PGC-1α Protects RPE Cells of the Aging Retina against Oxidative Stress-Induced Degeneration through the Regulation of Senescence and Mitochondrial Quality Control. The Significance for AMD Pathogenesis

Mitochondrial quality control in non-exudative age-related macular degeneration: From molecular mechanisms to structural and functional recovery

Non-exudative age-related macular degeneration (NE-AMD) is the leading blindness cause in the elderly. Clinical and experimental evidence supports that early alterations in macular retinal pigment epithelium (RPE) mitochondria play a key role in NE-AMD-induced damage. Mitochondrial dynamics (biogenesis, fusion, fission, and mitophagy), which is under the central control of AMP-activated kinase (AMPK), in turn, determines mitochondrial quality. We have developed a NE-AMD model in C57BL/6J mice induced by unilateral superior cervical ganglionectomy (SCGx), which progressively reproduces the disease hallmarks circumscribed to the temporal region of the RPE/outer retina that exhibits several characteristics of the human macula. In this work we have studied RPE mitochondrial structure, dynamics, function, and AMPK role on these parameters' regulation at the nasal and temporal RPE from control eyes and at an early stage of experimental NE-AMD (i.e., 4 weeks post-SCGx). Although RPE mitochondrial mass was preserved, their function, which was higher at the temporal than at the nasal RPE in control eyes, was significantly decreased at 4 weeks post-SCGx at the same region. Mitochondria were bigger, more elongated, and with denser cristae at the temporal RPE from control eyes. Exclusively at the temporal RPE, SCGx severely affected mitochondrial morphology and dynamics, together with the levels of phosphorylated AMPK (p-AMPK). AMPK activation with metformin restored RPE p-AMPK levels, and mitochondrial dynamics, structure, and function at 4 weeks post-SCGx, as well as visual function and RPE/outer retina structure at 10 weeks post-SCGx. These results demonstrate a key role of the temporal RPE mitochondrial homeostasis as an early target for NE-AMD-induced damage, and that pharmacological AMPK activation could preserve mitochondrial morphology, dynamics, and function, and, consequently, avoid the functional and structural damage induced by NE-AMD.

Advances in Extraction Protocols, Degradation Methods, and Bioactivities of Proanthocyanidins

Proanthocyanidins, natural polyphenolic compounds abundantly present in plants, exhibit diverse bioactivities, including antioxidative, anti-inflammatory, and antibacterial effects. These bioactivities are intricately linked to the degree of polymerization of these compounds. Through a comprehensive analysis of recent domestic and international research, this article synthesizes the latest advancements in the extraction process, degradation methods, as well as the biological activities and underlying mechanisms of proanthocyanidins. Furthermore, future research endeavors should prioritize the refinement of extraction techniques, the elucidation of bioactive mechanisms, and the development of formulations with enhanced potency. This will maximize the utilization of proanthocyanidins across diverse applications.

Exploring the effect of Anshen Dingzhi prescription on hippocampal mitochondrial signals in single prolonged stress mouse model

HEADINGS ETHNOPHARMACOLOGICAL RELEVANCE

Anshen Dingzhi prescription (ADP), which was first published in the masterpiece of traditional Chinese Medicine in the Qing Dynasty, "Yi Xue Xin Wu" (1732 CE), is documented to interrupt panic-related disorders. However, the mechanism of its action is still not clear.

AIM OF THE STUDY

This study aims to investigate the effects of ADP on post-traumatic stress disorder (PTSD)-like behaviors and explore the mechanism from perspective of sirtuin1 (SIRT1)-peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α)-dependent mitochondrial function.

MATERIALS AND METHODS

The changes of SIRT1-PGC-1α signal and mitochondrial function were evaluated in the hippocampus of mice receiving single prolonged stress (SPS). Later, the roles of this signaling pathway played in fear memory generalization and anxiety-like behavior in SPS mice was investigated using two agonists of this signaling pathway. On this basis, the effects of ADP (36.8 mg/kg) with definite therapeutic effects, on mitochondrial function were investigated and further confirmed by a SIRT1 inhibitor. Finally, the possible components of ADP targeting PGC-1α were monitored through bioinformatics.

RESULTS

Compared with control mice, SIRT1-PGC-1α signal in the hippocampus was impaired in SPS mice, accompanied with dysfunction of mitochondria and abnormal expression of synaptic proteins. The agonists of SIRT1-PGC-1α signal, ZLN005, as well as resveratrol improved the behavioral changes of mice caused by SPS, reversed the decline of proteins in SIRT1-PGC-1α signal, mitochondrial dysfunction, and the abnormal expression of synaptic proteins. The fingerprint was established for the quality control of ADP. At a dose of 36.8 mg/kg, ADP could prevent fear memory generalization and anxiety-like behavior in SPS mice. Mechanically, ADP promoted SIRT1-PGC-1α signal and repaired mitochondrial function. Importantly, SIRT1 inhibitor, selisistat eliminated the ameliorative effects of ADP on behavioral and mitochondrial function. Through molecular docking simulation, the brain-entering components of ADP, including malkangunin, Rg5, fumarine, frutinone A, celabenzine, and inermin had high binding energy with PGC-1α.

CONCLUSION

Dysfunction of SIRT1-PGC-1α-dependent mitochondrial function is attributed to SPS-triggered fear generalization and anxiety-like behavior, and ADP could improve PTSD-like behaviors likely through activating this signaling pathway.

Targeting shared pathways in tauopathies and age-related macular degeneration: implications for novel therapies

The intricate parallels in structure and function between the human retina and the central nervous system designate the retina as a prospective avenue for understanding brain-related processes. This review extensively explores the shared physiopathological mechanisms connecting age-related macular degeneration (AMD) and proteinopathies, with a specific focus on tauopathies. The pivotal involvement of oxidative stress and cellular senescence emerges as key drivers of pathogenesis in both conditions. Uncovering these shared elements not only has the potential to enhance our understanding of intricate neurodegenerative diseases but also sets the stage for pioneering therapeutic approaches in AMD.

Role of immune inflammation regulated by macrophage in the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) can lead to irreversible impairment of visual function, and the number of patients with AMD has been increasing globally. The immunoinflammatory theory is an important pathogenic mechanism of AMD, with macrophages serving as the primary inflammatory infiltrating cells in AMD lesions. Its powerful immunoinflammatory regulatory function has attracted considerable attention. Herein, we provide an overview of the involvement of macrophage-regulated immunoinflammation in different stages of AMD. Additionally, we summarize novel therapeutic approaches for AMD, focusing on targeting macrophages, such as macrophage/microglia modulators, reduction of macrophage aggregation in the subretinal space, modulation of macrophage effector function, macrophage phenotypic alterations, and novel biomimetic nanocomposites development based on macrophage-associated functional properties. We aimed to provide a basis and reference for the further exploration of AMD pathogenesis, developmental influences, and new therapeutic approaches.

Roles of transmembrane protein 135 in mitochondrial and peroxisomal functions - implications for age-related retinal disease

Aging is the most significant risk factor for age-related diseases in general, which is true for age-related diseases in the eye including age-related macular degeneration (AMD). Therefore, in order to identify potential therapeutic targets for these diseases, it is crucial to understand the normal aging process and how its mis-regulation could cause age-related diseases at the molecular level. Recently, abnormal lipid metabolism has emerged as one major aspect of age-related symptoms in the retina. Animal models provide excellent means to identify and study factors that regulate lipid metabolism in relation to age-related symptoms. Central to this review is the role of transmembrane protein 135 (TMEM135) in the retina. TMEM135 was identified through the characterization of a mutant mouse strain exhibiting accelerated retinal aging and positional cloning of the responsible mutation within the gene, indicating the crucial role of TMEM135 in regulating the normal aging process in the retina. Over the past decade, the molecular functions of TMEM135 have been explored in various models and tissues, providing insights into the regulation of metabolism, particularly lipid metabolism, through its action in multiple organelles. Studies indicated that TMEM135 is a significant regulator of peroxisomes, mitochondria, and their interaction. Here, we provide an overview of the molecular functions of TMEM135 which is crucial for regulating mitochondria, peroxisomes, and lipids. The review also discusses the age-dependent phenotypes in mice with TMEM135 perturbations, emphasizing the importance of a balanced TMEM135 function for the health of the retina and other tissues including the heart, liver, and adipose tissue. Finally, we explore the potential roles of TMEM135 in human age-related retinal diseases, connecting its functions to the pathobiology of AMD.

