Effect of lutein and antioxidant supplementation on VEGF expression, MMP-2 activity, and ultrastructural alterations in apolipoprotein E-deficient mouse

Antioxidants and neurodegenerative eye disease

Neurodegenerative ocular disorders mostly develop with aging and present great complications in the quality of life. Glaucoma and age-related macular degeneration (ARMD) rank as the third and fourth leading causes of blindness and low vision. Oxidative stress is one factor in the pathogenesis of neurodegenerative eye disease. In addition, ocular ischemia and neuroinflammation play an important role. It can be hypothesized that the influence of antioxidants through diet or oral supplementation can counteract the harmful effects of reactive oxygen species accumulated secondary to oxidative stress, ischemia, and inflammation. A range of studies has been published over the past decades focusing on the possible adjuvant effect of antioxidants in ARMD, while there were fewer reports on the potential role of antioxidants in glaucoma. Although certain reports demonstrated positive results, others were discouraging. As there is a controversy between the studies favoring and disfavoring supplementation with different types of antioxidants, it is important to revise the existing evidence on the role of antioxidants in neurodegenerative ocular disorders with a special focus on glaucoma and ARMD.

Clinical management of eye diseases: carotenoids and their nanoformulations as choice of therapeutics

Eye diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR), impose a substantial health cost on a worldwide scale. Carotenoids have emerged as intriguing candidates for pharmacological treatment of various disorders. Their therapeutic effectiveness, however, is hindered by poor solubility and vulnerability to degradation. Nanocarriers, such as nanoparticles, liposomes, and micelles, provide a transformational way to overcome these limits. This review explores the pharmacological potential of carotenoids, namely lutein, zeaxanthin, and astaxanthin, to treat several ocular disorders. The main emphasis is on their anti-inflammatory and antioxidant actions, which help to counteract inflammation and oxidative stress, crucial factors in the development of AMD and DR. The review evaluates the significant benefits of nano-formulated carotenoids, such as improved bioavailability, higher cellular absorption, precise administration to particular ocular tissues, and greater biostability, which make them superior to conventional carotenoids. Some clinical studies on the beneficial properties of carotenoids in eye diseases are discussed. Furthermore, safety and regulatory concerns are also taken into account. Ultimately, carotenoids, especially when created in their nano form, have significant potential for safeguarding eyesight and enhancing the overall well-being of several individuals afflicted with vision-endangering eye diseases.

Prenatal Carotenoid Supplementation With Lutein or Zeaxanthin Ameliorates Oxygen-Induced Retinopathy (OIR) in Bco2-/- Macular Pigment Mice

Purpose

Premature infants at risk of retinopathy of prematurity (ROP) miss placental transfer of the carotenoids lutein (L) and zeaxanthin (Z) during the third trimester. We previously demonstrated that prenatal L and Z supplementation raised carotenoid levels in infants at birth in the Lutein and Zeaxanthin in Pregnancy (L-ZIP) study (NCT03750968). Based on their antioxidant effects and bioavailability, we hypothesized that prenatal maternal supplementation with macular carotenoids would reduce the risk of ROP. To test this hypothesis, we utilized "macular pigment mice" genetically engineered to take up L and Z into the retina in a model of oxygen-induced retinopathy (OIR).

Methods

Pregnant Bco2-/- mice were divided into nine experimental subgroups based on the type of supplementation (L, Z, or placebo) and on the maternal supplementation start date corresponding to the three trimesters of human fetal development (E0, E11, and P1). Pups and nursing mothers were exposed to 75% O2 for 5 days (P7-P12) and returned to room air for 5 days (P12-P17). Pups were killed at P12 and P17, and their retinas were analyzed for vaso-obliteration and intravitreal neovascularization.

Results

Pups of pregnant mice supplemented with L or Z had significant reductions in areas of vaso-obliteration and intravitreal neovascularization compared to placebo. Prenatal carotenoid supplementation starting at E0 or E11 was significantly more protective against OIR than postnatal supplementation starting at P1.

Conclusions

Prenatal supplementation with L and Z was beneficial in a mouse OIR model. We recommend testing prenatal L and Z supplementation in future human clinical trials to prevent ROP.

