重症肌无力的AChR自身耐受研究进展

重症肌无力（myasthenia gravis,MG）是抗乙酰胆碱受体（acetycholine receptor,AChR）抗体介导、细胞免疫依赖性、补体参与的神经－肌肉接头处的自身免疫性疾病,是神经肌肉接头处最常见的疾病,其发生的关键在于机体针对AChR所产生的免疫应答异常。     

烟碱样胆碱能受体（N-AChR）的分离提纯以及在药理毒理研究中的应用

本报告了从丁氏双鳍电鳐电器官中分离纯化N—AChR，研究其生化性质，并在毒物、药物、实验性重症肌无力（EAMG）等方面进行了研究。一、N—AChR的分离提纯：N—AChR膜片可用于研究天然状态下受体性质和功能。我们用几次蔗糖密度连续梯度和不连续梯度离心分离，得到的受体膜片无活性胆碱酯酶，比活性达5nmol α-神经毒素结合点／mg蛋白。采用眼镜蛇α-神经毒素为配基制成的亲和层析柱，提纯了N—AChR蛋白，达到了等电聚焦纯，等电点为5．2。发现PAGE出现两条带，     

重症肌无力患者血清乙酰胆碱受体抗体分类及自身抗体的检测方法

重症肌无力抗体用于诊断的价值决定于对该抗体检测方法的敏感性和特异性。这方面多年来已有不断发展和改进。笔者主要阐述了乙酰胆碱受体、抗体的分类及自身抗体的检测方法。     

胸腺瘤切除治疗重症肌无力的护理

重症肌无力是一种影响神经肌肉接头传递的自身免疫性疾病，发病机理不明确，近年来研究发现，重症肌无力主要是突触后膜乙酰胆硷受体（AChR）发生的病变所致。而胸腺是AchR抗体产生的主要场所，因此，本病的发生一般与胸腺有密切的关系。重症肌无力的治疗有胸腺切除、药物治疗、血液疗法。胸腺切除术治疗重症肌无力的成功除了外科医生的手术外，更重要的有赖于手术前后的专业护理，其重点是术前对重症肌无力的评估及术后各种危象的早期观察、预防和护理。     

他克莫司治疗重症肌无力临床研究进展

重症肌无力是乙酰胆碱受体抗体（Ach RAb）介导的、细胞免疫依赖及补体参与的神经-肌肉接头处传递障碍的自身免疫性疾病.其诊断主要根据特征性的病态疲劳性、新斯的明试验、抗体检测及重复神经刺激（repetitive nerve stimulation,RNS）检查[1].T细胞依赖机制在重症肌无力的发病过程中占重要地位.重症肌无力治疗以手术和肾上腺糖皮质激素为基本的治疗措施,传统免疫抑制剂也常被用于辅助治疗.部分重症肌无力患者不能耐受传统的免疫治疗（包括糖皮质激素、硫唑嘌呤、环磷酰胺、环孢素和吗替麦考酚酯等）或应用无效.他克莫司作为第二代免疫抑制剂逐步被应用于重症肌无力的治疗,并希望在治疗重症肌无力中能够取得良好的发展前景.本研究就他克莫司在重症肌无力治疗中的作用机制、疗效及不良反应进行综述.     

重症肌无力患者血清抗乙酰胆碱受体抗体和抗突触前膜抗体测定及其意义

我院于1988年7月～1990年6月间采用酶联免疫吸附法,对38例重症肌无力(MG)患者行血清抗乙酰胆碱受体抗体(AchRAb)及抗突触前膜抗体(下称抗前膜抗体)测定。现将检测结果分析报告如下。对象与方法一、对象 MG组:选取在我院门诊和住院诊治的MG患者38例,所有病例均根据典型的临床表现、新斯的明试验或肌电图检查证实。其中眼肌型25例,延髓肌型4例,脊髓肌型2例,全身肌无力型7例。本组男性23例,女性15例;年龄4～63岁,平均30.8岁,其中<30岁和>30岁各19例;病程8天～20年,平均2年8个月。伴发胸腺瘤者5例(眼肌型3例、全身     

小儿重症肌无力危象

目的 研究小儿重症肌无力危象的临床特点、诊断标准及治疗方法。方法 对4例重症肌无力危象患儿作一回顾性分析。结果 4例为急性起病,分别表现为两侧眼睑下垂,眼球活动受限,吞咽困难、四肢肌力、肌张力减弱。结论 小儿重症肌无力的病史和新斯的明试验阳性是诊断本病的重要依据。使用溴化吡啶斯的明和泼尼松可防止危象再发生。     

