病毒性心肌炎与扩张型心肌病血清抗M受体抗体研究

A study of anti muscarinic receptor antibodies in sera from patients with viral myocarditis and dilated cardiomyopathy

目的Ｍ受体和肾上腺素能受体通过自主神经调节心脏功能。在某些病理条件下，血清抗Ｍ受体抗体的产生与疾病的发生、发展密切相关。本研究拟通过对病毒性心肌炎（ＶＭＣ）与扩张型心肌病（ＤＣＭ）患者血清抗Ｍ受体抗体的检测，探讨该指标的辅助判断价值。方法随机选择ＶＭＣ患者３２例、ＤＣＭ患者１２例、冠心病患者２０例及正常对照组１４例，受试者血清与人心室肌组织片预孵育后，冷冻切片法测定Ｍ受体与配基［３Ｈ］ＱＮＢ结合的Ｂｍａｘ与Ｋｄ值。ＶＭＣ患者血清同时进行心肌肌钙蛋白Ⅰ（ｃＴｎⅠ）测定与淋巴细胞肠道病毒逆转录扩增。结果７例正常人（意外死亡者）心室肌Ｍ受体与配基［３Ｈ］ＱＮＢ结合的Ｂｍａｘ值为５１．４±６．０ｆｍｏｌ／Ｌｍｇｐｒ，Ｋｄ值为０．６８±０．０９ｎｍｏｌ／Ｌ。ＤＣＭ患者血清孵育后Ｍ受体和配基结合的Ｂｍａｘ值下降（Ｐ＜０．０１），Ｋｄ值升高（Ｐ＜０．０１）；ＶＭＣ患者仅Ｋｄ值升高（Ｐ＜０．０１），但ｃＴｎＩ阳性及病毒扩增阳性者Ｂｍａｘ值同时下降（Ｐ＜０．０５）。结论ＶＭＣ和ＤＣＭ患者血清中存在抗Ｍ受体抗体，其导致心肌Ｍ受体和配基结合的数目与亲和力改变，对ＤＣＭ诊断以及ＶＭＣ向ＤＣＭ演变可能提供有益的证据。

Objective Muscarinic receptor (MR) and adrenergic receptors in human heart play an important role in maintaining physiologic function. In some clinical cases, the level of serum anti MR antibodies was reported to be related to the pathogenesis and progress of diseases. This work was designed to investigate the concentration of anti MR autoantibodies in sera from patients of viral myocarditis (VMC) and dilated cardiomyopathy (DCM) and evaluate the significance as a diagnostic marker. Methods Thirty two patients with VMC, 12 DCM, 20 coronary heart disease (CHD) (total 64 cases) and 14 normals were enrolled and blood samples were collected. The level of autoantibodies in sera was determined by inhibition of 3H QNB binding on incubation left ventricular slide with the patients′ sera. Serum cardiac troponin I (cTnI), a specific marker reflecting cardium injury was assayed as well enterovirus RNA was detected by RT PCR. Results The value B max and Kd of MR on ventricule of seven normal subjects were 51.4±6.0 fmol/mg·pro and 0.68±0.09 nmol/L, respectively. After preincubation with sera from patients of DCM, the B max of MR decreased, while Kd value increased ( P < 0.01). Sera of VMC patients only caused increase of Kd, however, sera from VCM patients with positive cTnI and enterovirus RNA behaved similarly as those of DCM patients. Conclusion The present data demonstrate that anti MR autoantibodies which inhibited B max and affinity of cardiac MR appeared in sera from patients of DCM and VMC. The presence of anti MR autoantibodies might give an evidence for evaluation the progress of VMC leading to DCM and the diagnosis of DCM.