ATP mediates neuropathic pain in neuromyelitis optica via microglial activation

Abstract Background Intractable neuropathic pain is a common symptom of neuromyelitis optica spectrum disorder (NMOSD). However, the underlying mechanism of NMOSD pain remains to be elucidated. The aim of this study was to establish a novel animal model of NMOSD pain and to investigate its pathogenic mechanism. Methods We established an NMOSD pain model by injecting anti-AQP4 recombinant autoantibodies (AQP4-Ab) from NMOSD patient plasmablasts into rat spinal cords. We performed transcriptome analysis and pharmacological inhibition to elucidate the core mechanism of allodynia in the model. Results Development of mechanical allodynia was confirmed in the NMOSD pain model. AQP4-Ab mediated extracellular ATP release in vitro, and pharmacological inhibition of ATP receptor reversed mechanical allodynia in the NMOSD pain model. Furthermore, transcriptome analysis revealed microglial activation and elevated levels of IL-1β in NMOSD spinal cord. Inhibition of microglial activation and neutralization of IL-1β also attenuated neuropathic pain in the NMOSD rat model. In human patients, CSF ATP concentration was significantly higher in the acute and remission phase of NMOSD than in multiple sclerosis or other neurological disorders. Conclusion A novel NMOSD pain model was established. ATP, microglial activation, and IL-1β secretion orchestrate the pathogenesis of NMOSD neuropathic pain.