小鼠自身免疫性心肌炎发病过程中4-1BB/4-1BBL和IL-15的表达及意义

目的： 探讨在小鼠自身免疫性心肌炎发病过程中4-1BB/4-1BBL、IL-15的表达和变化，及其免疫学活性对心肌炎的影响。方法：将提纯的猪心肌肌球蛋白和完全弗氏佐剂等体积混合成乳浊液在1 d、8 d及30 d免疫具有遗传易感性的BALB/c小鼠，建立实验性自身免疫性心肌炎（EAM）模型。对照组小鼠仅用完全弗氏佐剂皮下注射。分别于初次免疫后21 d、80 d进行心肌炎症评分及血清肌钙蛋白I(cTnI)测定，免疫组化检测心肌淋巴细胞活化诱导受体配体（4-1BBL）的表达，ELISA法检测血清白细胞介素-15(IL-15)的浓度，RT-PCR技术检测4-1BB/4-1BBL和IL-15 mRNA在小鼠心肌组织中的表达。结果：在急性期21 d，EAM组小鼠心肌组织见不同程度的炎性细胞浸润和心肌细胞变性坏死、血清cTnI水平升高（P<0.05）；80 d EAM组小鼠心肌组织炎症减弱伴有纤维化出现、cTnI较前期降低；心肌4-1BBL和血清IL-15在EAM组中表达明显，在对照组中少量表达（P<0.05）；21 d EAM组小鼠心肌组织中4-1BB/4-1BBL和IL-15基因表达水平均高于对照组(P<0.01)，且与心肌炎症呈明显的正相关，80 d时表达仍然升高(P<0.05)。结论：4-1BB/4-1BBL和IL-15在EAM小鼠发病过程中的表达上调，4-1BB/4-1BBL共刺激通路和IL-15可能协同参与了自身免疫性心肌炎的发生发展过程。

Expression and significance of 4-1BB/4-1BBL and IL-15 in the experimental autoimmune myocarditis

AIM: To establish the animal model of experimental autoimmune myocarditis (EAM) in BALB/c mice and to investigate the expression and significance of 4-1BB/4-1BBL and IL-15 in mouse EAM. METHODS: Cardiac myosin was extracted from porcine ventricular myocardium. Genetically predisposed BALB/c mice were immunized with cardiac myosin covered by complete freunds adjuvant (CFA) on 1 d, 8 d and 30 d. The control mice were immunized with CFA only. On 21 d and 80 d after the first immunization, the areas of inflammation were identified by HE staining and cTnI was examined. Then 4-1BBL and IL-15 were determined by immunohistochemistry and ELISA, respectively. The mRNA levels of 4-1BB/4-1BBL and IL-15 were measured by semi-quantitative RT-PCR. RESULTS: In experimental group, histopathological examination of cardiac tissue showed an obvious inflammatory cell infiltration with myocyte necrosis at 21 d, the cTnI was higher than that in control group. On 80 d, fibrosis and a few inflammatory cells were observed. The cTnI in EAM group was still higher than that in control group (P<0.05). No inflammation and fibrosis were emerged in the myocardium of control mice. In addition, as compared with control groups, immunohistochemistry and mRNA abundance for both 4-1BB/4-1BBL and IL-15 were up-regulated at acute phase of the EAM model (P<0.01). On 80 d, the mRNA abundance was still up-regulated (P<0.05).CONCLUSION: The expressions of 4-1BB/4-1BBL and IL-15 in myocardium are up-regulated in experimental autoimmune myocarditis. The 4-1BB/4-1BBL costimulating pathway and IL-15 may play a role in the occurrence and development of autoimmune myocardtis.