Oxidative Stress-Induced Pentraxin 3 Expression Human Retinal Pigment Epithelial Cells is Involved in the Pathogenesis of Age-Related Macular Degeneration

Alzheimer's disease and age-related macular degeneration: Shared and distinct immune mechanisms

Alzheimer's disease (AD) and age-related macular degeneration (AMD) represent the leading causes of dementia and vision impairment in the elderly, respectively. The retina is an extension of the brain, yet these two central nervous system (CNS) compartments are often studied separately. Despite affecting cognition vs. vision, AD and AMD share neuroinflammatory pathways. By comparing these diseases, we can identify converging immune mechanisms and potential cross-applicable therapies. Here, we review immune mechanisms highlighting the shared and distinct aspects of these two age-related neurodegenerative conditions, focusing on responses to hallmark disease manifestations, the opposite role of overlapping immune risk loci, and potential unified therapeutic approaches. We also discuss unique tissue requirements that may dictate different outcomes of conserved immune mechanisms and how we can reciprocally utilize lessons from AD therapeutics to AMD. Looking forward, we suggest promising directions for research, including the exploration of regenerative medicine, gene therapies, and innovative diagnostics.

Pentraxin3 exacerbates acute pancreatitis injury by inhibiting oxidative phosphorylation pathway

Local pancreatic necrosis and systemic inflammatory response caused by acute pancreatitis (AP) are closely related to the disease prognosis and severity. This study aimed to explore whether pentraxin 3 (PTX3) regulates AP pancreatic necrosis and reveals the underlying mechanism. By using AP time gradient transcriptomics, proteomics and liquid phase chip analysis, we found a close association between PTX3 and AP. Subsequently, caerulein (CAE) induced in vivo AP model and CCK induced in vitro acinar cell damage model were constructed to determine the expression of PTX3 and its regulation of AP. The results showed that PTX3 was highly expressed in the CAE-induced AP model. And more severe pancreatic tissue damage and increased serum amylase were observed after the intervention of recombinant protein PTX3, which was strongly linked to the decreasing in mitochondrial membrane potential, increasing in reactive oxygen species, and regulation by oxidative phosphorylation pathway. PTX3 could exacerbate acinar cell damage in AP by mediating the process of oxidative phosphorylation.

Inter-tissue differences in oxidative stress susceptibility reveal a less stable endothelial barrier in the brain than in the retina

Oxidative stress can impair the endothelial barrier and thereby enable autoantibody migration in Neuromyelitis optica spectrum disorder (NMOSD). Tissue-specific vulnerability to autoantibody-mediated damage could be explained by a differential, tissue-dependent endothelial susceptibility to oxidative stress. In this study, we aim to investigate the barrier integrity and complement profiles of brain and retinal endothelial cells under oxygen-induced oxidative stress to address the question of whether the pathomechanism of NMOSD preferentially affects the brain or the retina. Primary human brain microvascular endothelial cells (HBMEC) and primary human retinal endothelial cells (HREC) were cultivated at different cell densities (2.5*104 to 2*105 cells/cm2) for real-time cell analysis. Both cell types were exposed to 100, 500 and 2500 μM H2O2. Immunostaining (CD31, VE-cadherin, ZO-1) and Western blot, as well as complement protein secretion using multiplex ELISA were performed. HBMEC and HREC cell growth phases were cell type-specific. While HBMEC cell growth could be categorized into an initial peak, proliferation phase, plateau phase, and barrier breakdown phase, HREC showed no proliferation phase, but entered the plateau phase immediately after an initial peak. The plateau phase was 7 h shorter in HREC. Both cell types displayed a short-term, dose-dependent adaptive response to H2O2. Remarkably, at 100 μM H2O2, the transcellular resistance of HBMEC exceeded that of untreated cells. 500 μM H2O2 exerted a more disruptive effect on the HBMEC transcellular resistance than on HREC. Both cell types secreted complement factors H (FH) and I (FI), with FH secretion remaining stable after 2 h, but FI secretion decreasing at higher H2O2 concentrations. The observed differences in resistance to oxidative stress between primary brain and retinal endothelial cells may have implications for further studies of NMOSD and other autoimmune diseases affecting the eye and brain. These findings may open novel perspectives for the understanding and treatment of such diseases.

The toxic effects of polystyrene microplastic/nanoplastic particles on retinal pigment epithelial cells and retinal tissue

The increasing use of contact lenses, artificial tears, and anti-vascular endothelial growth factor (anti-VEGF) drug injections for age-related macular degeneration has heightened the likelihood of eye exposure to microplastic particles. Extensive research has established that microplastic particles can induce oxidative stress on the ocular surface, resulting in damage. However, the impact of these particles on the retina remains unclear. Therefore, this study investigated whether microplastics/nanoplastics (MPs/NPs) cause retinal damage. In vitro human retinal pigment epithelial (RPE) cells were exposed to polystyrene MPs and NPs for 48 h. Assessment of cell viability using WST-8; evaluation of TNF-α and IL-1β expression; observation of cell morphology and particle invasion via TEM; measurement of ROS levels using the DCFDA reagent; and western blot analysis of SOD2, FIS1, Drp1, and LC3B expression were conducted. In vivo experiments involved intravitreal injection of MPs/NPs in rats, followed by retinal H&E staining 24 h later and evaluation of TNF-α and IL-1β expression. Results indicated that exposure to MPs did not significantly alter RPE cell viability, whereas exposure to NPs led to a noticeable decrease. TEM images revealed NPs' penetration into cells, causing increased oxidative stress (SOD2), mitochondrial fission (FIS1, Drp1), and mitochondrial autophagy (LC3B). In vivo experiments demonstrated an increase in inflammatory cells in retinal tissues exposed to NPs, along with elevated levels of TNF-α and IL-1β. Conclusively, both MPs and NPs impact the retina, with NPs displaying greater toxicity. NPs significantly elevate ROS levels in the retina and induce mitochondrial fission and mitophagy in RPE cells compared to MPs.