Characterization and contribution of RPE senescence to Age-related macular degeneration in Tnfrsf10 knock out mice

Background

Retinal pigment epithelial cells (RPE) play vital role in the pathogenesis of age-related macular degeneration (AMD). Our laboratory has shown that RPE cellular senescence contributed to the pathophysiology of experimental AMD, and SASP members are involved in this process. Recently, we presented confirmatory evidence to earlier GWAS studies that dysregulation of tumor necrosis factor receptor superfamily 10A (TNFRSF10A) dysregulation leads to AMD development and is linked to RPE dysfunction. This study aims to investigate the contribution of RPE senescence to AMD pathophysiology using TNFRSF10A silenced human RPE (hRPE) cells and Tnfrsf10 KO mice.

Methods

Sub-confluent primary hRPE cells and TNFRSF10A silenced hRPE were exposed to stress-induced premature senescence with H2O2 (500 μM, 48h), and senescence-associated markers (βgal, p16, and p21) were analyzed by RT-PCR and WB analysis. The effect of H2O2-induced senescence in non-silenced and silenced hRPE on OXPHOS and glycolysis was determined using Seahorse XF96 analyzer. Male C57BL/6J Tnfrsf10 KO ( Tnfrsf10 -/- ) mice were used to study the regulation of senescence by TNFRSF10A in vivo . Expression of p16 and p21 in control and KO mice of varying ages were determined by RT-PCR, WB, and immunostaining analysis.

Results

The senescence-associated p16 and p21 showed a significant ( p < 0.01) upregulation with H2O2 induction at the gene (1.8- and 3-fold) and protein (3.2- and 4-fold) levels in hRPE cells. The protein expression of p16 and p21 was further significantly increased by co-treatment with siRNA ( p < 0.05 vs. H2O2). Mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) (pmol/min/total DNA) increased with senescence induction by H2O2 for 48h in control RPE, and knockdown of TNFRSF10A caused a further increase in OCR and ECAR. In addition, co-treatment with PKC activator significantly improved all parameters. Similarly, in vivo studies showed upregulation of p16 and p21 by RT-PCR, WB, and immunostaining analysis in RPE/choroid of Tnfrsf10 KO mice. When subjected to examination across distinct age groups, namely young (1-3 months), middle (6-9 months), and old (12-15 months) mice, a discernible age-related elevation in the expression of p16 and p21 was observed.

Conclusions

Our findings suggest that TNRSF10A is a regulator of regulates in RPE senescence. Further work on elucidating pathways of senescence will facilitate the development of new therapeutic targets for AMD.

Antioxidative Role of Heterophagy, Autophagy, and Mitophagy in the Retina and Their Association with the Age-Related Macular Degeneration (AMD) Etiopathogenesis

Age-related macular degeneration (AMD), an oxidative stress-linked neurodegenerative disease, leads to irreversible damage of the central retina and severe visual impairment. Advanced age and the long-standing influence of oxidative stress and oxidative cellular damage play crucial roles in AMD etiopathogenesis. Many authors emphasize the role of heterophagy, autophagy, and mitophagy in maintaining homeostasis in the retina. Relevantly modifying the activity of both macroautophagy and mitophagy pathways represents one of the new therapeutic strategies in AMD. Our review provides an overview of the antioxidative roles of heterophagy, autophagy, and mitophagy and presents associations between dysregulations of these molecular mechanisms and AMD etiopathogenesis. The authors performed an extensive analysis of the literature, employing PubMed and Google Scholar, complying with the 2013-2023 period, and using the following keywords: age-related macular degeneration, RPE cells, reactive oxygen species, oxidative stress, heterophagy, autophagy, and mitophagy. Heterophagy, autophagy, and mitophagy play antioxidative roles in the retina; however, they become sluggish and dysregulated with age and contribute to AMD development and progression. In the retina, antioxidative roles also play in RPE cells, NFE2L2 and PGC-1α proteins, NFE2L2/PGC-1α/ARE signaling cascade, Nrf2 factor, p62/SQSTM1/Keap1-Nrf2/ARE pathway, circulating miRNAs, and Yttrium oxide nanoparticles performed experimentally in animal studies.

The ginsenoside Rh2 protects porcine oocytes against aging and oxidative stress by regulating SIRT1 expression and mitochondrial activity

Post-ovulatory aging, a major problem faced by oocytes cultured in vitro, causes oxidative damage and mitochondrial dysfunction in oocytes. The ginsenoside Rh2 is one of the main monomeric components of ginseng, but its effects on porcine oocytes are unknown. In the present study, in vitro aging (IVA) and accelerated induction of aging using H₂O₂ resulted in DNA damage and an increased incidence of abnormal spindle formation in porcine oocytes. Rh2 supplementation increased the antioxidant capacity, reduced the occurrence of early apoptosis, and improved the development of in vitro fertilized blastocysts. It also rescued the abnormal aggregation of mitochondria and the decrease of the mitochondrial membrane potential under mitochondrial dysfunction. Meanwhile, Rh2 enhanced mRNA expression of the anti-aging and mitochondrial biogenesis-related genes silent information regulator of transcription 1 (SIRT1) and peroxisome proliferator-activated receptor coactivator 1-α (PGC-1α), and the antioxidant gene superoxide dismutase 1 (SOD1). The protection of porcine oocytes against aging and oxidative stress by Rh2 was confirmed using the SIRT1-specific inhibitor EX-527. Our results reveal that Rh2 upregulates SIRT1/PGC-1α to enhance mitochondrial function in porcine oocytes and improve their quality. Our study indicates that Rh2 can be used to prevent mitochondrial dysfunction in oocytes.

DAPL1 deficiency in mice impairs antioxidant defenses in the RPE and leads to retinal degeneration with AMD-like features

The decreased antioxidant capacity in the retinal pigment epithelium (RPE) is the hallmark of retinal degenerative diseases including age-related macular degeneration (AMD). Nevertheless, the exact regulatory mechanisms underlying the pathogenesis of retinal degenerations remain largely unknown. Here we show in mice that deficiencies in Dapl1, a susceptibility gene for human AMD, impair the antioxidant capacity of the RPE and lead to age-related retinal degeneration in the 18-month-old mice homozygous for a partial deletion of Dapl1. Dapl1-deficiency is associated with a reduction of the RPE's antioxidant capacity, and experimental re-expression of Dapl1 reverses this reduction and protects the retina from oxidative damage. Mechanistically, DAPL1 directly binds the transcription factor E2F4 and inhibits the expression of MYC, leading to upregulation of the transcription factor MITF and its targets NRF2 and PGC1α, both of which regulate the RPE's antioxidant function. When MITF is experimentally overexpressed in the RPE of DAPL1 deficient mice, antioxidation is restored and retinas are protected from degeneration. These findings suggest that the DAPL1-MITF axis functions as a novel regulator of the antioxidant defense system of the RPE and may play a critical role in the pathogenesis of age-related retinal degenerative diseases.

Choroidal Neovascular Membranes in Retinal and Choroidal Tumors: Origins, Mechanisms, and Effects

Choroidal neovascularizations are historically associated with exudative macular degeneration, nonetheless, they have been observed in nevus, melanoma, osteoma, and hemangioma involving the choroid and retina. This review aimed to elucidate the possible origins of neovascular membranes by examining in vivo and in vitro models compared to real clinical cases. Among the several potential mechanisms examined, particular attention was paid to histologic alterations and molecular cascades. Physical or biochemical resistance to vascular invasion from the choroid offered by Bruch's membrane, the role of fibroblast growth factor 2 and vascular endothelial growth factor, resident or recruited stem-like/progenitor cells, and other angiogenic promoters were taken into account. Even if the exact mechanisms are still partially obscure, experimental models are progressively enhancing our understanding of neovascularization etiology. Choroidal neovascularization (CNV) over melanoma, osteoma, and other tumors is not rare and is not contraindicative of malignancy as previously believed. In addition, CNV may represent a late complication of either benign or malignant choroidal tumors, stressing the importance of a long follow-up.

Design and evaluation of chrysin-loaded nanoemulsion against lithium/pilocarpine-induced status epilepticus in rats; emphasis on formulation, neuronal excitotoxicity, oxidative stress, microglia polarization, and AMPK/SIRT-1/PGC-1α pathway

OBJECTIVES

The present study aims to formulate and evaluate the efficacy of chrysin-loaded nanoemulsion (CH NE) against lithium/pilocarpine-induced epilepsy in rats, as well as, elucidate its effect on main epilepsy pathogenesis cornerstones; neuronal hyperactivity, oxidative stress, and neuroinflammation.

METHODS

NEs were characterized by droplet size, zeta potential, pH, in vitro release, accelerated and long-term stability studies. Anti-convulsant efficacy of the optimized formula and underlying mechanisms involved were assessed and compared to that from CH suspension given orally at a 30 folds higher dose.