胸腺切除术后应用免疫抑制剂治疗重症肌无力的分析研究

目的探讨重症肌无力患者胸腺切除术后应用免疫抑制剂治疗的CD4＋CD25＋Tr细胞百分率和乙酰胆碱受体抗体的变化。方法 A组（n=34）重症肌无力患者胸腺切除术后应用免疫抑制剂组;B组（n=35）重症肌无力患者胸腺切除后未应用免疫抑制剂组;用流式细胞仪计数外周血A、B2组治疗前和治疗后6个月的CD4＋CD25＋Tr细胞的百分率和酶联免疫吸附法检测乙酰胆碱受体抗体（AchR-Ab）,应用许氏临床评分法对病情的严重程度和转归进行评定。结果 A、B2组比较CD4＋CD25＋Tr细胞百分率、乙酰胆碱受体抗体（AchR-Ab）、临床相对计分在治疗后6个月差异有统计学意义（P〈0.01）。结论 HTK胸腺切除后应用免疫抑制剂6个月后,重症肌无力患者的CD4＋CD2＋5Tr细胞的百分率明显增高和AchR-Ab明显降低,肌无力症状稳定缓解。     

免疫抑制剂治疗15例重症肌无力有效后停用溴吡斯的明的观察

目的：在经免疫抑制剂治疗有效的全身型重症肌无力（MG）患者中停用溴吡斯的明后观察肌无力病情的变化。方法：收集15例对糖皮质激素和（或）硫唑嘌呤治疗有良好疗效且同时服用溴吡斯的明的MG患者,进行《改良的美国重症肌无力基金会QMG量表（MGFA-QMG）》、《徒手肌力量表（MMT）》和《MG日常生活量表（MG-ADL）》评定,随后停用溴吡斯的明、但保留原有免疫抑制剂治疗,1个月后门诊随访评估。结果：与停用溴吡斯的明前相比,1个月后15例MG患者的MGFA-QMG、MMT和MGADL评分均无明显变化（p〉0.05）。结论：对于病情稳定的MG患者并非必须使用溴吡斯的明,停用后不会加重患者的病情。     

泼尼松联合丙种球蛋白对重症肌无力患者外周血 乙酰胆碱受体抗体水平及转化生长因子 -β1 的影响

目的：观察泼尼松联合丙种球蛋白对重症肌无力（MG）患者外周血乙酰胆碱受体抗体（AChR-Ab）水平及转 化生长因子 -β1（TGF-β1）的影响。方法：选择 94 例 MG 患者为观察对象，按随机数表法分为观察组和对照组各 47 例。 对照组给予泼尼松口服，观察组采用泼尼松联合丙种球蛋白治疗，比较治疗前及治疗 1 个月后两组患者外周血 AChRAb、TGF-β1 水平变化，并分析两组患者治疗 1 个月后的疗效及治疗 1 个月内的不良反应情况差异。结果：治疗 1 个月后， 观察组疗效明显高于对照组（P＜0.05）；两组外周血 AChR-Ab 水平均较治疗前明显降低，且观察组明显较同期对照组 低（P＜0.05），两组 TGF-β1 水平均较治疗前明显升高，且观察组明显较对照组高（P＜0.05）。治疗 1 个月内，两组 药物不良反应率比较无明显差异（P＞0.05）。结论：丙种球蛋白联合泼尼松治疗 MG 有效，可显著提高 TGF-β1 水平 并降低外周血 AChR-Ab 水平，且安全性良好，不易发生不良反应。     

A novel immunomodulator, FTY720, prevents development of experimental autoimmune myasthenia gravis in C57BL/6 mice

Prophylactic oral administration of a novel immunomodulator (immunosuppressant), FTY720 (1 mg/kg, three times a week), completely prevented the development of experimental autoimmune myasthenia gravis (EAMG) in C57BL/6 mice. EAMG has been used as an animal model for human myasthenia gravis, and was established by immunizing the mice with acetylcholine receptor (AChR) from Torpedo californica. FTY720 also suppressed the production of both anti-Torpedo californica AChR antibody and anti-mouse AChR autoantibody by the mice, which were observed in mice in which EAMG had become established. These results strongly suggest that FTY720 is a promising candidate for treatment of human myasthenia gravis.     

黑斑双鳍电鳐烟碱受体单克隆抗体及其在重症肌无力病研究中的应用

以纯化的NAChR为抗原免疫Balb/c小鼠,取其脾细胞与骨髓瘤细胞P_3U_1融合生成杂交瘤,用间接免疫荧光法和ABC-ELISA进行筛选,建立了三株NAChR McAb杂交瘤细胞株(A_7,E_4,G_3)。三种McAhs均属IgG_1,E和G_3可与NAChR上的α亚基结合。以E_4和G_3 McAbs为探针,用ELISA检测24例MG病人血清,发现12例病人血脚中存在McAb E_4的抗独特型抗体,其中11例有McAb G_3的抗独特型抗体,提示MC病人体内可能存在共有的独特型和功能性的自身免疫网络。     

Exacerbated muscle dysfunction by procainamide in rats with experimental myasthenia gravis.

