Lycium barbarum polysaccharides protected human retinal pigment epithelial cells against oxidative stress-induced apoptosis

Retinal ischemia-reperfusion injury and pretreatment with Lycium barbarum glycopeptide

AIM

To investigate the antioxidant protective effect of Lycium barbarum glycopeptide (LbGP) pretreatment on retinal ischemia-reperfusion (I/R) injury (RIRI) in rats.

METHODS

RIRI was induced in Sprague Dawley rats through anterior chamber perfusion, and pretreatment involved administering LbGP via gavage for 7d. After 24h of reperfusion, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine (CREA) levels, retinal structure, expression of Caspase-3 and Caspase-8, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) in the retina were measured.

RESULTS

The pretreatment with LbGP effectively protected the retina and retinal tissue from edema and inflammation in the ganglion cell layer (GCL) and nerve fiber layer (NFL) of rats subjected to RIRI, as shown by light microscopy and optical coherence tomography (OCT). Serum AST was higher in the model group than in the blank group (P=0.042), but no difference was found in ALT, AST, and CREA across the LbGP groups and model group. Caspase-3 expression was higher in the model group than in the blank group (P=0.006), but no difference was found among LbGP groups and the model group. Caspase-8 expression was higher in the model group than in the blank group (P=0.000), and lower in the 400 mg/kg LbGP group than in the model group (P=0.016). SOD activity was lower in the model group than in the blank group (P=0.001), and the decrease was slower in the 400 mg/kg LbGP group than in the model group (P=0.003). MDA content was higher in the model group than in the blank group (P=0.001), and lower in the 400 mg/kg LbGP group than in the model group (P=0.016). The pretreatment with LbGP did not result in any observed liver or renal toxicity in the model.

CONCLUSION

LbGP pretreatment exhibits dose-dependent anti-inflammatory, and antioxidative effects by reducing Caspase-8 expression, preventing declines of SOD activity, and decreasing MDA content in the RIRI rat model.

Distinct Role of Lycium barbarum L. Polysaccharides in Oxidative Stress-Related Ocular Diseases

Oxidative stress is an imbalance between the increased production of reactive species and reduced antioxidant activity, which can cause a variety of disturbances including ocular diseases. Lycium barbarum polysaccharides (LBPs) are complex polysaccharides isolated from the fruit of L. barbarum, showing distinct roles in antioxidants. Moreover, it is relatively safe and non-toxic. In recent years, the antioxidant activities of LBPs have attracted remarkable attention. In order to illustrate its significance and underlying therapeutic value for vision, we comprehensively review the recent progress on the antioxidant mechanisms of LBP and its potential applications in ocular diseases, including diabetic retinopathy, hypertensive neuroretinopathy, age-related macular degeneration, retinitis pigmentosa, retinal ischemia/reperfusion injury, glaucoma, dry eye syndrome, and diabetic cataract.

Effects of Lycium barbarum L. Polysaccharides on Vascular Retinopathy: An Insight Review

Vascular retinopathy is a pathological change in the retina caused by ocular or systemic vascular diseases that can lead to blurred vision and the risk of blindness. Lycium barbarum polysaccharides (LBPs) are extracted from the fruit of traditional Chinese medicine, L. barbarum. They have strong biological activities, including immune regulation, antioxidation, and neuroprotection, and have been shown to improve vision in numerous studies. At present, there is no systematic literature review of LBPs on vascular retinal prevention and treatment. We review the structural characterization and extraction methods of LBPs, focus on the mechanism and pharmacokinetics of LBPs in improving vascular retinopathy, and discuss the future clinical application and lack of work. LBPs are involved in the regulation of VEGF, Rho/ROCK, PI3K/Akt/mTOR, Nrf2/HO-1, AGEs/RAGE signaling pathways, which can alleviate the occurrence and development of vascular retinal diseases in an inflammatory response, oxidative stress, apoptosis, autophagy, and neuroprotection. LBPs are mainly absorbed by the small intestine and stomach and excreted through urine and feces. Their low bioavailability in vivo has led to the development of novel dosage forms, including multicompartment delivery systems and scaffolds. Data from the literature confirm the medicinal potential of LBPs as a new direction for the prevention and complementary treatment of vascular retinopathy.

