肺动脉高压及高肺血流对肺小动脉壁弹性蛋白离解与原弹性蛋白mRNA表达的影响

Effects of the pulmonary hypertension and high lung blood flow on elastolysis and the expression and distribution of tropoelastin mRNA in pulmonary arteriole walls

目的 研究肺动脉压力及肺血流量对肺小动脉壁弹性蛋白离解与原弹性蛋白mRNA表达的影响 ,以帮助阐明先天性心脏病 (简称先心病 )肺动脉高压 (简称肺高压 )肺血管重建的机制。方法 将患儿 15例分为对照组 (组 1) 4例、先心病高肺血流组 (组 2 ) 4例及先心病肺高压组 (组 3) 7例。弹性蛋白离解用透射电镜定性分析、计算机图像分析系统定量分析 ;弹性蛋白的表达分布用免疫组织化学方法、原位杂交方法。结果 与组 1相比 ,组 2和组 3肺小动脉内弹力层厚度均明显减少 (P均 <0 .0 1) ,而组 2与组 3间差异无显著性 (P =0 .16 )。应用相关分析表明 ,肺小动脉内弹力层厚度与肺血流量呈负相关 (r=- 0 .81,P <0 .0 1) ,与肺动脉压力无相关性 (r=0 .30 ,P =0 .18)。电镜观察 :组1各例内弹力层完整均匀 ;组 2有不同程度内弹力层变薄、碎裂现象 ;组 3中有 2例内弹力层消失 ,内膜与肌层直接接触 ,有 4例可见不同程度内弹力层变薄碎裂。原位杂交 :组 1、组 2均未见阳性信号表达 ,组 3有不同程度表达 ,其阳性率与肺动脉压力呈正相关 (r=0 .89,P <0 .0 1) ,而与肺血流量无关(r=- 0 .5 9,P =0 .0 8)。表达部位主要集中于肺小动脉的外膜及其周围。免疫组织化学法 :组 1、组 2各例阳性显色主要集中于血管壁中层内、外弹力层?

Objective The effect of pulmonary artery pressure (PAP) and high lung blood flow on elastolysis and tropoelstin mRNA expression and distribution in the wall of pulmonary arterioles was investigated to clarify the pathogenesis of pulmonary vascular remodeling associated with pulmonary hypertension (PH) of congenital heart disease (CHD). Method The present study included three groups, control group of 4 cases (group 1), high lung blood flow group of 4 cases (group 2) and PH group of 7 cases (group 3). Elastolysis was analyzed qualitatively with the transmission electron microscopy and computer image analysis system. The expression and distribution of tropoelastin mRNA were detected by immunohistochemistry and in situ hybridization (ISH). Result Compared with group 1, the thickness of IEL in group 2 and group 3 both reduced ( P <0.01), while there was no difference of the IEL thickness between group 2 and group 3 ( P =0.16). The thickness of IEL was negatively correlated with the lung blood flow ( r =-0.81, P <0.01), and was not correlated with PAP ( r =0.30, P =0.18). The electron microscopy observation revealed that IEL was intact at pulmonary arteriole in all cases in group 1. In group 2, IEL was intact but thin in one case, and thin and fragmentation in another case. In group 3, IEL was intact but thin in one case, absent along with the intima contacting directly with the muscular media in two cases, and thin and fragmentation in four cases. There was no positive signal of the tropoelastin mRNA expression in the arteriolar wall by ISH in group 1 and group 2. However, in group 3, positive signals were detected. The positive rate was correlated with PAP ( r =0.89, P <0.01), but uncorrelated with Qp/Qs ( r =-0.59, P =0.08). The distribution of expressions was mainly located at the adventitia and outer regions of pulmonary arterioles. The immuno-histochemistry study revealed positive signals located at the media of pulmonary arterioles in group 1 and group 2. In group 3, positive signals were observed in the adventitia and outer regions of pulmonary arterioles. Conclusion Elastolysis increased during the period of high lung blood flow in children with left to right shunt CHD. High lung blood flow may be the important factor stimulating the increment of elastolysis. Tropoelastin mRNA re-expression and abnormal deposition were present in PH. The high tension of pulmonary vascular wall (PH) may be the main factor of increased synthesis of elastin. This is very important in the clarification of the pathogenesis of pulmonary vascular remodeling associated with PH of CHD.