Protection of retinal ganglion cells and retinal vasculature by Lycium barbarum polysaccharides in a mouse model of acute ocular hypertension

Lycium barbarum glycopeptide (wolfberry extract) slows N-methyl-N-nitrosourea-induced degradation of photoreceptors

JOURNAL/nrgr/04.03/01300535-202410000-00030/figure1/v/2024-02-06T055622Z/r/image-tiff Photoreceptor cell degeneration leads to blindness, for which there is currently no effective treatment. Our previous studies have shown that Lycium barbarum (L. barbarum) polysaccharide (LBP) protects degenerated photoreceptors in rd1, a transgenic mouse model of retinitis pigmentosa. L. barbarum glycopeptide (LbGP) is an immunoreactive glycoprotein extracted from LBP. In this study, we investigated the potential protective effect of LbGP on a chemically induced photoreceptor-degenerative mouse model. Wild-type mice received the following: oral administration of LbGP as a protective pre-treatment on days 1-7; intraperitoneal administration of 40 mg/kg N-methyl-N-nitrosourea to induce photoreceptor injury on day 7; and continuation of orally administered LbGP on days 8-14. Treatment with LbGP increased photoreceptor survival and improved the structure of photoreceptors, retinal photoresponse, and visual behaviors of mice with photoreceptor degeneration. LbGP was also found to partially inhibit the activation of microglia in N-methyl-N-nitrosourea-injured retinas and significantly decreased the expression of two pro-inflammatory cytokines. In conclusion, LbGP effectively slowed the rate of photoreceptor degeneration in N-methyl-N-nitrosourea-injured mice, possibly through an anti-inflammatory mechanism, and has potential as a candidate drug for the clinical treatment of photoreceptor degeneration.

Zeaxanthin dipalmitate-enriched wolfberry extract improves vision in a mouse model of photoreceptor degeneration

Zeaxanthin dipalmitate (ZD) is a chemical extracted from wolfberry that protects degenerated photoreceptors in mouse retina. However, the pure ZD is expensive and hard to produce. In this study, we developed a method to enrich ZD from wolfberry on a production line and examined whether it may also protect the degenerated mouse retina. The ZD-enriched wolfberry extract (ZDE) was extracted from wolfberry by organic solvent method, and the concentration of ZD was identified by HPLC. The adult C57BL/6 mice were treated with ZDE or solvent by daily gavage for 2 weeks, at the end of the first week the animals were intraperitoneally injected with N-methyl-N-nitrosourea to induce photoreceptor degeneration. Then optomotor, electroretinogram, and immunostaining were used to test the visual behavior, retinal light responses, and structure. The final ZDE product contained ~30mg/g ZD, which was over 9 times higher than that from the dry fruit of wolfberry. Feeding degenerated mice with ZDE significantly improved the survival of photoreceptors, enhanced the retinal light responses and the visual acuity. Therefore, our ZDE product successfully alleviated retinal morphological and functional degeneration in mouse retina, which may provide a basis for further animal studies for possible applying ZDE as a supplement to treat degenerated photoreceptor in the clinic.

Potential roles of dietary zeaxanthin and lutein in macular health and function

Lutein, zeaxanthin, and meso-zeaxanthin are three xanthophyll carotenoid pigments that selectively concentrate in the center of the retina. Humans cannot synthesize lutein and zeaxanthin, so these compounds must be obtained from the diet or supplements, with meso-zeaxanthin being converted from lutein in the macula. Xanthophylls are major components of macular pigments that protect the retina through the provision of oxidant defense and filtering of blue light. The accumulation of these three xanthophylls in the central macula can be quantified with non-invasive methods, such as macular pigment optical density (MPOD). MPOD serves as a useful tool for assessing risk for, and progression of, age-related macular degeneration, the third leading cause of blindness worldwide. Dietary surveys suggest that the dietary intakes of lutein and zeaxanthin are decreasing. In addition to low dietary intake, pregnancy and lactation may compromise the lutein and zeaxanthin status of both the mother and infant. Lutein is found in modest amounts in some orange- and yellow-colored vegetables, yellow corn products, and in egg yolks, but rich sources of zeaxanthin are not commonly consumed. Goji berries contain the highest known levels of zeaxanthin of any food, and regular intake of these bright red berries may help protect against the development of age-related macular degeneration through an increase in MPOD. The purpose of this review is to summarize the protective function of macular xanthophylls in the eye, speculate on the compounds' role in maternal and infant health, suggest the establishment of recommended dietary values for lutein and zeaxanthin, and introduce goji berries as a rich food source of zeaxanthin.

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.

RAGE and its ligand amyloid beta promote retinal ganglion cell loss following ischemia-reperfusion injury

Introduction

Glaucoma is a progressive neurodegenerative disease associated with age. Accumulation of amyloid-beta (Aß) proteins in the ganglion cell layer (GCL) and subsequent retinal ganglion cell (RGC) loss is an established pathological hallmark of the disease. The mechanism through which Aß provokes RGC loss remains unclear. The receptor for the advanced glycation end product (RAGE), and its ligand Aß, have been shown to mediate neuronal loss via internalizing Aß within the neurons. In this study, we investigated whether the RAGE-Aß axis plays a role in RGC loss in experimental glaucoma.

Methods

Retinal ischemia was induced by an acute elevation of intraocular pressure in RAGE^-/- and wild-type (WT) control mice. In a subset of animals, oligomeric Aß was injected directly into the vitreous of both strains. RGC loss was assessed using histology and biochemical assays. Baseline and terminal positive scotopic threshold (pSTR) were also recorded.

Results

Retinal ischemia resulted in 1.9-fold higher RGC loss in WT mice compared to RAGE^-/- mice (36 ± 3% p < 0.0001 vs. 19 ± 2%, p = 0.004). Intravitreal injection of oligomeric Aß resulted in 2.3-fold greater RGC loss in WT mice compared to RAGE^-/- mice, 7-days post-injection (55 ± 4% p = 0.008 vs. 24 ± 2%, p = 0.02). We also found a significant decline in the positive scotopic threshold response (pSTR) amplitude of WT mice compared to RAGE^-/- (36 ± 3% vs. 16 ± 6%).

Discussion

RAGE^-/- mice are protected against RGC loss following retinal ischemia. Intravitreal injection of oligomeric Aß accelerated RGC loss in WT mice but not RAGE^-/-. A co-localization of RAGE and Aß, suggests that RAGE-Aß binding may contribute to RGC loss.

Clinically relevant small-molecule promotes nerve repair and visual function recovery

Adult mammalian injured axons regenerate over short-distance in the peripheral nervous system (PNS) while the axons in the central nervous system (CNS) are unable to regrow after injury. Here, we demonstrated that Lycium barbarum polysaccharides (LBP), purified from Wolfberry, accelerated long-distance axon regeneration after severe peripheral nerve injury (PNI) and optic nerve crush (ONC). LBP not only promoted intrinsic growth capacity of injured neurons and function recovery after severe PNI, but also induced robust retinal ganglion cell (RGC) survival and axon regeneration after ONC. By using LBP gene expression profile signatures to query a Connectivity map database, we identified a Food and Drug Administration (FDA)-approved small-molecule glycopyrrolate, which promoted PNS axon regeneration, RGC survival and sustained CNS axon regeneration, increased neural firing in the superior colliculus, and enhanced visual target re-innervations by regenerating RGC axons leading to a partial restoration of visual function after ONC. Our study provides insights into repurposing of FDA-approved small molecule for nerve repair and function recovery.

