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Previous studies have revealed that norrin can reverse vascular endothelial-growth-factor (VEGF)-induced permeability in a ß-catenin-dependent pathway. Here, we have explored the contribution of disheveled-1 (DVL1) in norrin-induced blood-retinal barrier (BRB) restoration. We provide evidence that in addition to canonical signaling, DVL1 promotes tight junction (TJ) stabilization through a novel, non-canonical signaling pathway involving direct claudin-5 (CLDN5) binding. Immunofluorescence staining of rat retinal cross-sections showed enriched expression of DVL1 and 3 at endothelial capillaries and co-localization with CLDN5 and ZO-1 at the TJ complex in primary bovine retinal endothelial cells (BRECs). Barrier properties of BRECs were determined via measurements of trans-endothelial electrical resistance (TEER) or permeability to 70 kDa RITC-dextran. These studies demonstrated that norrin restoration of barrier properties after VEGF treatment required DVL1 as an siRNA knockdown of Dvl1 but not Dvl2 or Dvl3, reduced basal barrier properties and ablated norrin-induced barrier restoration. However, loss of Dvl1 did not decrease ß-catenin signaling activity as measured by Axin2 mRNA expression, suggesting the contribution of a non-canonical pathway. DVL and TJ protein interactions were analyzed via co-immunoprecipitation of endogenous protein in BRECs, which demonstrated that DVL1 interacts with both CLDN5 and ZO-1, while DVL3 interacts only with ZO-1. These interactions were most abundant after inducing BRB restoration by treating BRECs with VEGF and norrin. DVL has previously been shown to form intramolecular bindings between the C-terminal PDZ-binding motif (PDZ-BM) with an internal PDZ domain. Co-transfection of HEK293 cells with DVL1 and CLDN5 or relevant mutants revealed that DVL1 interacts with CLDN5 through the DVL PDZ domain binding, CLDN5 PDZ-BM, in competition with DVL1 PDZ-BM, since DVL/CLDN5 interaction increases with deletion of the DVL1 PDZ-BM and decreases by co-expressing the C-terminal fragment of DVL1 containing the PDZ-BM or through deletion of CLDN5 PDZ-BM. In BREC cells, transfection of the C-terminal fragment of DVL1 downregulates the expression of CLDN5 but does not affect the expression of other proteins of the TJs, including ZO-1, occludin, CLDN1 or VE-cadherin. Blocking DVL1/CLDN5 interaction increased basal permeability and prevented norrin induction of barrier properties after VEGF. Combined with previous data, these results demonstrate that norrin signals through both a canonical ß-catenin pathway and a non-canonical signaling pathway by which DVL1 directly binds to CLDN5 to promote barrier properties.

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The chronic complications of diabetes mellitus constitute a major public health problem. For example, diabetic eye diseases are the most important cause of blindness, and diabetic nephropathy is the most frequent cause of chronic kidney disease worldwide. The cellular and molecular mechanisms of these chronic complications are still poorly understood, preventing the development of effective treatment strategies. Tight junctions (TJs) are epithelial intercellular junctions located at the most apical region of cell-cell contacts, and their main function is to restrict the passage of molecules through the paracellular space. The TJs consist of over 40 proteins, and the most important are occludin, claudins and the zonula occludens. Accumulating evidence suggests that TJ disruption in different organs, such as the brain, nerves, retina and kidneys, plays a fundamental pathophysiological role in the development of chronic complications. Increased permeability of the blood-brain barrier and the blood-retinal barrier has been demonstrated in diabetic neuropathy, brain injury and diabetic retinopathy. The consequences of TJ disruption on kidney function or progression of kidney disease are currently unknown. In the present review, we highlighted the molecular events that lead to barrier dysfunction in diabetes. Further investigation of the mechanisms underlying TJ disruption is expected to provide new insights into therapeutic approaches to ameliorate the chronic complications of diabetes mellitus.

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Diabetic macular edema (DME) is the most common cause of vision loss in diabetic eyes, and due to the rapid rise in the number of diabetic patients, the treatment burden has increased exponentially. The introduction of antivascular endothelial growth factor (anti-VEGF) therapy has been a major breakthrough in the management of center-involving DME, replacing laser photocoagulation as the first-line treatment. Despite the improvement in DME treatment with anti-VEGF therapy, persistent DME remains a challenge due to the extremely complex pathogenesis and the involvement of several different biochemical pathways. This review focuses on therapeutic options for persistent DME, which include corticosteroids, laser, and surgery. Novel agents for DME control such as new anti-VEGF, interleukin inhibitor, Rho-kinase inhibitor, and neuroprotective agents that are being investigated are reviewed as well. Future treatment perspectives include an individualized DME management.

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ABSTRACT A 26-year-old woman presented at 28 weeks gestation with hypertensive choroidopathy associated with pre-eclampsia. Fundus photography, fundus autofluorescence, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography, and indocyanine green angiography were performed in both eyes in the immediate postoperative period. SD-OCT images were obtained before delivery and during a 3-month follow-up. Fundus autofluorescence exhibited patchy hyper- and hypoautofluorescent lesions; fluorescein and indocyanine green angiography revealed areas of choroidal ischemia; and SD-OCT showed disorganization of the outer retinal layers and disruption of the ellipsoid zone. After her blood pressure was stabilized, progressive recovery of the outer retinal layer was monitored on SD-OCT.

