干细胞治疗: 治疗肌炎和肌病的新方法

治疗肌炎和肌病的新方法

抽象的
炎症性肌病是一组以肌肉无力和炎症为特征的异质性疾病. 尽管没有标准的治疗指南, 传统治疗包括皮质类固醇和各种二线免疫抑制剂. 由于难治性疾病的治疗一直很困难, 较新的药物和方法的使用产生了不同的反应. 国际肌炎评估和临床研究标准化治疗反应标准的出现 (综合管理系统) 小组帮助研究人员以更严格的方式评估和比较临床试验结果. 静脉注射免疫球蛋白的用途 (静脉注射免疫球蛋白), 利妥昔单抗, 生物制剂，包括肿瘤坏死因子 (肿瘤坏死因子) 抑制剂, 干细胞移植, 基因治疗, 和血管闭塞阻力训练在此回顾. 随着我们对免疫学疾病发病机制的了解, 遗传的, 并且分子水平扩大, 新治疗靶点的发现有望成功治疗这些疾病.

关键词 基因治疗, 特发性炎症性肌病, 静脉注射免疫球蛋白, 新颖的方法, 利妥昔单抗, 干细胞移植
介绍
特发性炎症性肌病 (IIM) 是一组病因不明的异质性疾病，包括皮肌炎 (DM), 多发性肌炎 (下午), 包涵体肌炎 (国际商业机器公司), 以及最近描述的实体, 免疫介导的坏死性肌病. 他们的特点是临床上明显的肌肉无力, 肌酶升高, 肌电图变化, 和, 在某些情况下, 肌肉活检中细胞浸润的特征性组织学变化. 它们与肌炎特异性抗体相关，并对多种免疫抑制药物表现出不同的反应. 迄今为止，由于没有标准化的治疗方案，IIM 的治疗一直充满挑战. 国际肌炎评估和临床研究制定了标准化治疗反应标准 (综合管理系统) 小组帮助研究人员以更严格的方式评估和比较临床试验结果 [哈克等人. 2011], 缺乏证明药物疗效的大型临床试验. 此外, 这些疾病的罕见性以及疾病和治疗反应的异质性导致了复杂性.

根据临床专业知识和经验报告，治疗在很大程度上是超适应症的. 传统的一线药物仍然是皮质类固醇, 使用二线药物作为类固醇节约药物或由于缺乏持久效果. These second-line immunosuppressants include azathioprine, methotrexate, mycophenolate mofetil, leflunomide, cyclophosphamide, tacrolimus, cyclosporine, tumor necrosis factor (肿瘤坏死因子) 抑制剂, and intravenous immunoglobulin (静脉注射免疫球蛋白). We consider refractory disease to be one that fails to respond to steroids and at least two other immunosuppressants. As our understanding of these diseases evolves, newer agents that show promise for refractory cases are being employed.

It is the goal of this review to discuss novel agents described and new applications of more established treatment over the last 3 年. A Medline search was employed of all relevant articles published from 2009 到 2011 which included case reports, 临床试验, experimental data, expert opinion, and reviews. Search terms included ‘novel treatment’, ‘therapy’, ‘idiopathic inflammatory myopathies’, ‘myositis’, ‘dermatomyositis’, ‘polymyositis’, ‘inclusion body myositis’, ‘rituximab’, ‘IVIG’, ‘TNF’, ‘myostatin’, ‘follistatin’, and ’gene therapy’. Only those in English were included. Retrieved articles were critically analyzed and references were cross-checked to provide a comprehensive and up-to-date review of the topic. Studies that predate this specified time interval are beyond the scope of this review.

