胸腺与重症肌无力

重症肌无力(MG)作为一种典型的自身免疫性疾病,其发病与患者胸腺内发生的异常免疫反应密切相关,大约80%左右的MG患者胸腺异常,包括胸腺增生、胸腺瘤等。因此,探索MG的发生、发展及其与胸腺内发生的免疫反应之间的关系,可为MG的治疗提供实验依据和新的思路。现就胸腺细胞及其表达的分子与MG的相关性做一综述。     

天然调节性T细胞特性及以其为靶点治疗重症肌无力的研究进展

重症肌无力(MG)是一种细胞依赖性自身免疫性疾病,胸腺起源的CD4+T细胞的大量激活是MG发生的一个重要原因。天然调节性T细胞(nTreg)是一个具有独特免疫调节功能的CD4+调节性T细胞亚群,在自身免疫中发挥着重要作用。最近的研究发现nTreg与MG关系密切,针对nTreg来治疗MG是一种新的手段。本文就nTreg的特性及针对其治疗MG取得的成果做一综述。     

胸腺切除对重症肌无力患者T淋巴细胞亚型的影响

目的：观察胸腺切除(Tx)术对重症肌无力(MG)病人的临床疗效及对T淋巴细胞亚型的影响。方法：用许氏评分法观察30例伴胸腺增生或胸腺瘤的MG患者的病情严重程度及Tx术后2个月的临床疗效;采用直接免疫荧光染色和流式细胞仪技术测定60名志愿健康者和30例伴胸腺增生或胸腺瘤的MG患者Tx术前及术后2个月T淋巴细胞亚型的变化。结果：伴胸腺增生或胸腺瘤的MG病人Tx术前外周血中CD4＋T淋巴细胞的百分率较正常人显著增多(P＜0．01),CD8＋T淋巴细胞的百分率较正常人显著减少(P＜0．01),CD4＋/CD8＋T细胞的比例明显增高(P＜0．01)。伴胸腺增生MG病人Tx术后随着临床症状的改善,CD8＋T淋巴细胞的百分率较术前显著升高(P＜0．05),CD4＋/CD8＋T细胞的比例较术前显著下降(P＜0．05)。伴胸腺瘤MG病人Tx术后随着临床症状的改善,CD4+T淋巴细胞的百分率较术前显著下降(P＜0．05),CD4＋/CD8＋T细胞的比例较术前显著下降(P＜0．05)。结论：重症肌无力患者T淋巴细胞亚型的测定既可以为MG免疫病理学的发病机理的研究提供实验依据,也能为Tx治疗MG提供一个客观的实验室指标,为判断疾病的转归提供实验依据。     

FoxP3+ CD4+ CD25+调节性T细胞在重症肌无力发病机制中的作用

目的 在细胞与分子水平检验重症肌无力(myasthenia gravis,MG)患者外周血中CD4+CD25+调节性T细胞(CD4+CD25+Tregs)的表达缺陷,探讨CD4+CD25+Tregs亚群异常与MG发病间的关系.方法 流式细胞技术检测21例MG患者(11例经胸腺切除)与20名健康对照者(healthy controls,HCs)外周血CD4+CD25+Tregs及FoxP3+CD4+CD25+Tregs含量,实时荧光定量聚合酶链反应(RT-FQ-PCR)分析MG患者与HCs外周血CD4+CD25+Tregs中FoxP3 mRNA的表达.结果 MG患者外周血CD4+CD25+ Tregs占CD4+T细胞含量与HCs比较无统计学差异(P＞0.05).MG患者外周血FoxP3+CD4+CD25+ Tregs含量及FoxP3 mRNA表达量与HCs比较均显著性降低(P＜0.05);胸腺切除的MG患者与未经胸腺切除的MG患者外周血FoxP3+CD4+CD25+ Tregs含量及FoxP3mRNA表达量无统计学差异(P＞0.05).结论 MG患者外周血CD4+CD25+ Tregs数量正常,但其表面分子FoxP3的表达下调,这种CD4+CD25+ Tregs亚群的异常发现有助于深入阐明MG的免疫发病机制.     

