THE CHEMOKINE RECEPTOR CXCR-2 IN ATHEROSCLEROSIS

描述（改编自研究者摘要）：多种机制起作用 以促进巨噬细胞在动脉粥样硬化内膜内的积聚。这 拟议的工作部分源于其他人的观察，包括 在MCP-1受体CCR 2缺陷的apoE敲除小鼠中， 动脉粥样硬化减少，但病变大小和复杂性仍在进展 5-13周。体外单核细胞CCR 2表达也被 几种炎症介质，可以在斑块中，或通过 分化为巨噬细胞。因此，他们建议其他机制 在促进巨噬细胞的保留和扩张中起作用， 动脉粥样硬化病变根据他们以前的工作，他们发现， 内膜巨噬细胞表达趋化因子受体CXCR 2，CXCR 2 配体、GRO α和IL-8。最初的数据还表明， 小鼠CXCR 2同源物mIL-8 RH的缺乏，阻止了早期肿瘤的进展， 巨噬细胞丰富的病变和病变巨噬细胞的保留减少。他们 因此，假设特异性CXCR 2作用介导了病灶内 生长、炎性分化和募集的巨噬细胞的活化。 其具体目标如下： 使用两只动物，定义CXCR 2介导的致动脉粥样硬化事件的顺序， 模型系统他们将首先用骨移植辐射过的LDLR-/-小鼠 来自mIL-8/CXCR 2-/-或对照小鼠的骨髓。小鼠 将喂食普通饲料或高胆固醇饮食，以确定mIL-8 RH在 轻度与重度高胆固醇血症诱导的动脉粥样硬化。第二，评估 mIL-8 RH在白细胞以外的细胞中的作用，他们将研究LDLR-/-， mIL-8 RH-/-小鼠通过杂交获得。早期单核细胞进入，脂肪条纹 在3 - 30岁时，将在两组中研究病变形成和病变进展 周他们将同时检测病变mIL-8 RH和巨噬细胞标志物 包括每组小鼠中的MOMA 2。他们还将比较时间和 巨噬细胞空间聚集、mIL-8 RH、KC/GRO α、JE/MCP-1表达 和CCR 2，oxLDL表位的出现和脂质沉积。 检验CXCR 2表达通过促进巨噬细胞 保留在早期动脉粥样硬化病变，这样做的部分原因是增加 巨噬细胞β 1整合素介导的粘附。首先，他们将确定， LDLR-/-、mIL-8 RH +/+中病变单核细胞的滞留大于LDLR-/-， mIL-8 RH-/-小鼠。为此，他们将分离、标记（使用[3 H]-甘油）和 将骨髓单核细胞输注到高脂肪饮食的LDLR-/-小鼠中。迁移 在主动脉病变中测量标记的单核细胞在体内的滞留 在输注后2、4、7和14天。然后，他们将测试假设， mIL-8 RH-/-引起的巨噬细胞的广义细胞培养粘附缺陷 小鼠与β 1整合素的活化减少有关，β 1整合素结合 纤连蛋白（VLA-4、VLA-5）。他们还将研究CXCR 2介导的对 使用特异性中和的人外周血单核细胞的粘附 整合素和整合素配体的抗体。他们还将测试 巨噬细胞CXCR 2表达是巨噬细胞基质所必需假设 入侵 检验CXCR 2表达通过对巨噬细胞粘附的影响， 介导巨噬细胞分化为独特的促动脉粥样硬化炎性细胞， 表型在这里，他们将进一步研究人类外周单核细胞衍生的 巨噬细胞和小鼠野生型和mIL-8 RH-/-骨髓衍生的巨噬细胞 在CXCR 2在体外正常表达的条件下。他们将 特别是观察CXCR 2配体、GRO α和IL-8对 巨噬细胞增殖和JE/MCP-1表达。他们还将确定 如果CXCCR 2介导的粘附调节apoE的产生，LDL的氧化， 和胆固醇酯的积累。最后根据具体的结果 目的2，他们将测试VLA-5和VLA-4激活的假设，通过 通过CXCR 2配体的刺激，调节这些活性中的一种或多种。他们 还将这些结果与小鼠的特征相关联 特定目标1的动脉粥样硬化病变（即体内相关性研究 CXCR 2表达与PCNA、氧化LDL抗原和清道夫 受体表达）。

DESCRIPTION (Adapted from Investigator's Abstract): Multiple mechanisms operate to promote macrophage accumulation within the atherosclerotic intima. This proposed work stems in part from observations by others, including the finding that in apoE knockout mice which are deficient in the MCP-1 receptor CCR2, atherosclerosis is diminished, but lesion size and complexity still progress from 5-13 weeks. Also monocyte CCR2 expression in vitro is attenuated by several inflammatory mediators which can be in the plaque, or by differentiation to macrophages. They therefore propose that other mechanisms are at play in promoting macrophage retention and expansion within the atherosclerotic lesions. Base on their previous work, they have found that intimal macrophages express the chemokine receptor CXCR2, and the CXCR2 ligands, GROalpha, and IL-8. Initial data also indicate that leukocyte deficiency of the mouse CXCR2 homologue, mIL-8RH, arrested progression of early macrophage-rich lesions and decreased retention of lesion macrophages. They therefore hypothesize that specific CXCR2 effects mediate the intra-lesional growth, inflammatory differentiation and activation of recruited macrophages. Their specific aims are as follows: Define the sequence of atherogenic events mediated by CXCR2, using two animal model systems. They will first transplant irradiated LDLR-/- mice