Targeting Janus kinases 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以及调节淋巴发育和分化中特别重要。毫不奇怪，细胞因子在许多自身免疫性疾病如类风湿性关节炎、SLE、IBD和银屑病的发病机制中是至关重要的。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拮抗剂。一种化合物，托法替尼，是由辉瑞公司开发的，并发现在临床前模型中有效。这种药物在类风湿性关节炎中进行了测试，现在已经被批准用于这种适应症。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、IBD和各种皮肤病中进行研究。其他几种Jakinibs已经开发出来，也在临床试验中，包括后期关键试验。 与辉瑞的CRADA已更新，旨在更好地了解托法替尼和相关抑制剂的作用机制。考虑到在其他临床情况下Jakinibs可能有用，我们认为SLE可能是这类药物的合适候选者。许多影响先天免疫和适应性免疫的细胞因子被认为有助于SLE的免疫发病机制，包括干扰素IL-6、IL-21和其他干扰素。这些细胞因子的作用都被第一代Jakinibs（如托法替尼）阻断。此外，SLE患者的免疫细胞失调也与过早的血管损伤有关。到目前为止，没有药物已被证明针对疾病活动和增加SLE心血管风险。因此，我们着手评估托法替尼是否可能在免疫细胞功能障碍和血管损伤方面对SLE有用。我们发现，托法替尼治疗可改善肾炎、皮肤炎症和自身抗体产生。此外，托法替尼治疗显著降低了相关细胞因子的血清水平。托法替尼还调节中性粒细胞功能障碍和内皮异常。因此，我们得出结论，托法替尼可以调节小鼠狼疮的先天性和适应性免疫应答，并改善血管功能。这些结果表明，JAKinibs有可能有益于治疗SLE及其相关的人类血管损伤。基于这些有利的发现，我们已经在NIH临床中心开始了托法替尼治疗轻中度SLE的临床试验。 在癌症的相关工作中，我们与Jakinib合作治疗成人T细胞白血病（ATL），这是一种由HTLV 1感染引起的疾病，与Jak/STAT通路的组成性激活相关。这是一个重要的未满足的需求，因为目前还没有针对ATL的治愈性疗法。HTLV-1编码的蛋白Tax（来自X基因区域的反式激活因子）激活自分泌/旁分泌白细胞介素-2（IL-2）、IL-9和IL-15的产生，导致JAK/STAT信号放大。选择性Jakininb ruxolitinib与超过450种潜在的治疗药物结合进行了高通量矩阵筛选，Bcl-2/Bcl-xL抑制剂navitoclax被确定为多组分治疗的强有力候选者。Ruxolitinib和navitoclax独立地表现出适度的抗肿瘤疗效，而联合用药在ATL小鼠模型中显著降低了肿瘤负荷并延长了生存期。这些研究为在郁积/慢性ATL患者中使用抑制JAK信号传导和抗凋亡蛋白Bcl-xL的药物组合进行治疗试验提供了支持。 在致力于更好地理解托法替尼作用机制的相关研究中，我们检查了其对活化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，托法替尼对超级增强子具有选择性作用。 最后，我们与外部研究人员合作，以确定影响Th 17细胞的新的潜在靶点。

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, and regulating lymphoid development and differentiation. Not surprisingly, cytokines are critical in the pathogenesis of many autoimmune diseases such as rheumatoid arthritis, SLE, IBD 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 Jak antagonists. One compound, tofacitinib, was developed by Pfizer and found to be effective in preclinical models. The drug was tested in rheumatoid arthritis, and has now been approved for this indication. Tofacitinib is also being studied in psoriasis, psoriatic arthritis, ankylosing spondylitis, juvenile arthritis, IBD and various dermatological conditions. Several other Jakinibs have been developed and are also in clinical trials, including late phase pivotal trials. The CRADA with Pfizer was renewed and is directed at better understanding the mechanisms of action of tofacitinib and related inhibitors. In considering other clinical circumstances in which Jakinibs might be useful, we considered that SLE might be an appropriatecandidate for this class of drugs. A number of cytokines that impact both innate and adaptive immunity have been suggested to contribute to the immunopathogenesis of SLE, including interferons IL-6, IL-21, and other interferons. The action of these cytokines are all blocked by first generation Jakinibs like tofacitinib. In addition, immune cell dysregulation in SLE is also associated with premature vascular damage. To date, no drug has proven to target both disease activity and enhanced cardiovascular risk in SLE. We therefore set out to assess whether tofacitinib might have utility in SLE in terms of both immune cell dysfunction and vascular damage. We found that treatment with tofacitinib led to improvement in nephritis, skin inflammation, and autoantibody production. In addition, tofacitinib treatment significantly reduced serum levels of relevant cytokines. Tofacitinib also modulated neutrophil dysfunction and endothelial abnormalities. Thus, we concluded that tofacitinib can modulate the innate and adaptive immune responses in murine lupus and improve vascular function. These results indicate that JAKinibs have the potential to be beneficial in treating SLE and its associated vascular damage in humans. Based on these favorable findings, we have begun a clinical trial of tofacitinib in mild-moderate SLE at the NIH Clinical Center. In related work in cancer, we collaborated on work with a Jakinib in Adult T-cell leukemia (ATL), a disease caused by infection with HTLV1 associated with constitutive activation of the Jak/STAT pathway. This is an important unmet need as presently there is no curative therapy for ATL. HTLV-1-encoded protein Tax (transactivator from the X-gene region) activates autocrine/paracrine interleukin-2 (IL-2), IL-9, and IL-15 production, resulting in amplified JAK/STAT signaling. The selective Jakininb ruxolitinib was examined in a high-throughput matrix screen combined with greater than 450 potential therapeutic agents, and Bcl-2/Bcl-xL inhibitor navitoclax was identified as a strong candidate for multicomponent therapy. Ruxolitinib and navitoclax independently demonstrated modest antitumor efficacy, whereas the combination dramatically lowered tumor burden and prolonged survival in an ATL murine model. These studies provide support for a therapeutic trial in patients with smoldering/chronic ATL using a drug combination that inhibits JAK signaling and antiapoptotic protein Bcl-xL. In related studies, devoted to better understanding the mechanism of action of tofacitinib, we examined its effect on the evolving enhancer landscapes of activated T cells. We found that tofacitinib has a selective effect on super-enhancers compared to typical enhancers. Finally, we collaborated with external investigators to identify new potential targets that affect Th17 cells.