Abstract
Purpose :
The role of claudin-5 as a key mediator of the inner Blood Retinal Barrier (iBRB) and Blood Brain Barrier (BBB) are well established. However, the role of this Tight Junction (TJ) protein in diseases affecting retinal homeostasis, remains poorly understood. In this study we analyse the effects of Claudin-5 expression disruption on Age-Related Macular Degeneration (AMD) pathology through the analysis of the immune profiles of two novel mouse models of the disease.
Methods :
The first model analysed is created through a Cldn5 flox Tie2cre system in which endothelial Cldn5 expression is heterozygosity is established. RNA samples were isolated from the retinas of these mice for qPCR analysis. Cre negative animals were used as controls.
The second model under investigation utilised AAV vectors expressing an shRNA targeting claudin-5 to decrease Cldn5 expression levels in the retinal endothelium. These mice were fed a high cholesterol diet (HCD) to further induce AMD pathogenesis. RNA samples were isolated from the RPE of these mice and subjected to a PCR array of 35 genes representing various inflammatory markers, markers of endoplasmic reticulum (ER) stress, and oxidative stress markers. Controls used were mice administered with non-targeting shRNA.
Results :
Analysis of Cldn5 tie2-cre+ retinas show a significant decrease in expression of TJ genes, Marveld2 and Lsr concomitant to Cldn5 suppression, (*p=0.048, *p=0.0493, respectively). Numerous inflammatory markers also show downregulation including Il-1β (*p=0.0455) and macrophage markers such as Tmem119 (**p=0.0089).
Results from the RPE qPCR panel show that inflammatory markers are significantly upregulated in Cldn5 deficient mice. Such markers included cytokines such as Cxcl10 (**p=0.0038), components of the complement system, Traf6, (*p=0.0197) and Toll like receptor 2 (Tlr2, **p=0.0039).
Conclusions :
The immune profile of these two disease models show trends towards two distinct inflammatory outcomes. This disparity in inflammatory phenotypes may be attributed to the synergistic effect of a HCD with decreased claudin 5 expression, resulting in the differential recruitment and activation of immune cells within the retina. Therefore, these results provide an interesting insight into the immunological implications of the disruption of claudin-5 expression in such disease contexts.
This is a 2021 ARVO Annual Meeting abstract.