Impact of IL-27 on monocyte responses to Toxoplasma gondii infection

项目摘要 细胞因子IL-27是抑制感染过程中免疫功能亢进的重要机制。在.期间 弓形虫感染后，IL-27的丢失会导致致死性的、CD4+T细胞介导的免疫应答。 以及炎性细胞因子反应升高和全身血栓形成。这些机制如何调节 病理学，并可能相互交叉，目前尚不清楚。由CD4+T细胞产生的GM-CSF是 在IL-27缺陷小鼠中增强，我们最近观察到，阻断这种细胞因子会导致 感染IL-27-/-小鼠的存活。GM-CSF可增强单核细胞和巨噬细胞反应 促进免疫血栓形成，提示这可能是IL-27的一个潜在的中枢机制 实现了中介保护。此外，我们还观察到，IL-27的丢失导致 单核细胞生成和单核细胞对感染的反应。单核细胞不表达IL-27受体，但长期 在IL-27的作用下，造血干细胞(LT-HSCs)确实并可能偏向于几种分化途径。 因此，我们假设，在感染过程中，IL-27的丢失导致单核细胞发育增强，从而 在感染的后期阶段可能又会受到GM-CSF的影响，从而介导病理。为了测试这一点，我们将 分析IL-27对HSC早期发育和单核细胞表型的影响 在这种情况下，弓形虫病和单核细胞反应增强是病理性的。这将会实现的 通过结合细胞转移、高维流式细胞术和scrna-seq以及选择性 耗尽实验。然后我们将确定GM-CSF在急性髓细胞白血病中的作用机制。 IL-27缺失。这将通过在感染IL-27-/-小鼠期间阻断GM-CSF并分析 免疫参数与病理有关。之后，GM-CSF受体将被选择性地移除 从潜在的细胞类型来确定这是否在感染期间拯救了IL-27缺陷的小鼠。加在一起，这些 研究将加深我们对细胞因子驱动的病理机制和免疫保护机制的理解。

Project Summary The cytokine IL-27 is a critical mechanism for restraining immune hyperactivity during infection. During Toxoplasma gondii infection, the loss of IL-27 results in a lethal, CD4+ T cell mediated immune response as well as elevated inflammatory cytokine responses and systemic thrombosis. How these mechanisms mediate pathology, and possibly intersect with one another, is unclear. GM-CSF production by CD4+ T cells is enhanced in IL-27 deficient mice, and we have recently observed that blockade of this cytokine leads to survival of infected IL-27-/- mice. GM-CSF can enhance monocyte and macrophage responses as well as contribute to immunothrombosis, suggesting that this may be a potential central mechanism by which IL-27 mediated protection is achieved. Additionally, we have observed that the loss of IL-27 results in enhanced monopoiesis and monocyte responses to infection. Monocytes do not express the IL-27 receptor, but long-term hematopoietic stem cells (LT-HSCs) do and can be skewed towards several differentiation pathways by IL-27. Thus, we hypothesize that the loss of IL-27 leads to enhanced monocyte development during infection which may in turn be impacted by GM-CSF during later stages of infection to mediate pathology. To test this, we will analyze if HSC development and monocyte phenotypes are impacted by IL-27 during the early stages of toxoplasmosis and if enhanced monocytes responses are pathological in this setting. This will be achieved through a combination of cell transfers, high-dimensional flow cytometry, and scRNA-seq as well as selective depletion experiments. We will then determine the mechanisms by which GM-CSF mediates pathology in the absence of IL-27. This will be done by blocking GM-CSF during infection of IL-27-/- mice and analyzing the immune parameters connected to pathology. Following this, the GM-CSF receptor will be selectively removed from potential cell types to determine if this rescues IL-27 deficient mice during infection. Together, these studies will enhance our understanding of cytokine driven pathologies and mechanisms of immune protection.