Consequences of Chemokine-Receptor Interactions: Immune

我们进一步的研究表明，参与先天宿主防御的抗菌肽也与宿主炎症细胞上的受体相互作用，导致适应性免疫反应。人粒细胞源性防御素对静止的幼稚T细胞和未成熟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，当在疫苗中共同施用-防御素时，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。在与Jacek Lubkowski博士领导的NCI生物物理学家的合作中，上皮细胞衍生的防御素对未成熟树突状细胞和静止记忆细胞具有趋化作用，这些细胞表达“LARC”的CCR6受体，具有与趋化因子相似的三级结构。Drs。我们实验室的De Yang和Oleg Chertov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cathelicidin （LL37）也可以通过与FPRL-1受体相互作用来调动参与宿主防御的白细胞。此外，经典的趋化受体如C5a、FPR和FPRL-1在未成熟和成熟树突状细胞上的表达已被证明可以进一步了解它们在加工和向T细胞递送抗原以帮助启动免疫反应中的作用。Oleg Chertov博士发现，中性粒细胞在脱颗粒过程中释放的组织蛋白酶G是一种吞噬细胞的化学引诱剂，如果与抗原一起使用，则可以作为疫苗的免疫佐剂。

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.