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

项目摘要 细胞因子IL-27是在感染期间抑制免疫亢进的关键机制。期间 弓形虫感染后，IL-27的缺失导致致死性的CD 4 + T细胞介导的免疫应答， 以及升高的炎性细胞因子反应和全身血栓形成。这些机制如何调节 病理，并可能相互交叉，是不清楚的。通过CD 4 + T细胞的GM-CSF产生是 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导致 感染的IL-27-/-小鼠的存活率。GM-CSF可以增强单核细胞和巨噬细胞的反应， 有助于免疫血栓形成，这表明这可能是一个潜在的中枢机制， 介导的保护得以实现。此外，我们已经观察到IL-27的缺失导致增强的免疫应答。 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 造血干细胞（LT-HSC）确实并且可以通过IL-27偏向于几种分化途径。 因此，我们假设IL-27的缺失导致感染期间单核细胞发育增强， 在感染的后期又可能受到GM-CSF的影响，从而介导病理学。为了验证这一点，我们 分析HSC发育和单核细胞表型是否受IL-27的影响， 弓形虫病和单核细胞反应增强在这种情况下是病理性的。完成这项工作的方法是 通过细胞转移、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介导的病理机制， 没有IL-27。这将通过在IL-27-/-小鼠感染期间阻断GM-CSF并分析GM-CSF的表达来完成。 与病理学有关的免疫参数在此之后，GM-CSF受体将被选择性地去除， 从潜在的细胞类型，以确定这是否拯救感染期间的IL-27缺陷小鼠。所有这些 研究将增强我们对细胞因子驱动的病理学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.