Abstract
目的
比较不同肌炎特异性自身抗体(myositis specific antibodies,MSAs)类型的免疫介导坏死性肌病(immune-mediated necrotizing myopathies,IMNM)的临床和病理特征。
方法
从中日友好医院2008—2018年住院期间所有行肌肉活检的特发性炎性肌病患者中选取符合以下任一条件的IMNM患者104例:(1)抗信号识别颗粒(signal recognition particle,SRP)抗体阳性;(2)抗3-羟基-3-甲基戊二酰辅酶A 还原酶(3-hydroxy-3-methylglutaryl-coenzyme A reductase,HMGCR)抗体阳性;(3)血清MSAs阴性且病理符合2004年欧洲神经肌肉病中心定义的IMNM病理诊断标准。回顾性收集患者的临床、实验室检查和肌肉病理等信息,比较各组临床及病理特征的差异。
结果
所有104例IMNM患者中,肌无力(92.3%)、肌酸激酶升高(92.3%)是IMNM的最常见临床表现,此外,33.7%的IMNM患者合并吞咽困难,46.5%的患者合并间质性肺病(interstitial lung diseases,ILD)。抗HMGCR阳性患者较抗SRP阳性和MSAs阴性患者更容易出现V形疹(30.4% vs. 4.3%和5.9%,P<0.01),抗SRP阳性患者合并ILD发生率高于抗HMGCR阳性和MSAs阴性患者(64.4% vs. 34.8%和29.0%,P<0.01),MSAs阴性患者合并其他结缔组织病更多见(32.4% vs. 8.5%和4.3%,P<0.01)。3组IMNM患者肌肉病理中均可见肌细胞坏死(94.2%)、吞噬(65.4%)和再生(67.3%),肌细胞膜表达主要组织相容性复合物-Ⅰ分子上调(78.8%),肌内膜CD4 +T细胞(68.3%)和CD68+巨噬细胞(65.7%)浸润。
结论
抗SRP抗体阳性、抗HMGCR抗体阳性和MSAs阴性的IMNM患者存在异质性,在临床上开展MSAs检测和肌肉病理检查对区分不同类型的IMNM有指导价值。
Keywords: 肌炎, 自身免疫病, 信号识别颗粒, 羟甲基戊二酰基CoA还原酶, 病理学
Abstract
Objective
To investigate the clinical and pathological features of immune-mediated necro-tic myopathies (IMNM) with different myositis-specific antibodies (MSAs).
Methods
In the study, 104 IMNM patients who met any of the following three criteria were selected from idiopathic inflammatory myopathy patients who had MSAs results and underwent muscle biopsy from 2008 to 2018 in China-Japan Friendship Hospital: (1) Anti-signal recognition particle (SRP) antibody positive; (2) Anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) antibody positive; (3) MSAs negative and consistent with the pathological diagnostic criteria of IMNM defined by the European Neuromuscular Centre in 2004. The clinical, laboratory and muscle pathological information of the IMNM patients were retrospectively collected and compared in anti-SRP, anti-HMGCR and MSAs negative groups.
Results
Of 104 IMNM patients, 47 patients (45.2%) were positive for anti-SRP antibody, 23 (22.1%) were positive for anti-HMGCR antibody, and 34 (32.7%) were negative for MSAs. The common symptoms of IMNM patients were muscle weakness (92.3%), elevated serum creatine kinase level (92.3%), dysphagia (33.7%) and interstitial lung diseases (ILD) (49.5%). The anti-HMGCR-positive patients were more frequent to have “V” sign (30.4% vs. 4.3% and 5.9%, P<0.01) as compared with the anti-SRP-positive and MSAs-negative patients. The incidence of ILD in the anti-SRP-positive patients was higher than that in the anti-HMGCR-positive and MSAs negative patients (64.4% vs. 34.8% and 29.0%, P<0.01). The prevalence of the patients combined with other connective tissue diseases in MSAs-negative IMNM was higher than that in the other two groups (32.4% vs. 8.5% and 4.3%, P<0.01). 93.3% of the anti-SRP-positive patients were found with antinuclear antibody positivity, higher than those of the anti-HMGCR-positive and MSAs-negative patients (93.3% vs. 36.4% and 58.8%, P<0.001). The common pathological features of IMNM were muscle fibre necrosis (94.2%), regeneration (67.3%) and phagocytosis (65.4%), overexpression of major histocompatibility complex-1 on sarcolemma (78.8%), infiltration of CD4 + T cells (81.7%) and CD68+ macrophage (79.8%) and expression of membrane attack complex (MAC) (77.8%). The endomysial infiltration of CD4+ T cells and CD68+ macrophage and MAC expression on sarcolemma in the MSAs-negative group were more common than that in the anti-SRP and anti-HMGCR groups (88.2% vs. 57.4% and 60.9%, 91.2% vs. 59.1% and 38.1%, 76.5% vs. 45.5% and 42.9%, respectively, P<0.01).