The role of pentraxin 3 and oxidative status in the prognosis of multiple myeloma

Multiple myeloma (MM) is a bone marrow malignancy characterized by plasma cell proliferation. It was aimed to investigate pentraxin 3 (PTX3) levels, oxidative/antioxidative status, and their correlation in MM. In the study, four groups were established, including newly diagnosed MM (NDMM), MM in remission (Rem-MM), relapsed/refractory MM (RRMM) patients, and a healthy control group. PTX3 levels were measured using enzyme-linked immunosorbent assay, and the total antioxidant status (TAS) and total oxidant status (TOS) were assessed with an autoanalyzer. The oxidative stress index (OSI) was calculated using the formula: OSI (arbitrary unit) = TOS (µmol H2O2 Eq/L)/TAS (mmol Trolox Eq/L) × 100. The study involved comparing PTX3, TAS, TOS, and OSI levels among these four groups. PTX3 levels were significantly elevated in NDMM and RRMM groups compared to controls and the Rem-MM group (NDMM vs control; p < 0.001, NDMM vs Rem-MM; p < 0.001, RRMM vs control; p < 0.001, and RRMM vs Rem-MM; p = 0.006). TAS was higher in NDMM and RRMM groups versus controls (p = 0.009 and p < 0.001, respectively), and TOS was higher in rem-MM group versus NDMM and control groups (p < 0.001 and p = 0.016, respectively). OSI was higher in the Rem-MM group than in NDMM and RRMM groups (p < 0.001 and p = 0.009, respectively). Multivariate analysis confirmed associations between MM groups and PTX3 levels. Receiver operating characteristic analysis revealed high specificity (90%) and sensitivity (79%) for PTX3 in NDMM at a >0.56 ng/mL cut-off value. This study suggests that PTX3 levels may have diagnostic and prognostic potential in MM and its relationship with oxidative stress requires further exploration.

Choroidal Mast Cells and Pathophysiology of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of vision loss in elderly patients. Its etiology and progression are, however, deeply intertwined with various cellular and molecular interactions within the retina and choroid. Among the key cellular players least studied are choroidal mast cells, with important roles in immune and allergic responses. Here, we will review what is known regarding the pathophysiology of AMD and expand on the recently proposed intricate roles of choroidal mast cells and their activation in outer retinal degeneration and AMD pathogenesis. We will focus on choroidal mast cell activation, the release of their bioactive mediators, and potential impact on ocular oxidative stress, inflammation, and overall retinal and choroidal health. We propose an important role for thrombospondin-1 (TSP1), a major ocular angioinflammatory factor, in regulation of choroidal mast cell homeostasis and activation in AMD pathogenesis. Drawing from limited studies, this review underscores the need for further comprehensive studies aimed at understanding the precise roles changes in TSP1 levels and choroidal mast cell activity play in pathophysiology of AMD. We will also propose potential therapeutic strategies targeting these regulatory pathways, and highlighting the promise they hold for curbing AMD progression through modulation of mast cell activity. In conclusion, the evolving understanding of the role of choroidal mast cells in AMD pathogenesis will not only offer deeper insights into the underlying mechanisms but will also offer opportunities for development of novel preventive strategies.

Multi-Wavelength Photobiomodulation Ameliorates Sodium Iodate-Induced Age-Related Macular Degeneration in Rats

Age-related macular degeneration (AMD) is a global health challenge. AMD causes visual impairment and blindness, particularly in older individuals. This multifaceted disease progresses through various stages, from asymptomatic dry to advanced wet AMD, driven by various factors including inflammation and oxidative stress. Current treatments are effective mainly for wet AMD; the therapeutic options for dry AMD are limited. Photobiomodulation (PBM) using low-energy light in the red-to-near-infrared range is a promising treatment for retinal diseases. This study investigated the effects of multi-wavelength PBM (680, 780, and 830 nm) on sodium iodate-induced oxidatively damaged retinal tissue. In an in vivo rat model of AMD induced by sodium iodate, multi-wavelength PBM effectively protected the retinal layers, reduced retinal apoptosis, and prevented rod bipolar cell depletion. Furthermore, PBM inhibited photoreceptor degeneration and reduced retinal pigment epithelium toxicity. These results suggest that multi-wavelength PBM may be a useful therapeutic strategy for AMD, mitigating oxidative stress, preserving retinal integrity, and preventing apoptosis.

Construction of an Exudative Age-Related Macular Degeneration Diagnostic and Therapeutic Molecular Network Using Multi-Layer Network Analysis, a Fuzzy Logic Model, and Deep Learning Techniques: Are Retinal and Brain Neurodegenerative Disorders Related?

Neovascular age-related macular degeneration (nAMD) is a leading cause of irreversible visual impairment in the elderly. The current management of nAMD is limited and involves regular intravitreal administration of anti-vascular endothelial growth factor (anti-VEGF). However, the effectiveness of these treatments is limited by overlapping and compensatory pathways leading to unresponsiveness to anti-VEGF treatments in a significant portion of nAMD patients. Therefore, a system view of pathways involved in pathophysiology of nAMD will have significant clinical value. The aim of this study was to identify proteins, miRNAs, long non-coding RNAs (lncRNAs), various metabolites, and single-nucleotide polymorphisms (SNPs) with a significant role in the pathogenesis of nAMD. To accomplish this goal, we conducted a multi-layer network analysis, which identified 30 key genes, six miRNAs, and four lncRNAs. We also found three key metabolites that are common with AMD, Alzheimer's disease (AD) and schizophrenia. Moreover, we identified nine key SNPs and their related genes that are common among AMD, AD, schizophrenia, multiple sclerosis (MS), and Parkinson's disease (PD). Thus, our findings suggest that there exists a connection between nAMD and the aforementioned neurodegenerative disorders. In addition, our study also demonstrates the effectiveness of using artificial intelligence, specifically the LSTM network, a fuzzy logic model, and genetic algorithms, to identify important metabolites in complex metabolic pathways to open new avenues for the design and/or repurposing of drugs for nAMD treatment.

