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展。 初步结果表明，腺苷（ADO）可抑制心脏成纤维细胞（CF）的功能。 这些作用似乎是通过ADO A2 b受体介导的。 我们将检验以下假设：“心肌腺苷水平的提高通过刺激心脏成纤维细胞腺苷A2 b受体减少心脏胶原蛋白的合成和相关的纤维化”。 我们将研究以下目的：目的1：在心肌梗死（MI）的情况下，增加心肌ADO水平抑制心脏胶原的沉积。 我们将通过MI诱导的瘢痕形成诱导大鼠心脏胶原的急性沉积。 为了提高组织ADO水平，我们将使用ADO激酶抑制剂化合物GP 515。 我们将通过测定被动和主动结构-功能以及通过分析瘢痕的显微结构特性来评估在对照未治疗和治疗的MI大鼠中抑制瘢痕形成的功能后果。 目的2：心肌梗死时增加的心肌ADO水平降低了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在转基因小鼠中诱导心脏成纤维细胞增殖和胶原沉积，所述转基因小鼠将标记物绿色荧光蛋白（GFP）的表达与I型胶原（CI-GFP）基因表达联系起来。 心肌ADO水平将如目标1中那样增强。 将在预定时间点评估体内CF增殖、I型基因表达和心脏功能、瘢痕形成/重塑。 目标3：MI小鼠心脏中A2 b受体的缺乏损害了ADO减少心脏胶原合成的能力，从而产生增强的瘢痕沉积。 我们将使用A2 b受体无效（-/-）小鼠。 我们将通过使用MI在野生型和A2 b受体缺失小鼠中诱导心脏胶原的急性沉积。 组织ADO水平将按照目标1提高。 将在预定时间点评估心脏被动和主动结构-功能。 还将使用来自A2 b（-/-）小鼠的培养的CF在体外检查增强的ADO水平的作用，并评估细胞功能的ADO调节。 目标4：ADO通过刺激A2 b受体和cAMP和/或cGMP水平的相关增加来抑制TNF-α释放和心脏成纤维细胞功能。 我们将评估腺苷A2 b受体介导的CF功能的诱导抑制以及细胞内cAMP和/或cGMP在介导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.