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目的:探讨组织蛋白酶K(cathepsin K,Cat K)在高血压性心脏病心室重塑发生发展中的表达及其活性与心肌纤维化的关系。方法:7周龄雄性Dahl盐敏感(DS)大鼠分别给予高负荷食盐(8%)或正常负荷食盐(0.3%)19周,建立高血压性心脏病心衰(H-HF)模型和对照组(19W-C)。另设人心肌活检标本作研究对象(H-HF患者10例和对照组6例)。用RT-PCR和免疫组化分别检测Cat K mRNA及蛋白表达,酶谱法测定大鼠心肌组织中的组织蛋白酶活性,心脏石蜡切片Azan染色法分析左心室肌间质和血管周围纤维化程度,细胞荧光染色法分析白介素-β1(IL-β1)对培养心肌细胞的Cat K的表达及其胶原蛋白分解能的影响。结果:H-HF组大鼠和患者心肌中的Cat K mRNA的表达显著高于19W-C组和对照组人(P<0.01)。免疫组化法和in situ法分析显示增高的Cat K mRNA和蛋白主要表达于心肌细胞。H-HF组大鼠心肌组织蛋白酶依赖性胶原蛋白分解能显著高于19W-C组。H-HF组大鼠心肌中IL-β1表达也在显著增高。IL-β1刺激心肌细胞的Cat K蛋白及其胶原蛋白分解活性。心肌中的Cat K mRNA表达与左心室肌纤维化面积呈显著正相关(r=0.68,P<0.01)。结论:在心肌中Cat K表达及分泌受IL-β1的调控,并参与高血压性心脏病的发生、发展过程,提示心肌Cat K在H-HF的心肌重塑及纤维化发展中起重要作用。
Objective: To investigate the expression and activity of cathepsin K (Cat K) in the development and progression of ventricular remodeling in hypertensive heart disease and its relationship with myocardial fibrosis. Methods: Hypertensive heart failure (H-HF) model and control were established in 7-week-old male Dahl salt sensitive (DS) rats with high-load salt (8%) or normal-load salt (0.3% Group (19W-C). Another myocardial biopsy specimens for the study (H-HF patients 10 cases and control group 6 cases). The expression of Cat K mRNA and protein were detected by RT-PCR and immunohistochemistry respectively. The activity of cathepsin in myocardial tissue was determined by zymography. Azan staining was used to analyze the interstitial and perivascular fibrosis. Effect of Interleukin-β1 (IL-β1) on Cat K Expression and Collagen Decomposition Energy in Cultured Cardiomyocytes by Fluorescent Staining. Results: The expression of Cat K mRNA in H-HF group was significantly higher than that in 19W-C group and control group (P <0.01). Immunohistochemistry and in situ analysis showed that elevated Cat K mRNA and protein were mainly expressed in cardiomyocytes. H-HF group myocardial tissue protease-dependent collagen degradation was significantly higher than the 19W-C group. The level of IL-β1 in H-HF group was also significantly increased. IL-β1 stimulates Cat K protein and its collagenolytic activity in cardiomyocytes. There was a significant positive correlation between Cat K mRNA expression in myocardium and left ventricular myofiber area (r = 0.68, P <0.01). CONCLUSION: The expression and secretion of Cat K in myocardium are regulated by IL-β1 and involved in the development and progression of hypertensive heart disease, suggesting that Cat K plays an important role in myocardial remodeling and fibrosis development of H-HF .