Role of ω3 polyunsaturated fatty acids in diabetic retinopathy: a morphological and metabolically cross talk among blood retina barriers damage, autoimmunity and chronic inflammation

Association between fatty acid intake and age-related macular degeneration: a meta-analysis

Objective

The association of age-related macular degeneration (AMD) with the intake of high and low fatty acids (FAs), respectively, remains controversial. To this end, we performed a comprehensive meta-analysis of all the existing studies on the association of various intake levels of FA subtypes with AMD to determine these associations.

Methods

A systematic search of PubMed, Web of Science, Cochrane Library, and EMBASE databases was conducted from inception to September 2023. To compare the highest and lowest groups, odds ratio (OR) with 95% confidence intervals (CIs) was analyzed with a random-effects model/fixed-effects model.

Results

A high intake of omega-3 LCPUFAs (OR:0.67; 95%CI:[0.51, 0.88]; p = 0.004), DHA (OR:0.80; 95%CI:[0.70, 0.90]; p < 0.001), EPA (OR:0.91; 95%CI:[0.86, 0.97]; p = 0.004), and simultaneous intake of DHA and EPA (OR:0.79; 95%CI:[0.67, 0.93]; p = 0.035) significantly reduced the risk of overall AMD. Conversely, a high intake of trans-FAs (OR: 2.05; 95%CI: [1.29, 3.25]; p = 0.002) was significantly related to an increased risk of advanced AMD compared to the low-intake group. The subgroup analysis results are shown in the articles.

Conclusion

Increasing dietary intake of omega-3 LCPUFAs, specifically DHA, and EPA, or the simultaneous intake of DHA and EPA, is significantly associated with a reduced risk of overall AMD. Various subtypes of omega-3 also have a significant association with a reduced risk of different stages of AMD. The high intake of trans-fatty acids (TFAs) is significantly and positively correlated with the risk of advanced AMD. This could further support the idea that consuming foods rich in omega-3 LCPUFAs and reducing consumption of foods rich in TFAs may prevent AMD.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023467227.

Nutraceuticals for Diabetic Retinopathy: Recent Advances and Novel Delivery Systems

Diabetic retinopathy (DR) is a major vision-threatening disease among the working-age population worldwide. Present therapeutic strategies such as intravitreal injection of anti-VEGF and laser photocoagulation mainly target proliferative DR. However, there is a need for early effective management in patients with early stage of DR before its progression into the more severe sight-threatening proliferative stage. Nutraceuticals, natural functional foods with few side effects, have been proposed to be beneficial in patients with DR. Over the decades, many studies, either in vitro or in vivo, have demonstrated the advantages of a number of nutraceuticals in DR with their antioxidative, anti-inflammatory, neuroprotective, or vasoprotective effects. However, only a few clinical trials have been conducted, and their outcomes varied. The low bioavailability and instability of many nutraceuticals have indeed hindered their utilization in clinical use. In this context, nanoparticle carriers have been developed to deliver nutraceuticals and to improve their bioavailability. Despite its preclinical nature, research of interventive nutraceuticals for DR may yield promising information in their clinical applications.

Unveiling the gut-eye axis: how microbial metabolites influence ocular health and disease

The intricate interplay between the gut microbiota and ocular health has surpassed conventional medical beliefs, fundamentally reshaping our understanding of organ interconnectivity. This review investigates into the intricate relationship between gut microbiota-derived metabolites and their consequential impact on ocular health and disease pathogenesis. By examining the role of specific metabolites, such as short-chain fatty acids (SCFAs) like butyrate and bile acids (BAs), herein we elucidate their significant contributions to ocular pathologies, thought-provoking the traditional belief of organ sterility, particularly in the field of ophthalmology. Highlighting the dynamic nature of the gut microbiota and its profound influence on ocular health, this review underlines the necessity of comprehending the complex workings of the gut-eye axis, an emerging field of science ready for further exploration and scrutiny. While acknowledging the therapeutic promise in manipulating the gut microbiome and its metabolites, the available literature advocates for a targeted, precise approach. Instead of broad interventions, it emphasizes the potential of exploiting specific microbiome-related metabolites as a focused strategy. This targeted approach compared to a precision tool rather than a broad-spectrum solution, aims to explore the therapeutic applications of microbiome-related metabolites in the context of various retinal diseases. By proposing a nuanced strategy targeted at specific microbial metabolites, this review suggests that addressing specific deficiencies or imbalances through microbiome-related metabolites might yield expedited and pronounced outcomes in systemic health, extending to the eye. This focused strategy holds the potential in bypassing the irregularity associated with manipulating microbes themselves, paving a more efficient pathway toward desired outcomes in optimizing gut health and its implications for retinal diseases.