Inherited Retinal Dystrophies: Role of Oxidative Stress and Inflammation in Their Physiopathology and Therapeutic Implications

Inherited retinal dystrophies (IRDs) are a large group of genetically and clinically heterogeneous diseases characterized by the progressive degeneration of the retina, ultimately leading to loss of visual function. Oxidative stress and inflammation play fundamental roles in the physiopathology of these diseases. Photoreceptor cell death induces an inflammatory state in the retina. The activation of several molecular pathways triggers different cellular responses to injury, including the activation of microglia to eliminate debris and recruit inflammatory cells from circulation. Therapeutical options for IRDs are currently limited, although a small number of patients have been successfully treated by gene therapy. Many other therapeutic strategies are being pursued to mitigate the deleterious effects of IRDs associated with oxidative metabolism and/or inflammation, including inhibiting reactive oxygen species’ accumulation and inflammatory responses, and blocking autophagy. Several compounds are being tested in clinical trials, generating great expectations for their implementation. The present review discusses the main death mechanisms that occur in IRDs and the latest therapies that are under investigation.

Tissue-Specific Gamma-Flicker Light Noninvasively Ameliorates Retinal Aging

Aging is a risk factor for multiple retinal degeneration diseases. Entraining brain gamma oscillations with gamma-flicker light (γFL) has been confirmed to coordinate pathological changes in several Alzheimer's disease mouse models and aged mice. However, the direct effect of γFL on retinal aging remains unknown. We assessed retinal senescence-associated beta-galactosidase (β-gal) and autofluorescence in 20-month-old mice and found reduced β-gal-positive cells in the inner retina and diminished lipofuscin accumulation around retinal vessels after 6 days of γFL. In immunofluorescence, γFL was further demonstrated to ameliorate aging-related retinal changes, including a decline in microtubule-associated protein 1 light chain 3 beta expression, an increase in complement C3 activity, and an imbalance between the anti-oxidant factor catalase and pro-oxidant factor carboxymethyl lysine. Moreover, we found that γFL can increase the expression of activating transcription factor 4 (ATF4) in the inner retina, while revealing a decrease of ATF4 expression in the inner retina and positive expression in the outer segment of photoreceptor and RPE layer for aged mice. Western blotting was then used to confirm the immunofluorescence results. After mRNA sequencing (NCBI Sequence Read Archive database: PRJNA748184), we found several main mechanistic clues, including mitochondrial function and chaperone-mediated protein folding. Furthermore, we extended γFL to aged Apoe^-/- mice and showed that 1-m γFL treatment even improved the structures of retinal-pigment-epithelium basal infolding and Bruch's membrane. Overall, γFL can orchestrate various pathological characteristics of retinal aging in mice and might be a noninvasive, convenient, and tissue-specific therapeutic strategy for retinal aging.

Changes in Retinal Structure and Ultrastructure in the Aged Mice Correlate With Differences in the Expression of Selected Retinal miRNAs

Age and gender are two important factors that may influence the function and structure of the retina and its susceptibility to retinal diseases. The aim of this study was to delineate the influence that biological sex and age exert on the retinal structural and ultrastructural changes in mice and to identify the age-related miRNA dysregulation profiles in the retina by gender. Experiments were undertaken on male and female Balb/c aged 24 months (approximately 75–85 years in humans) compared to the control (3 months). The retinas were analyzed by histology, transmission electron microscopy, and age-related miRNA expression profile analysis. Retinas of both sexes showed a steady decline in retinal thickness as follows: photoreceptor (PS) and outer layers (p < 0.01 for the aged male vs. control; p < 0.05 for the aged female vs. control); the inner retinal layers were significantly affected by the aging process in the males (p < 0.01) but not in the aged females. Electron microscopy revealed more abnormalities which involve the retinal pigment epithelium (RPE) and Bruch’s membrane, outer and inner layers, vascular changes, deposits of amorphous materials, and accumulation of lipids or lipofuscins. Age-related miRNAs, miR-27a-3p (p < 0.01), miR-27b-3p (p < 0.05), and miR-20a-5p (p < 0.05) were significantly up-regulated in aged male mice compared to the controls, whereas miR-20b-5p was significantly down-regulated in aged male (p < 0.05) and female mice (p < 0.05) compared to the respective controls. miR-27a-3p (5.00 fold; p < 0.01) and miR-27b (7.58 fold; p < 0.01) were significantly up-regulated in aged male mice vs. aged female mice, whereas miR-20b-5p (−2.10 fold; p < 0.05) was significantly down-regulated in aged male mice vs. aged female mice. Interestingly, miR-27a-3p, miR-27b-3p, miR-20a-5p, and miR-20b-5p expressions significantly correlated with the thickness of the retinal PS layer (p < 0.01), retinal outer layers (p < 0.01), and Bruch’s membrane (p < 0.01). Our results showed that biological sex can influence the structure and function of the retina upon aging, suggesting that this difference may be underlined by the dysregulation of age-related mi-RNAs.

