血清阴性和阳性重症肌无力被动转移动物模型的对比观察

目的:通过对血清阴性重症肌无力(SNMG)和血清阳性重症肌无力(SPMG)被动转移动物模型的对比观察,探讨SNMG和SPMG发病机理的异同。方法:分别采用SNMG和SPMG患者血清制作重症肌无力被动转移小鼠模型,观察其临床表现及电生理改变。结果:SNMG和SPMG患者血清均可诱导C57BL/6小鼠出现肌无力症状,其成功率分别为90％、85％;但SNMG组小鼠肌无力症状较SPMG组明显为轻(症状级别均值分别为1.55、2.15,P<.05),电刺激衰减率(40％)和平均衰减幅度(14％)均较后者(分别为75％、21％)为低(P<0.05)。结论:SNMG和SP-MG均是自身抗体介导的自身免疫病,SNMG血清中亦存在致病因子。     

CD40配体在血清AChRab阳性和阴性重症肌无力发病机制中作用的探讨

目的 :研究CD40配体在血清阳性重症肌无力 (SPMG)和血清阴性重症肌无力 (SNMG)主要致病因素产生中的作用。结果 :无论SPMG或SNMG ,外周血单个核细胞体外培养后上清液中γ干扰素 (IFN γ)、白细胞介素 4(IL 4)、抗乙酰胆碱受体抗体 (AChRab)和抗突触前膜受体抗体 (Prsmab)均比健康对照组非常显著增高 (P =0 0 0 0 )。抗CD40L单克隆抗体 (anti CD40Lmonoclonalantibody ,CD40LMcAb)干预后 ,SPMG组与健康对照组的差异无统计学意义 (P >0 0 5 ) ,SNMG组只有PsmRab与健康对照组的差异无统计学意义 (P >0 0 5 ) ,而IFN γ、IL 4和AChRab的水平虽有所下降 ,但仍显著高于健康对照组 (P <0 0 5 )。结论 :SNMG的AChRab、IFN γ和IL 4可能还通过其他途径产生 ,存在其他发病机制。     

苏木醇提物治疗小鼠实验性重症肌无力的研究

目的观察苏木对重症肌无力的治疗效果。方法采用乙酰胆碱受体(AChR)加等量福氏佐剂多次免疫小鼠，复制实验性自身免疫性重症肌无力(EAMG)小鼠模型，将EAMG小鼠随机分为EAMG治疗组及EAMG对照组，治疗组胃内注入苏木醇提物，对照组给予等量生理盐水，治疗4周，观察治疗前后小鼠体重、游泳时间和临床评分变化。结果治疗前治疗组及EAMG对照组小鼠较佐剂对照组及正常对照组小鼠体重减轻、游泳时间缩短、临床评分增高，其差异具有显著性，但EAMG治疗组与EAMG对照组之间比较无显著性差异；治疗后EAMG治疗组症状明显改善，小鼠体重增加、游泳时间延长、临床评分降低，与EAMG对照组比较有显著性差异。结论苏木能明显缓解EAMG小鼠的肌无力症状，促进其功能恢复，是治疗重症肌无力的有效药物。     

肌肉特异性酪氨酸激酶在重症肌无力中的作用(综述)

约有20％重症肌无力(MG)患者血清中检测不到乙酰胆碱受体抗体(AChRAb)，称之为“血清反应阴性MG”(seronegative MG，SNMG)。有报道71％的SNMG患者血清中存在肌肉特异性酪氨酸激酶(MUSK)抗体(MuSKAb)，MuSKAb阳性SNMG患者的流行病学特征、If缶床特点和治疗效果与由AChRAb介导的MG(seropositive MG，SPMG)有所不同，存在较大争议。     

β-银环蛇毒素结合蛋白抗体和乙酰胆碱受体抗体亲和性及其在重症肌无力致病中的意义

为了研究β-银环蛇毒素(β-BuTx )结合蛋白在重症肌无力(MG)致病中的作用和意义。我们用牛膈肌乙酰胆碱受体(AChR)和β-BuTx结合蛋白分别免疫Lewis鼠。结果显示AChR免疫鼠能诱导典型的实验性重症肌无力(EAMG)临床症状和血清中高效价的抗AChR抗体。β-BuTx结合蛋白免疫鼠组血清中虽然也能检测到较高效价的β-BuTx结合蛋白抗体,但未观察到明确的EAMG症状。分析和比较了两组免疫鼠血清抗体的亲和指数后发现,β-BuTx结合蛋白抗体亲和指数明显低于AChR抗体亲和指数。我们认为:β-BuTx结合蛋白在实验动物中具有抗原性,但它的抗体亲和性远较AChR为低,这可能是β-BuTx结合蛋白缺乏致Lewis鼠肌无力的重要因素之一。     

