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

Optimization of accelerated solvent extraction of zeaxanthin from orange paprika using response surface methodology and an artificial neural network coupled with a genetic algorithm

This study aimed to optimize the accelerated solvent extraction (ASE) condition of zeaxanthin from orange paprika using a response surface methodology (RSM) or an artificial neural network (ANN) with a genetic algorithm (GA). Input variables were ethanol concentration, extraction time, and extraction temperature, while output variable was zeaxanthin. The mean squared error and regression correlation coefficient of the developed ANN model were 0.3038 and 0.9983, respectively. Predicted optimal extraction conditions from ANN-GA for maximum zeaxanthin were 100% ethanol, 3.4 min, and 99.2 °C. The relative errors under the optimal extraction conditions were RSM for 10.46% and ANN-GA for 2.18%. We showed that the recovery of hydrophobic zeaxanthin could be performed using ethanol, an eco-friendly solvent, via ASE, and the extraction efficiency could be improved by ANN-GA modeling than RSM. Therefore, combining ASE and ANN-GA might be desirable for the efficient and eco-friendly extraction of hydrophobic functional materials from food resources.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01514-8.

Are Hyperglycemia-Induced Changes in the Retina Associated with Diabetes-Correlated Changes in the Brain? A Review from Zebrafish and Rodent Type 2 Diabetes Models

Diabetes is prevalent worldwide, with >90% of the cases identified as Type 2 diabetes. High blood sugar (hyperglycemia) is the hallmark symptom of diabetes, with prolonged and uncontrolled levels contributing to subsequent complications. Animal models have been used to study these complications, which include retinopathy, nephropathy, and peripheral neuropathy. More recent studies have focused on cognitive behaviors due to the increased risk of dementia/cognitive deficits that are reported to occur in older Type 2 diabetic patients. In this review, we collate the data reported from specific animal models (i.e., mouse, rat, zebrafish) that have been examined for changes in both retina/vision (retinopathy) and brain/cognition, including db/db mice, Goto-Kakizaki rats, Zucker Diabetic Fatty rats, high-fat diet-fed rodents and zebrafish, and hyperglycemic zebrafish induced by glucose immersion. These models were selected because rodents are widely recognized as established models for studying diabetic complications, while zebrafish represent a newer model in this field. Our goal is to (1) summarize the published findings relevant to these models, (2) identify similarities in cellular mechanisms underlying the disease progression that occur in both tissues, and (3) address the hypothesis that hyperglycemic-induced changes in retina precede or predict later complications in brain.

NLRP3 Inflammasome Priming in the Retina of Diabetic Mice Requires REDD1-Dependent Activation of GSK3β

Purpose

Inflammasome activation has been implicated in the development of retinal complications caused by diabetes. This study was designed to identify signaling events that promote retinal NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in response to diabetes.

Methods

Diabetes was induced in mice by streptozotocin administration. Retinas were examined after 16 weeks of diabetes. Human MIO-M1 Müller cells were exposed to hyperglycemic culture conditions. Genetic and pharmacological interventions were used to interrogate signaling pathways. Visual function was assessed in mice using a virtual optomotor system.

Results

In the retina of diabetic mice and in Müller cell cultures, NLRP3 and interleukin-1β (IL-1β) were increased in response to hyperglycemic conditions and the stress response protein Regulated in Development and DNA damage 1 (REDD1) was required for the effect. REDD1 deletion prevented caspase-1 activation in Müller cells exposed to hyperglycemic conditions and reduced IL-1β release. REDD1 promoted nuclear factor κB signaling in cells exposed to hyperglycemic conditions, which was necessary for an increase in NLRP3. Expression of a constitutively active GSK3β variant restored NLRP3 expression in REDD1-deficient cells exposed to hyperglycemic conditions. GSK3 activity was necessary for increased NLRP3 expression in the retina of diabetic mice and in cells exposed to hyperglycemic conditions. Müller glia-specific REDD1 deletion prevented increased retinal NLRP3 levels and deficits in contrast sensitivity in diabetic mice.

Conclusions

The data support a role for REDD1-dependent activation of GSK3β in NLRP3 inflammasome transcriptional priming and in the production of IL-1β by Müller glia in response to diabetes.

Lutein/Zeaxanthin Isomers and Quercetagetin Combination Safeguards the Retina from Photo-Oxidative Damage by Modulating Neuroplasticity Markers and the Nrf2 Pathway

Exposure to light-emitting diode (LED) light is a primary cause of retinal damage, resulting in vision loss. Several plant-derived substances, such as lutein and quercetagetin (QCG), show promise in supporting eye health. In this study, the impact of lutein/zeaxanthin (L/Z, Lutemax 2020) and QCG were evaluated individually and together in a rat model of LED-induced retinal damage. A total of 63 Wistar rats were allocated into nine groups (n = 7). For 28 days, the rats received L/Z (10 or 20 mg/kg BW), quercetin (QC, 20 mg/kg BW), QCG (10 or 20 mg/kg BW), or a mixture of different lutein and QCG dosages, after which they were exposed to LED light for 48 h. LED exposure led to a spike in serum malondialdehyde (MDA) and inflammatory cytokines, as well as an increase in retinal NF-κB, ICAM, GFAP, and MCP-1 levels (p < 0.0001 for all). It also reduced serum antioxidant enzyme activities and retinal Nrf2, HO-1, GAP43, NCAM, and outer nuclear layer (ONL) thickness (p < 0.0001 for all). However, administering L/Z and QCG, particularly a 1:1 combination of L/Z and QCG at 20 mg/kg, effectively reversed these changes. The treatment suppressed NF-κB, ICAM, GFAP, and MCP-1 while enhancing Nrf2, HO-1, GAP43, and NCAM and preventing ONL thickness reduction in LED-induced retinal damage rats. In conclusion, while LED light exposure caused retinal damage, treatment with L/Z, QC, and QCG, particularly a combined L/Z and QCG regimen, exhibited protective effects on the retina. This is possibly due to the modulation of neuroplasticity markers and nuclear transcription factors in the rats' retinal cells.

Microvascular changes in obese adults detected by Optical Coherence Tomography Angiography

Aim: The aim of this prospective, controlled, non-randomized study was the comparison of the retinal microvascular parameters of obese and nonobese adults. Methods: 184 eyes of 92 subjects were separated to 3 groups. 68 eyes were in the normal weight group, with a body mass index between 18.5 and 24.5 kg/ m2, 60 eyes were in the overweight group, with a body mass index between 25-29.9 kg/ m2, and 56 eyes were in the obese group, with a body mass index ≥ 30 kg/ m2. All the volunteers were applied visual acuity, ocular motility testing, and slit lamp and mydriatic fundus examination. Optical Coherence Tomography Angiography (OCT-A) scanning was practiced with Optovue (Optovue, Inc; Fremont, CA) on a 6.00 x 6.00 mm macular region, in the central fovea. Results: 184 eyes of ninety-two patients were involved in this prospective study. The vessels' density (VD) in the optic nerve head (ONH) were significantly lower in the overweight and obese adult volunteers compared to the normal weight control group. However, other OCTA parameters (including macular VDs, Foveal avascular zone (FAZ), choriocapillaris plexus (CCP) area) did not demonstrate any significant difference between groups. Subfoveal choroidal thickness (SCT) was higher in the overweight and obese patients when compared to the normal weight control group. Central macular thickness (CMT) did not reveal any significant difference between groups. Conclusion: Even though clinicians are limited in pointing out any differential findings in obese patients only by fundus examination, OCT-A provides a predictable view of the microvascular changes in the retina and choroid in obese patients. Abbreviations: BMI = Body mass index, WHO = World Health Organization, AMD = Age-related macular degeneration, CT = Choroidal thickness, OCTA = Optical Coherence Tomography Angiography, (W/H) ratio = Waist-hip ratio, ETDRS = Early Treatment Diabetic Retinopathy Study, VD = Vessel density, SCP = Superficial capillary plexus, DCP = Deep capillary plexus, CCP = Flow area of the choriocapillaris, FAZ = Avascular zone, CMT = Central macular thickness, ONH = Optic nerve head.

