PATHOGENESIS AND TREATMENT OF APLASTIC ANEMIA

再生障碍性贫血的发病机制和治疗

• 批准号: 6109223
• 负责人: Neal S Young
• 金额: --
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6109223
• 关键词: aplastic anemia; artificial immunosuppression; autoimmune disorder; bone marrow disorder; clinical research; cytotoxic T lymphocyte; gene targeting; hematopoiesis; hematopoietic stem cells; hepatitis; histocompatibility typing; human subject; human therapy evaluation; immunohematology; lymphokines; paroxysmal nocturnal hemoglobinuria; phosphatidylinositols; tissue /cell culture

Aplastic anemia (AA) and other types of bone marrow failure have clinical and laboratory features consistent with an autoimmune pathophysiology, with a diversity of inciting antigens, including viruses, chemicals, and drugs. Whatever its specific etiology, a majority of patients respond with hematologic improvement after immunosuppressive therapies. One important clinical feature of AA is its evolution, sometimes years after normalization of blood counts, to other hematologic diseases such as paroxysmal nocturnal hemoglobinuria (PNH), which derive from clones of hematopoietic stem cells. Our laboratory studies have focused on the immune pathophysiology of AA, identification of a viral antigen, and the mechanism of late clonal evolution. Studies of etiology have continued to focus on an unknown hepatitis virus in the post-hepatitis AA syndrome (see Z01 HL 02319-14 HB). Current studies of the immune system's role in bone marrow suppression have focused on gamma-interferon, a lymphokine that inhibits hematopoiesis in vitro and in vivo. We have established an animal model for both AA and transfusion-associated graft-versus-host disease. A congenic mouse strain is employed; lymph node cells from an F1 hybrid are injected into the parental strain, where they rapidly induce bone marrow destruction due to major histocompatibility antigen differences. In this model, both helper and cytotoxic lymphocytes are required, gamma-interferon is produced, and bone marrow destruction is severe. We have established that anti-lymphocyte globulin (ATG) as well as cyclosporine ameliorate disease; anti-gamma-interferon monoclonal antibodies also prevent death and severe blood count depression, establishing for the first time an effector role for this lymphokine in immune marrow destruction. We have measured gamma-interferon in circulating peripheral blood cells in patients with AA using flow cytometry; the presence of these cells appears to correlate with the rapidity and extent of response to immunosuppressive therapy. Intracellular cytokine measurements are also the basis for TH1/TH2 and TC1/TC2 shifts as a result of in vitro treatments. While ATG does not appear to immunomodulate the character of the immune response, cyclosporine, various androgen preparations, and growth factor combinations in vitro and, in the latter case, also in vivo in normal volunteers after the TH1/TH2 immune response in favor of the TH2 component. These results are suggestive of a novel mechanism of action for these various therapeutic agents. Studies of hematopoiesis in vitro have shown that in inhibition of apoptosis by blockade of the caspase pathway is involved in lymphocyte destruction in acquired immunodeficiency syndrome, and ICE blockade in vitro may be useful to expand primitive hematopoietic stem cell numbers in tissue culture. In studies of late clonal disease following successful treatment of AA, we have focused on PNH. Previously, we established that absence of glycophosphoinositol-anchored proteins conferred marked resistance on natural killer cell cytolysis of a lymphoid cell line target; these experiments have been expanded to a hematopoietic target, paired K562 cells that lack or express glycophosphoinositol-anchored proteins. Current studies are directed to identification of the precise protein(s) involved in this interaction. We also have developed a sensitive and simple method for the detection of glycophosphoinositol-anchored proteins on hematopoietic cells from patient material, utilizing two color flow cytometry of polymorphonuclear cells. In studies of patient material we have established that approximately 20% of patients with AA present with evidence of a PNH clone and that this number is stable for several years. In addition, PNH clones are not observed in non-immune forms of bone marrow failure, such as after bone marrow transplantation or cancer chemotherapy, nor does PNH develop as a result of ATG treatment for renal allograft rejection. However, a proportion of patients with myelodysplasia also show evidence of a PNH clone, and for these cases such cells are highly predictive of response to immunosuppressive therapy. Our results are consistent with the hypothesis that PNH represents an escape mechanism in immune-mediated bone marrow failure, and that two steps are required for the development of PNH. Finally, our active clinical program continues. In the area of AA, we have initiated a randomized, cross-over design trial to compare ATG with high dose cyclophosphamide. Approximately 15 patients have been entered into this protocol with hematologic responses observed in about 70% in each arm. Long-term evaluation and larger numbers of patients will be required to determine whether cytotoxic chemotherapy can prevent relapse and the late evolution to clonal hematologic diseases.