RESULTS

Optimized formula displayed a droplet size of 48.09 ± 0.83 nm, PDI 0.25 ± 0.011, sustained release, and good stability. CH treatment reduced seizures scoring, corrected behavioral and histological changes induced by Li/Pilo. Moreover, CH restored neurotransmitters balance and oxidative stress markers levels. Besides, CH induced microglia polarization from M1 to M2 hindering inflammation induced by Li/Pilo. Also, CH restored energy metabolism homeostasis via regulating protein expression of AMPK/SIRT-1/PGC-1α pathway markers. CH NE formulation was found to significantly enhance drug delivery to rats' hippocampus compared to CH suspension.

CONCLUSION

Our findings prove the therapeutic efficacy of CH NE at a lower dose which could be a potential brain targeting platform to combat epilepsy.

Protective effects of Panax ginseng berry extract on blue light-induced retinal damage in ARPE-19 cells and mouse retina

Background

Age-related macular degeneration (AMD) is a significant visual disease that induces impaired vision and irreversible blindness in the elderly. However, the effects of ginseng berry extract (GBE) on the retina have not been studied. Therefore, this study aimed to investigate the protective effects of GBE on blue light (BL)-induced retinal damage and elucidate its underlying mechanisms in human retinal pigment epithelial cells (ARPE-19 cells) and Balb/c retina.

Methods

To investigate the effects and underlying mechanisms of GBE on retinal damage in vitro, we performed cell viability assay, pre-and post-treatment of sample, reactive oxygen species (ROS) assay, quantitative real-time PCR (qRT-PCR), and western immunoblotting using A2E-laden ARPE-19 cells with BL exposure. In addition, Balb/c mice were irradiated with BL to induce retinal degeneration and orally administrated with GBE (50, 100, 200 mg/kg). Using the harvested retina, we performed histological analysis (thickness of retinal layers), qRT-PCR, and western immunoblotting to elucidate the effects and mechanisms of GBE against retinal damage in vivo.

Results

GBE significantly inhibited BL-induced cell damage in ARPE-19 cells by activating the SIRT1/PGC-1α pathway, regulating NF-kB translocation, caspase 3 activation, PARP cleavage, expressions of apoptosis-related factors (BAX/BCL-2, LC3-Ⅱ, and p62), and ROS production. Furthermore, GBE prevented BL-induced retinal degeneration by restoring the thickness of retinal layers and suppressed inflammation and apoptosis via regulation of NF-kB and SIRT1/PGC-1α pathway, cleavage of caspase 3 and PARP, and expressions of apoptosis-related factors in vivo.

Conclusions

GBE could be a potential agent to prevent dry AMD and progression to wet AMD.

Traditional Chinese medicine in treating ischemic stroke by modulating mitochondria: A comprehensive overview of experimental studies

Ischemic stroke has been a prominent focus of scientific investigation owing to its high prevalence, complex pathogenesis, and difficulties in treatment. Mitochondria play an important role in cellular energy homeostasis and are involved in neuronal death following ischemic stroke. Hence, maintaining mitochondrial function is critical for neuronal survival and neurological improvement in ischemic stroke, and mitochondria are key therapeutic targets in cerebral stroke research. With the benefits of high efficacy, low cost, and high safety, traditional Chinese medicine (TCM) has great advantages in preventing and treating ischemic stroke. Accumulating studies have explored the effect of TCM in preventing and treating ischemic stroke from the perspective of regulating mitochondrial structure and function. In this review, we discuss the molecular mechanisms by which mitochondria are involved in ischemic stroke. Furthermore, we summarized the current advances in TCM in preventing and treating ischemic stroke by modulating mitochondria. We aimed to provide a new perspective and enlightenment for TCM in the prevention and treatment of ischemic stroke by modulating mitochondria.

Low expression of RBP4 in the vitreous humour of patients with proliferative diabetic retinopathy who underwent Conbercept intravitreal injection

Intravitreal injection of anti-VEGF antibodies has been widely used in the treatment of proliferative diabetic retinopathy (PDR). However, anti-VEGF drugs can exacerbate fibrosis and eventually lead to retinal detachment. To explore proteins closely related to fibrosis, we conducted proteomic analysis of human vitreous humour collected from PDR patients who have or have not intravitreal Conbercept (IVC) injection. Sixteen vitreous humour samples from PDR patients with preoperative IVC and 20 samples from those without preoperative IVC were examined. An immunodepletion kit was used to remove high-abundance vitreous proteins. Conbercept-induced changes were determined using a tandem mass tag-based quantitative proteomic strategy. Enzyme-linked immunosorbent assays were performed to confirm the concentrations of selected proteins and validate the proteomic results. Based on a false discovery rate between 0.05% and -0.05% and a fold-change > 1.5, 97 proteins were altered (49 higher levels and 48 lower levels) in response to IVC. Differentially expressed proteins were found in the extracellular and intracellular regions and were found to be involved in VEGF binding and VEGF-activated receptor activity. Protein-protein interactions indicated associations with fibrosis, neovascularisation and inflammatory signalling pathways. We found the low levels of RBP4 in the vitreous humour of PDR patients with IVC injection, as revealed by ELISA and proteomic profiling. Moreover, RBP4 significantly restored the mitochondrial function of HRMECs induced by AGEs and down regulated the level of glycolysis. Our study is the first to report that RBP4 decreases in the vitreous humour of PDR patients who underwent Conbercept treatment, thereby verifying the role of RBP4 in glucose metabolism. Results provide evidence for the potential mechanism underlying Conbercept-related fibrosis.

Crosstalk Between the Mitochondrial Dynamics and Oxidative Stress in Zinc-induced Cytotoxicity

Zinc is an essential trace element, which plays an important role in multiple biological activities. However, excessive exposure to zinc can cause toxic damage to living organism. Here, we investigated the relationship between oxidative stress and mitochondrial dynamics in the zinc-induced cytotoxicity. Results showed that excess exposure to zinc could significantly reduce cell viability and induce cell vacuolation in PK-15 cells. Additionally, zinc exposure caused mitochondrial dynamics disorder, manifested as mitochondrial fission, and the elevated mRNA level of Drp1 and downregulated mRNA levels of OPA1, Mfn1, and Mfn2. Meanwhile, zinc could induce oxidative damage, evidenced by the increasing levels of hydrogen peroxide, malondialdehyde, lipid peroxidation, oxidized form of nicotinamide adenine dinucleotide phosphate/nicotinamide adenine dinucleotide phosphate, oxidized glutathione/glutathione, superoxide dismutase activity, and the mRNA expression of SOD-1 and NOQ1, and decreasing levels of catalase activity, glutathione peroxidase activity, glutathione reductase activity, and the mRNA expression of CAT, and GPX1. Interestingly, N-acetyl-L-cysteine, an inhibitor for oxidative stress, could reduce the mitochondrial fission under zinc treatment. Besides, Mdivi-1, a mitochondrial fission inhibitor, could relieve oxidative stress caused by excess zinc. In general, these results suggested that mitochondrial fission and oxidative stress induced by zinc were interrelated in PK-15 cells, which is conducive to explore the new mechanism of zinc toxicity and proposes a theoretical foundation for selecting effective drugs to alleviate the toxic effects caused by zinc.

An Altered Neurovascular System in Aging-Related Eye Diseases

The eye has a complex and metabolically active neurovascular system. Repeated light injuries induce aging and trigger age-dependent eye diseases. Damage to blood vessels is related to the disruption of the blood-retinal barrier (BRB), altered cellular communication, disrupted mitochondrial functions, and exacerbated aggregated protein accumulation. Vascular complications, such as insufficient blood supply and BRB disruption, have been suggested to play a role in glaucoma, age-related macular degeneration (AMD), and Alzheimer's disease (AD), resulting in neuronal cell death. Neuronal loss can induce vision loss. In this review, we discuss the importance of the neurovascular system in the eye, especially in aging-related diseases such as glaucoma, AMD, and AD. Beneficial molecular pathways to prevent or slow down retinal pathologic processes will also be discussed.

Lycium barbarum L. and Salvia miltiorrhiza Bunge protect retinal pigment epithelial cells through endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum L. and Salvia miltiorrhiza Bunge (Gouqi and Danshen, LS) are traditional herbs for the treatment of retinal degeneration in China. LS have been integrated into pharmacopoeia and health care system of many countries around the world. However, the mechanisms by which LS protect retina are not fully clarified.

AIM OF THE STUDY

We aimed at exploration of the effect of LS on retinal pigment epithelium (RPE) cells apoptosis as well as the endoplasmic reticulum (ER) stress mechanisms.

MATERIAL AND METHODS

ARPE-19 cells were exposed to tunicamycin to induce ER stress, followed by LS treatment for 24 h. The cell morphology was photographed using the Incucyte S3 instrument, and the potential cytotoxic effect and viability were evaluated by CCK-8 assays. The Annexin V-FITC/PI staining and TUNEL assay were conducted to detect cells apoptotic. Western blot and digital PCR were used to detected related protein and gene expression.