Variations in BCO2 Coding Sequence Causing a Difference in Carotenoid Concentration in the Skin of Chinese Indigenous Chicken

Carotenoid consumption decreases the risk of cancer, osteoporosis, or neurodegenerative diseases through interrupting the formation of free radicals. The deposition of carotenoids in chicken skin makes the skin color turn from white into yellow. The enzyme β-carotene oxygenase 2 (BCO2) plays a key role during the degradation process of carotenoids in skin. How the BCO2 affects the skin color of the chicken and whether it is the key factor that results in the phenotypic difference between yellow- and white-skin chickens are still unclear. In this research, the measurement of the concentration of carotenoids in chicken skin by HPLC showed that the carotenoid concentration in chickens with a yellow skin was significantly higher than that in white-skin chickens. Moreover, there were significant differences in BCO2 gene expression in the back skin between yellow- and white-skin chickens. Scanning the SNPs in BCO2 gene revealed a G/A mutation in exon 6 of the BCO2 gene in white and yellow skin chicken. Generally, one SNP c.890A>G was found to be associated with the chicken skin color and may be used as a genetic marker in breeding for yellow skin in Chinese indigenous chickens.

Remodeling of white adipose tissue microenvironment against obesity by phytochemicals

Obesity is a kind of chronic disease due to a long-term imbalance between energy intake and expenditure. In recent years, the number of obese people around the world has soared, and obesity problem should not be underestimated. Obesity is characterized by changes in the adipose microenvironment, mainly manifested as hypertrophy, chronic inflammatory status, hypoxia, and fibrosis, thus contributing to the pathological changes of other tissues. A plethora of phytochemicals have been found to improve adipose microenvironment, thus prevent and resist obesity, providing a new research direction for the treatment of obesity and related diseases. This paper discusses remodeling of the adipose tissue microenvironment as a therapeutic avenue and reviews the progress of phytochemicals in fighting obesity by improving the adipose microenvironment.

Identification of candidate genes associated with skin yellowness in yellow chickens

The yellow color of the skin is an important economic trait for yellow chickens. Low and non-uniform skin yellowness would reduce economic efficiency. However, the regulatory mechanism of chicken skin yellowness has not been fully elucidated. In this study, we evaluated the skin yellowness of 819 chickens by colorimeter and digital camera, which are from the same batch and the same age of 2 pure lines with significant differences in skin yellowness. A total of 982 candidate differential expressed genes (DEGs) were detected in duodenal tissue by RNA-seq analysis for high and low yellowness chickens. Among the DEGs, we chose fatty acid translocase (CD36) gene and identified a single nucleotide polymorphism (SNP) upstream of the CD36 gene that was significantly associated with skin yellowness at multiple parts of the chicken, and its different genotypes had significant effects on the promoter activity of the CD36 gene. These findings will help to further elucidate the molecular mechanism of chicken skin yellowness and is helpful for improving chicken skin yellowness.

Evaluation of the Anti-Obesity Effect of Zeaxanthin and Exercise in HFD-Induced Obese Rats

Obesity is a worldwide epidemic associated with many health problems. One of the new trends in health care is the emphasis on regular exercise and a healthy diet. Zeaxanthin (Zea) is a carotenoid with many beneficial effects on human health. The aim of this study was to investigate whether the combination of Zea and exercise had therapeutic effects on obesity induced by an HFD in rats. Sixty male Wistar rats were randomly divided into five groups of twelve: rats fed a standard diet; rats fed a high-fat diet (HFD); rats fed an HFD with Zea; rats fed an HFD with Exc; and rats fed an HFD with both Zea and Exc. To induce obesity, rats were fed an HFD for twelve weeks. Then, Zea and exercise were introduced with the HFD for five weeks. The results showed that the HFD significantly increased visceral adipose tissue, oxidative stress, and inflammation biomarkers and reduced insulin, high-density lipoprotein, and antioxidant parameters. Treatments with Zea, Exc, and Zea plus Exc reduced body weight gain, triacylglycerol, glucose, total cholesterol, and nitric oxide levels and significantly increased catalase and insulin compared with the HFD group. This study demonstrated that Zea administration and Exc performance appeared to effectively alleviate the metabolic alterations induced by an HFD. Furthermore, Zea and Exc together had a better effect than either intervention alone.

Stress response protein REDD1 promotes diabetes-induced retinal inflammation by sustaining canonical NF-κB signaling

Inflammation contributes to the progression of retinal pathology caused by diabetes. Here, we investigated a role for the stress response protein regulated in development and DNA damage response 1 (REDD1) in the development of retinal inflammation. Increased REDD1 expression was observed in the retina of mice after 16-weeks of streptozotocin (STZ)-induced diabetes, and REDD1 was essential for diabetes-induced pro-inflammatory cytokine expression. In human retinal MIO-M1 Müller cell cultures, REDD1 deletion prevented increased pro-inflammatory cytokine expression in response to hyperglycemic conditions. REDD1 deletion promoted nuclear factor erythroid-2-related factor 2 (Nrf2) hyperactivation; however, Nrf2 was not required for reduced inflammatory cytokine expression in REDD1-deficient cells. Rather, REDD1 enhanced inflammatory cytokine expression by promoting activation of nuclear transcription factor κB (NF-κB). In WT cells exposed to tumor necrosis factor α (TNFα), inflammatory cytokine expression was increased in coordination with activating transcription factor 4 (ATF4)-dependent REDD1 expression and sustained activation of NF-κB. In both Müller cell cultures exposed to TNFα and in the retina of STZ-diabetic mice, REDD1 deletion promoted inhibitor of κB (IκB) expression and reduced NF-κB DNA-binding activity. We found that REDD1 acted upstream of IκB by enhancing both K63-ubiquitination and auto-phosphorylation of IκB kinase complex. In contrast with STZ-diabetic REDD1^+/+ mice, IκB kinase complex autophosphorylation and macrophage infiltration were not observed in the retina of STZ-diabetic REDD1^-/- mice. The findings provide new insight into how diabetes promotes retinal inflammation and support a model wherein REDD1 sustains activation of canonical NF-κB signaling.

Nanoscale Delivery Systems of Lutein: An Updated Review from a Pharmaceutical Perspective

Carotenoids are natural lipid-soluble pigments that produce yellow to red colors in plants as well as providing bright coloration in vegetables and fruits. Lutein belongs to the xanthophyll subgroup of the carotenoid family, which plays an essential role in photosynthesis and photoprotection in nature. In the human body, lutein, together with its isomer zeaxanthin and its metabolite meso-zeaxanthin, accumulates in the macula of the eye retina, which is responsible for central, high-resolution, and color vision. As a bioactive phytochemical, lutein has essential physiological functions, providing photoprotection against damaging blue light, along with the neutralization of oxidants and the preservation of the structural and functional integrity of cellular membranes. As a potent antioxidant and anti-inflammatory agent, lutein unfortunately has a low bioavailability because of its lipophilicity and a low stability as a result of its conjugated double bonds. In order to enhance lutein stability and bioavailability and achieve its controlled delivery to a target, nanoscale delivery systems, which have great potential for the delivery of bioactive compounds, are starting to be employed. The current review highlights the advantages and innovations associated with incorporating lutein within promising nanoscale delivery systems, such as liposomes, nanoemulsions, polymer nanoparticles, and polymer–lipid hybrid nanoparticles, as well as their unique physiochemical properties.

Therapeutic Potential of Leaves from Fridericia chica (Bonpl.) L. G. Lohmann: Botanical Aspects, Phytochemical and Biological, Anti-Inflammatory, Antioxidant and Healing Action

Plants of the species Fridericia chica (Bonpl.) L. G. Lohmann (Bignoniaceae), which are widely distributed in Brazil and named crajiru in the state of Amazonas, are known in folk medicine as a traditional medicine in the form of a tea for the treatment of intestinal colic, diarrhea, and anemia, among other diseases. The chemical analysis of extracts of the leaves has identified phenolic compounds, a class of secondary metabolites that provide defense for plants and benefits to the health of humans. Several studies have shown the therapeutic efficacy of F. chica extracts, with antitumor, antiviral, wound healing, anti-inflammatory, and antioxidant activities being among the therapeutic applications already proven. The healing action of F. chica leaf extract has been demonstrated in several experimental models, and shows the ability to favor the proliferation of fibroblasts, which is essential for tissue repair. The anti-inflammatory activity of F. chica has been clearly demonstrated by several authors, who suggest that it is related to the presence of 3-deoxyanthocyanidins, which is capable of inhibiting pro-inflammatory pathways such as the kappa B (NF-kB) nuclear transcription factor pathway. Another important effect attributed to this species is the antioxidant effect, attributed to phenolic compounds interrupting chain reactions caused by free radicals and donating hydrogen atoms or electrons. In conclusion, the species Fridericia chica has great therapeutic potential, which is detailed in this paper with the objective of encouraging new research and promoting the sum of efforts for the inclusion of herbal medicines in health systems around the world.