RESUMO Uma mulher de 26 anos de idade, com 28 semanas de gestação apresentando coroidopatia hipertensiva associada à pré-eclâmpsia. Retinografia, autofluorescência, tomografia de coerência óptica de domínio espectral, angiofluoresceínografia e angiografia com indocianina verde foram realizadas em ambos os olhos no período pós-operatório imediato do parto. Imagens da tomografia de coerência óptica de domínio espectral foram obtidas antes do parto e durante o seguimento de 3 meses. A autofluorescência apresentou lesões heterogêneas hiper e hipoautofluorescentes, a angiofluoresceínografia e angiografia com indocianina verde revelaram áreas de isquemia de coroide, e a tomografia de coerência óptica de domínio espectral apresentou desorganização das camadas externas da retina e interrupção da zona elipsóide. Após a estabilização da pressão sanguínea, a recuperação progressiva da camada externa da retina foi monitorada pela tomografia de coerência óptica de domínio espectral.

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ABSTRACT Purpose: To evaluate the efficacy of prostaglandin antagonists on blood-retinal barrier breakdown induced by anterior segment intraocular simulated surgery. Methods: Rats were randomly assigned to a negative control group, model group, nonsteroidal anti-inflammatory drugs prophylactic treatment group, nonsteroidal anti-inflammatory drugs treatment group, corticosteroid prophylactic treatment group, and corticosteroid treatment group. Four hours and 48h after modeling, the concentrations of PGE1, PGE2, and PGF2 α in the aqueous humor and vitreous body of the rat model were visualized using ELISA. The integrity of the blood-retinal barrier was quantitatively measured using Evan's blue as a tracer. Results: Four hours after modeling, the concentrations of PGE1, PGE2, and PGF2α in the aqueous humor and vitreous body in the negative control group and the nonsteroidal anti-inflammatory drugs prophylactic treatment group were significantly lower than those in the model group. The concentrations of PGE1, PGE2, and PGF2α in the aqueous humor and vitreous body in the corticosteroid prophylactic treatment group were higher than those in the negative control group and the nonsteroidal anti-inflammatory drugs prophylactic treatment group. Forty-eight hours after modeling, the concentrations of PGE1, PGE2, and PGF2α in the aqueous humor and vitreous body in the nonsteroidal anti-inflammatory drugs prophylactic treatment group, nonsteroidal anti-inflammatory drugs treatment group, corticosteroid prophylactic treatment group, and corticosteroid treatment group were lower than those in the model group, but higher than those in the negative group. Retinal Evan's blue leakage in the nonsteroidal anti-inflammatory drugs prophylactic treatment group was higher than that in the negative control group, and lower than those in the nonsteroidal anti-inflammatory drugs treatment group, corticosteroid prophylactic treatment group, corticosteroid treatment group, and model group. Retinal Evan's blue leakage in the nonsteroidal anti-inflammatory drugs treatment group, corticosteroid prophylactic treatment group, and corticosteroid treatment group were lower than those in the model group. Conclusions: This study confirms that prostaglandin antagonists can relieve blood-retinal barrier breakdown in a rat model and that nonsteroidal anti-inflammatory drugs prophylactic treatment can achieve better efficacy.

RESUMO Objetivos: Avaliar a eficácia do antagonista de prostaglandinas no rompimento da barreira hemato-retiniana induzida por cirurgia simulada intraocular do segmento anterior. Métodos: Os ratos foram divididos aleatoriamente em grupo controle negativo, grupo modelo, grupo de tratamento profilático com drogas anti-inflamatórias não esteroides, grupo de tratamento com anti-inflamatórias não esteroides, grupo de tratamento profilático com corticosteroides e grupo de tratamento com corticosteroides. Quatro e 48h após a modelagem, as concentrações de PGE1, PGE2 e PGF2 α no humor aquoso e no corpo vítreo em modelo em ratos foram detectadas através de Elisa. A integridade da barreira hemato-retiniana foi quantitativamente mensurada utilizando o azul de Evans como marcador. Resultados: Quatro horas após a modelagem, as concentrações de PGE1, PGE2 e PGF2α no humor aquoso e no corpo vítreo no grupo controle negativo e no grupo de tratamento profilático com anti-inflamatórias não esteroides foram significativamente menores do que as do grupo modelo. As concentrações de PGE1, PGE2 e PGF2α no humor aquoso e no corpo vítreo no grupo de tratamento profilático com corticosteroides foram maiores do que as observadas no grupo controle negativo e no grupo de tratamento profilático com anti-inflamatórias não esteroides. 48h após a modelagem, as concentrações de PGE1, PGE2 e PGF2α no humor aquoso e no corpo vítreo no grupo de tratamento profilático com anti-inflamatórias não esteroides, no grupo de tratamento com anti-inflamatórias não esteroides, no grupo de tratamento profilático com corticosteroides e no grupo de tratamento com corticosteroides foram menores do que as observadas no grupo modelo e maiores que as observadas no grupo negativo. O extravasamento retinal de azul de Evans no grupo de tratamento profilático com anti-inflamatórias não esteroides foi maior que no grupo controle negativo e menor que nos grupos de tratamento com anti-inflamatórias não esteroides, de tratamento profilático com corticosteroides, de tratamento com corticosteroides e no grupo modelo. O extravasamento retinal de azul de Evans observado nos grupos de tratamento com anti-inflamatórias não esteroides, de tratamento profilático com corticosteroides e de tratamento com corticosteroides foi inferior ao observado no grupo modelo. Conclusões: Este estudo valida que o antagonista das prostaglandinas pode aliviar a ruptura da barreira hemato-retiniana em um modelo em ratos e que o tratamento profilático com anti-inflamatórias não esteroides pode alcançar melhor eficácia.