Long-term lutein administration attenuates retinal inflammation and functional deficits in early diabetic retinopathy using the Ins2Akita/+ mice

INTRODUCTION

Lutein is a carotenoid whose protective effects in the retina have been reported in various studies. The effect of lutein has not been reported in the retina of the Ins2^Akita/+ mouse, a well-characterized genetic model for diabetic retinopathy (DR) in which the etiology of diabetes is better defined than the chemically induced diabetes. The objective of the present study is to investigate the effect of long-term administration of lutein in early stages of DR using the Ins2^Akita/+ mouse.

RESEARCH DESIGN AND METHODS

Heterozygous male Ins2^Akita/+ and age-matched wild-type mice were used. Lutein was administered to the mice in drinking water starting 6 weeks old daily until analysis at 4.5, 6.5 or 9 months of age. Plain water served as non-treatment control. Microglia were immunostained with ionized calcium-binding adapter molecule 1 (Iba-1) and cluster of differentiation 68 (CD68) in retinal flat-mounts. Vascular endothelial growth factor (VEGF) level in the retina was assessed by enzyme-linked immunosorbent assay (ELISA). Vascular permeability was analyzed in retinal flat-mounts after fluorescein isothiocyanate (FITC)-dextran perfusion. Retinal occludin expression was assessed via Western blots. Retinal function was examined by electroretinography (ERG).

RESULTS

Increased microglial reactivity was detected in the Ins2^Akita/+ mouse retina and was suppressed by lutein. Lutein administration also reduced the upregulation of VEGF in the Ins2^Akita/+ mouse retina. Increased vascular leakage and decreased occludin expression were observed in the Ins2^Akita/+ mouse retina, and these alterations were attenuated by lutein treatment. ERG recordings showed reduced a-wave and b-wave amplitudes in the Ins2^Akita/+ mice. With lutein treatment, the ERG deficits were significantly alleviated.

CONCLUSIONS

We showed beneficial effects of long-term lutein administration in the Ins2^Akita/+ mouse retina, including suppression of retinal inflammation, protection of retinal vasculature and preservation of retinal function. These results point to lutein's potential as a long-term therapeutic intervention for prevention of inflammation and retinal degeneration in patients with early DR.

Lutein Supplementation for Eye Diseases

Lutein is one of the few xanthophyll carotenoids that is found in high concentration in the macula of human retina. As de novo synthesis of lutein within the human body is impossible, lutein can only be obtained from diet. It is a natural substance abundant in egg yolk and dark green leafy vegetables. Many basic and clinical studies have reported lutein's anti-oxidative and anti-inflammatory properties in the eye, suggesting its beneficial effects on protection and alleviation of ocular diseases such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, myopia, and cataract. Most importantly, lutein is categorized as Generally Regarded as Safe (GRAS), posing minimal side-effects upon long term consumption. In this review, we will discuss the chemical structure and properties of lutein as well as its application and safety as a nutritional supplement. Finally, the effects of lutein consumption on the aforementioned eye diseases will be reviewed.

Efficacy of Terpenoid in Attenuating Aortic Atherosclerosis in Apolipoprotein-E Deficient Mice: A Meta-Analysis of Animal Studies

Background

The apolipoprotein E knockout (ApoE -/-) mouse model is well established for the study of terpenoids in the prevention of atherosclerosis. Studies investigating the clinical benefit of terpenoids in humans are scarce. This systematic review and meta-analysis evaluated the effects of terpenoid administration on atherosclerotic lesion area in ApoE -/- mice.