胸腺切除术后重症肌无力复发或疗效不佳的危险因素

重症肌无力(MG)是一类以自身抗体所介导、发生在神经-肌肉接头处、以部分或全部骨骼肌波动性无力为表现的自身免疫性疾病。MG患者大多数合并胸腺异常,包括胸腺增生和胸腺瘤。目前认为异常胸腺是MG患者自身抗体产生的重要场所,切除异常胸腺是治疗MG的有效手段,甚至有报道切除正常的胸腺,也会改善MG患者肌无力症状。然而,关于胸腺切除术后MG复发的报道越来越多,原因尚不明确。目前研究发现患者发病年龄、病程、美国MG基金会(MGFA)分型、胸腺病理类型、Masaoka分级、是否合并其他自身免疫性疾病等因素均可能影响胸腺切除术后MG复发或疗效不佳。     

伴胸腺瘤重症肌无力发病机制研究进展

重症肌无力(myasthenia gravis,MG)是以胸腺为靶器官的器官特异性自身免疫性疾病,伴胸腺瘤MG与不伴胸腺瘤MG发病机制不同。近年来发现伴胸腺瘤MG在T细胞数量和功能、自身抗体的种类以及遗传学等方面与不伴胸腺瘤MG存在差异。本文旨在结合文献从胸腺微环境、T细胞发育、自身抗体及遗传学等方面在伴胸腺瘤MG发病机制中作用进行综述。     

S-100、HLA-DR双阳性树突状细胞在重症肌无力患者胸腺中的变化

目的:探讨胸腺S-100、HLA-DR双阳性树突状细胞在重症肌无力(MG)发病中的作用。方法:采用免疫荧光双标法对16例MG 患者(伴胸腺瘤或胸腺增生)、11例非MG患者(单纯胸腺瘤或增生)、5例正常胸腺组织中S-100、HLA-DR双阳性树突状细胞进行检测,同时用HE染色进行形态学观察。结果:①S-100、HLA-DR双阳性树突状细胞主要分布在胸腺皮质、皮髓交界处,MG胸腺在髓质也有一定量分布。MG组部分DCs在靠近血管附近有聚集趋势。②S-100、HLA-DR双阳性树突状细胞数量在MG患者与非MG患者间,MG患者与正常胸腺之间有显著性差异;而在MG伴胸腺瘤和伴胸腺增生患者间差异不显著。③HLA-DR分子在MG患者胸腺树突状细胞中高表达,主要分布于树突状细胞的胞质,少数表达于细胞膜上。结论:胸腺S-100、HLA-DR双阳性树突状细胞以多种形式参与MG发病,以抗原提呈为主,HLA-DR可能在胸腺阴性选择中有一定影响。     

重症肌无力胸腺基质淋巴细胞生成素表达与CD4~+CD25~+Foxp3~+Treg细胞表型的研究

目的探索重症肌无力患者胸腺基质淋巴细胞生成素(TSLP)表达水平与CD4+CD25+Foxp3+调节性T细胞(Treg)表型的相关性。方法 MG组(16例经胸腺切除的MG患者)及对照组(23例先天性心脏病心脏手术后患者)取外周血单个核细胞,经CD4+CD25+抗体表面染色后加入破膜剂孵育,以Foxp3+抗体行胞内染色,以流式细胞技术检测CD4+CD25+Foxp3+Treg/CD4+T细胞比率;同时取两组患者对应的切除胸腺组织,以免疫组织化学法检测TSLP表达水平,并进行两组间比较;以Logistic回归分析方法分析TSLP阳性表达的Hassall小体计数与Treg细胞之间的相关性。结果CD4+CD25+/CD4+T细胞比率MG组〔(6.24±0.62)%〕与对照组〔(6.56±0.65)%〕无统计学差异(P>0.05),MG组CD4+CD25+Foxp3+Treg/CD4+T细胞比率〔(3.82±0.49)%〕较对照组〔(5.73±0.56)%〕明显降低(P<0.01);与对照组比较,MG组患者胸腺TSLP阳性面积大,染色深,且TSLP阳性的Hassall小体数目(6.81±2.17)明显低于对照组(18.87±3.06)(P<0.01)。MG组TSLP阳性表达的Hassall小体计数与Treg细胞表达量之间呈线性相关(R2=0.158,F=13.42,P<0.01)。结论 MG患者TSLP表达不足与胸腺Treg细胞发育过程中CD4+CD25+Foxp3+表型的表达缺陷呈正相关。     

