Systemic epigallocatechin gallate protects against retinal degeneration and hepatic oxidative stress in the P23H-1 rat

The mechanisms of natural products for eye disorders by targeting mitochondrial dysfunction

The human eye is susceptible to various disorders that affect its structure or function, including glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitochondrial dysfunction has been identified as a critical factor in the pathogenesis and progression of eye disorders, making it a potential therapeutic target in the clinic. Natural products have been used in traditional medicine for centuries and continue to play a significant role in modern drug development and clinical therapeutics. Recently, there has been a surge in research exploring the efficacy of natural products in treating eye disorders and their underlying physiological mechanisms. This review aims to discuss the involvement of mitochondrial dysfunction in eye disorders and summarize the recent advances in the application of natural products targeting mitochondria. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products.

Revolutionizing eye care: the game-changing applications of nano-antioxidants in ophthalmology

Since the theory of free radical-induced aging was proposed in 1956, it has been constantly proven that reactive oxygen species (ROS) produced by oxidative stress play a vital role in the occurrence and progression of eye diseases. However, the inherent limitations of traditional drug therapy hindered the development of ophthalmic disease treatment. In recent years, great achievements have been made in the research of nanomedicine, which promotes the rapid development of safe theranostics in ophthalmology. In this review, we focus on the applications of antioxidant nanomedicine in the treatment of ophthalmology. The eye diseases were mainly classified into two categories: ocular surface diseases and posterior eye diseases. In each part, we first introduced the pathology of specific diseases about oxidative stress, and then presented the representative application examples of nano-antioxidants in eye disease therapy. Meanwhile, the nanocarriers that were used, the mechanism of function, and the therapeutic effect were also presented. Finally, we summarized the latest research progress and limitations of antioxidant nanomedicine for eye disease treatment and put forward the prospects of future development.

Epigallocatechin gallate delays age-related cataract development via the RASSF2/AKT pathway

Age-related cataract (ARC) is a common eye disease, the main cause of which is oxidative stress-mediated apoptosis of lens epithelial cells (LECs). Epigallocatechin gallate (EGCG) is the most potent antioxidant in green tea. Our results demonstrated that EGCG could effectively reduce apoptosis of LECs and retard lens clouding in aged mice. By comparing transcriptome sequencing results of three groups of mice (young control, untreated aged, and EGCG-treated) and screening using GO and KEGG analyses, we selected RASSF2 as the effector gene of EGCG for mechanistic exploration. We verified that the differential expression of RASSF2 was associated with the occurrence of ARC in clinical samples and mouse tissues by immunohistochemistry and western blotting, respectively. We showed that high RASSF2 expression plays a crucial role in the oxidative induction of apoptosis in LECs, as revealed by overexpression and interference experiments. Further studies showed that RASSF2 mediates the inhibitory effect of EGCG on apoptosis and ARCogenesis in LECs by regulating AKT (Ser473) phosphorylation. In this study, we found for the first time the retarding effect of EGCG on lens clouding in mice and revealed the mechanism of action of RASSF2/AKT in it, which provides a theoretical basis for the targeted treatment of EGCG.

Epigallocatechin-3-Gallate, an Active Green Tea Component to Support Anti-VEGFA Therapy in Wet Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a largely incurable disease and an emerging problem in aging societies. It occurs in two forms, dry and wet (exudative, neovascular), which may cause legal blindness and sight loss. Currently, there is not any effective treatment for dry AMD. Meanwhile, repeated intravitreal injections with antibodies effective against vascular endothelial growth factor A (VEGFA) slow down wet AMD progression but are not free from complications. (-)-Epigallocatechin-3-gallate (EGCG) is an active compound of green tea, which exerts many beneficial effects in the retinal pigment epithelium and the neural retina. It has been reported to downregulate the VEGFA gene by suppressing its activators. The inhibition of mitogen-activated protein kinases 1 and 3 (MAPK1 and MAPK3) may lie behind the antiangiogenic action of EGCG mediated by VEGFA. EGCG exerts protective effects against UV-induced damage to retinal cells and improves dysfunctional autophagy. EGCG may also interact with the mechanistic target rapamycin (MTOR) and unc-51-like autophagy activating kinase (ULK1) to modulate the interplay between autophagy and apoptosis. Several other studies report beneficial effects of EGCG on the retina that may be related to wet AMD. Therefore, controlled clinical trials are needed to verify whether diet supplementation with EGCG or green tea consumption may improve the results of anti-VEGFA therapy in wet AMD.

