The role of regulatory T cells in biliary atresia

调节性T细胞在胆道闭锁中的作用

基本信息

批准号：
8400215
负责人：
Alexander Miethke
金额：
$ 33.38万
依托单位：
CINCINNATI CHILDRENS HOSP MED CTR
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-15 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8400215
关键词：
Adoptive Transfer Age Attenuated Biliary Biliary Atresia Bilirubin Binding Biological Assay CD4 Positive T Lymphocytes CD8-Positive T-Lymphocytes CD8B1 gene CXCL10 gene CXCR3 gene Cell Differentiation process Cell Transplantation Cells Child Childhood Cholestasis Chronic Coculture Techniques Cytokine Suppression Data Defect Dendritic Cells Development Disease Down-Regulation Ductal Experimental Models Extrahepatic Frequencies Future Goals Grant Hepatic Hepatocyte Human IL2RA gene Immune Immune response Immune system Immunotherapy In Vitro Infant Inflammation Inflammatory Injury Interleukin-10 Knock-out Knowledge Left Life Link Liver Liver diseases Lymphocyte Lymphocyte Activation Macaca mulatta Measures Mediating Mediator of activation protein Membrane Molecular Mus Myelogenous NK Cell Activation Names Natural Killer Cells Neonatal Obstruction Outcome Pathogenesis Pathway interactions Phase Phenotype Positioning Attribute Predisposition Process Production Publishing Regulation Regulatory Pathway Regulatory T-Lymphocyte Reporter Reporting Research Role Rotavirus Rotavirus Infections Sampling Serum Severity of illness Site Staging T-Cell Activation T-Lymphocyte Testing Time Tissues Transgenic Mice Transplantation Up-Regulation Viral Virus Virus Diseases base bile duct biliary tract chemokine receptor cohort cytokine cytotoxic immune activation improved in vitro Assay in vivo in vivo Model injured innovation latency-associated protein liver transplantation migration mouse model neonate neutralizing antibody novel research study response trafficking translational study trend unpublished works validation studies

项目摘要

DESCRIPTION (provided by applicant): Biliary atresia (BA) is a progressive fibroinflammatory obstruction of the extrahepatic biliary tree and the most common indication for pediatric liver transplantation worldwide. It is uniquely restricted to the early neonatal period, and rotavirus (RRV) infection only causes BA in mice when injected during the first 3 days of life. We have reported that regulatory T cells (Tregs) are absent in the liver during this time period, but emerge rapidly following RRV challenge in older mice protected from RRV induced BA. In preliminary studies, we have shown that adoptive transfer of Treg-containing CD4+ cells prior to RRV inoculation constrained hepatic expansion of NK and CD8 lymphocytes and attenuated the BA phenotype, as evidenced by lower serum bilirubin levels and reduced inflammatory bile duct obstruction. Mechanistically, these changes were linked to down-regulation of B7 costimulatory molecules on hepatic myeloid dendritic cells. Adoptive transfer experiments with CD4 cells lacking the chemokine receptor CXCR3 indicated a critical role for local positioning of Tregs in control of hepatic immune responses. In samples of infants with BA, we found trends towards increased production of pro-inflammatory cytokines in circulating T-lymphocytes, up-regulation of B7 molecules on hepatic myeloid dendritic cells, and increased frequency of circulating Tregs lacking expression of CXCR3 compared with age- matched controls without liver injury. Based on these data we propose the overarching hypothesis that Tregs protect from neonatal bile duct injury through local control of effector lymphocyte activation. This hypothesis will be tested in three overlapping specific aims: 1) to determine the mechanisms by which Tregs constrain bile duct injury, 2) to identify pathways of immune regulation by Tregs in BA, and 3) to elucidate molecular determinants for Treg trafficking to the site of inflammation in BA. For aim 1, the effects of adoptive transfer of Treg/CD4+ cells on cytotoxic activity of NK cells and differentiation of T-lymphocytes will be examined in murine BA, and Treg suppression of cytokine production in circulating T-lymphocytes will be studied in infants with BA and in healthy controls. For aim 2, the roles of dendritic cells, TGF? and IL10 as cellular and cytokine mediators of Treg suppression will be investigated using knockout and reporter transgenic mice, cell transplantation experiments, cytokine neutralizing antibodies, and co-culture assays measuring the stimulatory capacity of dendritic cells. Preliminary results of up-regulation of B7-molecules on hepatic dendritic cells in infants with BA will be validated in a larger cohort. For aim 3, the influence of CXCR3 on Treg-migration to the liver will be elucidated in adoptive transfer experiments and by determining the functional profile of circulating and hepatic Tregs in BA subjects and controls. Collectively, the complementary studies in mice and tissue of infants with BA will identify key regulatory pathways by which Tregs control pathogenesis of disease, guide future therapies to block the progression of biliary injury, and improve long term outcomes in children. PUBLIC HEALTH RELEVANCE: Biliary atresia is the number one indication for liver transplantation in children and its cause is unknown. This grant proposes to investigate whether a low number of master immune cells (named regulatory T cells) during the neonatal period predisposes to uncontrolled activation of lymphocytes injuring neonatal bile ducts. The complementary studies in the mouse model and in human samples will advance our knowledge of the disease and facilitate the development of novel non-transplant treatment options for biliary atresia.