Covalent Organic Framework (COF): A Drug and Carrier to Attenuate Retinal Ganglion Cells Death in an Acute Glaucoma Mouse Model

Purpose: We aim to investigate the use of covalent organic framework (COF) nanoparticles in the local treatment of glaucoma, both as a means of protecting retinal ganglion cells (RGCs), and as a carrier for delayed release of the medication rapamycin following a single intravitreal injection. Methods: a water-dispersible COF, and a COF-based nanoplatform for rapamycin release (COF-Rapa) was constructed. C57BL/6J mice were randomly divided into four groups: intravitreal injection of 1.5 µL normal saline (NS), COF (0.67 ng/µL), rapamycin (300 µM) or COF-Rapa (0.67 ng/µL-300 µM), respectively. The ischemia–reperfusion (I/R) model was established to mimic high intraocular pressure (IOP)-induced retinal injury in glaucoma. Labeling of RGCs by Fluoro-Gold and retinal electroretinogram were used to evaluate retinal function. Immunohistochemistry and Western blotting analyses of retinas were performed. Results: COF nanoparticles were delivered in vitro and in vivo. Six weeks after the COF injection, the number of RGCs was unaffected. In addition, the number of RBPMS-positive RGCs, GFAP-positive astrocytes and Iba1-positive microglia did not differ from the normal control. COF could effectively reduce RGCs death, improve phototransduction function and alleviate the overactivation of microglia compared to NS control after retinal I/R injury. Within six weeks, the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway in the retinas could be inhibited by a single intravitreal injection of COF-Rapa. Compared with single COF administration, COF-Rapa significantly reduced the inflammatory reaction after retinal I/R injury. Conclusions: COF may act as both an RGC protection agent and a carrier for prolonged rapamycin release. This research may lead to the development of novel RGC protection agents and drug delivery techniques, as well as the creation of multifunctional COF-based biomaterials for glaucoma retinopathy.

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.

Treatment of Glaucoma with Natural Products and Their Mechanism of Action: An Update

Glaucoma is one of the leading causes of irreversible blindness. It is generally caused by increased intraocular pressure, which results in damage of the optic nerve and retinal ganglion cells, ultimately leading to visual field dysfunction. However, even with the use of intraocular pressure-lowering eye drops, the disease still progresses in some patients. In addition to mechanical and vascular dysfunctions of the eye, oxidative stress, neuroinflammation and excitotoxicity have also been implicated in the pathogenesis of glaucoma. Hence, the use of natural products with antioxidant and anti-inflammatory properties may represent an alternative approach for glaucoma treatment. The present review highlights recent preclinical and clinical studies on various natural products shown to possess neuroprotective properties for retinal ganglion cells, which thereby may be effective in the treatment of glaucoma. Intraocular pressure can be reduced by baicalein, forskolin, marijuana, ginsenoside, resveratrol and hesperidin. Alternatively, Ginkgo biloba, Lycium barbarum, Diospyros kaki, Tripterygium wilfordii, saffron, curcumin, caffeine, anthocyanin, coenzyme Q10 and vitamins B3 and D have shown neuroprotective effects on retinal ganglion cells via various mechanisms, especially antioxidant, anti-inflammatory and anti-apoptosis mechanisms. Extensive studies are still required in the future to ensure natural products' efficacy and safety to serve as an alternative therapy for glaucoma.

Prebiotic effects of goji berry in protection against inflammatory bowel disease

The prevalence of inflammatory bowel disease (IBD) is increasing, which is concerning because IBD is a known risk factor for the development of colorectal cancer. Emerging evidence highlights environmental factors, particularly dietary factors and gut microbiota dysbiosis, as pivotal inducers of IBD onset. Goji berry, an ancient tonic food and a nutraceutical supplement, contains a range of phytochemicals such as polysaccharides, carotenoids, and polyphenols. Among these phytochemicals, L. barbarum polysaccharides (LBPs) are the most important functional constituents, which have protective effects against oxidative stress, inflammation, and neurodegeneration. Recently, the beneficial effects of goji berry and associated LBPs consumption were linked to prebiotic effects, which can prevent dysbiosis associated with IBD. This review assessed pertinent literature on the protective effects of goji berry against IBD focusing on the gut microbiota and their metabolites in mediating the observed beneficial effects.

Intravitreally Injected Methylene Blue Protects Retina against Acute Ocular Hypertension in Rats

Purpose: To assess the neuroprotective effects of methylene blue (MB) in a rat model of acute ocular hypertension (AOH) and explore its possible mechanisms.Methods: Our AOH rat model was obtained with anterior chamber perfusion for 60 min. After that, 100 μM MB was injected into the vitreous cavity immediately after injury. Electroretinogram, fundus photography, optical coherence tomography (OCT) and retina morphology examination were utilized to quantify retinal damage before surgery, as well as 7, 14 and 28 days after. The average number of surviving retinal ganglion cells (RGCs) was counted after fluorescent retrograde labelling with 4% DiI. And TUNEL assay was used to investigate retinal cell apoptosis at 24 hours after AOH. Nrf2 and BACE1 in the retina were determined by RT-qPCR analysis.Results: AOH did produce a severe degeneration effect on the whole retinal layer. Intravitreally injected MB maintained certain retinal thickness after AOH, reduced the destruction of electroretinograms, and enhanced RGCs survival. The average number of TUNEL-labelled cells statistically reduced in the MB-treated retina tissue compared with retina treated with normal saline. The relative mRNA level of Nrf2 was also much higher in the MB-treated retinas after AOH, and the expression of BACE1 had a decline in the AOH + MB group.Conclusions: MB can protect the retina from AOH injury and the possible mechanism might involve the inhibition of BACE1 expression and the activation of Nrf2 antioxidant pathway.

Wolfberry-derived zeaxanthin dipalmitate delays retinal degeneration in a mouse model of retinitis pigmentosa through modulating STAT3, CCL2 and MAPK pathways

Retinitis pigmentosa (RP) is a group of inherited photoreceptor degeneration diseases that causes blindness without effective treatment. The pathogenesis of retinal degeneration involves mainly oxidative stress and inflammatory responses. Zeaxanthin dipalmitate (ZD), a wolfberry-derived carotenoid, has anti-inflammatory and anti-oxidative stress effects. Here we investigated whether these properties of ZD can delay the retinal degeneration in rd10 mice, a model of RP, and explored its underlying mechanism. One shot of ZD or control vehicle was intravitreally injected into rd10 mice on postnatal day 16 (P16). Retinal function and structure of rd10 mice were assessed at P25, when rods degenerate substantially, using a visual behavior test, multi-electrode-array recordings and immunostaining. Retinal pathogenic gene expression and regulation of signaling pathways by ZD were explored using transcriptome sequencing and western blotting. Our results showed that ZD treatment improved the visual behavior of rd10 mice and delayed the degeneration of retinal photoreceptors. It also improved the light responses of photoreceptors, bipolar cells and retinal ganglion cells. The expression of genes that are involved in inflammation, apoptosis and oxidative stress were up-regulated in rd10 mice, and were reduced by ZD. ZD further reduced the activation of two key factors, signal transducer and activator of transcription 3 and chemokine (C-C motif) ligand 2, down-regulated the expression of the inflammatory factor GFAP, and inhibited extracellular signal regulated protein kinases and P38, but not the JNK pathways. In conclusion, ZD delays the degeneration of the rd10 retina both morphologically and functionally. Its anti-inflammatory function is mediated primarily through the signal transducer and activator of transcription 3, chemokine (C-C motif) ligand 2 and MAPK pathways. Thus, ZD may serve as a potential clinical candidate to treat RP.

