A detailed analysis of hydrogen peroxide-induced cell death in primary neuronal culture

Inactivation of Laforin Phosphatase and Increased Glucose Uptake Underlie Glycogen Synthase-Mediated Neuronal Survival Under Oxidative Stress

Recent studies demonstrate that exposure of neurons to physiological stressors triggers glycogen synthase (GS) activation and glycogen synthesis as a transient cell survival mechanism. However, the mechanisms that regulate glycogen synthesis during stress and its role in neuronal physiology remain unclear. This study investigated the mechanisms that guide GS activation and glycogen accumulation under oxidative stress conditions as a model stressor. We use neuronal cell lines to demonstrate that hydrogen peroxide-induced oxidative stress activates GS and glycogen synthesis in neuronal cells. We further demonstrate that the stress-induced glycogen accumulation is dependent on the membrane localization of the Glut3 glucose transporters and increased glucose uptake during stress. The stress-induced activation of glycogen synthesis, however, is independent of intracellular glucose level, suggesting a parallel mechanism for activating GS and glucose uptake in neurons under physiological stress. We demonstrate that oxidative stress results in the inactivation of laforin phosphatase, leading to the membrane localization of Glut3 and activation of GS. Using the Drosophila model, we demonstrate that increased GS activity and concomitant glycogen accumulation are pro-survival mechanisms for neurons under oxidative stress. Our study thus offers novel insights into the pathways that regulate glycogen metabolism in neurons under oxidative stress and underscores their importance for neuronal survival.

Phenotyping the Chemical Communications of the Intestinal Microbiota and the Host: Secondary Bile Acids as Postbiotics

The current definition of a postbiotic is a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host". Postbiotics can be mainly classified as metabolites, derived from intestinal bacterial fermentation, or structural components, as intrinsic constituents of the microbial cell. Secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA) are bacterial metabolites generated by the enzymatic modifications of primary bile acids by microbial enzymes. Secondary bile acids function as receptor ligands modulating the activity of a family of bile-acid-regulated receptors (BARRs), including GPBAR1, Vitamin D (VDR) receptor and RORγT expressed by various cell types within the entire human body. Secondary bile acids integrate the definition of postbiotics, exerting potential beneficial effects on human health given their ability to regulate multiple biological processes such as glucose metabolism, energy expenditure and inflammation/immunity. Although there is evidence that bile acids might be harmful to the intestine, most of this evidence does not account for intestinal dysbiosis. This review examines this novel conceptual framework of secondary bile acids as postbiotics and how these mediators participate in maintaining host health.

"Bioactive" Therapeutic Contact Lens Triggered by Biomimetic Chiral Helical Nanoarchitectonics for Rapid Corneal Repair

Consistent corneal epithelial injury would cause chronic inflammation, neovascularization, and even corneal scarring, resulting in vision loss. Rapid repair is crucial for treatment, within which the use of therapeutic contact lenses presents great promise. A great challenge is how to achieve rapid repair of severely deficient corneal epithelium and regulation of the oxidative stress environment simultaneously. Herein, a "bioactive" therapeutic contact lens, mimicking the layered helical structure of the native cornea, is designed based on the assembly of cellulose nanocrystals (CNCs) inside poly(hydroxyethyl methacrylate) (PHEMA) with CeOx formed on the CNCs' surface (CeOx/CNC@CNC-PHEMA). The obtained CeOx/CNC@CNC-PHEMA hydrogel possesses a chiral helical structure that regulates the microenvironment, and the nanoscaled CeOx on the CNCs' surface (CeOx/CNC) acts as a reactive oxygen species (ROS) scavenger and triggers a "bioactive" therapeutic contact lens for rapid corneal repair. This hydrogel meets the conditions of a therapeutic contact lens, including high degree of transparency, excellent mechanical properties, great ROS-scavenging efficacy, and a significant enhancement of biocompatibility. Importantly, the adhesion and proliferation of human corneal epithelial cells on the CeOx/CNC@CNC-PHEMA hydrogels are successful. An in vitro corneal oxidative damage model and in vivo animal model of corneal injury experiments were conducted, and results revealed that the hydrogel realized rapid corneal epithelial cells migration with antioxidant, anti-inflammatory, and antineovascular effects, achieving modulation of the ocular surface microenvironment, evidencing a "bioactive" property of the hydrogel as a therapeutic contact lens. This biotopological hydrogel with a biomimetic corneal architecture has provided a rational strategy for rapid corneal repair.

