Characterization of the interaction between inflammation and cancer progression

本项目的目标是研究细胞因子在体内调节炎症和宿主抗肿瘤免疫反应的细胞和分子机制，特别是当它们与肿瘤和器官微环境之间的复杂细胞相互作用有关时。我们的第一个方法是描述肿瘤进展过程中肿瘤浸润性白细胞的特征。使用可移植的转移性肾细胞癌，我们正在分析原发肿瘤内的白细胞，这些白细胞在肾脏以及肺和肝脏中发展，分别作为肿瘤转移的主要和次要部位。趋化因子是趋化细胞因子，用于将特定的白细胞亚群招募到正在进行的炎症反应区域。我们正在利用缺乏各种趋化因子受体的小鼠来确定单核细胞、T细胞和其他炎症细胞被招募到肿瘤部位的机制。一旦出现在发展中的肿瘤部位，这些细胞就能够产生许多不同的可溶性介质，如干扰素、一氧化氮和血管内皮生长因子，这些都可能影响肿瘤的进展。通过调节这些细胞类型在肿瘤内聚集的能力，我们正在确定这些细胞在原发肿瘤进展和远处器官转移中所起的作用。我们的免疫治疗方案包括IL-2或IL-15联合CD40激动型抗体。在用这种组合治疗荷瘤小鼠后，我们已经确定了巨噬细胞和T细胞的招募，这似乎是抗肿瘤反应的关键介质。我们的数据已经说明了单独使用抗CD40与联合使用IL-2在生物效应方面存在显著机制差异的可能性，其中包括协同上调干扰素和控制肿瘤负担的一氧化氮表达。在另一种方法中，我们已经开始分析树突状细胞在免疫疗法实现的抗肿瘤反应中所起的作用。IL-12是一种强大的免疫调节细胞因子，其本身具有显著的抗肿瘤效果。与脾等淋巴器官相比，IL-12治疗增加了肝脏中的树突状细胞。我们目前正在分析将IL-12与其他免疫调节细胞因子如IL-2或IL-15相结合的疗法是否通过增强这些重要效应细胞的抗原提呈能力来提供更有效的抗肾癌免疫反应。此外，树突状细胞与NK和NK-T细胞之间存在动态串扰，调节这些细胞的数量或功能的治疗可能会对DC启动T细胞以进行特异性抗肿瘤反应的能力产生重大影响。此外，我们还发现在肿瘤微环境中有一种特殊的T调节细胞聚集，这可能有助于抑制抗肿瘤反应。我们发现肿瘤坏死因子α(TNFpha)是一种关键的促炎细胞因子，可能与T调节细胞的募集和/或扩增有关。我们正在通过分子和生化方法来靶向这种细胞因子，这些方法最终可能在临床上有用，以对抗抑制肿瘤微环境的建立。我们还确定了NK-T细胞可能的免疫抑制作用，目前我们正在开发免疫治疗方案，以减少这些细胞在不同器官中的数量和活性。通过表征炎症在肿瘤进展中的作用，这些重叠的方法有望导致免疫治疗方法的发展，从而扭曲炎症反应以对抗肿瘤生长。

The goal of this project is to investigate the cellular and molecular mechanisms by which cytokines regulate inflammation and host anti-tumor immune responses in vivo, particularly as they relate to the complex cellular interactions between the tumor and organ microenvironments. Our first approach is to characterize the profile of tumor-infiltrating leukocytes during tumor progression. Using a transplantable, metastatic renal cell carcinoma, we are analyzing leukocytes contained within the primary tumors that develop in the kidney as well as those in the lung and livers, which serve as primary and secondary sites of tumor metastases, respectively. Chemokines are chemotactic cytokines that serve to recruit specific leukocyte subsets into regions of ongoing inflammatory responses. We are utilizing mice deficient in various chemokine receptors to identify the mechanisms whereby monocytes, T cells and other inflammatory cells are recruited to the tumor site. Once present at the developing tumor site, these cells are capable of producing many different soluble mediators, such as interferon gamma (IFNγ), nitric oxide, and VEGF that may influence tumor progression. By regulating the ability of these cell types to accumulate within tumors, we are identifying the role that these cells play during both primary tumor progression and metastasis to distant organs. Our immunotherapeutic regimens include IL-2 or IL-15 in combination with agonistic antibody to CD40. After treating tumor-bearing mice with this combination, we have identified the recruitment of macrophages and T cells that appear to be critical mediators of anti-tumor responses. Our data have illustrated the potential for dramatic mechanistic differences in biological effects mediated by anti-CD40 alone versus its use in combination with IL-2 that includes the synergistic upregulation of IFNγ and nitric oxide expression that controls tumor burden. In another approach, we have begun to analyze the role that dendritic cells play during the anti-tumor responses achieved by immunotherapies. Treatment with IL-12, a potent immunoregulatory cytokine with dramatic anti-tumor effects on its own, increases dendritic cells differently in the liver as compared to lymphoid organs such as the spleen. We are currently analyzing whether therapies that combine IL-12 with other immunomodulatory cytokines such as IL-2 or IL-15 offer a more effective immune response against renal cell carcinoma by enhancing the antigen presenting capability of these important effector cells. Furthermore, there is dynamic cross-talk between dendritic cells and NK and NK-T cells and therapies that modulate the numbers or function of these cells may have significant impact upon the ability of DC to prime T cells for specific anti-tumor responses. In addition, we have identified a specific accumulation of T regulatory cells within the tumor microenvironment, which may serve to suppress anti-tumor responses. We have identified tumor necrosis factor alpha (TNFalpha), a critical proinflammatory cytokine, as possibly being involved in the recruitment and/or expansion of T regulatory cells. We are targeting this cytokine by molecular and biochemical approaches that may ultimately be useful in the clinic for counteracting the establishment of a suppressive tumor microenvironment. We have also identified a putative immunosuppressive role for NK-T cells and we are now developing immunotherapeutic regimens that reduce the numbers and activity of these cells in different organs. By characterizing the role of inflammation upon tumor progression, these overlapping approaches will hopefully lead to the development of immunotherapeutic approaches that skew the inflammatory response to counter tumor growth.