Oxidative Stress, Reductive Stress and Antioxidants in Vascular Pathogenesis and Aging

This review is focused on the mechanisms that regulate health, disease and aging redox status, the signal pathways that counteract oxidative and reductive stress, the role of food components and additives with antioxidant properties (curcumin, polyphenols, vitamins, carotenoids, flavonoids, etc.), and the role of the hormones irisin and melatonin in the redox homeostasis of animal and human cells. The correlations between the deviation from optimal redox conditions and inflammation, allergic, aging and autoimmune responses are discussed. Special attention is given to the vascular system, kidney, liver and brain oxidative stress processes. The role of hydrogen peroxide as an intracellular and paracrine signal molecule is also reviewed. The cyanotoxins β-N-methylamino-l-alanine (BMAA), cylindrospermopsin, microcystins and nodularins are introduced as potentially dangerous food and environment pro-oxidants.

Epigallocatechin-3-gallate ameliorates inflammatory injury caused by sepsis by regulating the lncRNA PVT1/miR-16-5p/TLR4 axis

BACKGROUND

Sepsis is identified as a severe inflammatory disease. Epigallocatechin-3-gallate (EGCG) has been reported to be a powerful anti-inflammatory chemical substance in numerous diseases. However, the underlying mechanism of the anti-inflammatory effects of EGCG in sepsis remains to be elucidated.

METHODS

The surgery for cecal ligation and puncture (CLP) was performed on male C57BL/6J mice aged 8 weeks. THP-1 cells were treated with 1 μg/ml lipopolysaccharide (LPS) for 24 h to imitate sepsis in vitro. Haematoxylene-Eosin (HE) staining of the sections of liver, lung and kidney was performed to evaluate the pathological changes. The inflammatory cytokines were quantitated by ELISA. qRT-PCR was performed to measure the expression levels of PVT1, miR-16-5p, and TLR4. The protein level of TLR4 was also assessed by Western blotting. Double luciferase reporter assay and RIP assay were performed to validate the interactions among PVT1, miR-16-5p, and TLR4.

RESULTS

EGCG inhibited the expression levels of PVT1 and TLR4 and enhanced miR-16-5p expression in CLP-operated mice and LPS-treated THP-1 cells. EGCG reduced the levels of inflammatory cytokines, which were restored by PVT1 overexpression. Mechanistically, PVT1 bound with miR-16-5p to activate TLR4 signaling. Further experiments demonstrated that miR-16-5p silencing or TLR4 overexpression antagonized sh-PVT1 or miR-16-5p mimics-mediated inhibitory effects on inflammatory cytokines, respectively. Knockdown of PVT1 alleviated inflammatory injury in CLP-induced sepsis in mice.

CONCLUSION

EGCG may effectively lower the levels of sepsis-induced inflammatory cytokines by targeting the PVT1/miR-16-5p/TLR4 axis.

Targeting Necroptosis: A Novel Therapeutic Option for Retinal Degenerative Diseases

The discovery of the necroptosis, a form of regulated necrosis that is mediated by receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed-lineage kinase domain-like pseudokinase (MLKL), represents a major breakthrough that has dramatically altered the conception of necrosis - traditionally thought of as uncontrolled cell death - in various human diseases. Retinal cell death is a leading cause of blindness and has been identified in most retinal diseases, e.g., age-related macular degeneration, glaucoma, retinal detachment, retinitis pigmentosa, etc. Increasing evidence demonstrates that retinal degenerative diseases also share a common mechanism in necroptosis. Exacerbated necroptotic cell death hinders the treatment for retinal degenerative diseases. In this review, we highlight recent advances in identifying retinal necroptosis, summarize the underlying mechanisms of necroptosis in retinal degenerative diseases, and discuss potential anti-necroptosis strategies, such as selective inhibitors and chemical agents, for treating retinal degenerative diseases.

New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance under Stress

Sleep, a conservative evolutionary behavior of organisms to adapt to changes in the external environment, is divided into natural sleep, in a healthy state, and sickness sleep, which occurs in stressful environments or during illness. Sickness sleep plays an important role in maintaining energy homeostasis under an injury and promoting physical recovery. Tea, a popular phytochemical-rich beverage, has multiple health benefits, including lowering stress and regulating energy metabolism and natural sleep. However, the role of tea in regulating sickness sleep has received little attention. The mechanism underlying tea regulation of sickness sleep and its association with the maintenance of energy homeostasis in injured organisms remains to be elucidated. This review examines the current research on the effect of tea on sleep regulation, focusing on the function of tea in modulating energy homeostasis through sickness sleep, energy metabolism, and damage repair in model organisms. The potential mechanisms underlying tea in regulating sickness sleep are further suggested. Based on the biohomology of sleep regulation, this review provides novel insights into the role of tea in sleep regulation and a new perspective on the potential role of tea in restoring homeostasis from diseases.

