Algae Oil Treatment Protects Retinal Ganglion Cells (RGCs) via ERK Signaling Pathway in Experimental Optic Nerve Ischemia

Docosahexaenoic Acid Reduced Vascular Endothelial Cell Injury in Diabetic Rats Via the Modulation of Autophagy

Purpose

Among varied ω-3 polyunsaturated fatty acid types, the therapeutic properties of docosahexaenoic acid (DHA) have been indicated under diabetic conditions in different cell lineages. Here, we investigated the anti-diabetic properties of DHA in rats with type 2 diabetes mellitus (D2M) focusing on autophagy-controlling factors.

Methods

D2M was induced in male Wistar rats using a single dose of streptozocin (STZ) and a high-fat diet for 8 weeks. On week 2, diabetic rats received DHA 950 mg/kg/d until the end of the study. After that, rats were euthanized, and aortic and cardiac tissue samples were stained with H&E staining for histological assessment. The expression of adhesion molecules, ICAM-1 and VCAM-1, was measured in heart samples using real-time PCR analysis. Using western blotting, protein levels of BCLN1, LC3, and P62 were measured in D2M rats pre- and post-DHA treatment.

Results

Data showed intracellular lipid vacuoles inside the vascular cells, and cardiomyocytes, after induction of D2M and DHA reduced intracellular lipid droplets and in situ inflammatory response. DHA can diminish increased levels of ICAM-1 in diabetic conditions (P Control vs. D2M rats=0.005) and reach near-to-control values (P Control vs. D2M rats=0.28; P D2M rats vs. D2M rats+DHA=0.033). Based on western blotting, D2M slightly increased the BCLN1 and LC3-II/I ratio without affecting P62. DHA promoted the LC3II/I ratio (P=0.303) and reduced P62 (P Control vs. D2M rats+DHA =0.0433; P D2M vs. D2M rats+DHA=0.096), leading to the completion of autophagy flux under diabetic conditions.

Conclusion

DHA can reduce lipotoxicity of cardiovascular cells possibly via the activation of adaptive autophagy response in D2D rats.

Visual fatigue a comprehensive review of mechanisms of occurrence, animal model design and nutritional intervention strategies

When the eyes work intensively, it is easy to have eye discomfort such as blurred vision, soreness, dryness, and tearing, that is, visual fatigue. Visual fatigue not only affects work and study efficiency, but long-term visual fatigue can also easily affect physical and mental health. In recent years, with the popularization of electronic products, although it has brought convenience to the office and study, it has also caused more frequent visual fatigue among people who use electronic devices. Moreover, studies have reported that the number of people with visual fatigue is showing a trend of increasing year by year. The range of people involved is also extensive, especially students, people who have been engaged in computer work and fine instruments (such as microscopes) for a long time, and older adults with aging eye function. More and more studies have proposed that supplementation with the proper nutrients can effectively relieve visual fatigue and promote eye health. This review discusses the physiological mechanisms of visual fatigue and the design ideas of animal experiments from the perspective of modern nutritional science. Functional food ingredients with the ability to alleviate visual fatigue are discussed in detail.

Neuroprotective Strategies for Nonarteritic Anterior Ischemic Optic Neuropathy: A Systematic Review

PURPOSE

Nonarteritic anterior ischemic optic neuropathy (NAION) is the second most common form of optic neuropathy. Most patients show no improvement over time. Until now, there is still no definitive therapy for NAION. The available literatures on the possible treatment of NAION are quite diverse and controversial. Neuroprotection strategies have been suggested as one of the potential treatments for NAION. This review aims to critically evaluate the literature on neuroprotective strategy for NAION.

METHODS

This report was written in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. We performed a systematic literature search in Pubmed, Science Direct, Proquest, and Cochrane databases. Only neuroprotective agents that directly work in protecting neurons were included. The outcome of interest in this review is retinal ganglion cell density and apoptosis for animal studies and retinal nerve fiber layer thickness for human studies.

RESULTS

The systematic search identified 591 studies of which 24 met the eligibility criteria, including 21 animal studies and three human studies. Only a few of the studies evaluated the same treatments, showing how diverse neuroprotector treatments are currently being evaluated as NAION treatment. From 21 animal studies, 14 studies showed significantly higher retinal ganglion cell density (1.49- to 2.81-fold) with neuroprotective treatment compared to control group. Two of three human studies in this review had also found a beneficial effect of preserving retinal nerve fiber layer thickness in NAION patients.