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Tight junctions (TJs) are sites of cell-cell adhesion, constituted by a cytoplasmic plaque of molecules linked to integral proteins that form a network of strands around epithelial and endothelial cells at the uppermost portion of the lateral membrane. TJs maintain plasma membrane polarity and form channels and barriers that regulate the transit of ions and molecules through the paracellular pathway. This structure that regulates traffic between the external milieu and the organism is affected in numerous pathological conditions and constitutes an important target for therapeutic intervention. Here, we describe how a wide array of G protein-coupled receptors that are activated by diverse stimuli including light, ions, hormones, peptides, lipids, nucleotides and proteases, signal through heterotrimeric G proteins, arrestins and kinases to regulate TJs present in the blood-brain barrier, the blood-retinal barrier, renal tubular cells, keratinocytes, lung and colon, and the slit diaphragm of the glomerulus.

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OBJETIVO: Avaliar prospectivamente com o uso da tomografia de coerência óptica se o uso tópico de latanoprosta induz alterações retinianas em pacientes submetidos à cirurgia de catarata. MÉTODOS: Estudo clínico randomizado, com observador mascarado e um mês de duração. Pacientes pseudofácicos foram tratados com latanoprosta (n=10) ou lubrificante ocular uma vez ao dia (grupo controle - placebo) (n=10). Metade dos pacientes de cada grupo possuía capsulotomia posterior (Nd:YAG laser). Avaliamos o status da barreira hemato-retiniana pela medida da espessura retiniana na fóvea com a tomografia de coerência óptica. Exames de tomografia de coerência óptica e medida da acuidade visual foram realizados antes do início do estudo e com 15 e 30 dias de tratamento. RESULTADOS: Não foi observada alteração significante na média da espessura foveal do grupo controle (p>0,0610). Houve aumento significante na média da espessura foveal nos pacientes tratados com latanoprosta (p<0,0004). Não foi observada alteração na acuidade visual em nenhum paciente. A média da espessura retiniana na fóvea foi significativamente maior no grupo da latanoprosta (p<0,0007). A espessura foveal nos olhos tratados com latanoprosta com cápsula posterior rota foi significativamente maior que a dos pacientes com cápsula íntegra (p<0,0461). Comparando apenas os pacientes com cápsula posterior íntegra, houve diferença significante da espessura foveal entre os pacientes tratados com latanoprosta (236,4 ± 29,4 mm) e placebo (197,8 ± 19,3 mm) apenas na avaliação realizada com 30 dias de tratamento. CONCLUSÕES: Latanoprosta pode levar à quebra da barreira hemato-retiniana em pacientes pseudofácicos. Isso é mais provável de ocorrer em pacientes com cápsula posterior rota.

PURPOSE: To study prospectively using optical coherence tomography whether topical latanoprost induces retinal disorders in patients that underwent cataract surgery. METHODS: Randomized, masked-observer, one-month clinical trial. Pseudophakic patients were treated with latanoprost (n=10) or lubricant drop q.d. (control group) (n=10). Half of the patients of each group presented ruptured posterior capsule (Nd:YAG laser). We evaluated the blood-retinal barrier status assessed by optical coherence tomography measurement of retinal thickness in the fovea. Before the beginning of the study and after 15 and 30 days of treatment, optical coherence tomography images were taken, and the visual acuity examination was performed. RESULTS: There was no statistically significant increase in mean foveal thickness when patients instilled placebo (P>0.0610). A statistically significant increase in retinal thickness in the fovea was observed when patients instilled latanoprost (P<0.0004). No changes were observed in visual acuity in both groups. Mean retinal thickness in the fovea was significantly higher in the latanoprost group (P<0.0007). The mean foveal thickness in latanoprost treated eyes with ruptured posterior capsule was statistically greater when compared with that of intact posterior capsule (P<0.0461). When comparing only the patients with that of intact posterior capsule, there was a statistically significant difference in foveal thickness between patients treated with latanoprost (236.4 ± 29.4 mm) and placebo (197.8 ± 19.3 mm) only at 30 days of treatment. CONCLUSIONS: Latanoprost may lead to disruption of the blood-retinal barrier in pseudophakic patients, and is more probable to occur in patients with ruptured posterior capsule.

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