Epigallocatechin gallate as a nutraceutical to potentially target the metabolic syndrome: novel insights into therapeutic effects beyond its antioxidant and anti-inflammatory properties

Epigallocatechin gallate (EGCG) is one of the most abundant and powerful flavonoids contained in green tea. Because of the global increase in green tea consumption, there has been a general interest in understanding its health benefits, including its bioactive compounds like EGCG. Indeed, preclinical evidence already indicates that EGCG demonstrated a strong antioxidant and anti-inflammatory properties that could be essential in protecting against metabolic syndrome. The current review explores clinical evidence reporting on the beneficial effects of EGCG supplementation in obese subjects or patients with diverse metabolic complications that include type 2 diabetes and cardiovascular disease. The discussion incorporates the impact of different formulations of EGCG, as well as the effective doses and treatment duration. Importantly, besides highlighting the potential use of EGCG as a nutraceutical, the current review also discusses crucial evidence related to its pharmaceutical development as an agent to hinder metabolic diseases, including its bioavailability and metabolism profile, as well as its well-known biological properties.

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.

Epigallocatechin gallate enhances human lens epithelial cell survival after UVB irradiation via the mitochondrial signaling pathway

The aim of the present study was to explore the mechanism underlying the ultraviolet B (UVB) irradiation-induced apoptosis of human lens epithelial cells (HLECs), and to investigate the protective effect of epigallocatechin gallate (EGCG) against the UVB-induced apoptosis of HLECs. HLECs were exposed to different concentrations of EGCG plus UVB (30 mJ/cm²). Cell viability was determined using the MTT assay. Furthermore, mitochondrial membrane potential (Δψm) and apoptosis were assessed by flow cytometry with JC-1 and Annexin V/PI staining, respectively. Moreover, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), as well as the levels of GSH, hydrogen peroxide (H₂O₂) and hydroxyl free radicals were determined using biochemical assay techniques. Reverse transcription-quantitative PCR and western blotting were used to detect the mRNA and protein expression levels of Bcl-2, Bax, cytochrome c, caspase-9 and caspase-3, respectively. The results revealed that UVB irradiation reduced the Δψm of HLECs and induced apoptosis. Notably, EGCG significantly attenuated the generation of H₂O₂ and hydroxyl free radicals caused by UVB irradiation in HLECs, and significantly increased CAT, SOD and GSH-Px activities, however, the GSH levels were not significantly increased. EGCG also reduced UVB-stimulated Bax, cytochrome c, caspase-9 and caspase-3 expression, and elevated Bcl-2 expression, suggesting that EGCG may possess free radical-scavenging properties, thus increasing cell viability. In conclusion, EGCG may be able to protect against UVB-induced HLECs apoptosis through the mitochondria-mediated apoptotic signaling pathway, indicating its potential application in clinical practice.

Effects of Daily Melatonin Supplementation on Visual Loss, Circadian Rhythms, and Hepatic Oxidative Damage in a Rodent Model of Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases characterized by a progressive loss of visual function that primarily affect photoreceptors, resulting in the complete disorganization and remodeling of the retina. Progression of the disease is enhanced by increased oxidative stress in the retina, aqueous humor, plasma, and liver of RP animal models and patients. Melatonin has beneficial effects against age-related macular degeneration, glaucoma, and diabetic retinopathy, in which oxidative stress plays a key role. In the present study, we used the P23HxLE rat as an animal model of RP. Melatonin treatment (10 mg/kg b.w. daily in drinking water for 6 months) improved the parameters of visual function and decreased the rate of desynchronization of the circadian rhythm, both in P23HxLE and wild-type rats. Melatonin reduced oxidative stress and increased antioxidant defenses in P23HxLE animals. In wild-type animals, melatonin did not modify any of the oxidative stress markers analyzed and reduced the levels of total antioxidant defenses. Treatment with melatonin improved visual function, circadian synchronization, and hepatic oxidative stress in P23HxLE rats, an RP model, and had beneficial effects against age-related visual damage in wild-type rats.