VEGF-R2/Caveolin-1 Pathway of Undifferentiated ARPE-19 Retina Cells: A Potential Target as Anti-VEGF-A Therapy in Wet AMD by Resvega, an Omega-3/Polyphenol Combination

VEGF-R2/CAV-1 Interaction Induced by Resveratrol/Eicosapentaenoic Acid/Docosahexaenoic Acid-Enriched Formulation through Functional Detergent-Resistant Membranes Is Associated with Decreased VEGF-A Release in ARPE-19 Cells

SCOPE

Omega-3 fatty acids (O3FAs) and resveratrol (RSV) are known to be beneficial for certain eye diseases, such as age-related macular degeneration (AMD). Neovascular AMD is characterized by abnormal blood vessel formation due to the excessive synthesis of vascular endothelial growth factor (VEGF) by retinal pigment epithelium (RPE) cells. The study investigates whether a formulation based on eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and RSV is capable of counteracting VEGF-A secretion, and elucidates the molecular mechanism.

METHODS AND RESULTS

The study finds, using ELISA, that O3FAs/RSV reduces VEGF-A secretion in human RPE cells. This phenomenon is related to the increased interaction between VEGF-receptor 2 (VEGF-R2) and caveolin-1 (CAV-1), a protein of detergent-resistant membranes (DRMs), as determined by co-immunoprecipitation and proximity ligation assay. Using microscale thermophoresis, the study confirms that O3FAs/RSV causes a high-affinity interaction. Isolation and analysis of DRMs reveal that this interaction is concomitant with VEGF-R2 relocalization in DRMs. The depletion of DRMs by a cholesterol-chelating agent blocks the VEGF-R2/CAV-1 interaction and EPA/DHA/RSV-mediated impairment of VEGF production.

CONCLUSION

This specific interaction can provide a new strategy for countering VEGF-A production in human RPE cells and, consequently, reducing neovascularization in AMD. Further preclinical studies involving O3FAs and polyphenols are warranted.

One-year outcomes of resveratrol supplement with aflibercept versus aflibercept monotherapy in wet age-related macular degeneration

AIM

To determine the one-year outcomes of resveratrol oral supplement in patients suffering from wet age-related macular degeneration (AMD).

METHODS

Fifty naïve and previously untreated patients suffering from wet AMD, were randomly assigned in two subgroups of 25 patients each. All the participants were treated with 3 monthly intravitreal injections of 2.0 mg aflibercept (IAIs) followed by injections "according to need", while in one group the patients also received daily two tablets of resveratrol oral supplement. Prior to treatment initiation, a complete ophthalmological examination, including best corrected visual acuity (BCVA) and contrast sensitivity evaluation, optical coherence tomography (OCT) scans, fundus autofluorescence (FAF), fluorescein angiography, indocyanine green angiography, and OCT angiography (OCTA), was performed to every participant, while all of them completed the Hospital Anxiety and Depression Scale (HADS) questionnaire, in order to assess their quality of life (QoL) status. The patients were assessed monthly for 1y with FAF, and OCT or OCTA; the main endpoints were the number IAIs, the changes in BCVA, in contrast sensitivity, and in patients' QoL status.

RESULTS

No significant differences were present between the groups regarding the baseline demographic and clinical data. Over the 12-month period, a similar number of IAIs was applied in both groups (4.52±1.00 vs 4.28±0.90, P=0.38), while the rest of the clinical data also did not differ significantly after the completion of the study period. However, for HADS Depression (11.88±2.51 vs 8.28±1.54, P<0.001) and HADS Anxiety (11.92±2.52 vs 7.76±1.51, P<0.001) questionnaires values, the score was significantly better in patients who received resveratrol supplements. Moreover, a statistically significant difference was detected in the mean change from baseline values of contrast sensitivity (0.17±0.19 vs 0.35±0.24, P=0.005), HADS Depression (0.08±1.38 vs -3.88±1.48, P<0.001), and HADS Anxiety (0.36±1.98 vs -5.12±2.70, P<0.001) scores, in favour of the patients treated with resveratrol supplements.

CONCLUSION

The resveratrol oral supplement is a complementary treatment in cases of wet AMD, highlighting its effectiveness in improving patients' QoL status.

Nanotechnology Lighting the Way for Gene Therapy in Ophthalmopathy: From Opportunities toward Applications

Hereditary ophthalmopathy is a well-described threat to human visual health affecting millions of people. Gene therapy for ophthalmopathy has received widespread attention with the increasing understanding of pathogenic genes. Effective and safe delivery of accurate nucleic acid drugs (NADs) is the core of gene therapy. Efficient nanodelivery and nanomodification technologies, appropriate targeted genes, and the choice of drug injection methods are the guiding lights of gene therapy. Compared with traditional drugs, NADs can specifically change the expression of specific genes or restore the normal function of mutant genes. Nanodelivery carriers can improve targeting and nanomodification can improve the stability of NADs. Therefore, NADs, which can fundamentally solve pathogeny, hold great promise in the treatment of ophthalmopathy. This paper reviews the limitations of ocular disease treatment, discusses the classification of NADs in ophthalmology, reveals the delivery strategies of NADs to improve bioavailability, targeting, and stability, and summarizes the mechanisms of NADs in ophthalmopathy.

