黏病毒抗性蛋白A在皮肌炎病理诊断中的应用

MxA Is A Useful Pathological Biomarker in the Diagnosis of Dermatomyositis

目的旨在了解黏病毒抗性蛋白A(MxA)在不同炎性肌病肌纤维中的表达情况,探讨MxA在皮肌炎病理诊断中的应用价值。方法本研究采用回顾性研究方法。收集2013至2017年所做的炎性肌病肌活检标本和临床资料,其中皮肌炎18例为皮肌炎组,其他炎性肌病22例(免疫介导坏死性肌病7例,包涵体肌炎6例,抗合成酶抗体综合征5例,重叠性肌炎4例)为对照组。采用免疫组化学法评估MxA在不同炎性肌病肌纤维中的表达情况,并与皮肌炎病理特征(1)束周萎缩;(2)主要组织相容性复合体-Ⅰ(MHC-Ⅰ)束周表达上调;(3)毛细血管膜攻击复合物(C5b-9)沉积进行比较。结果皮肌炎组15例患者的肌纤维MxA表达上调,以束周肌纤维上调最为明显;对照组未见表达上调。MxA对皮肌炎诊断的敏感度和特异度分别为83%和100%,束周萎缩的敏感度和特异度分别为72%和95%。MHC-Ⅰ束周表达上调的敏感度和特异度分别为50%和86%。毛细血管C5b-9沉积的敏感度和特异度分别为39%和81%。将束周萎缩或MxA阳性(合集)作为一个指标,其敏感度和特异度分别高达94%和100%。结论 MxA对皮肌炎诊断的敏感度和特异度较经典的皮肌炎病理标志束周萎缩更高,也优于MHC-Ⅰ的束周表达上调及毛细血管C5b-9沉积。MxA染色对炎性肌病的诊断和鉴别诊断具有较高的参考价值。

Aim To evaluate the diagnostic utility of myxovirus resistance protein A( MxA) in dermatomyositis( DM),the expression of MxA in muscle biopsies from DM patients and patients with other inflammatory myopathies. Methods Muscle biopsies from 18 DM patients( DM group) and 22 patients with other inflammatory myopathies( 7 with immune-mediated necrotizing myopathy,6 with inclusion body myopathy,5 with anti-synthetase syndrome and 4 with overlap myositis)( the control group) during 2013-2017 in our hospital were collected. MxA expression was detected by immunohistochemistry on muscle specimens and compared with other pathologic hallmarks of DM: perifascicular atrophy( PFA),perifascicular major histocompatibility complex-class Ⅰ( MHC-Ⅰ) upregulation and C5 b-9 deposition on capillaries. Results MxA expression was observed in 15 patients in DM group but in none of the control group. The expression was more prominent in the perifascicular area. The sensitivity of MxA for DM diagnosis was 83%. The sensitivity of PFA,perifascicular MHC-Ⅰ upregulation and capillary C5 b-9 deposition was 72%,50% and 39%,respectively. The specificity of MxA for DM diagnosis was 100%,while the specificity of PFA,perifascicular MHC-I upregulation and capillary C5 b-9 deposition was 95%,86% and 81%,respectively. The diagnostic sensitivity and specificity reaches 94% and 100% if either PFA or MxA is considered as diagnostic hallmark of DM. Conclusion The diagnostic sensitivity and specificity of sarcoplasmic Mx A expression by immunohistochemistry for DM are higher than PFA,perifascicular MHC-Ⅰupregulation or capillary C5 b-9 deposition,indicating its utility in the diagnosis of DM.