Abstract
Purpose :
Cystoid edema (CE) is associated with blood-retina-barrier (BRB) breakdown and an abnormal distribution and activity of carbonic anhydrase (CA) on retinal pigment epithelium (RPE) cells. Treatment with carbonic anhydrase inhibitors (CAI) is often used, especially for CE in the context of retinitis pigmentosa. Recognizing the generally low efficacy of CAI treatment, our goal is to study new CE medicines in a mouse model. We hypothesized that the transgenic Norrie disease protein (NDP) knockout (KO) mouse, which displays CE, will have increased apical RPE (aRPE) CAXIV compared to wild type (WT). We expect this compensatory expression change to mimic the effect of CAXIV inhibition by CAIs on the basolateral RPE.
Methods :
Retinal cryosections (18um) of 2.5-months-old KO mice were stained with anti-CAXIV (Invitrogen) antibody and compared to age-matched WT littermates. A Zeiss LSM710 confocal microscope was used for image acquisition with identical settings per sample. ImageJ was used to quantify mean fluorescence signal within regions of interest (ROI) outlining aRPE or neurosensory retina (NR). We included 2 WT mice and 3 KO mice with 13 and 16 retinal sections respectively. An unpaired t-test was used to compare WT and KO groups for NR and aRPE fluorescence.
Results :
The WT aRPE showed increased mean fluorescence intensity compared to the KO aRPE (9.540 vs 7.885, p=0.3522). The WT NR had increased mean fluorescence intensity compared to the KO retina (17.48 vs 14.13, p= 0.0902).
Conclusions :
These preliminary findings suggest decreased CAXIV expression in the aRPE and NR in a murine model of a disease with CE resulting from inner BRB breakdown. The results do not support our hypothesis and instead show a trend that suggests CAXIV downregulation in the NDP KO mouse retina and aRPE. Further quantification and analysis of this difference can help elucidate the mechanism by which CAIs decrease CE in diseases of inner BRB breakdown.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.