重症肌无力免疫学发病机制研究进展

重症肌无力(MG)是典型的由抗体介导、T细胞依赖、补体参与的器官特异性自身免疫性疾病,其发病的关键在于机体自我耐受的打破,产生针对自身抗原乙酰胆碱受体的异常免疫应答。胸腺、T细胞、补体及补体调节因子、B细胞均在MG发病中发挥一定作用,现分别就其在MG发病机制中的作用研究进行综述。     

重症肌无力的发病机制

重症肌无力(MG)是一种神经-肌肉接头传递功能障碍的自身免疫性疾病。MG的发病机制主要涉及免疫因素和遗传因素。免疫因素包括多种致病抗体、细胞免疫、细胞因子、补体及胸腺等。随着免疫学研究的不断进展,MG的发病机制也有了更深入的研究。     

免疫抑制剂对重症肌无力病人T淋巴细胞亚型的影响

目的观察重症肌无力(MG)病人细胞免疫的异常改变和免疫抑制剂对重症肌无力(MG)病人的临床疗效及对T淋巴细胞亚型的影响。方法用许氏评分法观察60例MG病人的病情严重程度和免疫抑制治疗2个月后的临床疗效;采用直接免疫荧光染色和流式细胞仪技术测定60例病人和60名志愿健康者周围血中T淋巴细胞亚型的百分率,并测定糖皮质激素或环磷酰胺免疫抑制治疗前及治疗后2个月T淋巴细胞亚型的变化。结果未治疗MG组外周血中CD8 T淋巴细胞的百分率较正常对照组显著下降(P<0.01);CD4 T淋巴细胞的百分率和CD4 /CD8 T细胞的比例较正常对照组均显著升高(P<0.01)。经激素或环磷酰胺治疗2个月后MG组随着临床症状的改善,外周血中总T细胞(CD3 )和CD8的百分率较治疗前均显著升高(P<0.01;P<0.05);CD4 T淋巴细胞的百分率和CD4 /CD8 T细胞的比例较治疗前均显著下降(P<0.01)。结论MG病人有T淋巴细胞亚型的变化,免疫抑制治疗对T淋巴细胞亚群有明显影响,提示T淋巴细胞亚型的测定可为激素、环磷酰胺等免疫疗法提供一个客观的实验室指标,为判断疾病的转归提供实验依据。     

Evidence against chronic antigen-specific T lymphocyte activation in myasthenia gravis

Myasthenia gravis (MG) is an antigen-specific autoimmune disease caused by antibodies against acetylcholine receptors (AChR) at the post-synaptic membrane of the neuromuscular junction. Clinical and immunological data imply the involvement of AChR-specific T lymphocytes as helper cells for autoantibody production. Direct data to support this hypothesis, however, remain sparse. In the present study, a large population of MG patients was studied for evidence of peripheral blood T cell activation by several assays. Assays based on non-specific measurements of T cell activation as well as assays of antigen-specific clonal expansion were utilized. Levels of soluble IL-2 receptor in serum were modestly elevated in some patients, suggesting T cell activation. However, peripheral blood cells did not show evidence of IL-2 receptor expression or enhanced reactivity to IL-2 in culture. Clonable T cells selected for hypoxanthine phosphoribosyl transferase (hprt) mutation, another non-antigen-specific marker for T cell activation, were not seen with increased frequency except in patients treated with purine analogs. Antigen-specific T cell activation was measured by proliferation assays using heterologous and autologous sources of AChR. Antigen-restimulated peripheral blood cell cultures were cloned by limiting dilution. The vast majority of patients failed to show convincing evidence of AChR specific T cell activation or clonal expansion; only 2 of 44 patients demonstrated clonable autologous AChR-specific T cells. An alternative hypothesis of T cell involvement in MG is proposed in which T cell activation is discontinuous and predominately directed at antigens other than AChR. © 1996 Wiley-Liss, Inc.     

