Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA.
Center for Nanomedicine, Department of Ophthalmology, Johns Hopkins University, Baltimore, MD, USA.
Nanotheranostics. 2022 Jan 1;6(2):126-142. doi: 10.7150/ntno.63158. eCollection 2022.
Cognitive impairment is a common aspect of multiple sclerosis (MS) for which there are no treatments. Reduced brain -acetylaspartylglutamate (NAAG) levels are linked to impaired cognition in various neurological diseases, including MS. NAAG levels are regulated by glutamate carboxypeptidase II (GCPII), which hydrolyzes the neuropeptide to -acetyl-aspartate and glutamate. GCPII activity is upregulated multifold in microglia following neuroinflammation. Although several GCPII inhibitors, such as 2-PMPA, elevate brain NAAG levels and restore cognitive function in preclinical studies when given at high systemic doses or via direct brain injection, none are clinically available due to poor bioavailability and limited brain penetration. Hydroxyl-dendrimers have been successfully used to selectively deliver drugs to activated glia. We attached 2-PMPA to hydroxyl polyamidoamine (PAMAM) dendrimers (D-2PMPA) using a click chemistry approach. Cy5-labelled-D-2PMPA was used to visualize selective glial uptake and . D-2PMPA was evaluated for anti-inflammatory effects in LPS-treated glial cultures. In experimental autoimmune encephalomyelitis (EAE)-immunized mice, D-2PMPA was dosed biweekly starting at disease onset and cognition was assessed using the Barnes maze, and GCPII activity was measured in CD11b+ hippocampal cells. D-2PMPA showed preferential uptake into microglia and robust anti-inflammatory activity, including elevations in NAAG, TGFβ, and mGluR3 in glial cultures. D-2PMPA significantly improved cognition in EAE mice, even though physical severity was unaffected. GCPII activity increased >20-fold in CD11b+ cells from EAE mice, which was significantly mitigated by D-2PMPA treatment. Hydroxyl dendrimers facilitate targeted drug delivery to activated microglia. These data support further development of D-2PMPA to attenuate elevated microglial GCPII activity and treat cognitive impairment in MS.
认知障碍是多发性硬化症（MS）的一个常见特征，但目前尚无治疗方法。在包括 MS 在内的各种神经疾病中，脑内 -N-乙酰天门冬氨酸谷氨酸盐（NAAG）水平降低与认知障碍有关。NAAG 水平受谷氨酸羧肽酶 II（GCPII）调节，该酶将神经肽水解为 -N-乙酰天门冬氨酸和谷氨酸。神经炎症后，小胶质细胞中的 GCPII 活性可上调数倍。虽然几种 GCPII 抑制剂，如 2-PMPA，在高系统剂量给药或通过直接脑内注射时，可在临床前研究中升高脑内 NAAG 水平并恢复认知功能，但由于生物利用度差和脑内穿透有限，均无法在临床上应用。羟基树状聚合物已成功用于将药物选择性递送至活化的神经胶质细胞。我们使用点击化学方法将 2-PMPA 连接到羟基聚酰胺胺（PAMAM）树突（D-2PMPA）上。Cy5 标记的 D-2PMPA 用于可视化选择性神经胶质摄取和。在 LPS 处理的神经胶质细胞培养物中评估了 D-2PMPA 的抗炎作用。在实验性自身免疫性脑脊髓炎（EAE）免疫小鼠中，从疾病发作开始，每两周给予 D-2PMPA 剂量，并使用 Barnes 迷宫评估认知功能，并在 CD11b+海马细胞中测量 GCPII 活性。D-2PMPA 优先进入小胶质细胞摄取，并具有强大的抗炎活性，包括在神经胶质细胞培养物中 NAAG、TGFβ 和 mGluR3 的升高。D-2PMPA 显著改善 EAE 小鼠的认知功能，尽管身体严重程度不受影响。EAE 小鼠 CD11b+细胞中的 GCPII 活性增加了 20 多倍，D-2PMPA 治疗显著减轻了这种增加。羟基树突促进了对活化的小胶质细胞的靶向药物递送。这些数据支持进一步开发 D-2PMPA 以减轻升高的小胶质细胞 GCPII 活性并治疗 MS 中的认知障碍。