Intravenous immunoglobulin
IVIG exerts diverse effects on the immune system at multiple levels which have allowed for its use in immune-mediated disease including the inflammatory myopathies [Quick and Tandan, 2011; Hartung et al. 2009]. It has been used off-label for a number of years as salvage therapy in refractory PM/DM [Donofrio et al. 2009; Katz et al. 2011]. More recently, a newer case series describes a particular benefit in myositis complicated by steroid-resistant esophageal involvement [Marie et al. 2010]. The favorable outcomes seen suggest that steroids in combination with high-dose IVIG be considered first-line treatment of life-threatening esophageal involvement. In severe interstitial lung disease (ILD)-associated PM, a case report [Bakewell and Raghu, 2011] showed an improvement following three doses of monthly IVIG in a patient with early disease. There was a complete resolution of fibrotic changes on high-resolution computed tomography with sustained remission after 2 years of follow up with no other immunosuppressants used. The authors suggest that IVIG be considered as first-line treatment especially when there is significant pulmonary involvement. This was further supported by a response to this report [Diot et al. 2011] in which a similar ILD-PM case was described, this time unresponsive not only to initial steroids but also to cyclophosphamide. Following infusions of IVIG, this patient also had a dramatic improvement in lung function. Still yet another area where the use of IVIG may be explored is in pregnancy-associated DM. In concurrence with two previous case reports of successful use of IVIG in pregnant patients with DM, Linardaki and colleagues described a patient treated with combined steroids and IVIG during pregnancy with symptom resolution and no adverse effects [Linardaki et al. 2009]. The last dose of monthly IVIG was given 15 days after delivery. Both mother and infant remain disease free after 6 years of follow up, with the mother on no further medications for DM.

An interesting report [Recher et al. 2010] highlights the unexpected beneficial effect of low-dose IVIG in a patient with IBM. Taken together with a similar earlier case report, this may be a strategy that can be explored in IBM, given the prohibitive costs associated with high-dose treatment that often fails to produce results in this subgroup of patients. Nevertheless, in our personal experience, IVIG has failed to be of benefit in our IBM patients. In juvenile dermatomyositis (JDM), a retrospective study identified 8 patients who were able to avoid steroid treatment with the use of IVIG +/- additional immunosuppressants including methotrexate [Levy et al. 2010]. 这将产生重要影响，特别是对于儿童群体，长期接触类固醇会产生严重后果.

静脉输注是免疫球蛋白最常见的给药途径 (免疫球蛋白) 在自身免疫性疾病中. 最近, 一项研究 [丹尼尔等人. 2011] 报道了皮下注射 IVIG 在 7 活动性难治性 PM 或 DM 患者. 皮下注射免疫球蛋白 (脊髓损伤免疫球蛋白) 经过一段时间的培训后，在家中通过可编程泵进行管理. IVIG 每月剂量 2 g/kg 分成等剂量，每周一次皮下注射. 所有患者均表现出良好的治疗反应，作者认为这支持皮下注射 Ig 途径. SCIg 的优点包括无需静脉通路, 日复一日更稳定的血清 IgG 水平, better resistance against infections, home-based self-administration requiring minimal skills, rapid infusions at a speed of 20–30 ml/h, and decreased risk for fluid overload or hyperosmolarity [Rezaei et al. 2011]. This may be a practical and economic alternative that is worth further exploration.

Rituximab
Rituximab is a chimeric, murine/human monoclonal antibody directed against the CD20 antigen found on the surface of B lymphocytes which has found application in a variety of autoimmune conditions including rheumatoid arthritis (RA) and systemic lupus erythematosus. The premise for use in IIMs has included the presence of disease-specific antibodies, immune complex deposition and presence of B cells in inflammatory infiltrates of involved muscles [Majmudar et al. 2009].

There have been several case reports describing the successful use of rituximab in DM and PM mainly in cases refractory to conventional therapy including IVIG [Majmudar et al. 2009; Mahler et al. 2011]. It seems there is a favorable trend in patients with myositis-specific antibodies including anti-Jo1, which appears in keeping with the mechanism of action of the drug [Frikha et al. 2009]. There is particular note of successful use with skin-predominant DM [Joshi et al. 2011], and in ILD in the antisynthetase syndrome [Sem et al. 2009]. In one case report [Vandenbroucke et al. 2009], ILD which was the remaining unresponsive aspect of the disease responded favorably to rituximab initiation. In IIM associated with signal recognition particle (SRP), a case report [Whelan and Isenberg, 2009] showed no benefit, but a larger case series [Valiyil et al. 2010] showed good response with improvement in manual muscle strength and/or decline in creatine kinase (CK) levels in six out of eight patients treated with rituximab. In immunosuppressive naïve dermatomyositis, one case showed sustained remission after only one course of rituximab (1000 mg on days 0 和 14) [Haroon and Devlin, 2010].

