Hydrogen sulfide mechanism of renal hypertension

 描述(申请人提供)：几十年来，硫化氢(H2S)仅因其神经毒性和环境危害而为人所知。然而，最近的研究结果表明，内源性硫化氢具有多种生理功能，生成量的减少会导致血管功能障碍、动脉粥样硬化和高血压。这一发现刺激了对其作为潜在治疗剂的进一步研究，这些疾病归因于硫化氢合成减少。在慢性肾脏疾病中，低水平的血浆硫化氢通常伴随着同型半胱氨酸(Hcy)的增加，称为高同型半胱氨酸血症(HHcy)。众所周知，同型半胱氨酸会导致血管功能障碍。因此，肾脏疾病中HHcy的因果关系可能会对最终结果产生不利影响。由于Hcy是H_2S的前体，H_2S代谢的变化可以对HHcy诱导的病理产生重大影响。然而，HHcy导致血管功能障碍的机制以及硫化氢在肾脏保护中的作用尚不完全清楚。在体内，同型半胱氨酸被三种酶代谢，即胱硫醚β-合成酶(Cbs)、胱硫醚y-裂解酶(Cse)和3-硫代丙酮酸硫转移酶(3MST)，并产生H_2S。在同型半胱氨酸过程中，这些酶的损伤会导致硫化氢产生不足。我们的初步研究表明，HHcy导致小窝蛋白-1表达上调，eNOS同型半胱氨酸化，从而减少NO的产生。由此导致的基质金属蛋白酶及其组织抑制物的失衡导致细胞外基质蛋白的积聚，导致微血管重构、肾功能障碍和高血压。在这个方案中，我们假设H_2S通过抑制小窝蛋白-1和调节eNOS来保护肾脏免受HHcy引起的肾损伤。我们将在体内和体外测试这一假说。野生型(C57BL/6J)和遗传型同型半胱氨酸(CBS+/-)小鼠将不添加或添加硫化氢。为了确定同型半胱氨酸的影响是否依赖于小窝蛋白-1，我们将使用小窝蛋白-1-/-小鼠补充高同型半胱氨酸饮食。为了改善HHcy诱导的损伤，采用CBS、CSE和3MST酶的单、双或三基因传递系统将被用来促进Hcy向H_2S的转化。除了证实初步结果外，还将进行进一步的研究，以更深入地了解硫化氢对HHcy促纤维化和促炎作用所致的肾血管功能障碍的改善作用。这项研究是新颖的，因为它评估了基因传递作为一种治疗选择来改善HHcy诱导的微血管重构、肾功能障碍和高血压。

 DESCRIPTION (provided by applicant): For decades, hydrogen sulfide (H2S) was known only for its neurotoxicity and as an environmental hazard. Recent findings however, suggest that endogenous H2S has a variety of physiological functions and a decrease in production can lead to vascular dysfunction, atherosclerosis and hypertension. This discovery has stimulated further research into its development as a potential therapeutic agent in diseases attributed to diminished H2S synthesis. In chronic kidney disease, low levels of plasma H2S is often associated with a concomitant increase in homocysteine (Hcy), known as hyperhomocysteinemia (HHcy). HHcy is well known to cause vascular dysfunction. The cause and effect relationship of HHcy in renal disease can therefore adversely affect the final outcome. Because Hcy is a precursor of H2S, changes in the H2S metabolism can have a significant impact on HHcy-induced pathology. However, the mechanism by which HHcy causes vascular dysfunction and the role of H2S in renal protection is incompletely understood. In the body, Hcy is metabolized by three enzymes, cystathionine β-synthase (CBS), cystathionine y-lyase (CSE) and 3- mercaptopyruvate sulfurtransferase (3MST) and produce H2S. During HHcy, an impairment in these enzymes leads to deficient H2S production. Our preliminary studies suggest that HHcy results in upregulation of caveolin-1 and homocysteinylation of eNOS thus decreasing NO production. The resulting imbalance in matrix metalloproteinases and their tissue inhibitors of metalloproteinases causes accumulation of extracellular matrix proteins leading to microvascular remodeling, renal dysfunction and hypertension. In this proposal, we hypothesize that H2S offers renal protection from HHcy-induced renal damage by inhibition of caveolin-1 and modulation of eNOS. We will test this hypothesis in vivo and in vitro. Wild type (C57BL/6J) and genetic model of HHcy (CBS+/-) mice will be supplemented without or with H2S. To determine whether HHcy effects are caveolin-1 dependent we will use caveolin-1-/- mice supplemented with high Hcy diet. To ameliorate the HHcy- induced injury, single, double or triple gene delivery system employing CBS, CSE and 3MST enzymes will be used to enhance conversion of Hcy to H2S. In addition to confirming the preliminary findings, further studies will be performed for a deeper understanding into H2S-mediated improvement in renovascular dysfunction caused by pro-fibrotic and pro-inflammatory effects of HHcy. This research is novel because it evaluates gene delivery as a therapeutic option to ameliorate HHcy-induced microvascular remodeling, renal dysfunction and hypertension.