Association between blood urea nitrogen levels and diabetic retinopathy in diabetic adults in the United States (NHANES 2005-2018)

Objective

To investigate the association between blood urea nitrogen (BUN) levels and diabetic retinopathy (DR) in adults with diabetes mellitus (DM).

Methods

Seven cycles of cross-sectional population information acquired from NHANES(national health and nutrition examination surveys) 2005-2018 were collected, from which a sample of diabetic adults was screened and separated into two groups based on whether or not they had DR, followed by weighted multivariate regression analysis. This study collected a complete set of demographic, biological, and sociological risk factor indicators for DR. Demographic risk factors comprised age, gender, and ethnicity, while biological risk factors included blood count, blood pressure, BMI, waist circumference, and glycated hemoglobin. Sociological risk factors included education level, deprivation index, smoking status, and alcohol consumption.

Results

The multiple regression model revealed a significant connection between BUN levels and DR [odds ratio =1.04, 95% confidence interval (1.03-1.05), p-value <0.0001],accounting for numerous variables. After equating BUN levels into four groups, multiple regression modeling showed the highest quartile (BUN>20 mg/dl) was 2.22 times more likely to develop DR than the lowest quartile [odds ratio =2.22, 95% confidence interval (1.69-2.93), p- value <0.0001]. Subgroup analyses revealed that gender, race, diabetes subtype, and duration of diabetes had a regulating effect on the relationship between BUN and DR.

Conclusion

BUN levels were related with an increased prevalence of DR, particularly in individuals with BUN >20 mg/dl. These findings highlight the significance of BUN level in assessing the risk of DR.

Restoring retinal polyunsaturated fatty acid balance and retina function by targeting ceramide in AdipoR1-deficient mice

Mutations in the adiponectin receptor 1 gene (AdipoR1) lead to retinitis pigmentosa and are associated with age-related macular degeneration. This study explores the effects of AdipoR1 gene deficiency in mice, revealing a striking decline in ω3 polyunsaturated fatty acids (PUFA), an increase in ω6 fatty acids, and elevated ceramides in the retina. The AdipoR1 deficiency impairs peroxisome proliferator-activated receptor α signaling, which is crucial for FA metabolism, particularly affecting proteins associated with FA transport and oxidation in the retina and retinal pigmented epithelium. Our lipidomic and proteomic analyses indicate changes that could affect membrane composition and viscosity through altered ω3 PUFA transport and synthesis, suggesting a potential influence of AdipoR1 on these properties. Furthermore, we noted a reduction in the Bardet-Biedl syndrome proteins, which are crucial for forming and maintaining photoreceptor outer segments that are PUFA-enriched ciliary structures. Diminution in Bardet-Biedl syndrome-proteins content combined with our electron microscopic observations raises the possibility that AdipoR1 deficiency might impair ciliary function. Treatment with inhibitors of ceramide synthesis led to substantial elevation of ω3 LC-PUFAs, alleviating photoreceptor degeneration and improving retinal function. These results serve as the proof of concept for a ceramide-targeted strategy to treat retinopathies linked to PUFA deficiency, including age-related macular degeneration.

Correlation between omega-3 intake and the incidence of diabetic retinopathy based on NHANES from 2005 to 2008

AIMS

To identify correlations between omega-3 intake and incidence of diabetic retinopathy (DR).

METHODS

This was a cross-sectional study using data from participants over age 40 in the National Health and Nutrition Examination Survey (NHANES) 2005-2008. Metrics included participants' intake of omega-3 fatty acids, specifically three types of representative polyunsaturated fatty acids, DR prevalence, and demographic characteristics. Multiple logistic regression models were used to assess the relationship between omega-3 intake and DR.

