Adenosine Mediated Modulation of Cardiac Fibrosis

心肌纤维化可导致舒张功能障碍和心力衰竭的发生。初步结果表明，腺苷（ADO）能抑制心肌成纤维细胞（CF）的功能。这些作用似乎是通过ADO A2b受体介导的。我们将验证以下假设：“心肌腺苷水平的增强通过刺激心脏成纤维细胞腺苷A2b受体减少心脏胶原合成和相关纤维化”。我们将研究以下目的：目的1：心肌梗死（MI）时心肌ADO水平升高可抑制心肌胶原沉积。我们将通过心肌梗死诱导瘢痕形成来诱导大鼠心肌胶原的急性沉积。为了提高组织ADO水平，我们将使用ADO激酶抑制剂化合物GP515。我们将通过确定被动和主动结构-功能以及分析疤痕的微观结构特性来评估控制未治疗和治疗的心肌梗死大鼠瘢痕形成的功能后果。AIM 2：心肌梗死时心肌ADO水平升高可降低体内心肌成纤维细胞增殖和I型胶原基因转录。我们将使用MI诱导转基因小鼠的心脏成纤维细胞增殖和胶原沉积，这些转基因小鼠将标记绿色荧光蛋白（GFP）的表达与I型胶原（CI- GFP）基因表达联系起来。心肌ADO水平与目的1一样升高。体内CF增殖、I型基因表达和心功能、疤痕/重塑将在预定的时间点进行评估。AIM 3：心肌梗死小鼠心脏中A2b受体的缺失会损害ADO减少心脏胶原合成的能力，从而增强疤痕沉积。我们将使用小鼠null（-/-）作为A2b受体。我们将在野生型和A2b受体缺失小鼠中使用MI诱导心肌胶原的急性沉积。组织ADO水平将与目的1一样提高。在预定的时间点评估心脏被动和主动结构功能。提高ADO水平的影响也将通过体外培养的A2b（-/-）小鼠CF来检验，并评估ADO对细胞功能的调节。AIM 4: ADO通过刺激A2b受体及相关cAMP和/或cGMP水平升高抑制tnf - α释放和心脏成纤维细胞功能。我们将评估腺苷A2b受体介导的CF功能诱导抑制，以及细胞内cAMP和/或cGMP在ADO诱导的CF功能改变中的作用。

Myocardial fibrosis can contribute to diastolic dysfunction and the development of heart failure. Preliminary results indicate that adenosine (ADO) can inhibit cardiac fibroblast (CF) function. These effects appear mediated via ADO A2b receptors. We will test the hypothesis that: "The enhancement of myocardial adenosine levels reduces the synthesis of cardiac collagens and associated fibrosis through the stimulation of cardiac fibroblast adenosine A2b receptors". We will examine the following aims: AIM 1: Enhanced myocardial ADO levels in the setting of myocardial infarction (MI) inhibits the deposition of cardiac collagens. We will induce the acute deposition of cardiac collagens in rats via MI induced scar formation. To enhance tissue ADO levels we will use the ADO kinase inhibitor compound GP515. We will assess for the functional consequences of the inhibition of scar formation in control untreated and treated MI rats by determining passive and active structure-function and by analysis of the microstructural properties of the scar. AIM 2: Enhanced myocardial ADO levels in the setting of MI reduces in vivo cardiac fibroblast proliferation and type I collagen gene transcription. We will use MI to induce cardiac fibroblast proliferation and collagen deposition in transgenic mice that link the expression of the marker green fluorescent protein (GFP) to collagen type I (CI- GFP) gene expression. Myocardial ADO levels will be enhanced as in aim 1. In vivo CF proliferation, type I gene expression and cardiac function, scarring/remodeling will be assessed at predetermined time points. AIM 3: The absence of A2b receptors in the MI mouse heart impairs the ability of ADO to diminish cardiac collagen synthesis yielding enhanced scar deposition. We will use mice null (-/-) for A2b receptors. We will induce the acute deposition of cardiac collagens in wild type and in A2b receptor null mice by using MI. Tissue ADO levels will be enhanced as in aim 1. Cardiac passive and active structure- function will be assessed at predetermined time points. The effects of enhanced ADO levels will also be examined in vitro using cultured CF from A2b (-/-) mice and assessing for ADO modulation of cell function. AIM 4: ADO inhibits TNF-alpha release and cardiac fibroblast function through the stimulation of A2b receptors and associated increases in cAMP and/or cGMP levels. We will assess for adenosine A2b receptor mediated induced inhibition of CF function and for the role of intracellular cAMP and/or cGMP in mediating ADO induced alterations in CF function.