Abstract：
Microglia are increasingly recognized to contribute to brain health and disease. Preclinical studies using laboratory rodents are essential to advance our understanding of the physiological and pathophysiological roles of these cells in the central nervous system. Rodents are nocturnal animals, and they are mostly maintained in a defined light-dark cycle within animal facilities, with many laboratories investigating the molecular and functional profiles of microglia exclusively during the animals\' light (sleep) phase. However, only a few studies have considered possible differences in microglial functions between the active and sleep phases. Based on initial evidence suggesting that microglial intrinsic clock genes can affect their phenotypes, we sought to investigate differences in transcriptional, proteotype and functional profiles of microglia between light (sleep) and dark (active) phases, and how these changes are affected in pathological models. We found marked transcriptional and proteotype differences between microglia harvested from male mice during the light or dark phase. Amongst others, these differences related to genes and proteins associated with immune responses, motility, and phagocytosis, which were reflected by functional alterations in microglial synaptic pruning and response to bacterial stimuli. Possibly accounting for such changes, we found RNA and protein regulation in SWI/SNF and NuRD chromatin remodeling complexes between light and dark phases. Importantly, we also show that the time of microglial sample collection influences the nature of microglial transcriptomic changes in a model of immune-mediated neurodevelopmental disorders. Our findings emphasize the importance of considering diurnal factors in studying microglial cells and indicate that implementing a circadian perspective is pivotal for advancing our understanding of their physiological and pathophysiological roles in brain health and disease.
摘要：
小胶质细胞越来越被认为有助于大脑健康和疾病。使用实验室啮齿动物的临床前研究对于促进我们对中枢神经系统中这些细胞的生理和病理生理功能的理解至关重要。啮齿动物是夜行动物，它们大多在动物设施内保持在一个确定的明暗循环中，许多实验室研究了动物光照（睡眠）阶段的小胶质细胞分子和功能概况。然而,只有少数研究考虑了活动期和睡眠期之间小胶质细胞功能的可能差异.根据初步证据表明小胶质细胞内在时钟基因可以影响其表型，我们试图研究转录差异，光（睡眠）和暗（活动）阶段之间的小胶质细胞的蛋白质型和功能谱，以及这些变化如何在病理模型中受到影响。我们发现在明暗阶段从雄性小鼠收获的小胶质细胞之间存在明显的转录和蛋白质型差异。其中,这些差异与免疫反应相关的基因和蛋白质有关，运动性,和吞噬作用，这反映在小胶质细胞突触修剪和对细菌刺激的反应中。可能考虑到这种变化，我们在SWI/SNF和NuRD染色质重塑复合物中发现了RNA和蛋白质的调节，介于光期和暗期之间。重要的是,我们还表明,在免疫介导的神经发育障碍模型中,小胶质细胞样本采集的时间会影响小胶质细胞转录组变化的性质.我们的发现强调了在研究小胶质细胞时考虑昼夜因素的重要性，并表明实施昼夜节律观点对于提高我们对其在大脑健康和疾病中的生理和病理生理作用的理解至关重要。