重症肌无力患者酪氨酸激酶抗体的检测

目的探讨酪氨酸激酶抗体（MuSKAb）在血清阴性重症肌无力（SNMG）发病中的作用。方法采用放射免疫法检测198例重症肌无力（MG）患者血清中抗乙酰胆碱受体抗体（AChRAb）水平，筛选出SNMG血清样本再行MuSKAb水平检测。结果MG患者血清AChRAb浓度明显高于对照组（P〈0．05），其阳性率为81．3％，SNMG患者血清MuSKAb均为阴性。结论MuSKAb可能在中国SNMG患者中的检出率较低。     

重症肌无力发病机制的研究进展

重症肌无力 (myastheniagravis,MG)是一种神经肌肉接头 (neuromuscularjunction,NMJ)传递功能障碍的自身免疫性疾病,其发病机制尚未完全阐明。传统观点认为MG的发病与乙酰胆碱受体自身抗体(AChR Ab)介导的体液免疫密切相关,但最近发现NMJ处其他抗体、抗原特异性T细胞、细胞因子、调节性T细胞、遗传因素等在MG的发病中也扮演了重要的角色。一、体液免疫临床上发现大约 80%的MG患者血清中能检测到AChR Ab,称为血清阳性重症肌无力 (seropositivemyastheniagravis,SPMG),而另外 20%的MG患者体内不能检测到AChR Ab,即所谓血清…     

重症肌无力模型发病机制及体内酶的表达

重症肌无力(MG)是由抗体介导、T细胞依赖与补体(C)参与的自身免疫性疾病.实验性自身免疫性重症肌无力(EAMG)的动物模型与MG患者在临床症状、电生理、生化水平、超微结构形态学、免疫学、生物效应及药效等方面颇为相似.该文对EAMG发病机制的研究历史及现状进行综述,侧重介绍EAMG体内酶和蛋白的表达水平.     

乙酰胆碱受体α亚基125-147肽段制作实验性重症肌无力动物模型的研究

目的研究用乙酰胆碱受体α亚基125-147(Tα125-147)肽段制作实验性重症肌无力(EAMG)的动物模型。方法给实验组Lewis鼠(12只)皮下注射人工合成电鳗乙酰胆碱受体Tα125-147肽段,观察接种后鼠的肌力变化,应用低频重复电刺激检测电衰减反应及酶联免疫法检测血清乙酰胆碱受体抗体(AChR-Ab)滴度;并与对照组鼠(8只)比较。结果在第2次接种后1周实验组6只鼠逐渐出现肌无力症状,11只鼠低频重复电刺激电衰减反应( )及血清AChR-Ab( );对照组鼠均无肌无力症状,低频重复电刺激电衰减反应(-),血清AChR-Ab7只鼠(-),1只(±),两组比较差异有显著性(均P<0.01)。结论用人工合成乙酰胆碱受体Tα125-147肽段免疫Lewis鼠可以成功制作EAMG动物模型。     

重症肌无力动物模型的建立

实验性自身免疫性重症肌无力(EAMG)动物模型与重症肌无力(MG)患者在临床症状、电生理、生物化学、超微结构形态学、免疫学、生物效应及药效上颇为相似。研究EAMG动物的发病机制对MG发病机制的探索具有十分重要的意义。此文就EAMG的各种诱导方法及评定标准进行综述。     

Acetylcholine receptor antibodies in myasthenia gravis are associated with greater risk of diabetes and thyroid disease

OBJECTIVE: Myasthenia gravis (MG) may be associated with the presence of acetylcholine receptor antibodies (AChRAb) [seropositive MG (SPMG)] or their absence [seronegative MG (SNMG)]. Along with features of MG, the presence of the AChRAb may relate to the existence of other immune-mediated diseases. We sought to determine the association of SPMG with other potential autoimmune diseases. METHODS: A retrospective evaluation of prospectively identified MG patients at a tertiary care center was performed, with patients separated into SPMG and SNMG. Prevalence of other immune-mediated disorders, as well as the epidemiology, sensitivity of diagnostic testing, and thymic pathology, was contrasted between both patient groups. RESULTS: Of the 109 MG patients identified, 66% were SPMG. SPMG was associated with a greater likelihood of significant repetitive stimulation decrement, the presence of either thymoma or thymic hyperplasia, and the presence of thyroid disease. In addition, all patients with a diagnosis of diabetes, concurrent with MG, were found to be SPMG. CONCLUSIONS: AChRAb and SPMG impart not only a distinctive clinical and electrophysiological phenotype of MG, but are also associated with the heightened presence of endocrinological disease.     