重症肌无力患者外周血T淋巴细胞亚群凋亡的研究

目的探讨外周血T淋巴细胞亚群凋亡在重症肌无力(MG)免疫发病机制中的作用及临床意义。方法采用流式细胞术结合免疫荧光抗体法测定了45例MG患者和40例正常对照组外周血CD4~ T淋巴细胞、CD8~ T淋巴细胞百分数及其凋亡状况,并对24例MG患者在应用糖皮质激素治疗后外周血T淋巴细胞亚群凋亡状况进行了观察。结果MG患者组外周血CD8~ T淋巴细胞百分率较正常对照组明显降低,CD4~ /CD8~ 比值较正常对照组明显升高：MG患者组外周血CD4~ T淋巴细胞凋亡程度较正常对照组明显降低；MG患者外周血CD4~ T淋巴细胞凋亡程度与MG类型、预后密切相关：应用糖皮质激素治疗后MG患者外周血CD4~ T淋巴细胞凋亡程度明显增强。结论MG患者存在T淋巴细胞亚群的分布异常及CD4~ T淋巴细胞凋亡功能障碍,其凋亡程度可能与MG类型、预后密切相关,糖皮质激素对MG患者外周血CD4~ T淋巴细胞凋亡缺陷具有纠正作用。     

Inhibition of peripheral blood natural killer cell cytotoxicity in patients with myasthenia gravis treated with plasmapheresis

Background and purpose: Myasthenia gravis (MG) is an autoimmune disorder that may involve natural killer (NK) cells. Although NK cells are part of the innate immune system, they also influence adaptive immune responses. Double‐filtration plasmapheresis (DFP) is an effective therapy for MG crisis. Thus, we examined the effects of DFP on the cytotoxicity of NK cells. Methods: A total of 20 patients with MG and 16 healthy controls were recruited for the study. Ficoll‐Paque‐isolated peripheral blood mononuclear cells (PBMCs) and K562 cells were used as the effector and target cells, respectively. NK cell cytotoxicity was analyzed using flow cytometry immediately before and after DFP and upon course completion. Results: Double‐filtration plasmapheresis treatment decreased significantly the NK cell cytotoxicity in patients with MG, especially in good responders, those who were positive for acetylcholine receptor (AChR) antibodies, and those receiving immunosuppressants. Conclusions: The decrease in NK cell cytotoxicity after DFP and the decline of AChR antibody titer were observed in good responders indicating that this could benefit patients with MG.     

Effects of oxygen-glucose deprivation on microglial mobility and viability in developing mouse hippocampal tissues

As brain‐resident immune cells, microglia (MG) survey the brain parenchyma to maintain homeostasis during development and following injury. Research in perinatal stroke, a leading cause of lifelong disability, has implicated MG as targets for therapeutic intervention during stroke. Although MG responses are complex, work in developing rodents suggests that MG limit brain damage after stroke. However, little is known about how energy‐limiting conditions affect MG survival and mobility (motility and migration) in developing brain tissues. Here, we used confocal time‐lapse imaging to monitor MG viability and mobility during hypoxia or oxygen‐glucose deprivation (OGD) in hippocampal tissue slices derived from neonatal GFP‐reporter mice (CX3CR1^GFP/+). We found that MG remain viable for at least 6 h of hypoxia but begin to die after 2 h of OGD, while both hypoxia and OGD reduce MG motility. Unexpectedly, some MG retain or recover motility during OGD and can engulf dead cells. Additionally, MG from younger neonates (P2–P3) are more resistant to OGD than those from older ones (P6–P7), indicating increasing vulnerability with developmental age. Finally, transient (2 h) OGD also increases MG death, and although motility is rapidly restored after transient OGD, it remains below control levels for many hours. Together, these results show that MG in neonatal mouse brain tissues are vulnerable to both transient and sustained OGD, and many MG die within hours after onset of OGD. Preventing MG death may, therefore, provide a strategy for promoting tissue restoration after stroke. © 2012 Wiley Periodicals, Inc.     

Specific immunotherapeutic strategy for myasthenia gravis: targeted antigen-presenting cells

The pathogenesis of myasthenia gravis (MG) involves a T cell-dependent antibody-mediated autoimmune response directed against acetylcholine receptors (AChR). Inactivation of AChR-specific T cells should interrupt the immune response, resulting in therapeutic benefit. Since each individual's repertoire of T cells responds to a heterogeneous and unique spectrum of AChR epitopes presented in association with self-major histocompatibility complex (MHC) class II, an individualized approach is required to target all relevant AChR-specific T cells. The individual's own antigen-presenting cells (APC) can be used for this purpose, since they process and present the antigen appropriately, and express the correct MHC class II. A novel method of binding AChR to surface immunoglobulin with a heterobifunctional antibody conjugate allows us to use all B cells as APC. Conjugate-plus-AChR-treated B cells (AChR-APC) effectively targeted AChR-specific T cells, stimulating vigorous proliferative responses in a rat cell culture system. If APCs are 'fixed' with cross-linking reagents, they induce long-lasting or permanent 'anergy' of the specific T cells. We prepared AChR-APC, allowed them to process AChR in vitro, and fixed them with paraformaldehyde. Pre-culture of these fixed AChR-APC with AChR-specific T cells induced anergy: when restimulated with fresh AChR-APC, the T cells exhibited markedly reduced proliferative responses and IL-2 production, compared with responses of T cells pre-cultured with control fixed B cells. Implications for the design of antigen-specific therapeutic strategies for MG and other immune disorders will be discussed.     

