NXP032 Improves Memory Impairment Through Suppression of Tauopathy in PS19 Mice and Attenuates Okadaic Acid-Induced Tauopathy in SH-SY5Y Cells

Tauopathy is widely observed in multiple neurodegenerative diseases such as Alzheimer’s disease (AD) and characterized by abnormal tau protein phosphorylation, aggregation and its accumulation as a form of neurofibrillary tangle (NFT) in the brain. However, there are no effective treatments targeting tau pathology in the AD. Vitamin C is known to reduce tauopathy and modulate one of its regulators called glycogen synthase kinase 3 (GSK3) in the body. Nevertheless, vitamin C has a limitation of its stability during metabolism due to its chemical properties. Thus, in the current study, NXP032 (a vitamin C/aptamer complex) was tested as a candidate for tau-targeting treatment because it can preserve antioxidative efficacy of vitamin C before it can reach the target tissue. In this context, the current study aimed to investigate the therapeutic effect of NXP032 on tauopathy in vivo and in vitro. As a result, NXP032 attenuated cognitive and memory decline and reduced NFT and tau hyperphosphorylation in the P301S mutant human tau transgenic mice (or called PS19 mice). In addition, NXP032 suppressed neuroinflammation found in the PS19 mice. Furthermore, NXP032 protected SH-SY5Y human neuroblastoma cells from okadaic acid (OKA)-induced cytotoxicity. Especially, 10 ng/ml of NXP032 reduced tau hyperphosphorylation and GSK3 activation though its phosphorylation at Tyr216 site which were promoted by OKA treatment in the SH-SY5Y cells. Taken together, our results suggest that NXP032 might be a potential therapy for AD and tauopathy-related neurodegenerative disorders as well.