Inflammatory adipose activates a nutritional immunity pathway leading to retinal dysfunction

Age-related macular degeneration (AMD), the leading cause of irreversible blindness among Americans over 50, is characterized by dysfunction and death of retinal pigment epithelial (RPE) cells. The RPE accumulates iron in AMD, and iron overload triggers RPE cell death in vitro and in vivo. However, the mechanism of RPE iron accumulation in AMD is unknown. We show that high-fat-diet-induced obesity, a risk factor for AMD, drives systemic and local inflammatory circuits upregulating interleukin-1β (IL-1β). IL-1β upregulates RPE iron importers and downregulates iron exporters, causing iron accumulation, oxidative stress, and dysfunction. We term this maladaptive, chronic activation of a nutritional immunity pathway the cellular iron sequestration response (CISR). RNA sequencing (RNA-seq) analysis of choroid and retina from human donors revealed that hallmarks of this pathway are present in AMD microglia and macrophages. Together, these data suggest that inflamed adipose tissue, through the CISR, can lead to RPE pathology in AMD.

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.

Effective inhibition of adipogenesis-mediated inflammation by a macular carotenoid, lutein in vitro

An absolute interlinks between inflammation and obesity with scarce investigations on the role of lutein in inflammation-induced obesity motivated us to explore the protective mechanism of lutein on adipogenesis-mediated inflammation in vitro by culturing RAW264.7 macrophages in adipocyte conditioned medium. The RAW264 macrophage cells were cultured with adipocyte-conditioned media, and the potency of lutein on the expression of adipocyte inflammation-associated protein markers (IL-1β, MCP-1, TNF-α, IL-6, NF-κB, and IKKα/β) were analyzed by western blotting. The data revealed that lutein effectively reduces the protein levels of major inflammatory markers such as NF-κB, IL-1β, MCP-1, and TNF-α in differentiated adipocytes. Interestingly, lutein hampered inflammation in the RAW264 cells that were cultured in adipocyte-conditioned media by lowering the protein expression of IL-1β, MCP-1, and TNF-α. The blockage of inflammation by lutein in both differentiated adipocytes, and adipogenesis-induced macrophages is associated with suppression of IKK α/β phosphorylation. These data suggest that lutein potentially alters adipocyte differentiation-mediated inflammation by regulating the NF-κB signaling pathway. Thus, lutein could be utilized as a potent nutraceutical agent in the management of obesity and associated inflammation. PRACTICAL APPLICATIONS: Lutein isolated from a dietary source exhibited an inhibitory effect in adipogenesis-induced inflammations. The findings of this study authenticate the diversified prospective of lutein in regulating obesity and other inflammation-related diseases. Thus, it is understood that continuous intake of lutein-rich food or dietary intervention of lutein may reduce the risk of developing obesity.

The Associations of Plasma Carotenoids and Vitamins With Risk of Age-Related Macular Degeneration: Results From a Matched Case-Control Study in China and Meta-Analysis

Background and Purpose

Data from studies support a beneficial effect of carotenoids and vitamins on an age-related macular degeneration (AMD) risk. However, studies on the relations between blood levels of these nutrients and AMD are limited and provided conflicting results. The objective of this case-control study and meta-analysis was to examine whether the blood concentrations of carotenoids and vitamins were associated with the risk of AMD.

Methods

A total of 164 cases of AMD and an equal number of controls are individually matched according to age and gender among the participants, who provided blood samples in the Xi'an Eye Study. Plasma carotenoids and vitamins were measured using reversed-phase high-performance liquid chromatography. Bonferroni-corrected covariate-adjusted conditional logistic regression were used to estimate AMD risk by category of these nutrients in the multivariable-adjusted model. Nine studies were identified for the meta-analysis and calculated pooled risk estimates by means of a random-effects model.

Results

Plasma concentrations of examined carotenoids and vitamins were significantly lower in patients with AMD than those in controls. Plasma concentrations of examined carotenoids and vitamins were significantly lower in patients with AMD than those in controls. After a multivariate adjustment for body mass index, blood cholesterol, and other lifestyle risk factors, higher lutein/zeaxanthin content in plasma was significantly associated with a decreased risk of AMD, and the odds ratio (OR) comparing the top and bottom tertiles was 0.21 (95% CI: 0.05, 0.84; P_trend = 0.024). Associations for β-carotenes (OR: 0.11; 95% CI: 0.02, 0.50; P_trend < 0.001), and β-cryptoxanthin (OR: 0.08, 95% CI: 0.02, 0.39; P_trend < 0.001) were similar to that for lutein/zeaxanthin. Inverse associations were also observed for a higher level of retinol (OR: 0.14, 95% CI: 0.03, 0.61; P_trend = 0.006) and α-tocopherol (OR: 0.25, 95% CI: 0.06, 0.98; P_trend = 0.006). In the meta-analysis, a protective effect was detected for AMD among the participants with high blood lutein/zeaxanthin level (OR: 0.53, 95% CI: 0.40, 0.72, P < 0.001), compared to those with low level. Similar inverse associations were seen for β-carotene (OR: 0.48, 95% CI: 0.28, 0.84, P = 0.010), β-cryptoxanthin (OR: 0.48, 95% CI: 0.23, 1, P = 0.049), lycopene (OR: 0.70, 95% CI: 0.54, 0.90, P = 0.006) and α-tocopherol (OR: 0.50, 95% CI: 0.31, 0.81, P = 0.005).

Conclusions

Results of the case-control study were consistent with findings from the meta-analysis, indicating that higher concentrations of carotenoids and vitamins were inversely associated with the AMD risk. Our finding supports the current notion that these nutrients are likely to affect the development of AMD and may help to refine the strategies for the prevention of age-related eye diseases.

Thioredoxin interacting protein, a key molecular switch between oxidative stress and sterile inflammation in cellular response

Tissue and systemic inflammation have been the main culprit behind the cellular response to multiple insults and maintaining homeostasis. Obesity is an independent disease state that has been reported as a common risk factor for multiple metabolic and microvascular diseases including nonalcoholic fatty liver disease (NAFLD), retinopathy, critical limb ischemia, and impaired angiogenesis. Sterile inflammation driven by high-fat diet, increased formation of reactive oxygen species, alteration of intracellular calcium level and associated release of inflammatory mediators, are the main common underlying forces in the pathophysiology of NAFLD, ischemic retinopathy, stroke, and aging brain. This work aims to examine the contribution of the pro-oxidative and pro-inflammatory thioredoxin interacting protein (TXNIP) to the expression and activation of NLRP3-inflammasome resulting in initiation or exacerbation of sterile inflammation in these disease states. Finally, the potential for TXNIP as a therapeutic target and whether TXNIP expression can be modulated using natural antioxidants or repurposing other drugs will be discussed.

Short-term high-fat feeding exacerbates degeneration in retinitis pigmentosa by promoting retinal oxidative stress and inflammation

A high-fat diet (HFD) can induce hyperglycemia and metabolic syndromes that, in turn, can trigger visual impairment. To evaluate the acute effects of HFD feeding on retinal degeneration, we assessed retinal function and morphology, inflammatory state, oxidative stress, and gut microbiome in dystrophic retinal degeneration 10 (rd10) mice, a model of retinitis pigmentosa, fed an HFD for 2 to 3 wk. Short-term HFD feeding impaired retinal responsiveness and visual acuity and enhanced photoreceptor degeneration, microglial cell activation, and Müller cell gliosis. HFD consumption also triggered the expression of inflammatory and oxidative markers in rd10 retinas. Finally, an HFD caused gut microbiome dysbiosis, increasing the abundance of potentially proinflammatory bacteria. Thus, HFD feeding drives the pathological processes of retinal degeneration by promoting oxidative stress and activating inflammatory-related pathways. Our findings suggest that consumption of an HFD could accelerate the progression of the disease in patients with retinal degenerative disorders.