Conclusion
There is heterogeneity in anti-SRP-positive, anti-HMGCR-positive or MSAs-negative patients. The detection of MSAs and performing of muscle biopsy are useful for distinguishing different types of IMNM.
Keywords: Myositis, Autoimmune diseases, Signal recognition particle, Hydroxymethylglutaryl CoA reductases, Pathology
免疫介导坏死性肌病(immune-mediated necrotizing myopathies,IMNM)是2004年欧洲神经肌肉病中心(European Neuromuscular Centre,ENMC)提出的特发性炎性肌病(idiopathic inflammatory myositis,IIM)中一种不同于多发性肌炎(polymyositis,PM)和皮肌炎(dermatomyositis,DM)的独立亚型,病理特征以肌组织中大量坏死肌细胞、少或无炎症细胞浸润为主要改变,临床上表现为显著肌酸激酶(creatine kinase,CK)升高和肌无力[1,2,3],为区别该类型在病理特征上与PM和DM的不同,将其定义为IMNM。现有的研究提示,肌炎特异性自身抗体(myositis-specific autoantibodies,MSAs)中抗信号识别颗粒(signal recognition particle,SRP)抗体和抗3-羟基-3-甲基戊二酰辅酶A 还原酶(3-hydroxy-3-methylglutaryl-coenzyme A reductase,HMGCR)抗体是IMNM的血清标记物[2,3],但仍有一部分MSAs阴性的IIM患者的病理特征符合2004年ENMC定义的IMNM标准[4]。目前,尚不清楚这些不同血清型的IMNM在临床和病理特征上有何异同,本研究的目的即是探讨不同血清学特征的IMNM之间临床和病理特征的差异,为完整和准确定义IMNM提供依据。
1. 资料与方法
1.1. 研究对象
选取中日友好医院2008—2018年住院期间行肌肉活检的所有患者,并根据1975年 Bohan和 Peter的IIM诊断标准[5,6],在IIM患者中选取符合IMNM的患者104例。IMNM的纳入标准包括如下3条,符合其中任一条者纳入本研究:(1)血清抗SRP抗体阳性;(2)血清抗HMGCR抗体阳性;(3)血清MSAs阴性且符合2004年ENMC定义的IMNM病理诊断标准:肌细胞坏死,肌组织中无或较少的炎症细胞浸润,膜攻击复合物(membrane attack complex,MAC)在毛细血管壁上沉积,无肌细胞内包涵体[1]。本研究获中日友好医院临床研究伦理委员会批准(2016-ST-5),所有患者均签署知情同意书。
1.2. 临床数据收集