Combination of Lactobacillus fermentum NS9 and aronia anthocyanidin extract alleviates sodium iodate-induced retina degeneration

It is important to explore the effective approaches to prevent dry age-related macular degeneration (AMD). In this study, significantly decreased full-field electroretinograms wave amplitudes and disordered retina structures were detected in rat retinas of sodium iodate induced dry AMD model. Six a- and b-wave amplitudes and the antioxidant activities were significantly increased, and the outer nuclear layer thickness was significantly improved in the rat retinas treated with the combination of Lactobacillus fermentum NS9 (LF) and aronia anthocyanidin extract (AAE) compared with the model. The effects were much better than the treatment with AAE alone. The proteomics analysis showed the expressions of α-, β- and γ-crystallins were increased by 3-8 folds in AAE treated alone and by 6-11 folds in AAE + LF treatment compared with the model, which was further confirmed by immuno-blotting analysis. Analysis of gut microbial composition indicated that higher abundance of the genus Parasutterella and species P. excrementihominis was found in the AAE + LF treatment compared with the other groups. The results indicated that the combined treatment of AAE + LF is a potential way to prevent the retina degeneration which is significantly better than the AAE treated alone.

Targeting Mitochondria as a Therapeutic Approach for Parkinson's Disease

Neurodegeneration is among the most critical challenges that involve modern societies and annually influences millions of patients worldwide. While the pathophysiology of Parkinson's disease (PD) is complicated, the role of mitochondrial is demonstrated. The in vitro and in vivo models and genome-wide association studies in human cases proved that specific genes, including PINK1, Parkin, DJ-1, SNCA, and LRRK2, linked mitochondrial dysfunction with PD. Also, mitochondrial DNA (mtDNA) plays an essential role in the pathophysiology of PD. Targeting mitochondria as a therapeutic approach to inhibit or slow down PD formation and progression seems to be an exciting issue. The current review summarized known mutations associated with both mitochondrial dysfunction and PD. The significance of mtDNA in Parkinson's disease pathogenesis and potential PD therapeutic approaches targeting mitochondrial dysfunction was then discussed.

Mini-αA Upregulates the miR-155-5p Target Gene CDK2 and Plays an Antiapoptotic Role in Retinal Pigment Epithelial Cells during Oxidative Stress

Background

Age-related macular degeneration (AMD) is the leading cause of serious vision loss in the elderly. Regulating microRNA (miRNA) gene expression offers exciting new avenues for treating AMD. This study aimed to investigate whether miRNAs and their target genes play an antiapoptotic role during oxidative stress-induced apoptosis of retinal pigment epithelial (RPE) cells via mini-αA.

Methods

ARPE-19 cells were treated with 3.5 mM NaIO3 for 48 h to establish a retinal degeneration model. Cells were treated with mini-αA (10, 15, and 20 μM) for 4 h. miR-155-5p was knocked down and overexpressed. Cell viability and apoptosis were measured using the Cell Counting Kit-8 assay and flow cytometry, respectively. The reactive oxygen species level was detected by flow cytometry. miR-155-5p target genes were predicted via bioinformatics. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed for miR-155-5p target genes. A quantitative real-time polymerase chain reaction was performed to detect miRNAs and cell cycle-related target genes. Western blotting was performed to measure the levels of apoptotic pathway genes encoding Bcl-2, Bax, cleaved caspase-3, and cyclin-dependent kinase 2 (CDK2). Dual-luciferase reporter gene assay was performed to verify the targeted binding relationship between miR-155-5p and CDK2.

Results

NaIO3 can induce oxidative damage and promote apoptosis. Conversely, mini-αA had inhibitory effects and could reverse the oxidative damage and apoptosis triggered by NaIO3 in the retinal degeneration model. The expression of miR-155-5p was upregulated in cells treated with NaIO3 and was downregulated after mini-αA treatment. Furthermore, miR-155-5p can target the following cell cycle-related and proliferation-related genes: CDK2, CDK4, CCND1, and CCND2. Moreover, our study indicated that miR-155-5p was involved in the antioxidative damage and antiapoptotic effects of mini-αA via CDK2 regulation.

Conclusions

miR-155-5p promotes the antioxidative damage and antiapoptotic effects of mini-αA during oxidative stress-induced apoptosis of RPE cells via CDK2 regulation. This study provides a new therapeutic target for AMD.

NLRX1 increases human retinal pigment epithelial autophagy and reduces H2O2-induced oxidative stress and inflammation by suppressing FUNDC1 phosphorylation and NLRP3 activation

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of impaired vision as well as some earlier effects, such as reading and face recognition. Oxidative damage and inflammation of retinal pigment epithelial (RPE) cells are major causes of AMD. Additionally, autophagy in RPE cells can lead to cellular homeostasis under oxidative stress. Nucleotide-binding oligomerization domain (NOD)-like receptor X1 (NLRX1) is a mysterious modulator of the immune system function which inhibits inflammatory response, attenuates reactive oxygen species (ROS) production, and regulates autophagy. This study attempted to explore the role of NLRX1 in oxidative stress, inflammation, and autophagy in AMD.

METHODS

An in vitro model of AMD was built in human retinal pigment epithelial cell line 19 (ARPE-19) treated with H₂O₂. The cell viability, NLRX1 expressions, levels of superoxide dismutase (SOD), glutathione (GHS), and ROS, concentrations of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and monocyte chemoattractant protein-1 (MCP-1), expressions of NLRX1, p62, LC3-II/LC3-I, FUNDC1, and NOD-like receptor protein 3 (NLRP3) inflammasome were expounded by cell counting kit-8, colorimetric, enzyme-linked immunosorbent serologic assay (ELISA), and Western blot assay.

RESULTS

H₂O₂ treatment notably reduced the relative protein expression of NLRX1. Meanwhile, H₂O₂ incubation decreased cell viability, diminished SOD and GSH concentrations, accompanied with the increased level of ROS, enhanced IL-1β, TNF-α, IL-6, and MCP-1 concentrations, and aggrandized the relative protein expression of p62 with reduced LC3-II/LC3-I ratio. Moreover, these results were further promoted with knockdown of NLRX1 and reversed with overexpression. Mechanically, silencing of NLRX1 further observably enhanced the relative levels of -phosphorylated FUNDC1/FUNDC1, and NLRP3 inflammasome-related proteins, while overexpression of NLRX1 exhibited inverse results in the H₂O₂-induced ARPE-19 cells.