Methods

A comprehensive literature search using PubMed, Embase, and the Cochrane Library databases was performed to identify studies that assessed the effects of terpenoids on atherosclerosis in ApoE -/- mice. The primary outcome was atherosclerotic lesion area, and study quality was estimated using SYRCLE's risk of bias tool.

Results

The meta-analysis included 25 studies. Overall, terpenoids significantly reduced atherosclerotic lesion area when compared to vehicle control (P<0.00001; SMD: -0.55; 95% CI: -0.72, -0.39). In terpenoid type and dose subgroup analyses, sesquiterpenoid (P=0.002; SMD -0.93; 95% CI: -1.52, -0.34), diterpenoid (P=0.01; SMD: -0.30; 95% CI: -0.54, -0.06), triterpenoid (P<0.00001; SMD: -0.66; 95% CI: -0.94, -0.39), tetraterpenoid (P<0.0001; SMD: -1.81; 95% CI: -2.70, -0.91), low dose (P=0.0001; SMD: -0.51; 95% CI: -0.76, -0.25), medium dose (P<0.0001; SMD: -0.48; 95% CI: -0.72, -0.24), and high dose (P=0.002; SMD: -1.07; 95% CI: -1.74, -0.40) significantly decreased atherosclerotic lesion area when compared to vehicle control. PROSPERO register number is CRD42019121176.

Conclusion

Sesquiterpenoid, diterpenoid, triterpenoid, and tetraterpenoid have potential as antiatherosclerotic agents with a wide range of doses. This systematic review provides a reference for research programs aimed at the development of terpenoid-based clinical drugs.

Supplementation with macular carotenoids improves visual performance of transgenic mice

Carotenoid supplementation can improve human visual performance, but there is still no validated rodent model to test their effects on visual function in laboratory animals. We recently showed that mice deficient in β-carotene oxygenase 2 (BCO2) and/or β-carotene oxygenase 1 (BCO1) enzymes can accumulate carotenoids in their retinas, allowing us to investigate the effects of carotenoids on the visual performance of mice. Using OptoMotry, a device to measure visual function in rodents, we examined the effect of zeaxanthin, lutein, and β-carotene on visual performance of various BCO knockout mice. We then transgenically expressed the human zeaxanthin-binding protein GSTP1 (hGSTP1) in the rods of bco2^-/- mice to examine if delivering more zeaxanthin to retina will improve their visual function further. The visual performance of bco2^-/- mice fed with zeaxanthin or lutein was significantly improved relative to control mice fed with placebo beadlets. β-Carotene had no significant effect in bco2^-/- mice but modestly improved cone visual function of bco1^-/- mice. Expression of hGSTP1 in the rods of bco2^-/-mice resulted in a 40% increase of retinal zeaxanthin and further improvement of visual performance. This work demonstrates that these "macular pigment mice" may serve as animal models to study carotenoid function in the retina.

Mortality after endovascular treatment of infrarenal abdominal aortic aneurysms – the newer the better?

Abstract. Although endovascular repair of infrarenal abdominal aortic aneurysms (EVAR) presents a delicate alternative treatment for abdominal aortic aneurysms (AAA) with lower perioperative mortality, its long-term efficacy remains a matter of concern. The purpose of this study was to evaluate the currently reported mortality evidence after EVAR and to examine the possible effect of aneurysm status and the study period on mortality rates. The PubMed and Cochrane bibliographical databases were thoroughly searched for studies reporting on more than 1 000 patients with non-ruptured or ruptured infrarenal AAA, treated with EVAR from August 1991 to September 2016. A total of 10 910 titles/abstracts were retrieved and 121 studies were deemed relevant. Twenty-six studies met the inclusion criteria and reported on 354 500 patients with a mean age of 74.6 years. Almost all of the studies referred to elective EVAR and the mean aneurysm size was 5.58 cm. The most common early complication for elective EVAR was perioperative bleeding (1.9 %), whereas hospital-acquired pneumonia was a major concern in urgent EVAR (28.5 %). Conversion rate to open surgery was 1.2 %. The 30-day all-cause mortality rate was 4.84 % (1.7 % for non- ruptured aneurysms, 33.8 % for ruptured aneurysms).The overall all-cause late mortality in a mean follow-up period of 23.8 months was 19.1 %. The aneurysm-related late mortality rate was 3.4 %. With respect to the time period of patient enrollment, studies reporting on patients recruited before 2006 were found to face more secondary complications and higher late mortality rates than patients enrolled after 2005.The endovascular treatment of large and anatomically suitable infrarenal AAA in selected patients remains a safe alternative to open repair. Our findings demonstrate that newer studies show better long-term outcomes than the older ones, proposing a possible improvement of EVAR techniques and perioperative care and providing encouraging evidence for a wider application of EVAR.

