Patel Sugandha, Dobrowsky Rick T
Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas 66045, United States.
ACS Pharmacol Transl Sci. 2025 Mar 12;8(4):1129-1139. doi: 10.1021/acsptsci.5c00021. eCollection 2025 Apr 11.
Diabetic peripheral neuropathy (DPN) is a common complication of diabetes arising in part from glycemic damage to neurons and Schwann cells (SC). While the pathogenic mechanisms of DPN are complex, mitochondrial dysfunction and endoplasmic reticulum (ER) stress contribute to the development of DPN and serve as therapeutic targets for disease modification. Cemdomespib is an orally bioavailable small molecule which alleviates clinical indices of DPN that correlate with improvements in neuronal oxidative stress and mitochondrial bioenergetics. However, the contribution of SC ER stress in the onset of DPN and the therapeutic efficacy of cemdomespib remains unknown. To address this issue, mice expressing a conditional deletion of protein kinase RNA-like ER kinase (PERK) in myelinating SCs (SC-cPERK KO) and control SC-PERK mice were rendered diabetic with streptozotocin. Diabetic SC-PERK and SC-cPERK KO mice developed a similar magnitude of DPN as quantified by the onset of a thermal/mechanical hypoalgesia, decreases in nerve conduction velocity (NCV) and intraepidermal fiber density (iENFD). After 8 weeks of diabetes, daily treatment with 1 mg/kg cemdomespib for an additional 8 weeks significantly improved thermal/mechanical hypoalgesia, NCV, iENFD and decreased markers of ER stress in diabetic SC-PERK mice, but the drug had no effect in diabetic SC-cPERK KO mice. Nrf2 is a PERK substrate and studies using rat SCs subjected to ER stress demonstrated that cemdomespib increased Nrf2 activity. Collectively, these data suggest that activation of SC PERK by diabetes is not necessary for the onset of DPN, but serves as a target in the action of cemdomespib, potentially by increasing Nrf2 activity.
糖尿病性周围神经病变(DPN)是糖尿病常见的并发症,部分原因是血糖对神经元和施万细胞(SC)造成损害。虽然DPN的致病机制复杂,但线粒体功能障碍和内质网(ER)应激促使DPN发生,并成为疾病改善的治疗靶点。塞姆多司匹布是一种口服生物利用度高的小分子药物,可改善与神经元氧化应激和线粒体生物能量学改善相关的DPN临床指标。然而,SC内质网应激在DPN发病中的作用以及塞姆多司匹布的治疗效果仍不清楚。为解决这一问题,通过链脲佐菌素使在有髓鞘SC中表达条件性缺失蛋白激酶RNA样内质网激酶(PERK)的小鼠(SC-cPERK KO)和对照SC-PERK小鼠患糖尿病。糖尿病SC-PERK和SC-cPERK KO小鼠出现了相似程度的DPN,通过热/机械性痛觉减退的发生、神经传导速度(NCV)和表皮内纤维密度(iENFD)的降低来量化。糖尿病8周后,每天用1mg/kg塞姆多司匹布再治疗8周,可显著改善糖尿病SC-PERK小鼠的热/机械性痛觉减退、NCV、iENFD,并降低内质网应激标志物,但该药物对糖尿病SC-cPERK KO小鼠无效。Nrf2是PERK的底物,对遭受内质网应激的大鼠SCs的研究表明,塞姆多司匹布可增加Nrf2活性。总体而言,这些数据表明,糖尿病激活SC PERK对DPN的发病并非必要,但可能通过增加Nrf2活性,成为塞姆多司匹布作用的靶点。