CONCLUSION

NLRX1 suppressed H₂O₂-induced oxidative stress and inflammation, and facilitated autophagy by suppressing FUNDC1 phosphorylation and NLRP3 activation in ARPE-19 cells.

Protrusion of KCNJ13 Gene Knockout Retinal Pigment Epithelium Due to Oxidative Stress–Induced Cell Death

Purpose

This study was performed to elucidate the mechanisms of morphological abnormalities in a Leber congenital amaurosis 16 (LCA16) cell model using KCNJ13 knockout (KO) retinal pigment epithelial cells derived from human iPS cells (hiPSC-RPE).

Methods

In KCNJ13 KO and wild-type hiPSC-RPE cells, ZO-1 immunofluorescence was performed, and confocal images were captured. The area and perimeter of each cell were measured. To detect cell death, ethidium homodimer III (EthD-III) staining and LDH assay were used. Scanning electron microscopy (SEM) was used to observe the cell surface. The expression levels of oxidative stress-related genes were examined by quantitative PCR. To explore the effects of oxidative stress, tert-butyl hydroperoxide (t-BHP) was administered to the hiPSC-RPE cells. Cell viability was tested by MTS assay, whereas oxidative damage was monitored by oxidized (GSSG) and reduced glutathione levels.

Results

The area and perimeter of KCNJ13-KO hiPSC-RPE cells were enlarged. EthD-III-positive cells were increased with more dead cells in the protruded region. The KO RPE had significantly higher LDH levels in the medium. SEM observations revealed aggregated cells having broken cell surfaces on the KO RPE sheet. The KCNJ13-deficient RPE showed increased expression levels of oxidative stress-related genes and total glutathione levels. Furthermore, t-BHP induced a significant increase in cell death and GSSG levels in the KO RPE.

Conclusions

We suggest that in the absence of the Kir.7.1 potassium channel, human RPE cells are vulnerable to oxidative stress and ultimately die. The dying/dead cells form aggregates and protrude from the surviving KCNJ13-deficient RPE sheet.

The transcriptome profile of RPE cells by the fullerenol against hydrogen peroxide stress

Age-related macular degeneration (AMD) causes central vision impairment with increased incidence. In the pathogenesis of AMD, reactive oxygen species (ROS) are associated with RPE cell apoptosis. H₂O₂ is an oxidative toxicant and is used to establish the AMD in vitro model. However, the mechanisms of ROS in H₂O₂-induced AMD are still unclear. Fullerenol, a promising antioxidant of nanomaterials, protects RPE cells from ROS attack. In addition to working as a scavenger, little is known about the antioxidant mechanism of fullerenol in RPE cells. In this study, transcriptome sequencing was performed to examine the global changes in mRNA transcripts induced by H₂O₂ in human ARPE-19 cells. Moreover, we comprehensively investigated the protective effects of fullerenol against H₂O₂-induced oxidative injury by RNA sequencing. Gene Ontology enrichment analysis showed that those pathways related to the release of positive regulation of DNA-templated transcription and negative regulation of apoptotic process were affected. Finally, we found that 12 hub genes were related to the oxidative-protection function of fullerenol. In summary, H₂O₂ affected these hub genes and signaling pathways to regulate the senescence of RPE cells. Moreover, fullerenol is a potent nanomaterial that protects the RPE and would be a promising approach for AMD prevention.

The pathophysiological mechanisms underlying diabetic retinopathy

Diabetic retinopathy (DR) is the most common complication of diabetes mellitus (DM), which can lead to visual impairment and even blindness in severe cases. DR is generally considered to be a microvascular disease but its pathogenesis is still unclear. A large body of evidence shows that the development of DR is not determined by a single factor but rather by multiple related mechanisms that lead to different degrees of retinal damage in DR patients. Therefore, this article briefly reviews the pathophysiological changes in DR, and discusses the occurrence and development of DR resulting from different factors such as oxidative stress, inflammation, neovascularization, neurodegeneration, the neurovascular unit, and gut microbiota, to provide a theoretical reference for the development of new DR treatment strategies.

Pathophysiology of Age-Related Macular Degeneration: Implications for Treatment

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive retinal disease that affects millions of people worldwide and has become the leading cause of visual impairment in developed countries. The disease etiopathogenesis is not understood fully, although many triggers and processes that lead to dysfunction and degeneration of the retinal pigment epithelium (RPE) have already been identified. Thus, the lack of cellular control of oxidative stress, altered proteostasis, dysfunction of lipid homeostasis, and mitochondrial dysfunction form an internal feedback loop that causes the RPE to fail and allows accumulation of abnormal misfolded proteins and abnormal lipids that will form drusen. An inadequate antioxidant response, deficits in autophagy mechanisms, and dysregulation of the extracellular matrix (ECM) help to increase the deposition of abnormal drusen material over time. The drusen then act as inflammatory centers that trigger chronic inflammation of the subretinal space in which microglia and recruited macrophages are also involved, and where the complement system is a key component. Choriocapillaris degeneration and nutritional influences are also classic elements recognized in the AMD pathophysiology. The genetic component of the disease is embodied in the recognition of the described risk or protective polymorphisms of some complement and ECM related genes (mainly CFH and ARMS2/HTRA1). Thus, carriers of the risk haplotype at ARMS2/HTRA1 have a higher risk of developing late AMD at a younger age. Finally, gut microbiota and epigenetics may play a role in modulating the progression to advanced AMD with the presence of local inflammatory conditions. Because of multiple implicated processes, different complex combinations of treatments will probably be the best option to obtain the best visual results; they in turn will differ depending on the type and spectrum of disease affecting individual patients or the disease stage in each patient at a specific moment. This will undoubtedly lead to personalized medicine for control and hopefully find a future cure. This necessitates the continued unraveling of all the processes involved in the pathogenesis of AMD that must be understood to devise the combinations of treatments for different concurrent or subsequent problems.

