Mechanistically linking skeletogenesis and hematopoiesis

描述（由申请方提供）：本提案将描述软骨内骨化（其中肥大软骨被骨和骨髓替代）与功能性免疫系统发育之间的联系。为此，将使用胶原X转基因（Tg）和基因敲除小鼠（KO）小鼠，因为疾病表型涉及生长板缺陷，导致骨髓环境改变和异常造血。有人提出，胶原蛋白X和其他基质分子，如糖胺聚糖和硫酸乙酰肝素蛋白聚糖，提供了一个结构网络，隔离细胞因子在肥大的软骨，和破坏这个网络可能会导致不适当的信号在生长板/骨髓交界处，导致改变骨髓环境和造血缺陷。为了测试这一点，1）来自胶原X小鼠的骨髓驻留细胞（例如基质细胞、肥大软骨和/或成骨细胞）在疾病表型中的参与将用骨髓移植来证实，2）此外，将测定胶原X小鼠骨髓环境对体外造血的支持，将测试淋巴细胞的功能，并单独测定骨髓驻留细胞支持造血的能力。3)最后，将探讨一种机制，通过实时RT-PCR的生长板和骨髓组织从胶原X小鼠的异常细胞因子的表达，由于去分解的肥大网络，改变造血。由此产生的数据可以阐明造血骨髓是如何建立的，以及哪些骨骼缺陷可能导致骨髓改变和造血疾病。了解骨骼发育和造血之间的关系可能会揭示哪些骨骼缺陷导致骨髓改变，导致造血功能障碍和免疫功能受损，如骨髓衰竭和免疫功能障碍（例如再生障碍性贫血，类风湿性关节炎），自身免疫，以及某些癌症（例如白血病，淋巴瘤）。

DESCRIPTION (provided by applicant): This proposal will characterize the link between endochondral ossification, where hypertrophic cartilage is replaced by bone and marrow, and the development of a functional immune system. To do this, collagen X transgenic (Tg) and knock-out mice (KO) mice will be used since the disease phenotype involves growth plate defects, which lead to an altered marrow environment and aberrant hematopoiesis. It is proposed that collagen X and other matrix molecules, e.g. glycosaminoglycans and heparan sulfate proteoglycans, provides a structural network that sequesters cytokines in hypertrophic cartilage, and disruption of this network may cause inappropriate signaling at the growth plate/marrow junction leading to an altered marrow environment and defective hematopoiesis. To test this, 1) The involvement of the bone marrow resident cells, e.g. stromal cells, hypertrophic cartilage, and/or osteoblasts, from the collagen X mice in the disease phenotype will be confirmed with bone marrow transplants, 2) Further, the collagen X mouse marrow environment will be assayed for support of hematopoiesis in vitro, function of lymphocytes will be tested, and the marrow resident cells will be assayed individually for the ability to support hematopoiesis. 3) Finally, a mechanism will be explored that links aberrant cytokine expression, due to decompartmentalization of the hypertrophic network, to altered hematopoiesis via real-time RT-PCR of growth plate and marrow tissue from collagen X mice. Resulting data may elucidate how a hematopoietic marrow is established, and which skeletal defects might contribute to marrow alterations and hematopoietic disorders. Understanding the relationship between skeletal development and hematopoiesis may reveal which skeletal defects contribute to marrow alterations, leading to hematopoietic disorders and impaired immunity, such as bone marrow failure and immune dysfunction (e.g. aplastic anemia, rheumatoid arthritis), autoimmunity, as well as certain cancers (e.g. leukemia, lymphoma).