Targeting Jak3 in the treatment of autoimmune disease

细胞因子包括调节许多类型细胞的细胞生长和分化的分泌蛋白的大家族。这些因子在调节免疫和炎症反应、调节淋巴发育和分化中特别重要。毫不奇怪，细胞因子在自身免疫性疾病如类风湿性关节炎、系统性红斑狼疮、炎症性肠病和银屑病的发病机制中至关重要。了解细胞因子作用的分子基础为免疫介导疾病的发病机制提供了重要的见解，并提供了新的治疗靶点。 我们发现了人Jak 3，这是一种通过结合常见γ链gc（IL-2、IL-4、IL-7、IL-9、IL-15和IL-21）的细胞因子进行信号传导所必需的激酶。我们发现Jak 3突变导致一种原发性免疫缺陷疾病，称为严重联合免疫缺陷（SCID）。我们已经获得了两项与靶向Jak 3相关的专利，作为一类新的免疫抑制剂/免疫调节药物的基础，并与辉瑞公司建立了合作研发协议（CRADA），以生产第一代Jak 3拮抗剂。一种化合物，托法替尼（CP 690，550），由辉瑞公司生产，并发现在临床前模型中有效。该药物在类风湿性关节炎的III期研究中进行了测试，现在已被批准用于该适应症。托法替尼也在银屑病、银屑病关节炎、强直性脊柱炎、幼年型关节炎和移植排斥中进行研究。其他几种Jak抑制剂已经开发出来，也在临床试验中。 与辉瑞的CRADA于今年更新，旨在更好地了解托法替尼和相关抑制剂的作用机制。考虑到Jakinibs可能有用的临床情况，我们认为移植物抗宿主病可能是这种药物有效的环境。 这给我们带来了一个重要的问题，因为异基因造血干细胞移植的效用通常受到移植物抗宿主病（GVHD）的限制，该问题是发病率和死亡率的重要原因。移植物抗宿主病患者表现为皮肤表现，组织学特征为界面皮炎，随后为硬皮病样变化。我们发现托法替尼给药可预防CD 8 T细胞介导的GVHD样疾病的过继转移模型。 疗效表现为全身性疾病减少和体重减轻，以及粘膜皮肤病变改善。更重要的是，托法替尼也能有效逆转已确立的疾病。在该模型中，托法替尼减少了鼠CD 8 T细胞的扩增和活化，对IL-2刺激的人CD 8 T细胞具有相似的作用。托法替尼还抑制角质形成细胞表达IFN-诱导的化学引诱物，以及角质形成细胞的IFN-诱导的细胞死亡。托法替尼可能是治疗GVHD患者中CD 8 T细胞介导的皮肤粘膜疾病的有效药物。 今年，我们还研究了Jakinibs在癌症治疗中的效用。 具体而言，我们试图确定托法替尼是否可以限制宿主对免疫毒素的反应，这可能会限制后者的疗效。 我们发现，用托法替尼（JAK抑制剂）对小鼠进行单药治疗可抑制对源自细菌蛋白假单胞菌外毒素A的免疫毒素以及对模型Ag钥孔血蓝蛋白的抗体应答。我们发现，在免疫后21天观察到两种抗原的IgG 1滴度降低了千倍。事实上，所有IgG同种型和IgM的抑制都是明显的。用胸腺非依赖性II型Ag也观察到IgG 3产生减少。机制研究显示，托法替尼治疗导致CD 127 + pro-B细胞数量减少。此外，我们观察到托法替尼治疗小鼠的生发中心B细胞较少，生发中心形成受损。由于托法替尼治疗期间仍存在正常的IG水平，因此该药物特异性降低了新生抗药抗体，从而保留了生物治疗剂（包括用作癌症治疗剂的生物治疗剂）的潜在疗效。 我们也一直在研究托法替尼对T细胞代谢的影响。T细胞活化与糖酵解代谢的转换有关。我们已经发现托法替尼抑制许多关键糖酵解酶的诱导。干扰代谢中的精氨酸调节的变化可能是Jak抑制剂作用机制的一个重要方面。 在相关研究中，我们检查了托法替尼对活化T细胞增强子景观演变的影响。 我们发现，与典型的增强子相比，托法替尼对拉伸/超级增强子具有选择性作用

Cytokines comprise a large family of secreted proteins that regulate cell growth and differentiation of many types of cells. These factors are especially important in regulating immune and inflammatory responses, regulating lymphoid development and differentiation. Not surprisingly, cytokines are critical in the pathogenesis of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease and psoriasis. Understanding the molecular basis of cytokine action provides important insights into the pathogenesis of immune-mediated disease and offers new therapeutic targets. We discovered human Jak3, a kinase essential for signaling by cytokines that bind the common gamma chain, gc (IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21). We found that mutation of Jak3 results in a primary immunodeficiency disorder termed severe combined immunodeficiency (SCID). We have received two patents related to targeting Jak3 as the basis for a new class of immunosuppressant/immunomodulatory drugs, and established a Cooperative Research and Development Agreement (CRADA) with Pfizer to generate the first-generation Jak3 antagonists. One compound, tofacitinib (CP 690,550), was produced by Pfizer and found to be effective in preclinical models. The drug was tested in Phase III studies in rheumatoid arthritis, and has now been approved for this indication. Tofacitinib is also being studied in psoriasis, psoriatic arthritis, ankylosing spondylitis, juvenile arthritis and transplant rejection. Several other Jak inhibitors have been developed and are also in clinical trials. The CRADA with Pfizer was renewed this year and was directed at