Toll-Like Receptor Signalling Pathways and the Pathogenesis of Retinal Diseases

There is growing evidence that the pathogenesis of retinal diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD) have a significant chronic inflammatory component. A vital part of the inflammatory cascade is through the activation of pattern recognition receptors (PRR) such as toll-like receptors (TLR). Here, we reviewed the past and current literature to ascertain the cumulative knowledge regarding the effect of TLRs on the development and progression of retinal diseases. There is burgeoning research demonstrating the relationship between TLRs and risk of developing retinal diseases, utilising a range of relevant disease models and a few large clinical investigations. The literature confirms that TLRs are involved in the development and progression of retinal diseases such as DR, AMD, and ischaemic retinopathy. Genetic polymorphisms in TLRs appear to contribute to the risk of developing AMD and DR. However, there are some inconsistencies in the published reports which require further elucidation. The evidence regarding TLR associations in retinal dystrophies including retinitis pigmentosa is limited. Based on the current evidence relating to the role of TLRs, combining anti-VEGF therapies with TLR inhibition may provide a longer-lasting treatment in some retinal vascular diseases.

The Long Pentraxin PTX3 as a New Biomarker and Pharmacological Target in Age-Related Macular Degeneration and Diabetic Retinopathy

Age related macular degeneration (AMD) and diabetic retinopathy (DR) are multifactorial, neurodegenerative and inflammatory diseases of the eye primarily involving cellular and molecular components of the outer and inner blood-retina barriers (BRB), respectively. Largely contributed by genetic factors, particularly polymorphisms in complement genes, AMD is a paradigm of retinal immune dysregulation. DR, a major complication of diabetes mellitus, typically presents with increased vascular permeability and occlusion of the retinal vasculature that leads, in the proliferative form of the disease, to neovascularization, a pathogenic trait shared with advanced AMD. In spite of distinct etiology and clinical manifestations, both pathologies share common drivers, such as chronic inflammation, either of immune (in AMD) or metabolic (in DR) origin, which initiates and propagates degeneration of the neural retina, yet the underlying mechanisms are still unclear. As a soluble pattern recognition molecule with complement regulatory functions and a marker of vascular damage, long pentraxin 3 (PTX3) is emerging as a novel player in ocular homeostasis and a potential pharmacological target in neurodegenerative disorders of the retina. Physiologically present in the human eye and induced in inflammatory conditions, this protein is strategically positioned at the BRB interface, where it acts as a “molecular trap” for complement, and modulates inflammation both in homeostatic and pathological conditions. Here, we discuss current viewpoints on PTX3 and retinal diseases, with a focus on AMD and DR, the roles therein proposed for this pentraxin, and their implications for the development of new therapeutic strategies.

The Protective Effects of α-Mangostin Attenuate Sodium Iodate-Induced Cytotoxicity and Oxidative Injury via Mediating SIRT-3 Inactivation via the PI3K/AKT/PGC-1α Pathway

It is well known that age-related macular degeneration (AMD) is an irreversible neurodegenerative disease that can cause blindness in the elderly. Oxidative stress-induced retinal pigment epithelial (RPE) cell damage is a part of the pathogenesis of AMD. In this study, we evaluated the protective effect and mechanisms of alpha-mangostin (α-mangostin, α-MG) against NaIO3-induced reactive oxygen species (ROS)-dependent toxicity, which activates apoptosis in vivo and in vitro. MTT assay and flow cytometry demonstrated that the pretreatment of ARPE-19 cells with α-MG (0, 3.75, 7.5, and 15 μM) significantly increased cell viability and reduced apoptosis from NaIO3-induced oxidative stress in a concentration-dependent manner, which was achieved by the inhibition of Bax, cleaved PARP-1, cleaved caspase-3 protein expression, and enhancement of Bcl-2 protein. Furthermore, pre-incubation of ARPE-19 cells with α-MG markedly inhibited the intracellular ROS and extracellular H2O2 generation via blocking of the abnormal enzyme activities of superoxide dismutase (SOD), the downregulated levels of catalase (CAT), and the endogenous antioxidant, glutathione (GSH), which were regulated by decreasing PI3K-AKT-PGC-1α-STRT-3 signaling in ARPE-19 cells. In addition, our in vivo results indicated that α-MG improved retinal deformation and increased the thickness of both the outer nuclear layer and inner nuclear layer by inhibiting the expression of cleaved caspase-3 protein. Taken together, our results suggest that α-MG effectively protects human ARPE-19 cells from NaIO3-induced oxidative damage via antiapoptotic and antioxidant effects.

Assessing the protective effects of cryptotanshinone on CoCl2‑induced hypoxia in RPE cells

The development of several retinal diseases is closely related to hypoxia. As a component of the Traditional Chinese medicine Salvia miltiorrhiza, the effects of cryptotanshinone (CT) on retinal cells under hypoxic conditions are not well understood. The aim of the present study was to explore how CT exerted its protective effects on retinal pigment epithelium (RPE) cells under hypoxic conditions induced by cobalt chloride (CoCl₂). The effects of CT were investigated using a Cell Counting Kit-8 assay, Annexin V-FITC/PI staining, reverse transcription-quantitative PCR and western blotting in ARPE-19 cells. CT (10 and 20 µM) reduced the CoCl₂-induced increase in vascular endothelial growth factor expression and hypoxia-inducible transcription factor-1α expression in ARPE-19 cells. Additionally, CT alleviated hypoxia-induced apoptosis by regulating Bcl-2 and Bax protein expression. CT treatment also reduced the increase in the mRNA levels of IL-6, IL-1β and TNF-α induced by CoCl₂. In summary, CT may protect RPE cells against apoptosis and inflammation in CoCl₂-induced hypoxia, and these results warrant further in vivo study into its value as a drug for treating hypoxic eye diseases.