CONCLUSIONS

This review suggests the potential of neuroprotection as a viable option in the quest for an effective treatment strategy for NAION. Further studies, particularly clinical studies, are necessary to establish its efficacy in NAION patients.

Melatonin protects against NMDA-induced retinal ganglion cell injury by regulating the microglia-TNFα-RGC p38 MAPK pathway

Glaucoma, one of the most common ocular neurodegenerative diseases worldwide, is characterized by retinal ganglion cell (RGC) loss. There is a large body of literature that describes the neuroprotective role of melatonin against neurodegenerative diseases by regulating neuroinflammation, although the exact mechanism through which melatonin acts on RGC is still uncertain. This study assessed the protective effects of melatonin using a NMDA-induced RGC injury model, and studied the possible mechanisms involved in this process. Melatonin promoted RGC survival, improved retinal function, and inhibited the apoptosis and necrosis of retinal cells. To understand the mechanism of the neuroprotective effects of melatonin on RGC, microglia and inflammation-related pathways were assessed after melatonin administration and microglia ablation. Melatonin promoted RGC survival by suppressing microglia-derived proinflammatory cytokines, in particular TNFα, which in turn inhibited the activation of p38 MAPK pathway. Inhibiting TNFα or manipulating p38 MAPK pathway protected damaged RGC. Our results suggest that melatonin protects against NMDA-induced RGC injury by inhibiting the microglial TNFα-RGC p38 MAPK pathway. It should be considered a candidate neuroprotective therapy against retinal neurodegenerative diseases.

Natural products: protective effects against ischemia-induced retinal injury

Ischemic retinal damage, a common condition associated with retinal vascular occlusion, glaucoma, diabetic retinopathy, and other eye diseases, threatens the vision of millions of people worldwide. It triggers excessive inflammation, oxidative stress, apoptosis, and vascular dysfunction, leading to the loss and death of retinal ganglion cells. Unfortunately, minority drugs are available for treating retinal ischemic injury diseases, and their safety are limited. Therefore, there is an urgent need to develop more effective treatments for ischemic retinal damage. Natural compounds have been reported to have antioxidant, anti-inflammatory, and antiapoptotic properties that can be used to treat ischemic retinal damage. In addition, many natural compounds have been shown to exhibit biological functions and pharmacological properties relevant to the treatment of cellular and tissue damage. This article reviews the neuroprotective mechanisms of natural compounds involve treating ischemic retinal injury. These natural compounds may serve as treatments for ischemia-induced retinal diseases.

Biological Potential, Gastrointestinal Digestion, Absorption, and Bioavailability of Algae-Derived Compounds with Neuroprotective Activity: A Comprehensive Review

Currently, there is no known cure for neurodegenerative disease. However, the available therapies aim to manage some of the symptoms of the disease. Human neurodegenerative diseases are a heterogeneous group of illnesses characterized by progressive loss of neuronal cells and nervous system dysfunction related to several mechanisms such as protein aggregation, neuroinflammation, oxidative stress, and neurotransmission dysfunction. Neuroprotective compounds are essential in the prevention and management of neurodegenerative diseases. This review will focus on the neurodegeneration mechanisms and the compounds (proteins, polyunsaturated fatty acids (PUFAs), polysaccharides, carotenoids, phycobiliproteins, phenolic compounds, among others) present in seaweeds that have shown in vivo and in vitro neuroprotective activity. Additionally, it will cover the recent findings on the neuroprotective effects of bioactive compounds from macroalgae, with a focus on their biological potential and possible mechanism of action, including microbiota modulation. Furthermore, gastrointestinal digestion, absorption, and bioavailability will be discussed. Moreover, the clinical trials using seaweed-based drugs or extracts to treat neurodegenerative disorders will be presented, showing the real potential and limitations that a specific metabolite or extract may have as a new therapeutic agent considering the recent approval of a seaweed-based drug to treat Alzheimer’s disease.