Immune activities of polysaccharides isolated from Lycium barbarum L. What do we know so far?

Lycium barbarum is widely used as a functional food and medicinal herb to promote health and longevity in China and in some other Asian countries. In modern pharmacological and chemical studies, the most valuable and well-researched component of L. barbarum is a group of unique water-soluble glycoconjugates that are collectively termed Lycium barbarum polysaccharides (LBPs). Numerous modern pharmacological studies have revealed that LBPs possess antiaging, antidiabetic, antifibrotic, neuroprotective, and immunomodulation properties, while the immunomodulatory effect is primary and is involved in other activities. However, due to their structural heterogeneity and lack of chromophores, it has long been unclear how LBPs work on the immune system. A few studies have recently provided some insights into the proposed mode of action of LBPs, such as structure-activity relationships, receptor recognition, and gut microbiota modulation of LBPs. This review provides a comprehensive overview of the immunoregulating properties of LBPs and their related mechanisms of action.

Involvement of the NLRC4 inflammasome in promoting retinal ganglion cell death in an acute glaucoma mouse model

PURPOSE

To explore the role of nucleotide-binding oligomerization domain-like receptors (NLRs) family caspase-activation and the recruitment domain containing 4 (NLRC4) inflammasome in retinal ganglion cell (RGC) injury induced by an acute glaucoma mouse model.

METHOD

A mouse model of acute ocular hypertension, which can lead to retinal ischemia-reperfusion (I/R) injury, was established. The expression level of NLRC4 was detected by polymerase chain reaction and western blotting. Localized expression of NLRC4 was detected by examining immunofluorescence in eyeball sections. Intravitreal adeno-associated virus 2(AAV2) administration was used to knockdown retinal Nlrc4. Fluoro-Gold labeled RGCs and TdT-mediated dUTP nick end labeling were used to evaluate the survival and apoptosis of RGCs. Tlr4^-/- mice were utilized to explore whether NLRC4 inflammasome is influenced by Toll-like receptor4 (TLR4).

RESULTS

NLRC4, expressed in RGCs and microglial cells, was actively involved in mouse retinal I/R injury. Knockdown of Nlrc4 using an AAV2 vector caused an obvious reduction in the generation of IL-1β led by the rapidly elevated intraocular pressure, and thereby improved the RGC survival. In addition, activation of the NLRC4 inflammasome could influence the phosphorylation of p38 and Jun N-terminal kinase, which was largely dependent on TLR4 signaling.

CONCLUSION

Our study demonstrated the role of NLRC4 inflammasome in promoting RGC damage in mouse retinal I/R injury. Inhibition of NLRC4 might be leveraged as a potential therapeutic target in glaucomatous retinopathy.

The neuroprotective effect of submicron and blended Lycium barbarum for experiment retinal ischemia and reperfusion injury in rats

The purpose of this study was to investigate the neuroprotective potential of submicron (milled) and blended Lycium barbarum (LB) in glaucomatous retinal neuropathy using a rat model of high intraocular pressure (HIOP) induced retinal ischemia. The rats were treated with 500, 250, 100 mg/kg LB (submicron or blended form) orally once daily for 56 days respectively after 1 week of retinal ischemia induction. We conducted electroretinography (ERG), histopathological analysis in retina and antioxidative level assays, such as total glutathione (GSH (glutathione) + reduced glutathione) + GSSH (glutathione disulfide), catalase activity, SOD (superoxide dismutase) activity, and lipid peroxidant malondialdehyde (MDA) in the retina and plasma of test rats. The results indicated that the amplitudes of a and b wave of ERG were preserved in rats treated with submicron and blended LB groups, the best protective effect on ERG b wave amplitudes was observed at the dosage of 250 mg/kg of both forms of LB. Retinal thickness was best preserved, particularly significant in the retinal inner nuclear layer in submicron 250 mg/kg LB group. The levels of antioxidant GSSH+GSH, SOD and catalase activity in the retina were higher in blended 500 mg/kg and submicron 250 mg/kg groups than other groups, while the MDA level was lower in submicron LB groups than that in blended LB and non-LB IR group. In the plasma, there was no significant difference in the levels of GSSH+GSH and catalase activity between treated groups, but higher levels of SOD and lower levels of MDA were observed in 250 mg/kg submicron and 500 mg/kg submicron LB groups than the blended LB and non-LB IR groups. Generally better antioxidative effects were observed in the submicron LB than blended LB among treated groups, especially the 250 mg/kg submicron LB, providing good retinal neuroprotection by preserving retinal structure and function with improved antioxidative capacity. The submicron LB may have clinical implication as an adjuvant therapy of oxidative stress and retinal damage caused by HIOP induced retinal ischemia and reperfusion injury.

Natural Products: Evidence for Neuroprotection to Be Exploited in Glaucoma

Glaucoma, a leading cause of irreversible blindness worldwide, is an optic neuropathy characterized by the progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) is recognized as the main risk factor. Despite effective IOP-lowering therapies, the disease progresses in a significant number of patients. Therefore, alternative IOP-independent strategies aiming at halting or delaying RGC degeneration is the current therapeutic challenge for glaucoma management. Here, we review the literature on the neuroprotective activities, and the underlying mechanisms, of natural compounds and dietary supplements in experimental and clinical glaucoma.

Activation of Sirtuin1 by lyceum barbarum polysaccharides in protection against diabetic cataract

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum polysaccharide (LBP) extracted from the Lycium barbarum L. has been widely used to improve diabetes and its relative complications. However, the mechanisms have not fully understood. A recent study has demonstrated that LBP upregulates suituin 1 (SIRT1).

OBJECTIVE

This study was to define the role of Sirt1 and its downstream signaling pathways in diabetic cataract using in vitro and in vivo models.

MATERIALS AND METHODS

Human lens epithelial cell line SRA01/04 cells were cultured under high glucose (HG) medium with treatment of LBP or vehicle. Cell viability, apoptosis, protein and/or mRNA levels of Sirt1, BAX, Bcl-2, active-caspase-3, FOXO1, p27 and acetylated p53 were measured. SIRT1 upregulated- and knocked-down cells were generated and tested in high glucose culture. Diabetes mellitus was induced in rats by streptozotocin injection. Body weight, blood glucose levels, lens transparency and retinal function were assessed and SIRT1, as well as the aforementioned biomarkers were measured using Western blotting and qPCR in the animal lens samples.

RESULTS

The results showed that HG decreased cell viability and LBP prevented the decrease. The reduced viability in HG cultured SRA01/04 cells was associated with increased levels of BAX, active caspase 3, FOXO1, p27, and p53 and decreased levels of SIRT1 and Bcl-2. Further experiments using sirt1 gene modulated cells showed that upregulation of Sirt1 improved viability, increase cell division as reflected by an increased proportion of S phase in the cell cycle, reduced the number of apoptotic cell death and suppressed p53 acetylation and caspase 3 activation. Opposite results were observed in SIRT1 knock-down cells. Treating diabetic animals with LBP reduced body weight loss and blood glucose content in diabetic animals. Similarly, LBP hindered the development of cataract in lenses and improved retinal function. The beneficial effect of LBP on diabetic cataract was associated with the supression of p53, caspase 3, FOXO1, BAX, p27 and elevation of SIRT1 and Bcl-2, which were consistent with the in vitro findings.

