Blood-retinal Barrier Research Articles

A Case Report Intravitreal Anti VEGF Bevacizumab on Patient with Hypertension Retinopathy and Exudative Retinal Detachment

Introduction : To present a case of intravitreal anti VEGF bevacizumab function on patient with hypertension retinopathy and exudative retinal detachment.
 Case Illustration : A 29 years old man presented with chief complaint blurry vision with visual acuity 1/60 on both eyes. History of hypertension sinced one year ago and already got hemodialisa treatment twice a week sinced 6 months ago. Ophthalmic examination showed decreased vision on both eyes and posterior segment both eyes we can find macular star and papil edema. Patient had diagnosed with hypertension retinopathy scheie 4 and exudative retinal detachment both eyes.
 Discussion : Hypertension will cause blood vessels to become damage in the form of sclerosis, thickening of blood vessel walls, and plasma leakage. Hypertension retinopathy acts as predictor of systemic morbidity and mortality due to organ target damage. Regulating systemic disease like blood pressure to become normal will improve clinical signs of hypertension retinopathy. Administration of anti-VEGF intravitreal injection therapy like bevacizumab can improve permeability of blood vessels in retina and decreased volume of exudate in retina. Visual acuity for this patient will improve to become 4/60 for both eyes.
 Conclusion : Uncontrolled hypertension can lead to organ target damage, which one of that was eyes. Hypertension retinopathy can make complications like exudative retinal detachment if the blood pressure still uncontrolled. Management of exudative retinal detachment caused by hypertension retinopathy was giving intravitreal anti VEGF injection in eyes to repair breakdown of blood retinal barrier, and the blood pressure must be well controlled to maintain permeability of blood retinal barrier.

Complete Resolution of Central Serous Chorioretinopathy Cases Treated with Low Power Mode Laser Technology : A Novel Approach

Introduction : Central serous chorioretinopathy (CSC) is an idiopathic condition mostly affecting men in their 20s to 50s. It is characterized by serous fluid accumulation behind the neurosensory retina resulting in a localized macular detachment. Aldosterone-receptor antagonist and photodynamic laser therapy are the current mainstay of treatments, although most CSC cases can resolves spontaneously within 2 to 3 months. Low power mode (LPM) laser has emerged as a new effective technology to treat CSC.
 Case Illustration : Case 1: A 50-year-old male was diagnosed with recurrent chronic CSC since 2 months ago. His visual acuity declined even after given oral aldosterone receptor antagonist for two weeks, so he was scheduled to undergo LPM. After three weeks of laser treatment, CSC resolved and the visual acuity improved (Figure1). Case 2 : A 47-year-old male complained of decreased vision and metamorphopsia on his right eye since two weeks ago. He was diagnosed with CSC and underwent LPM. Three weeks after LPM, his vision improved and the metamorphopsia resolved (Figure2). LPM helps the migration of retinal pigment epithelium (RPE) cells to restore the outer blood-retinal barrier through expression of heat shock proteins. We used MC-500ViXi laser system (Nidek Co., Gamagori, Japan) and the laser parameters used in this study were 100?m spot size, 0.01s exposure time, 0.25-0.5 spacing, and 30% LPM ratio.
 Discussion : 
 Conclusion : LPM is a new yet promising treatment modalities to treat acute and chronic CSC. Its low power nature makes LPM a safe choice of treatment with less damage to the surrounding retina.

Porous Se@SiO2 nanospheres alleviate diabetic retinopathy by inhibiting excess lipid peroxidation and inflammation