Anti-Inflammatory and Anticancer Effects of Microalgal Carotenoids

Acute inflammation is a key component of the immune system's response to pathogens, toxic agents, or tissue injury, involving the stimulation of defense mechanisms aimed to removing pathogenic factors and restoring tissue homeostasis. However, uncontrolled acute inflammatory response may lead to chronic inflammation, which is involved in the development of many diseases, including cancer. Nowadays, the need to find new potential therapeutic compounds has raised the worldwide scientific interest to study the marine environment. Specifically, microalgae are considered rich sources of bioactive molecules, such as carotenoids, which are natural isoprenoid pigments with important beneficial effects for health due to their biological activities. Carotenoids are essential nutrients for mammals, but they are unable to synthesize them; instead, a dietary intake of these compounds is required. Carotenoids are classified as carotenes (hydrocarbon carotenoids), such as α- and β-carotene, and xanthophylls (oxygenate derivatives) including zeaxanthin, astaxanthin, fucoxanthin, lutein, α- and β-cryptoxanthin, and canthaxanthin. This review summarizes the present up-to-date knowledge of the anti-inflammatory and anticancer activities of microalgal carotenoids both in vitro and in vivo, as well as the latest status of human studies for their potential use in prevention and treatment of inflammatory diseases and cancer.

Lutein as a Modulator of Oxidative Stress-Mediated Inflammatory Diseases

Lutein is a xanthophyll carotenoid obtained from various foods, such as dark green leafy vegetables and egg yolk. Lutein has antioxidant activity and scavenges reactive oxygen species such as singlet oxygen and lipid peroxy radicals. Oxidative stress activates inflammatory mediators, leading to the development of metabolic and inflammatory diseases. Thus, recent basic and clinical studies have investigated the anti-inflammatory effects of lutein based on its antioxidant activity and modulation of oxidant-sensitive inflammatory signaling pathways. Lutein suppresses activation of nuclear factor-kB and signal transducer and activator of transcription 3, and induction of inflammatory cytokines (interleukin-1β, interleukin-6, monocyte chemoattratant protein-1, tumor necrosis factor-α) and inflammatory enzymes (cyclooxygenase-2, inducible nitric oxide synthase). It also maintains the content of endogenous antioxidant (glutathione) and activates nuclear factor erythroid 2–related factor 2 (Nrf2) and Nrf2 signaling-related antioxidant enzymes (hemeoxygenase-1, NAD(P)H: quinone oxidoreductase 1, glutathione-s-transferase, glutathione peroxidase, superoxide dismutase, catalase). In this review, we have discussed the current knowledge regarding the anti-inflammatory function of lutein against inflammatory diseases in various organs, including neurodegenerative disorders, eye diseases, diabetic retinopathy, osteoporosis, cardiovascular diseases, skin diseases, liver injury, obesity, and colon diseases.

Therapeutic effect of Keap1-Nrf2-ARE pathway-related drugs on age-related eye diseases through anti-oxidative stress

Age-related eye diseases, including cataract, glaucoma, diabetic retinopathy (DR), and age-related macular degeneration (AMD), are the leading causes of vision loss in the world. Several studies have shown that the occurrence and development of these diseases have an important relationship with oxidative stress in the eye. The Keap1-Nrf2-ARE pathway is a classical pathway that resists oxidative stress and inflammation in the body. This pathway is also active in the development of age-related eye diseases. A variety of drugs have been shown to treat age-related eye diseases through the Keap1-Nrf2-ARE (Kelch-like ECH-Associating protein 1- nuclear factor erythroid 2 related factor 2-antioxidant response element) pathway. This review describes the role of oxidative stress in the development of age-related eye diseases, the function and regulation of the Keap1-Nrf2-ARE pathway, and the therapeutic effects of drugs associated with this pathway on age-related eye diseases.

Effect of a TSPO ligand on retinal pigment epithelial cholesterol homeostasis in high-fat fed mice, implication for age-related macular degeneration

Age-related Macular Degeneration (AMD) is a major cause of sight impairment in the elderly with complex aetiology involving genetics and environment and with limited therapeutic options which have limited efficacy. We have previously shown in a mouse-model of the condition, induced by feeding a high fat diet, that adverse effects of the diet can be reversed by co-administration of the TSPO activator, etifoxine. We extend those observations showing improvements in retinal pigment epithelial (RPE) cells with decreased lipids and enhanced expression of cholesterol metabolism and transport enzymes. Further, etifoxine decreased levels of reactive oxygen species (ROS) in RPE and inflammatory cytokines in RPE and serum. With respect to gut microbiome, we found that organisms abundant in the high fat condition (e.g. in the genus Anaerotruncus and Oscillospira) and implicated in AMD, were much less abundant after etifoxine treatment. The changes in gut flora were associated with the predicted production of metabolites of benefit to the retina including tryptophan and other amino acids and taurine, an essential component of the retina necessary to counteract ROS. These novel observations strengthen earlier conclusions that the mechanisms behind improvements in etifoxine-induced retinal physiology involve an interaction between effects on the host and the gut microbiome.

Deletion of Mitochondrial Translocator Protein (TSPO) Gene Decreases Oxidative Retinal Pigment Epithelial Cell Death via Modulation of TRPM2 Channel

Simple Summary

18 kDa mitochondrial translocator protein (TSPO) is a mitochondria protein of the cellular outer membrane in the mitochondria of several cells, including ARPE19 is TSPO. Accumulating evince indicates that the presence of TSPO participated the modulations of Ca²⁺ homeostasis and mitochondrial free reactive oxygen species (fROS) generation. The deletion of TSPO gene provides to study the action of TSPO on the levels of apoptosis, ADP-ribose (ADPR), mitochondria-fROS (Mito-fROS), and apoptosis via the stimulation of Ca²⁺ permeable channels in the models of cell culture. The stimulations of oxidative stress and ADPR induce the activation of TRPM2 in the ARPE19. For clarifying the involvement of TSPO in retinal human diseases, we used the ARPE19 human cell culture model. The current results demonstrated that the deletion of TSPO induces the regulation of TRPM2 in the TSPO gene knockout ARPE19 (ARPE19-KO) In fact, the present results show that the presence of TSPO increased the upregulations of apoptosis and mitochondria oxidative cytotoxicity values via stimulation of TRPM2 in the ARPE19. Nevertheless, the blockages of PARP-1 (PJ34 and DPQ) and TRPM2 (2APB and ACA) downregulated the values of cell death and oxidative cytotoxicity in the ARPE19. In summary, present results clearly demonstrate that the deletion of TSPO decreases mitochondrial oxidative cytotoxicity-mediated cell death via the modulation of TRPM2 in the ARPE19.

Abstract

The current results indicated the possible protective actions of 18 kDa mitochondrial translocator protein (TSPO) deletion on TRPM2 stimulation, mitochondrial free ROS (Mito-fROS) and apoptotic harmful actions in the cells of adult retinal pigment epithelial19 (ARPE19). There was a direct relationship between TSPO and the disease of age-related macular degeneration. The nature of TSPO implicates upregulation of Mito-fROS and apoptosis via the activation of Ca²⁺ channels in ARPE19, although deletion of TSPO gene downregulates the activation. The decrease of oxidative cytotoxicity and apoptosis might induce in TSPO gene deleted cells by the inhibition of Mito-fROS and PARP-1 activation-induced TRPM2 cation channel activation. The ARPE19 cells were divided into two main groups as TSPO expressing (ARPE19) and non-expressing cells (ARPE19-KO). The levels of caspase -3 (Casp -3), caspase -9 (Casp -9), apoptosis, Mito-fROS, TRPM2 current and intracellular free Ca²⁺ were upregulated in the ARPE19 by the stimulations of H₂O₂ and ADP-ribose, although their levels were downregulated in the cells by the modulators of PARP-1 (DPQ and PJ34), TRPM2 (ACA and 2APB) and glutathione. However, the H₂O₂ and ADP-ribose-mediated increases were not observed in the ARPE19-KO. The expression levels of Bax, Casp -3, Casp -9 and PARP-1 were higher in the ARPE19 group as compared to the ARPE19-KO group. In summary, current results confirmed that TRPM2-mediated cell death and oxidative cytotoxicity in the ARPE19 cells were occurred by the presence of TSPO. The deletion of TSPO may be considered as a therapeutic way to TRPM2 activation-mediated retinal oxidative injury.