收集患者的人口学信息、临床资料、实验室检查结果、肌肉活检病理结果等信息。慢性病程定义为病程大于12个月[7],严重肌无力定义为医学研究委员会六级肌力评分法评估最差肌力≤3级[8],肌肉萎缩定义为肌肉磁共振T1加权序列提示有肌肉的脂肪替代。恶性肿瘤诊断均有组织病理(穿刺或手术切除)证实,间质性肺病(interstitial lung diseases,ILD)定义为胸部高分辨率CT提示肺内磨玻璃影、网格影蜂窝状等改变[9,10],其他结缔组织病包括类风湿关节炎、系统性红斑狼疮、系统性硬化和干燥综合征等。
1.3. MSAs检测
患者血清保存于-80 ℃冰箱,使用欧盟肌炎抗体免疫印迹试剂盒(欧盟公司,德国)对MSAs和肌炎相关抗体进行检测,包括抗SRP抗体、抗Mi-2α抗体、抗Mi-2β抗体、抗转录中介因子1-γ抗体、抗黑色素瘤分化相关基因5抗体、抗核基质蛋白2抗体、抗小泛素修饰物活化酶抗体、抗组氨酰tRNA合成酶抗体、抗苏氨酰tRNA合成酶抗体、抗丙氨酰tRNA合成酶抗体、抗甘氨酰tRNA合成酶抗体、抗异亮氨酸tRNA合成酶抗体、抗Ro-52抗体、抗PM-Scl 75抗体、抗PM-Scl 100抗体、抗Ku抗体等。抗HMGCR抗体的检测采用酶联免疫吸附法(瑞博奥生物科技有限公司,广州)。上述检测方法均参照试剂盒说明书方法。
1.4. 肌肉病理检测
全部患者的肌肉活检标本均为开放肌活检术在局部麻醉下取肱二头肌获得。新鲜肌活检标本经液氮预冷却的异戊烷速冻,恒冷箱冰冻切片(Thermo Cryotome E)制成7 μm冰冻切片,于丙酮4 ℃固定15 min,Triton X-100 浸洗3次,每次5 min,置于-80 ℃备用。苏木素-伊红染色后,采用亲和素-生物素-过氧化物酶复合物法行主要组织相容性复合物(major histocompatibility complex MHC)-Ⅰ、CD4、CD8、CD20、CD68和MAC的免疫组织化学染色。所用试剂均购自Abcam公司。所有肌肉病理标本分析均由有经验的病理医生和风湿科医生共同进行,肌肉活检标本记录以下几个方面的病理特征:肌细胞坏死、再生和吞噬,肌内膜和/或肌束膜结缔组织有无增生,肌细胞膜表达MHC-Ⅰ分子,肌组织中CD4+ T细胞、CD8+ T细胞、CD20+ B细胞和CD68+巨噬细胞的浸润及MAC沉积。
1.5. 统计学分析
采用SPSS 24.0统计软件对数据进行分析。分类变量用频数(%)表示,服从正态分布的数值变量用均值±标准差表示,不服从正态分布的数值变量用中位数(四分位间距)表示。分类变量用卡方检验、Fisher’s精确检验进行统计,数值变量用t检验、Mann-Whitney检验进行显著性分析,P<0.05为差异有统计学意义。若3组间P<0.05,两组间比较用Bonferroni法进行校正,两组间P<0.017差异有统计学意义。
2. 结果
2.1. IMNM的临床特征
本研究共纳入104例IMNM患者,女性占70.2%,发病年龄15~85岁,病程(20.85±27.79)个月,56.7%的患者为慢性病程。其中47例(45.2%)患者抗SRP抗体阳性,23例(22.1%)患者抗HMGCR抗体阳性,MSAs阴性患者34例(32.7%), 具体临床特征见表1。
1.