性贫血（AA）和其他类型的骨头 骨髓衰竭具有临床和实验室特征与 自身免疫性病理生理学，多种煽动 抗原，包括病毒，化学物质和药物。不管它是什么 特定的病因，大多数患者对血液学反应 免疫抑制疗法后的改善。一个重要 AA的临床特征是其进化，有时是几年后 血液计数的归一化，其他血液学疾病此类疾病 作为阵发性夜间血红蛋白尿（PNH），源自 造血干细胞的克隆。我们的实验室研究有 专注于AA的免疫病理生理学，鉴定 病毒抗原和后期克隆进化的机制。研究 病因继续关注未知的肝炎病毒 肝炎后AA综合征（请参阅Z01 HL 02319-14 HB）。 当前对免疫系统在骨髓中作用的研究 抑制重点是伽马互换，这是一种淋巴细胞因子 在体外和体内抑制造血。我们已经建立了 AA和输血相关的动物模型 移植物与宿主病。使用先天小鼠菌株； 将F1杂种的淋巴结细胞注入父母 应变，它们迅速诱导骨髓破坏 主要的组织相容性抗原差异。在这个模型中，两者都 需要助手和细胞毒性淋巴细胞，γ互换为 产生，骨髓破坏很严重。我们有 确定抗淋巴细胞球蛋白（ATG）以及 环孢菌素改善疾病；抗γ互换单克隆 抗体还可以预防死亡和严重的血液计数抑郁症， 首次确定该淋巴因子在 免疫骨髓破坏。我们测量了伽马互换 在使用流量的患者中循环的外周血细胞中 细胞仪；这些细胞的存在似乎与 对免疫抑制治疗的快速和反应程度。 细胞内细胞因子测量也是TH1/TH2的基础 由于体外治疗，TC1/TC2移动。 atg 似乎没有免疫调节免疫的特征 反应，环孢菌素，各种雄激素制剂和生长 在体外的因子组合，在后一种情况下，在体内也在体内 TH1/TH2免疫反应后的正常志愿者有利于 TH2组件。这些结果暗示着小说 这些各种治疗剂的作用机理。研究 体外造血的表明，抑制细胞凋亡 caspase途径的封锁涉及淋巴细胞 获得的免疫缺陷综合征和ICE的破坏 体外封锁可能有助于扩展原始造血 组织培养中的干细胞数。在晚期克隆疾病的研究中 成功治疗AA后，我们专注于PNH。 以前，我们确定了 糖磷酸糖脂锚定的蛋白赋予了标记 淋巴样细胞系的天然杀伤细胞胞解的抗性 目标;这些实验已扩展到造血 目标，配对缺乏或表达的K562单元 糖磷酸糖脂锚定蛋白。当前的研究是 致力于确定与此相关的精确蛋白质 相互作用。我们还开发了一种敏感而简单的方法 为了检测糖磷酸肌醇锚定的蛋白 利用两种颜色流的患者材料的造血细胞 多形核细胞的细胞仪。在对患者材料的研究中 我们已经确定大约20％的AA患者 存在PNH克隆的证据，并且该数字稳定 几年。另外，在 骨髓衰竭的非免疫形式，例如骨后 骨髓移植或癌症化疗，PNH也不 由于ATG治疗肾脏同种异体移植排斥而发展。 但是，一部分骨髓增生的患者也表明 PNH克隆的证据，在这些情况下，这些细胞高度很高 预测对免疫抑制治疗的反应。我们的结果 与PNH代表逃生的假设一致 免疫介导的骨髓衰竭的机制，这两个 开发PNH需要步骤。最后，我们的活跃 临床计划仍在继续。在AA地区，我们发起了 随机，交叉设计试验，以对ATG进行比较 剂量环磷酰胺。大约有15位患者 进入该方案，并在 每个手臂约为70％。长期评估和更多数量 将需要患者确定是否细胞毒性 化学疗法可以防止复发和晚期发展为克隆 血液学疾病。