Consequences of Chemokine-Receptor Interactions: Immune

我们进一步的研究表明，参与天然宿主防御的抗菌肽也与宿主炎症细胞上的受体相互作用，导致获得性免疫反应。人粒细胞衍生防御素对静息的幼稚T细胞和未成熟的树突状细胞具有趋化作用。这些发现的生理学相关性被证明为，当-防御素在疫苗中联合注射时，作为有效的免疫佐剂，即使对来自B细胞淋巴瘤的相对较弱的独特型肿瘤抗原也能增强体液和细胞免疫反应。在由Jacek Lubkowski博士领导的NCI生物物理学家的合作下，上皮细胞衍生的防御素对未成熟的树突状细胞和表达CCR6受体的静止记忆细胞具有趋化作用，被证明具有类似于趋化因子的三级结构。我们实验室的德·杨博士和奥列格·切尔托夫博士扩展了这些发现，表明中性粒细胞和上皮细胞的另一种抗菌产物长春花素(LL37)也可以通过与FPRL-1受体相互作用来动员参与宿主防御的白细胞。此外，C5a、FPRR和FPRL-1等经典的趋化受体在未成熟和成熟的树突状细胞上的表达已被证明进一步了解它们在处理和向T细胞递送抗原以帮助启动免疫反应中的作用。奥列格·切尔托夫博士已经确认，中性粒细胞在脱颗粒过程中释放的组织蛋白酶G是吞噬细胞的趋化剂，如果与抗原一起使用，也是疫苗免疫佐剂。 我们研究了趋化因子在血管生成中的作用及其在肿瘤进展中的作用。Rosalba Salcedo博士指出，与不太成熟的人脐静脉内皮细胞(HUVEC)相比，人微血管内皮细胞(HMVEC)表达更多功能性趋化因子受体。这使她能够证明HMVEC表达功能性CCR2和CCR3以及CXCR1-3，并对趋化因子配体如MCP-1和嗜酸性粒细胞趋化因子起反应。在Matrigel Plug实验中，这些配体还具有体内血管生成活性。 我们以前曾报道，通过与m，d和k阿片受体相互作用，预先暴露于阿片类药物，如内啡肽和吗啡，可以异源脱敏和磷酸化一些趋化因子受体，使它们对这些趋化因子暂时失去反应。在与汤姆·罗杰斯博士的合作中，我们可以证明这是一个双向的过程。预先接触一些趋化因子会导致阿片Mu受体的脱敏和磷酸化。这可能提供了另一种机制，通过抑制阿片信号来加强来自炎症部位的信号。 对NCI国家产品仓库中的中草药成分和具有抗炎作用的植物提取物的分析使我们确定了一些分子实体，这些分子实体抑制了一些促炎趋化因子的趋化活性。鹅去氧胆酸(CDCA)到较小程度的脱氧胆酸(CDA)在无毒浓度下选择性地抑制配体与FPRR和FPRL-1的相互作用。然而，众所周知，这些药物也可以与核受体相互作用，从而抑制细胞因子的产生和免疫反应。因此，这些药物也有抗血管生成的作用，我们正在研究它们对SCID小鼠体内肿瘤生长的影响。 在与印第安纳大学M.Cushman博士的合作中，我们已经证明了Cosalane化合物干扰RANTES与CCR1受体相互作用的能力。这些化合物也有抗血管生成的作用，并在SCID小鼠的人类肿瘤模型上进行了测试。中国抗炎药物中的另一种成分紫草素被发现选择性地干扰CCR1-配体的相互作用。然而，它也通过干扰GPCR启动的信号转导来阻断所有趋化因子的趋化作用。我们目前正在研究这种潜在的有效抗炎和抗血管生成药物的作用机制。

We have further pursued our studies showing that antimicrobial peptides involved in innate host defense also interact with receptors on host inflammatory cells resulting in adaptive immune responses. Human granulocyte derived -defensins are chemotactic for resting naive T cells and immature dendritic cells. The physiological relevance of these findings were documented by showing that the -defensins when coadministered in a vaccine act as potent immunoadjuvant that enhance the humoral as well as cellular immune response even to relatively weak idiotypic tumor antigens from a B cell lymphoma. In collaboration with NCI biophysicists led by Dr. Jacek Lubkowski, the epithelial cell derived -defensins which are chemotactic for immature dendritic cells and resting memory cells that express the CCR6 receptor for "LARC", were shown to have a tertiary structure resembling that of chemokines. Drs. De Yang and Oleg Chertov in our laboratory extended these findings to show that cathelicidin (LL37) another antimicrobial product of both neutrophils and epithelial cells can also mobilize leukocytes engaged in host defense by interacting with the FPRL-1 receptor. Furthermore the expression of classical chemoattractant receptors such as C5a, FPR and FPRL-1 on immature and mature dendritic cells has been demonstrated to further understand their role in the processing and delivery of antigen to T cells to help initiate immune responses. Dr. Oleg Chertov has identified cathepsin G released by neutrophils in the course of degranulation as a chemoattractant of phagocytes and as a vaccine immunoadjuvant if administered together with antigens. We have studied of the role of chemokines in angiogenesis and their contribution to tumor progression. Dr. Rosalba Salcedo showed that human microvascular endothelial cells (HMVEC) express more functional chemokines receptors than the less mature human umbilical vein endothelial cells (HUVEC). This enabled her to show that HMVEC express functional CCR2 and CCR3 as well as CXCR1-3 and react to chemokine ligands such as MCP-1 and Eotaxin. These ligands also have in vivo angiogenic activities in a matrigel plug assay. We previously reported that prior exposure to opiates such as endorphins and morphine by interacting with m,d and k opioid (GPCR) receptors can heterologously desensitize and phosphorylate a number of chemokine receptors, making them temporarily unresponsive to these chemokines. In collaboration with Dr. Tom Rogers we can show that this is a bidirectional process. Prior exposure to a number of chemokines results in the desensitization and phosphoylation of the opioid mu receptor. This may provide another mechanisms by which the pair signals from inflammatory sites are accentuated by suppression of the opioid signals. Analyses of components in Chinese herbal medicines and extracts of plants with purported anti-inflammatory properties available in the National Product Repository of the NCI have led us to identify a number of molecular entities that inhibit the chemotactic activities of a number of proinflammatory chemokines. Chenodeoxycholic acid (CDCA) to a lesser degree deoxyoxycholic acid (CDA) at nontoxic concentrations selectively inhibit ligands interacting with FPR and FPRL-1. However, these agents are also known to interact with nuclear receptors and therefore suppress cytokine production and immune responses. These agents consequently also have anti-angiogenic effects and we are investigating their effects on in vivo tumor growth in SCID mice. In collaboration with Dr. M. Cushman at Indiana University we have shown that cosalane compounds interfere with RANTES capacity to interact with CCR1 receptors. These compounds also have anti-angiogenic effects and are being tested on human tumor models in SCID mice. Another component in Chinese anti-inflammatory medicinals known as shikonin was found to selectively interfere with CCR1-ligand interactions. However, it also blocks the chemotactic effect of all chemokines by interfering with GPCR initiated signal transduction. We are at present studying the mechanism of action of this potentially potent anti-inflammatory and anti angiogenic agent.