RESULTS

The ARPE-19 cells are increased in number and aligned after treating with LS. 1 mg/ml is the LS high dose group dose and treatment with LS increased cell vitality. LS significantly inhibit ARPE-19 cells apoptosis. Moreover, LS were markedly decreased the expression levels of ER stress-related factors in the ARPE-19 cells.

CONCLUSIONS

This study reveals that LS relieve ARPE-19 cells apoptosis by inhibiting ER stress, and here we can speculate that LS have a certain protective effect on retina.

Lamin A/C impairments cause mitochondrial dysfunction by attenuating PGC1α and the NAMPT-NAD+ pathway

Mutations in the lamin A/C gene (LMNA) cause laminopathies such as the premature aging Hutchinson Gilford progeria syndrome (HGPS) and altered lamin A/C levels are found in diverse malignancies. The underlying lamin-associated mechanisms remain poorly understood. Here we report that lamin A/C-null mouse embryo fibroblasts (Lmna-/- MEFs) and human progerin-expressing HGPS fibroblasts both display reduced NAD+ levels, unstable mitochondrial DNA and attenuated bioenergetics. This mitochondrial dysfunction is associated with reduced chromatin recruitment (Lmna-/- MEFs) or low levels (HGPS) of PGC1α, the key transcription factor for mitochondrial homeostasis. Lmna-/- MEFs showed reduced expression of the NAD+-biosynthesis enzyme NAMPT and attenuated activity of the NAD+-dependent deacetylase SIRT1. We find high PARylation in lamin A/C-aberrant cells, further decreasing the NAD+ pool and consistent with impaired DNA base excision repair in both cell models, a condition that fuels DNA damage-induced PARylation under oxidative stress. Further, ATAC-sequencing revealed a substantially altered chromatin landscape in Lmna-/- MEFs, including aberrantly reduced accessibility at the Nampt gene promoter. Thus, we identified a new role of lamin A/C as a key modulator of mitochondrial function through impairments of PGC1α and the NAMPT-NAD+ pathway, with broader implications for the aging process.

Potential therapeutic role of SIRT1 in age- related hearing loss

Age-related hearing loss (ARHL) is a major public health burden worldwide that profoundly affects the daily life of elderly people. Silent information regulator 1 (SIRT1 or Sirtuin1), known as a regulator of the cell cycle, the balance of oxidation/antioxidant and mitochondrial function, has been proven to have anti-aging and life-extending effects, and its possible connection with ARHL has received increasing attention in recent years. This paper provides an overview of research on the connection between SIRT1 and ARHL. Topics cover both the functions of SIRT1 and its important role in ARHL. This review concludes with a look at possible research directions for ARHL in the future.

Hibiscus sabdariffa Extract Protects HaCaT Cells against Phenanthrene-Induced Toxicity through the Regulation of Constitutive Androstane Receptor/Pregnane X Receptor Pathway

Phenanthrene (Phe) exposure is associated with skin ageing, cardiotoxicity and developmental defects. Here, we investigated the mode of Phe toxicity in human keratinocytes (HaCaT cells) and the attenuation of toxicity on pre-treatment (6 h) with ethanol extract of Hibiscus sabdariffa calyxes (HS). Cell viability, reactive oxygen species (ROS) generation, mitochondrial membrane potential (ΔΨm) alteration, changes in the transcriptional activity of selected genes involved in phase I and II metabolism, antioxidant response and gluconeogenesis, western blot and docking studies were performed to determine the protective effect of HS against Phe. Phe (250 μM) induced cytotoxicity in HaCaT cells through AhR-independent, CAR/PXR/RXR-mediated activation of CYP1A1 and the subsequent alterations in phase I and II metabolism genes. Further, CYP1A1 activation by Phe induced ROS generation, reduced ΔΨm and modulated antioxidant response, phase II metabolism and gluconeogenesis-related gene expression. However, pre-treatment with HS extract restored the pathological changes observed upon Phe exposure through CYP1A1 inhibition. Docking studies showed the site-specific activation of PXR and CAR by Phe and inhibition of CYP1A1 and CYP3A4 by the bioactive compounds of HS similar to that of the positive controls tested. Our results conclude that HS extract can attenuate Phe-induced toxicity in HaCaT cells through CAR/PXR/RXR mediated inhibition of CYP1A1.

The Long-Term Effect of Blue-Light Blocking Spectacle Lenses on Adults’ Contrast Perception

Purpose

To evaluate the long-term effect of two different degrees of blue-light blocking (BB) spectacle lenses on adults’ contrast perception under various lighting conditions.

Methods

In total, 144 healthy adults aged 24.70 (±4.32 years) were recruited to this randomized controlled trial. The participants were randomly divided into three groups and used three different spectacle lenses (15% BB: 15% blue-blocking spectacle lenses; 30% BB: 30% blue-blocking spectacle lenses; RC: regular clear lenses serving as control). Contrast sensitivity under four light conditions (scotopic and photopic, both with/without glare) was measured using standard clinical tests at baseline, 1 month, 3 months and 6 months of use. The area under the log contrast sensitivity function (AULCSF) was also computed as an index for their overall contrast sensitivity across spatial frequencies.

Results

There was no significant difference in AULCSFs among the three types of spectacle lenses under any light condition (all P > 0.81). No statistical difference was found in the AULSCF among the four time points (all P > 0.39), with no interaction between the effects of group and time (all P > 0.42).

Conclusion

Wearing blue-light blocking lens had no clinically significant effect on adults’ long-term contrast perception under scotopic or photopic conditions, or with glare.

Role of Mitochondria in Retinal Pigment Epithelial Aging and Degeneration

Retinal pigment epithelial (RPE) cells form a monolayer between the neuroretina and choroid. It has multiple important functions, including acting as outer blood-retina barrier, maintaining the function of neuroretina and photoreceptors, participating in the visual cycle and regulating retinal immune response. Due to high oxidative stress environment, RPE cells are vulnerable to dysfunction, cellular senescence, and cell death, which underlies RPE aging and age-related diseases, including age-related macular degeneration (AMD). Mitochondria are the powerhouse of cells and a major source of cellular reactive oxygen species (ROS) that contribute to mitochondrial DNA damage, cell death, senescence, and age-related diseases. Mitochondria also undergo dynamic changes including fission/fusion, biogenesis and mitophagy for quality control in response to stresses. The role of mitochondria, especially mitochondrial dynamics, in RPE aging and age-related diseases, is still unclear. In this review, we summarize the current understanding of mitochondrial function, biogenesis and especially dynamics such as morphological changes and mitophagy in RPE aging and age-related RPE diseases, as well as in the biological processes of RPE cellular senescence and cell death. We also discuss the current preclinical and clinical research efforts to prevent or treat RPE degeneration by restoring mitochondrial function and dynamics.

Sirtuin 1 Induces Choroidal Neovascularization and Triggers Age-Related Macular Degeneration by Promoting LCN2 through SOX9 Deacetylation

Increasing studies have identified the function of sirtuin-1 (SIRT1) in ocular diseases. Hence, this study is aimed at exploring the potential role of SIRT1 in choroidal neovascularization- (CNV-) induced age-related macular degeneration (AMD) development and the associated mechanism. Expression of SIRT1/SOX9/LCN2 in the hypoxic cells was determined, and their interactions were predicted by bioinformatics websites and followed by the verification by luciferase assay and chromatin immunoprecipitation (ChIP). Their in vitro effects on hypoxic cells concerning cell viability, apoptosis, migration, and angiogenesis were detected through gain- and loss-of-function assays. Besides, their in vivo effect was explored using the established CNV mouse models. Highly expressed LCN2, SOX9, and SIRT1 were observed in hypoxic cells. LCN2 was increased by SOX9 and SIRT1 deacetylated SOX9 to promote its nuclear translocation, which further inhibited the viability of human retinal pigment epithelial cells and promoted cell apoptosis and angiogenesis as well as CNV-induced AMD formation. The relieving role of LCN2 inhibition on CNV-induced AMD without toxicity for mice was also demonstrated by in vivo experiments. Overall, SIRT1 promoted the formation of CNV-induced AMD through SOX9 deacetylation-caused LCN2 upregulation, representing a promising target for CNV-induced AMD management.

Evidence of retinal arteriolar narrowing in patients with autosomal-dominant polycystic kidney disease

Introduction

The aim of this study was to examine retinal vessels in autosomal dominant polycystic kidney disease (ADPKD) patients with normal kidney function and without diabetes mellitus.

Materials and Methods

We enrolled 39 adult individuals with ADPKD and 45 gender- and age-matched individuals as controls. A full ophthalmologic examination, including retinal vessel caliber and reactions to flicker stimulation analysis and grading of hypertensive retinopathy according to the Keith-Wagener classification, was performed.

