Mechanisms of Immune Evasion by Ocular Tumors

描述（由申请人提供）：尽管黑色素瘤特异性CD 8+细胞溶解性T淋巴细胞（CTL）应答的诱导表明这些肿瘤以某种方式逃避了杀肿瘤CTL，但黑色素瘤仍在眼内发展。被髓样细胞浸润的葡萄膜黑色素瘤与患者预后不良相关，并且我们首次在动物模型中证明，未能控制眼前房中的肿瘤生长与CD 11b+髓样细胞的积累相关，所述CD 11b+髓样细胞通过一氧化氮（NO）的产生在体外抑制CTL应答。因此，我们假设髓系细胞通过抑制肿瘤微环境中的CTL应答来促进眼部肿瘤生长。我们在初步研究中证实了新的观察结果，即GR-1+ F4/80阴性CD 11b+细胞在对CTL应答具有抗性的眼部肿瘤内积累，而在对CTL敏感的皮肤内发育的相同肿瘤被GR-1阴性/ F4/80+ CD 11b+细胞浸润。因此，通过减弱先天性和适应性免疫应答来维持眼内“免疫赦免”的免疫抑制机制可能使眼肿瘤相关的CD 11b+细胞向免疫抑制而非杀肿瘤类型调节，以及直接抑制CTL应答。我们的特定目标将测试三个相关的替代假说的机制，抑制CTL反应的眼部肿瘤微环境。在目标#1中，我们将通过在过继转移肿瘤特异性CTL之前选择性消除已建立眼或皮肤肿瘤的小鼠中的GR-1+细胞、F4/80+细胞或这两种细胞群，直接确定肿瘤相关CD 11b+细胞亚群对CTL效应物的杀肿瘤活性的影响。在目标#2中，我们将通过将肿瘤特异性CTL转移到NO产生缺陷的荷瘤小鼠中来确定NO产生对CTL的杀肿瘤活性的影响。我们还将直接评价从皮肤和眼肿瘤中分离的CD 11b+细胞亚群的NO介导的免疫抑制和杀肿瘤活性，以确定眼内CD 11b+细胞抑制的杀肿瘤活性是否有助于眼肿瘤进展。在目标#3中，我们将通过在肿瘤攻击前将肿瘤特异性CTL转移到缺乏这些分子的小鼠中来确定免疫抑制分子（FasL、PD-1 L、Trail和TGF-β）的眼部表达对CTL的杀肿瘤活性的影响。公共卫生相关性：髓系细胞浸润的葡萄膜黑色素瘤与患者预后不良相关。本申请将确定骨髓细胞对眼肿瘤微环境中杀肿瘤免疫应答抑制的影响。了解骨髓细胞对免疫抑制和肿瘤生长的贡献可能会导致免疫疗法的发展，促进眼睛中的肿瘤消除并防止转移。

DESCRIPTION (provided by applicant): Melanomas develop within the eye despite the induction of melanoma-specific CD8+ cytolytic T lymphocyte (CTL) responses which indicates that these tumors somehow evade tumoricidal CTL. Uveal melanomas that are infiltrated by myeloid cells are associated with a poor patient prognosis and we were first to demonstrate in an animal model that the failure to control tumor growth in the anterior chamber of the eye correlates with the accumulation of CD11b+ myeloid cells which inhibit CTL responses in vitro via nitric oxide (NO) production. Accordingly, we hypothesize that myeloid cells promote ocular tumor growth by inhibiting CTL responses within the tumor microenvironment. We demonstrate in preliminary studies the novel observation that GR-1+ F4/80 negative CD11b+ cells accumulate within ocular tumors which are resistant to CTL responses, whereas the same tumors developing within the skin which are sensitive to CTL are infiltrated by GR-1 negative/ F4/80+ CD11b+ cells. Hence, immune suppressive mechanisms which maintain "immune privilege" within the eye by attenuating innate and adaptive immune responses may condition ocular tumor associated CD11b+ cells toward an immunosuppressive and not tumoricidal type as well as directly inhibit CTL responses. Our Specific Aims will test three related alternative hypotheses about the mechanisms that inhibit CTL responses within the ocular tumor microenvironment. In Aim #1 we will directly determine the influence of tumor associated CD11b+ cell subsets on the tumoricidal activity of CTL effectors by selectively eliminating GR-1+ cells , F4/80+ cells or both cell populations in mice with established eye or skin tumors prior to adoptive transfer of tumor-specific CTL. In Aim #2 we will determine the influence of NO production on the tumoricidal activity of CTL by transferring tumor-specific CTL into tumor bearing mice that are deficient in NO production. We will also directly evaluate NO mediated immunosuppressive and tumoricidal activity of CD11b+ cell subsets isolated from skin and eye tumors to determine whether inhibited tumoricidal activity by CD11b+ cells within the eye contributes to ocular tumor progression. In Aim #3 we will determine the influence of ocular expression of immune suppressive molecules (FasL, PD-1L, Trail, and TGF-¿) on the tumoricidal activity of CTL by transferring tumor-specific CTL into mice deficient in these molecules before tumor challenge. PUBLIC HEALTH RELEVANCE: Uveal melanomas infiltrated by myeloid cells are associated with a poor patient prognosis. This application will determine the influence of myeloid cells on suppression of tumoricidal immune responses in an ocular tumor microenvironment. Understanding the contribution of myeloid cells to immune suppression and tumor growth may lead to the development of immunotherapies that promote tumor elimination in the eye and prevent metastasis.