IMNM不同抗体组临床特征的比较
Comparisons of clinical features of different serological subgroups of IMNM
| Features | IMNM(n=104) | Anti-SRP(n=47) | Anti-HMGCR(n=23) | MSAs negative(n=34) | P |
| ILD, interstitial lung diseases; CTD, connective tissue diseases; IMNM, immune mediated necrotizing myopathies; SRP, signal recognition particle; HMGCR, 3-hydroxy-3-methylglutaryl-coenzyme A reductase; MSAs, myositis specific autoantibodies. Data are shown as n(%) and x±s. * P<0.017, between anti-HMGCR group and anti-SRP /MSAs negative group; # P<0.017, between anti-SRP and anti-HMGCR/MSAs negative group; △ P<0.017, between MSAs negative and anti-SRP/anti-HMGCR group. | |||||
| Female | 73 (70.2) | 38 (80.9) | 13 (56.5) | 22 (64.7) | 0.078 |
| Age/years | 46.24±15.38 | 47.49±15.76 | 46.09±18.08 | 44.62±12.02 | 0.712 |
| Age of onset/years | 44.63±16.03 | 46.11±16.21 | 44.13±20.83 | 42.91±11.82 | 0.671 |
| Duration/months | 20.85±27.79 | 19.01±25.08 | 25.5±35.03 | 10.23±26.36 | 0.652 |
| Chronic progression (>12 months) | 59 (56.7) | 28 (59.6) | 12 (52.2) | 19 (55.9) | 0.836 |
| Fever | 5 (4.8) | 3 (6.4) | 1 (4.3) | 1 (2.9) | 0.763 |
| Loss of weight | 31 (29.8) | 14 (29.8) | 4 (17.1) | 13 (32.8) | 0.241 |
| Muscle weakness | 96 (92.3) | 44 (93.6) | 21 (91.3) | 31 (91.1) | 0.902 |
| Severe muscle weakness | 48 (46.2) | 22 (46.8) | 9 (39.1) | 17 (50.0) | 0.716 |
| Muscle atrophy | 15/73(20.5) | 5/33 (15.6) | 4/17 (23.5) | 6/24 (25.0) | 0.651 |
| Myalgia | 29 (27.9) | 13 (27.7) | 8 (34.8) | 8 (23.5) | 0.649 |
| Arthritis | 10 (9.6) | 4 (8.5) | 1 (4.3) | 5 (14.7) | 0.404 |
| Skin involvement | 27 (26.0) | 12 (25.5) | 8 (34.8) | 7 (20.6) | 0.485 |
| Heliotrope rash | 7 (7.7) | 3 (6.4) | 2 (8.7) | 3 (8.8) | 0.902 |
| Gottron’s sign | 2 (1.9) | 1 (2.1) | 0 | 1 (2.9) | 0.723 |
| “V” sign | 11 (10.6) | 2 (4.3) | 7 (30.4) | 2 (5.9) | 0.002* |
| Shawl sign | 6 (5.8) | 2 (4.3) | 4 (17.4) | 0 | 0.018 |
| Raynaud phenomenon | 4 (3.8) | 3 (6.4) | 0 | 1 (2.9) | 0.404 |
| ILD | 46/99 (46.5) | 29/45 (64.4) | 7/23 (30.4) | 10/31 (29.0) | 0.004# |
| Cough | 2/46 (4.3) | 2/29 (6.9) | 0/7 | 0/10 | 0.542 |
| Dyspnea | 4/46 (8.7) | 3/29 (10.3) | 0/7 | 1/10 (10.0) | 0.675 |
| Asymptomatic | 41/46 (89.1) | 25/29 (86.2) | 7/7 (100.0) | 9/10 (90.0) | 0.572 |
| Dysphagia | 35 (33.7) | 17 (36.2) | 8 (34.8) | 10 (29.4) | 0.576 |