描述（由申请人提供）：胆道闭锁（BA）是肝外胆管树的进行性纤维炎性阻塞，是全世界小儿肝移植最常见的适应症。它仅局限于新生儿早期，轮状病毒 (RRV) 感染仅在小鼠出生后 3 天内注射时才会引起 BA。我们报道说，调节性 T 细胞 (Treg) 在这段时间内在肝脏中不存在，但在受到 RRV 诱导的 BA 保护的老年小鼠中，在 RRV 攻击后迅速出现。在初步研究中，我们表明，在接种 RRV 之前过继转移含有 Treg 的 CD4+ 细胞可限制 NK 和 CD8 淋巴细胞的肝脏扩张，并减弱 BA 表型，血清胆红素水平降低和炎症性胆管阻塞减少就证明了这一点。从机制上讲，这些变化与肝髓系树突状细胞上 B7 共刺激分子的下调有关。对缺乏趋化因子受体 CXCR3 的 CD4 细胞进行的过继转移实验表明，Treg 的局部定位在控制肝脏免疫反应中发挥着关键作用。在患有 BA 的婴儿样本中，我们发现与年龄相比，循环 T 淋巴细胞中促炎细胞因子的产生增加、肝髓系树突状细胞上的 B7 分子上调以及缺乏 CXCR3 表达的循环 Tregs 频率增加的趋势。匹配的对照无肝损伤。基于这些数据，我们提出了一个总体假设：Tregs 通过局部控制效应淋巴细胞激活来防止新生儿胆管损伤。该假设将在三个重叠的具体目标中进行测试：1）确定 Tregs 限制胆管损伤的机制，2）确定 BA 中 Tregs 的免疫调节途径，3）阐明 Treg 运输至胆管损伤的分子决定因素。 BA 的炎症部位。对于目标 1，将在小鼠 BA 中检查 Treg/CD4+ 细胞过继转移对 NK 细胞的细胞毒活性和 T 淋巴细胞分化的影响，并将在患有以下疾病的婴儿中研究 Treg 对循环 T 淋巴细胞中细胞因子产生的抑制BA 和健康对照。对于目标 2，树突状细胞、TGF 的作用？将使用敲除和报告基因转基因小鼠、细胞移植实验、细胞因子中和抗体以及测量树突状细胞刺激能力的共培养测定来研究IL10和IL10作为Treg抑制的细胞和细胞因子介导物。 BA 婴儿肝树突状细胞上 B7 分子上调的初步结果将在更大的队列中得到验证。对于目标 3，CXCR3 对 Treg 迁移至肝脏的影响将在过继转移实验中并通过确定 BA 受试者和对照中循环和肝脏 Tregs 的功能概况来阐明。总的来说，对患有 BA 的小鼠和婴儿组织进行的补充研究将确定 Tregs 控制疾病发病机制的关键调节途径，指导未来的治疗以阻止胆道损伤的进展，并改善儿童的长期结果。公共卫生相关性：胆道闭锁是儿童肝移植的首要适应症，其原因尚不清楚。该资助计划调查新生儿期主免疫细胞（称为调节性 T 细胞）数量较少是否容易导致淋巴细胞不受控制的激活，从而损伤新生儿胆管。小鼠模型和人类样本的补充研究将增进我们对该疾病的了解，并促进开发针对胆道闭锁的新型非移植治疗方案。