better understanding the mechanisms of action of tofacitinib and related inhibitors. In considering clinical circumstances in which Jakinibs might be useful, we thought a graft-versus-host-disease might be setting in which this agent would be effective. This struck us as an important problem in that the utility of allogeneic hematopoietic stem cell transplantation is often limited by graft-versus-host disease (GVHD), a problem which is a significant cause of morbidity and mortality. Patients with GVHD exhibit cutaneous manifestations with histological features of interface dermatitis followed by scleroderma-like changes. We found that administration of tofacitinib prevented an adoptive transfer model of GVHD-like disease mediated by CD8 T cells. Efficacy was manifested by reduction in systemic disease and weight loss, as well as amelioration of mucocutaneous lesions. More importantly, tofacitinib was also effective in reversing established disease. Tofacitinib diminished the expansion and activation of murine CD8 T cells in this model, and had similar effects on IL-2-stimulated human CD8 T cells. Tofacitinib also inhibited the expression of IFN-γ-inducible chemoattractants by keratinocytes, and IFN-γ-inducible cell death of keratinocytes. Tofacitinib may be an effective drug for treatment against CD8 T-cell-mediated mucocutaneous diseases in patients with GVHD. This year we also investigated the utility of Jakinibs in the setting of cancer therapy. Specifically, we sought to determine whether tofacitinb could limit the host response to immunotoxins, which can limit the efficacy of the latter. We found that monotherapy of mice with tofacitinib (the JAK inhibitor) quells antibody responses to an immunotoxin derived from the bacterial protein Pseudomonas exotoxin A, as well as to the model Ag keyhole limpet hemocyanin. We found that thousand-fold reductions in IgG1 titers to both Ags were observed 21 d post immunization. In fact, suppression was evident for all IgG isotypes and IgM. A reduction in IgG3 production was also noted with a thymus-independent type II Ag. Mechanistic investigations revealed that tofacitinib treatment led to reduced numbers of CD127+ pro-B cells. Furthermore, we observed fewer germinal center B cells and the impaired formation of germinal centers of mice treated with tofacitinib. Because normal Ig levels were still present during tofacitinib treatment, this agent specifically reduced de novo anti-drug Abs, thus preserving the potential efficacy of biological therapeutics, including those used as cancer therapeutics. We have also been studying the effects of tofacitinib on T cell metabolism. T cell activation is associated with a switch to glycolytic metabolism. We have found that tofacitinib inhibits the induction of many key glycolytic enzymes. The interference with cytokine-regulated changes in metabolism may be an important aspect of the mechanism of action of Jak inhibitors. In related studies, we examined the effect of tofacitinib on the evolving enhancer landscapes of activated T cells. We found that tofacitinib has a selective effect on stretch/super enhancers compared to typical enhancers