Lutein and zeaxanthin isomers modulates lipid metabolism and the inflammatory state of retina in obesity-induced high-fat diet rodent model

Background

Several studies associated high-fat intakes with a high incidence of age-related macular degeneration (AMD). Lutein and Zeaxanthin isomers (L/Zi) may counteract reactive oxygen species produced by oxidative stress. The present study was conducted to determine the possible effects of L/Zi administration on lipid profile, protein genes associated with oxidative stress and inflammation pathways in the obesity induced by a high-fat diet (HFD) in rodents.

Methods

Twenty-eight male Wistar rats were allocated into four groups as follows: (i) Control, (ii) Control + L/Zi, (iii) High Fat Diet (HFD), and (iv) HFD+ L/Z. L/Zi was administrated for 8 weeks at a daily dose of 100 mg/kg BW.

Results

L/Zi administration significantly reduced insulin and free fatty acid (FFA) levels (P < 0.001) and ameliorated the oxidative damage by reducing malondialdehyde (MDA) concentration and increasing antioxidant enzymes activities of retina induced by HFD. In addition, supplementation decreased the levels of vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-κB) and intercellular adhesion molecule-1 (ICAM) (P < 0.001, respectively) and improved nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) gene proteins in retinal tissues (P < 0.001).

Conclusion

Rats fed with HFD exhibited increased oxidative stress and upregulation of inflammatory indicators. However, L/Zi supplementation modulates genes involved oxidative stress and inflammation including NF-κB and Nrf2 signaling pathways in the retina which may contribute to ameliorating retinal damage induced by HFD.

Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure

The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased "screen time" (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months' supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST. Forty-eight healthy young adults with at least 6 h of daily near-field ST exposure participated in this placebo-controlled trial. Visual performance measures included contrast sensitivity, critical flicker fusion, disability glare, and photostress recovery. Physical indicators of excessive screen time and sleep quality were assessed via questionnaire. MP optical density (MPOD) was assessed via heterochromatic flicker photometry. At baseline, MPOD was correlated significantly with all visual performance measures (p < 0.05 for all). MC supplementation (24 mg daily) yielded significant improvement in MPOD, overall sleep quality, headache frequency, eye strain, eye fatigue, and all visual performance measures, versus placebo (p < 0.05 for all). Increased MPOD significantly improves visual performance and, in turn, improves several undesirable physical outcomes associated with excessive ST. The improvement in sleep quality was not directly related to increases in MPOD, and may be due to systemic reduction in oxidative stress and inflammation.

The Pharmacological Effects of Lutein and Zeaxanthin on Visual Disorders and Cognition Diseases

Lutein (L) and zeaxanthin (Z) are dietary carotenoids derived from dark green leafy vegetables, orange and yellow fruits that form the macular pigment of the human eyes. It was hypothesized that they protect against visual disorders and cognition diseases, such as age-related macular degeneration (AMD), age-related cataract (ARC), cognition diseases, ischemic/hypoxia induced retinopathy, light damage of the retina, retinitis pigmentosa, retinal detachment, uveitis and diabetic retinopathy. The mechanism by which they are involved in the prevention of eye diseases may be due their physical blue light filtration properties and local antioxidant activity. In addition to their protective roles against light-induced oxidative damage, there are increasing evidences that L and Z may also improve normal ocular function by enhancing contrast sensitivity and by reducing glare disability. Surveys about L and Z supplementation have indicated that moderate intakes of L and Z are associated with decreased AMD risk and less visual impairment. Furthermore, this review discusses the appropriate consumption quantities, the consumption safety of L, side effects and future research directions.