Progranulin enhances the engraftment of transplanted human iPS cell-derived cerebral neurons

Cerebral organoids (COs) in cell replacement therapy offer a viable approach to reconstructing neural circuits for individuals suffering from stroke or traumatic brain injuries. Successful transplantation relies on effective engraftment and neurite extension from the grafts. Earlier research has validated the effectiveness of delaying the transplantation procedure by 1 week. Here, we hypothesized that brain tissues 1 week following a traumatic brain injury possess a more favorable environment for cell transplantation when compared to immediately after injury. We performed a transcriptomic comparison to differentiate gene expression between these 2 temporal states. In controlled in vitro conditions, recombinant human progranulin (rhPGRN) bolstered the survival rate of dissociated neurons sourced from human induced pluripotent stem cell-derived COs (hiPSC-COs) under conditions of enhanced oxidative stress. This increase in viability was attributable to a reduction in apoptosis via Akt phosphorylation. In addition, rhPGRN pretreatment before in vivo transplantation experiments augmented the engraftment efficiency of hiPSC-COs considerably and facilitated neurite elongation along the host brain's corticospinal tracts. Subsequent histological assessments at 3 months post-transplantation revealed an elevated presence of graft-derived subcerebral projection neurons-crucial elements for reconstituting neural circuits-in the rhPGRN-treated group. These outcomes highlight the potential of PGRN as a neurotrophic factor suitable for incorporation into hiPSC-CO-based cell therapies.

Neurogenic and angiogenic poly(N-acryloylglycine)-co-(acrylamide)-co-(N-acryloyl-glutamate) hydrogel: preconditioning effect under oxidative stress and use in neuroregeneration

Traumatic injuries, neurodegenerative diseases and oxidative stress serve as the early biomarkers for neuronal damage and impede angiogenesis and subsequently neuronal growth. Considering this, the present work aimed to develop a poly(N-acryloylglycine)-co-(acrylamide)-co-(N-acryloylglutamate) hydrogel [p(NAG-Ac-NAE)] with angiogenesis/neurogenesis properties. As constituents of this polymer modulate their vital role in biological functions, inhibitory neurotransmitter glycine regulates neuronal homeostasis, and glutamatergic signalling regulates angiogenesis. The p(NAG-Ac-NAE) hydrogel is a highly branched, biodegradable and pH-responsive polymer with a very high swelling behavior of 6188%. The mechanical stability (G', 2.3-2.7 kPa) of this polymeric hydrogel is commendable in the differentiation of mature neurons. This hydrogel is biocompatible (as tested in HUVEC cells) and helps to proliferate PC12 cells (152.7 ± 13.7%), whereas it is cytotoxic towards aggressive cancers such as glioblastoma (LN229 cells) and triple negative breast cancer (TNBC; MDA-MB-231 cells) and helps to maintain the healthy cytoskeleton framework structure of primary cortical neurons by facilitating the elongation of the axonal pathway. Furthermore, FACS results revealed that the synthesized hydrogel potentiates neurogenesis by inducing the cell cycle (G0/G1) and arresting the sub-G1 phase by limiting apoptosis. Additionally, RT-PCR results revealed that this hydrogel induced an increased level of HIF-1α expression, providing preconditioning effects towards neuronal cells under oxidative stress by scavenging ROS and initiating neurogenic and angiogenic signalling. This hydrogel further exhibits more pro-angiogenic activities by increasing the expression of VEGF isoforms compared to previously reported hydrogels. In conclusion, the newly synthesized p(NAG-Ac-NAE) hydrogel can be one of the potential neuroregenerative materials for vasculogenesis-assisted neurogenic applications and paramount for the management of neurodegenerative diseases.

Anti-skin ageing activities of rice (Oryza sativa) bran soft and hard waxes in cultured skin cells

OBJECTIVE

Rice (Oryza sativa) bran waxes, the by-products of rice bran oil manufacturing, are widely used as inactive components in several preparations. Nevertheless, the function of rice bran waxes against skin ageing has never been reported. This study aimed to investigate thermal property and fatty acid profile of rice bran waxes, including rice bran soft (RBS) and hard (RBH) waxes, and the activities against skin ageing in cultured skin cells.