The induction of experimental autoimmune myasthenia gravis (EAMG) has long been shown to result in inefficient function of the acetylcholine receptor (AChR) and concomitant impairment of AChR-dependent neuromuscular communication. As an animal model of human myasthenia gravis, AChR-immunized rats demonstrate symptoms of MG very similar to those observed in human patients resulting from the presence of circulating anti-AChR antibodies which interfere with the normal function of the receptor. In addition to antibody antagonists of neuromuscular function, a variety of drugs have been observed to be associated with possible exacerbations of impaired neuromuscular function leading to myasthenic crisis in some MG patients. One drug, the cardiac anti-arrhythmic agent, procainamide, has been reported to cause both pre-synaptic and post-synaptic electrophysiologic effects at the neuromuscular junction. The study described below extends these observations to include the demonstration of perturbed AChR-dependent contractile muscle function in a rat model of MG.     

Biomedical Application of Snake Venom Neurotoxins: Acetylcholine receptor and myasthenia gravis

Abstract

The venom of many of the snakes of the Elapidae and Hydrophiidae is highly toxic, producing flaccid paralysis and respiratory failure in animals. These effects mainly are attributable to postsynaptic neurotoxins known to bind specifically and tightly to the nicotinic acetylcholine receptor (AChR). Sequence analyses findings for postsynaptic neurotoxins from many snake species show they can be classified into short (61-62 amino acid residues) and long (71-74 amino acid residues) neurotoxins. Short-chain neurotoxins bind specifically, but weakly to AChRs, and the binding is slowly reversible. This property makes them particularly useful for the purification of AChRs. Long-chain neurotoxons, such as α-Bungarotoxin (α-BuTx), bind specifically and tightly to AChRs and are useful as probes to measure the number of AChRs in the bound radioiodinated neurotoxin contents. The most common clinical application of neurotoxin is in the detection of nicotinic AChRs and their antibodies in research related to the pathogenesis of myasthenia gravis (MG). We have developed new assay systems for detecting antibodies that recognize different antigenic determinants in AChR protein. Using them, we detected a markedly high prevalence of anti-AChR antibodies in MG. This determination now allows for a definite diagnosis of MG. We also show that the blocking effect of the anti-AChR antibodies in MG sera is due to stenc hindrance caused by their binding to a region other than that for α-BuTx.     

胸腺瘤合并重症肌无力25例外科诊治分析

【摘要】目的探讨胸腺瘤合并重症肌无力的外科诊治经验。方法对本院2001年1月～2011年1月收治的25例胸腺瘤合并重症肌无力患者的临床资料进行分析、总结。结果术后2例患者发生重症肌无力危象．经气管切开,呼吸机辅助呼吸等抢救治疗后痊愈,出院后随访3个月～3年,本组完全缓解13例,改善8例,无效4例,无死亡病例。结论合理选择病例,重视同术期管理,手术切除彻底,可减少重症肌无力危象,外科手术治疗胸腺瘤合并重症肌无力能获得良好的疗效。     

New treatment approaches to myasthenia gravis

Myasthenia gravis is an autoimmune disorder in which neuromuscular transmission is impaired by autoantibodies to the acetylcholine receptor (AChR). There are 3 varieties of generalised myasthenia with differing genetic susceptibilities. There is also a purely ocular form in which the weakness is confined to the extraocular muscles, and a neonatal variety which occurs in 20% of babies born to myasthenic mothers due to transplacental passage of the acetylcholine receptor antibody. Another variety of myasthenia occurs several months after treatment with D-penicillamine. The role of the thymus is suggested by abnormal histology in patients with myasthenia and by the beneficial effects of thymectomy in more than two-thirds of patients. Thymectomy is indicated in most patients unless the symptoms are minimal or the weakness is confined to the extraocular muscles. Most patients require treatment with anticholinesterase drugs to prolong the action of acetylcholine at the muscle end-plate. Overdosage of these drugs can provoke a cholinergic weakness. Remissions can be achieved with corticosteroids in 80% of patients. Immunosuppression with azathioprine is used mainly in patients who do not respond to thymectomy or in those patients who are considered unsuitable for operation. Plasma exchange can cause a rapid but temporary improvement in myasthenia, and has no long term place in its treatment.     

