Estrogen and Abdominal Muscle Fibrosis

尽管预计每4名男性中就有1人会出现症状性腹股沟疝气，但其机制是 目前尚不清楚。由于肌肉纤维化和肌纤维萎缩导致的一组腹股沟疝气 下腹壁无力。这种应用的长期目标是确定雌激素的作用。 在下腹部肌肉组织(LAMT)纤维化和萎缩的病因学中的作用 腹股沟疝气。将睾丸激素转化为雌二醇的芳香化酶只在大脑和睾丸中表达。 雄鼠的数量。然而，在男性中，芳香化酶在许多额外的组织(肌肉、脂肪)中表达，以提供 生理上必需的局部剂量的雌激素。我们产生了转基因人源化芳香酶 (Aromhum)小鼠品系，每个品系都包含一个全长人类芳香酶基因的单一副本，包括其 调节区域，以模仿人类产生雌激素的模式。芳香族小鼠表达芳香酶基因 在外周组织中，包括骨骼肌组织的成纤维细胞成分。LAMT已被发现 对雌二醇比上腹部或股四头肌更敏感，因为LAMT的间质 含有大量表达雌激素受体-(ER-)的成纤维细胞。本地增长 LAMT中雌二醇浓度与以进行性LAMT纤维化为特征的LAMT相关 用富含ER的成纤维细胞和过量的细胞外基质取代萎缩的肌细胞(肌肉纤维)， 结果在24周时，90%的阿罗姆雄性小鼠形成了巨大的腹股沟腹股沟疝气。然而，在那里 在任何野生型(WT)产仔中均未观察到腹股沟。LAMT基因的微阵列表达分析 四周(在出现疝气之前)，在Aromhum和WT小鼠中显示了激活的促纤维化通路。 我们假设，局部形成的雌二醇引起的雌激素作用增强会推动肌肉纤维化和 肌细胞萎缩，导致影响骨骼高度雌激素敏感部分的疝表型 肌肉组织，这是阿罗姆小鼠的LAMT。这与显著的平行增长产生了共鸣 老年男性腹股沟疝气发生率和骨骼肌和脂肪中芳香化酶表达增加。至 为了弄清潜在的机制，我们提出了以下目标：1.确定是否用一种 芳香酶抑制剂、雌二醇拮抗剂或高选择性ERα拮抗剂预防纤维化 阿罗姆小鼠肌肉萎缩和腹股沟形成。雌激素/雌激素受体介导的基因组机制 对成纤维细胞无序增殖和细胞外基质形成的责任将通过 Rna-seq和ER--chIP-seq对LAMT和成纤维细胞的整合分析。2.确定是否 选择性破坏骨骼肌成纤维细胞ER基因影响肌筋膜成纤维细胞纤维化和疝气形成 在阿罗姆小鼠身上。同时，我们将评估组织类固醇水平、芳香酶和ER的表达，以及雌激素 有无疝气男性腹肌活检中的反应基因。我们预计这部小说 该提案将确定新的药物靶点，并可能导致发现预防腹股沟疝气的方法 高危人群。

Although more than 1 in 4 men can be expected to develop symptomatic inguinal hernia, its mechanism is currently unknown. A subset of hernias may develop due to muscle fibrosis and myofiber atrophy leading to lower abdominal wall weakness. The long-term objective of this application is to determine the role of estrogen action in the etiology of lower abdominal muscle tissue (LAMT) fibrosis and atrophy associated with a subset of inguinal hernias. Aromatase, which converts testosterone to estradiol, is expressed only in the brain and testes of male mice. However, in men, aromatase is expressed in many additional tissues (muscle, fat) to provide physiologically necessary local quantities of estrogen. We generated transgenic humanized aromatase (Aromhum) mouse lines, each containing a single copy of the full-length human aromatase gene including its regulatory region, to mimic human patterns of estrogen production. Aromhum mice express the aromatase gene in peripheral tissues including the fibroblast component of the skeletal muscle tissue. LAMT has been found to be more sensitive to estradiol than the upper abdominal or quadriceps muscles, because the stroma of LAMT contains strikingly larger amounts of estrogen receptor- (ER)-expressing fibroblasts. Locally increased concentrations of estradiol in LAMT was associated with LAMT fibrosis characterized by progressive replacement of atrophic myocytes (muscle fibers) with ER-rich fibroblasts and excessive extracellular matrix, resulting in formation of large inguinal hernias in >90% of Aromhum male mice by 24 weeks. However, there were no hernias observed in any of the wild-type (WT) littermates. Microarray expression analysis of LAMT at four weeks (before the appearance of hernias) showed activated profibrotic pathways in Aromhum vs. WT mice. We hypothesize that enhanced estrogen action caused by locally formed estradiol drives muscle fibrosis and myocyte atrophy, leading to the hernia phenotype affecting highly estrogen-sensitive portions of skeletal muscle tissue, which is LAMT in Aromhum mice. This resonates with the remarkable and parallel increases in inguinal hernia incidence and increased aromatase expression in skeletal muscle and fat in aging men. To ascertain the underlying mechanisms, we propose the following aims: 1. Determine whether treatment with an aromatase inhibitor, an estradiol antagonist, or a highly selective ERα antagonist prevents fibrosis, LAMT muscle atrophy, and hernia formation in Aromhum mice. The estradiol/ER-mediated genomic mechanisms responsible for disordered proliferation of fibroblasts and extracellular matrix formation will be determined using integrative analysis of RNA-seq and ER-ChIP-seq on LAMT and fibroblasts. 2. Determine whether the genetic disruption of ER selectively in skeletal muscle fibroblasts affects LAMT fibrosis and hernia formation in Aromhum mice. In parallel, we will assess tissue steroid levels, aromatase and ERexpression, and estrogen responsive genes in abdominal muscle biopsies of men with or without hernia. We anticipate that this novel proposal will identify new drug targets and likely lead to the discovery of preventive approaches for hernia in high-risk populations.