Retinal accumulation of zeaxanthin, lutein, and β-carotene in mice deficient in carotenoid cleavage enzymes

Carotenoid supplementation can prevent and reduce the risk of age-related macular degeneration (AMD) and other ocular disease, but until now, there has been no validated and well-characterized mouse model which can be employed to investigate the protective mechanism and relevant metabolism of retinal carotenoids. β-Carotene oxygenases 1 and 2 (BCO1 and BCO2) are the only two carotenoid cleavage enzymes found in animals. Mutations of the bco2 gene may cause accumulation of xanthophyll carotenoids in animal tissues, and BCO1 is involved in regulation of the intestinal absorption of carotenoids. To determine whether or not mice deficient in BCO1 and/or BCO2 can serve as a macular pigment mouse model, we investigated the retinal accumulation of carotenoids in these mice when fed with zeaxanthin, lutein, or β-carotene using an optimized carotenoid feeding method. HPLC analysis revealed that all three carotenoids were detected in sera, livers, retinal pigment epithelium (RPE)/choroids, and retinas of all of the mice, except that no carotenoid was detectable in the retinas of wild type (WT) mice. Significantly higher amounts of zeaxanthin and lutein accumulated in the retinas of BCO2 knockout (bco2^-/-) mice and BCO1/BCO2 double knockout (bco1^-/-/bco2^-/-) mice relative to BCO1 knockout (bco1^-/-) mice, while bco1^-/- mice preferred to take up β-carotene. The levels of zeaxanthin and lutein were higher than β-carotene levels in the bco1^-/-/bco2^-/- retina, consistent with preferential uptake of xanthophyll carotenoids by retina. Oxidative metabolites were detected in mice fed with lutein or zeaxanthin but not in mice fed with β-carotene. These results indicate that bco2^-/- and bco1^-/-/bco2^-/- mice could serve as reasonable non-primate models for macular pigment function in the vertebrate eye, while bco1^-/- mice may be more useful for studies related to β-carotene.

Apolipoprotein E Mimetic Peptide Increases Cerebral Glucose Uptake by Reducing Blood-Brain Barrier Disruption after Controlled Cortical Impact in Mice: An 18F-Fluorodeoxyglucose PET/CT Study

Traumatic brain injury (TBI) disrupts the blood-brain barrier (BBB) and reduces cerebral glucose uptake. Vascular endothelial growth factor (VEGF) is believed to play a key role in TBI, and COG1410 has demonstrated neuroprotective activity in several models of TBI. However, the effects of COG1410 on VEGF and glucose metabolism following TBI are unknown. The current study aimed to investigate the expression of VEGF and glucose metabolism effects in C57BL/6J male mice subjected to experimental TBI. The results showed that controlled cortical impact (CCI)-induced vestibulomotor deficits were accompanied by increases in brain edema and the expression of VEGF, with a decrease in cerebral glucose uptake. COG1410 treatment significantly improved vestibulomotor deficits and glucose uptake and produced decreases in VEGF in the pericontusion and ipsilateral hemisphere of injury, as well as in brain edema and neuronal degeneration compared with the control group. These data support that COG1410 may have potential as an effective drug therapy for TBI.

Lutein, zeaxanthin, and meso-zeaxanthin: The basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease

The human macula uniquely concentrates three carotenoids: lutein, zeaxanthin, and meso-zeaxanthin. Lutein and zeaxanthin must be obtained from dietary sources such as green leafy vegetables and orange and yellow fruits and vegetables, while meso-zeaxanthin is rarely found in diet and is believed to be formed at the macula by metabolic transformations of ingested carotenoids. Epidemiological studies and large-scale clinical trials such as AREDS2 have brought attention to the potential ocular health and functional benefits of these three xanthophyll carotenoids consumed through the diet or supplements, but the basic science and clinical research underlying recommendations for nutritional interventions against age-related macular degeneration and other eye diseases are underappreciated by clinicians and vision researchers alike. In this review article, we first examine the chemistry, biochemistry, biophysics, and physiology of these yellow pigments that are specifically concentrated in the macula lutea through the means of high-affinity binding proteins and specialized transport and metabolic proteins where they play important roles as short-wavelength (blue) light-absorbers and localized, efficient antioxidants in a region at high risk for light-induced oxidative stress. Next, we turn to clinical evidence supporting functional benefits of these carotenoids in normal eyes and for their potential protective actions against ocular disease from infancy to old age.

