Zhou Zi-hua, Liao Yu-hua, Li Liu-dong, Wang Bin, Wei Fen, Wang Min, Wei Yu-miao
Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430022, China.
Zhonghua Yi Xue Za Zhi. 2005 Mar 9;85(9):625-9.
To study the effects of autoantibodies against alpha1-adrenergic receptor on the cardiac remodeling and relevant mechanism.
Four-week-old male Wistar rats were immunized with synthesized second extracellular loop of alpha1-adrenergic receptor and raised for one year, with spontaneously hyperetensive rats (SHRs) and no-immunized Wistar rats of the same age as controls. Every one or two months blood was collected from the caudal vein to detect the level of serum antibodies to alpha1-adrenergic receptor by ELISA and the systolic blood pressure (SBP) and heart rate were measured. One year after the rats were killed and their hearts were taken out. The heart weight/body weight ratio, cardiac muscle cell cross-sectional area (CSA), interstitial collagen volume fraction (CVF) and the ratio of perivascular collagen area to vessel luminal area (PVCA) were calculated, the expression of alpha1-adrenergic receptor, c-fos and c-Jun in heart were measured by RT-PCR, Western blotting and immunohistochemistry.
During the experiment the blood pressure of the SHRs were significantly higher than those of the immunization group and normal control group (both P < 0.01) without significant difference between the 2 latter groups. The heart weight/body weight ratio, CSA, CVF and PVCA of the immobilization group were 3.32 mg/g +/- 0.25 mg/g, 231 microm(2) +/- 11 microm(2), 5.40% +/- 0.66% and 1.89 +/- 0.62 respectively, all significantly higher than those of the normal control group (3.06 mg/g +/- 0.25 mg/g, 197 microm(2) +/- 19 microm(2), 3.22% +/- 0.15% and 0.86 +/- 0.17 respectively), but still significantly lower than those of the SHR group. Since the second week after immunization, the titre of antibody against of the immunization group began increase, peaked in the second and third months, and then decreased slowly, and remained at a high level by the end of experiment. The titre of antibody was not correlated with blood pressure. Hypertrophy of cardiac muscle cells and increase of sedimentation of collagen in stroma were seen in the hearts of the immunization group. RT-PCR showed that the expression of alpha1D-adrenergic receptor mRNA of the immunization group was 0.55 +/- 0.01, significantly lower than that of the normal control group (0.88 +/- 0.08, P < 0.05); the expression of c-jun mRNA in the immunization group was 0.82 +/- 0.02, significantly higher than that in the normal control group (0.42 +/- 0.07, P < 0.05); and there were no significant differences in the expressions of heart alpha1A- and alpha1B-afrenergic receptors and c-fos mRNAs between these 2 groups. Western blotting showed that the expression of c-jun protein in the immunization group was 6.24 +/- 2.13, significantly higher than that in the normal control group (2.55 +/- 0.58, P < 0.05); and there were no significant differences in the expressions of c-fos andalpha1A-adrenergic receptor proteins between these 2 groups.
The antibodies against alpha1-adrenergic receptor up-regulates the expression of c-jun in cardiac muscle cells and interstitial fibroblast, which may be an immunologic mechanism of cardiac remodeling.
研究抗α1-肾上腺素能受体自身抗体对心脏重塑的影响及其相关机制。
用合成的α1-肾上腺素能受体第二细胞外环免疫4周龄雄性Wistar大鼠，饲养1年，以自发性高血压大鼠（SHRs）和同年龄未免疫的Wistar大鼠作为对照。每隔1或2个月从尾静脉采血，用ELISA法检测血清抗α1-肾上腺素能受体抗体水平，测量收缩压（SBP）和心率。大鼠处死后取出心脏，计算心脏重量/体重比值、心肌细胞横截面积（CSA）、间质胶原容积分数（CVF）以及血管周围胶原面积与血管腔面积之比（PVCA），用RT-PCR、蛋白质印迹法和免疫组织化学法检测心脏中α1-肾上腺素能受体、c-fos和c-Jun的表达。
实验期间，SHRs的血压显著高于免疫组和正常对照组（均P<0.01），后两组之间无显著差异。免疫组的心脏重量/体重比值、CSA、CVF和PVCA分别为3.32mg/g±0.25mg/g、231μm²±11μm²、5.40%±0.66%和1.89±0.62，均显著高于正常对照组（分别为3.06mg/g±0.25mg/g、197μm²±19μm²、3.22%±0.15%和0.86±0.17），但仍显著低于SHR组。自免疫后第2周起，免疫组抗α1-肾上腺素能受体抗体滴度开始升高，在第2和第3个月达到峰值，然后缓慢下降，实验结束时仍维持在较高水平。抗体滴度与血压无关。免疫组心脏可见心肌细胞肥大和间质胶原沉积增加。RT-PCR显示，免疫组α1D-肾上腺素能受体mRNA表达为0.55±0.01，显著低于正常对照组（0.88±0.08，P<0.05）；免疫组c-jun mRNA表达为0.82±0.02，显著高于正常对照组（0.42±0.07，P<0.05）；两组心脏α1A-和α1B-肾上腺素能受体及c-fos mRNA表达无显著差异。蛋白质印迹法显示，免疫组c-jun蛋白表达为6.24±2.13，显著高于正常对照组（2.55±0.58，P<0.05）；两组c-fos和α1A-肾上腺素能受体蛋白表达无显著差异。
抗α1-肾上腺素能受体抗体上调心肌细胞和间质成纤维细胞中c-jun的表达，这可能是心脏重塑的一种免疫机制。