Wolfberry (Lycium barbarum) Consumption with a Healthy Dietary Pattern Lowers Oxidative Stress in Middle-Aged and Older Adults: A Randomized Controlled Trial

Incorporating zeaxanthin-rich wolfberry (Lycium barbarum) into a healthy dietary pattern may augment its antioxidant potential. The present 16-week, parallel design randomized controlled trial aimed to investigate the impact of adhering to a healthy dietary pattern, either with or without whole dried wolfberry (15 g/d) on oxidative stress status (plasma malondialdehyde and 8-iso-prostaglandin F2α) in middle-aged and older adults. Changes to carotenoids status (plasma and skin carotenoids) and body composition were further evaluated to explore potential mechanisms which underlie the antioxidant properties of wolfberry. Plasma 8-iso-prostaglandin F2α, plasma zeaxanthin and skin carotenoids status were significantly raised in the wolfberry consuming group (n = 22; p < 0.05) compared to the control group which showed no changes (n = 18). Likewise in the wolfberry group only, inverse association was observed between the change values of plasma zeaxanthin and plasma 8-iso-prostaglandin F2α (−0.21 (−0.43, 0.00) ng/µmol, regression coefficient (95% CI); p = 0.05). Wolfberry consumption with a healthy dietary pattern may serve as a dietary strategy to attenuate lipid peroxidation among middle-aged and older adults who are at a heightened risk of oxidative stress induced age-related disorders. The antioxidant properties of wolfberry may be attributed to its rich zeaxanthin content.

Light Environment Influences Developmental Programming of the Metabolic and Visual Systems in Mice

Purpose

Light is a salient cue that can influence neurodevelopment and the immune system. Light exposure out of sync with the endogenous clock causes circadian disruption and chronic disease. Environmental light exposure may contribute to developmental programming of metabolic and neurological systems but has been largely overlooked in Developmental Origins of Health and Disease (DOHaD) research. Here, we investigated whether developmental light exposure altered programming of visual and metabolic systems.

Methods

Pregnant mice and pups were exposed to control light (12:12 light:dark) or weekly light cycle inversions (circadian disruption [CD]) until weaning, after which male and female offspring were housed in control light and longitudinally measured to evaluate differences in growth (weight), glucose tolerance, visual function (optomotor response), and retinal function (electroretinogram), with and without high fat diet (HFD) challenge. Retinal microglia and macrophages were quantified by positive Iba1 and CD11b immunofluorescence.

Results

CD exposure caused impaired visual function and increased retinal immune cell expression in adult offspring. When challenged with HFD, CD offspring also exhibited altered retinal function and sex-specific impairments in glucose tolerance.

Conclusions

Overall, these findings suggest that the light environment contributes to developmental programming of the metabolic and visual systems, potentially promoting a pro-inflammatory milieu in the retina and increasing the risk of visual disease later in life.

A novel gastroprotective effect of zeaxanthin against stress-induced gastritis in male rats targeting the expression of HIF-1α, TFF-1 and MMP-9 through PI3K/Akt/JNK signaling pathway

Stress-induced gastritis is a common problem in the intensive care unit. Zeaxanthin (ZE), a non-provitamin A carotenoid has been known to exert antioxidant and anti-inflammatory effects. In this study, we examined the effect of ZE on water avoidance stress (WAS)-induced gastritis in rats. 24 Sprague' Dawley male rats were divided into four groups; control, ZE, WAS and WAS+ZE. In the stressed rats, treatment with ZE effectively downregulated the gastric levels of total oxidant status (TOS), myeloperoxidase (MPO) and malondialdehyde (MDA), with significant upregulation of the antioxidant enzymes' activities and gastric levels of prostagladin-E2 (PGE2) as compared to the untreated stressed one. As noticed in the present study, ZE significantly decrease the gastric levels of interleukin-1 β (IL-1β) and IL-6 as well as suppression of nuclear transcription factor kappa-B (NF-κB) immunohistochemical expression together with upregulation of trefoil factor-1 (TFF-1) gene expression. Moreover, in the untreated WAS-induced gastritis group, gastrin and corticosterone levels were significantly increased together with upregulation of the gene expression of hypoxia inducible factor-1α (HIF-1α), matrix metalloproteinase-9 (MMP-9), PI3K, Akt and JNK in the gastric tissues, which significantly improved by ZE administration. These all positive effects of ZE reflected on reduction of microscopic gastric mucosal damage and inflammatory cell infiltration with improvement of ulcer score. Our results discover that ZE has a new gastroprotective effect against stress-induced gastritis in rats, primarily through its antioxidative and anti-inflammatory effects, which are expressed in the regulation of the MMP-9 and HIF-1α signaling pathways.

Impacts of high fat diet on ocular outcomes in rodent models of visual disease

High fat diets (HFD) have been utilized in rodent models of visual disease for over 50 years to model the effects of lipids, metabolic dysfunction, and diet-induced obesity on vision and ocular health. HFD treatment can recapitulate the pathologies of some of the leading causes of blindness, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) in rodent models of visual disease. However, there are many important factors to consider when using and interpreting these models. To synthesize our current understanding of the importance of lipid signaling, metabolism, and inflammation in HFD-driven visual disease processes, we systematically review the use of HFD in mouse and rat models of visual disease. The resulting literature is grouped into three clusters: models that solely focus on HFD treatment, models of diabetes that utilize both HFD and streptozotocin (STZ), and models of AMD that utilize both HFD and genetic models and/or other exposures. Our findings show that HFD profoundly affects vision, retinal function, many different ocular tissues, and multiple cell types through a variety of mechanisms. We delineate how HFD affects the cornea, lens, uvea, vitreous humor, retina, retinal pigmented epithelium (RPE), and Bruch's membrane (BM). Furthermore, we highlight how HFD impairs several retinal cell types, including glia (microglia), retinal ganglion cells, bipolar cells, photoreceptors, and vascular support cells (endothelial cells and pericytes). However, there are a number of gaps, limitations, and biases in the current literature. We highlight these gaps and discuss experimental design to help guide future studies. Very little is known about how HFD impacts the lens, ciliary bodies, and specific neuronal populations, such as rods, cones, bipolar cells, amacrine cells, and retinal ganglion cells. Additionally, sex bias is an important limitation in the current literature, with few HFD studies utilizing female rodents. Future studies should use ingredient-matched control diets (IMCD), include both sexes in experiments to evaluate sex-specific outcomes, conduct longitudinal metabolic and visual measurements, and capture acute outcomes. In conclusion, HFD is a systemic exposure with profound systemic effects, and rodent models are invaluable in understanding the impacts on visual and ocular disease.

The effect of lutein and Urtica dioica extract on in vitro production of embryo and oxidative status in polycystic ovary syndrome in a model of mice

BACKGROUND

Polycystic ovary syndrome (PCOS) is one of the most prevalent endocrinopathies in women during the reproductive age. Herbal medicines are used increasingly alone or in supplement with chemical medicines for the treatment of different diseases and dysfunctions. This study was aimed to evaluate the effects of lutein and nettle (Urtica dioica) extract on the biochemical parameters and the reproductive function in the PCOS model of mice.

METHODS

Following the induction of PCOS by dehydroepiandrosterone (DHEA), the mice (n = 98) were randomly assigned into seven groups, each consisting of fourteen mice; the groups were included control group (received solvent), PCOS group (received 6 mg/100 g B.W/day IP, DHEA for 21 days), PCOS+ Nettle extract (200 and 400 mg/kg), PCOS+ Lutein (125 and 250 mg/kg), and PCOS+ NL (200 mg/kg nettle extract and 125 mg/kg lutein). The nettle extract and lutein were administrated using gavage for 30 consecutive days after PCOS induction. Malondialdehyde (MDA), total antioxidant capacity (TAC), and estrogen were measured in serum, ovary, and uterus samples by the ELISA method. The total number of oocytes, oocyte quality, fertilization rate, 2-cell blastocyst, and arrested embryos (type I, type II, and type III) were also investigated.