In the Auto-Immunity and Rituximab (AIR) registry in France, patients with refractory IIM (unresponsive to at least one immunosuppressant) were analyzed for patient characteristics, rituximab indication, regimen and tolerance [Couderc et al. 2011]. Thirty patients with PM, DM, and the antisynthetase syndrome were included. Rituximab was found to be effective in over 50% of patients on the basis of CPK levels, steroid dose, and physician opinion. Although there was an absence of standardized treatment and control group, with a small population size and short follow up, there was a trend to benefit. This lends further support to previous case reports of successful use of rituximab in IIMs.

The largest randomized controlled trial to date with regards to the use of rituximab in myositis (RIM trial) was presented as an abstract at the American College of Rheumatology meeting [Oddis et al. 2010]. As of the writing of this review, the trial has not yet been published in full manuscript form. This large NIH-funded trial included 200 DM/PM adult and pediatric patients who were refractory to both steroids and an additional immunosuppressant. Both groups were given two doses of rituximab (1 g 1 week apart). One group received the drug first and placebo 8 weeks later while the second group received placebo first followed 8 weeks later by rituximab. It was the ‘time to beginning active rituximab’ which was randomized with a primary endpoint of time to achieve improvement between the two groups. Owing to the inclusion of pediatric patients, a short 8-week run-in phase for the placebo group was required. This may have been too short to allow a distinction between the treatment and placebo curves to be seen. Although both the primary and secondary endpoints were not met as there was no significant difference between both groups, 83% of patients met the IMACS definition of improvement in the trial. It is our conclusion that this may be taken as additional support for the use of rituximab in myositis and suggests the possibility of a flaw in study design rather than actual treatment failure.

利妥昔单抗是应用最广泛的 B 细胞导向疗法. 抗体的嵌合性质可能是与药物相关的一些输注反应的原因. 人源化抗 CD20 分子，包括 ocrelizumab, 奥法木单抗, 和 veltuzumab 正在开发中，可能会被证明具有更好的副作用 [莱韦斯克, 2009]. 多种 B 细胞导向药物也在开发中，包括靶向 CD22 的药物, CD19, CD40-CD40L, B细胞激活因子 (巴夫), 和增殖诱导配体 (四月). 尽管测试这些药物并在多种疾病中找到应用令人兴奋, 关于它们在临床实践中的最佳用途以及 B 细胞在疾病发病机制中的作用，仍然存在许多问题. 它们是否会取代利妥昔单抗的使用仍有待观察.

生物制剂
TNF inhibitors
TNFα offers a potential therapeutic target as it has been proposed to play a role in the pathogenesis of inflammatory myopathies although somewhat ill-defined. Small uncontrolled series using various TNF inhibitors have shown mixed results [Stubgen, 2011]. As such, they have not been considered to represent consistently valuable options for either drug-naïve or refractory IIMs. A recent well-designed randomized placebo-controlled trial of etanercept in dermatomyositis was conducted [Muscle Study Group, 2011]. Eleven subjects, including one from our institution, were randomized to receive etanercept 50 mg SC weekly for 52 weeks and 5 to placebo with a standardized (‘forced’) tapering of steroids as tolerated during the first 24 weeks of the study. Principal outcomes were adverse events, time from randomization to treatment failure (无法戒掉泼尼松), 和平均泼尼松剂量 24 周. 所有服用安慰剂的患者均治疗失败，而 5 在......之外 11 依那西普组成功戒掉泼尼松. 注意到类固醇节约效应. 中位平均泼尼松剂量 24 依那西普组的周数为 1.2 毫克/天与 29.2 安慰剂组毫克/天. 这项研究的优势在于其试验设计. 类固醇逐渐减量成功的证明具有重要的临床意义. 这项研究的局限性在于，其最初严格的纳入标准包括未接受过治疗的患者或仅服用泼尼松少于 2 几个月的时间无法进行足够的招募，并且需要随后放宽纳入标准以包括那些患有更难治性疾病的人. 总共, 仅有的 16 的 40 计划的患者能够入组. Nevertheless, 这些令人鼓舞的发现表明，对依那西普的进一步研究, 和其他TNF- 抑制剂, 在肌炎中需要.

