移植后骨髓MSC维持B细胞稳态在cGVHD发生中的作用及机理研究

B-cell homeostasis in chronic GVHD after allogeneic stem cell transplantation is gaining more and more attentions in recent years. However, the reason and the mechanism of aberrant B-cell homeostasis are unkown. The ontogeny and homeostasis of B cells depend on the bone marrow microenvironment in which MSC is a main cell of stromal cells and plays an important role in the ontogeny and homeostasis of B cells. MSC becomes a research hotspot in HSCT because it can modulate immunity and support hematopoiesis. Studies show that radiation and chemotherapy pre-transplantation and aGVHD post-transplantation might cause damage to stromal cells, which is associated with the development of cGVHD.Our previous research showed that MSC derived from bone marrow of a third-party donor had therapeutic effect on cGVHD by reducing BAFF and restoring B cell homeostasis. Based on these finding, we propose that MSC abnormity of cGVHD patients is associated with aberrant B cell homeostasis and the development of cGVHD. To test this hypothesis, we will explore the changes of bone marrow microenvironment, MSC, ontogeny and homeostasis of B cell; and the effects of MSC on the bone marrow microenvironment, the ontogeny and homostasis of B cells in cGVHD patients and animal models.These studies will show whether the MSC is abnormal in cGVHD patients and the effects that MSC has on the bone marrow microvironment,the B cell ontogeny and homeostasis and cGVHD.The mechanism of that is also explored in these studies.And these studies will provide new scientific basis for developing novel therapy for cGVHD.

近年移植后B细胞稳态在cGVHD中受到关注，但致B细胞稳态失平衡原因及机理知道甚少。B细胞发育与稳态依赖骨髓微环境，MSC是骨髓微环境中重要基质细胞，对B细胞发育与稳态起重要作用，因他具有免疫调节和支持造血成为HSCT研究热点。研究表明移植前放化疗和移植后aGVHD对基质细胞损伤与cGVHD相关，我们前期研究表明第三方骨髓MSC通过降低cGVHD病人BAFF和恢复B细胞稳态而发挥治疗作用。基于这些我们提出cGVHD病人存在骨髓MSC异常是导致B细胞稳态失平衡和cGVHD发生的假说。为验证假说，本项目在cGVHD病人及动物模型中研究：cGVHD骨髓微环境、MSC和B细胞发育与稳态变化；MSC对骨髓微环境、B细胞发育与稳态及cGVHD的影响。通过这项研究揭示：cGVHD病人骨髓MSC是否存在异常；MSC对骨髓微环境、B细胞发育与稳态和cGVHD影响和机理；为MSC防治cGVHD提供理论依据。

近年移植后B细胞稳态在cGVHD中受到关注，但致B细胞稳态失平衡原因及机理知道甚少。B细胞发育与稳态依赖骨髓微环境，MSC是骨髓微环境中重要基质细胞，对B细胞发育与稳态起重要作用，因他具有免疫调节和支持造血成为HSCT研究热点。我们通过对cGVHD病人和小鼠模型的骨髓微环境、B细胞发育与稳态、MSC对骨髓微环境和B细胞发育与稳态及在cGVHD发生与发展中的作用和机理等研究发现：1)cGVHD的患者骨髓MSC由于Wnt通路的异常激活而出现功能的异常。而MSC功能异常是cGVHD患者骨髓成纤维化的重要原因之一。2)同时，我们发现cGVHD患者自身抗体检出率明显高于未发生GVHD组，中、重度cGVHD患者抗Ro52抗体检出率明显高于轻度cGVHD患者和无cGVHD患者。证实cGVHD患者体内存在B细胞功能的异常和稳态的失衡。3)进一步研究发现MSC通过降低血浆BAFF水平和增加外周B细胞BAFF-R的表达以及改善记忆B淋巴细胞的频率和数量从而治疗cGVHD。4)并且来自cGVHD患者的CD5+B细胞在MSCs治疗后表现出增加的IL-10表达，这与T细胞产生的炎性细胞因子减少有关。从机制上讲，MSCs可以促进CD5+Breg细胞的存活和增殖，并且其分泌的吲哚胺2,3-双加氧酶部分介导了Breg细胞的作用。以上研究中部分结果在小鼠模型体内进一步得到验证。通过这些研究，为临床建立MSC防治cGVHD技术平台提供理论了依据。