Current Advances in Mechanisms and Treatment of Dry Eye Disease: Toward Anti-inflammatory and Immunomodulatory Therapy and Traditional Chinese Medicine

Dry eye is currently one of the most common ocular surface disease. It can lead to ocular discomfort and even cause visual impairment, which greatly affects the work and quality of life of patients. With the increasing incidence of dry eye disease (DED) in recent years, the disease is receiving more and more attention, and has become one of the hot research fields in ophthalmology research. Recently, with the in-depth research on the etiology, pathogenesis and treatment of DED, it has been shown that defects in immune regulation is one of the main pathological mechanisms of DED. Since the non-specific and specific immune response of the ocular surface are jointly regulated, a variety of immune cells and inflammatory factors are involved in the development of DED. The conventional treatment of DED is the application of artificial tears for lubricating the ocular surface. However, for moderate-to-severe DED, treatment with anti-inflammatory drugs is necessary. In this review, the immunomodulatory mechanisms of DED and the latest research progress of its related treatments including Chinese medicine will be discussed.

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

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

Natural Ingredients from Medicine Food Homology as Chemopreventive Reagents against Type 2 Diabetes Mellitus by Modulating Gut Microbiota Homoeostasis

Type 2 diabetes mellitus (T2DM) is a noteworthy worldwide public health problem. It represents a complex metabolic disorder, mainly characterized as hyperglycemia and lipid dysfunction. The gut microbiota dysbiosis has been proposed to play a role in the development of diabetes. Recently, there has been considerable interest in the use of medicine food homology (MFH) and functional food herbs (FF) to ameliorate diabetes and lead to a natural and healthy life. Hence, this review compiles some reports and findings to demonstrate that the practical use of the MFH/FF can modulate the homoeostasis of gut microbiota, thereby ameliorating the development of T2DM. The results provided useful data to support further investigation of the functional basis and application of MFH/FF to treat T2DM through maintaining intestinal homeostasis.

Exploration of the Effect and Mechanism of Fructus Lycii, Rehmanniae Radix Praeparata, and Paeonia lactiflora in the Treatment of AMD Based on Network Pharmacology and in vitro Experimental Verification

Purpose

The aim of this study was to observe the mechanism of Fructus Lycii (FL), Rehmanniae Radix Praeparata (RRP) and Paeonia lactiflora (PL) in treating age-related macular degeneration (AMD) based on network pharmacology and biological experiments.

Methods

Bioactive compounds, potential targets of FL, RRP and PL, and genes related to AMD, were acquired from public databases. Functional and pathway enrichment analyses of the core targets were conducted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Subsequently, the finding was further verified with cell experiments. The MTT assay and flow cytometric analysis were used to assess cell viability and apoptosis. The production of reactive oxygen species (ROS) was analyzed by DCFH-DA staining; the activity of antioxidant enzymes was chemically measured with assay kits. The expression of key proteins was evaluated by Western blot analysis.

Results

Fifty-nine active compounds, 182 potential targets, and 2536 AMD-related human genes were identified. A total of 103 key targets of the three herbs on AMD were identified by protein-protein interaction (PPI) analysis. The abovementioned targets were correlated with nuclear receptor activity, oxidative stress, and apoptosis pathways according to the GO and KEGG analyses. MTT assay and flow cytometry demonstrated that pretreatment of ARPE-19 cells with the three herbs significantly increased cell viability and decreased apoptosis induced by H₂O₂. The three herbs might reduce the intracellular ROS levels and increase the SOD and CAT activities after H₂O₂. Furthermore, the three herbs significantly inhibited oxidative stress via increasing the expression of Nrf2, HO-1 and NQO1.