METHODS

Thermal property and fatty acid profile of rice bran waxes were analysed by differential scanning calorimetry and gas chromatography-mass spectrometry, respectively. The cytotoxicity assay of waxes was performed in B16F10 melanoma cells, human skin fibroblasts and co-culture cells of HaCaT cells and human skin fibroblasts. The non-cytotoxic concentrations of waxes were evaluated for their activities against skin ageing, including melanogenesis assay, antioxidant activity, collagen content analysis, matrix metalloproteinase-1 and matrix metalloproteinase-2 inhibitory assay and anti-inflammatory activity.

RESULTS

Thermal property indicated the endotherm peaks with melting temperatures at 40.89 ± 0.27°C and 69.64 ± 0.34°C for RBS and RBH, respectively. The main fatty acids in RBS were oleic (31.68 ± 0.75%) and linoleic acids (27.19 ± 0.40%), whereas those in RBH were palmitic (36.24 ± 1.08%) and stearic acids (35.21 ± 4.51%). The cytotoxicity assay in single cells and co-culture cells showed the non-cytotoxicity of RBS (0.0001-1 mg/mL) and RBH (0.0001-0.1 mg/mL). The anti-skin ageing activities of 1 mg/mL RBS and 0.1 mg/mL RBH included the melanogenesis inhibition by suppression of tyrosinase and tyrosinase-related protein-2 enzymes, the antioxidant activity by cellular protection against cell damage and cell death, the collagen stimulation, the matrix metalloproteinase-1 and matrix metalloproteinase-2 suppression and the anti-inflammation.

CONCLUSIONS

The study results suggest that RBS and RBH can potentially be applied as the functional ingredients in formulations against skin ageing as well as provide the superior benefit on skin moisturization.

Neuroprotective effects of hesperetin on H2O2-induced damage in neuroblastoma SH-SY5Y cells

BACKGROUND/OBJECTIVES

Oxidative stress is a fundamental neurodegenerative disease trigger that damages and decimates nerve cells. Neurodegenerative diseases are chronic central nervous system disorders that progress and result from neuronal degradation and loss. Recent studies have extensively focused on neurodegenerative disease treatment and prevention using dietary compounds. Heseperetin is an aglycone hesperidin form with various physiological activities, such as anti-inflammation, antioxidant, and antitumor. However, few studies have considered hesperetin's neuroprotective effects and mechanisms; thus, our study investigated this in hydrogen peroxide (H2O2)-treated SH-SY5Y cells.

MATERIALS/METHODS

SH-SY5Y cells were treated with H2O2 (400 µM) in hesperetin absence or presence (10-40 µM) for 24 h. Three-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assays detected cell viability, and 4',6-diamidino-2-phenylindole staining allowed us to observe nuclear morphology changes such as chromatin condensation and apoptotic nuclei. Reactive oxygen species (ROS) detection assays measured intracellular ROS production; Griess reaction assays assessed nitric oxide (NO) production. Western blotting and quantitative polymerase chain reactions quantified corresponding mRNA and proteins.

RESULTS

Subsequent experiments utilized various non-toxic hesperetin concentrations, establishing that hesperetin notably decreased intracellular ROS and NO production in H2O2-treated SH-SY5Y cells (P < 0.05). Furthermore, hesperetin inhibited H2O2-induced inflammation-related gene expression, including interluekin-6, tumor necrosis factor-α, and nuclear factor kappa B (NF-κB) p65 activation. In addition, hesperetin inhibited NF-κB translocation into H2O2-treated SH-SY5Y cell nuclei and suppressed mitogen-activated protein kinase protein expression, an essential apoptotic cell death regulator. Various apoptosis hallmarks, including shrinkage and nuclear condensation in H2O2-treated cells, were suppressed dose-dependently. Additionally, hesperetin treatment down-regulated Bax/Bcl-2 expression ratios and activated AMP-activated protein kinase-mammalian target of rapamycin autophagy pathways.

CONCLUSION

These results substantiate that hesperetin activates autophagy and inhibits apoptosis and inflammation. Hesperetin is a potentially potent dietary agent that reduces neurodegenerative disease onset, progression, and prevention.