BackgroundLipid peroxidation is a characteristic metabolic manifestation of diabetic retinopathy (DR) that causes inflammation, eventually leading to severe retinal vascular abnormalities. Selenium (Se) can directly or indirectly scavenge intracellular free radicals. Due to the narrow distinction between Se’s effective and toxic doses, porous Se@SiO2 nanospheres have been developed to control the release of Se. They exert strong antioxidant and anti-inflammatory effects.MethodsThe effect of anti-lipid peroxidation and anti-inflammatory effects of porous Se@SiO2 nanospheres on diabetic mice were assessed by detecting the level of Malondialdehyde (MDA), glutathione peroxidase 4 (GPX4), decreased reduced/oxidized glutathione (GSH/GSSG) ratio, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL) -1β of the retina. To further examine the protective effect of porous Se@SiO2 nanospheres on the retinal vasculopathy of diabetic mice, retinal acellular capillary, the expression of tight junction proteins, and blood–retinal barrier destruction was observed. Finally, we validated the GPX4 as the target of porous Se@SiO2 nanospheres via decreased expression of GPX4 and detected the level of MDA, GSH/GSSG, TNF-α, IFN-γ, IL -1β, wound healing assay, and tube formation in high glucose (HG) cultured Human retinal microvascular endothelial cells (HRMECs).ResultsThe porous Se@SiO2 nanospheres reduced the level of MDA, TNF-α, IFN-γ, and IL -1β, while increasing the level of GPX4 and GSH/GSSG in diabetic mice. Therefore, porous Se@SiO2 nanospheres reduced the number of retinal acellular capillaries, depletion of tight junction proteins, and vascular leakage in diabetic mice. Further, we identified GPX4 as the target of porous Se@SiO2 nanospheres as GPX4 inhibition reduced the repression effect of anti-lipid peroxidation, anti-inflammatory, and protective effects of endothelial cell dysfunction of porous Se@SiO2 nanospheres in HG-cultured HRMECs.ConclusionPorous Se@SiO2 nanospheres effectively attenuated retinal vasculopathy in diabetic mice via inhibiting excess lipid peroxidation and inflammation by target GPX4, suggesting their potential as therapeutic agents for DR.

Molecular Mechanisms and Therapeutic Implications of Human Pericyte-like Adipose-Derived Mesenchymal Stem Cells in an In Vitro Model of Diabetic Retinopathy.

The blood-retinal barrier (BRB) is strongly compromised in diabetic retinopathy (DR) due to the detachment of pericytes (PCs) from retinal microvessels, resulting in increased permeability and impairment of the BRB. Western blots, immunofluorescence and ELISA were performed on adipose mesenchymal stem cells (ASCs) and pericyte-like (P)-ASCs by co-cultured human retinal endothelial cells (HRECs) under hyperglycemic conditions (HG), as a model of DR. Our results demonstrated that: (a) platelet-derived growth factor receptor (PDGFR) and its activated form were more highly expressed in monocultured P-ASCs than in ASCs, and this expression increased when co-cultured with HRECs under high glucose conditions (HG); (b) the transcription factor Nrf2 was more expressed in the cytoplasmic fraction of ASCs and in the P-ASC nuclear fraction, under normal glucose and, even more, under HG conditions; (c) cytosolic phospholipase A2 activity and prostaglandin E2 release, stimulated by HG, were significantly reduced in P-ASCs co-cultured with HRECs; (d) HO-1 protein content was significantly higher in HG-P-ASCs/HRECs than P-ASCs/HRECs; and (e) VEGF-A levels in media from HG-co-cultures were reduced in P-ASCs/HRECs with respect to ASCs/HRECs. The data obtained highlighted the potential of autologous differentiated ASCs in future clinical applications based on cell therapy to counteract the damage induced by DR.

Short histological kaleidoscope - recent findings in histology. Part IV.

The paper provides an overview of the current understanding of different cells and structures' biology [e.g., blood-retinal barrier, Bruch membrane, Clara (club) cells, brush cells and tuft cells, Merkel cells, Hofbauer cells, cytokeratins], including their origin, structure, function, and role in disease pathogenesis, and of the latest findings in the medical literature concerning the paracortex of the lymph nodes.