RESULTS

A combination treatment of the nettle and lutein produced the lowest concentration of MDA in comparison to other groups which affected by the PCOS. The lowest level of TAC was observed in the PCOS group without treatment. The number of oocytes, oocyte quality, fertilization rate, and 2-cell blastocyst were significantly higher in the control group, but the lowest values were observed in the PCOS group without any treatment.

CONCLUSIONS

The most favorable findings include improving antioxidant capacity, oocyte and embryo quality were observed in the PCOS+ 125 L group.

Effects of Resvega on Inflammasome Activation in Conjunction with Dysfunctional Intracellular Clearance in Retinal Pigment Epithelial (RPE) Cells

Age-related macular degeneration (AMD) is an eye disease in which retinal pigment epithelium (RPE) cells play a crucial role in maintaining retinal homeostasis and photoreceptors’ functionality. During disease progression, there is increased inflammation with nucleotide-binding domain, leucine-rich repeat, and Pyrin domain 3 (NLRP3) inflammasome activation, oxidative stress, and impaired autophagy in RPE cells. Previously, we have shown that the dietary supplement Resvega reduces reactive oxygen species (ROS) production and induces autophagy in RPE cells. Here, we investigated the ability of Resvega to prevent NLRP3 inflammasome activation with impaired protein clearance in human RPE cells. Cell viability was measured using the lactate dehydrogenase (LDH) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Enzyme-linked immunosorbent assays (ELISA) were utilized to determine the secretion of cytokines, NLRP3, and vascular endothelial growth factor (VEGF). Caspase-1 activity was measured with a fluorescent labeled inhibitor of caspase-1 (FLICA; FAM-YVAD-FMK) and detected microscopically. Resvega improved the cell membrane integrity, which was evident as reduced LDH leakage from cells. In addition, the caspase-1 activity and NLRP3 release were reduced, as was the secretion of two inflammatory cytokines, interleukin (IL)-1β and IL-8, in IL-1α-primed ARPE-19 cells. According to our results, Resvega can potentially reduce NLRP3 inflammasome-mediated inflammation in RPE cells with impaired protein clearance.

Beyond AREDS Formulations, What Is Next for Intermediate Age-Related Macular Degeneration (iAMD) Treatment? Potential Benefits of Antioxidant and Anti-inflammatory Apocarotenoids as Neuroprotectors

Age-related macular degeneration (AMD) is the commonest cause of severe visual loss and blindness in developed countries among individuals aged 60 and older. AMD slowly progresses from early AMD to intermediate AMD (iAMD) and ultimately late-stage AMD. Late AMD encompasses either neovascular AMD (nAMD) or geographic atrophy (GA). nAMD is defined by choroidal neovascularization (CNV) and hemorrhage in the subretinal space at the level of the macula. This induces a rapid visual impairment caused by the death of photoreceptor cells. Intravitreal injection of anti-vascular endothelial growth factor (VEGF) antibodies is the standard treatment of nAMD but adds to the burden of patient care. GA is characterized by slowly expanding photoreceptor, and retinal pigment epithelium (RPE) degeneration patches progressively leading to blindness. There is currently no therapy to cure GA. Late AMD continues to be an unmet medical need representing a major health problem with millions of patients worldwide. Oxidative stress and inflammation are recognized as some of the main risk factors to developing late AMD. The antioxidant formulation AREDS (Age-Related Eye Disease Studies), contains β-carotene, which has been replaced by lutein and zeaxanthin in AREDS2, are given to patients with iAMD but have a limited effect on the incidence of nAMD and GA. Thus, to avoid or slowdown the development of late stages of AMD (nAMD or GA), new therapies targeting iAMD are needed such as crocetin obtained through hydrolysis of crocin, an important component of saffron (Crocus sativus L.), and norbixin derived from bixin extracted from Bixa orellana seeds. We have shown that these apocarotenoids preserved more effectively RPE cells against apoptosis following blue light exposure in the presence of A2E than lutein and zeaxanthin. In this review, we will discuss the potential use of apocarotenoids to slowdown the progression of iAMD, to reduce the incidence of both forms of late AMD.

Chili Pepper Carotenoids: Nutraceutical Properties and Mechanisms of Action

Chili pepper is a prominent cultivated horticultural crop that is traditionally used for food seasoning and is applied for the treatment and prevention of multiple diseases. Its beneficial health properties are due to its abundance and variety of bioactive components, such as carotenoids, capsaicinoids, and vitamins. In particular, carotenoids have important nutraceutical properties, and several studies have focused on their potential in the prevention and treatment of human diseases. In this article, we reviewed the state of knowledge of general aspects of chili pepper carotenoids (biosynthesis pathway, types and content in Capsicum spp., and the effects of processing on carotenoid content) and recent findings on the effects of carotenoid nutraceuticals, such as antioxidant, cancer preventive, anti-inflammatory, cardiovascular disorder preventive, and anti-obesity effects.

Oxidative Stress and Marine Carotenoids: Application by Using Nanoformulations

Carotenoids are natural fat-soluble pigments synthesized by plants, algae, fungi and microorganisms. They are responsible for the coloration of different photosynthetic organisms. Although they play a role in photosynthesis, they are also present in non-photosynthetic plant tissues, fungi, and bacteria. These metabolites have mainly been used in food, cosmetics, and the pharmaceutical industry. In addition to their utilization as pigmentation, they have significant therapeutically applications, such as improving immune system and preventing neurodegenerative diseases. Primarily, they have attracted attention due to their antioxidant activity. Several statistical investigations indicated an association between the use of carotenoids in diets and a decreased incidence of cancer types, suggesting the antioxidant properties of these compounds as an important factor in the scope of the studies against oxidative stress. Unusual marine environments are associated with a great chemical diversity, resulting in novel bioactive molecules. Thus, marine organisms may represent an important source of novel biologically active substances for the development of therapeutics. Marine carotenoids (astaxanthin, fucoxanthin, β-carotene, lutein but also the rare siphonaxanthin, sioxanthin, and myxol) have recently shown antioxidant properties in reducing oxidative stress markers. Numerous of bioactive compounds such as marine carotenoids have low stability, are poorly absorbed, and own very limited bioavailability. The new technique is nanoencapsulation, which can be used to preserve marine carotenoids and their original properties during processing, storage, improve their physiochemical properties and increase their health-promoting effects. This review aims to describe the role of marine carotenoids, their potential applications and different types of advanced nanoformulations preventing and treating oxidative stress related disorders.

Deletion of Thioredoxin-Interacting Protein (TXNIP) Abrogates High Fat Diet-induced Retinal Leukostasis, Barrier Dysfunction and Microvascular Degeneration in a Mouse Obesity Model

We have shown that a high fat diet (HFD) induces the activation of retinal NOD-like receptor protein (NLRP3)-inflammasome that is associated with enhanced expression and interaction with thioredoxin-interacting protein (TXNIP). Here, the specific contribution of TXNIP and the impact of HFD on retinal leukostasis, barrier dysfunction and microvascular degeneration were investigated. Wild-type (WT) and TXNIP knockout (TKO) mice were fed with normal diet or 60% HFD for 8–18 weeks. TXNIP was overexpressed or silenced in human retinal endothelial cells (REC). At 8 weeks, HFD significantly induced retinal leukostasis and breakdown of the blood–retina barrier in WT mice, but not in TKO mice. In parallel, HFD also induced retinal expression of adhesion molecules and cleaved IL-1β in WT mice, which were also abrogated in TKO mice. In culture, TXNIP overexpression induced NLRP3, IL-1β, and adhesion molecules expression, while TXNIP silencing inhibited them. Blocking the IL-1β receptor significantly suppressed TXNIP-induced expression of NLRP3-inflammasome and adhesion molecules in HREC. Ex-vivo assay showed that leukocytes isolated from WT-HFD, but not from TKO-HFD, induced leukostasis and cell death. At 18 weeks, HFD triggered development of degenerated (acellular) capillaries and decreased branching density in WT but not in TKO mice. Together, HFD-induced obesity triggered early retinal leukostasis and microvascular dysfunction at least in part via TXNIP-NLRP3-inflammasome activation.