Results

Multivariable analysis of ADPKD patients and controls, adjusted for age, gender, estimated glomerular filtration rate (e-GFR) and the presence of hypertension, revealed that ADPKD was an independent factor associated with lower arteriovenous ratio (AVR) values (by 0.069 on average, β = −0.50, p < 0.0001). The severity of hypertensive retinopathy according to the Keith-Wagener classification appeared to be more advanced in the ADPKD group than in the controls, despite the lack of vascular abnormalities, such as retinal hemorrhages, exudates, cotton wool spots or papilledema, as well as microaneurysms, which are very characteristic signs of ADPKD in other vascular beds.

Conclusions

Lower AVR values could be a specific pathophysiological ocular manifestation of systemic vasculopathy in the course of ADPKD.

Activation of LRP6 with HLY78 Attenuates Oxidative Stress and Neuronal Apoptosis via GSK3β/Sirt1/PGC-1α Pathway after ICH

Background

Oxidative stress and neuronal apoptosis have important roles in the pathogenesis after intracerebral hemorrhage (ICH). Previous studies have reported that low-density lipoprotein receptor-related protein 6 (LRP6) exerts neuroprotection in several neurological diseases. Herein, we investigate the role of LRP6 receptor activation with HLY78 to attenuate oxidative stress and neuronal apoptosis after ICH, as well as the underlying mechanism.

Methods

A total of 199 CD1 mice were used. ICH was induced via injection of autologous blood into the right basal ganglia. HLY78 was administered via intranasal injection at 1 h after ICH. To explore the underlying mechanism, LRP6 siRNA and selisistat, a Sirt1 selective antagonist, were injected intracerebroventricularly at 48 h before ICH induction. Neurobehavioral tests, Western blot, and immunofluorescence staining were performed.

Results

The expression of endogenous p-LRP6 was gradually increased and expressed on neurons after ICH. HLY78 significantly improved the short- and long-term neurobehavioral deficits after ICH, which was accompanied with decreased oxidative stress and neuronal apoptosis, as well as increased expression of p-GSK3β, Sirt1, and PGC-1α, as well as downregulation of Romo-1 and C-Caspase-3. LRP6 knockdown or Sirt1 inhibition abolished these effects of HLY78 after ICH.

Conclusion

Our results suggest that administration of HLY78 attenuated oxidative stress, neuronal apoptosis, and neurobehavioral impairments through the LRP6/GSK3β/Sirt1/PGC-1α signaling pathway after ICH.

Evidence of retinal arteriolar narrowing in patients with autosomal-dominant polycystic kidney disease

Introduction

The aim of this study was to examine retinal vessels in autosomal dominant polycystic kidney disease (ADPKD) patients with normal kidney function and without diabetes mellitus.

Materials and Methods

We enrolled 39 adult individuals with ADPKD and 45 gender- and age-matched individuals as controls. A full ophthalmologic examination, including retinal vessel caliber and reactions to flicker stimulation analysis and grading of hypertensive retinopathy according to the Keith-Wagener classification, was performed.

Results

Multivariable analysis of ADPKD patients and controls, adjusted for age, gender, estimated glomerular filtration rate (e-GFR) and the presence of hypertension, revealed that ADPKD was an independent factor associated with lower arteriovenous ratio (AVR) values (by 0.069 on average, β = −0.50, p < 0.0001). The severity of hypertensive retinopathy according to the Keith-Wagener classification appeared to be more advanced in the ADPKD group than in the controls, despite the lack of vascular abnormalities, such as retinal hemorrhages, exudates, cotton wool spots or papilledema, as well as microaneurysms, which are very characteristic signs of ADPKD in other vascular beds.

Conclusions

Lower AVR values could be a specific pathophysiological ocular manifestation of systemic vasculopathy in the course of ADPKD.

Long-Chain Polyunsaturated Fatty Acids and Their Metabolites Regulate Inflammation in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a blinding eye disease, whose incidence strongly increases with ages. The etiology of AMD is complex, including aging, abnormal lipid metabolism, chronic inflammation and oxidative stress. Long-chain polyunsaturated fatty acids (LCPUFA) are essential for ocular structures and functions. This review summarizes the regulatory effects of LCPUFA on inflammation in AMD. LCPUFA are related to aging, autophagy and chronic inflammation. They are metabolized to pro- and anti-inflammatory metabolites by various enzymes. These metabolites stimulate inflammation in response to oxidative stress, causing innate and acquired immune responses. This review also discusses the possible clinical applications, which provided novel targets for the prevention and treatment of AMD and other age-related diseases.

Therapeutic Effects of Sirtuin 1 Activator on Glaucoma Mice and the Regulation Mechanism of Mitogen-Activated Protein Kinase Pathway

The study focused on the therapeutic effects of resveratrol, sirtuin 1 (Sirt1) activator, on glaucoma, and its influence on mitogen-activated protein kinase (MAPK) pathway. Specifically, C57BL/6 mice were used and the glaucoma mouse model was established by intraperitoneal injection of N-methyl-D-aspartate (NMDA). According to different treatment methods, they were randomly rolled into 3 groups: control group (no treatment), model group (glaucoma mouse model), and resveratrol (Res) group (intraperitoneal injection of 20 mg/kg resveratrol solution on the basis of model group). The intraocular pressure was measured, and Sirt1 mRNA and protein expression was detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Subsequently, hematoxylin-eosin staining was used to observe histopathological morphology, the immunofluorescence labeling was used to identify retinal survival ganglia, and Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) and Western blot were for apoptotic cells determination and the expression of c-Jun N-terminal kinase (JNK), extracellular regulated protein kinase (ERK), and p38 protein in mitogen-activated protein kinase (MAPK) pathway, respectively. The model group showed lower intraocular pressure, Sirt1 mRNA and protein expression, number of survival retinal ganglion cells (RGCs), and thinner retina versus the control group (P < 0.05), but number of apoptotic RGCs and the phosphorylation levels of the three kinds of protein were higher (P < 0.05), and it exhibited no notable difference from the Res group (P > 0.05). Also, compared with the control group, the number of survival RGCs in the Res group was reduced (P < 0.05), but no notable difference was noted in the retinal thickness, the number of apoptotic RGCs, and the phosphorylation levels of the three kinds of protein (P > 0.05). In conclusion, resveratrol, the Sirt1 activator, can inhibit RGCs apoptosis through the MAPK signaling pathway and improve the pathological manifestations of glaucoma animal models, thus playing a protective role of the retina.

Role of the AMPK signalling pathway in the aetiopathogenesis of ocular diseases

BACKGROUND

AMP-activated protein kinase (AMPK) plays a precise role as a master regulator of cellular energy homeostasis. AMPK is activated in response to the signalling cues that exhaust cellular ATP levels such as hypoxia, ischaemia, glucose depletion and heat shock. As a central regulator of both lipid and glucose metabolism, AMPK is considered to be a potential therapeutic target for the treatment of various diseases, including eye disorders.

OBJECTIVE

To review all the shreds of evidence concerning the role of the AMPK signalling pathway in the pathogenesis of ocular diseases.

METHOD

Scientific data search and review of available information evaluating the influence of AMPK signalling on ocular diseases.

RESULTS

Review highlights the significance of AMPK signalling in the aetiopathogenesis of ocular diseases, including cataract, glaucoma, diabetic retinopathy, retinoblastoma, age-related macular degeneration, corneal diseases, etc. The review also provides the information on the AMPK-associated pathways with reference to ocular disease, which includes mitochondrial biogenesis, autophagy and regulation of inflammatory response.

CONCLUSION

The study concludes the role of AMPK in ocular diseases. There is growing interest in the therapeutic utilization of the AMPK pathway for ocular disease treatment. Furthermore, inhibition of AMPK signalling might represent more pertinent strategy than AMPK activation for ocular disease treatment. Such information will guide the development of more effective AMPK modulators for ocular diseases.[Formula: see text].

Complement Factor H-Related 3 Enhanced Inflammation and Complement Activation in Human RPE Cells

Complement Factor H-Related 3 (FHR-3) is a major regulator of the complement system, which is associated with different diseases, such as age-related macular degeneration (AMD). However, the non-canonical local, cellular functions of FHR-3 remained poorly understood. Here, we report that FHR-3 bound to oxidative stress epitopes and competed with FH for interaction. Furthermore, FHR-3 was internalized by viable RPE cells and modulated time-dependently complement component (C3, FB) and receptor (C3aR, CR3) expression of human RPE cells. Independently of any external blood-derived proteins, complement activation products were detected. Anaphylatoxin C3a was visualized in treated cells and showed a translocation from the cytoplasm to the cell membrane after FHR-3 exposure. Subsequently, FHR-3 induced a RPE cell dependent pro-inflammatory microenvironment. Inflammasome NLRP3 activation and pro-inflammatory cytokine secretion of IL-1ß, IL-18, IL-6 and TNF-α were induced after FHR-3-RPE interaction. Our previously published monoclonal anti-FHR-3 antibody, which was chimerized to reduce immunogenicity, RETC-2-ximab, ameliorated the effect of FHR-3 on ARPE-19 cells. Our studies suggest FHR-3 as an exogenous trigger molecule for the RPE cell “complosome” and as a putative target for a therapeutic approach for associated degenerative diseases.