CONCLUSION

Our findings showed that diabetes caused cataract is associated with suppression of SIRT1 and Bcl-2 and activation of other cell death related genes. LBP prevented diabetic cataract in animals by upregulating Sirt1 and Bcl-2 and suppressing cell death related genes.

Lycium barbarum polysaccharides related RAGE and Aβ levels in the retina of mice with acute ocular hypertension and promote maintenance of blood retinal barrier

Our previous study verified the protective effects of Lycium barbarum polysaccharides (LBP) on retinal neurons and blood vessels in acute ocular hypertension (AOH) mice. To investigate the effect of LBP on the reactivity of retinal glial cells, an AOH mouse model was established in one eye by maintaining ocular hypertension of 90 mmHg for 60 minutes. Either LBP solution (1 mg/kg) or phosphate-buffered saline was administrated to the mice by gavage daily, starting 7 days before the AOH insult and continuing until the mice were sacrificed for specimen collection on day 4 post-insult. After AOH insult, increased numbers of astrocytes and microglia were observed, together with decreased expression of the following glial cell biomarkers in the retinal ganglion cells of AOH mice: glial fibrillary acidic protein, glutamine synthetase, aquaporin-4, S-100 proteins, ionized calcium-binding adaptor molecule 1, amyloid precursor protein and receptor of advanced glycosylation end-products. After intervention with LBP, the above changes were significantly reduced. Remarkably, morphological remodeling of blood vessel-associated retinal astrocytes, marked by glial fibrillary acidic protein, was also observed. These results, taken together, suggest that LBP regulated the production of amyloid-β and expression of receptor of advanced glycosylation end-products, as well as mediating the activity of retinal glial cells, which may lead to the promotion of better maintenance of the blood-retinal barrier and improved neuronal survival in AOH insult. This study was approved by the Committee for the Use of Live Animals in Teaching and Research (approval No. CULTRA-#1664-08).

Systematic Review on Therapeutic Strategies to Minimize Corneal Stromal Scarring After Injury

OBJECTIVES

To evaluate recent studies on available and experimental therapies in preventing or minimizing corneal stromal scarring after injury.

METHODS

We performed an Entrez PubMed literature search using keywords "cornea," "scarring," "haze," "opacity," "ulcer," "treatments," "therapies," "treatment complications," and "pathophysiology" resulting in 390 articles of which 12 were analyzed after filtering, based on English language and publication within 8 years, and curation for relevance by the authors.

RESULTS

The 12 articles selected included four randomized control trials (RCTs) (two were double-blinded placebo-controlled RCTs, one was a prospective partially masked RCT, and one was an open-label RCT), two retrospective observational studies, and six laboratory-based studies including two studies having in vivo and in vitro experiments, one was in vivo study, one was ex vivo study, and the last two were in vitro studies. The current mainstay for preventing or minimizing corneal scarring involves the use of topical corticosteroids and local application of mitomycin C. However, supportive evidence for their use in clinical practice from well-designed RCTs is lacking. Laboratory studies on topical rosiglitazone therapy, vitamin C prophylaxis, gene therapy, and stem cell therapy have shown promising results but have yet to be translated to clinical research.

CONCLUSION

There is a need for more robust randomized controlled trials to support treatments using topical corticosteroids and mitomycin C. Furthermore, their clinical efficacy and safety profile should be compared with new treatments that have shown promising results in the laboratory setting. Ultimately, the goal should be to personalize cornea scarring treatment according to the most effective treatment for the specific underlying pathology.

Posttreatment Intervention With Lycium Barbarum Polysaccharides is Neuroprotective in a Rat Model of Chronic Ocular Hypertension

Purpose

To investigate the neuroprotective effects of Lycium barbarum polysaccharides (LBP) against chronic ocular hypertension (OHT) in rats and to consider if effects differed when treatment was applied before (pretreatment) or during (posttreatment) chronic IOP elevation.

Methods

Sprague-Dawley rats (10-weeks old) underwent suture implantation around the limbus for 15 weeks (OHT) or 1 day (sham). Four experimental groups were studied, three OHT groups (n = 8 each) treated either with vehicle (PBS), LBP pretreatment or posttreatment, and a sham control (n = 5) received no treatment. LBP (1 mg/kg) pre- and posttreatment were commenced at 1 week before and 4 weeks after OHT induction, respectively. Treatments continued up through week 15. IOP was monitored twice weekly for 15 weeks. Optical coherence tomography and ERG were measured at baseline, week 4, 8, 12, and 15. Eyes were collected for ganglion cell layer (GCL) histologic analysis at week 15.

Results

Suture implantation successfully induced approximately 50% IOP elevation and the cumulative IOP was similar between the three OHT groups. When compared with vehicle control (week 4: -23 ± 5%, P = 0.03), LBP pretreatment delayed the onset of retinal nerve fiber layer (RNFL) thinning (week 4, 8: -2 ± 7%, -11 ± 3%, P > 0.05) and arrested further reduction up through week 15 (-10 ± 4%, P > 0.05). LBP posttreatment intervention showed no significant change in rate of loss (week 4, 15: -25 ± 4.1%, -28 ± 3%). However, both LBP treatments preserved the retinal ganglion cells (RGC) and retinal functions up to week 15, which were significantly reduced in vehicle control.

Conclusions

LBP posttreatment arrested the subsequent neuronal degeneration after treatment commencement and preserved RGC density and retinal functions in a chronic OHT model, which was comparable with pretreatment outcomes.

Role of EGFR/ErbB2 and PI3K/AKT/e-NOS in Lycium barbarum polysaccharides Ameliorating Endothelial Dysfunction Induced by Oxidative Stress

Lycium barbarum polysaccharides (LBP) are the major ingredients of wolfberry. In this study, we investigated the role of LBP in endothelial dysfunction induced by oxidative stress and the underlying mechanisms using thoracic aortic endothelial cells of rat (RAECs) as a model. We found that Ang II inhibits cell viability of RAECs with 10-6mol/L of Ang II treatment for 24h most potential (P<0.05), the level of reactive oxygen species (ROS) is increased by Ang II treatment (P<0.01), and the expression of Occludin and Zonula occludens-1 (ZO-1) is decreased by Ang II treatment (P<0.05). However, preincubation of cells with LBP could inhibit the changes caused by Ang II, LBP increased cell viability (P<0.05), decreased the level of ROS (P<0.01), and up-regulated the expression of Occludin (P<0.05) and ZO-1. In addition, Ang II treatment increased the expression of EGFR and p-EGFR (Try1172) and which can be inhibited by LBP. On the contrary, expression of ErbB2, p-ErbB2 (Try1248), PI₃K, p-e-NOS (Ser1177) (P<0.05), and p-AKT (Ser473) (P<0.05) was inhibited by Ang II treatment and which can be increased by LBP. Treatment of the cells with inhibitors showed that the regulation of p-e-NOS and p-AKT expression by Ang II and LBP can be blocked by PI₃K inhibitor wortmannin but not EGFR and ErbB2 inhibitor AC480. Taken together, our results suggested that LBP plays a critical role in maintaining the integrality of blood vessel endothelium through reduced production of ROS via regulating the activity of EGFR, ErbB2, PI₃K/AKT/e-NOS, and which may offer a novel therapeutic option in the management of endothelial dysfunction.