Effects of lutein supplementation in age-related macular degeneration

The purpose of this meta-analysis was to evaluate the effects of lutein supplementation on macular pigment optical density (MPOD) in randomized controlled trials involving patients with age-related macular degeneration (AMD). A comprehensive search of the literature was performed in PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese Biomedical Literature Database, and Wan Fang database through December 2018. Nine randomized controlled trials involving 920 eyes (855 with AMD) were included. Meta-analysis suggested that lutein supplementation (10 or 20 mg per day) was associated with an increase in MPOD (mean difference (MD) 0.07; 95% confidence interval (CI) 0.03 to 0.10), visual acuity (MD 0.28; 95%CI 0.06 to 0.50) and contrast sensitivity (MD 0.26; 95%CI 0.22 to 0.30). Stratified analyses showed the increase in MPOD to be faster and greater with higher dose and longer treatment. The available evidence suggests that dietary lutein may be beneficial to AMD patients and the higher dose could make MPOD increase in a shorter time.

Relationships Between Neurodegeneration and Vascular Damage in Diabetic Retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes and constitutes a major cause of vision impairment and blindness in the world. DR has long been described exclusively as a microvascular disease of the eye. However, in recent years, a growing interest has been focused on the contribution of neuroretinal degeneration to the pathogenesis of the disease, and there are observations suggesting that neuronal death in the early phases of DR may favor the development of microvascular abnormalities, followed by the full manifestation of the disease. However, the mediators that are involved in the crosslink between neurodegeneration and vascular changes have not yet been identified. According to our hypothesis, vascular endothelial growth factor (VEGF) could probably be the most important connecting link between the death of retinal neurons and the occurrence of microvascular lesions. Indeed, VEGF is known to play important neuroprotective actions; therefore, in the early phases of DR, it may be released in response to neuronal suffering, and it would act as a double-edged weapon inducing both neuroprotective and vasoactive effects. If this hypothesis is correct, then any retinal stress causing neuronal damage should be accompanied by VEGF upregulation and by vascular changes. Similarly, any compound with neuroprotective properties should also induce VEGF downregulation and amelioration of the vascular lesions. In this review, we searched for a correlation between neurodegeneration and vasculopathy in animal models of retinal diseases, examining the effects of different neuroprotective substances, ranging from nutraceuticals to antioxidants to neuropeptides and others and showing that reducing neuronal suffering also prevents overexpression of VEGF and vascular complications. Taken together, the reviewed evidence highlights the crucial role played by mediators such as VEGF in the relationship between retinal neuronal damage and vascular alterations and suggests that the use of neuroprotective substances could be an efficient strategy to prevent the onset or to retard the development of DR.

Mechanistic insights into the effect of lutein on atherosclerosis, vascular dysfunction, and related risk factors: A systematic review of in vivo, ex vivo and in vitro studies

Lutein is an essential carotenoid commonly consumed in the diet; however, its dietary intake does not usually reach the minimum recommended intake to decrease the incidence of chronic diseases. Experimental and epidemiological evidence suggests an anti-atherosclerotic effect for lutein-rich foods or lutein supplementation. This systematic review aimed to assess the mechanistic pathways of lutein in the prevention of atherosclerosis. Electronic databases, including PubMed, SCOPUS, ProQuest, Embase, and Google Scholar were searched to May 2019. Original studies published in English-language journals that investigated the effects of lutein on atherosclerosis and related risk factors, including lipid profile, hemodynamic, glycemic and inflammatory measurements, and endothelial function indices, were considered. Two reviewers independently extracted data on study characteristics, methods and outcomes. The review protocol has been registered at PROSPERO database of Systematic Reviews (registration number: CRD42019121381). A total of 5818 articles were found in the first phase of the search; from these, 19 met the inclusion criteria: 3 in vitro, 1 ex vivo, 11 animal, and 4 human studies. Nine of ten studies showed positive effects of lutein on endothelial function by reducing blood pressure, arterial thickness, monocyte migration, and vascular smooth muscle cell migration. Twelve studies examined the anti-inflammatory properties of lutein and found a significant decrease in proinflammatory cytokines. Although few studies investigated the anti-hyperlipidemic effects of lutein, three animal studies and one clinical trial found a beneficial effect of lutein on lipid profile. Evidence supports positive effects of lutein on atherosclerosis development and some common risk factors of atherosclerosis, including inflammation and endothelial dysfunction. Further studies focused on the effects of lutein on hyperglycemia, lipid profile, blood pressure and coagulation are required.

Zeaxanthin: Metabolism, Properties, and Antioxidant Protection of Eyes, Heart, Liver, and Skin

Zeaxanthin, a non-provitamin A carotenoid that belongs to the xanthophyll family, has been less studied than its isomer lutein. However, zeaxanthin has also been shown to have a number of beneficial effects for human health due to its ability to quench free radicals, exert antioxidant effects, as well as decrease inflammation. It is the purpose of this review to discuss the metabolism of zeaxanthin, including digestion, absorption, transport, and uptake by tissues, as well as the dietary or other factors which affect zeaxanthin bioavailability. In addition, this review also focuses on specific effects of this carotenoid on eye, skin, liver, and cardiovascular health. Data derived from human interventions, animal models of research, and in vitro and cell studies are discussed in this review.

HO-1 overexpression and underexpression: Clinical implications

In this review we examine the effects of both over- and under-production of heme oxygenase-1 (HO-1) and HO activity on a broad spectrum of biological systems and on vascular disease. In a few instances e.g., neonatal jaundice, overproduction of HO-1 and increased HO activity results in elevated levels of bilirubin requiring clinical intervention with inhibitors of HO activity. In contrast HO-1 levels and HO activity are low in obesity and the HO system responds to mitigate the deleterious effects of oxidative stress through increased levels of bilirubin (anti-inflammatory) and CO (anti-apoptotic) and decreased levels of heme (pro-oxidant). Site specific HO-1 overexpression diminishes adipocyte terminal differentiation and lipid accumulation of obesity mediated release of inflammatory molecules. A series of diverse strategies have been implemented that focus on increasing HO-1 and HO activity that are central to reversing the clinical complications associated with diseases including, obesity, metabolic syndrome and vascular disease.

Bamboo Leaf Flavonoids Extracts Alleviate Oxidative Stress in HepG2 Cells via Naturally Modulating Reactive Oxygen Species Production and Nrf2-Mediated Antioxidant Defense Responses

In this study, bamboo leaf flavonoids extracts (BFE) were employed to alleviate oxidative stress induced by oleic acid in HepG2 cells. Biochemical indexes, intracellular reactive oxygen species production, lipid droplets accumulation, antioxidant enzymes production, and mitochondrial membrane potential were determined to show the alleviation performance of BFE intervention (P < 0.05). Importantly, the results of qRT-PCR and western blot determination indicated that BFE intervention upregulated the expression of Nrf2/HO-1/NQO1 to initiate the antioxidant defense response for counteracting oxidative stress (P < 0.05). Moreover, mitochondrial membrane potential-mediated apoptosis and FOXO signaling pathway initiation caused by BFE intervention may together contribute to oxidative stress alleviation in HepG2 cells. In conclusion, these findings suggested that BFE intervention upregulated related antioxidant defense responses for preventing cells from oxidative damage. PRACTICAL APPLICATION: In this study, bamboo leaf flavonoids extracts intervention upregulated related antioxidant defense responses for preventing cells from oxidative damage. These findings in bamboo leaf extracts antioxidants are a promising and innovative subject with practical applications to enhance the development of bamboo leaf extracts functional products in the food industry.

Carotenoids: How Effective Are They to Prevent Age-Related Diseases?

Despite an increase in life expectancy that indicates positive human development, a new challenge is arising. Aging is positively associated with biological and cognitive degeneration, for instance cognitive decline, psychological impairment, and physical frailty. The elderly population is prone to oxidative stress due to the inefficiency of their endogenous antioxidant systems. As many studies showed an inverse relationship between carotenoids and age-related diseases (ARD) by reducing oxidative stress through interrupting the propagation of free radicals, carotenoid has been foreseen as a potential intervention for age-associated pathologies. Therefore, the role of carotenoids that counteract oxidative stress and promote healthy aging is worthy of further discussion. In this review, we discussed the underlying mechanisms of carotenoids involved in the prevention of ARD. Collectively, understanding the role of carotenoids in ARD would provide insights into a potential intervention that may affect the aging process, and subsequently promote healthy longevity.