Sodium Iodate-Induced Degeneration Results in Local Complement Changes and Inflammatory Processes in Murine Retina

Age-related macular degeneration (AMD), one of the leading causes of blindness worldwide, causes personal suffering and high socioeconomic costs. While there has been progress in the treatments for the neovascular form of AMD, no therapy is yet available for the more common dry form, also known as geographic atrophy. We analysed the retinal tissue in a mouse model of retinal degeneration caused by sodium iodate (NaIO3)-induced retinal pigment epithelium (RPE) atrophy to understand the underlying pathology. RNA sequencing (RNA-seq), qRT-PCR, Western blot, immunohistochemistry of the retinas and multiplex ELISA of the mouse serum were applied to find the pathways involved in the degeneration. NaIO3 caused patchy RPE loss and thinning of the photoreceptor layer. This was accompanied by the increased retinal expression of complement components c1s, c3, c4, cfb and cfh. C1s, C3, CFH and CFB were complement proteins, with enhanced deposition at day 3. C4 was upregulated in retinal degeneration at day 10. Consistently, the transcript levels of proinflammatory ccl-2, -3, -5, il-1β, il-33 and tgf-β were increased in the retinas of NaIO3 mice, but vegf-a mRNA was reduced. Macrophages, microglia and gliotic Müller cells could be a cellular source for local retinal inflammatory changes in the NaIO3 retina. Systemic complement and cytokines/chemokines remained unaltered in this model of NaIO3-dependent retinal degeneration. In conclusion, systemically administered NaIO3 promotes degenerative and inflammatory processes in the retina, which can mimic the hallmarks of geographic atrophy.

Electrophysiologic and Morphologic Strain Differences in a Low-Dose NaIO3-Induced Retinal Pigment Epithelium Damage Model

Purpose

We aimed to explore differences in the NaIO₃-elicited responses of retinal pigment epithelium (RPE) and other retinal cells associated with mouse strains and dosing regimens.

Methods

One dose of NaIO₃ at 10 or 15 mg/kg was given intravenously to adult male C57BL/6J and 129/SV-E mice. Control animals were injected with PBS. Morphologic and functional changes were characterized by spectral domain optical coherence tomography, electroretinography, histologic, and immunofluorescence techniques.

Results

Injection with 10 mg/kg of NaIO₃ did not cause consistent RPE or retinal changes in either strain. Administration of 15 mg/kg of NaIO₃ initially induced a large transient increase in scotopic electroretinography a-, b-, and c-wave amplitudes within 12 hours of injection, followed by progressive structural and functional degradation at 3 days after injection in C57BL/6J mice and at 1 week after injection in 129/SV-E mice. RPE cell loss occurred in a large posterior-central lesion with a ring-like transition zone of abnormally shaped cells starting 12 hours after NaIO₃ treatment.

Conclusions

NaIO₃ effects depended on the timing, dosage, and mouse strain. The RPE in the periphery was spared from damage compared with the central RPE. The large transient increase in the electroretinography was remarkable.

Translational Relevance

This study is a phase T1 translational research study focusing on the development and validation of a mouse model of RPE damage. It provides a detailed foundation for future research, informing choices of mouse strain, dosage, and time points to establish NaIO₃-induced RPE damage.

Malvidin and its derivatives exhibit antioxidant properties by inhibiting MAPK signaling pathways to reduce endoplasmic reticulum stress in ARPE-19 cells

Malvidin (MV) and its derivatives, such as malvidin-3-O-guaiacol (Mv3C) and malvidin-3-O-6-(acrylic acid-(2-hydroxy,4-carboxy-cyclohexanol)ester)-guaiacol (Mv3ACEC), are natural compounds with antioxidant properties. However, the basic mechanisms underlying their functional activities are unclear. In this study, we show that MV, Mv3C, and Mv3ACEC inhibit reactive oxygen species production and malondialdehyde content, promote glutathione peroxidase activity, and increase superoxide dismutase levels in ARPE-19 cells treated with H₂O₂. Western blotting and immunofluorescence analysis revealed that MV, Mv3C, and Mv3ACEC regulate mitogen-activated protein kinase signal transduction pathways related to endoplasmic reticulum stress. Interestingly, Mv3C and Mv3ACEC showed greater beneficial properties than MV. Our results show that MV and its derivatives have potential as therapeutic compounds for ocular diseases associated with oxidative stress, such as age-related macular degeneration.

SS-31 protect retinal pigment epithelial cells from H2 O2 -induced cell injury by reducing apoptosis

Evidence has shown that effects from oxidative stress induced damage of retinal or human retinal pigment epithelial (RPE) cells. Antioxidant supplementation is a plausible strategy to avoid oxidative stress and maintain the function of retina. d-Arg-2,6-dimethyltyrosine-Lys-Phe-NH2 (SS-31) has been used in the treatment of many diseases. In this study, we found that SS-31 attenuated hydrogen peroxide (H2 O2 )-induced loss of cell viability, reduced oxidative damage and cell apoptosis in RPE cells. HO-1, Trx-1 and Nrf-2 expression levels significantly increased on pre-treatment with SS-31 compared with the H2 O2 group. SS-31 inhibited apoptosis through the downregulation of Bax and the upregulation of Bcl-2. Our results suggest that SS-31 had a protective effect against H2 O2 treatment in ARPE-19 cells by enhancing the antioxidative enzymes expression and decreasing apoptosis, which could be considered a promising therapeutic intervention for retinal degeneration.

A Metabolic Landscape for Maintaining Retina Integrity and Function

Neurons have high metabolic demands that are almost exclusively met by glucose supplied from the bloodstream. Glucose is utilized in complex metabolic interactions between neurons and glia cells, described by the astrocyte-neuron lactate shuttle (ANLS) hypothesis. The neural retina faces similar energy demands to the rest of the brain, with additional high anabolic needs to support continuous renewal of photoreceptor outer segments. This demand is met by a fascinating variation of the ANLS in which photoreceptors are the central part of a metabolic landscape, using glucose and supplying surrounding cells with metabolic intermediates. In this review we summarize recent evidence on how neurons, in particular photoreceptors, meet their energy and biosynthetic requirements by comprising a metabolic landscape of interdependent cells.