Glaucoma: from pathogenic mechanisms to retinal glial cell response to damage

Glaucoma is a neurodegenerative disease of the retina characterized by the irreversible loss of retinal ganglion cells (RGCs) leading to visual loss. Degeneration of RGCs and loss of their axons, as well as damage and remodeling of the lamina cribrosa are the main events in the pathogenesis of glaucoma. Different molecular pathways are involved in RGC death, which are triggered and exacerbated as a consequence of a number of risk factors such as elevated intraocular pressure (IOP), age, ocular biomechanics, or low ocular perfusion pressure. Increased IOP is one of the most important risk factors associated with this pathology and the only one for which treatment is currently available, nevertheless, on many cases the progression of the disease continues, despite IOP control. Thus, the IOP elevation is not the only trigger of glaucomatous damage, showing the evidence that other factors can induce RGCs death in this pathology, would be involved in the advance of glaucomatous neurodegeneration. The underlying mechanisms driving the neurodegenerative process in glaucoma include ischemia/hypoxia, mitochondrial dysfunction, oxidative stress and neuroinflammation. In glaucoma, like as other neurodegenerative disorders, the immune system is involved and immunoregulation is conducted mainly by glial cells, microglia, astrocytes, and Müller cells. The increase in IOP produces the activation of glial cells in the retinal tissue. Chronic activation of glial cells in glaucoma may provoke a proinflammatory state at the retinal level inducing blood retinal barrier disruption and RGCs death. The modulation of the immune response in glaucoma as well as the activation of glial cells constitute an interesting new approach in the treatment of glaucoma.

The supplementation of a high dose of fish oil during pregnancy and lactation led to an elevation in Mfsd2a expression without any changes in docosahexaenoic acid levels in the retina of healthy 2-month-old mouse offspring.

During fetal development, the proper development of neural and visual systems relies on the maternal supplementation of omega-3 fatty acids through placental transfer. Pregnant women are strongly advised to augment their diet with additional sources of omega-3, such as fish oil (FO). This supplementation has been linked to a reduced risk of preterm birth, pre-eclampsia, and perinatal depression. Recently, higher doses of omega-3 supplementation have been recommended for pregnant women. Considering that omega-3 fatty acids, particularly docosahexaenoic acid (DHA), play a crucial role in maintaining the delicate homeostasis required for the proper functioning of the retina and photoreceptors the effects of high-dose fish oil (FO) supplementation during pregnancy and lactation on the retina and retinal pigmented epithelium (RPE) in healthy offspring warrant better understanding. The fatty acid content and the changes in the expression of the genes regulating cholesterol homeostasis and DHA transport in the retina and RPE were evaluated following the high-dose FO supplementation. Our study demonstrated that despite the high-dose FO treatment during pregnancy and lactation, the rigorous DHA homeostasis in the retina and RPE of the two-month-old offspring remained balanced. Another significant finding of this study is the increase in the expression levels of major facilitator superfamily domain-containing protein (Mfsd2a), a primary DHA transporter. Mfsd2a also serves as a major regulator of transcytosis during development, and a reduction in Mfsd2a levels poses a major risk for the development of leaky blood vessels. Impairment of the blood-retinal barrier (BRB) is associated with the development of numerous ocular diseases, and a better understanding of how to manipulate transcytosis in the BRB during development can enhance drug delivery through the BRB or contribute to the repair of central nervous system (CNS) barriers.

Response of Human Retinal Microvascular Endothelial Cells to Influenza A (H1N1) Infection and the Underlying Molecular Mechanism.

Whether H1N1 infection-associated ocular manifestations result from direct viral infections or systemic complications remains unclear. This study aimed to comprehensively elucidate the underlying causes and mechanism. TCID50 assays was performed at 24, 48, and 72hours to verify the infection of H1N1 in human retinal microvascular endothelial cells (HRMECs). The changes in gene expression profiles of HRMECs at 24, 48, and 72hours were characterized using RNA sequencing technology. Differentially expressed genes (DEGs) were validated using real-time quantitative polymerase chain reaction and Western blotting. CCK-8 assay and scratch assay were performed to evaluate whether there was a potential improvement of proliferation and migration in H1N1-infected cells after oseltamivir intervention. H1N1 can infect and replicate within HRMECs, leading to cell rounding and detachment. After H1N1 infection of HRMECs, 2562 DEGs were identified, including 1748 upregulated ones and 814 downregulated ones. These DEGs primarily involved in processes such as inflammation and immune response, cytokine-cytokine receptor interaction, signal transduction regulation, and cell adhesion. The elevated expression levels of CXCL10, CXCL11, CCL5, TLR3, C3, IFNB1, IFNG, STAT1, HLA, and TNFSF10 after H1N1 infection were reduced by oseltamivir intervention, reaching levels comparable to those in the uninfected group. The impaired cell proliferation and migration after H1N1 infection was improved by oseltamivir intervention. This study confirmed that H1N1 can infect HRMECs, leading to the upregulation of chemokines, which may cause inflammation and destruction of the blood-retina barrier. Moreover, early oseltamivir administration may reduce retinal inflammation and hemorrhage in patients infected with H1N1.