Pharmacological modulation of cytokines correlating neuroinflammatory cascades in epileptogenesis

Epileptic seizure-induced brain injuries include activation of neuroimmune response with activation of microglia, astrocytes cells releasing neurotoxic inflammatory mediators underlies the pathophysiology of epilepsy. A wide spectrum of neuroinflammatory pathways is involved in neurodegeneration along with elevated levels of inflammatory mediators indicating the neuroinflammation in the epileptic brain. Therefore, the neuroimmune response is commonly observed in the epileptic brain, indicating elevated cytokine levels, providing an understanding of the neuroinflammatory mechanism contributing to seizures recurrence. Clinical and experimental-based evidence suggested the elevated levels of cytokines responsible for neuronal excitation and blood-brain barrier (BBB) dysfunctioning causing the drug resistance in epilepsy. Therefore, the understanding of the pathogenesis of neuroinflammation in epilepsy, including migration of microglial cells releasing the inflammatory cytokines indicating the correlation of elevated levels of inflammatory mediators (interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) triggering the generation or recurrence of seizures. The current review summarized the knowledge regarding elevated inflammatory mediators as immunomodulatory response correlating multiple neuroinflammatory NF-kB, RIPK, MAPK, ERK, JNK, JAK-STAT signaling cascades in epileptogenesis. Further selective targeting of inflammatory mediators provides beneficial therapeutic strategies for epilepsy.

Apelin-13-Mediated AMPK ameliorates endothelial barrier dysfunction in acute lung injury mice via improvement of mitochondrial function and autophagy

Maintaining the pulmonary endothelial barrier that prevents the exudation of inflammatory factors and proteins is the key to the treatment of acute lung injury (ALI). Apelin-13 plays an important role in vascular diseases; however, the protective effects of Apelin-13 on ALI with pulmonary endothelial barrier are unknown. Therefore, mice and human umbilical vein endothelial cells (HUVECs) were injured by LPS following Apelin-13 administration. ALI mice showed reduced pulmonary vascular permeability, adhesion junction, mitochondrial function, mitochondrial biogenesis, and autophagy compared to the control group. Apelin-13 administration in ALI mice ameliorated LPS-induced lung injury, pulmonary vascular permeability, mitochondrial function, and promoted autophagic flux in mice and HUVECs. However, the effect of Apelin-13 was reduced after AMPK inhibition using Compound C. These data suggest that Apelin-13 ameliorates pulmonary vascular permeability in mice with ALI induced by LPS, which may be related to enhanced phosphorylation of AMPK to regulate mitochondrial function and autophagy.

Therapeutic potential of PGC-1α in age-related macular degeneration (AMD) - the involvement of mitochondrial quality control, autophagy, and antioxidant response

INTRODUCTION

Age-related macular degeneration (AMD) is the leading, cause of sight loss in the elderly in the Western world. Most patients remain still without any treatment options. The targeting of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a transcription co-factor, is a putative therapy against AMD.

AREAS COVERED

The characteristics of AMD and their possible connection with PGC-1α as well as the transcriptional and post-transcriptional control of PGC-1α are discussed. The PGC-1α-driven control of mitochondrial functions, and its involvement in autophagy and antioxidant responses are also examined. Therapeutic possibilities via drugs and epigenetic approaches to enhance PGC-1α expression are discussed. Authors conducted a search of literature mainly from the recent decade from the PubMed database.

EXPERT OPINION

Therapy options in AMD could include PGC-1α activation or stabilization. This could be achieved by a direct elevation of PGC-1α activity, a stabilization or modification of its upstream activators and inhibitors by chemical compounds, like 5-Aminoimidazole-4-carboxamide riboside, metformin, and resveratrol. Furthermore, manipulations with epigenetic modifiers of PGC-1α expression, including miRNAs, e.g. miR-204, are considered. A therapy aimed at PGC-1α up-regulation may be possible in other disorders besides AMD, if they are associated with disturbances in the mitochondria-antioxidant response-autophagy axis.

Differential responses of AMD mitochondrial DNA haplogroups to PU-91, a mitochondria-targeting drug

Mitochondrial DNA (mtDNA) dysfunction and variation in mtDNA haplogroups play a key role in the etiology of Age-related Macular Degeneration (AMD). This study examined the response(s) of AMD ARPE-19 transmitochondrial cybrids having U, K, and J mtDNA haplogroups to treatment with a mitochondria-targeting PU-91 drug. PU-91 exerts its cytoprotective effects by upregulating PGC-1α (Peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha) which is a primary regulator of the mitochondrial biogenesis pathway. The effects of PU-91 drug were determined using cell-based assays and gene expression analyses. Our study revealed that AMD cybrids with different mtDNA haplogroups i.e., U, K, J haplogroups respond differentially to PU-91 drug treatment; and that the PU-91 drug increases viable cell number, improves mitochondrial health, and protects AMD cybrids against oxidative stress across the board irrespective of their haplogroup variation. This study suggests that mtDNA haplogroups may contribute to the differential responses of AMD cybrid cells to PU-91 drug in vitro and may also influence AMD patients' responses to drug treatment.

Low Birth Weight Disturbs the Intestinal Redox Status and Mitochondrial Morphology and Functions in Newborn Piglets

Simple Summary

Low birth-weight piglets normally have a higher growth retardation and are more prone to disease such as diarrhea compared to NBW piglets, which are strongly associated with intestinal health, body redox status and mitochondrial morphology and function. The present study showed that low birth-weight piglets exhibited abnormal intestinal development and impaired intestinal barrier function and redox status when compared to normal- birth-weight piglets. Furthermore, we found that the impaired mitochondrial structure and functions may be one of the main causes of intestinal dysfunction in low birth-weight piglets. These results provided insights for the mechanisms of intestinal dysfunction in low birth-weight piglets.

Abstract

Low birth-weight (LBW) neonates exhibit a lower growth rate and impaired intestinal development. However, the reasons for abnormal development of small intestine in LBW piglets have not been widely studied. The present study focused on the redox status and mitochondrial morphology and functions of the small intestine in LBW newborn piglets. Ten newborn normal birth-weight (NBW) piglets and LBW piglets from 10 primiparous sows with the same parturition day were selected and sampled immediately without sucking colostrum. The small intestine tissues were collected and measured. Compared with NBW newborn piglets, LBW newborn piglets had a significantly decreased length and weight of the small intestine (p < 0.05) as well as the villus height/crypt depth (V/C) index in the jejunum (p < 0.05). Furthermore, LBW piglets had a lower gene expression of tight junction protein zonula occluden-1 (ZO1), claudin 1, antioxidant enzyme catalase (CAT), glutathione peroxidase (GPX) and heme oxygenase-1 (HO-1) in jejunum (p < 0.05). Meanwhile, LBW induced mitochondrial vacuolation and significantly decreased the mRNA expression of PPARγ coactivator-1α (PGC-1α) (p < 0.05) and tended to decrease the expression of cytochrome coxidase IV (Ccox IV) (p = 0.07) and cytochrome C (Cytc) (p = 0.08). In conclusion, LBW newborn piglets showed an abnormal development of the small intestine and disturbed redox status, and this may be caused by impaired morphology and the functions of mitochondria in the jejunum.

Newly-found functions of metformin for the prevention and treatment of age-related macular degeneration

Metformin (MET), a first-line oral agent used to treat diabetes, exerts its function mainly by activating adenosine monophosphate-activated protein. The accumulation of oxidized phospholipids in the outer layer of the retina plays a key role in retinal pigment epithelium (RPE) cells death and the formation of choroidal neovascularization (CNV), which mean the development of age-related macular degeneration (AMD). Recent studies have shown that MET can regulate lipid metabolism, inhibit inflammation, and prohibit retinal cell death and CNV formation due to various pathological factors. Here, newly discovered functions of MET that may be used for the prevention and treatment of AMD were reviewed.