RESULTS

Of the 1243 participants included in this study, omega-3 intake was lower in patients with DR relative to those without DR. Of the three polyunsaturated fatty acids within the omega-3 fatty acid family that we focused on, participants without DR consumed more docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) than those with DR. In contrast, there was no significant difference in the intake of eicosapentaenoic acid (EPA). Higher omega-3 intake was associated with a decreased risk of DR. In a crude model, the odds ratio (OR) was 0.548 (95% CI 0.315, 0.951; p = 0.033). In the fully adjusted model of omega-3 (model II), the adjusted OR was 0.525 (95% CI 0.306, 0.901; p = 0.021). DPA and DHA were also associated with a decreased risk of DR. In the full adjustment model (model II) of DPA and DHA, the adjusted ORs were 0.0002 (95% CI 0.000, 0.166; p = 0.014) and 0.293 (95% CI 0.105, 0.819; p = 0.020). Subgroup analysis showed that the protective effect of omega-3 against DR was more significant in younger patients (p value = 0.015).

CONCLUSIONS

In this cross-sectional study of the U.S. general population, we found that increased intake of omega-3 and its components, specifically DPA and DHA were negatively associated with DR incidence. This suggests that omega-3 may be a potential protective factor for DR and may help to prevent or delay the onset and progression of DR.

Retinal thickness changes in preobese and obese patients without hyperglycemia: Optical coherence tomography study

PURPOSE

To evaluate retinal thickness changes by optical coherence tomography in preobese and obese patients without hyperglycemia.

METHODS

This comparative cross-sectional study was conducted on 55 normal (18.5-24.9 kg/m2), 42 preobese (25-29.9 kg/m2), 34 obese (>30 kg/m2), a total of 131, according to body mass index (BMI) value at the time of examination. All participants were examined in the internal medicine department and fasting serological biochemical and lipid tests were performed, and those with hyperglycemia were excluded from the study. All participants underwent a full ophthalmological examination and sectoral examination of the retina with optical coherence tomography.

RESULTS

The study included 55 right eyes of 55 normal, 42 of 42 preobese, and 34 of 34 obese, age- and sex-matched participants, without hyperglycemia. The mean BMI of the normal group was 22.3 ± 1.3, 26.8 ± 1.3 in the preobese group, and 33.2 ± 4.2 in the obese group. Central foveal thickness (normal 229.8 ± 20.1 µm, preobese 234.7 ± 18.8 µm and obese 222.0 ± 23.4 µm, P:0.031) and mean inferior (normal 280.7 ± 55.8 µm, preobese 296.7 ± 11.1 µm and obese 285.3 ± 9.9 µm) thickness in the 3 mm The Early Treatment Diabetic Retinopathy Study (ETDRS) circle was significantly higher in the preobese group and significantly lower in the obese group. Mean nasal, temporal, and superior thickness in the 3 mm ETDRS circle and peripapillary retinal nerve fiber layer was higher in the preobese group and lower in the obese group but this difference was statistically not significant.

CONCLUSION

The fact that preobesity, which is not accompanied by hyperglycemia, causes an increase in the thickness of the central macular regions and obesity causes thinning of the retina, supports that lipid metabolism in the body alone can affect retinal thickness changes and retinal neurodegeneration.

Progress and challenges in intravesical drug delivery

INTRODUCTION

Intravesical drug delivery (IDD) has gained recognition as a viable approach for treating bladder-related diseases over the years. However, it comes with its set of challenges, including voiding difficulties and limitations in mucosal and epithelial penetration. These challenges lead to drug dilution and clearance, resulting in poor efficacy. Various strategies for drug delivery have been devised to overcome these issues, all aimed at optimizing drug delivery. Nevertheless, there has been minimal translation to clinical settings.

AREAS COVERED

This review provides a detailed description of IDD, including its history, advantages, and challenges. It also explores the physical barriers encountered in IDD, such as voiding, mucosal penetration, and epithelial penetration, and discusses current strategies for overcoming these challenges. Additionally, it offers a comprehensive roadmap for advancing IDD into clinical trials.