Diabetic Macular Edema Management: A Review of Anti-Vascular Endothelial Growth Factor (VEGF) Therapies.

Diabetic macular edema (DME) is a major cause of vision impairment in diabetic individuals, characterized by fluid accumulation in the macula due to a breakdown of the blood-retinal barrier (BRB). This review article explores the role of anti-vascular endothelial growth factor (anti-VEGF) therapies in the management of DME. Anti-VEGF treatments, including ranibizumab, bevacizumab, and aflibercept, have revolutionized DME management by targeting VEGF, a key mediator in DME pathogenesis. We critically examined the efficacy of these therapies in reducing macular edema and improving visual acuity, assessed their safety and tolerability, and explored the variability in treatment response. The review highlights the latest advancements and future directions in anti-VEGF therapy, including novel drug delivery systems and emerging treatment paradigms. By providing a comprehensive overview of current anti-VEGF therapies, this review seeks to inform clinical practice, guide future research, and contribute to improved patient outcomes in DME management.

Benefits and Caveats in the Use of Retinal Pigment Epithelium-Specific Cre Mice.

The retinal pigment epithelium (RPE) is an important monolayer of cells present in the outer retina, forming a major part of the blood-retina barrier (BRB). It performs many tasks essential for the maintenance of retinal integrity and function. With increasing knowledge of the retina, it is becoming clear that both common retinal disorders, like age-related macular degeneration, and rare genetic disorders originate in the RPE. This calls for a better understanding of the functions of various proteins within the RPE. In this regard, mice enabling an RPE-specific gene deletion are a powerful tool to study the role of a particular protein within the RPE cells in their native environment, simultaneously negating any potential influences of systemic changes. Moreover, since RPE cells interact closely with adjacent photoreceptors, these mice also provide an excellent avenue to study the importance of a particular gene function within the RPE to the retina as a whole. In this review, we outline and compare the features of various Cre mice created for this purpose, which allow for inducible or non-inducible RPE-specific knockout of a gene of interest. We summarize the various benefits and caveats involved in the use of such mouse lines, allowing researchers to make a well-informed decision on the choice of Cre mouse to use in relation to their research needs.

HIV-1 gp120 amplifies astrocyte elevated gene-1 activity to compromise the integrity of the outer blood-retinal barrier.

This study aims to investigate the functions and mechanistic pathways of Astrocyte Elevated Gene-1 (AEG-1) in the disruption of the blood-retinal barrier (BRB) caused by the HIV-1 envelope glycoprotein gp120. We utilized ARPE-19 cells challenged with gp120 as our model system. Several analytical techniques were employed to decipher the intricate interactions at play. These included PCR, Western blot, and immunofluorescence assays for the molecular characterization, and transendothelial electrical resistance (TEER) measurements to evaluate barrier integrity. We observed that AEG-1 expression was elevated, whereas the expression levels of tight junction proteins ZO-1, Occludin, and Claudin5 were downregulated in gp120-challenged cells. TEER measurements corroborated these findings, indicating barrier dysfunction. Additional mechanistic studies revealed that the activation of NFκB and MMP2/9 pathways mediated the AEG-1-induced barrier destabilization. Through the use of lentiviral vectors, we engineered cell lines with modulated AEG-1 expression levels. Silencing AEG-1 alleviated gp120-induced downregulation of tight junction proteins and barrier impairment while concurrently inhibiting the NFκB and MMP2/9 pathways. Conversely, overexpression of AEG-1 exacerbated these pathological changes, further compromising the integrity of the BRB. Gp120 upregulates the expression of AEG-1 and activates the NFκB and MMP2/9 pathways. This in turn leads to the downregulation of tight junction proteins, resulting in the disruption of barrier function.

Single-Cell Transcriptomic Sequencing Reveals Tissue Architecture and Deciphers Pathological Reprogramming During Retinal Ischemia in Macaca fascicularis.

