Immune and muscle cell interactions that modulate dystrophinopathy

描述(申请人提供)：Duchenne肌营养不良症(DMD)是一种致命的肌肉萎缩疾病，由dystrophin基因突变引起。目前DMD患者的治疗选择针对继发性疾病过程，如可能加速疾病进展的炎症。然而，使用免疫抑制剂和合成类固醇的疗法通常会导致长期使用的不良副作用。因此，需要进行旨在了解调节肌肉和免疫系统之间相互作用的细胞和分子机制的研究。我们建议的研究可能有助于开发新的治疗方式，以减少副作用，针对炎症。这项研究的总体目标是使用DMD的MDX小鼠模型来确定肌营养不良症中免疫细胞和肌肉细胞之间的复杂交互作用，以及这些交互作用对肌纤维损伤和再生的影响。我们的具体目的是测试假设，即4周龄的MDX肌肉中的巨噬细胞主要是经典激活的，并通过自由基介导的机制溶解MDX肌管(目标1)。此外，我们的目标是验证再生MDX肌肉中巨噬细胞交替激活并促进肌肉细胞增殖和分化的假设(目标2)。最后，我们将检验这一假设，即体内Th1和Th2细胞因子表达的扰动可以显著影响体内MDX肌肉损伤和修复的过程(目标3)。阐明调节上述相互作用的机制可能导致专门干扰细胞免疫细胞与肌肉相互作用的治疗方法的进步。为了确定这些巨噬细胞表型在体内的生理相关性，我们建议使用各种小鼠模型。我们将通过基因去除IL-10和IFNG来研究Th1和Th2细胞因子在调节MDX肌肉损伤和修复过程中的作用。由于体内研究的解释可能会因调节巨噬细胞功能的众多生理因素而变得复杂，我们将使用体外试验来测试经典激活和交替激活的巨噬细胞促进肌肉细胞死亡和再生的能力。这项研究的结果可能有助于阐明炎症介导的、调节营养不良的病理生理学机制。

DESCRIPTION (provided by applicant): Duchenne muscular dystrophy (DMD) is a lethal, muscle-wasting disorder that is caused by mutations in the dystrophin gene. Current treatment options for DMD patients target secondary disease processes such as inflammation that can accelerate disease progression. However, therapies that employ immuno- suppressants and anabolic steroids commonly result in undesirable side effects with chronic use. Therefore, studies aimed at understanding the cellular and molecular mechanisms that regulate interactions between muscle and the immune system are needed. The investigation we propose may contribute to the development of new therapeutic modalities that target inflammation with reduced side effects. The overall objective of the investigation proposed here is to use the mdx mouse model of DMD to identify complex interactions between immune and muscle cells in muscular dystrophy and the consequences of these interactions on myofiber injury and regeneration. We specifically aim to test the hypothesis that macrophages in 4 week old mdx muscle are predominantly classically-activated and lyse mdx myotubes by free radical-mediated mechanisms (aim 1). In addition, we aim to test the hypothesis that macrophages in regenerative mdx muscle are alternatively-activated and promote muscle cell proliferation and differentiation (aim 2). Lastly, we will test the hypothesis that perturbations in the expression of Th1 and Th2 cytokines in vivo can significantly affect the course of mdx muscle injury and repair in vivo (aim 3). Elucidating the mechanisms that regulate that above interactions may result in the advancement of treatments that specifically perturb cytolytic immune cell interactions with muscle. To determine the physiological relevance of these macrophage phenotypes in vivo we propose using various mouse models. We will study the role of Th1 and Th2 cytokines in regulating the course of mdx muscle injury and repair by genetically ablating IL-10 and IFNg, which differentially regulate macrophage function. Because the interpretation of in vivo studies may be complicated by the numerous physiological factors that regulate macrophage functions, we will use n vitro assays to test the ability of classically- and alternatively-activated macrophages to promote muscle cell death and regeneration. The findings of this investigation may shed light on the inflammation-mediated, pathophysiological mechanisms that regulate dystrophinopathy.