wound healing. The two major processes governed by chemokines are cell migration and cell proliferation; recent data in liver, however, suggest that chemokines protect against acute forms of toxic injury. The cytoprotective role of chemokines has been putatively assigned to one subfamily of peptides designated CXC. The beneficial properties of CXC chemokines have not been fully characterized. Documenting the salutary effects of CXC chemokines toward liver cells and elucidating their mechanism of action are the primary objectives of this proposal. Our fundamental hypothesis is that CXC chemokines inhibit hepatocyte apoptosis. Experiments are designed to characterize this anti-apoptotic effect in vivo and in cell culture, using galactosamine and endotoxin as a model hepatotoxin. Particularly important are studies involving bone marrow chimeras between CXCR2 +/+ and CXCR2 -/- mice, which are necessary to distinguish the cytoprotective effects of chemokines toward hepatocytes in vivo from their activity as leukocyte chemoattractants. Studies in isolated hepatocytes are intended to document CXC chemokine receptor expression in hepatocytes, using real-time PCR, FACS, and monitoring of chemokine-induced signaling. Additional studies will focus on the mechanism by which chemokines prevent apoptosis. Findings to date point to activation of PI-3 kinase as a critical step in this process. Experiments will examine relevant antiapoptotic consequences of PI-3 kinase activation, specifically phosphorylation of Akt, activation of NF-kappaB, and up-regulation of Bcl-xL. In sum, the proposed studies will provide a comprehensive view of the activity of CXC chemokines in liver. Uncovering a potential benefit of CXC chemokines is of critical importance, because neutralization of these compounds is being considered as a clinical approach to inflammatory diseases. If chemokines have significant cytoprotective effects, then anti-chemokine therapy may be complicated by unwanted side effects.