Photoprotective Mechanism of Fucoxanthin in Ultraviolet B Irradiation-Induced Retinal Müller Cells Based on Lipidomics Analysis

Long-term exposure to sunlight and/or blue light causes vision damage to people of all ages. Dietary pigments and polyphenols have been shown to have photoprotective potential for eyes; however, many unknowns regarding the protective mechanism remain. In this study, we used ultraviolet B (UVB) irradiation-induced retinal Müller cells (RMCs) to screen for dietary polyphenols and pigment compounds with effective photoprotective activity. Fucoxanthin (FX) was shown to have the best therapeutic effect, and the mechanism was evaluated via lipidomics analysis. Both intra- and extracellular ROS, mitochondrial depolarization, and DNA damage induced by UVB irradiation were inhibited by FX. Meanwhile, FX modulated the MAPK signaling pathway, which is correlated with apoptosis and inflammation. Our lipidomics data revealed that FX regulated lipid metabolism disorder and protected the membrane structure. These results confirm the effective photoprotective effects of FX, which may lead to new insights into FX-functionalized photoprotective foods.

Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions

Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage. Secondary damage presents the greatest challenge for medical staff; however, there are currently few effective therapeutic targets for secondary damage. Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system. Homer signaling can exert either positive or negative effects during such insults, depending on the specific subtype of Homer protein. Homer 1b/c couples with other proteins to form postsynaptic densities, which form the basis of synaptic transmission, while Homer1a expression can be induced by harmful external factors. Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells, mediated or affected by extracellular or intracellular signaling or cytoskeletal processes. This review summarizes the structural features, related signaling pathways, and diverse roles of Homer proteins in physiological and pathological processes. Upregulating Homer1a or downregulating Homer1b/c may play a neuroprotective role in secondary brain injuries. Homer also plays an important role in the formation of photoreceptor synapses. These findings confirm the neuroprotective effects of Homer, and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.

Intravitreal Injection of Long-Acting Pegylated Granulocyte Colony-Stimulating Factor Provides Neuroprotective Effects via Antioxidant Response in a Rat Model of Traumatic Optic Neuropathy

Traumatic optic neuropathy (TON) may cause severe visual loss following direct or indirect head trauma which may result in optic nerve injuries and therefore contribute to the subsequent loss of retinal ganglion cells by inflammatory mediators and reactive oxygen species (ROS). Granulocyte colony-stimulating factor (G-CSF) provides the anti-inflammatory and anti-oxidative actions but has a short half-life and also induces leukocytosis upon typical systemic administration. The purpose of the present study was to investigate the relationship between the anti-oxidative response and neuroprotective effects of long-acting pegylated human G-CSF (PEG-G-CSF) in a rat model of optic nerve crush (ONC). Adult male Wistar rats (150-180 g) were chosen to have a sham operation in one eye and have ONC in the other. PEG-G-CSF or phosphate-buffered saline (PBS control) was immediately administered after ONC by intravitreal injection (IVI). We found the IVI of PEG-G-CSF does not induce systemic leukocytosis, but increases survival of RGCs and preserves the visual function after ONC. TUNEL assays showed fewer apoptotic cells in the retina in the PEG-G-CSF-treated eyes. The number of sorely ED1-positive cells was attenuated at the lesion site in the PEG-G-CSF-treated eyes. Immunoblotting showed up-regulation of p-Akt1, Nrf2, Sirt3, and HO-1 in the ON of the PEG-G-CSF-treated eyes. Our results demonstrated that one IVI of long-acting PEG-G-CSF is neuroprotective in the rONC. PEG-G-CSF activates the p-Akt1/Nrf2/Sirt3 and the p-Akt1/Nrf2/HO-1 axes to provide the antioxidative action and further attenuated RGC apoptosis and neuroinflammation. This provides crucial preclinical information for the development of alternative therapy with IVI of PEG-G-CSF in TON.

Diterpene Ginkgolides Meglumine Injection inhibits apoptosis induced by optic nerve crush injury via modulating MAPKs signaling pathways in retinal ganglion cells

ETHNOPHARMACOLOGICAL RELEVANCE

Diterpene Ginkgolides Meglumine Injection (DGMI) is made of extracts from Ginkgo biloba L, including Ginkgolides A, B, and K and some other contents, and has been widely used as the treatment of cerebral ischemic stroke in clinic. It can be learned from the "Compendium of Materia Medica" that Ginkgo possesses the effect of "dispersing toxin". The ancient Chinese phrase "dispersing toxin" is now explained as elimination of inflammation and oxidative state in human body. And it led to the original ideas for today's anti-oxidation studies of Ginkgo in apoptosis induced by optic nerve crush injury.

AIM OF THE STUDY

To investigate the underlying molecular mechanism of the DGMI in retinal ganglion cells (RGCs) apoptosis.

