Heat shock protein 90 (Hsp90) is a ubiquitously expressed integral cellular protein essential for regulating proteomic stress. Previous research has shown that Hsp90 regulates critical signaling pathways underlying chronic pain and inflammation. Recent discovery of membrane bound ectopic Hsp90 (eHsp90) on tumor cells has shown that Hsp90 induction to the plasma membrane can stabilize disease-relevant proteins. Here, we characterize eHsp90 expression in a mouse model of inflammation and demonstrate its role in nociception and pain. We found that intraplantar complete Freund adjuvant (CFA) induced robust expression of eHsp90 on the cell membranes of primary afferent nociceptors located in the L3-L5 dorsal root ganglia (DRG), bilaterally, with minimal to no expression in other tissues. Complete Freund adjuvant–induced increases in eHsp90 expression on lumbar DRG were significantly greater in females compared with males. Furthermore, exogenous Hsp90 applied to primary Pirt-GCaMP3 nociceptors induced increases in calcium responses. Responses were estrogen-dependent such that greater activity was observed in female or estrogen-primed male nociceptors compared with unprimed male nociceptors. Treatment of mice with the selective eHsp90 inhibitor HS-131 (10 nmol) significantly reversed CFA-induced mechanical pain, thermal heat pain, and hind paw edema. Notably, a higher dose (20 nmol) of HS-131 was required to achieve analgesic and anti-inflammatory effects in females. Here, we provide the first demonstration that inflammation leads to an upregulation of eHsp90 on DRG nociceptors in a sex-dependent manner and that inhibition of eHsp90 reduces nociceptor activity, pain, and inflammation. Thus, eHsp90 represents a novel therapeutic axis for the development of gender-tailored treatments for inflammatory pain.

热休克蛋白 90 (Hsp90) 是一种普遍表达的整合细胞蛋白，对于调节蛋白质组应激至关重要。先前的研究表明，Hsp90 调节慢性疼痛和炎症的关键信号通路。最近在肿瘤细胞上发现的膜结合异位 Hsp90 (eHsp90) 表明，Hsp90 诱导到质膜上可以稳定疾病相关蛋白。在这里，我们描述了小鼠炎症模型中 eHsp90 的表达，并证明了它在伤害感受和疼痛中的作用。我们发现足底内完全弗氏佐剂 (CFA) 诱导位于 L3-L5 背根神经节 (DRG) 的双侧初级传入伤害感受器细胞膜上 eHsp90 的强烈表达，而在其他组织中表达很少或没有表达。与男性相比，完全弗氏佐剂诱导的腰椎 DRG 上 eHsp90 表达的增加在女性中显着更大。此外，将外源性 Hsp90 应用于初级 Pirt-GCaMP3 伤害感受器可诱导钙反应增加。反应是雌激素依赖性的，因此与未引发的男性伤害感受器相比，在女性或雌激素引发的男性伤害感受器中观察到更大的活性。用选择性 eHsp90 抑制剂 HS-131 (10 nmol) 治疗小鼠可显着逆转 CFA 引起的机械性疼痛、热痛和后爪水肿。值得注意的是，需要更高剂量（20 nmol）的 HS-131 才能在女性中实现镇痛和抗炎作用。在这里，我们首次证明炎症以性别依赖性方式导致 DRG 伤害感受器上 eHsp90 的上调，并且抑制 eHsp90 可减少伤害感受器活性、疼痛和炎症。因此，eHsp90 代表了开发针对性别的炎性疼痛治疗的新治疗轴。