PRPH2-associated alterations in retinal function and morphology involve inflammatory responses in a CRISPR-generated mouse model

Abstract

Purpose : A broad range of inherited retinal diseases, including central areolar choroidal dystrophy (CACD), is associated with mutations in the PRPH2 gene. Here we aimed to characterize a mouse model with p.Arg195Leu mutation in the PRPH2 gene, previously described in human patients.

Methods : Appling the CRISPR/Cas9 system to insert the Arg195Leu mutation, we generated Prph2^WT/KI and Prph2^KI/KImice models. To characterize both models at different time points, we analyzed retinal function by electroretinography and optomotor test. The structural integrity and the morphology of the retina were studied using optical coherence tomography (OCT), immunohistochemistry, and TEM images. Additionally, we used flow cytometry to evaluate the inflammatory state of the retina.

Results : A progressive retinal degeneration was found affecting both Prph2^WT/KI and Prph2^KI/KI mice models. Significantly decreased retinal function from 3 months of age in Prph2^KI/KI and 6 months of age in Prph2^WT/KIwas correlated with progressive degeneration of the outer nuclear layer shown by OCT images. Using specific markers, we found unstructured and shortened photoreceptor outer segments. Moreover, TEM images confirmed an abnormal stacking and alignment of photoreceptor discs. Furthermore, retinal degeneration found in both mice models was associated with an increased inflammatory state of the retina. Flow cytometry analyses showed an increased CD11b+CD11c^hiMHCII+ population over time.

Conclusions : Prph2^WT/KI and Prph2^KI/KI mice models showed progressive retinal degeneration and aberrant formation of photoreceptor outer segments, displaying a similar pattern to that found in patients with the same retinal dystrophy. Thus, this mice model can be suitable for further CACD characterization and evaluation of different therapeutic strategies.

Support: Spanish Ministry of Science and Innovation (FEDER-PID2019-106230RB-I00), Spanish Ministry of Universities (FPU18/02964), National Institute of Health Carlos III (RETICS-FEDER-RD16/0008/0016), Generalitat Valenciana (IDIFEDER/2017/064, PROMETEO/2021/024, ACIF/2020/203) and University of Alicante (MARSALAS21-35).

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.