Management of Ocular Diseases Using Lutein and Zeaxanthin: What Have We Learned from Experimental Animal Studies?

Zeaxanthin and lutein are two carotenoid pigments that concentrated in the retina, especially in the macula. The effects of lutein and zeaxanthin on the prevention and treatment of various eye diseases, including age-related macular degeneration, diabetic retinopathy and cataract, ischemic/hypoxia induced retinopathy, light damage of the retina, retinitis pigmentosa, retinal detachment, and uveitis, have been studied in different experimental animal models. In these animal models, lutein and zeaxanthin have been reported to have beneficial effects in protecting ocular tissues and cells (especially the retinal neurons) against damage caused by different etiological factors. The mechanisms responsible for these effects of lutein and zeaxanthin include prevention of phototoxic damage by absorption of blue light, reduction of oxidative stress through antioxidant activity and free radical scavenging, and their anti-inflammatory and antiangiogenic properties. The results of these experimental animal studies may provide new preventive and therapeutic procedures for clinical management of various vision-threatening diseases.

Modifying Choroidal Neovascularization Development with a Nutritional Supplement in Mice

We examined the effect of nutritional supplements (modified Age Related Eye Disease Study (AREDS)-II formulation containing vitamins, minerals, lutein, resveratrol, and omega-3 fatty acids) on choroidal neovascularization (CNV). Supplements were administered alone and combined with intravitreal anti-VEGF in an early-CNV (diode laser-induced) murine model. Sixty mice were evenly divided into group V (oral vehicle, intravitreal saline), group S (oral supplement, intravitreal saline), group V + aVEGF (oral vehicle, intravitreal anti-VEGF), and group S + aVEGF (oral supplement, intravitreal anti-VEGF). Vehicle and nutritional supplements were administered daily for 38 days beginning 10 days before laser. Intravitreal injections were administered 48 h after laser. Fluorescein angiography (FA) and flat-mount CD31 staining evaluated leakage and CNV lesion area. Expression of VEGF, MMP-2 and MMP-9 activity, and NLRP3 were evaluated with RT-PCR, zymography, and western-blot. Leakage, CNV size, VEGF gene and protein expression were lower in groups V + aVEGF, S + aVEGF, and S than in V (all p < 0.05). Additionally, MMP-9 gene expression differed between groups S + aVEGF and V (p < 0.05) and MMP-9 activity was lower in S + aVEGF than in V and S (both p < 0.01). Levels of MMP-2 and NLRP3 were not significantly different between groups. Nutritional supplements either alone or combined with anti-VEGF may mitigate CNV development and inhibit retinal disease involving VEGF overexpression and CNV.

Oxidative stress and histological changes in a model of retinal phototoxicity in rabbits

Photochemical damage occurs after an exposure to high energy radiation within the visible spectrum of light, causing morphological changes in the retina and the formation of superoxide anion. In this study we created a model of phototoxicity in rabbits. Animals were exposed to a light source for 120 minutes and were sacrificed immediately or one week after exposure. Outer nuclear layer and neurosensory retina thickness measurements and photoreceptor counting were performed. Caspase-1 and caspase-3 were assessed by immunohistochemistry. Dihydroethidium was used to evaluate in situ generation of superoxide and thiobarbituric acid reactive substances were measured in retinal homogenates as indicators of lipid peroxidation. The total antioxidant capacity and oxidative ratio were also determined. Retinas from rabbits exposed to light showed higher levels of lipid peroxidation than the unexposed animals and a decrease in outer nuclear layer and neurosensory retina thickness. Our study demonstrates that light damage produces an increase in retinal oxidative stress immediately after light exposure that decreases one week after exposure. However, some morphological alterations appear days after light exposure including apoptotic phenomena. This model may be useful in the future to study the protective effect of antioxidant substances or new intraocular lenses with yellow filters.