The Role of Microglia in Models of ALS

描述（由申请人提供）：肌萎缩侧索硬化症（ALS）是一种进展迅速且致命的神经肌肉疾病;大约10%的ALS患者有该疾病的家族史。这些家族性ALS病例中有20-25%是由Cu 2 +/Zn 2+超氧化物歧化酶基因（mSOD 1）突变引起的。mSOD 1在转基因小鼠中的过表达在广泛表达时也诱导疾病。然而，有证据表明，除了运动神经元之外，可能需要其他细胞来产生ALS表型，即非细胞自主。首先，仅在神经元和仅在星形胶质细胞中表达mSOD 1不会产生疾病;然而，mSOD 1表达的水平和时间与原始mSOD 1G 93 A小鼠不同。第二，嵌合小鼠的数据表明，mSOD 1表达神经元周围的正常胶质细胞似乎未受损伤，而正常神经元周围的mSOD表达胶质细胞出现异常。第三，病理学存在于CNS中的几种不同细胞类型中，包括神经元、星形胶质细胞和小胶质细胞。为了确定mSOD 1表达在ALS中小胶质细胞和免疫细胞中的作用，我们选择使用PU.1-/-小鼠。出生时，这些小鼠缺乏巨噬细胞、中性粒细胞、T和B细胞，重要的是缺乏小胶质细胞;这些小鼠仅在骨髓移植后存活，导致供体来源的CNS小胶质细胞。具体而言，我们的目标是：具体目标1：确定mSOD 1在小胶质细胞和免疫细胞中的单独表达是否可诱导ALS样疾病和/或引发亚临床病理学。我们正在用mSOD 1-、正常人（h）SOD 1和野生型来源的骨髓移植PU.1 -/-小鼠。移植mSOD 1骨髓的PU. 1-/-小鼠似乎没有表现出任何明显的运动神经元疾病的迹象;即使移植的小胶质细胞在形态上可能不同于对照小鼠中的小胶质细胞。我们将检查这些小鼠的亚临床病理学。具体目标二：确定mSOD 1小鼠中ALS样疾病的起始和/或扩增是否需要小胶质细胞和免疫细胞中的mSOD 1表达。我们正在移植mSOD 1小鼠与PU. 1-/-小鼠（mSOD 1/PU.I-/-）杂交。移植野生型骨髓的mSOD 1/PU.1 -/-小鼠表现出ALS样表型。有趣的是，这几只小鼠的疾病持续时间可能长于mSOD 1/PU.1 -/-小鼠移植mSOD 1骨髓的持续时间。具体目标3：确定小胶质细胞介导的运动神经元损伤的潜在机制。我们正在培养被激活的野生型小胶质细胞损伤的原代运动神经元，mSOD 1原代小胶质细胞似乎更活跃，我们将评估它们损伤野生型和mSOD 1运动神经元的能力。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neuromuscular disease; approximately 10% of ALS patients have a family history of the disease. 20-25% of these familial ALS cases are caused by mutations in the Cu2+/Zn2+ superoxide dismutase gene (mSOD1). Overexpression of mSOD1 in transgenic mice also induces disease when ubiquitously expressed. However, evidence indicates that other cells, in addition to motor neurons, may be required to produce an ALS phenotype, i.e. non-cell autonomous. First, expression of mSOD1 in neurons-only and in astroglia-only did not produce disease; however, the level and timing of mSOD1 expression were not the same as the original mSOD1G93A mouse. Second, data from chimeric mice suggest that mSOD1-expressing neurons surrounded by normal glia appear uninjured, whereas normal neurons surrounded by mSOD-expressing glia appear abnormal. Third, pathology is present in several different cell types in the CNS, including neurons, astrocytes, and microglia. To determine the effects of mSOD1 expression in microglia and immune cells in ALS, we chose to use the PU.1-/- mouse. At birth, these mice lack macrophages, neutrophils, T and B cells, and importantly microglia; such mice survive only after bone marrow transplantation, resulting in donor-derived CNS microglia. Specifically, our aims are: Specific Aim 1: To determine if mSOD1 expression in microglia and immune cells alone can induce an ALS-like disease and/or initiate subclinical pathology. We are transplanting PU.1 -/- mice with mSOD1-, normal human (h)SOD1, and wildtype-derived bone marrow. PU.1 -/- mice transplanted with mSOD1 bone marrow did not appear to show any overt signs of motoneuron disease; even though the transplanted microglia may be morphologically different than microglia in control mice. We will examine these mice for subclinical pathology. Specific Aim 2: To determine if mSOD1 expression in microglia and immune cells is required for the initiation and/or amplification of an ALS-like disease in the mSOD1 mouse. We are transplanting the mSOD1 mice crossed with the PU.1 -/- mice (mSOD1/PU.I-/-). mSOD1/PU.1 -/- mice transplanted with wildtype bone marrow exhibit an ALS-like phenotype. Interestingly, the disease duration with these few mice may be longer than the duration of the mSOD1/PU.1 -/- mice transplanted with mSOD1 bone marrow. Specific Aim 3: To define potential mechanisms of microglia-mediated motor neuron injury. We are culturing primary motor neurons, which are injured by activated wildtype microglia, mSOD1 primary microglia appear more activated and we will assess their ability to injure wildtype and mSOD1 motor neurons.