K284-6111 Alleviates Memory Impairment and Neuroinflammation in Tg2576 Mice by Inhibition of Chitinase-3-like 1 Regulating ERK Dependent PTX3 Pathway

Abstract Background Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders characterized by gradual memory loss and neuropsychiatric symptoms. We have previously demonstrated that the 2-({3-[2-(1-Cyclohexen-1-yl)ethyl]-6,7-dimethoxy-4-oxo-3,4-dihydro-2-quinazolinyl}sulfanyl)-N-(4-ethylphenyl)butanamide (K284-6111), the inhibitor of CHI3L1, has an inhibitory effect on memory impairment in Αβ infusion mouse model and on LPS-induced neuroinflammation in the murine BV-2 microglia and primary cultured astrocyte. Methods In the present study, we investigated that the inhibitory effect of K284-6111 on memory dysfunction and neuroinflammation in Tg2576 transgenic mice, and more detailed correlation of CHI3L1 and AD. To investigate the effects of K284-6111 on memory dysfunction, we administered K284-6111 (3 mg/kg, p.o.) daily for four weeks to Tg2576, followed by behavioral tests of water maze test, probe test, and passive avoidance test.Results Administration of K284-6111 alleviated memory impairment in Tg2576 mice and had the effect of reducing accumulation of Aβ and neuroinflammatory responses in the mouse brain. K284-6111 treatment also selectively inactivated ERK and NF-κB pathways, which were activated when CHI3L1 was overexpressed, in mouse brain and in BV-2 cells. Web-based gene network analysis and our results of gene expression level in BV-2 cells showed that CHI3L1 is closely correlated with PTX3. Our result revealed that knockdown of PTX3 has inhibitory effect on the production of inflammatory proteins and cytokines, and on the phosphorylation of ERK and IκBα.Conclusion These results suggest that K284-6111 could improve memory dysfunction by alleviating neuroinflammation through inhibiting CHI3L1 through blocking ERK dependent PTX3 pathway.