AChR-specific immunosuppressive therapy of myasthenia gravis

Myasthenia gravis (MG) is an organ-specific autoimmune disease characterized by muscle fatigability. In most cases, it is mediated by autoantibodies targeting muscle nicotinic acetylcholine receptors (AChRs) at the neuromuscular junction. Experimental autoimmune myasthenia gravis (EAMG) is an animal model for MG, which is usually induced by immunization with AChR purified from fish electric organ. Pathological autoantibodies to AChRs are directed at the extracellular surface, especially the main immunogenic region (MIR). Current treatments for MG can help many but not all patients. Antigen-specific immunosuppressive therapy for MG that specifically suppresses the autoimmune response without affecting the entire immune system and avoids side effects of general immunosuppression is currently unavailable. Early attempts at antigen-specific immunosuppression for EAMG using AChR extracellular domain sequences that form epitopes for pathological autoantibodies risked provoking autoimmunity rather than suppressing it. We discovered a novel approach to specific immunosuppression of EAMG with a therapeutic vaccine consisting of bacterially-expressed human AChR cytoplasmic domains, which has the potential to specifically suppress MG without danger of causing exacerbation. This approach prevents development of chronic EAMG when initiated immediately after the acute phase of EAMG, and rapidly reverses established chronic EAMG when started during the chronic phase of EAMG. Successfully treated rats exhibited long-term resistance to re-induction of EAMG. In this review we also discuss the current understanding of the mechanisms by which the therapy works. Vaccination with AChR cytoplasmic domains in adjuvant is promising as a safe, antigen-specific, potent, effective, rapidly acting, and long lasting approach to therapy of MG.     

Oculo-bulbar myasthenia gravis induced by cytokine treatment of a patient with metastasized renal cell carcinoma

Objective: The occurrence of autoimmune diseases or deterioration of pre-existing disorders has recently been described after cytokine treatment. The present report gives evidence for acquired myasthenia gravis induced by externally administered interferon-α and interleukin-2 in a patient with metastasized renal cell carcinoma. Electromyographic investigations did not reveal generalised myasthenia gravis. However, a highly elevated titre of antibodies against the human acetylcholine receptor and a significant improvement in clinical symptoms during therapy with anticholinesterase drugs, combined with a decremental response in electronystagmography, indicated an intermittent mainly oculo-bulbar form of myasthenia gravis. Received: 9 October 1995/Accepted in revised form: 15 January 1996     

多西他赛联合顺铂与大量糖皮质激素冲击治疗复发胸腺瘤合并重症肌无力的疗效比较

目的：比较多西他赛联合顺铂与大量糖皮质激素冲击治疗胸腺瘤切除术后胸腺瘤复发合并重症肌无力（MG）患者的临床疗效。方法：选取2013年1月-2015年1月就诊于某院的32例胸腺瘤切除术后胸腺瘤复发合并重症肌无力患者。其中,20例患者接受多西他赛联合顺铂治疗（DP组）,12例患者采用大量糖皮质激素冲击治疗。对比观察2组患者治疗前后乙酰胆碱受体抗体（acetylcholine receptor antibody,AchR-Ab）和临床绝对评分（clinic definitely score,CDS）的变化,并记录化疗不良反应的发生。结果： 2组患者的AchR-Ab水平及CDS分别与治疗前相比,治疗后均显著改善,差异有统计学意义（P<0.05）。大量激素冲击组治疗肌无力有效率为97.7%,DP组治疗肌无力有效率为95.0%,2组患者MG治疗的疗效差异无统计学意义（P>0.05）。大量激素冲击组治疗胸腺瘤显效率为75.0%,DP组治疗胸腺瘤显效率为30.0%。2组方案胸腺瘤治疗的疗效差异有统计学差异（P<0.05）。大量激素冲击组患者不良反应的发生率为66.7%,而DP组为25.0%。结论：大量糖皮质激素冲击对复发胸腺瘤合并MG的肌无力和胸腺瘤两方面疗效显著,但不良反应大。多西他赛联合顺铂对复发胸腺瘤合并MG的肌无力疗效显著,同时不良反应小,但对胸腺瘤方面作用不明显。     

Myasthenia gravis. Pathogenesis and current concepts in management

Myasthenia gravis is a disorder of autoimmunity in which neuromuscular transmission is impaired by autoantibodies to the acetylcholine receptor (AChR). There is evidence for more than one form of the disorder with differing genetic susceptibilities. The aetiology is unknown, but thymic involvement is suggested by abnormal histology and by the beneficial response of the disorder to thymectomy in more than two-thirds of patients. Thymectomy is indicated in most patients unless the symptoms are minimal or are confined to the extraocular muscles alone, or the patient is elderly. Thymectomy alone results in remission in about one-third of patients, but, in addition, most patients require symptomatic anticholinesterase drugs to prolong the action of acetylcholine at the muscle end-plate. Over-dosage of these drugs can also cause weakness. Immunosuppression with corticosteroids or azathioprine may also improve myasthenia; at present, these drugs are used mainly in patients who do not respond to thymectomy or in those patients considered unsuitable for operation. Plasma exchange can cause a rapid, though temporary, involvement in myasthenia, but it probably has no long term place in its treatment. Future therapy will probably involve specific immunotherapy, such as anti-idiotype antibodies.