Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Sci Adv. 2023 Mar 29;9(13):eade9931. doi: 10.1126/sciadv.ade9931.
Following peripheral nerve injury, extracellular adenosine 5'-triphosphate (ATP)-mediated purinergic signaling is crucial for spinal cord microglia activation and neuropathic pain. However, the mechanisms of ATP release remain poorly understood. Here, we show that volume-regulated anion channel (VRAC) is an ATP-releasing channel and is activated by inflammatory mediator sphingosine-1-phosphate (S1P) in microglia. Mice with microglia-specific deletion of Swell1 (also known as Lrrc8a), a VRAC essential subunit, had reduced peripheral nerve injury-induced increase in extracellular ATP in spinal cord. The mutant mice also exhibited decreased spinal microgliosis, dorsal horn neuronal hyperactivity, and both evoked and spontaneous neuropathic pain-like behaviors. We further performed high-throughput screens and identified an FDA-approved drug dicumarol as a novel and potent VRAC inhibitor. Intrathecal administration of dicumarol alleviated nerve injury-induced mechanical allodynia in mice. Our findings suggest that ATP-releasing VRAC in microglia is a key spinal cord determinant of neuropathic pain and a potential therapeutic target for this debilitating disease.
在外周神经损伤后，细胞外三磷酸腺苷（ATP）介导的嘌呤能信号对于脊髓小胶质细胞的激活和神经病理性疼痛至关重要。然而，ATP 释放的机制仍知之甚少。在这里，我们表明，体积调节阴离子通道（VRAC）是一种 ATP 释放通道，并且在小胶质细胞中被炎症介质 1-磷酸鞘氨醇（S1P）激活。小胶质细胞特异性缺失 Swell1（也称为 Lrrc8a）的小鼠，其外周神经损伤诱导的脊髓中细胞外 ATP 增加减少。突变小鼠还表现出脊髓小胶质细胞增生减少、背角神经元过度兴奋以及诱发和自发的神经病理性疼痛样行为减少。我们进一步进行了高通量筛选，发现一种 FDA 批准的药物双香豆素作为一种新型强效 VRAC 抑制剂。鞘内给予双香豆素可减轻小鼠神经损伤引起的机械性痛觉过敏。我们的研究结果表明，小胶质细胞中的 ATP 释放 VRAC 是神经病理性疼痛的关键脊髓决定因素，也是这种使人衰弱的疾病的潜在治疗靶点。
