Peripherally targeted analgesia via AAV-mediated sensory neuron-specific inhibition of multiple pronociceptive sodium channels

This study reports that targeting intrinsically disordered regions of the voltage-gated sodium channel 1.7 ([Na.sub.V]1.7) protein facilitates discovery of sodium channel inhibitory peptide aptamers ([Na.sub.V]iPA) for adeno-associated virus-mediated (AAV-mediated), sensory neuron-specific analgesia. A multipronged inhibition of [I.sub.Na1.7], [I.sub.Na1.6], [I.sub.Na1.3], and [I.sub.Na1.1]--but not [I.sub.Na1.5] and [I.sub.Na1.8]--was found for a prototype and named [Na.sub.V]iPA1, which was derived from the [Na.sub.V]1.7 intracellular loop 1, and is conserved among the TTXs [Na.sub.V] subtypes. [Na.sub.V]iPA1 expression in primary sensory neurons (PSNs) of dorsal root ganglia (DRG) produced significant inhibition of TTXs [I.sub.Na] but not TTXr [I.sub.Na]. DRG injection of AAV6-encoded [Na.sub.V]iPA1 significantly attenuated evoked and spontaneous pain behaviors in both male and female rats with neuropathic pain induced by tibial nerve injury (TNI). Whole-cell current clamp of the PSNs showed that [Na.sub.V]iPA1 expression normalized PSN excitability in TNI rats, suggesting that [Na.sub.V]iPA1 attenuated pain by reversal of injury-induced neuronal hypersensitivity. IHC revealed efficient [Na.sub.V]iPA1 expression restricted in PSNs and their central and peripheral terminals, indicating PSN- restricted AAV biodistribution. Inhibition of sodium channels by [Na.sub.V]iPA1 was replicated in the human iPSC-derived sensory neurons. These results summate that [Na.sub.V]iPA1 is a promising analgesic lead that, combined with AAV-mediated PSN-specific block of multiple TTXs [Na.sub.V]s, has potential as a peripheral nerve-restricted analgesic therapeutic.
Introduction Voltage-gated sodium channels ([Na.sub.V]s) are key regulators of neuronal excitability and pain sensations (1). Mammals possess 9 isoforms of [Na.sub.V]s, of which [Na.sub.V]1.7, [Na.sub.V]1.8, and [Na.sub.V]1.9 are preferentially expressed [...]