Lycium Barbarum Polysaccharides Rescue Neurodegeneration in an Acute Ocular Hypertension Rat Model Under Pre- and Posttreatment Conditions

Purpose

To investigate the posttreatment neuronal rescue effects of Lycium barbarum polysaccharides (LBP) in an acute ocular hypertensive (AOH) model.

Methods

Intraocular pressure (IOP) was elevated manometrically to 80 mm Hg (AOH) or 15 mm Hg (sham) for 120 minutes in adult Sprague-Dawley rats. Five experimental groups were considered: Three AOH groups were pretreated with PBS (vehicle) (n = 9), LBP 1 mg/kg (n = 8), or 10 mg/kg (n = 13), and one AOH group was posttreated with LBP 10 mg/kg (n = 8), once daily. The sham cannulation group (n = 5) received no treatment. Pretreatments commenced 7 days before and posttreatment 6 hours after AOH, and continued up through postcannulation day 28. All the animals underwent optical coherence tomography and electroretinogram measurements at baseline and postcannulation days 10 and 28. The ganglion cell layer (GCL) densities were quantified at day 28.

Results

Both inner retinal layer thickness (IRLT) and positive scotopic threshold response (pSTR) underwent significant reduction (≥50% of thickness and amplitude) in the vehicle group (P < 0.05). Pretreatment with LBP 1 and 10 mg/kg retained 77 ± 11% and 89 ± 8% of baseline IRLT, respectively, and preserved pSTR functions. The posttreatment group showed a significant reduction in IRLT (-35 ± 8%, P < 0.001) and pSTR (∼48% of baseline, P < 0.001) on day 10. By day 28, there was an improvement in functional pSTR (∼72% of baseline, P > 0.05) with no significant further thinning (-40 ± 8%, P = 0.15) relative to day 10. GCL density was reduced in vehicle control (P = 0.0001), but did not differ between sham and pre- and posttreated AOH groups.

Conclusions

The rescue effect of LBP posttreatment was observed later, which arrested the secondary degeneration and improved the retinal function.

Vagal Nerve Stimulation Attenuates Ischemia-Reperfusion Induced Retina Dysfunction in Acute Ocular Hypertension

Purpose: The present study aimed to investigate whether cervical vagal nerve stimulation (VNS) could prevent retinal ganglion cell (RGC) loss and retinal dysfunction after ischemia/reperfusion (I/R) injury.

Methods: First, rats were randomly divided into sham group (n = 4) and VNS group (n = 12). Activation of the nodose ganglia (NOG), nucleus of the solitary tract (NTS), superior salivatory nucleus (SSN), and pterygopalatine ganglion (PPG) neural circuit were evaluated by c-fos expression at 0 h after sham VNS and at 0 h (n = 4), 6 h (n = 4), 72 h (n = 4) after VNS. Secondly, rats were randomly assigned to I/R group (pressure-induced retinal ischemia for 1 h and reperfusion for 1 h in the right eye, n = 16) and I/R+VNS group (right cervical VNS for 2 h during the I/R period, n = 16). The left eye of each rat served as a control. Electroretinogram (ERG), RGC numbers, tumor necrosis factor-α (TNF-α) and vasoactive intestinal polypeptide (VIP) levels in retina were determined. Additionally, the level of VIP in PPG was evaluated.

Results: In the first part of the study, compared with the sham group, the VNS group exhibited significantly increased expression of c-fos in NOG, NTS, SSN, and PPG tissues at 0, 6, and 72 h. In the second part of the study, compared with left eyes, retinal function in right eyes (as assessed by the a-wave, b-wave and the oscillatory potential amplitudes of ERG and RGC data) was significantly decreased by I/R. The decreased retinal function was attenuated by VNS. In addition, I/R induced an increase in inflammation, which was reflected by elevated TNF-α expression in the retina. VNS significantly attenuated the increase in I/R-induced inflammation. Moreover, VIP expression in the retina and PPG, which may contribute to the inhibition of the inflammatory response, was significantly increased after VNS.

Conclusion: VNS could protect against retinal I/R injury by downregulating TNF-α. Upregulation of VIP expression due to activation of the NOG-NTS-SSN-PPG neural circuit may underlie to the protective effects of VNS.

Goji Berries as a Potential Natural Antioxidant Medicine: An Insight into Their Molecular Mechanisms of Action

Goji berries (Lycium fruits) are usually found in Asia, particularly in northwest regions of China. Traditionally, dried goji berries are cooked before they are consumed. They are commonly used in Chinese soups and as herbal tea. Moreover, goji berries are used for the production of tincture, wine, and juice. Goji berries are high antioxidant potential fruits which alleviate oxidative stress to confer many health protective benefits such as preventing free radicals from damaging DNA, lipids, and proteins. Therefore, the aim of the review was to focus on the bioactive compounds and pharmacological properties of goji berries including their molecular mechanisms of action. The health benefits of goji berries include enhancing hemopoiesis, antiradiation, antiaging, anticancer, improvement of immunity, and antioxidation. There is a better protection through synergistic and additive effects in fruits and herbal products from a complex mixture of phytochemicals when compared to one single phytochemical.

Lycium Barbarum Polysaccharides Protect Retina in rd1 Mice During Photoreceptor Degeneration

Purpose

As an active component in wolfberry, lycium barbarum polysaccharides (LBP) are capable of protecting retinal neurons in several animal disease models. Here, we asked whether LBP rescues the retinal morphology and function in rd1 mouse, a photoreceptor fast-degenerating animal model of retinitis pigmentosa, and in particular focused on LBP's effects on the function of retinal ganglion cells (RGCs) during photoreceptor degeneration.

Methods

An equal volume of LBP or control vehicle was daily intraperitoneal (i.p.) injected in rd1 mice from postnatal day 4 (P4) to P14, P20, or P24 when photoreceptors completely degenerate. Immunostaining, electroretinogram (ERG), visual behavior tests and multielectrode array (MEA) recordings were assessed to determine the structure and function of the treated retina.

Results

LBP treatment greatly promoted photoreceptor survival, enhanced ERG responses, and improved visual behaviors in rd1 mice. MEA data showed that LBP treatment in general decreased the abnormally high spontaneous spiking that occurs in rd1 mice, and increased the percentage of light-responsive RGCs as well as their light-evoked response, light sensitivity, signal-to-noise ratio, and response speed. Interestingly, LBP treatment affected ON and OFF responses differently.

Conclusions

LBP improves retinal morphology and function in rd1 mice, and delays the functional decay of RGCs during photoreceptor degeneration. This is the first study that has examined in detail the effects of LBP on RGC responses. Our data suggest that LBP may help extend the effective time window before more invasive RP therapeutic approaches such as retinoprosthesis are applied.

The Nrf2 Signaling in Retinal Ganglion Cells under Oxidative Stress in Ocular Neurodegenerative Diseases

Retinal ganglion cells (RGCs) are one of the important cell types affected in many ocular neurodegenerative diseases. Oxidative stress is considered to be involved in retinal RGCs death in ocular neurodegenerative diseases. More and more attention has been focused on studying the agents that may have neuroprotective effects. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a key nuclear transcription factor for the systemic antioxidant defense system. This review elucidates the underlying mechanism of the Nrf2-mediated neuroprotective effects on RGCs in ocular neurodegenerative diseases, such as diabetic retinopathy and retinal ischemia-reperfusion injury. Several Nrf2 inducers that shield RGCs from oxidative stress-induced neurodegeneration via regulating Nrf2 signaling are discussed.

