P2X7 receptor antagonism suppresses epileptiform-like activity in an
inflammation-primed human iPSC-derived neuron model of drug-resistant
epilepsy
Abstract
Background and Purpose Neuroinflammation is increasingly recognized to
contribute to drug-resistant epilepsy. Activation of the ATP-gated P2X7
receptor (P2X7R) has emerged as an important upstream mechanism and
increased P2X7R expression is present in the seizure focus in rodent
models and patients. Pharmacologic antagonism of the P2X7R can attenuate
seizures in rodents but this has not been explored in human neuronal
networks. Experimental Approach Human neurons were differentiated from
two induced pluripotent stem cell (hiPSC) lines. P2X7R function on
neurons was assessed via P2X7R agonist BzATP-evoked calcium transients.
Acute or chronic in vitro models of epileptiform-like events were
generated by exposure of hiPSC cultures to the GABAA receptor antagonist
picrotoxin or a cocktail of picrotoxin and neuroinflammatory agents with
or without the presence of P2X7R antagonists. Epileptiform-like activity
was measured via single cell patch-clamp recordings. Key Results BzATP
application (300 µM) resulted in increased calcium influx in
hiPSC-derived neurons which was blocked by the P2X7R antagonists
JNJ-47965567 (100 nM) and AFC-5128 (30 nM). Single-cell patch-clamp
recordings showed that, while treatment with AFC-5128 did not reduce
epileptiform-like activity triggered by picrotoxin alone, AFC-5128
reduced the severity of epileptiform-like activity under inflammatory
conditions. Notably, epileptiform-like events in the inflammation-primed
picrotoxin model were refractory to the anti-seizure medication
carbamazepine alone but were reduced by the co-application of
carbamazepine with AFC-5128. Conclusion and Implications Our findings
demonstrate anti-seizure effects of targeting the P2X7R in a human
neuronal network model of epilepsy and suggest P2X7R-based treatments
may be an effective add-on therapy for controlling drug-resistant
seizures.