REGULATION OF VCAM-1 EXPRESSION BY INTERLEUKIN 4

炎性细胞的浸润似乎是许多 哮喘气道的病理变化。 循环炎性细胞与内皮细胞的粘附， 这是将这些细胞募集到肺部的第一步。 血管细胞粘附分子-1（VCAM-1）出现在肺组织 哮喘患者的内皮细胞和募集循环嗜酸性粒细胞， 通过与α 4 β 1的相互作用， 这些细胞表面的α 4 β 7整合素。之一 细胞因子在哮喘患者中增加， 气道是IL-4。有证据表明，IL-4是遗传性的。 与过敏性哮喘有关，并在小鼠中敲除IL-4基因 或添加抗IL-4抗体防止显著的 肺部对变应原攻击的炎症反应， 这表明这种细胞因子对于有效的 过敏性炎症反应其他细胞因子，如肿瘤 坏死因子-α（TNF）和IL-1也增加， 哮喘患者我们发现这些细胞因子沿着IL-4 在选择性和协同诱导 人肺微血管内皮细胞VCAM-1的表达 细胞TNF和IL-1引起VCAM-1的转录激活 基因通过启动子中的kappaB位点，而IL-4稳定 由此产生的信息导致协同增加， VCAM-1的表达和VCAM-1在血管内皮细胞上的长时间出现， 内皮表面总之，这些结果表明 IL-4在选择性增加VCAM-1中起重要作用 导致嗜酸性粒细胞和淋巴细胞募集的表达 到肺部 我们已经发现IL-4增加VCAM-1 mRNA， 通过一种新的机制，不涉及 IL-4信号转导的传统JAK/STAT途径。 因此，我们建议研究，以检查这种新的信号 途径，并确定导致 稳定VCAM-1 mRNA。这将涉及两个互补的 方法：1）鉴定IL-4的“由内而外”方法 调节VCAM-1 mRNA的应答性胞质蛋白 稳定性，并使用这种蛋白质来发现细胞质 导致回到IL-4受体的相互作用; 2）“由外向内” 从IL-4受体开始， 调节VCAM-1 mRNA的应答性胞质靶蛋白 稳定提供IL-4与细胞凋亡之间的功能联系的证据， 和VCAM-1的表达和炎症细胞的募集， 在体内，我们将VCAM-1的表达与浸润相关， 炎症细胞进入小鼠肺部以应对过敏原 在野生型和IL-4基因敲除小鼠中进行攻击。作为 如上所述，VCAM-1、IL-1、TNF和IL-4的表达具有 在哮喘患者中会增加。我们建议扩大 这些研究通过将VCAM-1、IL-4和 TNF在空间上和时间上都随着 嗜酸性粒细胞和淋巴细胞的人受试者的气道， 对节段性过敏原激发和撤回吸入的反应 糖皮质激素治疗这些研究将包括过敏和 内源性哮喘嗜酸性粒细胞浸润是 这两个条件。尽管有证据表明IL-4 和VCAM-1在过敏性哮喘中的炎性细胞募集中的作用， 在内源性哮喘中的相应作用的证据仍然需要 待定义。

Infiltration of inflammatory cells appears responsible for many of the pathologic changes that occur in the asthmatic airway. Adhesion of circulating inflammatory cells to the endothelium is the first step in recruitment of these cells to the lung. Vascular cell adhesion molecule-1 (VCAM-1) appears on the lung endothelium in asthmatics and recruits circulating eosinophils and lymphocytes through its interaction with alpha4beta1 and alpha4beta7 integrins on the surface of these cells. One of the cytokines that has been shown to be increased in the asthmatic airway is IL-4. There is some evidence that IL-4 is genetically linked to allergic asthma, and knocking out the IL-4 gene in mice or addition of anti-IL-4 antibody prevents a significant inflammatory response to allergen challenge in the lung, suggesting that this cytokine is critical for an efficient allergic inflammatory response. Other cytokines such as tumor necrosis factor-alpha (TNF) and IL-1 are also increased in asthmatics. We have found that these cytokines along with IL-4 play an important role in selectively and synergistically inducing expression of VCAM-1 on human pulmonary microvascular endothelial cells. TNF and IL-1 cause transcriptional activation of the VCAM-1 gene through kappaB sites in the promoter, whereas IL-4 stabilizes the resulting messages leading to both a synergistic increase in VCAM-1 expression and the prolonged appearance of VCAM-1 on the endothelial surface. Taken together, these results suggest that IL-4 plays an important role in selectively increasing VCAM-1 expression leading to recruitment of eosinophils and lymphocytes to the lung. We have found that IL-4 increases VCAM-1 mRNA stability through a novel mechanism that does not involve the traditional JAK/STAT pathway of IL-4 signal transduction. Therefore, we propose studies to examine this novel signaling pathway and to define molecular events leading to the stabilization of VCAM-1 mRNA. This will involve two complementary approaches: l) an "inside-out" approach to identify an IL-4 responsive cytoplasmic protein(s) that regulates VCAM-l mRNA stability, and to use this protein to discover cytoplasmic interactions leading back to the IL-4 receptor; 2) an "outside-in" approach beginning with the IL-4 receptor and leading to the IL-4 responsive cytoplasmic target protein that regulates VCAM-1 mRNA stability. To provide evidence of the functional link between IL-4 and VCAM-1 expression and recruitment of inflammatory cells in vivo, we will correlate expression of VCAM-1 with the infiltration of inflammatory cells into the mouse lung in response to allergen challenge in both wild-type and IL-4 gene knockout mice. As mentioned above, expression of VCAM-l, IL-I, TNF, and IL-4 have been shown to be increased in asthmatics. We propose to extend these studies by correlating the expression of VCAM-1, IL-4, and TNF both spatially and temporally with the recruitment of eosinophils and lymphocytes to the airway of human subjects in response to segmental allergen-challenge and withdrawal of inhaled glucocorticoid therapy. These studies will include allergic and intrinsic asthmatics. An eosinophil infiltrate is characteristic of both conditions. Although there is evidence of a role for IL-4 and VCAM-1 in inflammatory cell recruitment in allergic asthma, evidence for a corresponding role in intrinsic asthma still needs to be defined.