Physical exercise prevents age-related heart dysfunction induced by high-salt intake and heart salt-specific overexpression in Drosophila

A long-term high-salt intake (HSI) seems to accelerate cardiac aging and age-related diseases, but the molecular mechanism is still not entirely clear. Exercise is an effective way to delay cardiac aging. However, it remains unclear whether long-term exercise (LTE) can protect heart from aging induced by high-salt stress. In this study, heart CG2196(salt) specific overexpression (HSSO) and RNAi (HSSR) was constructed by using the UAS/hand-Gal4 system in Drosophila. Flies were given exercise and a high-salt diet intervention from 1 to 5 weeks of age. Results showed that HSSR and LTE remarkably prevented heart from accelerated age-related defects caused by HSI and HSSO, and these defects included a marked increase in heart period, arrhythmia index, malondialdehyde (MDA) level, salt expression, and dTOR expression, and a marked decrease in fractional shortening, SOD activity level, dFOXO expression, PGC-1α expression, and the number of mitochondria and myofibrils. The combination of HSSR and LTE could better protect the aging heart from the damage of HSI. Therefore, current evidences suggested that LTE resisted HSI-induced heart presenility via blocking CG2196(salt)/TOR/oxidative stress and activating dFOXO/PGC-1α. LTE also reversed heart presenility induced by cardiac-salt overexpression via activating dFOXO/PGC-1α and blocking TOR/oxidative stress.

A Systematic Review of Carotenoids in the Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of modifiable vision loss in older adults. Chronic oxidative injury and compromised antioxidant defenses represent essential drivers in the development of retinal neurodegeneration. Overwhelming free radical species formation results in mitochondrial dysfunction, as well as cellular and metabolic imbalance, which becomes exacerbated with increasing age. Thus, the depletion of systemic antioxidant capacity further proliferates oxidative stress in AMD-affected eyes, resulting in loss of photoreceptors, neuroinflammation, and ultimately atrophy within the retinal tissue. The aim of this systematic review is to examine the neuroprotective potential of the xanthophyll carotenoids lutein, zeaxanthin, and meso-zeaxanthin on retinal neurodegeneration for the purpose of adjunctive nutraceutical strategy in the management of AMD. A comprehensive literature review was performed to retrieve 55 eligible publications, using four database searches from PubMed, Embase, Cochrane Library, and the Web of Science. Epidemiology studies indicated an enhanced risk reduction against late AMD with greater dietary consumption of carotenoids, meanwhile greater concentrations in macular pigment demonstrated significant improvements in visual function among AMD patients. Collectively, evidence strongly suggests that carotenoid vitamin therapies offer remarkable synergic protection in the neurosensory retina, with the potential to serve as adjunctive nutraceutical therapy in the management of established AMD, albeit these benefits may vary among different stages of disease.

Quercetin Alleviates the Accumulation of Superoxide in Sodium Iodate-Induced Retinal Autophagy by Regulating Mitochondrial Reactive Oxygen Species Homeostasis through Enhanced Deacetyl-SOD2 via the Nrf2-PGC-1α-Sirt1 Pathway

Oxidative damage of retinal pigment epithelium (RPE) cells plays an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Quercetin, a bioactive flavonoid compound, has been shown to have a protective effect against oxidative stress-induced cell apoptosis and inflammation in RPE cells; however, the detailed mechanism underlying this protective effect is unclear. Therefore, the aim of this study was to investigate the regulatory mechanism of quercetin in a sodium iodate (NaIO₃)-induced retinal damage. The clinical features of the mice, the production of oxidative stress, and the activity of autophagy and mitochondrial biogenesis were examined. In the mouse model, NaIO₃ treatment caused changes in the retinal structure and reduced pupil constriction, and quercetin treatment reversed the oxidative stress-related pathology by decreasing the level of superoxide dismutase 2 (SOD2) while enhancing the serum levels of catalase and glutathione. The increased level of reactive oxygen species in the NaIO₃-treated ARPE19 cells was improved by treatment with quercetin, accompanied by a reduction in autophagy and mitochondrial biogenesis. Our findings indicated that the effects of quercetin on regulating the generation of mtROS were dependent on increased levels of deacetyl-SOD2 through the Nrf2-PGC-1α-Sirt1 signaling pathway. These results demonstrated that quercetin may have potential therapeutic efficacy for the treatment of AMD through the regulation of mtROS homeostasis.

Potential of Telomerase in Age-Related Macular Degeneration-Involvement of Senescence, DNA Damage Response and Autophagy and a Key Role of PGC-1α

Age-related macular degeneration (AMD), the main cause of vision loss in the elderly, is associated with oxidation in the retina cells promoting telomere attrition. Activation of telomerase was reported to improve macular functions in AMD patients. The catalytic subunit of human telomerase (hTERT) may directly interact with proteins important for senescence, DNA damage response, and autophagy, which are impaired in AMD. hTERT interaction with mTORC1 (mTOR (mechanistic target of rapamycin) complex 1) and PINK1 (PTEN-induced kinase 1) activates macroautophagy and mitophagy, respectively, and removes cellular debris accumulated over AMD progression. Ectopic expression of telomerase in retinal pigment epithelium (RPE) cells lengthened telomeres, reduced senescence, and extended their lifespan. These effects provide evidence for the potential of telomerase in AMD therapy. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) may be involved in AMD pathogenesis through decreasing oxidative stress and senescence, regulation of vascular endothelial growth factor (VEGF), and improving autophagy. PGC-1α and TERT form an inhibitory positive feedback loop. In conclusion, telomerase activation and its ectopic expression in RPE cells, as well as controlled clinical trials on the effects of telomerase activation in AMD patients, are justified and should be assisted by PGC-1α modulators to increase the therapeutic potential of telomerase in AMD.

Sulforaphane inhibits blue light-induced inflammation and apoptosis by upregulating the SIRT1/PGC-1α/Nrf2 pathway and autophagy in retinal pigment epithelial cells

The present study elucidated mechanisms through which sulforaphane (SFN) protects retinal pigment epithelial (RPE) cells from blue light-induced impairment. SFN could activate the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increase the expression of the heme oxygenease-1 (HO-1) gene and production of glutathione. SFN reduced blue light-induced oxidative stress, and effectively activated cytoprotective components including Nrf-2, HO-1, thioredoxin-1, and glutathione. The protective effect of SFN on blue light-induced injury was blocked by the Nrf2 inhibitor ML385, suggesting that the SFN-induced Nrf2 pathway is involved in the cytoprotective effect of SFN. SFN inhibited intercellular adhesion molecule-1 expression induced by TNF-α or blue light, suggesting the anti-inflammatory activity of SFN. The inhibitory effect of SFN was associated with the blocking of NF-κB p65 nuclear translocation in blue light-exposed RPE cells. SFN protected RPE cells from blue light-induced interruption of the mitochondrial membrane potential and reduction of the Bcl-2/Bax ratio and cleaved caspase-3 and PARP-1 expression, suggesting the antiapoptotic activity of SFN. SFN alone or together with blue light exposure increased the expression of the autophagy-related proteins LC3BII and p62. An autophagy inhibitor, 3-MA, inhibited the protective effect of SFN on blue light-induced cell damage. SFN increased sirtuin-1 (SIRT1) expression; however, treatment with blue light induced peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) expression. Our study results demonstrated that SFN exerts its protective effect under blue light exposure by maintaining the Nrf2-related redox state and upregulating SIRT1 and PGC-1α expression and autophagy.

Regulation of Endothelial and Vascular Functions by Carbon Monoxide via Crosstalk With Nitric Oxide

Carbon monoxide (CO), generated by heme oxygenase (HO), has been considered a signaling molecule in both the cardiovascular and central nervous systems. The biological function of the HO/CO axis is mostly related to other gaseous molecules, including nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS). Healthy blood vessels are essential for the maintenance of tissue homeostasis and whole-body metabolism; however, decreased or impaired vascular function is a high-risk factor of cardiovascular and neuronal diseases. Accumulating evidence supports that the interplay between CO and NO plays a crucial role in vascular homeostasis and regeneration by improving endothelial function. Moreover, endothelial cells communicate with neighboring cells, such as, smooth muscle cells, immune cells, pericytes, and astrocytes in the periphery and neuronal vascular systems. Endogenous CO could mediate the cell-cell communication and improve the physiological functions of the cardiovascular and neurovascular systems via crosstalk with NO. Thus, a forward, positive feedback circuit between HO/CO and NOS/NO pathways can maintain cardiovascular and neurovascular homeostasis and prevent various human diseases. We discussed the crucial role of CO-NO crosstalk in the cardiovascular and neurovascular systems.