Conclusion

The combined results of network pharmacology and validation experiments showed that FL, RRP and PL reduce oxidative stress and apoptosis in RPE cells to exert its effect in the treatment of AMD.

Fructus lycii: A Natural Dietary Supplement for Amelioration of Retinal Diseases

Fructus lycii (F. lycii) is an exotic "berry-type" fruit of the plant Lycium barbarum that is characterized by a complex mixture of bioactive compounds distinguished by their high antioxidant potential. F. lycii is used in traditional Chinese home cooking and in the Chinese Pharmacopeia as an aid to vision and longevity as well as a remedy for diabetes to balance "yin" and "yang" in the body for about two centuries. Although a myriad of bioactive compounds have been isolated from F. lycii, polysaccharides, carotenoids, flavonoids, and phenolics represent the key functional components of F. lycii. F. lycii has been shown to exhibit a wide range of biological activities in experimental settings including antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects. Despite its medicinal role dating back to the eighteenth century in the Far East and robust evidence of beneficial effects on ocular health and retinal diseases originating mainly from studies in animal models, the role of F. lycii in the clinical management of retinal diseases is yet to be established. This article comprehensively reviews the literature germane to F. lycii and retinal diseases with particular emphasis on age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa, which are commonly seen in clinical practice.

Inhibitory effect of Lycium barbarum polysaccharide on sperm damage during cryopreservation

With the development of cryopreservation technology, marked progress has been made regarding sperm cryopreservation. However, as conventional cryopreservation agents are not effective at freezing weak sperm, improved cryopreservation agents are in demand. In the present study, the addition of Lycium barbarum polysaccharides to glycerol-egg-yolk-citrate sperm cryopreservation agent was determined to improve sperm forward speed, reduce the DNA fragmentation index and improve the mitochondrial membrane potential. Furthermore, during the freezing and thawing of sperm, the improved cryopreservative increased the content of Bcl-2 while reducing the content of Bax, cytochrome C and caspase-3. These results indicated that polysaccharides added as a protective agent preserved the normal function of sperm mitochondria. Transmission electron microscopy also confirmed the protective effect of the polysaccharides on the structure of mitochondria. It was also indicated that improved cryopreservative lowered the levels of reactive oxygen species (ROS) during the freeze-thawing process. Therefore, it is hypothesized that improved cryopreservative agents may be beneficial for maintaining the structure and function of the mitochondria of weak sperm when cryopreserved, which may be facilitated via reducing the production of ROS in the freezing-thawing process, thus avoiding activation of the apoptotic pathway in sperm mitochondria and protecting mitochondrial structure and sperm function.

Genome-wide meta-analysis identifies novel loci associated with age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among the elderly population. To accelerate the understanding of the genetics of AMD, we conducted a meta-analysis of genome-wide association studies (GWAS) combining data from the International AMD Genomics Consortium AMD-2016 GWAS (16,144 advanced AMD cases and 17,832 controls), AMD-2013 GWAS (17,181 cases and 60,074 controls), and new data on 4017 AMD cases and 14,984 controls from Genetic Epidemiology Research on Aging study. We identified 12 novel AMD loci near or within C4BPA-CD55, ZNF385B, ZBTB38, NFKB1, LINC00461, ADAM19, CPN1, ACSL5, CSK, RLBP1, CLUL1, and LBP. We then replicated the associations of the novel loci in independent cohorts, UK Biobank (5860 cases and 126,726 controls) and FinnGen (1266 cases and 47,560 control). In general, the concordance in effect sizes was very high (correlation in effect size estimates 0.89), 11 of 12 novel loci were in the expected direction, 5 were associated with AMD at a nominal significance level, and rs3825991 (near gene RLBP1) after Bonferroni correction. We identified an additional 21 novel genes using a gene-based test. Most of the novel genes are expressed in retinal tissue and could be involved in the pathogenesis of AMD (i.e., complement, inflammation, and lipid pathways). These findings enhance our understanding of the genetic architecture of AMD and shed light on the biological process underlying AMD pathogenesis.