Protective Effect of Quercetin on Sodium Iodate-Induced Retinal Apoptosis through the Reactive Oxygen Species-Mediated Mitochondrion-Dependent Pathway

Age-related macular degeneration (AMD) leads to gradual central vision loss and is the third leading cause of irreversible blindness worldwide. The underlying mechanisms for this progressive neurodegenerative disease remain unclear and there is currently no preventive treatment for dry AMD. Sodium iodate (NaIO₃) has been reported to induce AMD-like retinal pathology in mice. We established a mouse model for AMD to evaluate the effects of quercetin on NaIO₃-induced retinal apoptosis, and to investigate the pertinent underlying mechanisms. Our in vitro results indicated that quercetin protected human retinal pigment epithelium (ARPE-19) cells from NaIO₃-induced apoptosis by inhibiting reactive oxygen species production and loss of mitochondrial membrane potential as detected by Annexin V-FITC/PI flow cytometry. We also evaluated the relative expression of proteins in the apoptosis pathway. Quercetin downregulated the protein expressions of Bax, cleaved caspase-3, and cleaved PARP and upregulated the expression of Bcl-2 through reduced PI3K and pAKT expressions. Furthermore, our in vivo results indicated that quercetin improved retinal deformation and increased the thickness of both the outer nuclear layer and inner nuclear layer, whereas the expression of caspase-3 was inhibited. Taken together, these results demonstrate that quercetin could protect retinal pigment epithelium and the retina from NaIO₃-induced cell apoptosis via reactive oxygen species-mediated mitochondrial dysfunction, involving the PI3K/AKT signaling pathway. This suggests that quercetin has the potential to prevent and delay AMD and other retinal diseases involving NaIO₃-mediated apoptosis.

Modulated Electro-Hyperthermia Induces a Prominent Local Stress Response and Growth Inhibition in Mouse Breast Cancer Isografts

Modulated electro-hyperthermia (mEHT) is a selective cancer treatment used in human oncology complementing other therapies. During mEHT, a focused electromagnetic field (EMF) is generated within the tumor inducing cell death by thermal and nonthermal effects. Here we investigated molecular changes elicited by mEHT using multiplex methods in an aggressive, therapy-resistant triple negative breast cancer (TNBC) model. 4T1/4T07 isografts inoculated orthotopically into female BALB/c mice were treated with mEHT three to five times. mEHT induced the upregulation of the stress-related Hsp70 and cleaved caspase-3 proteins, resulting in effective inhibition of tumor growth and proliferation. Several acute stress response proteins, including protease inhibitors, coagulation and heat shock factors, and complement family members, were among the most upregulated treatment-related genes/proteins as revealed by next-generation sequencing (NGS), Nanostring and mass spectrometry (MS). pathway analysis demonstrated that several of these proteins belong to the response to stimulus pathway. Cell culture treatments confirmed that the source of these proteins was the tumor cells. The heat-shock factor inhibitor KRIBB11 reduced mEHT-induced complement factor 4 (C4) mRNA increase. In conclusion, mEHT monotherapy induced tumor growth inhibition and a complex stress response. Inhibition of this stress response is likely to enhance the effectiveness of mEHT and other cancer treatments.

Sulfasalazine attenuates tamoxifen-induced toxicity in human retinal pigment epithelial cells

Tamoxifen, a nonsteroidal estrogen receptor (ER) antagonist, is used routinely as a chemotherapeutic agent for ER-positive breast cancer. However, it is also causes side effects, including retinotoxicity. The retinal pigment epithelium (RPE) has been recognized as the primary target of tamoxifen-induced retinotoxicity. The RPE plays an essential physiological role in the normal functioning of the retina. Nonetheless, potential therapeutic agents to prevent tamoxifen-induced retinotoxicity in breast cancer patients have not been investigated. Here, we evaluated the action mechanisms of sulfasalazine against tamoxifen- induced RPE cell death. Tamoxifen induced reactive oxygen species (ROS)-mediated autophagic cell death and caspase-1-mediated pyroptosis in RPE cells. However, sulfasalazine reduced tamoxifen-induced total ROS and ROS-mediated autophagic RPE cell death. Also, mRNA levels of tamoxifen-induced pyroptosis-related genes, IL-1β, NLRP3, and procaspase-1, also decreased in the presence of sulfasalazine in RPE cells. Additionally, the mRNA levels of tamoxifen-induced AMD-related genes, such as complement factor I (CFI), complement factor H (CFH), apolipoprotein E (APOE), apolipoprotein J (APOJ), toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4), were downregulated in RPE cells. Together, these data provide novel insight into the therapeutic effects of sulfasalazine against tamoxifen-induced RPE cell death. [BMB Reports 2020; 53(5): 284-289].

Function and Dysfunction of Complement Factor H During Formation of Lipid-Rich Deposits

Complement-mediated inflammation or dysregulation in lipid metabolism are associated with the pathogenesis of several diseases. These include age-related macular degeneration (AMD), C3 glomerulonephritis (C3GN), dense deposit disease (DDD), atherosclerosis, and Alzheimer's disease (AD). In all these diseases, formation of characteristic lipid-rich deposits is evident. Here, we will discuss molecular mechanisms whereby dysfunction of complement, and especially of its key regulator factor H, could be involved in lipid accumulation and related inflammation. The genetic associations to factor H polymorphisms, the role of factor H in the resolution of inflammation in lipid-rich deposits, modification of macrophage functions, and complement-mediated clearance of apoptotic and damaged cells indicate that the function of factor H is crucial in limiting inflammation in these diseases.

