Identification of causal factors underlying cognitive deficits in a mouse model of childhood leukemia survival

摘要 急性淋巴细胞性白血病(ALL)是最常见的儿童癌症，其存活率现在是 接近90%，但儿童癌症幸存者患长期认知缺陷的风险增加， 尤其影响执行功能(例如，注意力、计划、抑制控制、认知灵活性)。 化疗药物甲氨蝶呤(MTX)用于治疗大多数ALL患者， 与执行功能缺陷有关。因此，迫切需要确定将 MTX暴露于认知功能障碍，以指导制定干预策略，以保护 发展大脑，减轻症状，优化所有幸存者的生活质量，在童年时期， 青春期、青春期和完全成年期。 为此，我们开发了一种与白血病存活的翻译相关的小鼠模型 将癌症暴露(小鼠白血病细胞系L1210细胞)与当代化疗相结合 在生命早期使用药物(长春新碱和甲氨蝶呤，配合亚叶酸钙抢救)。功率因数校正发展 一直延伸到青春期，这使得大脑的这一区域特别容易受到早期生命的影响 化疗。为拟议的实验提供了坚实的前提，我们的小鼠模型概括了 所有患者均观察到执行功能障碍。此外，为了应对早期癌症+ 化疗后，我们发现促炎分子IL-1和CCL2增加，以及 前额叶内脑白质相关基因减少。在目标1中，单细胞RNA测序将是 用于定义癌症和/或化疗对PFC转录图谱的影响。 MTX扰乱叶酸代谢以抑制细胞生长，但这种破坏也会导致水平上升 促炎症代谢物同型半胱氨酸(HCY)在血浆和脑脊液中的含量。增加了 HCY可以促进炎症和氧化应激，并与白质和灰质损伤有关， 以及认知障碍。进一步的执行功能缺陷也与改变有关 突触功能和小胶质细胞，一种脑内常驻免疫细胞，可以通过 CD11b(CR3)-C3吞噬途径。因此，我们假设MTX驱动的HCY增加 水平会导致神经炎症和氧化应激，导致灰质和白质损伤，以及 前额叶皮质突触修剪改变，这是执行功能缺陷的基础。 为了验证这一假设，降低HCY的策略(叶酸和B维生素补充剂，或 抗氧化剂，N-乙酰半胱氨酸酰胺)将在目标2中进行评估。目标3将测试IL-1活性的必要性 而目标4将测试小胶质细胞在调节化疗相关认知过程中的必要性 缺陷，以及神经炎症和氧化应激，导致灰质和白质损伤，以及 前额叶皮质突触修剪的改变

Abstract Survival rates for acute lymphoblastic leukemia (ALL), the most common childhood cancer, are now close to 90%, but survivors of childhood cancer are at an increased risk for long term cognitive deficits, particularly affecting executive function (e.g., attention, planning, inhibitory control, cognitive flexibility). The chemotherapeutic agent methotrexate (MTX) is used to treat most ALL patients, and is closely associated with executive function deficits. Thus a pressing need exists to define the mechanisms that link MTX exposure to cognitive dysfunction, to guide development of intervention strategies to protect the developing brain, reduce symptoms and optimize quality of life in ALL survivors, during childhood, adolescence, young and full adulthood. To that end, we have developed a translationally relevant mouse model of leukemia survival that combines cancer exposure (mouse leukemic cell line (L1210 cells) with contemporary chemotherapeutic drugs (vincristine and MTX, with leucovorin rescue) administered during early life. PFC development extends through adolescence, which renders this area of the brain particularly vulnerable to early life chemotherapy. Providing a solid premise for the proposed experiments, our mouse model recapitulates executive function deficits observed in ALL patients. Additionally, in response to early life cancer + chemotherapy, we have found an increase in the proinflammatory molecules IL-1 and CCL2, as well as a decrease in white matter associated genes within the PFC. In Aim 1, single cell RNA sequencing will be used to define the effects of cancer and/or chemotherapy on the transcriptional profile of the PFC. MTX disrupts folate metabolism to inhibit cell growth, but this disruption also leads to increased levels of the proinflammatory metabolite, homocysteine (HCY), in both plasma and cerebrospinal fluid. Increased HCY can drive inflammation, oxidative stress and is associated with both white and gray matter damage, as well as cognitive impairment. Further executive function deficits have also been linked to altered synaptic function, and microglia, a brain resident immune cell, can contribute to synapse elimination via the CD11b(CR3)-C3 phagocytic pathway. Therefore, we hypothesize that MTX-driven increased HCY levels will lead to neuroinflammation and oxidative stress, leading to gray and white matter damage, and altered synaptic pruning in the prefrontal cortex, which underlie deficits in executive function. To test this hypothesis, HCY-lowering strategies (folate and B vitamin supplementation, or the antioxidant, N-acetylcysteine amide) will be evaluated in Aim 2. Aim 3 will test the necessity of IL-1 activity while Aim 4 will test the necessity of microglia in mediating the chemotherapy-associated cognitive deficits, as well as neuroinflammation and oxidative stress, leading to gray and white matter damage, and altered synaptic pruning in the prefrontal cortex