2016-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/643112摘要：漿狀樹突細胞（pDCs)是在發炎和感染過程中能夠產生大量第一型干擾素（IFN-I)的一群特化 免疫細胞。DC包含pDC的壽命是十分短的，因此它們需要不斷的從骨髓或淋巴系的前驅細胞去更 新補充。雖然pDCs在正常發育的過程是十分仰賴造血細胞激素如FL和轉錄因子如及/¥(做出E2-2 蛋白）的幫助，在發炎和感染過程中控制DC發育的訊息分子仍然不清楚。我們先前的研究已經證 實Flt3配體(FL)可以使共同淋巴前驅細胞（common lymphoid progenitor, CLP)產生IFN-I，進而提 高Flt3的表達和促進CLP的生存及增殖並使它們分化為pDC。因此FL與IFN-I可以共同調節pDC 的發育。經由藥理抑制劑的篩選，我們發現Mapkl4 (做出p38a蛋白)是一個控制FL作用所引起pDC 發育的重要訊息分子，Mapk14條件式基因剔除鼠可以幫助我們進一步了解這個分子在體内pDC發 育的角色。造血幹細胞和前驅細胞（HSPCs)像是CLP都會表達各種TLR，比如TLR2、TLR4、 TLR7和TLR9，這可能暗示TLR下游的訊號傳遞可能會直接調控DC的發育。的確，TLR刺激劑， 包括Pam3CSK4，LPS，R848和CpG的給予都會改變CLP在體外發育為DC的過程，從原本促進 pDC的產生變成抑制pDC但促進cDC的生成。在一系列針對CpG的實驗結果顯示，這個效果是和 Flt3或IFN受體的反應沒有關係，反而是和TLR9的訊號傳導有關。此外，該效果在沒有STAT3 的情況下就消失了，顯示STAT3可能是TLR9下游控制cDC生成的重要分子。有趣的是，經由 TLR3、4、7去辨識的流感病毒在體外處理或在體内感染也會增強cDC生成。這些結果顯示發炎反 應或病毒感染可以直接作用於骨髓中的造血幹細胞和前驅細胞去改變DC的產生過程。因為異常 pDC的活化和IFN-I的產生會導致自體免疫疾病的發生，因此研究pDC的發育調控過程可以讓我 們利用pDC生成的抑制劑做為一種新穎的自體免疫治療策略之一。在此我們計晝的主要目標著重 在四個重要課題。1.研究FL和IFN-I訊號路徑中調控CLP常態發育為pDC的機制2.研究發炎反 應所引起的pDC和cDC發育互換的機制3.研究在發炎過程產生的pDC的功能4.研究流感病毒 感染所引起呼吸道的發炎對DC發育的影響 樹突細胞<br> Abstract: Plasmacytoid dendritic cells (pDCs) are specialized immune cells that are capable of producing large quantities of type I interferon (IFN-I) in response to inflammation or infection. DCs, including pDCs, are short-lived and, therefore, require constant replenishment from their progenitors of both myeloid and lymphoid lineages in the bone marrow (BM). Although regulation of steady-state homeostasis of pDCs is largely dependent on hematopoietic cytokines, such as Flt3 ligand (FL) and transcriptional factors, such as Tcf4 (encodes E2-2), the signal molecules dictate pDC development remain elusive. We have previously shown that IFN-I was induced by FL stimulation in common lymphoid progenitors (CLPs), facilitating theup-regulation of Flt3 receptor and enhancing survival and proliferation of CLPs and their differentiation into pDCs. Therefore, FL is able to coordinate with IFN-I to regulate pDC development from CLPs. Using pharmacological inhibitor screening, we have identified Mapk14 (encodes p38a) as one of the key mediators for controlling FL-dependent pDC development in vitro. Mapk14 conditional knockout mice will further confirm the role of this gene in pDC development in vivo. Hematopoietic stem and progenitor cells (HSPCs), including CLPs, express various TLRs, including TLR2, TLR4, TLR7 and TLR9, suggesting that TLR-mediated signaling may directly regulate the developmental program of DCs. Indeed, the administration of TLR agonists, including Pam3CSK4, LPS, R848 and CpQ in conjunction with FL in vitro altered FL-dependent DC development from CLPs by inhibiting pDCs but promoting cDC generation. A series of experiments focusing on CpG suggests that the effect was independent of signals downstream of Flt3 or IFN-I receptor but dependent on those of TLR9. Moreover, the effect was abolished in the absence of STAT3, suggesting that STAT3 might play a vital role in TLR9-dependent developmental switch to cDCs. Interestingly, treatment of influenza virus, which is recognized by TLR3, 4 and 7, in vitro or infection in vivo also decreased pDC but enhanced cDC generation. These results suggest that inflammation and/or infection may target HSPCs in the BM to remodel DC homeostasis. Moreover, we have established an immortalized HSPC (iHSPC) to facilitate a systemic investigation of the signaling events involved in pDC development in steady-state and inflammation. Since pDCs and IFN-I are associated with pathogenesis of autoimmune diseases; we hypothesize that the inhibitors of pDC development or IFN-I production may provide a strategy for therapeutic intervention of the autoimmunity. In this proposal we aim to address the following important issues. 1. To study the mechanisms for FL and IFN-I-regulated pDC development in steady-state. 2. To study the mechanisms for developmental switch of pDCs and cDCs in inflammation. 3. To study the functions of pDCs developed during inflammation. 4. To study the effects of influenza virus infection-induced airway inflammation on DC development.漿狀樹突細胞共同淋巴前驅細胞樹突細胞發育平衡發炎類鐸受體流感病毒plasmacytoid dendritic cellcommon lymphoid progenitordendritic cell homeostasisTLRinflammationinfluenza virus