RESUMO
Tumors are often comprised of microenvironments (TMEs) with a high proportion of cells and molecules that regulate immunity. Peritoneal cavity (PerC) cell culture reproduces key features of TMEs as lymphocyte proliferation is suppressed by PerC macrophages (MÏs). We monitored the expression of T cell stimulatory (Class II MHC, B7) and inhibitory (PD-L1) molecules by PerC APCs before and after culture and report here that IFNγ-driven PD-L1 expression increased markedly on PerC MÏs after TCR ligation, even more so than seen with direct APC activation by LPS. Considering the high APC composition of and pronounced PD-L1 expression by PerC cells, it was surprising that blocking PD-1/PD-L1 interaction by mAb neutralization or genetic ablation did not relieve suppression. This result parallels TME challenges observed in the clinic and validates the need for further study of this culture model to inform strategies to promote anti-tumor immunity.
Assuntos
Antígeno B7-H1/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Macrófagos Peritoneais/metabolismo , Macrófagos/metabolismo , Animais , Antígeno B7-1/imunologia , Antígeno B7-1/metabolismo , Antígeno B7-H1/biossíntese , Feminino , Antígenos de Histocompatibilidade Classe II/metabolismo , Interferon gama/imunologia , Interferon gama/metabolismo , Ativação Linfocitária/imunologia , Macrófagos/imunologia , Macrófagos Peritoneais/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Imunológicos , Cultura Primária de Células , Receptor de Morte Celular Programada 1/biossíntese , Receptor de Morte Celular Programada 1/imunologia , Microambiente Tumoral/imunologiaRESUMO
Erythropoietin (EPO), used to treat anemia in cancer patients, has been reported to accelerate tumor progression and increase mortality. Research of the mechanism for this effect has focused upon EPOR expression by tumor cells. We model the high macrophage to lymphocyte ratio found in tumor microenvironments (TMEs) by culturing peritoneal cavity (PerC) cells that naturally have a high macrophage to T cell ratio. Following TCR ligation, C57BL/6J PerC T cell proliferation is suppressed due to IFNγ-triggered inducible nitric oxide synthase (iNOS) expression. EPO was tested in the PerC culture model and found to increase T cell suppression. This effect could be abrogated by inhibiting iNOS by enzyme inhibition, genetic ablation, or blocking IFNγ signaling. Flow cytometry revealed the EPOR on CD11b(+)F4/80(+) macrophages. These results suggest that EPO could increase T cell suppression in the TME by acting directly on macrophages.
