Anti‐PD‐1 treatment protects against seizure by suppressing sodium channel function

Abstract

AbstractAimsAlthough programmed cell death protein 1 (PD‐1) typically serves as a target for immunotherapies, a few recent studies have found that PD‐1 is expressed in the nervous system and that neuronal PD‐1 might play a crucial role in regulating neuronal excitability. However, whether brain‐localized PD‐1 is involved in seizures and epileptogenesis is still unknown and worthy of in‐depth exploration.MethodsThe existence of PD‐1 in human neurons was confirmed by immunohistochemistry, and PD‐1 expression levels were measured by real‐time quantitative PCR (RT‐qPCR) and western blotting. Chemoconvulsants, pentylenetetrazol (PTZ) and cyclothiazide (CTZ), were applied for the establishment of in vivo (rodents) and in vitro (primary hippocampal neurons) models of seizure, respectively. SHR‐1210 (a PD‐1 monoclonal antibody) and sodium stibogluconate (SSG, a validated inhibitor of SH2‐containing protein tyrosine phosphatase‐1 [SHP‐1]) were administrated to investigate the impact of PD‐1 pathway blockade on epileptic behaviors of rodents and epileptiform discharges of neurons. A miRNA strategy was applied to determine the impact of PD‐1 knockdown on neuronal excitability. The electrical activities and sodium channel function of neurons were determined by whole‐cell patch‐clamp recordings. The interaction between PD‐1 and α‐6 subunit of human voltage‐gated sodium channel (Nav1.6) was validated by performing co‐immunostaining and co‐immunoprecipitation (co‐IP) experiments.ResultsOur results reveal that PD‐1 protein and mRNA levels were upregulated in lesion cores compared with perifocal tissues of surgically resected specimens from patients with intractable epilepsy. Furthermore, we show that anti‐PD‐1 treatment has anti‐seizure effects both in vivo and in vitro. Then, we reveal that PD‐1 blockade can alter the electrophysiological properties of sodium channels. Moreover, we reveal that PD‐1 acts together with downstream SHP‐1 to regulate sodium channel function and hence neuronal excitability. Further investigation suggests that there is a direct interaction between neuronal PD‐1 and Nav1.6.ConclusionOur study reveals that neuronal PD‐1 plays an important role in epilepsy and that anti‐PD‐1 treatment protects against seizures by suppressing sodium channel function, identifying anti‐PD‐1 treatment as a novel therapeutic strategy for epilepsy.