Epithelial-released netrin-1 controls CD4 effector T cell trafficking during chro

描述（由申请人提供）：炎症性肠病（IBD）是一种复发缓解性疾病，在美国越来越多的患者中表现为慢性和衰弱性肠道炎症。具有Th 1表型的CD 4 T细胞在肠粘膜中的不适当积累在维持疾病病理中起着不可或缺的作用。因此，阻断CD 4 Th 1 T细胞运输到发炎的肠道是一个深入研究的领域。申请人最近的研究发现了神经元导向分子netrin-1在急性结肠炎期间阻断白细胞迁移的惊人作用9。然而，netrin-1在IBD中观察到的慢性炎症中的作用尚不清楚。令人兴奋的是，netrin-1治疗几乎完全逆转了组织学疾病，并显著降低了克罗恩病样回肠炎（TNFΔARE）小鼠回肠中效应CD 4 T细胞的数量。netrin-1处理后，在TNFΔARE回肠中观察到Th 1趋化因子受体CXCR 3和CCR 5的表达显著降低，表明netrin-1减弱了Th 1 T细胞应答。Netrin-1在体外阻止TNFΔARE CD 4 T细胞向特异性Th 1趋化因子迁移。体内归巢试验表明netrin-1阻断了TNFΔARE CD 4 T细胞向发炎回肠的运输，表明netrin-1对CD 4 T细胞迁移有直接影响。 申请人鉴定肠上皮是急性炎症期间netrin-1的主要来源，其中netrin-1在急性结肠炎中通过A2 B腺苷受体（A2 BAR）介导抗炎反应。有趣的是，A2 BAR在TNFΔARE CD 4 T细胞上高水平表达，并且netrin-1可以诱导A2 BAR信号传导。腺苷受体信号传导已涉及阻断趋化因子受体功能性应答，包括细胞迁移10 -12。基于这些发现，我们推测在慢性炎症过程中，肠上皮来源的netrin-1通过A2 B腺苷受体介导的信号通路抑制CD 4 Th 1 T细胞的运输。上皮特异性netrin-1缺失的新遗传模型将有助于阐明内源性netrin-1在慢性肠道炎症发展过程中的功能作用。体内和体外功能试验将鉴定netrin-1信号通路负责netrin-1在TNFΔARE回肠炎中的治疗作用。申请人将使用K 01机制，通过参加重点研讨会和会议来发展她的粘膜免疫学和T细胞生物学知识。她已经召集了一个委员会来帮助她沿着参加实践课程，该委员会将教育她进行CD 4 T细胞功能分析所需的技术。拟议研究的目标是使用遗传学和药理学方法来确定netrin-1在IBD中发生的慢性肠道炎症中的作用。"

DESCRIPTION (provided by applicant): Inflammatory bowel diseases (IBD) are relapsing remitting conditions that manifest as chronic and debilitating inflammation of the intestine in an ever-increasing number of patients in the USA. Inappropriate accumulation of CD4 T cells with a Th1 phenotype in the intestinal mucosa plays an indispensable role in maintaining disease pathology. As such blocking CD4 Th1 T cell trafficking to the inflamed intestine is an area of intense investigation. Recent investigations by the applicant unearthed a surprising role for the neuronal guidance molecule, netrin-1 in blocking leukocyte migration during acute colitis9. However, the role of netrin-1 in chronic inflammation as observed in IBD is unknown. Excitingly, netrin-1 treatment almost completely reversed histological disease and dramatically decreased the number of effector CD4 T cells in the ileum of mice with Crohn's-like ileitis (TNFΔARE). Following netrin-1 treatment a robust reduction in the expression of Th1 chemokine receptors, CXCR3 and CCR5, was observed in TNFΔARE ileum indicating netrin-1 attenuated a Th1 T cell response. Netrin-1 prevented TNFΔARE CD4 T cell migration towards specific Th1 chemokines in vitro. In vivo homing assays demonstrated netrin-1 blockade of TNFΔARE CD4 T cell trafficking to the inflamed ileum, pointing to a direct effect of netrin-1 on CD4 T cell migration. The applicant identified the intestinal epithelium as the major source of netrin-1 during acute inflammation with netrin-1 mediating an anti- inflammatory response through the A2B adenosine receptor (A2BAR) in acute colitis.Interestingly, the A2BAR is expressed to a high level on TNFΔARE CD4 T cells and netrin-1 can induce A2BAR signaling. Adenosine receptor signaling has been implicated in blocking chemokine receptor functional responses, including cell migration10-12. Based on these findings, we hypothesize that during chronic inflammation intestinal epithelial derived netrin-1 suppresses CD4 Th1 T cell trafficking through an A2B adenosine receptor mediated signaling pathway. A novel genetic model for epithelial specific deletion of netrin-1 will assist in elucidating the functional role of endogenous netrin-1 during development of chronic intestinal inflammation. In vivo and in vitro functional assays will identif the netrin-1 signaling pathway responsible for the therapeutic effect of netrin-1 in TNFΔARE ileitis. The applicant will use the K01 mechanism to develop her knowledge of mucosal immunology and T cell biology by attending focused workshops and conferences. The committee she has assembled to assist her along with her participation in practical courses will educate her in the technology she needs to perform her analyses of CD4 T cell function. The goal of the proposed studies is to use a genetic and pharmacologic approach to determine the role of netrin-1 in chronic intestinal inflammation as occurs in IBD. "