CD38对固有免疫的影响及其机制

Protective mechanisms of the host will be initiated by the activation of TLR, including the chemotaxis and activation of immune cells. TLR4 defection always accompanied with inflammation. We have made CD38-/- mice successfully, we found that the expression of TLR4 is increased in macrophages but decreased in spleen significantly in CD38-/- mice, and obstacled B cell development always displayed in TLRmut mice. Our study aims at 1) Elucidate the effects of CD38 to the distribution and expression of TLR4 by analyze the different expression of TLR4 in organs (such as heart, liver spleen, lung, kidney, cerebrum, thymus and lymph node) and cells (such as B cell, Mψ, DC, NKC, monocyte and master cell) related to the innate immunity. 2) Reveal the effects and those key checkpoints of CD38 in cells related to innate immunity by compare the difference of their phenotype and functions in cells related to the innate immunity between WT and CD38-/- mice. 3) explore the potential effects and their mechanisms of CD38 in the inflammation reaction by compare the different reactions among WT, CD38-/- and CD38-/- TLR4mut mice after stimulated with LPS. Our study will make up the defection of our knowledge about the effects of CD38 in innate immunity, and will provide new targets for medical intervene.

TLR活化启动宿主防护机制，包括免疫细胞的趋化和激活，TLR4缺陷常伴炎性反应升高。我们已制备CD38-/-小鼠，前期研究发现CD38-/-小鼠腹腔Mψ中TLR4表达上升，脾脏中TLR4表达却显著下降，且TLR4mut小鼠B细胞发育障碍。本研究旨在1）通过比较WT和CD38-/-小鼠内脏器官(心、肝、脾、肺、肾、脑、胸腺及淋巴结)及固有免疫相关细胞(B细胞、Mψ、DC、NK细胞、单核细胞及肥大细胞)中TLR4表达的差异，阐明CD38缺陷对TLR4分布及表达的影响；2）借助分析WT和CD38-/-小鼠固有免疫细胞的表型及功能差异，揭示CD38缺陷对固有免疫细胞的影响及其节点；3）利用比较WT、CD38-/-和CD38-/- TLR4mut小鼠对LPS刺激的反应不同，探索CD38在炎症反应中的潜在作用及其机制。这方面的研究将弥补我们对CD38在固有免疫中作用认识的缺陷，为医学干预提供新的靶点。

CD38基因在心血管疾病、肿瘤及代谢性疾病中有广泛调节作用，但关于其在调节免疫细胞发育中的报道较少，且未见有关CD38基因与TLR4相关性的报道。在此项目中，我们制备了CD38-/-TLR4mut小鼠，比较了WT和CD38-/-小鼠内脏器官及固有免疫相关细胞中TLR4表达的差异，分析了WT和CD38-/-小鼠脾脏中PMN的浸润情况，研究了CD38缺陷对小鼠骨髓MC中炎性因子表达的影响，着重研究了LPS刺激前后CD38缺陷对B细胞发育、增殖及凋亡的影响及其关键节点，对小鼠骨髓及引流淋巴结中DC成熟和功能的影响及其机制，对Mψ炎性因子表达的影响，借助CD38-/-和CD38-/-TLR4-/- RAW264.7分析CD38缺陷对Mψ炎性因子表达影响的关键节点。结果表明：CD38基因缺陷1）可引起脾脏B细胞数量减少，主要与其激活TLR4通路引起B细胞凋亡增加(由26.1%升高到55.5%)相关。2）可能通过激活Sirt1通路，抑制脾脏B细胞中炎性因子TNF-α和IL-1β的表达，从而抑制B细胞发育成熟，mB细胞的比例从48.8%降至26.9%，特别是T1细胞的发育阻滞（由17.5%升为28.9%）和T1向T2的转型障碍；LPS刺激诱导的炎性反应中,Sirt1对炎性因子IL-1β的表达抑制作用更为显著。3）可促进小鼠脾脏中B细胞及其亚群中IgD的表达，但对B细胞发育周期无影响。4）激活TLR4通路引起DC发育障碍，LPS刺激作用下尤为显著，但CD38基因缺失引起的DC发育障碍与IL-1β无相关性；外周引流淋巴结DC中MHC Ⅱ表达显著下降(由50.8%降低到34%)，CD40与CD80的表达未见影响。5）激活TLR4通路引起Mψ中炎性因子TNF-α和IL-1β表达显著升高，LPS刺激后反而无显著性差异。6）显著增加小鼠脾脏中PMN浸润和Mψ的比例。7）引起脾脏MC中趋化因子MCP-1的表达显著升高。综上所述，我们的研究结果表明：CD38基因在B细胞、DC和Mψ的发育成熟中都起着重要的促进作用，TLR4信号通路的激活是CD38基因缺失引起B细胞凋亡、DC发育障碍和Mψ中炎性因子表达升高的关键节点，与炎症反应关系密切，而CD38基因缺失引起B细胞发育障碍可能与Sirt1通路激活相关。研究结果弥补了我们对CD38在固有免疫中作用认识的缺陷，为医学干预提供了新靶点。