Structure-based discovery of CZL80, a caspase-1 inhibitor with therapeutic potential for febrile seizures and later enhanced epileptogenic susceptibility

Background and purpose: Febrile seizures (FS), the most common seizures in childhood and often accompanied by later epileptogenesis, are not well controlled. Inflammatory processes have been implicated in the pathophysiology of epilepsy. However, whether Caspase-1 is involved in FS generation and could be a target for the treatment of FS is still unclear.

Experimental approach: By using pharmacological and gene intervention methods in C57BL/6J mice, we assessed the role of Caspase-1 in FS generation. We used structural virtual screening against the active site of Caspase-1, to screen compounds for druggable and safe low MW inhibitors of Caspase-1 in vitro. One compound was chosen to test in vivo for therapeutic potential, using FS models in neonatal mice and epileptogenesis in adult mice.

Key results: In mice, levels of cleaved Caspase-1 increased prior to FS onset. Caspase-1^-/- mice were resistant to FS and showed lower neuronal excitability than wild-type littermates. Conversely, overexpression of Caspase-1 using in utero electroporation increased neuronal excitability and enhanced susceptibility to FS. The structural virtual screening, using molecular docking approaches for the active site of Caspase-1 of over 1 million compounds yielded CZL80, a brain-penetrable, low MW inhibitor of Caspase-1. In neonatal mice, CZL80 markedly reduced neuronal excitability and incidence of FS generation, and, in adult mice, relieved later enhanced epileptogenic susceptibility. CZL80 was devoid of acute diazepam-like respiratory depression and chronic liver toxicity.

Conclusion and implications: Caspase-1 is essential for FS generation. CZL80 is a promising low MW inhibitor of FS and later enhanced epileptogenic susceptibility.