Neuroprotective Effects of Zerumbone on H2O2-Induced Oxidative Injury in Human Neuroblastoma SH-SY5Y Cells

Oxidative stress is recognized as one of the main reasons for cellular damage and neurodegenerative diseases. Zerumbone is one of the sesquiterpenoid compounds in the essential oil of Zingiber zerumbet Smith. Zerumbone exhibits various physiological activities, such as anticancer, antioxidant, and antibacterial effects. However, studies on the neuroprotective efficacy of zerumbone and the mechanism behind it are lacking. In this study, we explored the neuroprotective efficacy of zerumbone and its mechanism in hydrogen peroxide-treated human neuroblastoma SH-SY5Y cells. H2O2 treatment (400 μM) for 24 h enhanced the generation of intracellular reactive oxygen species (ROS) compared to untreated cells. By contrast, zerumbone treatment significantly suppressed the production of intracellular ROS. Zerumbone significantly inhibited H2O2-induced nitric oxide production and expression of inflammation-related genes. Moreover, zerumbone decreased H2O2-induced mitogen-activated protein kinase (MAPK) protein expression. Various hallmarks of apoptosis in H2O2-treated cells were suppressed in a dose-dependent manner through downregulation of the Bax/Bcl-2 expression ratio by zerumbone. Since activation of AMP-activated kinase (AMPK) is a promising therapeutic target for neurodegenerative diseases, we also investigated the mammalian target of rapamycin (mTOR) as part of the autophagy mechanism in H2O2-treated SH-SY5Y cells. In this study, zerumbone upregulated the expression of Sirtuin 1 (SIRT1) and p-AMPK (which were downregulated by the H2O2 treatment) and downregulated p-mTOR. Altogether, our results propose that inhibition of apoptosis and inflammation by autophagy activation plays an important neuroprotective role in H2O2-treated SH-SY5Y cells. Zerumbone may thus be a potent dietary agent that reduces the onset and progression, as well as prevents neurodegenerative diseases.

Kynurenine monooxygenase regulates inflammation during critical illness and recovery in experimental acute pancreatitis

Kynurenine monooxygenase (KMO) blockade protects against multiple organ failure caused by acute pancreatitis (AP), but the link between KMO and systemic inflammation has eluded discovery until now. Here, we show that the KMO product 3-hydroxykynurenine primes innate immune signaling to exacerbate systemic inflammation during experimental AP. We find a tissue-specific role for KMO, where mice lacking Kmo solely in hepatocytes have elevated plasma 3-hydroxykynurenine levels that prime inflammatory gene transcription. 3-Hydroxykynurenine synergizes with interleukin-1β to cause cellular apoptosis. Critically, mice with elevated 3-hydroxykynurenine succumb fatally earlier and more readily to experimental AP. Therapeutically, blockade with the highly selective KMO inhibitor GSK898 rescues the phenotype, reducing 3-hydroxykynurenine and protecting against critical illness and death. Together, our findings establish KMO and 3-hydroxykynurenine as regulators of inflammation and the innate immune response to sterile inflammation. During critical illness, excess morbidity and death from multiple organ failure can be rescued by systemic KMO blockade.

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

In the cosmetic and pharmaceutical industries, it has been increasingly popular to use alternative solvents in the extraction of bioactive compounds from plants. Coffee pulp, a by-product of coffee production, contains different phenolic compounds with antioxidant properties. The effects of polyols, amplitude, extraction time, solvent concentration, and liquid-solid ratio on total phenolic content (TPC) using ultrasound-assisted extraction (UAE) were examined by single-factor studies. Three main factors that impact TPC were selected to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and their antioxidant activities using the Box-Behnken design. Different extraction methods were compared, the bioactive compounds were identified and quantified by liquid chromatography triple quadrupole mass spectrometer (LC-QQQ), and the cytotoxicity and cellular antioxidant activities of the extract were studied. According to the response model, the optimal conditions for the extraction of antioxidants from coffee pulp were as follows: extraction time of 7.65 min, liquid-solid ratio of 22.22 mL/g, and solvent concentration of 46.71 %. Under optimized conditions, the values of TPC, TFC, TTC, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay, and Ferric reducing antioxidant power assay (FRAP) were 9.29 ± 0.02 mg GAE/g sample, 58.82 ± 1.38 mg QE/g sample, 8.69 ± 0.25 mg TAE/g sample, 7.56 ± 0.27 mg TEAC/g sample, 13.59 ± 0.25 mg TEAC/g sample, and 10.90 ± 0.24 mg FeSO₄/g sample, respectively. Compared with other extraction conditions, UAE with propylene glycol extract (PG-UAE) was significantlyhigher in TPC, TFC, TTC, DPPH, ABTS, and FRAP response values than UAE with ethanol (EtOH-UAE), maceration with propylene glycol (PG-maceration), and maceration with ethanol (EtOH -maceration) (p < 0.05). Major bioactive compounds detected by LC-QQQ included chlorogenic acid, caffeine, and trigonelline. At higher concentrations starting from 5 mg/ml, PG-UAE extract showed higher cell viability than EtOH-UAE in both cytotoxicity and cellular antioxidant assays. The researcher expects that this new extraction technique developed in this work could produce a higher yield of bioactive compounds with higher biological activity. Therefore, they can be used as active ingredients in cosmetics (anti-aging products) and pharmaceutical applications (food supplements, treatment for oxidative stress-related diseases) with minimal use of chemicals and energy.