Low-dose minocycline mediated neuroprotection on retinal ischemia-reperfusion injury of mice

PURPOSE

The aim of this study was to investigate the effect of minocycline (MC) on the survival of retinal ganglion cells (RGCs) in an ischemic-reperfusion (I/R) injury model of retinal degeneration.

METHODS

Retinal I/R injury was induced in the left eye of mice for 60 min by maintaining intraocular pressure at 90 mmHg. Low- or high-dose MC (20 or 100 mg/kg, respectively) was administered by intravenous injection at 5 min after the retinal ischemic insult and then administered once daily until the mice were euthanized. RGCs and microglial cells were counted using immunofluorescence staining. Functional changes in the RGCs were evaluated using electroretinography. The visual function was assessed using an optokinetic test.

RESULTS

The data demonstrated that the effect of MC was dose dependent. Low-dose MC showed protective effects, with reduced RGC loss and microglial activation, while the high-dose MC showed damage effects, with more RGC loss and microglial activation when compared with the vehicle group. The electroretinography and optokinetic test results were consistent with the morphologic observations.

CONCLUSIONS

These data suggested that appropriate concentrations of MC can protect the retina against retinal ischemic-reperfusion injury, while excessive MC has detrimental effects.

Transcorneal Electrical Stimulation Inhibits Retinal Microglial Activation and Enhances Retinal Ganglion Cell Survival After Acute Ocular Hypertensive Injury

PURPOSE

To investigate the effect of transcorneal electrical stimulation (TcES) on retinal ganglion cell (RGC) function and survival after acute ocular hypertension-related retinal injury in gerbil eyes.

METHODS

Gerbil eyes were subjected to acute ocular hypertensive injury (80 mm Hg for 60 minutes). In the treatment group, TcES was applied to the surgical eye immediately and then twice weekly for a total of 1 month. In the control group, sham TcES was given to the surgical eye at the same time points. Retinal function was assessed and compared between groups using flash electroretinography. For histological analysis, the number of RGC and microglial cells were counted by immunofluorescence staining after the gerbils were sacrificed on day 7 and day 28. Real-time polymerase chain reaction and western blot analysis were conducted to compare expression of interleukin (IL)-10, IL-6, COX-2, tumor necrosis factor (TNF)-α, and NF-κB phosphorylation among groups.

RESULTS

TcES-treated eyes had significantly higher RGC survival at 1 month compared to controls. This was associated with RGC function. Furthermore, TcES-treated eyes were shown to have increased IL-10 expression, with a corresponding reduction in IL-6 and COX-2 expression as well as reduction in NF-κB phosphorylation. This was associated with a suppression in microglial cell activation in TcES-treated eyes.

CONCLUSIONS

Early treatment with TcES in gerbils protected the RGC from secondary damage and preserved retinal function in acute ocular hypertensive injury through modulation of the microglial-cell activated local inflammatory response.

TRANSLATIONAL RELEVANCE

Our study strengthens the argument for translating TcES as a viable treatment in acute glaucoma.

Demystifying traditional Chinese medicines: Lycium barbarum as a model therapeutic

The practice of Traditional Chinese Medicine (TCM) focuses on holistic treatment of the body. This often includes preparation and application of medicinal herbs, either alone or in combination with other supplements. Lycium barbarum (LB), for example, is a commonly used herbal supplement in many Asian countries, being most well-known for improving kidney, liver, and eye health. It is also one of the most widely scientifically researched TCMs and a large body of literature is available describing its effects on various tissues and organ systems. In this perspective, we briefly expand upon how LB can be used as a model TCM in the systematic study of other herbal medicines, highlighting two of the primary barriers to their use in modern medicine worldwide.

The genus Lycium as food and medicine: A botanical, ethnobotanical and historical review

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium is widely distributed in the arid to semi-arid environments of North and South America, Africa, and Eurasia. In recent years, Lycium barbarum and L. chinense have been advertised as "superfood" with healthy properties. Despite of its popularity, there is a lack of an integrated and critical appraisal of the existing evidence for the use of Lycium.

AIM OF THE STUDY

There is a need to understand: 1) Which species were used and how the uses of Lycium developed spatially and over time, 2) how uses differ among regions with different culture backgrounds, and 3) how traditional and current therapeutic and preventive health claims correlate with pharmacological findings.

METHODS

Information was retrieved from floras, taxonomic, botanical, and ethnobotanical databases, research articles, recent editions of historical Chinese herbals over the last 2000 years, and pharmacopoeias.

RESULTS

Of totally 97 species, 31 have recorded uses as food and/or medicine worldwide. Usually the fruits are used. While 85% of the Lycium species occur in the Americas and Africa, 26% of them are used, but 9 out of 14 species in Eurasia. In China, seven species and two varieties of the genus Lycium occur, of which four species have been used by different ethnic groups. Only L. barbarum and L. chinense have been transformed into globally traded commodities. In China, based on the name "", their use can be traced back over the last two millennia. Lycium fruits for anti-aging, improving eyesight and nourishment were documented already in 500C.E. (Mingyi Bielu). Recent findings explain the pharmacological foundations of the traditional uses. Especially polysaccharides, zeaxanthin dipalmitate, vitamins, betaine, and mixed extracts were reported to be responsible for anti-aging, improving eyesight, and anti-fatigue effects.

CONCLUSIONS

The integration of historical, ethnobotanical, botanical, phytochemical and pharmacological data has enabled a detailed understanding of Lycium and its wider potential. It highlights that the focus so far has only been on two species and that the genus can potentially yield a wide range of other products with different properties.

Rational Basis for Nutraceuticals in the Treatment of Glaucoma

BACKGROUND

Glaucoma, the second leading cause of blindness worldwide, is a chronic optic neuropathy characterized by progressive retinal ganglion cell (RGC) axons degeneration and death. Primary open-angle glaucoma (OAG), the most common type, is often associated with increased intraocular pressure (IOP), however other factors have been recognized to partecipate to the patogenesis of the optic neuropathy. IOP-independent mechanisms that contribute to the glaucoma-related neurodegeneration include oxidative stress, excitotoxicity, neuroinflammation, and impaired ocular blood flow. The involvement of several and diverse factors is one of the reasons for the progression of glaucoma observed even under efficient IOP control with the currently available drugs.

METHODS

Current research and online content related to the potential of nutritional supplements for limiting retinal damage and improving RGC survival is reviewed.

RESULTS

Recent studies have suggested a link between dietary factors and glaucoma risk. Particularly, some nutrients have proven capable of lowering IOP, increase circulation to the optic nerve, modulate excitotoxicity and promote RGC survival. However, the lack of clinical trials limit their current therapeutic use. The appropriate use of nutraceuticals that may be able to modify the risk of glaucoma may provide insight into glaucoma pathogenesis and decrease the need for, and therefore the side effects from, conventional therapies.

CONCLUSION

The effects of nutrients with anti-oxidant and neuroprotective properties are of great interest and nutraceuticals may offer some therapeutic potential although a further rigorous evaluation of nutraceuticals in the treatment of glaucoma is needed to determine their safety and efficacy.