MAPK Pathways in Ocular Pathophysiology: Potential Therapeutic Drugs and Challenges

Mitogen-activated protein kinase (MAPK) pathways represent ubiquitous cellular signal transduction pathways that regulate all aspects of life and are frequently altered in disease. Once activated through phosphorylation, these MAPKs in turn phosphorylate and activate transcription factors present either in the cytoplasm or in the nucleus, leading to the expression of target genes and, as a consequence, they elicit various biological responses. The aim of this work is to provide a comprehensive review focusing on the roles of MAPK signaling pathways in ocular pathophysiology and the potential to influence these for the treatment of eye diseases. We summarize the current knowledge of identified MAPK-targeting compounds in the context of ocular diseases such as macular degeneration, cataract, glaucoma and keratopathy, but also in rare ocular diseases where the cell differentiation, proliferation or migration are defective. Potential therapeutic interventions are also discussed. Additionally, we discuss challenges in overcoming the reported eye toxicity of some MAPK inhibitors.

Resvega, a Nutraceutical Preparation, Affects NFκB Pathway and Prolongs the Anti-VEGF Effect of Bevacizumab in Undifferentiated ARPE-19 Retina Cells

Age-related macular degeneration (AMD) is an irreversible chronic degenerative pathology that affects the retina. Despite therapeutic advances thanks to the use of anti-vascular endothelial growth factor (VEGF) agents, resistance mechanisms have been found to accentuate the visual deficit. In the present study, we explored whether a nutraceutical formulation composed of omega-3 fatty acids and resveratrol, called Resvega®, was able to disrupt VEGF-A secretion in human ARPE-19 retina cells. We found that Resvega® inhibits VEGF-A secretion through decreases in both the PI3K-AKT-mTOR and NFκB signaling pathways. In NFκB signaling pathways, Resvega® inhibits the phosphorylation of the inhibitor of NFκB, IκB, which can bind NFκB dimers and sequester them in the cytoplasm. Thus, the NFκB subunits cannot migrate to the nucleus where they normally bind and stimulate the transcription of target genes such as VEGF-A. The IκB kinase complex (IKK) is also affected by Resvega® since the nutraceutical formulation decreases both IKKα and IKKβ subunits and the IKKγ subunit which is required for the stimulation of IKK. Very interestingly, we highlight that Resvega® could prolong the anti-angiogenic effect of Avastin®, which is an anti-VEGF agent typically used in clinical practice. Our results suggest that Resvega® may have potential interest as nutritional supplementation against AMD.

Discovering the Potential of Natural Antioxidants in Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD) is a multifactorial disease associated with anatomical changes in the inner retina. Despite tremendous advances in clinical care, there is currently no cure for AMD. This review aims to evaluate the published literature on the therapeutic roles of natural antioxidants in AMD. A literature search of PubMed, Web of Science and Google Scholar for peer-reviewed articles published between 1 January 2011 and 31 October 2021 was undertaken. A total of 82 preclinical and 18 clinical studies were eligible for inclusion in this review. We identified active compounds, carotenoids, extracts and polysaccharides, flavonoids, formulations, vitamins and whole foods with potential therapeutic roles in AMD. We evaluated the integral cellular signaling pathways including the activation of antioxidant pathways and angiogenesis pathways orchestrating their mode of action. In conclusion, we examined the therapeutic roles of natural antioxidants in AMD which warrant further study for application in clinical practice. Our current understanding is that natural antioxidants have the potential to improve or halt the progression of AMD, and tailoring therapeutics to the specific disease stages may be the key to preventing irreversible vision loss.

Caveolin-1 Down-Regulation Reduces VEGF-A Secretion Induced by IGF-1 in ARPE-19 Cells

The insulin-like growth factor 1 (IGF-1) stimulates expression and secretion of vascular endothelial growth factor-A (VEGF-A), the main actor in ocular neovascularization, by RPE cells. Activity of IGF-1 is regulated by interaction between its receptor and Caveolin-1 (Cav-1), the main component of caveolae. The aim of this study was to investigate whether modulation of Cav-1 expression affects synthesis and secretion of VEGF-A. ARPE-19 cells were transfected with small interfering RNA for Cav-1 (si-Cav-1) and with control siRNA (si-CTR) and stimulated with IGF-1. We found that down-regulation of Cav-1 did not affect activation of IGF-1R but regulated in an opposite manner the phosphorylation of Akt and Erk1/2. Moreover, we found that IGF-1 increased mRNA levels of VEGF-A in both si-CTR and in si-Cav-1 ARPE-19 cells and that Cav-1 silencing significantly reduced basal and IGF-1-stimulated VEGF-A release. Then we investigated the response of the microvascular endothelial cell line HMEC-1 to secretory products of ARPE-19 cells by evaluating wound healing closure, finding that conditioned media from si-Cav-1-ARPE-19 cells reduced endothelial cell migration rate. These data demonstrate that Cav-1 regulates secretion of VEGF-A, and that the depletion of Cav-1 reduces IGF-1 induced VEGF-A secretion in ARPE-19 cells and the migratory potential of their secretory products.