Control of Complement Activation by the Long Pentraxin PTX3: Implications in Age-Related Macular Degeneration

Dysregulation of the complement system is central to age-related macular degeneration (AMD), the leading cause of blindness in the developed world. Most of the genetic variation associated with AMD resides in complement genes, with the greatest risk associated with polymorphisms in the complement factor H (CFH) gene; factor H (FH) is the major inhibitor of the alternative pathway (AP) of complement that specifically targets C3b and the AP C3 convertase. Long pentraxin 3 (PTX3) is a soluble pattern recognition molecule that has been proposed to inhibit AP activation via recruitment of FH. Although present in the human retina, if and how PTX3 plays a role in AMD is still unclear. In this work we demonstrated the presence of PTX3 in the human vitreous and studied the PTX3-FH-C3b crosstalk and its effects on complement activation in a model of retinal pigment epithelium (RPE). RPE cells cultured in inflammatory AMD-like conditions overexpressed the PTX3 protein, and up-regulated AP activating genes. PTX3 bound RPE cells in a physiological setting, however this interaction was reduced in inflammatory conditions, whereby PTX3 had no complement-inhibiting activity on inflamed RPE. However, on non-cellular surfaces, PTX3 formed a stable ternary complex with FH and C3b that acted as a “hot spot” for complement inhibition. Our findings suggest a protective role for PTX3 in response to complement dysregulation in AMD and point to a novel mechanism of complement regulation by this pentraxin with potential implications in pathology and pharmacology of AMD.

K284-6111 alleviates memory impairment and neuroinflammation in Tg2576 mice by inhibition of Chitinase-3-like 1 regulating ERK-dependent PTX3 pathway

Background

Alzheimer’s disease (AD) is one of the most prevalent neurodegenerative disorders characterized by gradual memory loss and neuropsychiatric symptoms. We have previously demonstrated that the 2-({3-[2-(1-cyclohexene-1-yl)ethyl]-6,7-dimethoxy-4-oxo-3,4-dihydro-2-quinazolinyl}sulfanyl)-N-(4-ethylphenyl)butanamide (K284-6111), the inhibitor of CHI3L1, has the inhibitory effect on memory impairment in Αβ infusion mouse model and on LPS-induced neuroinflammation in the murine BV-2 microglia and primary cultured astrocyte.

Methods

In the present study, we investigated the inhibitory effect of K284-6111 on memory dysfunction and neuroinflammation in Tg2576 transgenic mice, and a more detailed correlation of CHI3L1 and AD. To investigate the effects of K284-6111 on memory dysfunction, we administered K284-6111 (3 mg/kg, p.o.) daily for 4 weeks to Tg2576 mice, followed by behavioral tests of water maze test, probe test, and passive avoidance test.

Results

Administration of K284-6111 alleviated memory impairment in Tg2576 mice and had the effect of reducing the accumulation of Aβ and neuroinflammatory responses in the mouse brain. K284-6111 treatment also selectively inactivated ERK and NF-κB pathways, which were activated when CHI3L1 was overexpressed, in the mouse brain and in BV-2 cells. Web-based gene network analysis and our results of gene expression level in BV-2 cells showed that CHI3L1 is closely correlated with PTX3. Our result revealed that knockdown of PTX3 has an inhibitory effect on the production of inflammatory proteins and cytokines, and on the phosphorylation of ERK and IκBα.

Conclusion

These results suggest that K284-6111 could improve memory dysfunction by alleviating neuroinflammation through inhibiting CHI3L1 enhancing ERK-dependent PTX3 pathway.

Silencing of miR-23a attenuates hydrogen peroxide (H2O2) induced oxidative damages in ARPE-19 cells by upregulating GLS1: an in vitro study

BACKGROUND

Oxidative damages contributes to age-related macular degeneration (AMD) caused vision blindness, but the molecular mechanisms are still largely unknown.

OBJECTIVES

This study managed to investigate this issue by conducting in vitro experiments.

METHODS

Oxidative stress were evaluated by L-012 dye, DHE staining and MDA assay. CCK-8 and colony formation assay were conducted to examine cell proliferation. Cell death was evaluated by trypan blue staining and Annexin V-FITC/PI double staining method through flow cytometry (FCM). The binding sites of miR-23a and GLS1 mRNA were predicted by online miRDB database and validated by dual-luciferase reporter gene system. Real-Time qPCR for miR-23a levels and Western Blot for protein expressions.

RESULTS

The retinal pigment epithelial (RPE) cells (ARPE-19) were subjected to hydrogen peroxide (H2O2) stimulation to simulate AMD progression in vitro, and we identified a novel miR-23a/glutaminase-1 (GLS1) pathway that regulated H2O2 induced oxidative damages in ARPE-19 cells. Mechanistically, H2O2 induced oxidative stress, inhibited cell proliferation and induced cell death in ARPE-19 cells in a dose- and time-dependent manner. Also, H2O2 stimulation hindered cell invasion, migration and glutamine uptake in ARPE-19 cells. Interestingly, we proved that H2O2 increased miR-23a levels, while downregulated glutaminase-1 (GLS1) in ARPE-19 cells, and miR-23a targeted 3' untranslated region (3'UTR) of GLS1 mRNA for GLS1 degradation. Finally, our data suggested that silencing miR-23a upregulated GLS1 to reverse the detrimental effects of H2O2 treatment on ARPE-19 cells.

CONCLUSIONS

In general, analysis of the data suggested that miR-23a ablation upregulated GLS1 to attenuate H2O2 stimulation induced oxidative damages in ARPE-19 cells in vitro, and this study broadened our knowledge in this field, which might help to provide novel theranostic signatures for AMD.

Novel Programmed Cell Death as Therapeutic Targets in Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a leading cause of severe visual loss among the elderly. AMD patients are tormented by progressive central blurring/loss of vision and have limited therapeutic options to date. Drusen accumulation causing retinal pigment epithelial (RPE) cell damage is the hallmark of AMD pathogenesis, in which oxidative stress and inflammation are the well-known molecular mechanisms. However, the underlying mechanisms of how RPE responds when exposed to drusen are still poorly understood. Programmed cell death (PCD) plays an important role in cellular responses to stress and the regulation of homeostasis and diseases. Apart from the classical apoptosis, recent studies also discovered novel PCD pathways such as pyroptosis, necroptosis, and ferroptosis, which may contribute to RPE cell death in AMD. This evidence may yield new treatment targets for AMD. In this review, we summarized and analyzed recent advances on the association between novel PCD and AMD, proposing PCD's role as a therapeutic new target for future AMD treatment.