Pridopidine Promotes Synaptogenesis and Reduces Spatial Memory Deficits in the Alzheimer's Disease APP/PS1 Mouse Model

Sigma-1 receptor agonists have recently gained a great deal of interest due to their anti-amnesic, neuroprotective, and neurorestorative properties. Compounds such as PRE-084 or pridopidine (ACR16) are being studied as a potential treatment against cognitive decline associated with neurodegenerative disease, also to include Alzheimer's disease. Here, we performed in vitro experiments using primary neuronal cell cultures from rats to evaluate the abilities of ACR16 and PRE-084 to induce new synapses and spines formation, analyzing the expression of the possible genes and proteins involved. We additionally examined their neuroprotective properties against neuronal death mediated by oxidative stress and excitotoxicity. Both ACR16 and PRE-084 exhibited a concentration-dependent neuroprotective effect against NMDA- and H2O2-related toxicity, in addition to promoting the formation of new synapses and dendritic spines. However, only ACR16 generated dendritic spines involved in new synapse establishment, maintaining a more expanded activation of MAPK/ERK and PI3K/Akt signaling cascades. Consequently, ACR16 was also evaluated in vivo, and a dose of 1.5 mg/kg/day was administered intraperitoneally in APP/PS1 mice before performing the Morris water maze. ACR16 diminished the spatial learning and memory deficits observed in APP/PS1 transgenic mice via PI3K/Akt pathway activation. These data point to ACR16 as a pharmacological tool to prevent synapse loss and memory deficits associated with Alzheimer's disease, due to its neuroprotective properties against oxidative stress and excitotoxicity, as well as the promotion of new synapses and spines through a mechanism that involves AKT and ERK signaling pathways.

The Antibody Dependant Neurite Outgrowth Modulation Response Involvement in Spinal Cord Injury

Spinal cord injury (SCI) represents a major medical challenge. At present, there is still no cure to treat it efficiently and enable functional recovery below the injury site. Previously, we demonstrated that inflammation determines the fate of the physiopathology. To decipher the molecular mechanisms involved in this process, we performed a meta-analysis of our spatio-temporal proteomic studies in the time course of SCI. This highlighted the presence of IgG isotypes in both spinal cord explants and their secretomes. These IgGs were detected in the spinal cord even if no SCI occurred. However, during the time course following SCI, abundance of IgG1 and IgG2 subclasses (a, b, c) varied according to the spatial repartition. IgG1 was clearly mostly abundant at 12 h, and a switch to IgG2a was observed after 24 h. This IgG stayed predominant 3, 7, and 10 days after SCI. A protein related to IgM as well as a variable heavy chain were only detected 12 h after lesion. Interestingly, treatment with RhoA inhibitor influenced the abundance of the various IgG isotypes and a preferential switch to IgG2c was observed. By data reuse of rat dorsal root ganglion (DRG) neurons RNAseq datasets and RT-PCR experiments performed on cDNA from DRG sensory neurons ND7/23 and N27 dopaminergic neural cell lines, we confirmed expression of immunoglobulin heavy and light chains (constant and variable) encoding genes in neurons. We then identified CD16 and CD32b as their specific receptors in sensory neuron cell line ND7/23 and their activation regulated neurites outgrowth. These results suggest that during SCI, neuronal IgG isotypes are released to modulate neurites outgrowth. Therefore, we propose a new view of the SCI response involving an antibody dependent neurite outgrowth modulation (ADNM) which could be a precursor to the neuroinflammatory response in pathological conditions.

