Respiratory Muscle Weakness in Chronic Inflammation

描述(由申请人提供)：在这个补充项目中，我们寻求利用令人兴奋的新数据、创新技术和三个新合作者的独特专业知识的融合。来自我们母项目的数据已经确定，一种鲜为人知的鞘磷脂酶亚型-中性鞘磷脂酶-3(nSMase-3)-是由肿瘤坏死因子刺激的横隔膜无力或严重心力衰竭的潜在介体。我们建议通过多学科策略来检验这一论点。实验方法包括细胞培养系统，新创建的转基因小鼠系，以及心力衰竭患者的横隔膜活检。该项目由三名新的合作者组成的强大团队使之成为可能，他们都是分子生物学、移植外科和人类遗传学方面的专家。我们项目的目标是评估nSMase-3作为心力衰竭时膈肌无力的潜在介体和未来治疗开发的靶点。我们有两个特定的目的：目的1.评价nSMase-3在肿瘤坏死因子诱导的氧化剂活性和强度中的作用。实验1.1将验证nSMase-3由小鼠骨骼肌结构性表达并被肿瘤坏死因子上调的假设。实验1.2将验证肌肉特异性nSMase-3缺乏将消除肿瘤坏死因子对隔膜氧化剂活性和比力的影响的假设。目的2.检测nSMase-3与人类心血管疾病之间的关系。实验2.1将验证这样一种假设，即心力衰竭手术患者的横隔肌和胸肌中nSMase-3mRNA、nSMase-3蛋白和sMase活性升高。实验2.2将验证这样一个假设，即编码nSMase-3的Smpd4基因中的单核苷酸多态(SNPs)将调节该基因在人类组织中的表达或剪接。 公共卫生相关性：慢性心肺疾病患者的呼吸肌无力和疲劳会导致运动不耐受、呼吸困难和呼吸衰竭。这个补充项目测试了一种新的酶，中性鞘磷脂酶-3，作为慢性疾病呼吸肌功能障碍的可能原因和未来治疗的潜在靶点。

DESCRIPTION (provided by applicant): In this supplemental project, we seek to capitalize on a confluence of exciting new data, innovative technology, and the unique expertise of three new collaborators. Data from our parent project have identified an obscure sphingomyelinase isoform -- neutral sphingomyelinase-3 (nSMase-3) -- as a potential mediator of diaphragm weakness stimulated by TNF or severe heart failure. We propose to test this thesis by a multidisciplinary strategy. The experimental approach includes cell culture systems, a newly-created transgenic mouse line, and diaphragm biopsies from humans with heart failure. The project is made possible by a powerful team of three new collaborators who are experts in molecular biology, transplantation surgery, and human genetics. The goal of our project is to evaluate nSMase-3 as a potential mediator of diaphragm weakness in heart failure and a target for future therapeutic development. We have two specific aims: Aim 1. To evaluate nSMase-3 as a mediator of TNF-induced oxidant activity and weakness. Experiment 1.1 will test the hypothesis that nSMase-3 is constitutively expressed by murine skeletal muscle and is upregulated by TNF. Experiment 1.2 will test the hypothesis that muscle-specific nSMase-3 deficiency will abolish TNF effects on diaphragm oxidant activity and specific force. Aim 2. To test for associations between nSMase-3 and cardiovascular disease in humans. Experiment 2.1 will test the hypothesis that nSMase-3 mRNA, nSMase-3 protein, and SMase activity are elevated in diaphragm and pectoralis muscles of patients undergoing surgery for heart failure. Experiment 2.2 will test the hypothesis that single nucleotide polymorphisms (SNPs) in the Smpd4 gene that codes for nSMase-3 will modulate expression or splicing of the gene in human tissue. PUBLIC HEALTH RELEVANCE: Weakness and fatigue of the respiratory muscles cause exercise intolerance, breathlessness, and respiratory failure in patients with chronic heart and lung diseases. This supplemental project tests a novel enzyme, neutral sphingomyelinase-3, as a possible cause of respiratory muscle dysfunction in chronic disease and a potential target for future therapies.