| Cancer | 4 (3.8) | 3 (6.4) | 1 (4.3) | 0 | 0.334 |
| With other CTD | 16 (15.4) | 4 (8.5) | 1 (4.3) | 11 (32.4) | 0.003△ |
| Death | 5 (4.8) | 3 (6.4) | 1 (4.3) | 1 (2.9) | 0.769 |
104例IMNM患者中,92.3%患者有肌无力表现,其中46.2%的患者出现严重肌无力,但抗SRP抗体组、抗HMGCR抗体组和MSAs阴性组间严重肌无力患者比例差异无统计学意义。抗HMGCR抗体阳性的患者较抗SRP抗体阳性和MSAs阴性患者更容易出现V形疹(30.4% vs. 4.3%和5.9%, χ2=7.994,P=0.002)。抗SRP抗体阳性患者合并ILD的发生率高于抗HMGCR抗体阳性者和MSAs阴性患者(64.4% vs. 34.8%和29.0%, χ2=10.897,P=0.004)。尽管合并ILD患者比例在所有IMNM患者中达46.5%,但 89.1%的ILD患者为无症状性ILD。4例IMNM患者确诊恶性肿瘤,5例患者死亡,其中3例抗SRP抗体炎性的患者分别确诊胃癌、膀胱癌和霍奇金淋巴瘤,3例抗SRP抗体阳性患者和1例MSAs阴性患者死于呼吸衰竭,1例抗HMGCR抗体阳性患者确诊并死于宫颈癌。22例(19.8%)患者合并有其他结缔组织病,MSAs阴性的IMNM患者合并有其他结缔组织病比例高于抗SRP和抗HMGCR阳性组(32.4% vs. 8.5%和4.3%, χ2=11.378,P=0.003)。
2.2. 各组间IMNM的实验室特征
92.4%的IMNM患者均有CK升高,最高CK值为5 100(2 749, 9 916) IU/L,其中抗HMGCR组最高,达5 728(3 320,11 435) IU/L,MSAs阴性组最低,为4 827(1 324, 9 831) IU/L,但3组间差异并无统计学意义。抗SRP抗体阳性的患者较抗HMGCR抗体阳性和MSAs阴性的患者血清中更易检出抗核抗体(anti-nuclear antibody,ANA)阳性(93.3% vs. 36.4%和58.8%, χ2=25.192,P<0.001)。抗SRP抗体阳性的患者中88.9%的ANA核型为胞浆颗粒型,其中80%(36/45)的患者ANA滴度大于等于 1 :160,仅有31.8%的抗HMGCR抗体阳性的患者ANA滴度大于等于1 :80,近40%的MSAs阴性患者血清中可检测到ANA滴度大于等于1 :160(表2)。
2.
IMNM不同抗体组实验室特征比较
Comparisons of laboratory characteristics of different serological subgroups of IMNM
| Features a | IMNM (n=104) | Anti-SRP (n=47) | Anti-HMGCR (n=23) | MSAs negative (n=34) | P |
| ANA, anti-nuclear antibodies; ALT, alanine aminotransferase; AST, aspartate aminotransferase; LDH, lactic dehydrogenase; CK, creatine kinase; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; Fet, serum ferritin; other abbreviations as in Table 1. a, normal value in brackets. Data are shown as n(%) and median (IQR). * P<0.017, between anti-SRP and anti-HMGCR/MSAs negative group; # P<0.017, between anti-SRP and anti-HMGCR group; △ P<0.05, between anti-SRP and MSAs negative group. | |||||
| Anti-Ro-52 | 25 (24.0) | 16 (34.0) | 1 (4.3) | 8 (23.5) | 0.024 |
| ANA | 74/101 (73.3) | 42/45 (93.3) | 8/22 (36.4) | 20/34 (58.8) | <0.001* |
| Peak CK/(IU/L) | 5 100 (2 749, 9 916) | 5 070 (2 975, 9 994) | 5 728 (3 320, 11 435) | 4 827 (1 324, 9 831) | 0.546 |
| ALT (0-40 U/L) | 96 (51, 208) | 120 (55, 221) | 93 (51, 209) | 92 (38, 154) | 0.500 |
| AST (0-40 U/L) | 62 (36, 127) | 83 (37, 151) | 64 (36, 124) | 54 (29, 114) | 0.306 |
| LDH (100-250 IU/L) | 522 (317, 770) | 587 (339, 783) | 569 (330, 836) | 387 (258, 615) | 0.113 |