Lycium barbarum polysaccharides protects retinal ganglion cells against oxidative stress injury

The accumulation of excessive reactive oxygen species can exacerbate any injury of retinal tissue because free radicals can trigger lipid peroxidation, protein damage and DNA fragmentation. Increased oxidative stress is associated with the common pathological process of many eye diseases, such as glaucoma, diabetic retinopathy and ischemic optic neuropathy. Many studies have demonstrated that Lycium barbarum polysaccharides (LBP) protects against oxidative injury in numerous cells and tissues. For the model of hypoxia we used cultured retinal ganglion cells and induced hypoxia by incubating with 200 µM cobalt chloride (CoCl₂) for 24 hours. To investigate the protective effect of LBP and its mechanism of action against oxidative stress injury, the retinal tissue was pretreated with 0.5 mg/mL LBP for 24 hours. The results of flow cytometric analysis showed LBP could effectively reduce the CoCl₂-induced retinal ganglion cell apoptosis, inhibited the generation of reactive oxygen species and the reduction of mitochondrial membrane potential. These findings suggested that LBP could protect retinal ganglion cells from CoCl₂-induced apoptosis by reducing mitochondrial membrane potential and reactive oxygen species.

Extraction, Structural Characterization, and Biological Functions of Lycium Barbarum Polysaccharides: A Review

Lycium barbarum polysaccharides (LBPs), as bioactive compounds extracted from L. barbarum L. fruit, have been widely explored for their potential health properties. The extraction and structural characterization methods of LBPs were reviewed to accurately understand the extraction method and structural and biological functions of LBPs. An overview of the biological functions of LBPs, such as antioxidant function, antitumor activity, neuroprotective effects, immune regulating function, and other functions, were summarized. This review provides an overview of LBPs and a theoretical basis for further studying and extending the applications of LBPs in the fields of medicine and food.

Lycium barbarum polysaccharides protect human trophoblast HTR8/SVneo cells from hydrogen peroxide‑induced oxidative stress and apoptosis

Pregnancy complications are associated with abnormal cytotrophoblast differentiation and invasion. Hydrogen peroxide (H₂O2) is an important mediator of oxidative ischemia/reperfusion stress in the placenta. Lycium barbarum polysaccharides (LBP) have been demonstrated to counteract oxidative free radicals. The effects of LBP in trophoblast HTR8/SVneo cells injured with H2O2 were examined. A cell counting kit-8 assay was performed to detect the effect of LBP at different concentrations on the proliferative ability of H2O2 injured trophoblast cells. Flow cytometry was used to determine the levels of reactive oxygen species (ROS), mitochondria membrane potential (MMP) disruption and apoptosis. Superoxide dismutase (SOD) activity and lactate dehydrogenase (LDH) leakage into the supernatant was detected by ultraviolet spectrophotometry. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to detect the expression of apoptosis-associated factors, including survivin, hypoxia inducible factor 1-α (HIF1-α), Bcl-2 apoptosis regulator (Bcl-2), Bcl-2 associated X apoptosis regulator (Bax). The results revealed that LBP protected the proliferative ability of trophoblast cells injured with H2O2 in a dose-dependent manner. LBP inhibited the oxidative stress induced by H2O2, by reducing ROS and LDH levels and increasing SOD activity. Additionally, LBP decreased MMP disruption and cell apoptosis induced by H2O2, by increasing the mRNA and protein expression of survivin, HIF1-α and Bcl-2 and decreasing Bax expression. Therefore, it was concluded that LBP protected human trophoblast cells from H2O2-induced oxidative stress and cell apoptosis via regulation of apoptosis-associated factor expression. It will provide a novel strategy for the treatment of pregnancy complications.