KRT8 (keratin 8) attenuates necrotic cell death by facilitating mitochondrial fission-mediated mitophagy through interaction with PLEC (plectin)

Dysregulation of mitochondrial homeostasis and accumulation of damaged mitochondria cause degenerative diseases such as age-related macular degeneration (AMD). We studied the effects of the intermediate cytofilament KRT8 (keratin 8) on mitochondrial homeostasis in relation to the morphology and function of mitochondria in retinal pigment epithelial cells under oxidative stress. When the mitochondria were damaged owing to oxidative stress, the damaged mitochondria were readily disposed of via mitophagy following mitochondrial fission. During this process, KRT8 was found to physically interact with the mitochondria through PLEC (plectin) and facilitate the mitochondrial fission-mediated mitophagy. However, the association between PLEC-anchoring mitochondria and KRT8 was dwindled by KRT8 phosphorylation under oxidative stress. The efficient KRT8-facilitated mitophagy flux suppressed the accumulation of damaged mitochondria and consequently diminished necrotic cell death under oxidative stress. Thus, by facilitating mitophagy, KRT8 protects RPE cells against necrotic cell death due to oxidative stress.

PGC-1α protects from myocardial ischaemia-reperfusion injury by regulating mitonuclear communication

The recovery of blood supply after a period of myocardial ischaemia does not restore the heart function and instead results in a serious dysfunction called myocardial ischaemia‐reperfusion injury (IRI), which involves several complex pathophysiological processes. Mitochondria have a wide range of functions in maintaining the cellular energy supply, cell signalling and programmed cell death. When mitochondrial function is insufficient or disordered, it may have adverse effects on myocardial ischaemia‐reperfusion and therefore mitochondrial dysfunction caused by oxidative stress a core molecular mechanism of IRI. Peroxisome proliferator‐activated receptor gamma co‐activator 1α (PGC‐1α) is an important antioxidant molecule found in mitochondria. However, its role in IRI has not yet been systematically summarized. In this review, we speculate the role of PGC‐1α as a key regulator of mitonuclear communication, which may interacts with nuclear factor, erythroid 2 like ‐1 and ‐2 (NRF‐1/2) to inhibit mitochondrial oxidative stress, promote the clearance of damaged mitochondria, enhance mitochondrial biogenesis, and reduce the burden of IRI.

Superior Properties of N-Acetylcysteine Ethyl Ester over N-Acetyl Cysteine to Prevent Retinal Pigment Epithelial Cells Oxidative Damage

Oxidative stress plays a key role in the pathophysiology of retinal diseases, including age-related macular degeneration (AMD) and diabetic retinopathy, which are the major causes of irreversible blindness in developed countries. An excess of reactive oxygen species (ROS) can directly cause functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells, and retinal ganglion cells. Antioxidants may represent a preventive/therapeutic strategy and reduce the risk of progression of AMD. Among antioxidants, N-acetyl-L-cysteine (NAC) is widely studied and has been proposed to have therapeutic benefit in treating AMD by mitigating oxidative damage in RPE. Here, we demonstrate that N-acetyl-L-cysteine ethyl ester (NACET), a lipophilic cell-permeable cysteine derivative, increases the viability in oxidative stressed RPE cells more efficiently than NAC by reacting directly and more rapidly with oxidizing agents, and that NACET, but not NAC, pretreatment predisposes RPE cells to oxidative stress resistance and increases the intracellular reduced glutathione (GSH) pool available to act as natural antioxidant defense. Moreover, we demonstrate the ability of NACET to increase GSH levels in rats' eyes after oral administration. In conclusion, even if experiments in AMD animal models are still needed, our data suggest that NACET may play an important role in preventing and treating retinal diseases associated with oxidative stress, and may represent a valid and more efficient alternative to NAC in therapeutic protocols in which NAC has already shown promising results.

Uncoupling proteins in the mitochondrial defense against oxidative stress

Oxidative stress is a major component of most major retinal diseases. Many extrinsic anti-oxidative strategies have been insufficient at counteracting one of the predominant intrinsic sources of reactive oxygen species (ROS), mitochondria. The proton gradient across the inner mitochondrial membrane is a key driving force for mitochondrial ROS production, and this gradient can be modulated by members of the mitochondrial uncoupling protein (UCP) family. Of the UCPs, UCP2 shows a widespread distribution and has been shown to uncouple oxidative phosphorylation, with concomitant decreases in ROS production. Genetic studies using transgenic and knockout mice have documented the ability of increased UCP2 activity to provide neuroprotection in models of a number of diseases, including retinal diseases, indicating that it is a strong candidate for a therapeutic target. Molecular studies have identified the structural mechanism of action of UCP2 and have detailed the ways in which its expression and activity can be controlled at the transcriptional, translational and posttranslational levels. These studies suggest a number of ways in control of UCP2 expression and activity can be used therapeutically for both acute and chronic conditions. The development of such therapeutic approaches will greatly increase the tools available to combat a broad range of serious retinal diseases.

ShenmaYizhi Decoction Improves the Mitochondrial Structure in the Brain and Ameliorates Cognitive Impairment in VCI Rats via the AMPK/UCP2 Signaling Pathway

BACKGROUND

ShenmaYizhi decoction (SMYZD) is an effective prescription of traditional Chinese medicine used to treat vascular dementia (VD). Modern research methods have identified its active ingredients clearly as gastrodin, ferulic acid, ginsenosides, and β-sitosterol. Chronic cerebral hypoperfusion is a driving factor or risk factor for VD, which leads to the disturbance of mitochondrial structure and function.

PURPOSE

To observe whether SMYZD improves cognitive impairment by improving mitochondrial structure and function.

METHODS

Forty adult rats with vascular cognitive impairment (VCI) caused by the bilateral ligation of common carotid arteries were divided into four groups randomly, including the model group, donepezil group, and low-dose and high-dose SMYZD groups, with 10 rats in each group. Additionally, a sham group was established with 10 rats as the control group. The treatment groups were administered donepezil and two different dosages of SMYZD. The donepezil group was administered 0.45 mg/kg/d donepezil, and the SMYZ-L group was administered 2.97 g/kg/d SMYZ, which were equivalent to the clinical dosage. The SMYZ-H group was administered 11.88 g/kg/d SMYZ, which is 4 times higher than the clinically equivalent dosage. A sham-operated group was used as the control group and administered an equal volume of distilled water. The rats were treated by gavage for 8 consecutive weeks. Morris water maze (MWM) test was performed to evaluate the learning and memory ability. The mitochondria of brain tissue were extracted from brain for further test. Mitochondrial morphology and the signal path of AMPK/PPARα/PGC-1α/UCP2 in mitochondria were detected.

RESULTS

With the SMYZD intervention, behavioral performance of rats and pathological changes of mitochondria of brain tissue were significantly improved. In the serum, SOD, GSH-Px, and GSH activities were increased, and the MDA content was decreased. Moreover, the AMPK, PPARα, PGC-1α, UCP2, and ATP5A mRNA and protein expression levels were also reversed by SMYZD.

CONCLUSION

SMYZD may provide a potential therapeutic strategy via activating the AMPK/PPARα/PGC-1α/UCP2 signal pathway to improve mitochondrial structure and energy metabolism thereby alleviate vascular cognitive impairment.

Melanocortin 1 receptor attenuates early brain injury following subarachnoid hemorrhage by controlling mitochondrial metabolism via AMPK/SIRT1/PGC-1α pathway in rats

Mitochondria-mediated oxidative stress and apoptosis contribute greatly to early brain injury (EBI) following subarachnoid hemorrhage (SAH). This study hypothesized that activation of melanocortin 1 receptor (MC1R), using BMS-470539, attenuates EBI by controlling mitochondrial metabolism after SAH. Methods: We utilized BMS-470539, MSG-606, selisistat, and PGC-1α to verify the neuroprotective effects of MC1R. We evaluated short- and long-term neurobehavior after SAH. Western blotting, immunofluorescence, and Golgi staining techniques were performed to assess changes in protein levels. Results: The results of western blotting suggested that the expression of SIRT1 and PGC-1α were increased, reaching their peaks at 24 h following SAH. Moreover, BMS-470539 treatment notably attenuated neurological deficits, and also reduced long-term spatial learning and memory impairments caused by SAH. The underlying neuroprotective mechanisms of the BMS-470539/MC1R system were mediated through the suppression of oxidative stress, apoptosis, and mitochondrial fission by increasing the levels of SIRT1, PGC-1α, UCP2, SOD, GPx, Bcl-2, cyto-Drp1, and ATP, while decreasing the levels of cleaved caspase-3, Bax, mito-Drp1, ROS, GSH/GSSG, and NADPH/NADP+ ratios. The neuroprotective effects of the BMS-470539/MC1R system were significantly abolished by MSG-606, selisistat, and PGC-1α siRNA. Conclusions: The activation of MC1R with BMS-470539 significantly attenuated EBI after SAH by suppressing the oxidative stress, apoptosis, and mitochondrial fission through the AMPK/SIRT1/PGC-1α signaling pathway.