MATERIALS AND METHODS

TUNEL staining was used to observe the anti-apoptotic effects of DGMI on the adult rat optic nerve injury (ONC) model, and flow cytometry and hoechst 33,342 staining were used to observe the anti-apoptotic effects of DGMI on the oxygen glucose deprivation (OGD) induced RGC-5 cells injury model. The regulation of apoptosis and MAPKs pathways were investigated with Immunohistochemistry and Western blotting.

RESULTS

This study demonstrated that DGMI is able to decrease the conduction time of F-VEP and ameliorate histological features induced by optic nerve crush injury in rats. Immunohistochemistry and TUNEL staining results indicated that DGMI can also inhibit cell apoptosis via modulating MAPKs signaling pathways. In addition, treatment with DGMI markedly improved the morphological structures and decreased the apoptotic index in RGC-5 cells. Mechanistically, DGMI could significantly inhibit cell apoptosis by inhibiting p38, JNK and Erk1/2 activation.

CONCLUSION

The study shows that DGMI and ginkgolides inhibit RGCs apoptosis by impeding the activation of MAPKs signaling pathways in vivo and in vitro. Therefore, the present study provided scientific evidence for the underlying mechanism of DGMI and ginkgolides on optic nerve crush injury.

Modulation of vigabatrin induced cerebellar injury: the role of caspase-3 and RIPK1/RIPK3-regulated cell death pathways

Vigabatrin is the drug of choice in resistant epilepsy and infantile spasms. Ataxia, tremors, and abnormal gait have been frequently reported following its use indicating cerebellar involvement. This study aimed, for the first time, to investigate the involvement of necroptosis and apoptosis in the VG-induced cerebellar cell loss and the possible protective role of combined omega-3 and vitamin B12 supplementation. Fifty Sprague-Dawley adult male rats (160-200 g) were divided into equal five groups: the control group received normal saline, VG200 and VG400 groups received VG (200 mg or 400 mg/kg, respectively), VG200 + OB and VG400 + OB groups received combined VG (200 mg or 400 mg/kg, respectively), vitamin B12 (1 mg/kg), and omega-3 (1 g/kg). All medications were given daily by gavage for four weeks. Histopathological changes were examined in H&E and luxol fast blue (LFB) stained sections. Immunohistochemical staining for caspase-3 and receptor-interacting serine/threonine-protein kinase-1 (RIPK1) as well as quantitative real-time polymerase chain reaction (qRT-PCR) for myelin basic protein (MBP), caspase-3, and receptor-interacting serine/threonine-protein kinase-3 (RIPK3) genes were performed. VG caused a decrease in the granular layer thickness and Purkinje cell number, vacuolations, demyelination, suppression of MBP gene expression, and induction of caspases-3, RIPK1, and RIPK3 in a dose-related manner. Combined supplementation with B12 and omega-3 improved the cerebellar histology, increased MBP, and decreased apoptotic and necroptotic markers. In conclusion, VG-induced neuronal cell loss is dose-dependent and related to both apoptosis and necroptosis. This could either be ameliorated (in low-dose VG) or reduced (in high-dose VG) by combined supplementation with B12 and omega-3.

The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms

We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.

The Benefits and Hazards of Intravitreal Mesenchymal Stem Cell (MSC) Based-Therapies in the Experimental Ischemic Optic Neuropathy

Mesenchymal stem cell (MSC) therapy has been investigated intensively for many years. However, there is a potential risk related to MSC applications in various cell niches. Methods: The safety of intravitreal MSC application and the efficacy of MSC-derived conditioned medium (MDCM) were evaluated in the normal eye and the diseased eye, respectively. For safety evaluation, the fundus morphology, visual function, retinal function, and histological changes of the retina were examined. For efficacy evaluation, the MDCM was intravitreally administrated in a rodent model of anterior ischemic optic neuropathy (rAION). The visual function, retinal ganglion cell (RGC) density, and neuroinflammation were evaluated at day 28 post-optic nerve (ON) infarct. Results: The fundus imaging showed that MSC transplantation induced retinal distortion and venous congestion. The visual function, retinal function, and RGC density were significantly decreased in MSC-treated eyes. MSC transplantation induced astrogliosis, microgliosis, and macrophage infiltration in the retina due to an increase in the HLA-DR-positive MSC proportion in vitreous. Treatment with the MDCM preserved the visual function and RGC density in rAION via inhibition of macrophage infiltration and RGC apoptosis. Conclusions: The vitreous induced the HLA-DR expression in the MSCs to cause retinal inflammation and retina injury. However, the MDCM provided the neuroprotective effects in rAION.