Investigation of the neuroprotective effects of Lycium barbarum water extract in apoptotic cells and Alzheimer's disease mice

Alzheimer's disease (AD) affects people worldwide and is caused by chronic and progressive damage to the central nervous system. Lycium barbarum (LB), a renowned functional food and medicinal plant in Southeast Asia, may possess protective effects against nerve injury. The present study aimed to investigate the neuroprotective effects of LB water extract in a differentiated (D)PC12 cellular apoptosis model induced by L-glutamic acid (L-Glu), and a mouse model of AD, induced by the combination of AlCl₃ and D-galactose. LB markedly increased DPC12 cell survival against L-Glu induced damage by increasing cell viability, reducing the apoptosis rate and G1 phase arrest, suppressing intracellular reactive oxygen species accumulation, blocking Ca²⁺ overload and preventing mitochondrial membrane potential depolarization. LB additionally normalized the expression levels of apoptosis regulator Bcl-2, apoptosis regulator BAX, and cleaved caspase-3, −8 and −9 in L-Glu exposed cells. In the AD mouse model, LB increased the amount of horizontal and vertical movement in the autonomic activity test, improved endurance time in the rotarod test and decreased escape latency time in the Morris water maze test. Additionally, the levels of acetylcholine and choline acetyltransferase were significantly increased in the serum and hypothalamus in the LB-treated AD mice. These data suggested that LB may exert neuroprotective effects and may aid in preventing neurodegenerative disease.

Effects of Lycium barbarum (goji berry) on dry eye disease in rats

Lycium barbarum (goji berry) has long been used as a food and traditional herbal medicine. This study aimed to investigate the beneficial effect of the goji berry on dry eye disease in rats. Male Sprague-Dawley rats with induced dry eye disease were randomly assigned to four groups: Vehicle (control), low-dose goji berry extract [GBE; 250 mg/kg/body weight (bw)], median-dose GBE (350 mg/kg/bw), and high-dose GBE (500 mg/kg/bw). Three methods, Schirmer's test, tear break-up time (BUT) measurement and keratoconjunctival fluorescein staining, were used to evaluate the effect of GBE on symptoms of dry eye disease experienced by the rats. The results of the present study revealed that both the Schirmer's test score and tear BUT significantly increased following 1 week of GBE administration. Furthermore, the severity of the keratoconjunctival staining decreased significantly. In addition, the results suggested that administration of GBE may ameliorate dry eye disease symptoms in a dose-dependent manner. There were no mortalities and no apparent abnormal histopathology changes in the liver or kidney tissues of rats administered GBE for 21 consecutive days. Polysaccharides and betaine present in GBE may have important effects in alleviating dry eye disease induced by oxidative stress and inflammation. In conclusion, the goji berry is a safe, functional food with beneficial effects in alleviating dry eye disease.

Protective Effect of Prunus Cerasus (Sour Cherry) Seed Extract on the Recovery of Ischemia/Reperfusion-Induced Retinal Damage in Zucker Diabetic Fatty Rat

Among diabetes patients, ophthalmological complications are very frequent. High blood glucose and (consequential) ischemia-reperfusion (I/R) injury contribute significantly to the severity of retinopathies. Diabetic retinopathy is among the leading causes of blindness. Our study demonstrates the effect of sour cherry seed extract (SCSE) on blood glucose and function of the retina with electroretinography (ERG) in a diabetic setting with or without ischemia-reperfusion (I/R) injury in Zucker Diabetic Fatty (ZDF) rats. Our results prove that the SCSE has a retinoprotective effect in diabetic rats: according to ERG measurements, SCSE treatment mitigated the retinal function-damaging effect of diabetes, and proved to be protective in the diabetic eye against ischemia-reperfusion injuries of the retina. Outcomes suggest that the protective effects of SCSE may occur through several pathways, including HO-1 dependent mechanisms. The observation that SCSE treatment decreases blood glucose is also novel. These findings offer the possibility for development of novel therapeutic strategies utilizing this emerging functional food, in particular in the prevention of conditions resulting from high blood glucose or I/R injury, such as deterioration of retinal microcirculation.

Neuroprotective Mechanisms of Lycium barbarum Polysaccharides Against Ischemic Insults by Regulating NR2B and NR2A Containing NMDA Receptor Signaling Pathways

Glutamate excitotoxicity plays an important role in neuronal death after ischemia. However, all clinical trials using glutamate receptor inhibitors have failed. This may be related to the evidence that activation of different subunit of NMDA receptor will induce different effects. Many studies have shown that activation of the intrasynaptic NR2A subunit will stimulate survival signaling pathways, whereas upregulation of extrasynaptic NR2B will trigger apoptotic pathways. A Lycium barbarum polysaccharide (LBP) is a mixed compound extracted from Lycium barbarum fruit. Recent studies have shown that LBP protects neurons against ischemic injury by anti-oxidative effects. Here we first reported that the effect of LBP against ischemic injury can be achieved by regulating NR2B and NR2A signaling pathways. By in vivo study, we found LBP substantially reduced CA1 neurons from death after transient global ischemia and ameliorated memory deficit in ischemic rats. By in vitro study, we further confirmed that LBP increased the viability of primary cultured cortical neurons when exposed to oxygen-glucose deprivation (OGD) for 4 h. Importantly, we found that LBP antagonized increase in expression of major proteins in the NR2B signal pathway including NR2B, nNOS, Bcl-2-associated death promoter (BAD), cytochrome C (cytC) and cleaved caspase-3, and also reduced ROS level, calcium influx and mitochondrial permeability after 4 h OGD. In addition, LBP prevented the downregulation in the expression of NR2A, pAkt and pCREB, which are important cell survival pathway components. Furthermore, LBP attenuated the effects of a NR2B co-agonist and NR2A inhibitor on cell mortality under OGD conditions. Taken together, our results demonstrated that LBP is neuroprotective against ischemic injury by its dual roles in activation of NR2A and inhibition of NR2B signaling pathways, which suggests that LBP may be a superior therapeutic candidate for targeting glutamate excitotoxicity for the treatment of ischemic stroke.

Zeaxanthin dipalmitate alleviates hepatic injury induced by superimposed chronic hepatitis B and non-alcoholic steatohepatitis in non-obese mice

A hepatitis B virus (HBV) transgenic mice model was used to establish the fatty liver superimposed model by feeding the methionine choline-deficient (MCD) diet for 8 weeks, with or without the gavage of 2 mg/kg zeaxanthin dipalmitate (ZD) three times per week. Both wild-type and HBV transgenic mice, with MCD diet, gained typical non-obese non-alcoholic steatohepatitis (NASH) and HBV symptoms. Coadministration with ZD exhibited evident therapeutic effects through alleviating those pathological events. Moreover, long-term vehicle-ZD treatment was found to be safe. Thus, ZD is a promising and safe hepato-protective agent against hepatic injury induced by superimposed HBV and NASH in non-obese mice.

Targets of Neuroprotection in Glaucoma

Progressive neurodegeneration of the optic nerve and the loss of retinal ganglion cells is a hallmark of glaucoma, the leading cause of irreversible blindness worldwide, with primary open-angle glaucoma (POAG) being the most frequent form of glaucoma in the Western world. While some genetic mutations have been identified for some glaucomas, those associated with POAG are limited and for most POAG patients, the etiology is still unclear. Unfortunately, treatment of this neurodegenerative disease and other retinal degenerative diseases is lacking. For POAG, most of the treatments focus on reducing aqueous humor formation, enhancing uveoscleral or conventional outflow, or lowering intraocular pressure through surgical means. These efforts, in some cases, do not always lead to a prevention of vision loss and therefore other strategies are needed to reduce or reverse the progressive neurodegeneration. In this review, we will highlight some of the ocular pharmacological approaches that are being tested to reduce neurodegeneration and provide some form of neuroprotection.

