Circadian regulation of cancer therapy-associated neuroinflammation

癌症治疗的最新进展提高了许多儿童和成人癌症的生存率。通过 到2023年，超过2000万癌症幸存者将生活在美国。不幸的是，绝大多数 个体将表现出持续神经缺陷的一些迹象，临床上称为癌症治疗， 相关认知障碍（CRCI）。这些损伤包括记忆、学习、注意力、 执行功能、信息处理、语言和多任务处理。尽管有无数怀疑的原因， CRCI的主要共同点之一是癌症治疗后持续的神经炎症状态。如何 这种持续的神经炎症介导的仍然是我们理解潜在的 CRCI生物学我们之前在临床前小鼠模型中的工作表明， 化疗剂甲氨蝶呤（MTX）诱导依赖于直接免疫抑制剂的三神经胶质细胞失调。 激活小胶质细胞，即中枢神经系统的常驻免疫细胞。全身MTX给药 导致持续的小胶质细胞泛激活，促进星形胶质细胞反应性并降低OPC密度 并分化成髓鞘形成的少突胶质细胞，导致髓鞘变薄。甲氨蝶呤诱导的异常 髓鞘形成导致与CRCI相关的持续性认知缺陷，包括短期内的减少。 记忆力和注意力在治疗后长达六个月。我们实验室的初步数据表明， 小胶质细胞活化和随后的少突胶质细胞谱系细胞的失调，是时间依赖性的， 这表明持续的小胶质细胞活化和与CRCI相关的临床缺陷可能受到调节， 以昼夜节律的方式，因此易受时间调节的影响。本提案的目的是确定 如果MTX化疗驱动小胶质细胞转录组的内在变化并改变其结构或功能， 维持与CRCI相关的小胶质细胞的活化。我们的核心假设是， 化疗诱导的慢性神经炎症是由小胶质细胞的昼夜节律调节和 BBB.我们检验这一假设的方法是在体外和体内将小胶质细胞暴露于MTX化疗， 不同的昼夜节律阶段，并分析分离的小胶质细胞和BBB内皮细胞的转录谱， 以及评估BBB渗透性和完整性。这种方法的基本原理是， 这一结果将有助于对生物体内在和微环境调节剂的机理理解。 癌症治疗后的神经炎性小胶质细胞。在完成这项建议后，我们预计 确定了昼夜节律调节如何决定小胶质细胞对化疗的激活。仍然迫切 需要确定神经炎症介导持续性神经系统损伤的潜在机制， CRCI在癌症治疗的临床前模型中的失调。如果没有这种知识， 旨在减轻神经炎症的治疗策略仍然是难以捉摸的， 神经系统缺陷将继续成为癌症幸存者和我们的医疗保健系统的实质性负担。

Recent advances in cancer therapy have increased survivability of numerous pediatric and adult cancers. By 2023, over 20 million cancer survivors will live in the United States. Unfortunately, the vast majority of these individuals will exhibit some indication of sustained neurological deficiency, clinically called cancer therapy- related cognitive impairment (CRCI). These impairments include deficits in memory, learning, attention, executive function, information processing, language, and multitasking. Despite the myriad suspected causes of CRCI, one of the main commonalities is a persistent neuroinflammatory state following cancer treatment. How this sustained neuroinflammation is mediated remains a critical gap in our understanding of the underlying biology of CRCI. Our previous work in a preclinical mouse model demonstrated that the commonly used chemotherapeutic agent, methotrexate (MTX), induces tri-glial dysregulation that is dependent on the direct activation of microglia, the resident immune cells of the central nervous system. Systemic MTX administration results in persistent microglial pan activation which promotes astrocyte reactivity and decreased OPC density and differentiation into myelin-forming oligodendrocytes, leading to thinner myelin. MTX-induced aberrant myelination causes persistent cognitive deficits associated with CRCI, including decrements in short-term memory and attention for up to six months post-treatment. Preliminary data from our lab demonstrates that this microglial activation, and consequent dysregulation of oligodendrocyte lineage cells, is time-of-day dependent, suggesting that the sustained microglial activation and clinical deficiency associated with CRCI may be regulated in a circadian manner and thus susceptible to chronomodulation. The objective of this proposal is to determine if MTX chemotherapy drives intrinsic changes to the microglial transcriptome and alters the structure or function of the BBB to sustain the activation of microglia associated with CRCI. Our central hypothesis is that chemotherapy-induced chronic neuroinflammation is modulated by circadian regulation of microglia and the BBB. Our approach to testing this hypothesis is to expose microglia in vitro and in vivo to MTX chemotherapy at different circadian phases and analyze the transcriptional profile of isolated microglia and BBB endothelial cells, as well as assess BBB permeability and integrity. The rationale for this approach is that information gleaned from the results will contribute mechanistic understanding into the intrinsic and microenvironmental modulators of neuroinflammatory microglia following cancer therapy. Upon completion of this proposal, we expect to have identified how circadian modulation dictates microglial activation to chemotherapy. There remains an urgent need to define the underlying mechanisms of neuroinflammation mediating the persistent neurological dysregulation in CRCI in preclinical models of cancer therapy. In the absence of such knowledge, effective therapeutic strategies aimed at mitigating neuroinflammation will remain elusive and subsequent sustained neurological deficits will continue to be a substantive burden to cancer survivors and our healthcare system.