This study aims to determine whether sickle cell mice could recapitulate features of cognitive and neurobehavioral impairment observed in sickle cell patients and whether neuroinflammation could be a potential therapeutic target as in other non-sickle cell disease-related cognitive dysfunction. Cognitive (learning and memory) and behavioral (anxiety) deficits in 13- and later 6-month-old male Townes humanized sickle cell (SS) and matched control (AA) mice were evaluated using novel object recognition (NOR) and fear conditioning tests. Immunohistochemistry was performed to quantify peripheral immune cell (CD45⁺) and activated microglia (Iba1⁺) as markers of neuroinflammation in the dentate and peri-dentate gyrus areas. We evaluated cell fate by measuring 5'-bromodeoxyuridine and doublecortin fluorescence and phenotyped proliferating cells using either glial fibrillary acid protein (GFAP⁺), neuronal nuclei (NeuN⁺), CD45⁺, and Iba1⁺. In addition, Golgi-Cox staining was used to assess markers of neuroplasticity (dendritic spine density and morphology and density of dendrite arbors) on cortical and hippocampal pyramidal neurons. Compared to matched AA controls, 13-month-old SS mice showed significant evidence of cognitive and behavioral deficit on NOR and fear conditioning tests. Also, SS mice had significantly higher density of CD45⁺ and activated microglia cells (i.e. more evidence of neuroinflammation) in the dentate and peri-dentate gyrus area. Additionally, SS mice had significantly lower dendritic spine density, but a higher proportion of immature dendritic spines. Treatment of 13-month-old SS mice with minocycline resulted in improvement of cognitive and behavioral deficit compared to matched vehicle-treated SS mice. Also, treated SS mice had significantly fewer CD45⁺ and activated microglia cells (i.e. less evidence of neuroinflammation) in the dentate and peri-dentate gyrus, as well as a significant improvement in markers of neuroplasticity.

Impact statement

This study provides crucial information that could be helpful in the development of new or repurposing of existing therapies for the treatment of cognitive deficit in individuals with sickle cell disease (SCD). Its impact is in demonstrating for the first time that neuroinflammation and along with abnormal neuroplasticity are among the underlying mechanism of cognitive and behavioral deficits in SCD and that drugs such as minocycline which targets these pathophysiological mechanisms could be repurposed for the treatment of this life altering complication of SCD.

中文翻译：

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年龄和神经炎症在镰状细胞病认知缺陷机制中的作用。

本研究旨在确定镰状细胞小鼠是否能够重现在镰状细胞患者中观察到的认知和神经行为障碍的特征，以及神经炎症是否可以像其他非镰状细胞病相关的认知功能障碍一样成为潜在的治疗目标。使用新物体识别 (NOR) 和恐惧条件反射测试评估 13 个月及以后 6 个月大的雄性 Townes 人源化镰状细胞 (SS) 和匹配对照 (AA) 小鼠的认知（学习和记忆）和行为（焦虑）缺陷. 进行免疫组织化学以量化外周免疫细胞 (CD45 ⁺ ) 和活化的小胶质细胞 (Iba1 ⁺) 作为齿状回和齿状回区域神经炎症的标志物。我们通过测量 5'-溴脱氧尿苷和双皮质素荧光以及使用胶质纤维酸性蛋白 (GFAP ⁺ )、神经元核 (NeuN ⁺ )、CD45 ⁺和 Iba1 ^{+ 对}增殖细胞进行表型来评估细胞命运。此外，高尔基-考克斯染色用于评估皮层和海马锥体神经元的神经可塑性标志物（树突棘密度和树突乔木的形态和密度）。与匹配的 AA 对照相比，13 个月大的 SS 小鼠在 NOR 和恐惧条件反射测试中表现出明显的认知和行为缺陷。此外，SS 小鼠的 CD45 ⁺密度显着更高和激活的小胶质细胞（即神经炎症的更多证据）在齿状回和齿状回区域。此外，SS 小鼠的树突棘密度显着降低，但未成熟树突棘的比例更高。与匹配的载体治疗的 SS 小鼠相比，用米诺环素治疗 13 个月大的 SS 小鼠导致认知和行为缺陷的改善。此外，经处理的 SS 小鼠在齿状回和齿状回中具有显着较少的 CD45 ⁺和活化的小胶质细胞（即较少的神经炎症证据），以及神经可塑性标志物的显着改善。

影响陈述

这项研究提供了重要信息，可能有助于开发新疗法或重新利用现有疗法来治疗镰状细胞病 (SCD) 患者的认知缺陷。它的影响是首次证明神经炎症和异常的神经可塑性是 SCD 认知和行为缺陷的潜在机制之一，而针对这些病理生理机制的米诺环素等药物可以重新用于治疗这种改变生活的并发症SCD 的。