Acute retinal arterial ischemia diseases (ARAIDs) are ocular emergencies that require immediate intervention within a restricted therapeutic window to prevent blindness. However, the underlying molecular mechanisms contributing to the pathogenesis of ARAIDs remain enigmatic. Herein, we present the single-cell RNA sequencing (scRNA-seq) alterations during ischemia in the primate retina as a preliminary endeavor in understanding the molecular complexities of ARAIDs. An ophthalmic artery occlusion model was established through ophthalmic artery ligation in two Macaca fascicularis. scRNA-seq and bioinformatics analyses were used to detect retinal changes during ischemia, which are further validated by immunofluorescence analysis. Western blot and flow cytometry assays were performed to measure the microglia polarization status. The findings of this study reveal notable changes in the retina under acute ischemic conditions. Particularly, retinal ischemia compromised mitochondrial functions of rod photoreceptors, partly leading to the rapid loss of healthy rods. Furthermore, we observed a noteworthy transcriptional alteration in the activation of microglia induced by ischemia. The targeted correction of the proinflammatory cytokine CXCL8 effectively suppresses microglia M1 polarization in retinal ischemia, ultimately reducing the proinflammatory transformation in vitro. In addition, retina ischemia induced the apoptotic inclination of endothelial cells and the heightened interaction with microglia, which signifies the influence of microglia in disrupting the retinal-blood barrier. Our research has successfully identified and described the pathologic alterations occurring in several cell types during a short period of ischemia. These observations provide valuable insights for ameliorating retinal damage and promoting the restoration of vision.

Neurovascular Relationships in AGEs-Based Models of Proliferative Diabetic Retinopathy.

Diabetic retinopathy affects more than 100 million people worldwide and is projected to increase by 50% within 20 years. Increased blood glucose leads to the formation of advanced glycation end products (AGEs), which cause cellular and molecular dysfunction across neurovascular systems. These molecules initiate the slow breakdown of the retinal vasculature and the inner blood retinal barrier (iBRB), resulting in ischemia and abnormal angiogenesis. This project examined the impact of AGEs in altering the morphology of healthy cells that comprise the iBRB, as well as the effects of AGEs on thrombi formation, in vitro. Our results illustrate that AGEs significantly alter cellular areas and increase the formation of blood clots via elevated levels of tissue factor. Likewise, AGEs upregulate the expression of cell receptors (RAGE) on both endothelial and glial cells, a hallmark biomarker of inflammation in diabetic cells. Examining the effects of AGEs stimulation on cellular functions that work to diminish iBRB integrity will greatly help to advance therapies that target vision loss in adults.

Sex‐related differences in the visual function of an animal model of type 1 diabetes

Aims/Purpose: Recent basic and clinical research evidence suggests that male–female differences may influence retinal function and structure. It is also well‐established that diabetes affects retinal function. This work aimed to assess whether type 1 diabetes differentially affects neuroretinal function in male and female Wistar rats.Methods: To induce type 1 diabetes, male and female Wistar rats were injected (i.p.) with streptozotocin (65 mg/kg). Electroretinograms (ERGs) were recorded before and 1, 2, and 4 weeks after diabetes induction (n = 12–13 animals/group). To assess the effect of chronic hyperglycemia on the content of molecular components of the blood‐retinal barrier (BRB), specific tight junction proteins were assessed by Western Blotting. Neuroinflammation was evaluated by measuring the retinal levels of pro‐inflammatory cytokines.Results: Some sex‐related changes in retinal function were detected in the diabetic animals. Overall, in male diabetic rats, compared to control male rats, the differences found under scotopic conditions were mainly in the positive scotopic threshold response (pSTR), with decreased amplitudes (at weeks 2 and 4), and higher latencies (at weeks 1 and 4). In contrast, diabetic female rats, compared to control females, presented a higher increase in the latency value of the negative STR (nSTR; at weeks 1 and 4), a‐wave (at weeks 1, 2, and 4), and oscillatory potentials 2, 3, and 4 (at weeks 1, 2, and 4). Under photopic conditions, male diabetic rats showed higher implicit time values of the fundamental flicker wave (at week 4) and a decrease in the amplitude of the flicker 2nd harmonic (at week 4) compared to control males. Conversely, in diabetic female rats, there were no differences in these parameters compared to control female rats. Concerning the BRB and neuroinflammation, no changes were found in diabetic males and females compared to their respective controls.Conclusions: Our findings suggest that type 1 diabetes differentially affects the retinal function in male and female Wistar rats.Support: FCT‐Portugal: PEst UIDB/04539/2020 and UIDP/04539/2020; 2020.07432.BD.