A novel RIPK1 inhibitor that prevents retinal degeneration in a rat glaucoma model

In glaucoma, retinal ganglion cells (RGCs) are exposed to ischemic stress with elevation of the intraocular pressure and are subsequently lost. Necroptosis, a type of regulated necrosis, is known to play a pivotal role in this loss. We observed that receptor-interacting protein kinase 1 (RIPK1), the key player of necroptosis, was activated by diverse ischemic stresses, including TCZ, chemical hypoxia (CH), and oxygen glucose deprivation (OGD). In this study, we introduce a RIPK1-inhibitory compound (RIC) with a novel scaffold. RIC inhibited downstream events following RIPK1 activation, including necrosome formation and mitochondrial dysfunction in RGC5 cells. Moreover, RIC protected RGCs against ischemic injury in the rat glaucoma model, which was induced by acute high intraocular pressure. However, RIC displayed biochemical characteristics that are distinct from those of previous RIPK1 inhibitors (necrostatin-1; Nec-1 and Compound 27; Cpd27). RIC protected RGCs against OGD insult, while Nec-1 and Cpd27 did not. Conversely, Nec-1 and Cpd27 protected RGCs from TNF-stimulated death, while RIC failed to inhibit the death of RGCs. This implies that RIPK1 activates alternative pathways depending on the context of the ischemic insults.

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.

Lycium barbarum polysaccharide inhibits gastric cancer cell proliferation, migration and invasion by down-regulation of MMPs and suppressing epithelial-mesenchymal transition

OBJECTIVE

To evaluate the effect of Lycium barbarum polysaccharide (LBP) on gastric cancer (GC) cells and to explore the associated mechanism.

METHODS

Human GC SGC-7901 cells were divided into control, 10 μM LBP, 20 μM LBP and 50 μM LBP groups. CCK8 assay and Transwell assay were performed to evaluate the proliferation, migration and invasion of SGC-7901 cells. Western blotting was used to determine protein expressions.

RESULTS

The proliferation, migration and invasion decreased significantly in 20 μM LBP and 50 μM LBP groups. As the result of Western blotting, protein levels of MMP2, MMP9, Snail and vimentin decreased in 20 μM LBP and 50 μM LBP groups with different degrees. The expression E-cadherin significantly increased in all three experimental groups. The phosphorylation levels of AKT and PI3K in 20 μM LBP and 50 μM LBP groups were much lower than control group.

CONCLUSION

LBP could inhibit the proliferation, migration and invasion of human GC cells bydown-regulation of MMPs and suppression of epithelial-mesenchymal transition (EMT).

Effects of Lycium barbarum on the Visual System

Lycium barbarum (wolfberry, gogi berry, gouqizi, ) is one of the most widely used Chinese herbal medicines (CHMs) and is also one of the most scientifically studied. Indeed, the polysaccharide component of this berry (LBP) has been shown to have antioxidant, antiinflammatory, antiexcitotoxic, and antiapoptotic properties. These properties make it a particularly useful treatment option for the ocular environment. Although there are a handful of studies investigating the use of LBP to treat diseases affecting the lens, the vast majority of the published literature investigating LBP in the visual system focus on the retina. In this chapter, we have described what is currently understood concerning the effects of LBP treatment on various retinal diseases, including glaucoma, ischemia/reperfusion, age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy. We then describe the functions attributed to LBP using other cellular contexts to elucidate the full mechanisms this CHM utilizes in the retina. By making connections between what is known about the function of LBP in a variety of tissues and its function as a therapy for retinal degenerative diseases, we hope to further emphasize the continued use of this CHM in clinical medicine in addition to providing a platform for additional study.

α-Aminoadipic acid protects against retinal disruption through attenuating Müller cell gliosis in a rat model of acute ocular hypertension

OBJECTIVE

Ocular hypertension is an important risk factor for glaucoma. The purpose of this study was to investigate the gliotoxic effects of α-aminoadipic acid (AAA) in a rat model of AOH and its underlying mechanisms.

MATERIALS AND METHODS

In the rat model of acute ocular hypertension (AOH), intraocular pressure was increased to 110 mmHg for 60 minutes. Animals were divided into four groups: sham operation (Ctrl), AOH, AOH + phosphate-buffered saline (PBS), and AOH + AAA. Cell apoptosis in the ganglion cell layer was detected with the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) assay, and retinal ganglion cells (RGCs) immunostained with Thy-1 were counted. Müller cell activation was detected using immunostaining with glutamine synthetase and glial fibrillary acidic protein. Tumor necrosis factor-α (TNF-α) was examined using Western blot.

RESULTS

In the rat model of AOH, cell apoptosis was induced in the ganglion cell layer and the number of RGCs was decreased. Müller cell gliosis in the retinas of rats was induced, and retinal protein levels of TNF-α were increased. Intravitreal treatment of AAA versus PBS control attenuated these retinal abnormalities to show protective effects in the rat model of AOH.

CONCLUSION

In the retinas of the rat model of AOH, AAA treatment attenuated retinal apoptosis in the ganglion cell layer and preserved the number of RGCs, likely through the attenuation of Müller cell gliosis and suppression of TNF-α induction. Our observations suggest that AAA might be a potential therapeutic target in glaucoma.

Lycium barbarum polysaccharides attenuates N-methy-N-nitrosourea-induced photoreceptor cell apoptosis in rats through regulation of poly (ADP-ribose) polymerase and caspase expression

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum L., popularly known as "Goji berry", a classic of Traditional Chinese Medicine has long been used to treat ocular diseases and cardiovascular diseases. Recently, the photoreceptor cell protection of Lycium barbarum polysaccharides (LBP), a water extract from Lycium barbarum L. has received more attention. The present study was designed to investigate the effect of LBP on N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis, and the involvement of the poly (ADP-ribose) polymerase (PARP) and caspase.

MATERIALS AND METHODS

Photoreceptor cell injury was induced in male Sprague-Dawley rats by an intraperitoneal injection of MNU 60mg/kg. Seven days prior to MNU injection, LBP were intragastrical administered daily, rats were sacrificed at 24h and 7 days after MNU injection. Retinal morphologies, photoreceptor cells apoptosis, and protein expression were evaluated at 24h and 7 days after MNU injection.

RESULTS

Morphologically, the outer nuclear layer was well preserved in the LBP-treated rat retinas throughout the experimental period. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) assays showed that LBP could significantly suppress the loss of photoreceptor cells, as determined by the photoreceptor cell ratio at the central retina 24h and 7 days after MNU administration. Western-blot analysis demonstrated the expression levels of procaspase-9, -7, -3 and cleaved caspase-9, -7, -3 were upregulated, and PARP were downregulated both 24h and 7 days after MNU injection. LBP treatment significantly decreased protein levels of procaspase and cleaved caspase, increased the level of PARP and cleaved PARP on 24h and 7 days.

CONCLUSIONS

LBP inhibits MNU-induced rat photoreceptor cell apoptosis and protects retinal structure via the regulation of the expressions of PARP and caspase.

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.