EXPERT OPINION

Physical bladder barriers and limitations of conventional treatments result in unsatisfactory efficacy against bladder diseases. Nevertheless, substantial recent efforts in this field have led to significant progress in overcoming these challenges and have raised important attributes for an optimal IDD system. However, there is still a lack of well-defined steps in the workflow to optimize the IDD system for clinical settings, and further research is required to establish more comprehensive in vitro and in vivo models to expedite clinical translation.

Metabolites as Risk Factors for Diabetic Retinopathy in Patients With Type 2 Diabetes: A 12-Year Follow-up Study

CONTEXT

Diabetic retinopathy (DR) is a specific microvascular complication in patients with diabetes and the leading cause of blindness. Recent advances in omics, especially metabolomics, offer the possibility identifying novel potential biomarkers for DR.

OBJECTIVE

The aim was to identify metabolites associated with DR.

METHODS

We performed a 12-year follow-up study including 1349 participants with type 2 diabetes (1021 without DR, 328 with DR) selected from the METSIM cohort. Individuals who had retinopathy before the baseline study were excluded (n = 63). The diagnosis of retinopathy was based on fundus photography examination. We performed nontargeted metabolomics profiling to identify metabolites.

RESULTS

We found 17 metabolites significantly associated with incident DR after adjustment for confounding factors. Among amino acids, N-lactoyl isoleucine, N-lactoyl valine, N-lactoyl tyrosine, N-lactoyl phenylalanine, N-(2-furoyl) glycine, and 5-hydroxylysine were associated with an increased risk of DR, and citrulline with a decreased risk of DR. Among the fatty acids N,N,N-trimethyl-5-aminovalerate was associated with an increased risk of DR, and myristoleate (14:1n5), palmitoleate (16:1n7), and 5-dodecenoate (12:1n7) with a decreased risk of DR. Sphingomyelin (d18:2/24:2), a sphingolipid, was significantly associated with a decreased risk of DR. Carboxylic acid maleate and organic compounds 3-hydroxypyridine sulfate, 4-vinylphenol sulfate, 4-ethylcatechol sulfate, and dimethyl sulfone were significantly associated with an increased risk of DR.

CONCLUSION

Our study is the first large population-based longitudinal study to identify metabolites for DR. We found multiple metabolites associated with an increased and decreased risk for DR from several different metabolic pathways.

Mendelian Randomization Analysis Reveals Causal Effects of Polyunsaturated Fatty Acids on Subtypes of Diabetic Retinopathy Risk

Polyunsaturated fatty acids (PUFAs) affect several physiological processes, including visual acuity, but their relationship with diabetic retinopathy (DR) remains elusive. The aim of this study was to determine whether PUFAs have a causal effect on DR. PUFAs- (total and omega-3 [FAw3] and omega-6 [FAw6] fatty acids and their ratio) and DR-associated single nucleotide polymorphisms derived from genome-wide association studies; sample sizes were 114,999 for fatty acids and 216,666 for any DR (ADR), background DR (BDR), severe non-proliferative DR (SNPDR), and proliferative DR (PDR). We hypothesized that the intra-body levels of PUFAs have an impact on DR and conducted a two-sample Mendelian randomization (MR) study to assess the causality. Pleiotropy, heterogeneity, and sensitivity analyses were performed to verify result reliability. High levels of PUFAs were found to be associated with reduced risk of both ADR and PDR. Moreover, FAw3 was associated with a decreased risk of PDR, whereas FAw6 demonstrated an association with lowered risks of both BDR and PDR. Our findings provide genetic evidence, for the first time, for a causal relationship between PUFAs and reduced DR risk. Consequently, our comprehensive MR analysis strongly urges further investigation into the precise functions and long-term effects of PUFAs, FAw3, and FAw6 on DR.