重症肌无力患者外周血AIRE、Tfh细胞和Tfr细胞与病情严重性相关分析

目的探讨自身免疫性调节因子(AIRE)、滤泡辅助性T(Tfh)细胞和滤泡调节性T(Tfr)细胞与重症肌无力(MG)患者病情严重程度的相关性。方法收集2015-12—2016-4第四军医大学唐都医院收治的MG患者22例,根据临床表现分为全身型MG(GMG)和眼肌型MG(OMG);同期选取健康体检中心查体者10名作为健康对照。收集MG患者详细临床资料,包括美国MG协会(MGFA)分型及定量MG(QMG)评分。通过流式细胞术分析AIRE阳性细胞比例及Tfh/Tfr比值。结果 (1)AIRE表达在各组间比较差异具有统计学意义(P0.01)。GMG组和OMG组AIRE表达均较对照组降低(P0.01,P0.05),而GMG组与OMG组间比较差异无统计学意义(P0.05)。(2)Tfh/Tfr比值在各组间比较差异具有统计学意义(P0.01)。GMG组和OMG组Tfh/Tfr比值均高于对照组(P0.01,P0.05),且GMG组高于OMG组(P0.05)。(3)MG患者AIRE表达与MGFA分型及QMG评分呈负相关(r=-0.517,P0.05;r=-0.616,P0.01),Tfh/Tfr比值与MGFA分型和QMG评分呈正相关(r=0.761,r=0.581,均P0.01)。结论 AIRE、Tfh/Tfr比值与MG的病情严重程度有一定的相关性,并可能参与了MG的发病。     

大剂量免疫球蛋白及肾上腺皮质激素治疗重症肌无力比较

目的为研究免疫球蛋白对重症肌无力（ＭＧ）的治疗效果,对６２例ＭＧ患者进行了免疫球蛋白及肾上腺皮质激素治疗的对比研究。方法３２例ＭＧ患者静脉注射大剂量免疫球蛋白（ＩＶＩｇ）,３０例ＭＧ患者应用了肾上腺皮质激素（ＡＣＳ）冲击治疗。临床绝对评分及相对评分作为治疗前后疗效判定标准。结果６２例ＭＧ患者治疗前后评分有明显差异（Ｐ＜０．０１）,ＡＣＳ治疗前后差值较ＩＶＩｇ明显加大（Ｐ＜０．０１）。结论ＩＶＩｇ治疗ＭＧ有效,ＡＣＳ治疗ＭＧ效果优于ＩＶＩｇ。ＩＶＩｇ可作为治疗ＭＧ的二线药物。     

重症肌无力患者细胞免疫水平的检测及临床意义

目的 :探讨周围血中 T细胞亚群、NK细胞、细胞膜白细胞介素 - 2受体、可溶性白细胞介素 - 2受体的阳性细胞与 MG发病及临床疗效的关系。方法 :1.应用流式细胞仪检测外周围血 m IL- 2 R(CD2 5)阳性细胞、NK(CD5 6 )和T细胞亚群 (CD3 、CD4、CD8)的相对计数。 2 .用富氏双抗体夹心 EL ISA方法检测血清 s IL- 2 R。结果 :1.MG患者血清s IL- 2 R水平明显高于健康对照组 ,激素治疗后较治疗前明显下降 ;2 .NK和 CD4阳性细胞在治疗前均明显高于正常 ,治疗后明显下降 ;3.CD3 阳性细胞在激素治疗前后无明显改变 ;4.m IL- 2 R(CD2 5)阳性细胞数无明显改变。结论 :1.血清中的 s IL- 2 R,NK细胞的测定可对该病进行动态观察 ;2 .CD4增高 ,CD8下降提示免疫功能紊乱 ;3.m IL- 2 R阳性细胞百分率不能直接反映 MG的免疫功能紊乱。