with bone marrow from mIL-8/ CXCR2-/- or control mice under gnotobiotic conditions. Mice will be fed a chow or high cholesterol diet to define the role of mIL-8RH in mild vs. severe hypercholesterolemia-induced atherosclerosis. Second, to assess the role of mIL-8RH in cells other than leukocytes, they will study LDLR-/-, mIL-8RH-/- mice derived by crossbreeding. Early monocyte ingress, fatty streak formation, and lesion progression will be studied in both groups at 3 to 30 weeks. They will concurrently detect lesion mIL-8RH and macrophage markers including MOMA2 in each group of mice. They will also compare temporal and spatial macrophage accumulation, expression of mIL-8RH, KC/GROalpha, JE/MCP-1 and CCR2, the appearance of oxLDL epitopes and lipid deposition. Test the hypothesis that CXCR2 expression acts by promoting macrophage retention in early atherosclerotic lesions, and does so in part by increasing macrophage beta1 integrin-mediated adhesion. First they will determine if retention of lesion monocytes is greater in LDLR-/-, mIL-8RH+/+ than LDLR-/-, mIL-8RH-/- mice. To do so they will isolate, label (using [3H]-glycerol) and infuse bone marrow monocytes into LDLR-/- mice on a high fat diet. Migration and retention of labeled monocytes in vivo will be measured in aortic lesions at 2,4,7, and 14 days post infusion. They will then test the hypothesis that the generalized cell culture adhesion defect of macrophages from mIL-8RH-/- mice is associated with decreased activation of beta1 integrins, which bind fibronectin (VLA-4, VLA-5). They will also study CXCR2-mediated effects on adhesion of human peripheral blood monocytes using specific neutralizing antibodies for integrins and integrin ligands. They will also test the hypothesis that macrophage CXCR2 expression is necessary for macrophage matrix invasion. Test the hypothesis that CXCR2 expression, via effects on macrophage adhesion, mediates macrophage differentiation to a distinct, pro-atherogenic inflammatory phenotype. Here they will further study human peripheral monocyte-derived macrophages and mouse wild type and mIL-8RH-/- bone marrow derived macrophages under conditions where CXCR2 is normally expressed in vitro. They will specifically look at the effects of the CXCR2 ligands, GROalpha, and IL-8 on macrophage proliferation and expression of JE/MCP-1. They will also determine if CXCCR2-mediated adhesion modulates the production of apoE, oxidation of LDL, and accumulation of cholesteryl ester. Finally based on the results of Specific Aim 2, they will test the hypothesis that VLA-5, and VLA-4 activation, via stimulation by CXCR2 ligands, regulate one or more of these activities. They will also correlate these results with the features of the mouse atherosclerotic lesions of Specific Aim 1 (i.e. in vivo correlation studies between CXCR2 expression and PCNA, oxidized LDL antigens, and scavenger receptor expression).