A non-enzymatic electrochemical hydrogen peroxide sensor based on copper oxide nanostructures

This article describes the synthesis of nanostructured copper oxide on copper wires and its application for the detection of hydrogen peroxide. Copper oxide petal nanostructures were obtained by a one-step hydrothermal oxidation method. The resulting coating is uniform and dense and shows good adhesion to the wire surface. Structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resulting nanostructured samples were used for electrochemical determination of the H2O2 content in a 0.1 M NaOH buffer solution using cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A good linear relationship between the peak current and the concentration of H2O2 in the range from 10 to 1800 μM was obtained. The sensitivity of the obtained CuO electrode is 439.19 μA·mM-1. The calculated limit of detection is 1.34 μM, assuming a signal-to-noise ratio of 3. The investigation of the system for sensitivity to interference showed that the most common interfering substances, that is, ascorbic acid, uric acid, dopamine, NaCl, glucose, and acetaminophen, do not affect the electrochemical response. The real milk sample test showed a high recovery rate (more than 95%). According to the obtained results, this sensor is suitable for practical use for the qualitative detection of H2O2 in real samples, as well as for the quantitative determination of its concentration.

Inhibiting BDNF Signaling Upregulates Hippocampal H3K9me3 in a Manner Dependent On In Vitro Aging and Oxidative Stress

Histone modifications are key contributors to the cognitive decline that occurs in aging and Alzheimer's disease. Our lab has previously shown that elevated H3K9me3 in aged mice is correlated with synaptic loss, cognitive impairment and a reduction in brain derived neurotrophic factor (BDNF). However, the mechanism of H3K9me3 regulation remains poorly understood. In this study, we investigated the role of age-associated stressors on H3K9me3 regulation and examined if changes in H3K9me3 were age dependent. We used cultured hippocampal neurons at 6, 12, and 21 days in vitro (DIV) to examine the effect of different stressors on H3K9me3 across neuron ages. We found that the oxidative stressor hydrogen peroxide (H2O2) does not induce H3K9me3 in 12 DIV neurons. Inhibiting BDNF signaling via TrkB-Fc elevated H3K9me3 in 12 and 21 DIV neurons compared to 6 DIV neurons. Antioxidant treatment prevented H3K9me3 elevation in 12 DIV neurons treated with TrkB-Fc and H2O2. H2O2 elevated the epigenetic regulator SIRT1 in 6 DIV neurons but did not increase H3K9me3 levels. Our findings demonstrate that inhibiting BDNF signaling elevates hippocampal H3K9me3 in a manner dependent on in vitro age and oxidative stress.

Neuroprotective and anxiolytic potential of green rooibos (Aspalathus linearis) polyphenolic extract

South African rooibos (Aspalathus linearis) tea is globally consumed for its health benefits and caffeine free nature, but no information is available on the neuroprotective capacity of (unfermented) green rooibos. Our aim was to investigate the cytoprotective activity of green rooibos in neuronal cells, including probing antioxidant and enzyme inhibitory properties that could explain observed effects in these cells. We also investigated the anxiolytic potential of green rooibos using zebrafish larval models. Green rooibos extract (Green oxithin™) was assessed for its neuroprotective potential in Neuro-2a cells treated with different concentrations of the extract (12.5-25-50-100 μg mL^-1) and different concentrations of hydrogen peroxide (250 or 125 μM) as oxidizing agent. Cell viability (MTT) and redox status (intracellular ROS) were also quantified in these cells. Antioxidant properties of the extract were quantified using cell-free systems (DPPH, ORAC and xanthine/xanthine oxidase), and potential neuroprotection evaluated in terms of its potential to inhibit key enzymes of the CNS (monoamine oxidase A (MOA-A), acetylcholinesterase (AChE) and tyrosinase (TYR)). Results demonstrated that green rooibos extract exerted significant cytoprotective properties in Neuro-2a cells, particularly when exposed to lethal 250 μM hydrogen peroxide, increasing cell survival by more than 100%. This may be ascribed (at least partially) to its capacity to limit intracellular ROS accumulation in these cells. Data from cell-free systems confirmed that green rooibos was able to scavenge free radicals (synthetic and physiological) in a dose dependent manner with a similar profile activity to vitamins C and E. Green rooibos also acted as a moderate MAO-A inhibitor, but had no significant effect on AChE or TYR. Finally, zebrafish larvae treated with lower doses of green rooibos demonstrated a significant anxiolytic effect in the light-dark anxiety model. Using the PTZ excitotoxicity model, green rooibos was shown to rescue GABA receptor signalling, which together with its demonstrated inhibition of MAO-A, may account for the anxiolytic outcome. Current data confirms that green rooibos could be considered a "functional brain food" and may be a good option as starting ingredient in the development of new nutraceuticals.

