Targeting the VEGF-A/Neuropilin 1 axis for relief of neuropathic pain.

Vascular endothelial growth factor A (VEGF-A) is a pro-nociceptive factor that causes neuronal sensitization and pain. We reported that blocking the interaction between the membrane receptor Neuropilin 1 (NRP1) and VEGF-A blocked VEGF-A mediated sensory neuron hyperexcitability and reduced mechanical hypersensitivity in a rodent chronic neuropathic pain model. These findings identified the NRP1-VEGF-A signaling axis for therapeutic targeting of chronic pain. In an in-silico screening of ∼480K small molecules binding to the extracellular b1b2 pocket of NRP1, we identified nine chemical series, with six compounds disrupting VEGF-A binding to NRP1. The small molecule with greatest efficacy, 4'-methyl-2'-morpholino-2-(phenylamino)-[4,5'-bipyrimidin]-6(1H)-one, designated NRP1-4, was selected for further evaluation. In cultured primary sensory neurons, VEGF-A enhanced excitability and decreased firing threshold, which was blocked by NRP1-4. Additionally, NaV1.7 and CaV2.2 currents, and membrane expression, were potentiated by treatment with VEGF-A and this potentiation was blocked by NRP1-4 co-treatment. NRP1-4 reduced VEGF-A-mediated increases in the frequency and amplitude of spontaneous excitatory postsynaptic currents in dorsal horn of the spinal cord. NRP1-4 did not bind to over 300 GPCRs and receptors including human opioids receptors, indicating a favorable safety profile. In rats with spared nerve injury (SNI)-induced neuropathic pain, intrathecal administration of NRP1-4 significantly attenuated mechanical allodynia. Intravenous treatment with NRP1-4 reversed both mechanical allodynia and thermal hyperalgesia in rats with L5/L6 spinal nerve ligation (SNL)-induced neuropathic pain. Collectively, our findings show that NRP1-4 is a first-in-class compound targeting the NRP1-VEGF-A signaling axis to control voltage-gated ion channel function, synaptic activity, and curb chronic pain.