新型11βHSD2特异性抑制剂治疗心肌纤维化的作用及机制

Myocardial fibrosis becomes an important pathological feature of Heart failure. Aldosterone classically plays a role in promoting transepithelial transport of sodium to regulate blood volume and blood pressure. But during pathological process, aldosterone binds to mineralocorticoid receptor to induce myocardial fibrosis due to the overexpression of 11β hydroxysteroid dehydrogenase 2 (11βHSD2), which inactivates active cortisol into biologically inert cortisone. In normal myocardial cells which has no/or lower 11βHSD2, cortisol always binds to the mineralocorticoid receptor, forming receptor complex, which has no transcription factor, thus against aldosterone action. However, when 11βHSD2 is overexpressed, this cortisol is metabolized and only aldosterone binds to mineralocorticoid receptor to cause myocardial fibrosis. Therefore, the discovery of a specific 11βHSD2 inhibitor to treat myocardial fibrosis is very important and is the goal of this project. WZ51 is a synthetic chemical which specially inhibits 11βHSD2. Therefore, as a lead compound, we will synthesize more than 20 WZ51 derivatives，screen the specific inhibition of 11βHSD2, and evaluate them by pharmacokinetics and toxicity tests. We will use myocardial fibrosis rat model to evaluate the potency of WZ51 in vivo, and explore the mechanism (including the MAPK pathway) of WZ51 using in vitro 11βHSD2 overexpressed cardiac fibroblast isolated from neonatal rats. The blockade of aldosterone will provide additional therapeutic benefit using an 11βHSD2 specific inhibitor in the treatment of heart failure.

心肌纤维化成为心脏功能衰竭的一个重要病理特征。醛固酮可经过上皮细胞促进钠的重吸收，从而调节血容量和血压。但病理时，醛固酮激活心肌盐皮质受体（MR），可能与心肌成纤维细胞过表达11β羟基类固醇脱氢酶2（11βHSD2）有关。该酶可转化皮质醇成无活性的可的松，皮质醇在心肌与MR结合成复合物但不产生心肌盐皮质受体样作用，可拮抗醛固酮激活MR。因此，研究新型11βHSD2特异性抑制剂治疗心肌纤维化是本项目的目标。从合成的WZ51衍生物筛选出新型11βHSD2特异性抑制剂，测定其药代动力学和毒性，并采用去氧皮质酮（醛固酮前体）造成大鼠心肌纤维化模型和11βHSD2过表达小鼠模型来评估WZ51的药理作用。此外分离乳鼠心肌成纤维细胞，并使其过表达11βHSD2，在体外验证WZ51的抗心肌纤维化作用和机制（包括MAPK通路），为心肌纤维化疾病的药物治疗提供新的思路和实验依据。

心肌纤维化成为心脏功能衰竭的一个重要病理特征。醛固酮可经过上皮细胞促进钠的重吸收，从而调节血容量和血压。但病理时，醛固酮激活心肌盐皮质受体(MR)，可能与心肌成纤维细胞过表达11β羟基类固醇脱氢酶2(11βHSD2)有关。该酶可转化皮质醇成无活性的可的松，皮质醇在心肌与MR结合成复合物但不产生心肌盐皮质受体样作用，可拮抗醛固酮激活MR。 因此，研究新型11βHSD2特异性抑制剂治疗心肌纤维化是本项目的目标。我们采用去氧皮质酮(醛固酮前体)造成大鼠心肌纤维化模型，用CK-MB试剂盒和LDH试剂盒检查肌酐和血清乳酸脱氢酶；大鼠心脏组织通过HE染色和Masson染色来观察组织形态和胶原沉积情况；免疫组化法(IHC)观察结缔组织生长因子(CTGF)和11βHSD2的表达；此外分离H9C2大鼠细胞，通过免疫印迹法(western blot)研究CTGF、11βHSD2的表达程度与醛固酮刺激的联系，以及WZ51对醛固酮和皮质酮刺激的干预作用。最终明确了:1) 去氧皮质酮可以诱导大鼠MF的形成，加用螺内酯可以显著减少MF的发生;2)外源性醛固酮显著增强了大鼠心肌组织中CTGF的表达;3）姜黄素衍生物WZ51具有抗醛固酮诱导的大鼠MF作用;4）WZ51抗纤维化作用的机制可能与其对11βHSD2酶活性的选择性抑制，增加心肌中皮质醇水平来竞争盐皮质激素受体MR，拮抗醛固酮与MR的结合，最终缓解MF的发展。为心肌纤维化疾病的药物治疗提供新的思路和实验依据。