Intraarticular Adeno‐Associated Virus Serotype AAV‐PHP.S–Mediated Chemogenetic Targeting of Knee‐Innervating Dorsal Root Ganglion Neurons Alleviates Inflammatory Pain in Mice

Abstract

Objective. Joint pain is the major clinical symptom of arthritis that affects millions of people. Controlling the excitability of knee-innervating dorsal root ganglion (DRG) neurons (knee neurons) could potentially provide pain relief. We undertook this study to evaluate whether the newly engineered adeno-associated virus (AAV) serotype, AAV-PHP.S, can deliver functional artificial receptors to control knee neuron excitability following intraarticular knee injection. Methods. The AAV-PHP.S virus, packaged with dTomato fluorescent protein and either excitatory (G q) or inhibitory (G i) designer receptors exclusively activated by designer drugs (DREADDs), was injected into the knee joints of adult mice. Labeling of DRG neurons with AAV-PHP.S from the knee was evaluated using immunohistochemistry. The functionality of G q-and G i-DREADDs was evaluated using whole-cell patch clamp electrophysiology on acutely cultured DRG neurons. Pain behavior in mice was assessed using a digging assay, dynamic weight bearing, and rotarod performance, before and after intraperitoneal administration of the DREADD activator, Compound 21. Results. We showed that AAV-PHP.S can deliver functional genes into ~7% of lumbar DRG neurons when injected into the knee joint in a similar manner to the well-established retrograde tracer, fast blue. Short-term activation of AAV-PHP.S-delivered G q-DREADD increased excitability of knee neurons in vitro (P = 0.02 by unpaired t-test), without inducing overt pain in mice when activated in vivo. By contrast, in vivo G i-DREADD activation alleviated digging deficits induced by Freund's complete adjuvant-mediated knee inflammation (P = 0.0002 by repeated-measures analysis of variance [ANOVA] followed by Holm-Sidak multiple comparisons test). A concomitant decrease in knee neuron excitability was observed in vitro (P = 0.005 by ANOVA followed by Holm-Sidak multiple comparisons test). Conclusion. We describe an AAV-mediated chemogenetic approach to specifically control joint pain, which may be utilized in translational arthritic pain research.

Efficacy of AAV serotypes to target Schwann cells after intrathecal and intravenous delivery

“…AAVrh10 was also shown to be more efficient in transducing different cell types of the CNS, although it remained close to the efficiency of AAV9 34 – 36 . Although previous studies suggested that PHP-S may be a suitable vector to target the PNS 30 , 37 , in our hands it did not provide any advantage compared to AAV9 or AAVrh10 serotypes at least for Schwann cell targeting, although it appears to adequately target DRGs.…”

Human Labor Pain Is Influenced by the Voltage-Gated Potassium Channel KV6.4 Subunit

“…Article ll OPEN ACCESS herein demonstrate the effect of K V 6.4-Met419 on neuronal excitability, another way to demonstrate this would be to generate transgenic mice or use adeno-associated viruses to transduce sensory neurons innervating a specific target, as conducted recently with the knee (Chakrabarti et al, 2020). Using mice overexpressing K V 6.4-Met419, we hypothesize that, like humans expressing the SNP rs140124801 rare allele, these K V 6.4-Met419 mice might have a raised threshold to acute noxious stimuli compared with wild-type mice and potentially have a reduced chronic pain phenotype, results that would align with the known roles of K V channels in mouse pain behavior; for example, knockout of K V 9.1 leads to increased basal mechanical pain and exacerbates neuropathic pain (Tsantoulas et al, 2018).…”

Human mesenchymal stem cells and derived extracellular vesicles reduce sensory neuron hyperexcitability and pain-related behaviors in a mouse model of osteoarthritis

“…Sensory neuron sensitization is known to underlie the pain-related behavioral changes that occur in rat OA ( 56 ) and sensory neuron hyperexcitability is also common to mouse and sheep models of joint pain ( 13 , 41 , 57 ). Thus, we performed electrophysiological characterization of retrograde labelled, knee-innervating neurons and observed depolarization of the RMP and lowering of the AP threshold in knee-innervating neurons isolated from DMM mice compared to those isolated from sham mice, effects that were not observed in neurons isolated from DMM mice treated with MSCs or MSC-EVs (Fig.…”

“…Peripheral input is a major contributor to OA pain as demonstrated by reduced pain in OA patients following: i) intra-articular injections of the local anesthetic lidocaine ( 9 ), ii) a peripherally restricted anti-nerve growth factor (NGF) antibody ( 10 ) and iii) total knee replacement (although pain persists in some patients) ( 11 ). Moreover, in rodents, inhibition of nociceptor activity with the quaternary anesthetic QX-314 ameliorated early OA pain ( 12 ), and we have previously shown that pain behaviors following joint injury can be reversed through chemogenetic inhibition of knee-innervating sensory neurons ( 13 ). Furthermore, in the monoiodoacetate model of OA in rats, it has been shown that knee-innervating extracellular electrophysiological recordings become sensitized early after disease onset (from day 3) and that this is maintained, whereas bone-innervating afferents only become sensitized late in disease (day 28) ( 14 ).…”