Pharmacotherapy and Nutritional Supplements for Neovascular Eye Diseases

In this review, we aim to provide an overview of the recent findings about the treatment of neovascular retinal diseases. The use of conventional drugs and nutraceuticals endowed with antioxidant and anti-inflammatory properties that may support conventional therapies will be considered, with the final aim of achieving risk reduction (prevention) and outcome improvement (cooperation between treatments) of such sight-threatening proliferative retinopathies. For this purpose, we consider a medicinal product one that contains well-defined compound(s) with proven pharmacological and therapeutic effects, usually given for the treatment of full-blown diseases. Rarely are prescription drugs given for preventive purposes. A dietary supplement refers to a compound (often an extract or a mixture) used in the prevention or co-adjuvant treatment of a given pathology. However, it must be kept in mind that drug-supplement interactions may exist and might affect the efficacy of certain drug treatments. Moreover, the distinction between medicinal products and dietary supplements is not always straightforward. For instance, melatonin is formulated as a medicinal product for the treatment of sleep and behavioral problems; at low doses (usually below 1 mg), it is considered a nutraceutical, while at higher doses, it is sold as a psychotropic drug. Despite their lower status with respect to drugs, increasing evidence supports the notion of the beneficial effects of dietary supplements on proliferative retinopathies, a major cause of vision loss in the elderly. Therefore, we believe that, on a patient-by-patient basis, the administration of nutraceuticals, either alone or in association, could benefit many patients, delaying the progression of their disease and likely improving the efficacy of pharmaceutical drugs.

Pro-Inflammatory diet accounts for higher prevalence of retinopathy in diabetes participants rather than normal glucose and prediabetes: Results from NHANES, 2005-2008

Retinopathy is a chronic inflammatory disease whose prognosis could be improved with dietary interventions. However, the association between a pro-inflammatory diet and the prevalence of retinopathy has not been fully elucidated. We assess the association between the dietary inflammatory index (DII), which is a comprehensive index determining inflammatory potential derived from food parameters according to literature, and the prevalence of retinopathy based on the data from the National Health and Nutritional Examination Survey (NHANES) 2005-2008 involving 2,403 participants. Energy-adjusted DII (E-DII) was not related to the occurrence of retinopathy in the general, non-diabetic, or middle-aged participants. In the diabetic and aged participants, one unit increment of E-DII accounted for 14 and 15% higher the prevalence of retinopathy respectively. The highest E-DII group had a 78 and 79% higher prevalence of retinopathy than the lowest group respectively. After adjusting for several covariables, the highest E-DII group was still associated with a 68% increase in retinopathy in diabetic patients. These results suggest that E-DII is positively associated with the prevalence of diabetic retinopathy among diabetic patients.

The role of retinal Müller cells in diabetic retinopathy and related therapeutic advances

Diabetic retinopathy (DR) is a significant complication of diabetes. During the pathogenesis of retinal microangiopathy and neuronopathy, activated retinal Müller cells (RMCs) undergo morphological and structural changes such as increased expression of glial fibrillary acidic protein, disturbance of potassium and water transport regulation, and onset of production of a large number of inflammatory and vascular growth factors as well as chemokines. Evidently, activated RMCs are necessary for the pathogenesis of DR; therefore, exploring the role of RMCs in DR may provide a new target for the treatment thereof. This article reviews the mechanism of RMCs involvement in DR and the progress in related treatments.

Th22 cells induce Müller cell activation via the Act1/TRAF6 pathway in diabetic retinopathy

T helper 22 (Th22) cells have been implicated in diabetic retinopathy (DR), but it remains unclear whether Th22 cells involve in the pathogenesis of DR. To investigate the role of Th22 cells in DR mice, the animal models were established by intraperitoneal injection of STZ and confirmed by fundus fluorescein angiography and retinal haematoxylin-eosin staining. IL-22BP was administered by intravitreal injection. IL-22 level was measured by ELISA in vivo and in vitro. The expression of IL-22Rα1 in the retina was assessed by immunofluorescence. We assessed GFAP, VEGF, ICAM-1, inflammatory-associated factors and the integrity of blood-retinal barrier in control, DR, IL-22BP, and sham group. Müller cells were co-cultured with Th22 cells, and the expression of the above proteins was measured by immunoblotting. Plasmid transfection technique was used to silence Act1 gene in Müller cells. Results in vivo and in vitro indicated that Th22 cells infiltrated into the DR retinal and IL-22Rα1 expressed in Müller cells. Th22 cells promoted Müller cells activation and inflammatory factor secretion by secreting IL-22 compared with high-glucose stimulation alone. In addition, IL-22BP ameliorated the pathological alterations of the retina in DR. Inhibition of the inflammatory signalling cascade through Act1 knockdown alleviated DR-like pathology. All in all, the results suggested that Th22 cells infiltrated into the retina and secreted IL-22 in DR, and then IL-22 binding with IL-22Rα1 activated the Act1/TRAF6 signal pathway, and promoted the inflammatory of Müller cells and involved the pathogenesis of DR.