The protective effect of zeaxanthin on human limbal and conjunctival epithelial cells against UV-induced cell death and oxidative stress

AIM

To explore the protective effect of zeaxanthin on human limbal and conjunctival epithelial cells against UV-radiation and excessive oxidative stress.

METHODS

Human limbal and conjunctival epithelial cells were isolated from cadaver and cultured in vitro. They were challenged with UVB radiation and H₂O₂ with and without zeaxanthin pretreatment. Cell viability, p38 and c-JUN NH(2)-terminal kinase (JNK) phosphorylation, IL-6, IL-8 and MCP-1 secretion and malondialdehyde (MDA) content were measured.

RESULTS

Zeaxanthin had no measurable cytotoxicity on limbal or conjunctival epithelial cells when used at concentrations of 5 µg/mL and below. At 30 mJ/cm² UVB, the pretreatment of zeaxanthin increased the percentage of live cells from 50% to 69% (P=0.01) and from 66% to 75% (P=0.05) for limbal and conjunctival epithelial cells, respectively. The concentrations of IL-6, IL-8 and MCP-1 in the culture medium reduced to 66% (for IL-6 and MCP-1) and 56% (for IL-8) of the levels without zeaxanthin. This was accompanied by reduced p38 and JNK protein phosphorylation. Pretreatment of zeaxanthin also reduced intracellular MDA content caused by H₂O₂ stimulation from 0.86 µmol/L to 0.52 µmol/L (P=0.02) in limbal epithelial cells and from 0.96 µmol/L to 0.56 µmol/L in conjunctival epithelial cells (P=0.03). However, zeaxanthin did not have significant effect on H₂O₂-induced cell death in limbal or conjunctival epithelial cells.

CONCLUSION

Zeaxanthin is an effective reagent in reducing the detrimental effect of UV-radiation and oxidative stress on ocular surface epithelial cells.

Mechanism and Potential of Egg Consumption and Egg Bioactive Components on Type-2 Diabetes

Type-2 diabetes (T2D) is one of the major global health challenges and a substantial economic burden. Egg and egg-derived components have been indicated to possess antioxidant, anti-inflammatory, anti-hypertensive, immunomodulatory, and anti-cancer activities. However, the scientific evidence about the benefits of egg on T2D is debatable. The relationship between egg consumption and the risk of T2D from observational epidemiological studies is not consistent. Interventional clinical studies, however, provide promising evidence that egg consumption ameliorates the risk of T2D. Current research progress also indicates that some egg components and egg-derived peptides might be beneficial in the context of T2D, in terms of insulin secretion and sensitivity, oxidative stress, and inflammation, suggesting possible application on T2D management. The current review summarizes recent clinical investigations related to the influence of egg consumption on T2D risk and in vivo and in vitro studies on the effect and mechanism of egg components and egg-derived peptides on T2D.

(3R, 3'R)-zeaxanthin protects the retina from photo-oxidative damage via modulating the inflammation and visual health molecular markers

PURPOSE

Zeaxanthin protects the macula from ocular damage due to light or radiation by scavenging harmful reactive oxygen species. In the present study, zeaxanthin product (OmniXan®; OMX), derived from paprika pods (Capsicum annum; Family-Solanaceae), was tested for its efficacy in the rat retina against photooxidation.

METHODS

Forty-two male 8-week-old Wistar rats exposed to 12L/12D, 16L/8D and 24L/0D hours of intense light conditions were orally administrated either 0 or 100 mg/kg BW of zeaxanthin concentration. Retinal morphology was analyzed by histopathology, and target gene expressions were detected with real-time polymerase chain reaction methods.

RESULTS

OMX treatment significantly increased the serum zeaxanthin concentration (p < 0.001) and ameliorated oxidative damage by increasing the antioxidant enzyme activities in the retina induced by light (p < 0.001). OMX administration significantly upregulated the expression of genes, including Rhodopsin (Rho), Rod arrestin (SAG), Gα Transducin 1 (GNAT-1), neural cell adhesion molecule (NCAM), growth-associated protein 43 (GAP43), nuclear factor-(erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase (HO-1) and decreased the expression of nuclear factor-κB (NF- κB) and GFAP by OMX treatment rats. The histologic findings confirmed the antioxidant and gene expression data.

CONCLUSIONS

This study suggests that OMX is a potent substance that can be used to protect photoreceptor cell degeneration in the retina exposed to intense light.

The effects of lutein on optic nerve injury induced by ethambutol and isoniazid: an experimental study

AIM

Ethambutol and isoniazid are two major effective first line agents in tuberculosis treatment having some visual adverse effects. We aimed to determine the protective effects of lutein on oxidative optic neuropathy induced by ethambutol and isoniazid in an experimental model.

MATERIAL AND METHOD

Totally 24 albino Wistar male rats were assigned into 4 groups, with 6 rats in each group as follows: healthy controls (HC group), 50 mg/kg ethambutol +50 mg/kg isoniazid administered group (EI), 0.5 mg/kg lutein +50 mg/kg ethambutol +50 mg/kg isoniazid administered group (LEI-05) and only Lutein (0.5 mg/kg) (LUT group) administered group. From the blood samples and tissues obtained from the rats, Malondialdehyde (MDA), total glutathione (GSH), interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) levels were studied. Histopathological evaluations were performed at the end of the study.

RESULTS

Serum and tissue IL-1β, TNF-α and MDA levels were the highest in EI group which were significantly lower in lutein administered group. On the other hand, serum and tissue total GSH levels were the lowest in EI group which were significantly higher in Lutein administered group. In histopathological evaluations, there were significant differences between EI group and all other three groups with edema and hemorrhage in connective tissue covering optic nerve, dilated and congested capillary, decrease in astrocytes and oligodendrocytes.

CONCLUSION

Isoniazid and ethambutol induced toxic optic neuropathy although not common, may have some potential devastating effects on vision. Lutein is determined as an effective agent in prevention of isoniazid and ethambutol induced toxic optic neuropathy.

Oxidative Stress in Age-Related Macular Degeneration: Nrf2 as Therapeutic Target

Age-related macular degeneration is one of the leading causes of vision loss in the elderly. Genetics, environmental insults, and age-related issues are risk factors for the development of the disease. All these risk factors are linked to the induction of oxidative stress. In young subjects retinal pigment epithelial cells mitigate reactive oxygen generation by the elimination of dysfunctional mitochondria, via mitophagy, and by increasing antioxidant defenses via Nrf2 activation. The high amount of UV light absorbed by the retina, together with cigarette smoking, cooperate with the aging process to increase the amount of reactive oxygen species generated by retinal pigment epithelium where oxidative stress arises. Moreover, in the elderly both the mitophagic process and Nrf2 activation are impaired thus causing retinal cell death. This review will focus on the impact of oxidative stress on the pathogenesis of age-related macular degeneration and analyze the natural and synthetic Nrf2-activating compounds that have been tested as potential therapeutic agents for the disease.

Lipoic Acid and Progesterone Alone or in Combination Ameliorate Retinal Degeneration in an Experimental Model of Hereditary Retinal Degeneration

Retinitis pigmentosa (RP) is a group of inherited retinopathies characterized by photoreceptors death. Our group has shown the positive progesterone (P4) actions on cell death progression in an experimental model of RP. In an effort to enhance the beneficial effects of P4, the aim of this study was to combine P4 treatment with an antioxidant [lipoic acid (LA)] in the rd1 mice. rd1 and control mice were treated with 100 mg/kg body weight of P4, LA, or a combination of both on postnatal day 7 (PN7), 9, and 11, and were sacrificed at PN11. The administration of LA and/or P4 diminishes cell death in rd1 retinas. The effect obtained after the combined administration of LA and P4 is higher than the one obtained with LA or P4 alone. The three treatments decreased GFAP staining, however, in the far peripheral retina, and the two treatments that offered better results were LA and LA plus P4. LA or LA plus P4 increased retinal glutathione (GSH) concentration in the rd1 mice. Although LA and P4 are able to protect photoreceptors from death in rd1 mice retinas, a better effectiveness is achieved when administering LA and P4 at the same time.