You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Gene"].

Please return the output as a JSON object of the format: {"Gene": ["IGF", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A Critical Role for CD200R Signaling in Limiting the Growth and Metastasis of CD200+ Melanoma. CD200 is a cell surface glycoprotein that functions through engaging CD200R on cells of the myeloid lineage and inhibits their functions. Expression of CD200 was implicated in a variety of human cancer cells, including melanoma cells; however, its roles in tumor growth and immunity are not clearly understood. In this study, we used CD200R-deficient mice and the B16 tumor model to evaluate this issue. We found that CD200R-deficient mice exhibited accelerated growth of CD200(+), but not CD200(-), B16 tumors. Strikingly, CD200R-deficient mice receiving CD200(+) B16 cells i.v. exhibited massive tumor growth in multiple organs, including liver, lung, kidney, and peritoneal cavity, whereas the growth of the same tumors in wild-type mice was limited. CD200(+) tumors grown in CD200R-deficient mice contained higher numbers of CD11b(+)Ly6C(+) myeloid cells, exhibited increased expression of VEGF and HIF1α genes with increased angiogenesis, and showed significantly reduced infiltration of CD4(+) and CD8(+) T cells, presumably as the result of reduced expression of T cell chemokines, such as CXCL9 and CXCL16. The liver from CD200R-deficient mice, under metastatic growth of CD200(+) tumors, contained significantly increased numbers of CD11b(+)Gr1(-) myeloid cells and Foxp3(+) regulatory T cells and reduced numbers of NK cells. Liver T cells also had a reduced capacity to produce IFN-γ or TNF-α. Taken together, we revealed a critical role for CD200R signaling in limiting the growth and metastasis of CD200(+) tumors. Thus, targeting CD200R signaling may potentially interfere with the metastatic growth of CD200(+) tumors, like melanoma.
{"Gene": ["CD8", "CD200R", "chemokines", "CXCL9", "TNF-\u03b1", "Gr1", "Foxp3", "CD4", "CXCL16", "Ly6C", "CD200", "CD11b", "IFN-\u03b3", "VEGF", "HIF1\u03b1", "B16 tumor"]}