Optical coherence tomography angiography findings of retinal vascular structures in children with celiac disease

PURPOSE

To investigate the vasculature of the retina and choroid in children with celiac disease using optical coherence tomography angiography (OCTA).

METHODS

A total of 60 children with celiac disease and 71 healthy controls were included in this study. All participants underwent comprehensive ophthalmologic examination and OCTA imaging. The vascular structures and the vascular density (VD) in the superficial and deep retinal vascular zones, the foveal avascular zone (FAZ) and foveal density were automatically determined using the software 3 × 3 OCTA and AngioAnalytics. Choroid thickness was calculated manually by retinal specialists.

RESULTS

No statistically significant difference in VD was found between subjects and controls. The FAZ was larger in the celiac group than in controls (0.306 ± 0.12 mm² vs 0.287 ± 0.11 mm²), but the difference was not statistically significant (P = 0.383). Subfoveal choroid thickness was thinner in the celiac group (309.9 ± 76.97 μm) than in the control group (328 ± 68.51 μm), but the difference was not statistically significant (P = 0.157) CONCLUSIONS: No statistically significant differences in VD, mean FAZ or mean subfoveal choroidal thickness were found in children with CD compared to controls.

Hydroxysafflor yellow A improved retinopathy via Nrf2/HO-1 pathway in rats

The aim of the study was to investigate the inhibitory effect of hydroxysaff yellow A (HSYA) on diabetic retinopathy (DR). For this, a total of 27 rats were randomly divided into normal control, model, and HSYA groups. The body weight, blood glucose, and blood–retinal barrier damage of the rats were observed and compared. The pathological change of retinal tissue were measured using H&E staining. The apoptosis of retinal tissue ganglion cells was detected by TUNEL. The interleukin (IL)-1β and tumor necrosis fator (TNF)-α levels were detected using enzyme-linked immunosorbent assay. The level of malondialdehyde (MDA) was detected using thiobarbituric acid method. Superoxide dismutase levels were detected using xanthine oxidase method; Nrf2 and total HO-1 protein expressions were detected using western blot assay; Bcl-2 and P53 protein expression was measured using immunohistochemical staining. The body weight and retinal damage of the HYSA group were significantly improved (p < 0.01, respectively). The apoptosis index of the HYSA group was lower than the model group (p < 0.001). The IL-1β, TNF-α, and MDA levels of the HYSA group were significantly improved in comparison with those of the model group (p < 0.01, respectively). The Nrf-2, HO-1, Bcl-2, and P53 protein expression of HYSA group was significantly improved (p < 0.001, respectively). In conclusion, HYSA can effectively alleviate the apoptosis of retinal ganglion cells in type 2 diabetic rats and improve the progression of DR.

Diabetic retinopathy and visual impairment in a Norwegian diabetic coast population with a high dietary intake of fish oils. An observational study

PURPOSE

To present retinal and visual findings in a Norwegian west coast diabetic population and to elucidate the effect of dietary intake of marine polyunsaturated fatty acids (PUFAs) on the development of diabetic retinopathy (DR).

METHODS

In an eye practice in an archipelago of 314 km², serving a population of about 40 000, we recorded the prevalence of visual impairment and DR in a referred diabetic population. 510 consecutive patients were included, 238 females and 272 males. 50 patients had type I and 460 had type II diabetes mellitus (DM). Self-reported medication, diet supplements, HbA1c and fish consumption were registered.