阿巴西普
阿巴西普是一种选择性共刺激抑制剂，可抑制效应 T 细胞上表达的 CD28 的结合，从而减少 T 细胞激活. 一名传统治疗难治的多发性肌炎患者后来尝试使用阿巴西普，取得了良好的临床反应 [穆苏鲁阿纳和卡瓦拉斯卡, 2011].

阿仑单抗
阿仑单抗是一种针对淋巴细胞上 CD52 的人源化单克隆抗体. 进行了原理验证研究，以检查 IBM 中的阿仑单抗是否会消耗外周血淋巴细胞, 肌内膜 T 细胞并改变一组疾病的自然病程 13 患者 [达拉卡斯等人. 2009]. Results of this small and uncontrolled study were promising in that one series of infusions was able to slow down progression of disease (as compared with natural history) up to 6 月, produced improvement in strength in some patients and reduced inflammation.

Tocilizumab
Interleukin 6 (IL-6) appears critically involved in the development of polymyositis and its blockade warrants further investigation for the treatment of refractory cases [Okiyama et al. 2009]. Two patients with PM refractory to multiple immunosuppressants were started on a trial of tocilizumab, a humanized anti-IL-6 receptor antibody [Narazaki et al. 2011]. There was a normalization of CK levels during treatment. No information regarding follow up and muscle strength was provided, 然而.

Anakinra
An increased expression of IL-1 in muscle tissue has been seen in patients with inflammatory myopathies, and treatment with an IL-1 receptor antagonist may be an emerging strategy. A small open-label pilot study with anakinra, 100 mg subcutaneously per day, was undertaken in 15 患者 (下午, DM, and IBM) with treatment-resistant disease [Dorph et al. 2009]. Improvement as defined by the IMACS criteria was seen in seven patients (three with PM, three with DM, and one with IBM). A follow-up study was done probing the biological explanation for improvement in responders focusing on effector T-cell function [Zong et al. 2011]. The authors’ findings indicate that anakinra might favor T-cell differentiation into Th1 rather than Th17 as indicated by more interferon gamma (IFNγ) and less IL-17A secretion.

MEDI-545
类型 1 IFN has gained focus in the treatment of IIMs with the finding that there is marked overproduction of type 1 IFN-inducible transcripts and proteins in DM muscle with a similar phenomenon seen in blood [Greenberg, 2010A, 2010乙; Lundberg and Helmers, 2010]. It is unknown what drives the sustained presence of type 1 IFN inducible molecules in myositis, but evidence that these molecules injure myofibers seems especially strong. Therapeutic development of IFNα blockade has been explored in a phase 1b trial of MEDI-545 (anti-IFNα antibody) in DM and PM [ClinicalTrials.gov identifier: NCT00004451]. The data has not yet been released.

Future potential biologic agents
Understanding the pivotal mediators of inflammatory muscle disease at a molecular level will lead to even more targets for therapy. A study [Szodoray et al. 2010] 试图描述广泛的 T- 和 B 细胞细胞因子, 生长因子, IIM 患者中的趋化因子和趋化因子认识到不同亚型之间存在特征差异，这可以反映其不同的病理生理途径. 与健康对照相比，一组复杂的免疫和炎症调节细胞因子被发现显着上调, 还区分 IIM 子集. 这可能导致未来用作疾病的生物标志物, 以及潜在新治疗靶点的开放途径. CXCL10, Th1趋化因子, 也被发现是一个可行的药理学靶点 [克雷肖利等人. 2011].

