APOPTOSIS IN SKELETAL MUSCLE FOLLOWING BURN INJURY

烧伤后骨骼肌细胞凋亡

基本信息

批准号：
6520273
负责人：
Jeevendra Martyn
金额：
$ 33.72万
依托单位：
MASSACHUSETTS GENERAL HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-03-01 至 2004-02-29
项目状态：
已结题

项目摘要

Burn injury, with and without sepsis, is associated with many functional and metabolic aberrations. In skeletal muscle, the important functional change is muscle weakness resulting in hypoventilation, dependence on respirators, and decreased mobilization. The neuromuscular dysfunction and muscle weakness associated with burns prolongs hospital stay, increases cost, morbidity and mortality. The long-term goals of these studies are, therefore, to characterize the etiology of muscle weakness and design strategies to improve tension-generating capacity of muscle in humans. Based on convincing preliminary data, the hypotheses tested in the present proposal is that apoptosis or programmed cell death occurs in skeletal muscle, at sites distant and immediately local to burn, with activation of pro-apoptotic signaling pathways. The goals of the present studies, using rats, are to: (1) Confirm and study the evolution of apoptosis in skeletal muscle at local and distant sites from burn, and in different fiber types (slow vs. fast twitch muscles). (2) Characterize the putative signaling pathways leading to apoptosis, previously documented only in in vitro systems. (3) Effectively inhibit some of the activated pro-apoptotic pathways and decrease muscle wasting and muscle weakness. Apoptosis will be confirmed by three independent methods- the ladder, TUNEL and ELISA assays. The cell membrane and downstream signaling molecules modulating apoptosis (e.g., TNFalpha, Fas, FasL, phosphatidylinositol 3-kinase, ceramide, BCL-2, BCL-X and caspases) will be assessed for expression and/or activity by using molecular pharmacological or biochemical techniques. The importance of certain signaling molecules will be confirmed by the use of knock out or transgenic (TNF, lpr or Fas, ceramide, BC12, and caspase) mice. Specific exogenous modulators (e.g., IGF-1 and caspase inhibitors) of some of the apoptotic signaling molecules will be used in vivo to attenuate muscle wasting due to apoptosis. These "reversal of apoptosis" studies will be performed in conjunction with protein turnover and functional studies to test the efficacy of these drugs to reverse the neuromuscular dysfunction of burns. The proposed studies will, therefore, delineate the neuromuscular dysfunction associated with burns, the component contributed to by apoptosis, and the potential for attenuation of both the apoptosis and the neuromuscular dysfunction by pharmacotherapy. Information obtained from the rat studies will provide a scientific basis and rationale for therapeutic maneuvers to prevent and/or rectify neuromuscular complications of burns or critical illness in humans.

烧伤，无论是否伴有脓毒症，都与许多功能和代谢异常有关。在骨骼肌中，重要的功能变化是肌肉无力，导致通气不足、依赖呼吸器和活动减少。与烧伤相关的神经肌肉功能障碍和肌肉无力会延长住院时间，增加费用、发病率和死亡率。因此，这些研究的长期目标是确定肌肉无力的病因学特征，并设计提高人类肌肉产生张力的能力的策略。基于令人信服的初步数据，本提案中测试的假设是，凋亡或程序性细胞死亡发生在骨骼肌中，位于远离烧伤部位和紧邻烧伤部位的位置，并激活促凋亡信号通路。目前使用大鼠进行的研究的目的是：（1）确认和研究烧伤局部和远处骨骼肌以及不同纤维类型（慢肌和快肌）细胞凋亡的演变。 (2) 描述导致细胞凋亡的假定信号通路，此前仅在体外系统中记录。 (3) 有效抑制一些激活的促凋亡途径，减少肌肉萎缩和肌无力。细胞凋亡将通过三种独立的方法进行确认——梯子、TUNEL 和 ELISA 测定。将使用分子药理学或生物化学评估调节细胞凋亡的细胞膜和下游信号分子（例如 TNFα、Fas、FasL、磷脂酰肌醇 3-激酶、神经酰胺、BCL-2、BCL-X 和半胱天冬酶）的表达和/或活性技术。某些信号分子的重要性将通过使用敲除或转基因（TNF、lpr 或 Fas、神经酰胺、BC12 和 caspase）小鼠来证实。一些细胞凋亡信号分子的特定外源调节剂（例如 IGF-1 和 caspase 抑制剂）将在体内使用，以减轻细胞凋亡引起的肌肉萎缩。这些“细胞凋亡的逆转”研究将与蛋白质周转和功能研究结合进行，以测试这些药物逆转烧伤神经肌肉功能障碍的功效。因此，拟议的研究将描述与烧伤相关的神经肌肉功能障碍、细胞凋亡造成的成分，以及通过药物治疗减弱细胞凋亡和神经肌肉功能障碍的潜力。从大鼠研究中获得的信息将为预防和/或纠正人类烧伤或危重疾病的神经肌肉并发症的治疗策略提供科学依据和基本原理。