Mechanisms of Immune Evasion by Ocular Tumors

描述（由申请人提供）：尽管黑色素瘤特异性CD8+细胞溶解T淋巴细胞（CTL）反应被诱导，但黑素瘤仍在眼睛内发展，这表明这些肿瘤以某种方式逃避了杀瘤CTL。髓系细胞浸润的葡萄膜黑色素瘤与患者预后不良相关，我们首次在动物模型中证明，在眼前房控制肿瘤生长的失败与CD11b+髓系细胞的积累有关，CD11b+髓系细胞通过一氧化氮（NO）的产生在体外抑制CTL反应。因此，我们假设骨髓细胞通过抑制肿瘤微环境中的CTL反应来促进眼部肿瘤的生长。我们在初步研究中证实了新的观察结果，即GR-1+ F4/80阴性CD11b+细胞积聚在对CTL反应有抵抗力的眼部肿瘤中，而在对CTL反应敏感的皮肤中发展的相同肿瘤则被GR-1阴性/ F4/80+ CD11b+细胞浸润。因此，通过减弱先天和适应性免疫反应来维持眼内“免疫特权”的免疫抑制机制可能会使眼肿瘤相关的CD11b+细胞转向免疫抑制型而非杀瘤型，并直接抑制CTL反应。我们的特异目的将测试三种相关的替代假设，这些假设是关于在眼肿瘤微环境中抑制CTL反应的机制。在目标1中，我们将直接确定肿瘤相关CD11b+细胞亚群对CTL效应物的杀肿瘤活性的影响，方法是在过继转移肿瘤特异性CTL之前，在已建立眼部或皮肤肿瘤的小鼠中选择性地消除GR-1+细胞、F4/80+细胞或两种细胞群。在目标2中，我们将通过将肿瘤特异性CTL转移到NO产生不足的荷瘤小鼠中，来确定NO产生对CTL杀伤肿瘤活性的影响。我们还将直接评估从皮肤和眼睛肿瘤中分离的CD11b+细胞亚群的NO介导的免疫抑制和杀瘤活性，以确定眼睛内CD11b+细胞抑制的杀瘤活性是否有助于眼部肿瘤的进展。在Aim #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体内，来确定免疫抑制分子（FasL、PD-1L、Trail和TGF-¿）的眼部表达对CTL杀瘤活性的影响。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。本应用将确定骨髓细胞在眼肿瘤微环境中抑制杀瘤免疫反应的影响。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，促进眼部肿瘤消除和防止转移。

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.