| CK (26-200 IU/L) | 2 157 (810, 4 645) | 1 753 (771, 4 241) | 2 157 (861, 5 481) | 2 326 (612, 4 709) | 0.956 |
| CRP (<8 mg/L) | 2.9 (1.9, 5.5) | 2.9 (1.9, 5.2) | 4.3 (2.2, 8.6) | 2.6 (1.6, 5.2) | 0.198 |
| ESR (<20 mm/h) | 8 (4, 16) | 9 (4, 20) | 8 (4, 20) | 6 (3, 13) | 0.466 |
| Fet (11.0-306.8 μg/L) | 123.0 (48.9, 231.1) | 120.0 (58.9, 218.2) | 172.0 (109.9, 716.7) | 86.0 (22.0, 205.0) | 0.126 |
| IgG (6.94-16.20 g/L) | 10.50 (8.28, 14.13) | 11.60 (8.73, 15.65) | 8.59 (6.03, 11.28) | 10.50 (8.87, 13.40) | 0.033# |
| IgA (0.68-3.78 g/L) | 1.67 (1.17, 2.35) | 1.86 (1.35, 2.58) | 1.32 (1.03, 1.92) | 1.56 (0.09, 2.54) | 0.105 |
| IgM (0.60-2.63 g/L) | 1.12 (0.79, 1.45) | 1.19 (0.82, 1.76) | 0.88 (0.66, 1.21) | 1.18 (0.84, 1.42) | 0.109 |
| C3 (0.70-1.28 g/L) | 0.86 (0.75, 1.01) | 0.87 (0.77, 0.99) | 0.88 (0.78, 1.05) | 0.82 (0.71, 1.03) | 0.336 |
| C4 (0.16-0.47 g/L) | 0.18 (0.15, 0.22) | 0.19 (0.15, 0.23) | 0.20 (0.17, 0.24) | 0.17 (0.12, 0.20) | 0.067 |
| T cell (1 000-3 000 cell/mL) | 2 060 (1 555, 2 650) | 1 870 (1 480, 2 240) | 1 990 (1 370, 2 350) | 2 620 (1 570, 3 350) | 0.027△ |
| CD3+ T cell (808-2 072 cell/mL) | 1 500 (1 038, 1 877) | 1 400 (999, 1 686) | 1 458 (903, 1 978) | 1 767 (1 125, 2 378) | 0.760 |
| CD4+ T cell (380-1 280 cell/mL) | 853 (608, 1 283) | 817 (604, 1 114) | 758 (456, 1 123) | 1 767 (1 125, 2 378) | 0.042 |
| CD8+ T cell (229-982 cell/μL) | 493 (375, 761) | 477 (378, 678) | 653 (345, 797) | 554 (348, 812) | 0.586 |
2.3. 各组IMNM患者的肌肉病理特征
3组IMNM患者肌肉活检病理特征显示,各组在肌细胞坏死、再生和吞噬,肌细胞膜MHC-Ⅰ分子表达上调和肌内膜结缔组织增生等病理特征上均无差异。IMNM患者肌组织中炎症细胞浸润肌内膜多见,而血管周围浸润相对少见,CD4+T细胞(81.7%)和CD68+巨噬细胞(79.8%)是IMNM肌组织中浸润的主要炎症细胞,CD8+T细胞(54.8%)和CD20+B细胞(6.7%)较少见。其中,MSAs阴性组肌内膜的CD4+T细胞和CD68+巨噬细胞的浸润均较抗SRP和抗HMGCR组多见(分别为88.2% vs. 57.4%和60.9%, χ2=9.373,P=0.009;91.2% vs. 59.1%和38.1%, χ2=17.736,P<0.001)。MSAs阴性组MAC的表达较抗SRP和抗HMGCR组多, 3组间差异有统计学意义(94.1% vs. 77.3%和52.4%, χ2=13.095,P=0.015,表3、图1)。
3.
IMNM不同抗体组间肌肉病理特征比较
Comparisons of pathological features of different serological subgroups of IMNM
| Features | IMNM (n=104) | Anti-SRP (n=47) | Anti-HMGCR (n=23) | MSAs negative (n=34) | P |
| MHC-Ⅰ, major histocompatibility complex class Ⅰ; MAC, membrane attack complex; other abbreviations as in Table 1. Date are shown as n(%). *P<0.017, between anti-SRP /anti-HMGCR group and MSAs negative group; # P<0.017, between anti-SRP and MSAs negative group; △ P<0.017, between anti-HMGCR and MSAs group. | |||||