RESULTS

In the type I group, the median age was 44.5 and median DM duration 11.5 years [1-44]. 48% had photographic evidence of DR, 8 patients (16%) had proliferative retinopathy (PDR), and 6 patients (12%) had diabetic macular oedema (DME). All had best-corrected visual acuity (BCVA) of 0.5 (log MAR 0.3) or better in the best eye. In the type II group, the median DM duration was 8 years [1-53], and median age was 66. 98% had best eye BCVA at or better than 0.5 (log MAR 0.3) in the best eye.

CONCLUSION

None of the 510 patients had BCVA worse than 0.3 (log MAR 0.48) due to diabetic retinopathy. Compared to similar studies, we found a very low visual impairment rate. A possible protective effect of PUFA on the prevalence and progression of diabetic microangiopathy including retinopathy is discussed.

Cellular targets in diabetic retinopathy therapy

Despite the existence of treatment for diabetes, inadequate metabolic control triggers the appearance of chronic complications such as diabetic retinopathy. Diabetic retinopathy is considered a multifactorial disease of complex etiology in which oxidative stress and low chronic inflammation play essential roles. Chronic exposure to hyperglycemia triggers a loss of redox balance that is critical for the appearance of neuronal and vascular damage during the development and progression of the disease. Current therapies for the treatment of diabetic retinopathy are used in advanced stages of the disease and are unable to reverse the retinal damage induced by hyperglycemia. The lack of effective therapies without side effects means there is an urgent need to identify an early action capable of preventing the development of the disease and its pathophysiological consequences in order to avoid loss of vision associated with diabetic retinopathy. Therefore, in this review we propose different therapeutic targets related to the modulation of the redox and inflammatory status that, potentially, can prevent the development and progression of the disease.

The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms

We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.

Role of Oral Antioxidant Supplementation in the Current Management of Diabetic Retinopathy

Oxidative stress has been postulated as an underlying pathophysiologic mechanism of diabetic retinopathy (DR), the main cause of avoidable blindness in working-aged people. This review addressed the current daily clinical practice of DR and the role of antioxidants in this practice. A systematic review of the studies on antioxidant supplementation in DR patients was presented. Fifteen studies accomplished the inclusion criteria. The analysis of these studies concluded that antioxidant supplementation has a IIB level of recommendation in adult Type 1 and Type 2 diabetes mellitus subjects without retinopathy or mild-to-moderate nonproliferative DR without diabetic macular oedema as a complementary therapy together with standard medical care.

A Randomized Study of Nutritional Supplementation in Patients with Unilateral Wet Age-Related Macular Degeneration

The purpose of this study is evaluate the efficacy and safety of medicinal products containing the original Age-Related Eye Disease group (AREDS) formulation at doses approved in Europe (EU, control group; n = 59) with a product that adds DHA, lutein, zeaxanthin, resveratrol and hydroxytyrosol to the formula (intervention group; n = 50). This was a multicenter, randomized, observer-blinded trial conducted in patients aged 50 years or older diagnosed with unilateral exudative Age related Macular Degeneration AMD. At month 12, the intervention did not have a significant differential effect on visual acuity compared with the control group, with an estimated treatment difference in Early Treatment Diabetic Retinopathy Study (ETDRS) of −1.63 (95% CI −0.83 to 4.09; p = 0.192). The intervention exhibited a significant and, in most cases, relevant effect in terms of a reduction in some inflammatory cytokines and a greater improvement in the fatty acid profile and serum lutein and zeaxantin concentration. In patients with unilateral wet AMD, the addition of lutein, zeaxanthin, resveratrol, hydroxytyrosol and DHA to the AREDS EU recommended doses in the short-term did not have a differential effect on visual acuity compared to a standard AREDS EU formula but, in addition to improving the fatty acid profile and increasing carotenoid serum levels, may provide a beneficial effect in improving the proinflammatory and proangiogenic profile of patients with AMD.

Plasma fatty acids and primary open-angle glaucoma in the elderly: the Montrachet population-based study

Background

To compare plasma fatty acids (FAs) between participants with primary open-angle glaucoma (POAG) and participants without neuropathy in an elderly population and to investigate specific FAs pattern in POAG.