Induction of Apoptotic Cell Death by Oral Streptococci in Human Periodontal Ligament Cells

Initiation and progression of oral infectious diseases are associated with streptococcal species. Bacterial infection induces inflammatory responses together with reactive oxygen species (ROS), often causing cell death and tissue damage in the host. In the present study, we investigated the effects of oral streptococci on cytotoxicity and ROS production in human periodontal ligament (PDL) cells. Streptococcus gordonii showed cell cytotoxicity in a dose- and time-dependent manner. The cytotoxicity might be due to apoptosis since S. gordonii increased annexin V-positive cells, and the cytotoxicity was reduced by an apoptosis inhibitor, Z-VAD-FMK. Other oral streptococci such as Streptococcus mitis, Streptococcus sanguinis, and Streptococcus sobrinus also induced apoptosis, whereas Streptococcus mutans did not. All streptococci tested except S. mutans triggered ROS production in human PDL cells. Interestingly, however, streptococci-induced apoptosis appears to be ROS-independent, as the cell death induced by S. gordonii was not recovered by the ROS inhibitor, resveratrol or n-acetylcysteine. Instead, hydrogen peroxide (H₂O₂) appears to be important for the cytotoxic effects of streptococci since most oral streptococci except S. mutans generated H₂O₂, and the cytotoxicity was dramatically reduced by catalase. Furthermore, streptococcal lipoproteins are involved in cytotoxicity, as we observed that cytotoxicity induced by the lipoprotein-deficient S. gordonii mutant was less potent than that by the wild-type and was attenuated by anti-TLR2-neutralizing antibody. Indeed, lipoproteins purified from S. gordonii alone were sufficient to induce cytotoxicity. Notably, S. gordonii lipoproteins did not induce H₂O₂ or ROS but cooperatively induced cell death when co-treated with H₂O₂. Taken together, these results suggest that most oral streptococci except S. mutans efficiently induce damage to human PDL cells by inducing apoptotic cell death with bacterial H₂O₂ and lipoproteins, which might contribute to the progression of oral infectious diseases such as apical periodontitis.

Hydrolase-Treated Royal Jelly Attenuates H2O2- and Glutamate-Induced SH-SY5Y Cell Damage and Promotes Cognitive Enhancement in a Rat Model of Vascular Dementia

Vascular dementia (VaD) is the second most common type of dementia following Alzheimer's disease, but the therapeutic efficacy is still not effective. This makes the searching for novel neuroprotective agents important. Therefore, we hypothesized that royal jelly, a well-known traditional medicine, could attenuate memory impairment and brain damage in vascular dementia. This study determined the effects of royal jelly hydrolysate (RJH) and possible mechanism of cell damage and cognitive-enhancing effect in animal study. An in vitro study assessed the effects of RJH on acetylcholinesterase inhibitor, cell viability, and cell damage in SH-SY5Y neuroblastoma cells. Then, an in vivo study examined vascular dementia by the occlusion of the right middle cerebral artery (Rt.MCAO); adult male Wistar rats had been orally given RJH at doses ranging from 10, 50, to 100 mg/kg for 14 days before and 14 days after the occlusion of Rt.MCAO to mimic the VaD condition. Rats' spatial memory was evaluated using Morris water maze and radial arm maze every 7 days after Rt.MCAO throughout a 14-day experimental period, and then, they were sacrificed and the acetylcholinesterase (AChE) activity in the hippocampus was determined. The results showed that RJH has no cytotoxic effect with the final concentration up to 500 μg protein/ml and reduces cell death from the H₂O₂- and glutamate-induced cell damage in in vitro neuroblastoma cells. Importantly, RJH significantly improved memory performance in Morris water maze test and radial arm maze and decreased the level of acetyl cholinesterase activity. In conclusion, RJH is the potential neuroprotective agent and cognitive enhancer for VaD.

