Targeted inhibition of fibrosis for the prevention of heart failure

靶向抑制纤维化以预防心力衰竭

• 批准号: 9043945
• 负责人: JASON R. McCARTHY
• 金额: $ 78.61万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9043945
• 关键词: Actins; Affinity; Agonist; Binding; Biological Preservation; Blood Circulation; Calcium; Cardiac; Cardiac Myocytes; Cell Survival; Cells; Cellular Morphology; Chronic; Collagen; Collagen Type I; Cytoskeleton; Data; Deposition; Development; Disease; Dose; Echocardiography; Encapsulated; Endothelial Cells; Fibroblasts; Fibrosis; Fluorescent Probes; GTP-Binding Proteins; Genes; Health; Heart; Heart Hypertrophy; Heart failure; Immunosuppressive Agents; In Vitro; Injury; Investigation; Ligands; MAPK3 gene; MG132; Mediating; Molecular; Molecular Analysis; Monomeric GTP-Binding Proteins; Mus; Myocardial; Myocardial Infarction; Myocardium; Nodal; Pathology; Pathway interactions; Peptides; Pharmaceutical Preparations; Preparation; Prevention; Property; Protein Biosynthesis; Proteins; Proto-Oncogene Proteins c-akt; Regulation; Role; Serum Response Factor; Signal Pathway; Signal Transduction; Site; Stimulus; Stress; Technology; Therapeutic; Therapeutic Effect; Time; Tissues; Toxic effect; Transcriptional Activation; Treatment Efficacy; Up-Regulation; Ventricular Remodeling; analog; base; cell type; cohort; constriction; coronary fibrosis; design; efficacy testing; fetal; in vivo; inhibitor/antagonist; interest; macrophage; monocyte; mouse model; multicatalytic endopeptidase complex; myocardin; nanomaterials; nanoparticle; nanoparticulate; novel; particle; prevent; protective effect; response; rho; systemic toxicity; targeted delivery; transcription factor; uptake; zeta potential

 DESCRIPTION (provided by applicant): Cardiomyocytes undergo remodeling in response to pathological stimuli, causing altered cell morphology, increased protein synthesis and upregulation of fetal genes. While initially compensatory, ultimately, these changes prove maladaptive, inducing fibrosis and adverse ventricular remodeling. In response to cardiac stress and/or injury, activation of the Ras-related small G protein RhoA was previously shown to mediate deleterious in vivo pathological responses. However, more recently, RhoA has also been shown to promote cell survival and be cardio-protective after myocardial infarct (MI) injury. To determine the molecular mechanisms that underlie these opposing roles for RhoA in the myocardium, we generated mice with a cardiomyocyte-specific deletion of RhoA (RhoAfl/fl-aMHC-Cre). In response to chronic injury (transverse aortic constriction, TAC), we found that hearts from RhoAfl/fl-aMHC-Cre mice developed an accelerated dilation, with significant loss of contractile function. Despite this, and in parallel, hearts from these mice also showed significantly decreased cardiac fibrosis, with a demonstrated decrease in transcriptional activation of genes involved in the fibrotic response, including the serum response factor (SRF) and the myocardin related transcription factor (MRTF). Taken together, our data suggest that RhoA serves as a critical bi-nodal point in response to cardiac injury, whereby a component of the downstream signaling is required to preserve contractility, while the other mediates activation of maladaptive responses due to activation of profibrotic genes. Therefore, we hypothesize that targeted inhibition of downstream RhoA-mediated pro-fibrotic genes (SRF and MRTF) will not only prevent onset of fibrosis and subsequent maladaptive responses associated with MI injury, but will also allow for the preservation of the upstream cardio-protective effects n contractility exerted by RhoA parallel signaling pathways. Nanomaterials have found wide applicability in the treatment of disease, as they possess the ability to modulate the properties o drugs, including circulation times and localization to tissues of interest. Importantly, the incorporation of therapeutic moieties within targeted nanoparticles allows for their site-specific delivery, minimizing the dose required to bring about a therapeutic effect, while concomitantly decreasing systemic repercussions. Using this technology, we will investigate novel targeting ligands for the cell specific delivery of inhibitors of cardiac fibrosis following myocardial injur. Using in-vivo, ex-vivo and in-vitro analyses, we will 1) generate and fully characterize targeted nanoagents incorporating inhibitors chosen to prevent the deposition of collagen after MI; 2) examine the in vitro and in vivo binding and inhibitory efficacy of the synthesized nanoagents; and 3) longitudinally assess the therapeutic efficacy of the targeted delivery of inhibitors in murine models of MI. Importantly, we expect that the efficacy of this technology to extend beyond MI, and be applicable to more chronic conditions, such as fibrosis caused by cardiac hypertrophy and/or valvular disease.

 描述(申请人提供)：心肌细胞在病理刺激下发生重塑，导致细胞形态改变，蛋白质合成增加，胎儿基因上调。虽然最初是代偿的，但最终这些变化被证明是不适应的，导致纤维化和不利的心室重塑。在对心脏应激和/或损伤的反应中，RAS相关的小G蛋白RhoA的激活先前被证明介导了体内有害的病理反应。然而，最近，RhoA也被证明在心肌梗死(MI)损伤后可以促进细胞存活并具有心脏保护作用。为了确定在心肌中RhoA的这些相反作用背后的分子机制，我们产生了心肌细胞特异性缺失RhoA的小鼠(RhoAfl/fl-aMHC-CRE)。RhoAfl/fl-aMHC-CRE小鼠的心脏在慢性损伤(腹主动脉缩窄，TAC)时，心脏出现加速扩张，收缩功能显著丧失。尽管如此，这些小鼠的心脏也显示出显著的心脏纤维化减轻，参与纤维化反应的基因转录激活减少，包括血清反应因子(SRF)和心肌钙蛋白相关转录因子(MRTF)。综上所述，我们的数据表明，RhoA在心脏损伤的反应中是一个关键的双结点，因此需要下游信号的一个成分来维持收缩能力，而另一个信号成分则介导由于促纤维化基因的激活而激活的不良适应反应。因此，我们假设，靶向抑制下游RhoA介导的促纤维化基因(SRF和MRTF)不仅可以防止纤维化的发生和随后与MI损伤相关的不良适应反应，而且还可以保留RhoA平行信号通路所发挥的上游心肌保护作用和收缩能力。纳米材料在疾病治疗中发现了广泛的适用性，因为它们具有调节药物性质的能力，包括循环时间和对感兴趣组织的定位。重要的是，在靶向纳米颗粒中加入治疗部分允许其特定部位的递送，最大限度地减少产生治疗效果所需的剂量，同时减少全身反应。利用这项技术，我们将研究新的靶向配体，用于心肌损伤后心肌纤维化抑制物的细胞特异性递送。利用体内、体外和体外分析，我们将1)产生并充分表征靶向纳米制剂，其中包括用于防止心肌梗塞后胶原沉积的抑制剂；2)检测合成纳米制剂的体外和体内结合和抑制效果；以及3)纵向评估靶向递送抑制剂在心肌梗塞小鼠模型中的治疗效果。重要的是，我们预计这项技术的疗效将超越心肌梗死，并适用于更慢性的疾病，如心肌肥厚和/或瓣膜疾病引起的纤维化。