PROLIFERATIVE CONDITIONING OF TUMOR-COMPETENT DENDRITIC CELL PRECURSORS

描述(申请人提供)：树突状细胞(DC)可以确定强大的细胞介导的免疫是否构成对抗原挑战的适当反应。干细胞动员治疗可用于在荷瘤宿主体内增殖和分布DC前体，但也观察到FltSL+GMCSF等动员治疗可促进免疫抑制和促进肿瘤进展。我们最近发现，FK3L+IL6对小鼠骨髓(BM)的动员是一种非常有前途的DC动员策略。与FltSL+GMCSF相比，Flt3L+IL6可促进CD34pos干细胞的大量增殖，但与FltSL+GMCSF相比，(1)FltSI+ILG可抢占正常多系造血细胞，有利于DC向全球分化；(2)促进对Toll样受体(TLR)激动剂的一致应答，极大地促进DC1型极化和IL-12p70的分泌；(3)允许DC自发成熟，绕过对CD40配体或Toll样受体(TLR)激动剂等正常信号的要求；(4)对肿瘤相关免疫抑制药如IL-10、转化生长因子-3(TGF-3)、血管内皮生长因子(VEGF)和前列腺素E_2(PGE2)具有抵抗作用；(5)通过加速Dc1极化诱导对肿瘤接触本身作出反应的能力，包括产生IL-12。有了这些特殊的特性，Flt3L+IL6条件下的DC暴露在活的肿瘤细胞中也显示出优越的逆转耐受和促进具有治疗能力的肿瘤特异性T细胞增殖的能力。重要的是，如果在增殖性条件反射过程中也存在GM-CSF，那么Flt3L+IL6 DC调节的这些有利影响就完全被取消了。本项目的目的是：(1)鉴定使FU3L+IL6条件下的小鼠树突状细胞在治疗方面具有优势的机制，以便在人树突状细胞中诱导出相同的特性；(2)鉴定和优化Flt3L+IL6动员对荷瘤小鼠的治疗作用，并正式比较rlL6与强大的设计细胞因子HyperlLG的作用；(3)比较人单核细胞来源的DC与人CD34pos BM细胞在Flt3L+IL6+GMCSF条件下增殖后的功能，包括TLR的表达。报告摘要：树突状细胞(DC)是人体内培养免疫系统识别和摧毁癌症的最佳细胞。我们已经确定了一种特殊的治疗方法，FltSL加IL6，可以产生更好的DC激活，我们希望这将提供一种更有效的抗癌治疗。该项目旨在提供将这项研究用于治疗癌症患者的临床试验所需的信息。

DESCRIPTION (provided by applicant): Dendritic cells (DCs) can determine whether or not robust cell-mediated immunity constitutes the appropriate response to antigenic challenge. Stem cell mobilizing treatments can be employed to proliferate and distribute DC precursors throughout the tumor-bearing host, but mobilization treatments such as FltSL+GMCSF have also been observed to promote immunosuppression and favor tumor progression. We recently identified that mouse bone marrow (BM) conditioning with FK3L+IL6 is an exceptionally promising strategy for DC mobilization. Flt3L+IL6 causes abundant proliferation of CD34pos stem cells, comparably to FltSL+GMCSF, but in contrast to FltSL+GMCSF, (1) FltSI+ILG conditioning preempts normal multilineage hematopoiesis in favor of nearly global DC differentiation; (2) it promotes uniform responsiveness to toll-like receptor (TLR) agonists, greatly facilitating DC1-type polarization and IL-12p70 secretion; (3) it licenses spontaneous DC maturation, bypassing normal requirements for signals such as CD40 ligand or toll-like receptor (TLR) agonists; (4) it confers resistance to tumor-associated immunosuppressants such as IL-10, TGF-(3, VEGF and PGE2; (5) it induces the capacity to respond to tumor contact itself with accelerated DC1 polarization, including IL-12 production. With these exceptional properties, Flt3L+IL6 conditioned DCs exposed to viable tumor cells also display a superior capacity to reverse tolerance and promote proliferation of therapeutically potent, tumor-specific T cells. Importantly, these favorable impacts of Flt3L+IL6 DC conditioning are completely abrogated if GM-CSF is also present during proliferative conditioning. This project's aims are: (1) to characterize the mechanisms which render FU3L+IL6 conditioned mouse DCs therapeutically superior, so that the same properties can be elicited in human DCs; (2) to characterize and optimize the therapeutic impacts of Flt3L+IL6 mobilization in tumor-bearing mice, with formal comparisons of rlL6 to the potent designer cytokine hyperlLG; (3) to compare the function, including TLR expression, of human monocyte-derived DCs with human CD34pos BM cells after the latter have been proliferatively conditioned with Flt3L+IL6 vs FltSL+GMCSF. Lay summary: Dendritic cells (DCs) are the body's best cell for educating the immune system to recognize and destroy cancer. We have identified that a particular treatment, FltSL plus IL6, results in superior activation of DCs, which we hope will provide a more effective treatment against cancer. This project aims to provide the information needed to bring this research to a clinical trial for treating cancer patients.