Regulation of Immune Responses in Humans and Non-Human Primates

项目I：正常人固有层淋巴细胞 未刺激的细胞凋亡明显增加(与 外周血淋巴细胞)以及增强的细胞凋亡 通过CD2激活途径进行刺激。这张CD2 途径诱导的细胞凋亡下调细胞扩张和 细胞因子的产生，从而保护生物体免受 潜在的有害反应。在之前的研究中，我们证明了 克罗恩病患者的固有层T细胞 溃疡性结肠炎表现为异常增殖和细胞因子 制作。因此，确定这些细胞是否 也表现出异常的细胞凋亡模式。我们找到了那片薄片 克罗恩病患者固有层淋巴细胞显示缺陷 CD2途径诱导细胞凋亡。此外，我们还展示了 克罗恩病固有层T细胞尽管表达 相当数量的细胞表面Fas，对 Fas介导的细胞凋亡与对照细胞相比。最后，我们 证实克罗恩？S病固有层淋巴细胞 CD2信号转导通路中Bcl2的表达增强 非刺激性T细胞培养中的刺激和升高的Bc l-2水平 细胞。因此，这些研究证实了发炎椎板中的T细胞 克罗恩病患者的固有动脉明显减少 CD2途径诱导细胞凋亡，并上调Bcl2水平。这些 这些变化很可能是慢性炎症和 可能会加重IBD患者的病情。项目II：慢性 在几种动物模型中的肠道炎症已经被证明是 由IL-12驱动的Th1 T细胞介导。这些发现引导我们 炎症性疾病患者IL-12功能及信号转导的研究 肠道疾病。在最初的研究中，我们发现CD40L+ 干扰素-γ刺激的巨噬细胞固有层 克罗恩病(CD)的患者，但不是来自 溃疡性结肠炎(UC)产生的IL-12水平显著升高 P70与对照巨噬细胞相比。在进一步的研究中，我们 CD患者外周血中的CD4+T细胞不是UC患者 表现出高水平的IL-12Rβ-2链和核内STAT-4 表情。最后，我们展示了STAT-4的下调 一种反义寡核苷酸显著降低CD4+T细胞干扰素- 以Cd为单位的伽马生产。总而言之，这些数据表明一个关键的 IL-12在CD和CD不同免疫发病机制中的作用 UC：而CD中高水平的IL-12会导致 UC中产生干扰素-γ的Th1细胞，低水平的IL-12有利于 产生Th2型细胞因子的T细胞。因此， IL-12/STAT-4通路的激活是 克罗恩病发病机制可能是一种 作为治疗干预的诱人靶点。

Project I: Normal human lamina propria lymphocyte manifest increased unstimulated apoptosis (when compared to peripheral lymphocytes) as well as enhanced apoptosis following stimulation via the CD2-activation pathway. This CD2 pathway-induced apoptosis downregulates cell expansion and cytokine production and thus protects the organisms from potentially harmful responses. In previous studies we demonstrated that lamina propria T cells from patients with Crohn's disease and ulcerative colitis manifest abnormal proliferation and cytokine production. It was therefore of interest to determine if such cells also exhibited abnormal patterns of apoptosis. We found that lamina propria lymphocytes of Crohn's disease patients showed defective CD2-pathway induced apoptosis. In addition, we showed that Crohn's disease lamina propria T cells although expressing comparable amount of cell surface Fas, are less sensitive to Fas-mediated apoptosis as compared to control cells. Finally, we demonstrated that Crohn?s disease lamina propria lymphocytes manifest increased expression of Bcl-2 following CD2-pathway stimulation and elevated Bcl-2 levels in cultures of unstimulated T cells. These studies thus establish that T cells in the inflamed lamina propria of Crohn's disease patients manifest decreased CD2-pathway-induced apoptosis and elevated Bcl-2 levels. These changes are likely to be secondary to the chronic inflammation and may aggravate disease in patients with IBD. Project II: Chronic intestinal inflammation in several animal models has been shown to be mediated by IL-12-driven Th1 T cells. These findings led us to evaluate IL-12 function and signaling in patients with inflammatory bowel diseases. In initial studies we showed that CD40L plus IFN-gamma-stimulated lamina propria (LP) macrophages from patients with Crohn's disease (CD) but not from patients with ulcerative colitis (UC) produce significantly higher levels of IL-12 p70 as compared to control macrophages. In further studies we demonstrated that CD4+ T cells from CD but not UC patients exhibit high levels of IL-12R Beta-2 chain and intranuclear STAT-4 expression. Finally, we showed that down-regulation of STAT-4 by an antisense oligonucleotide strikingly reduced CD4+ T cell IFN- gamma production in CD. In summary, the data suggest a critical role for IL-12 in the differential immunopathogenesis of CD and UC: whereas high levels of IL-12 in CD lead to generation of IFN-gamma-producing Th1 cells, low IL-12 levels in UC favors production of T cells producing Th2 type cytokines. Thus, activation of the IL-12/STAT-4 pathway emerges as a central mechanism in the pathogenesis of Crohn's disease that could be an attractive target for therapeutic intervention.