KLF10, CD4+ T cells, and transplant arteriopathy

移植相关性动脉病（transplant-associated arteriosclerosis，TAA）是移植物衰竭和受者死亡的主要原因 心脏移植后存活超过一年的患者，尽管在免疫抑制方面取得了进展。之一 导致TAA的早期事件是外膜周围炎性细胞的浸润和活化，包括T 细胞和巨噬细胞，随后形成弥漫性，同心的新生内膜，其中光滑 肌肉细胞和白细胞积聚。T细胞效应细胞和调节性T细胞都在免疫调节中发挥关键作用。 调节移植物炎症平衡。有趣的是，与年龄相关的T细胞反应性降低 有丝分裂原信号与提高同种异体移植物存活率有关。事实上，流行病学研究表明， 年龄较大的接受者比年轻接受者具有降低的同种异体移植物排斥率。因此，确定因素 减少T细胞活化可能潜在地影响急性和慢性心脏移植物排斥。 Kruppel样因子是细胞生长、分化和活化的转录调节因子。我们确定了一个 该家族的成员KLF10，其表达在T细胞中高度表达并随年龄增加。我们 发现TGF-b1应答因子KLF10调节T细胞效应子和T细胞的关键方面， 调节细胞功能。我们的初步研究揭示了KLF10在与年龄相关的T细胞减少中的新作用。 TAA中的细胞活化。主要组织相容性复合物II类（MHC II）不匹配的心脏移植物显示， 当移植到野生型（WT）或KLF10-/-小鼠的年轻受体中时，具有相似的TAA和存活率。在 相比之下，老年KLF 10-/-受体的同种异体移植物发生加速的TAA， 外膜T细胞和巨噬细胞，促炎标志物（例如IFN-γ，TNF-α，IL-6， 和MCP-1），并降低存活率。老年KLF10-/-CD4 + T细胞表现出Th1增强和T细胞减少 调节细胞（Treg）功能与CTLA-4表达减少有关，CTLA-4是一种免疫抑制分子， T细胞反应性的变化最后，将心脏移植物移植到年轻的KLF 10-/-宿主中， 接受较老的KLF10-/-T细胞（相对于较年轻的KLF10-/-T细胞）的患者显示出增加的TAA。机制研究 证明KLF10是由一种microRNA，miR-340靶向的，它与KLF10呈负表达， 增加年龄以调节TGF-b1/CTLA-4信号传导。这些观察结果为我们的中心研究提供了基础。 假设KLF10是T细胞对衰老和TAA反应性的关键调节因子。在AIM1中，我们 将探索调节老年和年轻T细胞效应器中KLF10表达的上游机制。在目标2中， 我们将确定老年人CD4-KLF10缺陷型中Th1和Treg细胞功能受损的分子基础。 TAA的关键小鼠。在Aim3中，我们将探讨KLF10表达改变对T细胞反应性的影响。 以及使用年轻和年老的T细胞特异性KLF10-KO小鼠和抗miR-340治疗剂的实验性TAA。的 这些研究的结果将提供关于KLF10在T细胞生物学、衰老和免疫功能中的重要见解。 可以作为调节T细胞反应性和TAA的新治疗策略的基础。

Transplant-associated arteriopathy (TAA) constitutes the major cause of graft failure and death in recipients who survive more than one year after cardiac transplantation, despite advances in immunosuppression. One of the early events leading to TAA is infiltration and activation of peri-adventitial inflammatory cells, including T cells and macrophages, which is followed by the formation of a diffuse, concentric neointima in which smooth muscle cells and leukocytes accumulate. Both T cell effectors and T regulatory cells play key roles in regulating the balance of allograft inflammation. Interestingly, age-related diminution of T cell responsiveness to mitogen signals have been linked to improved allograft survival. Indeed, epidemiological studies indicate that older recipients have reduced allograft rejection rates than younger recipients. As such, identification of factors that reduce activation of T cells could potentially impact both acute and chronic cardiac allograft rejection. Kruppel-like factors are transcriptional regulators of cell growth, differentiation, and activation. We identified a member of this family, KLF10, whose expression is highly expressed in T cells and increases with age. We identified that the TGF-b1-responsive factor, KLF10, regulates key aspects of both T cell effector and T regulatory cell function. Our preliminary studies uncover a novel role for KLF10 in age-related diminution of T cell activation in TAA. Major histocompatibility complex class II (MHC II)-mismatched cardiac allografts showed similar TAA and survival when transplanted into young recipients of either wild-type (WT) or KLF10-/- mice. In contrast, allografts in older KLF10-/- recipients developed accelerated TAA with increased accumulation of peri- adventitial T cells and macrophages, increased levels of pro-inflammatory markers (e.g. IFN-γ, TNF-a, IL-6, and MCP-1), and reduced survival. Older KLF10-/- CD4+ T cells exhibited enhanced Th1 and decreased T regulatory cell (Treg) function with reduced expression of CTLA-4, an immunosuppressive molecule implicated in T cell responsiveness with aging. Finally, cardiac allografts transplanted into younger KLF10-/- hosts receiving older KLF10-/- T cells (vs. younger KLF10-/- T cells) showed increased TAA. Mechanistic studies demonstrate that KLF10 is targeted by a microRNA, miR-340, that is inversely expressed with KLF10 with increasing age to regulate TGF-b1/CTLA-4 signaling. These observations provide the foundation for our central hypothesis that KLF10 serves as a critical regulator of T cell responsiveness with aging and TAA. In Aim1, we will explore the upstream mechanisms regulating KLF10 expression in old and young T cell effectors. In Aim2, we will determine the molecular basis for impaired Th1 and Treg cell function in older CD4-KLF10-deficient mice critical for TAA. In Aim3, we will explore the effect of altered KLF10 expression on T cell responsiveness and experimental TAA using young and old, T cell-specific KLF10-KO mice and anti-miR-340 therapeutics. The results of these studies will provide considerable insights regarding KLF10 function in T cell biology, aging, and may serve as the basis for novel therapeutic strategies to modulate T cell responsiveness and TAA.