Obstruction and Approaches to Cross the Drug Molecules through Blood Retinal Barrier: An Overview

Obstruction and Approaches to Cross the Drug Molecules through Blood Retinal Barrier: An Overview

Discordance of Aqueous/Plasma HIV Replication on ART.

The study was conducted to analyze HIV dynamics across blood-retinal barrier (BRB) and the relevant risk factors for HIV-associated ocular complications. This study included a case series of 40 HIV-positive patients with ocular lesions, which were studied retrospectively. Clinical and laboratory examinations included plasma and intraocular viral load (VL). HIV VL on paired aqueous/plasma samples was available for 40 patients. Aqueous VL was negatively associated with antiretroviral treatment (ART) duration (p = 0.02 and p < 0.05), and plasma VL was independent of ART duration (p = 0.53). An aqueous/plasma discordance was found in 19/40 (47.5%) patients, eight of whom (20%) had detectable aqueous VL despite a suppressed plasma VL (escape). There were significant differences in CD4+ T-lymphocyte levels (p = 0.011 and p < 0.05) and ART duration (p = 0.007 and p < 0.05) between the patients with HIV-associated ocular complications and the patients without. This study provides a rationale for initiating ART early in the course of infection to reduce HIV VL in the aqueous humor, and raises the possibility of the ocular sanctuary where HIV replicates. Meanwhile, early and standard ART would be an optimal option to protect against ocular opportunistic infection.

Fenofibrate and diabetic retinopathy.

Diabetic retinopathy (DR), a sight-threatening ocular complication of diabetes mellitus, is one of the main causes of blindness in the working-age population. Dyslipidemia is a potential risk factor for the development or worsening of DR, with conflicting evidence in epidemiological studies. Fenofibrate, an antihyperlipidemic agent, has lipid-modifying and pleiotropic (non-lipid) effects that may lessen the incidence of microvascular events. Relevant studies were identified through a PubMed/MEDLINE search spanning the last 20 years, using the broad term "diabetic retinopathy" and specific terms "fenofibrate" and "dyslipidemia". References cited in these studies were further examined to compile this mini-review. These pivotal investigations underwent meticulous scrutiny and synthesis, focusing on methodological approaches and clinical outcomes. Furthermore, we provided the main findings of the seminal studies in a table to enhance comprehension and comparison. Growing evidence indicates that fenofibrate treatment slows DR advancement owing to its possible protective effects on the blood-retinal barrier. The protective attributes of fenofibrate against DR progression and development can be broadly classified into two categories: lipid-modifying effects and non-lipid-related (pleiotropic) effects. The lipid-modifying effect is mediated through peroxisome proliferator-activated receptor-α activation, while the pleiotropic effects involve the reduction in serum levels of C-reactive protein, fibrinogen, and pro-inflammatory markers, and improvement in flow-mediated dilatation. In patients with DR, the lipid-modifying effects of fenofibrate primarily involve a reduction in lipoprotein-associated phospholipase A2 levels and the upregulation of apolipoprotein A1 levels. These changes contribute to the anti-inflammatory and anti-angiogenic effects of fenofibrate. Fenofibrate elicits a diverse array of pleiotropic effects, including anti-apoptotic, antioxidant, anti-inflammatory, and anti-angiogenic properties, along with the indirect consequences of these effects. Two randomized controlled trials-the Fenofibrate Intervention and Event Lowering in Diabetes and Action to Control Cardiovascular Risk in Diabetes studies-noted that fenofibrate treatment protected against DR progression, independent of serum lipid levels. Fenofibrate, an oral antihyperlipidemic agent that is effective in decreasing DR progression, may reduce the number of patients who develop vision-threatening complications and require invasive treatment. Despite its proven protection against DR progression, fenofibrate treatment has not yet gained wide clinical acceptance in DR management. Ongoing and future clinical trials may clarify the role of fenofibrate treatment in DR management.

The role of pericyte in ocular vascular diseases.