| Muscle fibre | |||||
| Necrosis | 98 (94.2) | 43 (91.5) | 21 (91.3) | 34 (100.0) | 0.213 |
| Regeneration | 70 (67.3) | 33 (70.2) | 11 (47.8) | 26 (76.5) | 0.066 |
| Phagocytosis | 68 (65.4) | 27 (57.4) | 14 (60.9) | 27 (79.4) | 0.107 |
| Connective tissue proliferation | 36 (34.6) | 17 (36.2) | 8 (34.8) | 11 (32.4) | 0.938 |
| MHC-Ⅰ expression on sarcolemma | 82 (78.8) | 35 (74.5) | 17(73.9) | 30 (88.2) | 0.263 |
| Partial expression | 56 (53.8) | 24 (51.1) | 11 (47.8) | 21 (61.8) | 0.512 |
| Diffuse expression | 26 (25.0) | 11 (23.4) | 6 (26.1) | 9 (26.5) | 0.953 |
| Inflammation infiltration | |||||
| CD4+T cell | 85 (81.7) | 35 (74.5) | 18 (78.3) | 32 (94.1) | 0.045 |
| Endomysial | 71 (68.3) | 27 (57.4) | 14 (60.9) | 30 (88.2) | 0.009* |
| Perivascular | 30 (28.8) | 17 (36.2) | 6 (26.1) | 7 (20.6) | 0.295 |
| CD8+T cell | 57 (54.8) | 21 (44.7) | 11 (47.8) | 25 (73.5) | 0.027# |
| Endomysial | 48 (46.2) | 17 (36.2) | 8 (34.8) | 23 (67.6) | 0.009* |
| Perivascular | 17 (16.3) | 8 (17.0) | 4 (17.4) | 5 (14.7) | 0.951 |
| CD20+B cell | 7 (6.7) | 2 (4.3) | 1 (4.3) | 4 (11.8) | 0.361 |
| Endomysial | 4 (3.8) | 1 (2.1) | 0 | 3 (8.8) | 0.168 |
| Perivascular | 3 (2.9) | 1(2.1) | 1 (4.3) | 1 (2.9) | 0.124 |
| CD68+ macrophage | 79/99 (79.8) | 35/44 (79.5) | 11/21 (52.4) | 32 (94.1) | 0.002△ |
| Endomysial | 65/99 (65.7) | 26/44 (59.1) | 8/21 (38.1) | 31 (91.2) | <0.001* |
| Perivascular | 24/99 (24.2) | 18/44 (40.9) | 3/21 (15.0) | 3 (8.8) | 0.003# |
| MAC | 77/99 (77.8) | 34/44 (77.3) | 11/21 (52.4) | 32 (94.1) | 0.001△ |
| Sarcolemma | 55/99 (55.6) | 20/44 (45.5) | 9/21 (42.9) | 26 (76.5) | 0.015* |
| Sarcoplasm | 18/99 (18.2) | 8/44 (18.2) | 3/21 (14.3) | 7 (20.6) | 0.841 |
| Capillaries | 31/99 (31.3) | 19/44 (43.2) | 4/21 (19.0) | 8 (23.5) | 0.070 |
1.
IMNM肌肉病理特征
The pathological features of IMNM
The expression of MHC-Ⅰ on sarcolemma (B, F, J); the endomysial infiltration of CD68 (C, G); the perivascular infiltration of CD4 (K); the deposition of membrane attack complex (MAC) in muscle fiber (D) or sarcolemma (H); CD8 surrounding non-necrotic muscle fiber (L). A, E, I, scattered necrotic muscle fibres in HE staining; B-D, F-H, J-L, immunohistochemistry staining.
