Computer-aided Discovery of a New Nav1.7 Inhibitor for Treatment of Pain and Itch

Abstract

Background Voltage-gated sodium channel Nav1.7 has been validated as a perspective target for selective inhibitors with analgesic and anti-itch activity. The objective of this study was to discover new candidate compounds with Nav1.7 inhibitor properties. The authors hypothesized that their approach would yield at least one new compound that inhibits sodium currents in vitro and exerts analgesic and anti-itch effects in mice. Methods In silico structure-based similarity search of 1.5 million compounds followed by docking to the Nav1.7 voltage sensor of Domain 4 and molecular dynamics simulation was performed. Patch clamp experiments in Nav1.7-expressing human embryonic kidney 293 cells and in mouse and human dorsal root ganglion neurons were conducted to test sodium current inhibition. Formalin-induced inflammatory pain model, paclitaxel-induced neuropathic pain model, histamine-induced itch model, and mouse lymphoma model of chronic itch were used to confirm in vivo activity of the selected compound. Results After in silico screening, nine compounds were selected for experimental assessment in vitro. Of those, four compounds inhibited sodium currents in Nav1.7-expressing human embryonic kidney 293 cells by 29% or greater (P < 0.05). Compound 9 (3-(1-benzyl-1H-indol-3-yl)-3-(3-phenoxyphenyl)-N-(2-(pyrrolidin-1-yl)ethyl)propanamide, referred to as DA-0218) reduced sodium current by 80% with a 50% inhibition concentration of 0.74 μM (95% CI, 0.35 to 1.56 μM), but had no effects on Nav1.5-expressing human embryonic kidney 293 cells. In mouse and human dorsal root ganglion neurons, DA-0218 reduced sodium currents by 17% (95% CI, 6 to 28%) and 22% (95% CI, 9 to 35%), respectively. The inhibition was greatly potentiated in paclitaxel-treated mouse neurons. Intraperitoneal and intrathecal administration of the compound reduced formalin-induced phase II inflammatory pain behavior in mice by 76% (95% CI, 48 to 100%) and 80% (95% CI, 68 to 92%), respectively. Intrathecal administration of DA-0218 produced acute reduction in paclitaxel-induced mechanical allodynia, and inhibited histamine-induced acute itch and lymphoma-induced chronic itch. Conclusions This study’s computer-aided drug discovery approach yielded a new Nav1.7 inhibitor that shows analgesic and anti-pruritic activity in mouse models. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

FGF13 Is Required for Histamine-Induced Itch Sensation by Interaction with NaV1.7

“…Patients carrying a variant in SCN9A gene encoding Na V 1.7 experience paroxysmal itch (Devigili et al, 2014). Previous reports provide evidence in mice showing that blocking Na V 1.7 by selective antagonists inhibits the histamine-induced scratching behavior, as well as evoked neuronal excitability (Marx et al, 2016;Graceffa et al, 2017;Kornecook et al, 2017;Zhang et al, 2019;Chandra et al, 2020). First, we confirmed the role of Na V 1.7 in the histamine signaling in DRG neurons.…”

“…A recent report showed that gain-of-function mutation of Na V 1.7 caused paroxysmal itch in patients (Devigili et al, 2014). In mice, selective Na V 1.7 inhibitors suppressed itch behaviors induced by histamine (Graceffa et al, 2017;Chandra et al, 2020). Na V 1.7 KO mice in which the functional expression of Na V 1.7 being prevented in DRG and trigeminal ganglia neurons exhibited strong scratching reduction toward many pruritogens, such as C48/80, 5-HT, CQ, endothelin, and histamine (Kühn et al, 2020).…”

A new synthetic protectin D1 analog 3-oxa-PD1n-3 DPA reduces neuropathic pain and chronic itch in mice

“…on the nape of the neck under 2 % isoflurane anesthesia. 46 The scratching behavior was video recorded for 60 min using Sony HDR-CX610 camera. The video was subsequently played back offline and the number of scratches in every 60 min was counted blindly.…”

Neuro-immune interactions in paclitaxel-induced peripheral neuropathy

“…Sodium channel subunit 1.7 (Na V 1.7) [80][81][82][83][84] Increased expression in DRG and superficial SDH [81,82] and increased functionality [83,84].…”