干细胞移植
自体干细胞移植
严重难治性肌炎病例, 自体干细胞移植 (自体干细胞移植) 可能是一个考虑因素. 在报道的一例中 [Henes et al. 2009], a patient with anti-SRP myositis treated unsuccessfully with multiple immunosuppressants including IVIG, high-dose cyclophosphamide, alemtuzumab and Infliximab, was successfully treated with myeloablative conditioning with cyclophosphamide. Following cyclophosphamide and total body irradiation with reinfusion of CD34+ autologous stem cells and granulocyte colony stimulating factor, a normalization of CK levels, increase in muscle strength, and absence of myositis on MRI was seen. This response was durable after 3 years of follow up. A case report of two patients with severe progressive JDM similarly showed dramatic improvements and sustained remission with ASCT [Holzer et al. 2010]. ASCT was performed using a CD3/CD19 depleted graft after immunoablative conditioning with fludarabine, cyclophosphamide, and antithymocyte globulin, 作者得出的结论是，这是一种低毒性的治疗选择, 难治性疾病.

间充质干细胞移植
间充质干细胞可以抑制多种免疫细胞的活性，免疫原性非常有限. 使用同种异体间充质干细胞移植的开放标签试点研究 (多层螺旋CT) 进行于 10 耐药 DM/PM 患者 [王等. 2011]. 对于大多数患者来说, 血清 CK 下降，同时临床有意义的改善和药物摄入量逐渐减少. 然而, 跟进约 1 年, 没有患者完全停止免疫抑制治疗. 这表明 MSCT 无法治愈, 但对于疾病控制不佳的患者可能是一种有用的辅助手段. 还应该指出的是，有两名患者在 MSCT 后直接因感染后疾病复发而死亡.

基因治疗
如果对当前治疗反应不佳，例如 IBM, 随着分子疗法的使用，出现了一种有希望的治疗途径. 尽管纠正潜在的缺陷是理想的，正如在肢带型肌营养不良症中所尝试的那样 [孟德尔等人. 2009, 2010], 对于遗传基础尚不清楚的特发性炎症性肌病，增加肌肉大小和力量的方法可能是合适的.

卵泡抑素
肌生长抑制素是一种转化生长因子 β 家族成员，在成人和发育中的骨骼肌中表达，是肌肉生长的负调节因子 [海德特等人. 2010]. 通过抑制肌肉生长抑制素途径来增加肌肉大小和力量的策略令人鼓舞 [根据 Rodino-Klapac 等人的说法. 2009]. 发展最深入的是卵泡抑素的利用, 它已成为肌肉生长抑制素的有效拮抗剂，能够阻碍骨骼肌上的信号传导受体. 它最初是在猪卵巢卵泡液中分离出来的，可减弱促卵泡激素的释放. 除了在生殖生理学中的作用外，卵泡抑素还具有多种功能，这引起了人们对其用于肌肉疾病的靶向方法的关注. A gene therapy approach to myostatin inhibition through follistatin has been explored as it offers the potential for a single administration of vector carrying the follistatin gene with persistent expression for many years, perhaps even for the lifetime of the individual. Preliminary studies using alternatively spliced cDNA of follistatin delivered by adeno-associated virus demonstrated increased muscle size and strength with reduced fibrosis in dystrophic mice [海德特等人. 2008]. Preclinical studies performed on healthy monkeys showed similar results and was shown to be safe and effective [Kota et al. 2009]. Given this, using gene therapy with follistatin for inhibition of myostatin is well-positioned for use in the inflammatory myopathies. 目前正在俄亥俄州国家儿童医院对 9 名 IBM 患者进行卵泡抑素基因治疗试验 (肌炎协会, 个人通讯, 2011).

核受体辅阻遏物 1
转录共调节因子控制许多转录因子的活性，并对基因表达产生广泛的影响. 一项研究表明，肌肉特异性核受体辅阻遏物的缺失 1 (NCoR1) 由于肌肉质量以及线粒体数量和活性增加，小鼠的基因导致运动耐力增强 [山本等人。. 2011]. 虽然这个数据是初步的, 干扰 NCoR1 等辅助抑制因子可能会被用作改善肌肉质量和功能的策略.

