Mechanism of action and therapeutic utility of immunosuppressive oligonucleotide

在我的实验室进行的研究证实，表达重复TTAGGG基序的合成ODN（在哺乳动物端粒中高频出现的六聚体序列后形成模式）可以下调由广泛的TLR配体引发的炎症反应以及由多克隆激活剂和抗原诱导的T细胞反应。我们进一步证明，抑制性ODN可用于治疗以过度旺盛免疫反应为特征的疾病，包括感染性休克以及全身和器官特异性自身免疫。尽管取得了这些进展，但对抑制性ODN的细胞靶标、负责其识别/摄取的受体或其作用机制知之甚少。正在进行的研究旨在解决这些问题。我们正在使用荧光标记探针来鉴定结合和内化抑制性ODN的细胞亚群，并计划使用共聚焦显微镜跟踪它们的胞浆内定位。我们正在使用微阵列技术来鉴定基因和调控网络，使抑制性ODN破坏正在进行的炎症反应，并确定其体内免疫抑制活性的持续时间。从这些研究中获得的见解，我们计划确定负责识别TTAGGG基序的受体，这是抑制活性的关键。收集到的关于抑制性ODN的作用靶点和机制的信息将支持旨在探索其治疗效用的研究。最近的研究结果表明，全身给予抑制性ODN可以改变宿主的免疫环境，这一效应被用来降低宿主对炎症诱导的癌症的易感性。为实现这一目标，已开展了两项调查。首先，在化学诱导的小鼠皮肤癌模型中，正在评估抑制ODN的作用。初步证据表明ODN影响肿瘤细胞生长。其次，研究了抑制ODN对急性矽肺致危及生命的肺部炎症的影响。初步结果表明，ODN治疗可显著降低二氧化硅引起的死亡率和发病率。由于长期暴露于二氧化硅会显著增加肺癌的发病率，我们计划评估抑制性ODN是否可以阻断二氧化硅诱导的癌变。希望通过这些研究项目确定的CpG和/或抑制性ODN的治疗用途可以用来显著降低宿主对肿瘤发生和进展的易感性。

Studies conducted in my laboratory established that synthetic ODN expressing repetitive TTAGGG motifs (patterned after hexameric sequences present at high frequency in mammalian teleomeres) can down-regulate the inflammatory response elicited by a broad range of TLR ligands and the T cell responses induced by polyclonal activators and antigens. We further documented that suppressive ODN were useful in the treatment of diseases characterized by over-exuberant immune responses, including septic shock and both systemic and organ-specific forms of autoimmunity. Despite this progress, very little is known about the cellular targets of suppressive ODN, the receptors responsible for their recognition/uptake, or their mechanism of action. Ongoing studies are designed to resolve these questions. We are using fluorescent-labeled probes to identify the cell subsets that bind and internalize suppressive ODN, with plans to track their intracytoplasmic localization using confocal microscopy. We are using microaarray technology to identify the genes and regulatory networks that enable suppressive ODN to disrupt ongoing inflammatory responses, and determine the duration of their immuno-inhibitory activity in vivo. With the insight gained from these studies, we plan to identify the receptor(s) responsible for the recognition of the TTAGGG motif key to this suppressive activity. Information gathered on the targets and mechanism(s) of action of suppressive ODN will support studies designed to explore their therapeutic utility. Recent results suggest that systemically administered suppressive ODN can alter the hosts immune milieu, an effect being harnessed to reduce host susceptibility to inflammation-induced cancers. Two lines of investigation have been initiated to achieve this goal. First, the effect of suppressive ODN in a murine model of chemically-induced skin cancer is being evaluated. Preliminary evidence indicates that ODN impact tumor cell growth. Second, studies examining the effect of suppressive ODN on the life-threatening pulmonary inflammation induced by acute silicosis were conducted. Initial results indicate that ODN treatment significantly reduces silica-induced mortality and morbidity. As chronic exposure to silica significantly increases the incidence of lung carcinoma, we plan to evaluate whether suppressive ODN can block silica-induced carcinogenesis. It is hoped that the therapeutic uses of CpG and/or suppressive ODN identified through these research programs can be harnessed to significantly reduce host susceptibility to tumor development and progression.