Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, V5Z 3N9, Canada.
Mol Neurobiol. 2019 Mar;56(3):1637-1652. doi: 10.1007/s12035-018-1192-8. Epub 2018 Jun 18.
Retinitis pigmentosa (RP) is a group of inherited neurological disorders characterized by rod photoreceptor cell death, followed by secondary cone cell death leading to progressive blindness. Currently, there are no viable treatment options for RP. Due to incomplete knowledge of the molecular signaling pathways associated with RP pathogenesis, designing therapeutic strategies remains a challenge. In particular, preventing secondary cone photoreceptor cell loss is a key goal in designing potential therapies. In this study, we identified the main drivers of rod cell death and secondary cone loss in the transgenic S334ter rhodopsin rat model, tested the efficacy of specific cell death inhibitors on retinal function, and compared the effect of combining drugs to target multiple pathways in the S334ter and P23H rhodopsin rat models. The primary driver of early rod cell death in the S334ter model was a caspase-dependent process, whereas cone cell death occurred though RIP3-dependent necroptosis. In comparison, rod cell death in the P23H model was via necroptotic signaling, whereas cone cell loss occurred through inflammasome activation. Combination therapy of four drugs worked better than the individual drugs in the P23H model but not in the S334ter model. These differences imply that treatment modalities need to be tailored for each genotype. Taken together, our data demonstrate that rationally designed genotype-specific drug combinations will be an important requisite to effectively target primary rod cell loss and more importantly secondary cone survival.
色素性视网膜炎(RP)是一组遗传性神经疾病,其特征是视杆感光细胞死亡,随后是继发的锥细胞死亡,导致进行性失明。目前,RP 没有可行的治疗选择。由于对与 RP 发病机制相关的分子信号通路了解不完整,设计治疗策略仍然是一个挑战。特别是,防止继发的锥细胞感光细胞损失是设计潜在治疗方法的关键目标。在这项研究中,我们确定了 S334ter 视蛋白转基因大鼠模型中视杆细胞死亡和继发的锥细胞损失的主要驱动因素,测试了特定细胞死亡抑制剂对视网膜功能的疗效,并比较了在 S334ter 和 P23H 视蛋白大鼠模型中联合使用药物靶向多种途径的效果。S334ter 模型中早期视杆细胞死亡的主要驱动因素是半胱天冬酶依赖性过程,而锥细胞死亡则通过 RIP3 依赖性坏死发生。相比之下,P23H 模型中的视杆细胞死亡是通过坏死信号发生的,而锥细胞损失则是通过炎症小体激活发生的。四种药物的联合治疗在 P23H 模型中的效果优于单一药物,但在 S334ter 模型中则不然。这些差异表明,治疗方式需要根据每种基因型进行调整。总之,我们的数据表明,合理设计的针对特定基因型的药物联合治疗将是有效靶向原发性视杆细胞损失和更重要的继发性锥细胞存活的重要前提。