RNA干扰
RNA干扰 (RNAi) 是细胞用来降低特定基因活性的自然过程. In conjunction with this, MiRNAs, or microRNAs, are endogenous triggers of RNAi which have been shown to have essential roles in developmental processes including in skeletal muscle [Sibley and Wood, 2011; Mishra and Bertino, 2009]. A key feature of the RNAi and miRNA mechanism is sequence specificity. A differential expression of MiRNAs has been described in several pathological processes including PM, DM, and IBM [Sibley and Wood, 2011]. Although the exact significance of this is unclear, therapies manipulating miRNA activity may be a particularly powerful strategy for targeting dysregulated disease pathways in the future.

Other agents
Retinoids
One study [Ohyanagi et al. 2009] examined the effect of retinoids on experimental autoimmune myositis. Retinoids have important roles in cell proliferation, differentiation, and morphogenesis with modulating function on inflammatory and immunocompetent cells including T cells and macrophages. Following induction of autoimmune myositis in mice, administration of AM80 (a synthetic retinoid launched in the Japanese market for promyelocytic leukemia) showed attenuated inflammatory changes both prophylactically and therapeutically. There was also an attenuated production of serum antimyosin antibodies found. This finding was thought to be due to regulation of Th differentiation, reduction of antimyosin antibody production, and decreased chemokine expression.

Calpeptin
It has been hypothesized that calpain (a Ca2+-sensitive protease) activation bridges between extracellular inflammatory stress and intracellular secondary inflammatory changes seen in muscle cells in IIMs. With the addition of calpeptin, a calpain inhibitor, 细胞外炎症刺激后对大鼠成肌细胞的影响, 细胞凋亡减弱，MHC-1 和炎症相关转录因子的表达减弱 [野崎等人. 2011]. 作者提出钙蛋白酶可能是治疗炎症性肌病的潜在治疗靶点.

咪唑立宾
Mizoribine 是一种嘌呤抗代谢药，可抑制 T 细胞活化和增殖以及 B 细胞增殖. 日本批准用于抑制肾移植后的排斥反应, 狼疮性肾炎, 和RA. 米佐立宾作为类固醇节约剂成功用于患有 CVA 的 PM 患者, 据报道使用类固醇后出现 DM 和 MI [诹访等. 2009].

他汀类药物
他汀类药物具有多效作用，包括抑制炎症、免疫调节和抗氧化作用. A pilot study explored the use of simvastatin 40 mg in IBM [Sancricca et al. 2011]. In an open-label trial in 14 patients over 12 月, none of the patients showed significant clinical improvement. Given the already known toxic effects in muscle, simvastatin cannot be recommended for the treatment of sporadic inclusion body myositis at this time.

Exercise training
More recently, physical exercise in combination with immunosuppressive treatment has been found to have beneficial effects on clinical outcomes in patients with myositis [Nader and Lundberg, 2009]. Data is also suggestive that exercise exerts anti-inflammatory effects both systemically as well as locally in muscle. A new nonpharmacological approach has been proposed for IBM patients involving vascular occlusion in association with resistance training [Gualano et al. 2010A, 2010乙]. Investigators demonstrated that by restricting muscle blood flow using tourniquet cuffs in conjunction with moderate intensity resistance training, a gain in muscle mass and function was seen after a 12-week training program. A video component of the article can be found at http://www.jove.com/details.php?id=1894.

Conclusion
In summary, the treatment of inflammatory myopathies to date has been complicated by the rarity of the disease and the paucity of large randomized clinical trials. With the introduction and use of the IMACS standardized response criteria (definition of improvement) in clinical trials, conduction of trials and comparison between them will be easier. Although challenges remain as to the treatment of refractory cases, continued elucidation of the pathogenesis, understanding of the different phenotypes, 抗体状态, 细胞因子环境, 甚至调控基因也为治疗靶点开辟了许多途径. 我们预计这些努力最终将为肌炎患者带来更好的临床结果.

资金