Mechanisms of Immune Evasion by Ocular Tumors

描述(申请人提供)：尽管诱导了黑色素瘤特异性CD8+细胞溶解T淋巴细胞(CTL)反应，但黑色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。被髓系细胞浸润性葡萄膜黑色素瘤与患者预后不良有关，我们首次在动物模型中证明，未能控制眼前房肿瘤生长与CD11b+髓系细胞积聚有关，CD11b+髓系细胞在体外通过产生一氧化氮(NO)抑制CTL反应。因此，我们假设髓系细胞通过抑制肿瘤微环境中的CTL反应来促进眼肿瘤的生长。我们在初步研究中证实，GR-1+F4/80阴性的CD11b+细胞聚集在对CTL反应耐受的眼部肿瘤内，而在皮肤内发展的对CTL敏感的肿瘤则被GR-1阴性/F4/80+CD11b+细胞渗透。因此，免疫抑制机制通过减弱先天和获得性免疫反应来维持眼内的免疫豁免，可能使眼肿瘤相关CD11b+细胞向免疫抑制型而不是杀瘤型转变，并直接抑制CTL反应。我们的具体目标将测试三个相关的替代假说，关于在眼肿瘤微环境中抑制CTL反应的机制。在目标1中，我们将在过继转移肿瘤特异性CTL之前，通过选择性地清除眼部或皮肤肿瘤小鼠的GR-1+细胞和/或F4/80+细胞，直接确定肿瘤相关CD11b+细胞亚群对CTL效应器杀瘤活性的影响。在第二个目标中，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身上来确定NO产生对CTL杀瘤活性的影响。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，以确定眼内CD11b+细胞抑制的肿瘤杀伤活性是否有助于眼部肿瘤的进展。在目标3中，我们将通过在肿瘤攻击前将肿瘤特异性CTL转移到免疫抑制分子(FasL、PD-1L、Trail和TGF-β)缺陷的小鼠体内，来确定免疫抑制分子(FasL、PD-1L、Trail和TGF-β)的眼睛表达对CTL杀瘤活性的影响。公共卫生相关性：髓系细胞浸润性葡萄膜黑色素瘤与患者预后不良有关。这项应用将确定眼部肿瘤微环境中髓系细胞对抑制杀瘤免疫反应的影响。了解髓系细胞在免疫抑制和肿瘤生长中的作用，可能会导致免疫疗法的发展，促进眼内肿瘤的消除和防止转移。

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.