Restoring Amyloid Clearance via Astrocytes: Z17 Is a Selective Inhibitor of CHI3L1 in Alzheimers Disease.

Alzheimers disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, accumulation of hallmark protein aggregates and substantial neuroinflammation. Chitinase-3-like protein 1 (CHI3L1) which is predominantly produced by activated astrocytes in the central nervous system (CNS). Overexpression of CHI3L1 has been implicated with AD progression and worsening of symptoms. Herein, we report the identification of Z17 as a novel and selective CHI3L1 inhibitor which directly bind to CHI3L1 an equilibrium dissociation constant ( KD ) of 6.0 µM. In human iPSC-derived astrocytes, Z17 acted as a dual-action regulator by reinstating astrocytic function and suppressing inflammation. Additionally, Z17 rescued CHI3L1-induced impairment by dose-dependently restoring Aβ uptake and normalizing lysosomal proteolytic activity and pH. Furthermore, Z17 effectively blocked CHI3L1-driven activation of the NF-κB pathway in human astrocytes, providing a mechanistic explanation for the functional rescue. The in vitro pharmacokinetic (PK) profiling of Z17 demonstrated favorable drug-like properties for CNS development. These findings support the advancement of Z17 as a selective CHI3L1 inhibitor capable of simultaneously mitigating neuroinflammation and restoring astrocytic clearance mechanisms, making it a highly promising therapeutic candidate for Alzheimers disease.