Methods

We conducted a population-based study in participants older than 75 years. Participants underwent a comprehensive eye examination with optic nerve photographs, visual field test and optic nerve OCT with RNFL thickness measurement. Glaucomatous status was defined according to the International Society for Epidemiologic and Geographical Ophthalmology classification. Lipids were extracted from plasma and FAs methylesters prepared and analyzed by gas chromatography-mass spectrometry.

Results

Among the 1153 participants of the Montrachet study 810 were retained for analysis and 68 had POAG. The mean age was 82.11 ± 3.67. In multivariable analysis FAs levels were not different between POAG participants and controls (P = 0.078). A FAs pattern characterized by high negative weight of gamma-linoleic acid, eicosapentaenoic acid polyunsaturated FAs (PUFAs), Cis-7 hexadecenoic acid monounsaturated FAs (MUFAs) and high positive weight of eicosadienoic acid, docosatetraenoic acid, docosapentaenoic n-6, alpha linoleic acid PUFAs, eicosenoic acid MUFAs, margaric acid and behenic acid saturated FAs was positively associated with POAG. After adjustment for major confounders, individuals in the upper tertile of FAs pattern scores compared with those in the lower tertile were more likely to present POAG (OR = 3.09 [95% CI 1.29–7.40] P = 0.013).

Conclusions

We found no significant difference regarding isolated plasma FAs between participants with POAG and participants without neuropathy in elderly but specific FAs pattern might be associated with POAG.

Emerging insights into the relationship between hyperlipidemia and the risk of diabetic retinopathy

Hyperlipidemia is correlated with a series of health problems. Notably, aside from its established role in promoting cardiovascular morbidity and mortality, hyperlipidemia has also been considered for modulating the risk and the severity of multiple metabolic disorders. According to the results of epidemiologic investigations, several certain circulating lipoprotein species are correlated with the prevalence of diabetic retinopathy, suggesting that the physiological and pathological role of these lipoproteins is analogous to that observed in cardiovascular diseases. Furthermore, the lipid-lowering treatments, particularly using statin and fibrate, have been demonstrated to ameliorate diabetic retinopathy. Thereby, current focus is shifting towards implementing the protective strategies of diabetic retinopathy and elucidating the potential underlying mechanisms. However, it is worth noting that the relationship between major serum cholesterol species and the development of diabetic retinopathy, published by other studies, was inconsistent and overall modest, revealing the relationship is still not clarified. In this review, the current understanding of hyperlipidemia in pathogenesis of diabetic retinopathy was summarized and the novel insights into the potential mechanisms whereby hyperlipidemia modulates diabetic retinopathy were put forward.

Molecular Basis of the Beneficial Actions of Resveratrol

Resveratrol modulates the transcription factor NF-κB, cytochrome P450 isoenzyme CYP1A1, expression and activity of cyclooxygenase (COX) enzymes, Fas/Fas ligand mediated apoptosis, p53, mTOR and cyclins and various phospho-diesterases resulting in an increase in cytosolic cAMP levels. Cyclic AMP, in turn, activates Epac1/CaMKKβ/AMPK/SIRT1/PGC-1α pathway that facilitates increased oxidation of fatty acids, mitochondrial respiration and their biogenesis and gluconeogenesis. Resveratrol triggers apoptosis of activated T cells and suppresses tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17) and other pro-inflammatory molecules and inhibits expression of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) that may explain its anti-inflammatory actions. Polyunsaturated fatty acids (PUFAs) and their anti-inflammatory metabolites lipoxin A4, resolvins, protectins and maresins have a significant role in obesity, type 2 diabetes mellitus (T2DM), metabolic syndrome and cancer. We observed that PUFAs (especially arachidonic acid, AA) and BDNF (brain-derived neurotrophic factor) protect against the cytotoxic actions of alloxan, streptozotocin, benzo(a)pyrene (BP) and doxorubicin. Thus, there is an overlap in the beneficial actions of resveratrol, PUFAs and BDNF suggesting that these molecules may interact and augment synthesis and action of each other. This is supported by the observation that resveratrol and PUFAs modulate gut microbiota and influence stem cell proliferation and differentiation. Since resveratrol is not easily absorbed from the gut it is likely that it may act on endocannabinoid and light, odor, and taste receptors located in the gut, which, in turn, convey their messages to the various organs via vagus nerve.