Mutations in the rhodopsin gene may cause photoreceptor degeneration in autosomal dominant retinitis pigmentosa (ADRP) by dominant negative or toxic gain-of-function mechanisms. Controversy exists as to the mechanism by which the widely studied P23H mutation induces rod cell dysfunction and death. Inherited disease caused by dominant negative mutations may be amenable to treatment using wild-type gene augmentation. Indeed, prior studies in the RHO^P23H, Rho^+/− transgenic mouse model of ADRP have suggested that a therapeutic benefit may be achieved when wild-type rhodopsin is overexpressed following subretinal delivery of a recombinant adeno-associated viral (AAV) vector. In this study, we investigated the effect of wild-type rhodopsin supplementation on the rate of retinal degeneration in the more clinically relevant Rho^P23H/+ knock-in mouse model of ADRP. Four AAVs carrying the human rhodopsin coding sequence were first designed and compared for efficacy in the rhodopsin knockout mouse. All four vectors were capable of driving expression of the human transgene in the knockout retina with the protein being appropriately trafficked to de novo rod outer segments. The most efficient of these vectors was injected at one of two doses into the subretinal space of Rho^P23H/+ mice and the effect on retinal structure and function determined longitudinally by spectral-domain optical coherence tomography and electroretinography, respectively, over a 3-month period. Although significant overexpression of rhodopsin protein was achieved in this model, no beneficial effect on retinal structure or function was observed at either dose. Lack of therapeutic efficacy in this model may be attributable to the relative rapidity of degeneration in the Rho^P23H/+ mouse relative to the human disease, over- or under dosing at the level of individual photoreceptors, late timing of the intervention, or a possible predominant toxic gain-of-function mechanism of degeneration.

中文翻译：

---

AAV 介导的视紫质基因增强对敲入小鼠模型中显性 P23H 视紫质突变引起的视网膜变性的影响。

视紫质基因的突变可能通过显性负性或毒性功能获得机制导致常染色体显性色素性视网膜炎 (ADRP) 的光感受器变性。关于广泛研究的 P23H 突变诱导杆细胞功能障碍和死亡的机制存在争议。由显性负突变引起的遗传性疾病可能适合使用野生型基因增强进行治疗。事实上，先前对RHO ^{P23H 的}研究，Rho ^+/-ADRP 的转基因小鼠模型表明，在视网膜下递送重组腺相关病毒 (AAV) 载体后过表达野生型视紫红质时，可能会获得治疗益处。在这项研究中，我们研究了野生型视紫红质补充剂对^ADRP更具临床相关性的Rho ^P23H/+敲入小鼠模型中视网膜变性率的影响。首先设计了四种携带人视紫质编码序列的 AAV，并比较了在视紫质敲除小鼠中的功效。所有四种载体都能够在敲除视网膜中驱动人类转基因的表达，并将蛋白质适当地从头运输杆外段。这些载体中最有效的一种以两种剂量中的一种注射到Rho ^P23H/+小鼠的视网膜下空间中，并分别通过光谱域光学相干断层扫描和视网膜电图纵向确定了对视网膜结构和功能的影响，为期 3 个月时期。尽管在该模型中实现了视紫质蛋白的显着过表达，但在任一剂量下均未观察到对视网膜结构或功能的有益影响。该模型缺乏治疗效果可能是由于Rho ^P23H/+的退化速度相对^较快 与人类疾病相关的小鼠、个体光感受器水平的过量或不足、干预时间较晚或退化的可能主要毒性功能获得机制。