3. 讨论
临床长期以来对IIM的诊断沿用的是1975年Bohan和Peter的诊断标准[5,6],将IIM分为PM和DM两个临床亚型。1991年美国学者Dalakas[11]提出PM病理特征为CD8+T细胞浸入和包绕表达MHC-Ⅰ分子上调的未坏死的肌细胞,而DM的病理特征为束周萎缩。但在临床工作中,IIM的肌肉活检病理检测中经常见不到上述典型的PM和DM病理特征,为满足临床诊断需求,2004年ENMC提出应将IMNM作为IIM的一个特殊的临床亚型来独立诊断[1]。该亚型将IMNM定义为临床表现有肌酶升高和肌无力,肌肉病理特征表现为肌组织中仅见肌细胞坏死,而少或无炎症细胞浸润[1,2,3]。
近年来,随着对MSAs研究的深入,越来越多的报道显示抗SRP抗体和抗HMGCR抗体阳性的患者临床以显著肌酶升高和肌无力为主要表现,而无或少皮疹[12,13,14,15,16],肌肉组织病理特征表现为2004年ENMC定义的IMNM的病理特征。因此,有学者提出抗SRP抗体和抗HMGCR抗体可以作为IMNM的血清标记物,用于帮助诊断IMNM。但临床上仍可见到部分患者的病理和临床特征符合上述2004年ENMC关于IMNM的诊断标准,而血清中却检测不到任何肌炎特异性自身抗体。对于血清阴性的IMNM与抗SRP抗体和抗HMGCR抗体阳性的IMNM是否存在不同, 3组IMNM之间在临床、实验室、病理特征上有无差异,目前尚未见系统研究。
本研究中所有IMNM患者以肌无力和CK升高为主要临床表现。既往研究显示,抗SRP抗体阳性的IMNM患者肌肉症状更重,更易出现严重肌无力、肌萎缩、吞咽困难和CK水平显著升高[12],但本研究显示抗SRP抗体和抗HMGCR抗体阳性以及MSAs阴性的3组患者之间,肌无力和CK升高的严重程度差异并无统计学意义,而抗HMGCR阳性组CK中位数高于MSAs阴性组和抗SRP阳性组。以往研究发现,仅4%~6%的IMNM患者可出现皮疹,如Gottron征、向阳疹等[1-3,11],但本研究提示皮疹并不是IMNM的少见临床特征,26%的IMNM患者在病程中可出现各种类型的皮疹,其中抗HMGCR抗体阳性的患者皮疹最常见(34.8%),且以V形疹多见(表1),与既往的报道不完全一致[4]。
有研究表明,IMNM患者合并ILD较少见,仅有1/5的抗SRP抗体阳性的IMNM患者合并ILD[3],而本研究中有46.5%的IMNM合并有经高分辨率CT证实的ILD,高达64.4%的抗SRP抗体阳性的IMNM合并ILD,与既往的研究不同。进一步研究发现,尽管超过一半的抗SRP抗体阳性的IMNM患者合并ILD,但是肺间质病变的程度均较轻,多无咳嗽、气短、呼吸困难等临床症状,为无症状性ILD,不影响生存(表1)。此外,近60%的MSAs阴性患者血清中可检测到滴度不等的ANA(表2),提示这部分患者体内可能存在潜在的未知抗体。
尽管2004年ENMC标准对IMNM的病理特征进行了定义,但肌细胞坏死、少或无炎症浸润并不是IMNM特异性的病理改变,在其他可引起肌细胞坏死的疾病,如肌营养不良、代谢性肌病等也可见到上述特征[17]。免疫组织化学染色检测MHC-Ⅰ类分子和炎性细胞在肌组织中的表达将有助于区分IMNM和其他肌病。本研究显示,所有IMNM患者的肌组织均有不同程度的肌细胞坏死,但炎症浸润的特点在各组IMNM中不尽相同。抗SRP抗体和抗HMGCR抗体阳性的患者肌组织中浸润的炎症细胞以CD68+巨噬细胞为主,且主要浸润肌内膜,与以往研究[18,19]结果相似。MSAs阴性组的患者,肌组织浸润的炎性细胞除CD68+巨噬细胞外,尚有较多CD4+和CD8+T细胞,且在肌内膜和血管周围均有表达,这与2004年ENMC定义的IMNM病理特征并不完全一致,提示现有的IMNM诊断标准仍有待进一步补充和完善。
综上所述,IMNM是IIM的一个特殊临床亚型,其血清特点包括抗SRP抗体阳性、抗HMGCR抗体阳性和MSAs阴性三种类型。三组IMNM中抗HMGCR抗体阳性的患者皮疹的发生率更高;而抗SRP抗体阳性的患者合并ILD的比例高;MSAs阴性患者更易伴随其他结缔组织病出现,肌组织中浸润的炎性细胞的类型更多,分布更广泛。IMNM无论是在临床、血清学,还是肌肉病理特征上均存在异质性,在这类患者中开展自身抗体检测和肌肉病理检测对进一步认识IMNM的发病机制,从而制定针对不同的IMNM亚型的治疗策略有重要意义。
Funding Statement
北京市科学技术委员会首都临床特色应用（Z171100001017208）
Supported by Beijing Municipal Science and Technology Commission(Z171100001017208)
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