Pericytes are located in the stromal membrane of the capillary outer wall and contain endothelial cells (ECs). They are pivotal in regulating blood flow, enhancing vascular stability, and maintaining the integrity of the blood-retina barrier (BRB)/blood-brain barrier (BBB). The pluripotency of pericytes allows them to differentiate into various cell types, highlighting their significance in vascular disease pathogenesis, as demonstrated by previous studies. This potential enables pericytes to be a potential biomarker for the diagnosis and a target for treatment of vascular disorders. The retina, an essential part of the eyeball, is an extension of cerebral tissue with a transparent refractive medium. It offers a unique window for assessing systemic microvascular lesions. Routine fundus examination is necessary for patients with diabetes and hypertension. Manifestations, such as retinal artery tortuosity, dilation, stenosis, and abnormal arteriovenous anastomosis, serve as typical hallmarks of retinal vasculopathy. Therefore, studies of ocular vascular diseases significantly facilitate the exploration of systemic vascular diseases.

Monomeric C‐reactive protein exacerbates choroidal neovascularization in vivo: Implications for age‐related macular degeneration

Aims/Purpose: Increased systemic levels of the acute phase reactant C‐reactive protein (CRP) have been linked to increased risk of age‐related macular degeneration (AMD). CRP undergoes conformational changes upon activation in inflammatory microenvironments between pentameric (pCRP) and monomeric forms (mCRP). CRP conformations present different phenotypes, as mCRP has more proinflammatory properties and has been shown to induce blood retinal barrier disruption in vitro. Thus, we aimed to evaluate the impact of CRP forms on choroidal neovascularization (CNV) in vivo.Methods: pCRP and mCRP forms were intravenously (iv) or intravitreally (ivt) injected in C57BL6/J mice (n = 12) previously subjected to CNV induction by laser and compared to controls. CNV lesions were monitored by fluorescein angiography and mice were euthanized 11 days after lesion induction. CNV areas were measured in lectin stained choroidal flatmounts. To evaluate the CRP dissociation, pCRP was coupled to a fluorescent molecule before injection. After tissue extraction mCRP was detected by immunofluorescence in posterior pole flatmounts.Results: Both pCRP and mCRP injected significantly increased CNV areas compared to control mice. Retinal severe edema was also observed close to the lesion in retinographies, and was more severe in intravitreally injected groups. Finally, pCRP was observed to dissociate into mCRP in intravitreally injected animals with pCRP.Conclusions: We confirmed that CRP increases CNV areas and severe edema in the retina, suggesting that CRP is activated in the CNV inflammatory environment. Additionally, the pCRP form dissociates in vivo into mCRP close to CNV damaged tissue, hypothesizing that mCRP is the CRP conformation that contributes to the exacerbation of the CNV process. Further studies are needed to investigate anti‐mCRP molecules as candidates for mono‐ or anti‐VEGF combined therapy for AMD treatments.

Serum-deprivation response of ARPE-19 cells; expression patterns relevant to age-related macular degeneration.

ARPE-19 cells are derived from adult human retinal pigment epithelium (RPE). The response of these cells to the stress of serum deprivation mimics some important processes relevant to age-related macular degeneration (AMD). Here we extend the characterization of this response using RNASeq and EGSEA gene set analysis of ARPE-19 cells over nine days of serum deprivation. This experiment confirmed the up-regulation of cholesterol and lipid-associated pathways that increase cholesterol levels in these cells. The gene expression analysis also identified other pathways relevant to AMD progression. There were significant changes in extracellular matrix gene expression, notably a switch from expression of collagen IV, a key component of Bruch's membrane (part of the blood-retina barrier), to expression of a fibrosis-like collagen type I matrix. Changes in the expression profile of the extracellular matrix led to the discovery that amelotin is induced in AMD and is associated with the development of the calcium deposits seen in late-stage geographic atrophy. The transcriptional profiles of other pathways, including inflammation, complement, and coagulation, were also modified, consistent with immune response patterns seen in AMD. As previously noted, the cells resist apoptosis and autophagy but instead initiate a gene expression pattern characteristic of senescence, consistent with the maintenance of barrier function even as other aspects of RPE function are compromised. Other differentially regulated genes were identified that open new avenues for investigation. Our results suggest that ARPE-19 cells maintain significant stress responses characteristic of native RPE that are informative for AMD. As such, they provide a convenient system for discovery and for testing potential therapeutic interventions.