Lycium barbarum Polysaccharides Protect Rat Corneal Epithelial Cells against Ultraviolet B-Induced Apoptosis by Attenuating the Mitochondrial Pathway and Inhibiting JNK Phosphorylation

Lycium barbarum polysaccharides (LBPs) have been shown to play a key role in protecting the eyes by reducing the apoptosis induced by certain types of damage. However, it is not known whether LBPs can protect damaged corneal cells from apoptosis. Moreover, no reports have focused on the role of LBPs in guarding against ultraviolet B- (UVB-) induced apoptosis. The present study aimed to investigate the protective effect and underlying mechanism of LBPs against UVB-induced apoptosis in rat corneal epithelial (RCE) cells. The results showed that LBPs significantly prevented the loss of cell viability and inhibited cell apoptosis induced by UVB in RCE cells. LBPs also inhibited UVB-induced loss of mitochondrial membrane potential, downregulation of Bcl-2, and upregulation of Bax and caspase-3. Finally, LBPs attenuated the phosphorylation of c-Jun NH₂-terminal kinase (JNK) triggered by UVB. In summary, LBPs protect RCE cells against UVB-induced damage and apoptosis, and the underlying mechanism involves the attenuation of the mitochondrial apoptosis pathway and the inhibition of JNK phosphorylation.

Effect of Lycium bararum polysaccharides on methylmercury-induced abnormal differentiation of hippocampal stem cells

The aim of the present study was to observe the effects of a general extract of Lycium bararum polysaccharides (LBPs) on methylmercury (MeHg)-induced damage in hippocampus neural stem cells (hNSCs). The hippocampal tissues of embryonic day 16 Sprague-Dawley rats were extracted for the isolation, purification and cloning of hNSCs. Following passage and proliferation for 10 days, the cells were allocated at random into the following groups: Control, LBPs, MeHg and MeHg + LBPs. MTT and microtubule-associated protein 2 (MAP-2)/glial fibrillary acidic protein/Hoechst immunofluorescence tests were performed to detect the differentiation and growth of hNSCs in the various groups. The differentiation rate of MeHg-treated hNSCs and the perimeter of MAP-2-positive neurons were 3.632±0.63% and 62.36±5.58 µm, respectively, significantly lower compared with the control group values of 6.500±0.81% and 166±8.16 µm (P<0.05). Furthermore, the differentiation rate and the perimeter of MAP-2-positive neurons in LBPs groups cells was 7.75±0.59% and 253.3±11.21 µm, respectively, significantly higher compared with the control group (P<0.05). The same parameters in the MeHg + LBPs group were 5.92±0.98% and 111.9±6.07 µm, respectively, significantly higher than the MeHg group (P<0.05). The astrocyte differentiation rates in the MeHg and MeHg + LBPs group were 41.19±2.14 and 34.58±1.70, respectively (P<0.05). These results suggest that LBPs may promote the generation and development of new neurons and inhibit the MeHg-induced abnormal differentiation of astrocytes. Thus, LBPs may be considered to be a potential new treatment for MeHg-induced neurotoxicity in hNSCs.

Neuro-protective Mechanisms of Lycium barbarum

Neuronal diseases, including retinal disorders, stroke, Alzheimer's disease, Parkinson's disease and spinal cord injury, affect a large number of people worldwide and cause heavy social and economic burdens. Although many efforts have been made by scientists and clinicians to develop novel drug and healthcare strategies, few of them received satisfactory outcomes to date. Lycium barbarum is a traditional homology of medicine and food in Chinese medicine, with the capability to nourish the eyes, liver and kidneys. Recent studies have also explored its powerful neuro-protective effects on a number of neuronal diseases. In the current review, we collected key recent findings regarding the neuro-protective effects and mechanisms of L. barbarum derivatives, primarily its polysaccharide (LBP) , in some common diseases of the nervous system. A comprehensive comparison with currently available drugs has also been discussed. In general, LBP is a promising neuronal protector with potent ameliorative effects on key pathological events, such as oxidative stress, inflammation, apoptosis and cell death with minimal side effects.