Development of novel therapies of hematologic malignancies based on the functional modulation of the OX40/gp34 system

TRAF3在OX40信号转导中的作用我们以前报道过OX40信号通过TRAF2和TRAF5激活NF-κB。TRAF3也与OX40的胞浆结构域结合，但其功能相当负面地抑制了NF-κB的激活。在本研究中，我们发现TRAF3的过表达不影响NIK或IKKα介导的NF-κB的激活，并且TRAF3的N端和C端缺失突变体都具有抑制作用。这些结果表明，TRAF3抑制TRAF2和NIK通路上的NF-κB的激活，这并不一定是由于竞争抑制OX40和TRAF2的结合所致。加入抗gp34mAb可显著抑制这一反应，提示OX40/gp34系统…外周血OX40+T细胞与慢性移植物抗宿主病(CGVHD)的相关性我们研究OX40的表达是否与异基因造血干细胞移植后cGVHD的发生有关。对22例患者第100天后的外周血单核细胞进行多色流式细胞仪检测。慢性移植物抗宿主病(CGVHD)患者外周血中OX40+CD4+和OX40+CD8+T细胞的百分率均显著高于非cGVHD组。这些结果表明，动态检测OX40+T细胞对预测慢性移植物抗宿主病的发病和疗效有重要意义。OX40/gp34在ATL白血病发生中的作用。当与MMCE-gp34共培养时，ATL表达OX40，并对抗Fas诱导的细胞凋亡产生抵抗作用，而与MMCE-mock共培养则无此作用。因此，我们认为ATL细胞通过OX40/gp34系统获得有利的生存信号。gp34信号诱导血管内皮细胞产生RANTES。我们寻找在HUVECs中受gp34信号诱导或上调的基因，以确定其下游生物学事件。用重组可溶性OX40或模拟对照刺激高表达gp34的人脐静脉内皮细胞，并用基因表达阵列进行分析。我们发现CC趋化因子RANTES就是这种诱导基因之一。也就是说，gp34信号诱导人脐静脉内皮细胞RANTES在mRNA和蛋白水平上的表达，提示OX40/gp34系统与RANTES在T细胞与内皮细胞黏附和随后的外渗过程中可能存在联系。较少

Role of TRAF3 in OX40 signalingWe previously reported that OX40 signaling leads to NF-κB activation via TRAF2 and TRAF5. TRAF3 also binds to the cytoplasmic domain of OX40 but functiions rather negatively to suppress NF-κB activation. In the present study we found that overexpression of TRAF3 did not affect NIK- or IKKα-medicated NF-κB activation and that both N-terminus and C-terminus deletion mutants of TRAF3 have inhibitory effect. These results indicate that TRAF3 suppresses NF-κB activation at the pathway between TRAF2 and NIK, which is not necessarily due to competitive inhibition of binding between OX40 and TRAF2.gp34 expressed on endothelial cells provides T cells with costimulatory signalsPurified normal human CD4+ T cells did not proliferate in response to immobilized anti-CD3 mAb but showed vigorous proliferation in the coexistence of human umbilical vein endothelial cells (HUVEC). Addition of anti-gp34 mAb maredly inhibited this response, indicating that the OX40/gp34 syste … More m plays a major role in costimulation of CD4+ T cells by endothelial cells.Correlation of peripheral blood OX40+ T cells with chronic graft-versus-host disease (cGVHD)We studied whether the expression of OX40 is related to the development of cGVHD in patients who underwent allogeneic hematopoietic stem cell transplant. Peripheral blood mononuclear cells from a total of 22 patients after day 100 were subjected to multi-color flow cytometry. The percentages of both OX40+CD4+ and OX40+CD8+ T cells were significantly higher in patients with cGVHD than those without Serial analyses showed that OX40+CD4+ T cells elevated before the onset of cGVHD and at the onset closely correlated with the therapeutic response. These results indicated that serial measurement of OX40+ T cells is quite useful for predicting the onset as well as therapeutic response of cGVHD.Possible role of the OX40/gp34 in the leukemogenesis of ATLWe studied the relationship between OX40 signals and apoptosis of ATL cells. ATL constitutively express OX40 and became resistant to anti-Fas-induced apoptosis when cocultured MMCE-gp34 while coculture with MMCE-mock had no effects. Thus, it is suggested that ATL cells receive favorable signals for survival through the OX40/gp34 system.Signaling of gp34 induces vascular endothelial cells to produce RANTESWe searched for genes that were induced or upregulated by gp34 signaling in HUVECs to define its downstream biological events. HUVECs expressing high levels of gp34 were stimulated with recombinant soluble OX40 or mock control and subjected to analysis using cDNA expression arrays. We found that a CC chemokine RANTES is one of such inducible genes. Namely, gp34 signaling induces expression of RANTES at both mRNA and protein levels in HUVECs and suggest a possible link between the OX40/gp34 system and RANTES during the process of T cell adhension to endothelial cells and subsequent extravasation. Less