Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
Medical Experiment Center, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, P.R. China 712046.
Mol Pain. 2017 Jan-Dec;13:1744806917717040. doi: 10.1177/1744806917717040.
TRPV1 (transient receptor potential vanilloid subfamily member 1) is a pain signaling channel highly expressed in primary sensory neurons. Attempts for analgesia by systemic TRPV1 blockade produce undesirable side effects, such as hyperthermia and impaired heat pain sensation. One approach for TRPV1 analgesia is to target TRPV1 along the peripheral sensory pathway.
For functional blockade of TRPV1 signaling, we constructed an adeno-associated virus (AAV) vector expressing a recombinant TRPV1 interfering peptide aptamer, derived from a 38mer tetrameric assembly domain (TAD), encompassing residues 735 to 772 of rat TRPV1, fused to the C-terminus of enhanced green fluorescent protein (EGFP). AAV-targeted sensory neurons expressing EGFP-TAD after vector injection into the dorsal root ganglia (DRG) revealed decreased inward calcium current and diminished intracellular calcium accumulation in response to capsaicin, compared to neurons of naïve or expressing EGFP alone. To examine the potential for treating neuropathic pain, AAV-EGFP-TAD was injected into fourth and fifth lumbar (L) DRGs of rats subjected to neuropathic pain by tibial nerve injury (TNI). Results showed that AAV-directed selective expression of EGFP-TAD in L4/L5 DRG neuron somata, and their peripheral and central axonal projections can limit TNI-induced neuropathic pain behavior, including hypersensitivity to heat and, to a less extent, mechanical stimulation.
Selective inhibition of TRPV1 activity in primary sensory neurons by DRG delivery of AAV-encoded analgesic interfering peptide aptamers is efficacious in attenuation of neuropathic pain. With further improvements of vector constructs and in vivo application, this approach might have the potential to develop as an alternative gene therapy strategy to treat chronic pain, especially heat hypersensitivity, without complications due to systemic TRPV1 blockade.
TRPV1（瞬时受体电位香草素亚家族成员 1）是一种在初级感觉神经元中高度表达的疼痛信号通道。全身性 TRPV1 阻断的镇痛尝试会产生不良的副作用，如体温升高和热痛感觉受损。TRPV1 镇痛的一种方法是靶向沿外周感觉途径的 TRPV1。
为了功能性阻断 TRPV1 信号，我们构建了一种表达重组 TRPV1 干扰肽适体的腺相关病毒（AAV）载体，该适体源自包含大鼠 TRPV1 735 至 772 位残基的四聚体组装结构域（TAD）的 38 mer 片段，融合到增强型绿色荧光蛋白（EGFP）的 C 末端。将 AAV 靶向感觉神经元注入背根神经节（DRG）后，与表达 EGFP 或 EGFP-TAD 的神经元相比，发现它们的内向钙电流减少，对辣椒素的细胞内钙积累减少。为了研究治疗神经病理性疼痛的潜力，将 AAV-EGFP-TAD 注入由胫骨神经损伤（TNI）引起的神经病理性疼痛大鼠的第四和第五腰椎（L）DRG。结果表明，AAV 引导的 EGFP-TAD 在 L4/L5 DRG 神经元胞体中的选择性表达，以及它们的外周和中枢轴突投射，可以限制 TNI 诱导的神经病理性疼痛行为，包括对热的超敏反应，以及在较小程度上对机械刺激的超敏反应。
通过 DRG 递送 AAV 编码的镇痛干扰肽适体选择性抑制初级感觉神经元中的 TRPV1 活性，可有效减轻神经病理性疼痛。通过进一步改进载体构建和体内应用，这种方法有可能发展成为治疗慢性疼痛的替代基因治疗策略，特别是治疗热敏感性疼痛，而不会因全身性 TRPV1 阻断而产生并发症。