The effectiveness of thymectomy on seronegative generalized myasthenia gravis: comparing with seropositive cases

OBJECTIVES: To investigate the efficacy of thymectomy between patients with seronegative myasthenia gravis (SNMG) and seropositive myasthenia gravis (SPMG). METHODS: We present here the first Taiwanese retrospective paired cohort study comparing the effectiveness of thymectomy among 16 seronegative and 32 seropositive MG patients after matching for age-of-onset and time-to-thymectomy, and following up over a mean of 35 +/- 20 (7-86) months. Clinical characteristics and complete stable remission (CSR) rates were compared and analyzed between the groups. RESULTS: There were no major clinical differences between the two groups except for our finding of a lower percentage of SNMG receiving preoperative plasmapheresis or human immunoglobulin than SPMG (31% for SNMG vs 72% for SPMG, P = 0.007). CSR rates calculated using the Kaplan-Meier method were similar in the two groups (38% for SNMG vs 50% for SPMG, P = 0.709). The median time for CSR was 47.4 months for SNMG and 48.2 months for SPMG. Thymic hyperplasia were the most common pathology (69% for SNMG vs 88% for SPMG, P = 0.24). During the follow-up period, we found no group difference on prednisolone or pyridostigmine dosages. Significant postoperative dosage reductions on pyridostigmine, but not on prednisolone, were found in both groups. CONCLUSIONS: Thymectomy has a comparable response among SNMG and SPMG in our study. Thymic hyperplasia is prevalent in our SNMG patients and thymectomy may also be a therapeutic option to increase the probability of remission or improvement in SNMG. More prospective controlled trial will be helpful in the future.     

IgG from "seronegative" myasthenia gravis patients binds to a muscle cell line, TE671, but not to human acetylcholine receptor

Antibodies to acetylcholine receptor (AChR) are found in 85% of patients with myasthenia gravis (seropositive MG [SPMG]) and are thought to be pathogenic; but in 15% of MG patients, the standard immunoprecipitation test for anti-AChR is negative (seronegative MG [SNMG]). Here, we used a novel approach, fluorescence-activated cell sorting analysis, to measure binding of SPMG and SNMG IgG antibodies to rhabdomyosarcoma cell lines that express human adult (TE671-epsilon) or fetal (TE671-gamma) AChR, and to human embryonic kidney (HEK) fibroblasts that express adult human AChR (HEK-AChR). We found that whereas most SPMG antibodies bind to all three cell lines, IgG from 8 of 15 SNMG sera/plasmas bind to the surface of both TE671 cell lines but not to HEK-AChR cells. These results indicate that SNMG antibodies bind to a muscle surface antigen that is not the AChR, which strongly supports previous studies that suggest that SNMG should be considered a distinct subtype of MG.     

乙酰胆碱受体抗体与大鼠中枢神经元烟碱型乙酰胆碱受体之间免疫结合反应

本研究旨在探讨长期以来无定论的重症肌无力（MG）患者血和脑脊液（CSF）中的乙酰胆碱受体抗体（AChRab）能否与中枢神经元烟碱型乙酰胆碱受体（神经-nAChR）结合，并引起中枢神经系统（CNS）功能障碍。用免疫亲和层析法从AChRab阳性的全身型MG患者血中提取纯化AChRab，然后用免疫组化法探讨AChRab与大鼠中枢神经-nAChR之间的免疫结合反应。结果首次表明，AChRab与神经-nAChR之间的阳性免疫结合反应广泛分布于大鼠大脑皮层、脑干颅神经运动核团、脊髓前角运动神经元等部位，提示MG患者AChRab不仅可与神经肌接头（NMJ）处肌-nAChR结合引起肌无力等症状，还可与CNS神经-nAChR结合，并可能引起CNS功能障碍。     

Anti-alkaline phosphatase antibody positive myasthenia gravis

Anti-alkaline phosphatase antibody (AP Ab) was specific in 9% of 249 anti-acetylcholine receptor (AChR) Ab-positive myasthenia gravis (MG) (SPMG) patients but not in patients with AChR Ab-negative MG (SNMG), other neurological and immunological diseases, or healthy volunteers. No cross-reactivity and no significant titer correlation were found between AP Ab and AChR Ab. We confirmed immunologically by radioimmunoassay and western blot analysis the presence of antibodies directed against AP. AP Ab-positive SPMG patients were characterized clinically as having female predominance and a more severe form of generalized MG than AP Ab-negative SPMG patients, and about half required artificial ventilation at maximum severity. AP Ab's pathogenic role in MG is yet unclarified, but our findings show AP to be a novel antigen among the various autoantigens present in MG patients and in whom AP Ab may modify clinical symptoms.     

