Dysregulated claudin-5 cycling in the inner retina causes retinal pigment epithelial cell atrophy
Natalie Hudson, Lucia Celkova, Alan Hopkins, Chris Greene, Federica Storti, Ema Ozaki, Erin Fahey, Sofia Theodoropoulou, Paul F. Kenna, Marian M. Humphries, Annie M. Curtis, Eleanor Demmons, Akeem Browne, Shervin Liddie, Matthew S. Lawrence, Christian Grimm, Mark T. Cahill, Pete Humphries, Sarah L. Doyle, Matthew Campbell
Natalie Hudson, Lucia Celkova, Alan Hopkins, Chris Greene, Federica Storti, Ema Ozaki, Erin Fahey, Sofia Theodoropoulou, Paul F. Kenna, Marian M. Humphries, Annie M. Curtis, Eleanor Demmons, Akeem Browne, Shervin Liddie, Matthew S. Lawrence, Christian Grimm, Mark T. Cahill, Pete Humphries, Sarah L. Doyle, Matthew Campbell
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Research Article Ophthalmology Vascular biology

Dysregulated claudin-5 cycling in the inner retina causes retinal pigment epithelial cell atrophy

Abstract

Age-related macular degeneration (AMD) is the leading cause of central retinal vision loss worldwide, with an estimated 1 in 10 people over the age of 55 showing early signs of the condition. There are currently no forms of therapy available for the end stage of dry AMD, geographic atrophy (GA). Here, we show that the inner blood-retina barrier (iBRB) is highly dynamic and may play a contributory role in GA development. We have discovered that the gene CLDN5, which encodes claudin-5, a tight junction protein abundantly expressed at the iBRB, is regulated by BMAL1 and the circadian clock. Persistent suppression of claudin-5 expression in mice exposed to a cholesterol-enriched diet induced striking retinal pigment epithelium (RPE) cell atrophy, and persistent targeted suppression of claudin-5 in the macular region of nonhuman primates induced RPE cell atrophy. Moreover, fundus fluorescein angiography in human and nonhuman primate subjects showed increased retinal vascular permeability in the evening compared with the morning. These findings implicate an inner retina–derived component in the early pathophysiological changes observed in AMD, and we suggest that restoring the integrity of the iBRB may represent a novel therapeutic target for the prevention and treatment of GA secondary to dry AMD.

Authors

Natalie Hudson, Lucia Celkova, Alan Hopkins, Chris Greene, Federica Storti, Ema Ozaki, Erin Fahey, Sofia Theodoropoulou, Paul F. Kenna, Marian M. Humphries, Annie M. Curtis, Eleanor Demmons, Akeem Browne, Shervin Liddie, Matthew S. Lawrence, Christian Grimm, Mark T. Cahill, Pete Humphries, Sarah L. Doyle, Matthew Campbell

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Figure 4

Persistent claudin-5 suppression induces RPE cell atrophy.

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Persistent claudin-5 suppression induces RPE cell atrophy. (A) FFA in mi...
(A) FFA in mice injected with an NT shRNA AAV2/9 and fed a normal diet (ND) (top left), or HCD (bottom left). FFA analysis of mice injected subretinally with a Cldn5-targeting shRNA AAV2/9 and fed an ND (top right) or an HCD (bottom right) (n = 12 mice per group). (B) Retinal histology of mouse injected subretinally with an NT shRNA AAV2/9 and fed an HCD (left) or claudin-5–targeting shRNA AAV2/9 and fed an HCD (right). Blue, DAPI; red, autofluorescence. (C) Semithin sections of mice injected with NT AAV or claudin-5 AAV and fed an HCD. (D) ZO-1 (green) staining in flat mounts of mice receiving AAV2/9.NTshRNA subretinally (left) or AAV2/9.CL5shRNA (right). (Images representative of n = 12 mice per group.) (E) Schematic representation of retinal interstitial kinesis. Normal paracellular flux of blood-derived components toward the RPE (left). Aberrant flux of material from the inner retina inducing RPE atrophy. (F) FFA analysis in Cldn5 Tie2-Cre− mice (left). FFA analysis in Cldn5 Tie2-Cre+ mice (right). Quantitative analysis of fluorescein leakage in Cldn5 Tie2-Cre+ mice (***P < 0.001, n = 7 mice for Cldn5 Tie2-Cre−, and n = 8 mice for Cldn5 Tie-Cre+). (G) Claudin-5 (red) expression in Cldn5 Tie2-Cre− mice (left) compared with Cldn5.Tie2-Cre+ mice (right). Green, IB4. (H) Retinal histology in Cldn5 Tie2-Cre− mice fed an HCD (left) compared with Cldn5 Tie2-Cre+ mice fed an HCD (right). (n = 7 mice.) Blue, DAPI. Student’s t test was used, with significance represented by a P value of less than 0.05. ANOVA was used with Bonferroni’s post hoc test and significance represented by a P value of less than or equal to 0.05. Original magnification, ×40 (B–D, G, and H).