Notch Signaling Dictates CD4+T cell Activation in Diabetic Wounds

项目总结 2型糖尿病(T2D)的继发并发症，包括伤口愈合受损， 正在增加，治疗选择仍然有限，而且只有轻微的效果。失败 T2D患者的伤口愈合情况是截肢的最常见原因 并有50%的5年死亡率。因此，迫切需要理解 T2D创伤的病理生理学以确定可作为治疗靶点的新机制。 在正常伤口愈合中，巨噬细胞之间的协调免疫反应(MφS)，以及 CD4+T细胞对于受控的炎症反应和组织修复至关重要。尽管 损伤后这些相互作用的分子机制还不是很清楚，我们的 小组和其他人已经发现Notch信号在伤口愈合中起着关键作用。 根据特定的配体-受体相互作用，CD4+T细胞激活导致 分化成特定的T细胞表型。已经观察到，CD4+T细胞调节(Treg) 细胞是确保正常组织修复的关键，而TH17表型则促进过度 炎症和损害愈合；然而，控制CD4+T细胞激活的机制 伤口组织尚不清楚。我们的初步数据显示，Notch信号在 糖尿病患者MφS/CD4+T细胞可导致Th17升高，Treg减少，炎症过度 以及病理性愈合。而创面过程中Treg/Th17分化的精确调控 修复尚不清楚，我们的初步数据表明，Notch配体DLL4在 糖尿病创伤MφS与CD4+T细胞上Notch2受体相互作用 促进炎症性TH17表型，而不是Treg分化。我们假设 糖尿病创面中DLL4介导的Notch受体信号极化CD4+T细胞 伤口朝向TH17，并促进慢性炎症和无法愈合 局部阻断DLL4可减轻糖尿病小鼠炎症并促进愈合 伤口。为了验证我们的假设，我们将追求以下具体目标： 1)探讨Notch 2受体激活在急性髓系白血病Treg/Th17分化中的作用 和慢性糖尿病小鼠伤口模型。 2)确定DLL4配体的遗传或局部治疗封闭是否限制了TH17 分化，减少炎症，促进糖尿病伤口修复。

PROJECT SUMMARY Secondary complications of type 2 diabetes (T2D), including impaired wound healing, are increasing, and therapeutic options remain limited and only marginally effective. Failure of wound healing in T2D patients represents the most common cause of amputation in the US and has an a 5-year mortality rate of 50%. Thus, a critical need exists for understanding the pathophysiology of T2D woundsto identify novel mechanisms that can be therapeutically targeted. In normal wound healing, a coordinated immune response between macrophages (Mφs), and CD4+T cells is critical for a controlled inflammatory response and tissue repair. Although the molecular mechanisms that dictate these interactions following injury are not well understood, our group and others have identified that Notch signaling plays a critical role in wound healing. Depending on the specific ligand-receptor interactions, CD4+T cell activation results in differentiation into a specific T cell phenotype. It has been observed that CD4+T regulatory (Treg) cells are critical to ensure normal tissue repair, while TH17 phenotypes promote excess inflammation and impair healing; however, the mechanisms that control CD4+T cell activation in wound tissue are unknown. Our preliminary data show that increased Notch signaling between Mφs/CD4+T cells in diabetes can lead to increased TH17, decreased Tregs, excess inflammation and pathologic healing. While the precise regulation of Treg/TH17 differentiation during wound repair is unclear, our preliminary data identify that the Notch ligand, DLL4, is upregulated in diabetic wound Mφs, and that DLL4 interactions with the Notch 2 receptor on CD4+T cells promotes an inflammatory TH17 phenotype as opposed to Treg differentiation. We hypothesize that DLL4-mediated Notch receptor signaling in diabetic wounds polarizes CD4+T cells in the wound towards TH17 and promotes chronic inflammation and non-healing and that local blockade of DLL4 will decrease inflammation and improve healing in diabetic murine wounds. To test our hypotheses, we will pursue the following Specific Aims: 1) To identify the role of Notch 2 receptor activation on Treg/TH17 differentiation in acute and chronic diabetic murine wound models. 2) To determine if genetic or local therapeutic blockage of DLL4 ligand limits TH17 differentiation, decreases inflammation and improves diabetic wound repair.