抗体阴性重症肌无力发病与凝集素之间关系研究

借助研究抗体阴性重症肌无力（ＭＧ）发病与凝集素之间的关系，以阐明其发病过程是否与凝集素有关。方法观察伴刀豆球蛋白Ａ（ＣｏｎＡ）和麦胚凝集素（Ｔｒｉｔｉｃｕｍ）及其凝集素－糖复合物对ＴＥ６７１细胞表达的乙酰胆碱受体（ＡＣｈＲ）功能的作用，以及对α－ＢｕＴｘ结合试验的影响。结果有两种凝集素对ＡＣｈＲ功能均有抑制作用，抑制率（％）分别为５４±１４（ｎ＝１１）和４７±１６（ｎ＝１０），此作用可被３种糖抑制，抑制率（％）分别为：９５±５（ｎ＝５）和８４±８（ｎ＝５）；６９±６（ｎ＝４）和６５±５（ｎ＝４）；３９±４（ｎ＝５）和５７±６（ｎ＝５）；ＣｏｎＡ抑制α－ＢｕＴｘ结合试验，而Ｔｒｉｔｉｃｕｍ则不能。结论Ｔｒｉｔｉｃｕｍ和抗体阴性ＭＧ患者非ＩｇＧ部分对ＡＣｈＲ功能和α－ＢｕＴｘ结合试验的作用类同或一致，表明抗体阴性ＭＧ患者非ＩｇＧ部分中的内源性Ｔｒｉｔｉｃｕｍ样糖蛋白在其发病过程中起重要作用。     

Correlation of C3 level with severity of generalized myasthenia gravis

Acute exacerbation of generalized myasthenia gravis (GMG) can cause swallowing impairment, respiratory failure, or death. It is important to identify immunological factors that might be regarded reliably as an index of the patient's clinical condition, response to treatment, and measure of certain immune aberrations of MG. In this study we investigated correlations between complement component C3, acetylcholine receptor antibody (AChRab) titer, and clinical severity of GMG. AChRab titer and C3 concentration were determined by radioimmunoassay and nephelometry, respectively. The clinical severity of GMG was assessed by the quantitative MG score (QMGS) according to Besinger and colleagues. Our findings indicate that the C3 level correlates with clinical severity of AChRab‐positive GMG. Muscle Nerve, 2009     

Investigation for RAPSN and DOK-7 mutations in a cohort of seronegative myasthenia gravis patients

Introduction: Myasthenia gravis (MG) is an autoimmune disease. Patients without detectable antibodies against the nicotinic acetylcholine receptor or the muscle‐specific tyrosine kinase are referred to as seronegative MG (SNMG). Because late‐onset congenital myasthenic syndromes (CMSs) due to RAPSN or DOK7 mutations may be mistaken for SNMG, we investigated their frequency in a nationwide SNMG cohort. Methods: We performed sequencing of RAPSN and DOK7 in all Norwegian SNMG patients (n = 74) and 37 healthy controls, examining for the N88K and c.1124_1127dupTGCC mutations, respectively. Results: We found 1 patient homozygous for N88K and 2 carriers of the N88K mutation. Sequencing of DOK7 revealed no mutations. Conclusions: This study confirms that rapsn CMS can be mistaken for SNMG. In addition, the frequency of rapsn CMS in our nationwide SNMG cohort was found to be low. SNMG patients with an atypical clinical presentation and pediatric cases should be tested for the N88K mutation before initiation of immunosuppressive drug treatment or thymectomy. Muscle Nerve, 2011     

Clinical comparison of muscle-specific tyrosine kinase (MuSK) antibody-positive and -negative myasthenic patients

We assayed cryopreserved sera from 38 acetylcholine receptor (AChR) antibody-negative patients with myasthenia gravis (MG) who were followed clinically for muscle-specific tyrosine kinase (MuSK) antibodies and analyzed and compared their clinical characteristics. None of 13 sera from patients with purely ocular MG were positive. Sera from 10 of 25 patients (40%) with generalized MG were positive for MuSK antibodies. The age at onset of myasthenic symptoms was significantly earlier in MuSK antibody-positive patients (P = 0.02). MuSK antibodies were present in AChR antibody-negative patients of either gender, with virtually identical prevalence in women (41.2%) and men (37.5%). The distribution of weakness more commonly involved neck muscles in MuSK antibody-positive patients, and limb muscles in MuSK antibody-negative patients. Patients responded to immunosuppressive treatment regardless of whether MuSK antibody was present. We conclude that MuSK antibodies are present and diagnostically useful in a subset of myasthenic patients without AChR antibodies. Although the distribution of weakness differs somewhat depending on whether MuSK antibodies are present, responses to anticholinesterase and immunosuppressive treatments are similar.