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。托法替尼现在被批准用于类风湿性关节炎、银屑病关节炎和炎症性肠病。托法替尼和其他Jak抑制剂（jakinibs）也正在研究强直性脊柱炎，青少年关节炎和许多皮肤病，包括牛皮癣，斑秃和特应性皮炎。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Jakinibs可能有用的其他临床情况，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。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。在临床前模型中，我们发现用托法替尼治疗导致肾炎、皮肤炎症和自身抗体产生的改善。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。基于这些临床前研究结果，NIH临床中心与Kaplan实验室和NIIMS狼疮临床试验合作，启动了轻中度SLE临床试验。这项在30例SLE受试者中使用托法替尼（药物与安慰剂比例为2：1）的1b/2a期随机、双盲、安慰剂对照临床试验按是否存在STAT 4风险等位基因进行分层。本研究显示，与安慰剂组相比，托法替尼治疗组第56天的I型干扰素基因特征、低密度粒细胞和中性粒细胞胞外陷阱的循环水平显著降低，同时不同免疫细胞的pSTAT磷酸化水平显著降低。使用托法替尼导致托法替尼治疗患者的HDL-C和HDL颗粒数量显著增加，同时卵磷脂：胆固醇酰基转移酶（LCAT）浓度和胆固醇外排能力显著改善。与安慰剂组相比，治疗组的动脉僵硬度和内皮功能障碍有所改善。在研究结束时（托法替尼停药后4周），这些变化大多恢复至基线值。 其中一些变化与STAT 4风险等位基因的存在或不存在相关。此外，托法替尼耐受性良好，未发生SLE疾病活动性恶化、重度AE、机会性感染、血栓栓塞事件或肝功能异常。因此，在一项短期试验中，使用托法替尼可显著改善SLE患者与动脉粥样硬化加速相关的心脏代谢和免疫疾病参数。需要进行长期研究以确定托法替尼对SLE各种表现（包括心血管风险）的疗效。 为了更好地理解使用第一代和第二代jakinib的意义，特别是在炎症性肠病中，还研究了这些药物对小鼠模型中适应性和先天淋巴细胞的稳态的影响。 这项工作是与Gadina实验室合作完成的。

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 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. Tofacitinib is now approved for rheumatoid arthritis, psoriatic arthritis and inflammatory bowel disease. Tofacitinib and other Jak inhibitors (jakinibs) are also being studied in ankylosing spondylitis, juvenile arthritis, and many dermatological conditions including psoriasis, alopecia areata and atopic dermatitis. 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 appropriate candidate 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. 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. In a preclinical model, 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. Based on these preclinical findings, in collaboration with the Kaplan lab and the NIAMS Lupus Clinical Trials clinical trial in mild-moderate SLE was launched at the NIH Clinical Center. This phase 1b/2a randomized, double-blind, placebo-controlled clinical trial of using tofacitinib in 30 SLE subjects (2:1 drug to placebo ratio) was stratified by the presence or absence of STAT4 risk allele. This study showed the type I Interferon gene signature, circulating levels of low-density granulocytes and neutrophil extracellular traps significantly decreased in the tofacitinib treated group compared to the placebo group by day 56, accompanied by significant decreases in pSTAT phosphorylation of different immune cells. The use of tofacitinib resulted in a significant increase in HDL-C and HDL particle number in tofacitinib-treated patients accompanied by significant improvements in lecithin: cholesterol acyltransferase (LCAT) concentration and cholesterol efflux capacity. Arterial stiffness and endothelial dysfunction improved in the treatment group as compared to the placebo group. Most of these changes reverted towards baseline values at the end of study, 4 weeks after withdrawal of tofacitinib. Some of these changes were associated to presence or absence of STAT4 risk allele. In addition, tofacitinib was well tolerated with no worsening of SLE disease activity, no severe AEs, opportunistic infections, thromboembolic events or liver function abnormalities. Thus, in a short-term trial, use of tofacitinib resulted in significant improvements in cardiometabolic and immunologic disease parameters associated with accelerated atherosclerosis in SLE. Long-term studies are needed to determine the efficacy of tofacitinib in the various manifestations of SLE including cardiovascular risk. To better understand the implications of the use of first and second generation jakinibs, especially in inflammatory bowel disease, the effects these agents on the homeostasis of adaptive and innate lymphoid cells in murine models was also investigated. This work was done in collaboration with the Gadina laboratory.