Mechanistically linking skeletogenesis and hematopoiesis

描述(申请人提供)：这项提案将描述软骨内骨化和功能性免疫系统发展之间的联系。软骨内骨化是指肥大的软骨被骨和骨髓取代。为此，将使用X型胶原转基因(TG)和基因敲除小鼠(KO)，因为这种疾病的表型涉及生长板缺陷，这会导致骨髓环境改变和异常造血。有人认为，X型胶原和其他基质分子，如糖胺多聚糖和硫酸乙酰肝素蛋白多糖，提供了一个结构网络，将细胞因子隔离在肥大的软骨中，该网络的破坏可能会导致生长板/骨髓交界处的不适当信号，导致骨髓环境改变和造血功能障碍。为了检验这一点，1)X胶原小鼠的骨髓常驻细胞，如基质细胞，肥大的软骨，和/或成骨细胞，将通过骨髓移植来证实是否参与了疾病的表型；2)进一步，X胶原小鼠的骨髓环境将被检测在体外是否支持造血，淋巴细胞的功能将被检测，并且骨髓常驻细胞将被单独检测其支持造血的能力。3)最后，通过实时RT-PCR检测X型胶原小鼠的生长板和骨髓组织，将肥大网络的分解引起的细胞因子的异常表达与造血改变联系起来的机制将被探索。由此产生的数据可能会阐明造血骨髓是如何建立的，以及哪些骨骼缺陷可能会导致骨髓改变和造血障碍。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会导致骨髓改变，导致造血障碍和免疫功能受损，如骨髓衰竭和免疫功能障碍(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(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).