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Targeting ischemia-induced KCC2 hypofunction rescues refractory neonatal seizures and mitigates epileptogenesis in a
Brennan J Sullivan1, Pavel A Kipnis1, Brandon M Carter1
1Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA.
Abstract:
Neonatal seizures pose a clinical challenge in their early detection, acute management, and long-term comorbidities. They are often caused by hypoxic-ischemic encephalopathy and are frequently refractory to the first-line antiseizure medication phenobarbital. One proposed mechanism for phenobarbital inefficacy during neonatal seizures is the reduced abundance and function of the neuron-specific K+/Cl− cotransporter 2 (KCC2), which maintains chloride homeostasis and promotes GABAergic inhibition upon its phosphorylation during postnatal development. Here, we investigated whether this mechanism is causal and whether it can be rescued by KCC2 functional enhancement. In a CD-1 mouse model of refractory ischemic neonatal seizures, treatment with the KCC2 functional enhancer CLP290 rescued phenobarbital efficacy, increased KCC2 abundance, and prevented the development of epileptogenesis, as quantified by video electroencephalogram monitoring. These effects were prevented by knock-in expression of nonphosphorylatable mutants of KCC2 (S940A or T906A and T1007A), indicating that KCC2 phosphorylation regulates both neonatal seizure susceptibility and CLP290-mediated KCC2 functional enhancement. Our findings therefore validate KCC2 as a clinically relevant target for refractory neonatal seizures and provide insights for future drug development.
Insights
Neonatal seizures are hard to treat, often failing phenobarbital. Enhancing KCC2 function with CLP290 restored phenobarbital efficacy and prevented long-term seizures in a mouse model.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Epilepsy Research
Background:
- Neonatal seizures, often caused by hypoxic-ischemic encephalopathy, present significant clinical challenges.
- Refractory seizures frequently do not respond to phenobarbital, the standard first-line treatment.
- Reduced function of the K+/Cl− cotransporter 2 (KCC2) is a proposed mechanism for phenobarbital inefficacy.
Purpose of the Study:
- To investigate if impaired KCC2 function is causal in refractory neonatal seizures.
- To determine if enhancing KCC2 function can rescue phenobarbital efficacy and prevent epileptogenesis.
Main Methods:
- Utilized a CD-1 mouse model of refractory ischemic neonatal seizures.
- Administered the KCC2 functional enhancer CLP290.
- Quantified seizure activity and epileptogenesis using video electroencephalogram (EEG) monitoring.
- Employed knock-in mice expressing nonphosphorylatable KCC2 mutants (S940A or T906A and T1007A).
Main Results:
- CLP290 treatment rescued phenobarbital efficacy in refractory neonatal seizures.
- CLP290 administration increased KCC2 abundance and prevented the development of epileptogenesis.
- These beneficial effects were abrogated by knock-in expression of nonphosphorylatable KCC2 mutants.
- KCC2 phosphorylation was identified as a key regulator of neonatal seizure susceptibility and CLP290's therapeutic action.
Conclusions:
- KCC2 phosphorylation is critical for regulating neonatal seizure susceptibility.
- Enhancing KCC2 function represents a promising therapeutic strategy for refractory neonatal seizures.
- Findings validate KCC2 as a clinically relevant target and offer insights for novel drug development.
