VISTA, a novel regulator of immunity and autoimmunity

描述(申请人提供)：我们发现了一种新的、造血受限的、结构独特的免疫球蛋白超家族抑制配体，其胞外结构域与B7家族配体PD-L1同源，并对免疫功能有深远的影响。它被命名为含V区免疫球蛋白的T细胞激活抑制因子(Vista)。Vista仅在造血室内，最显著的是髓系抗原呈递细胞，在CD4T细胞和Foxp3调节性T细胞(Treg)上的强度较低。一种可溶性的Vista-Ig融合蛋白，或天然Vista，在体外可以深刻地抑制T细胞的活性并诱导Foxp3的表达。封闭的抗Vista单抗干扰Vista诱导的抑制和加强实验性变态反应性脑脊髓炎(EAE)。Vista-/-小鼠有自发性炎症性疾病的早期迹象。与所有其他PD配体相关分子不同，Vista的造血抑制作用及其深刻的抑制活性和独特的结构特征表明，Vista是一种新的、功能上非冗余的、中枢的、负向免疫调节因子。这项建议的具体目的是：1.确定Vista如何抑制致病脑源性T细胞的发展。Vista控制致病的、髓鞘反应性的CD4T细胞发展的机制将在接受Vista治疗的小鼠、Vista-/-或有条件表达VISTAflox/Flox的小鼠中确定。这些方法将描述EAE中表达在CD4T细胞、Treg、DC和髓样细胞上的Vista的功能。2.对Vista进行结构研究，确定Vista功能的分子决定因素，并协助生产具有生物活性的Vista-Ig蛋白用于治疗。结构研究将确定Vista功能背后的化学和物理决定因素以及组织性质。一个独特的初级序列签名预测Vista拥有独特的特征，包括Ig-折叠体的新变体和意想不到的自关联模式。3)绘制Vista诱导的信号级联图谱，鉴定Vista受体(R)。我们已经生产出识别Vista R承载细胞的多聚体Vista分子。通过表达克隆，可以鉴定出Vista R。此外，还将描述Vista R触发的早期信号级联。4.以Vista通路为靶点进行自身免疫干预。这一特定目的的目的是确定通过VistA途径的夸大信号是否会抑制免疫并对自身免疫性疾病起到治疗作用。

DESCRIPTION (provided by applicant): We have discovered, characterized and functionally defined a novel, hematopoietically-restricted, structurally- distinct, Ig-superfamily inhibitory ligand whose extracellular domain bears homology to the B7 family ligand PD- L1 and profoundly impacts on immunity. It is named V-region Immunoglobulin-containing Suppressor of T cell Activation (VISTA). VISTA is exclusively within the hematopoietic compartment, most prominently on myeloid antigen-presenting cells, with lower intensity on CD4+ T cells and a subset of Foxp3+ regulatory T cells (Treg). A soluble VISTA-Ig fusion protein, or natural VISTA profoundly inhibits in vitro T activities and induces Foxp3 expression. A blocking anti-VISTA mab interfered with VISTA-induced suppression and intensified experimental allergic encephalomyelitis (EAE). VISTA-/- mice have early indications of spontaneous inflammatory disease. Unlike all other PD-Ligand-related molecules, the hematopoietic restriction of VISTA together with its profound suppressive activities and unique structural features, illustrates that VISTA is a novel, functionally non-redundant, central, negative regulator of immunity. The Specific Aims of this proposal are: 1. Determine how VISTA suppresses the development of pathogenic encephalitogenic T cells. The mechanisms through which VISTA controls the development of pathogenic, myelin-reactive CD4+ T cells will be determined in mice treated with ¿VISTA, in VISTA-/- or in mice that conditionally express VISTAflox/flox. Such approaches will delineate the function of VISTA expressed on CD4+ T cells, Treg, DCs and myeloid cells in EAE. 2. To perform structural studies on VISTA and define the molecular determinants of VISTA function and assist in producing biologically active VISTA-Ig proteins for therapy. Structural studies will identify the chemical and physical determinants and organizational properties that underlie VISTA function. A distinctive primary sequence signature predicts that VISTA possesses unique features, including a novel variation of the Ig-fold and an unexpected mode of self-association. 3) To map the signaling cascades induced by VISTA and identify the VISTA Receptor (R). We have produced multimeric VISTA molecules that identify VISTA R bearing cells. Through expression cloning the VISTA R will be identified. In addition, the early signaling cascades of VISTA R triggering will be delineated. 4. Target the VISTA pathway for immune intervention in autoimmunity. The purpose of this specific aim is to determine if exaggerated signaling via the VISTA pathway will suppress immunity and exert a therapeutic benefit on autoimmune disease.