Phyllanthus emblica L. (amla) branch: A safe and effective ingredient against skin aging

BACKGROUND AND AIM

Skin aging influences the changes in skin, including skin dryness, wrinkle, and irregular pigmentation. Amla (Phyllanthus emblica L.) branch has shown several benefits, but not the anti-skin aging. The study aimed to evaluate the anti-skin aging efficacy of amla branch.

EXPERIMENTAL PROCEDURE

Amla branches were standardized the phenolic acids. The extract was investigated anti-skin aging activities, including antioxidant, anti-tyrosinase, anti-melanogenesis, and matrix metalloproteinase-2 inhibitory assays. Topical gel containing extract was prepared and evaluated the skin irritation by a single closed patch test. Randomized, double-blind, placebo-control study was performed in 20 volunteers for 84 consecutive days. The tested skin was evaluated by Chromameter® CR 400, Dermalab® USB, Mexameter® MX 18, Corneometer® CM 825, and Visioscan® VC 98.

RESULTS

Amla branch extract, a dark brown powder, consisted a variety of phenolic acids, mainly sinapic and ferulic acids. The extract exhibited the potent antioxidant and tyrosinase inhibitory activities in vitro assays and the melanin suppression through inhibition of tyrosinase and tyrosinase-related protein-2 activities, the strong antioxidant, and the potent matrix metalloproteinase-2 in cellular assays at 0.1 mg/mL. Topical gel containing 0.1% extract was a stable and safe formulation. Clinical study was proved the superior anti-skin aging efficacy, including the lightening skin color, the enhanced skin elasticity and hydration, and the skin wrinkle reduction.

CONCLUSION

The study results suggested that amla branch is a rich source of bioactive compounds and can be a potential ingredient for utilization in anti-skin aging products.

Polychlorinated biphenyls induce oxidative stress and metabolic responses in astrocytes

Exposure to environmental toxicants is prevalent, hazardous and linked to varied detrimental health outcomes and disease. Polychlorinated biphenyls (PCBs), a class of hazardous organic chlorines once widely used for industrial purposes, are associated with neurodegenerative disease and oxidative stress in both in vitro and in vivo models. Here, we investigated the impact of Aroclor 1254, a commercially available PCB mixture, on primary murine astrocytes to determine the response to this once ubiquitously used toxicant on the most numerous cells of the central nervous system (CNS). Astrocytes are a critical component of homeostasis throughout the CNS, including at the blood-brain barrier, where they serve as the primary defense against xenobiotics entering the CNS, and at the synapse, where they are closely coupled to neurons through several metabolic pathways. We hypothesized that PCBs cause astrocytic oxidative stress and related dysfunction including altered metabolism. We exposed primary murine cortical astrocytes to PCBs and report an increased expression of antioxidant genes (Prdx1, Gsta2, Gfap, Amigo2) in response to oxidative stress. Our data show increased ATP production and spare respiratory capacity in astrocytes exposed to 10 μM (∼ 3 ppm) PCBs. This dose also causes an increase in glucose uptake that is not seen at a higher dose (50 μM) suggesting that, at a lower dose, astrocytes are able to engage compensatory mechanisms to promote survival. Together, these data suggest that exposure to PCBs impact astrocytic metabolism, which is important to consider both in the context of human health and disease and in in vitro and in vivo disease models.

Tetrandrine Enhances H2O2-Induced Apoptotic Cell Death Through Caspase-dependent Pathway in Human Keratinocytes

BACKGROUND

Tetrandrine, a bis-benzylisoquinoline alkaloid, induces apoptosis of many types of human cancer cell. Hydrogen peroxide (H₂O₂) is a reactive oxygen species inducer; however, there are no reports to show whether pre-treatment of tetrandrine with H₂O₂ induces more cell apoptosis than H₂O₂ alone. Thus, the present study investigated the effects of tetrandrine on H₂O₂-induced cell apoptosis of human keratinocytes, HaCaT, in vitro.

MATERIALS AND METHODS

HaCaT cells were pre-treated with and without tetrandrine for 1 h, and then treated with H₂O₂ for examining cell morphological changes and cell viability using contrast-phase microscopy and propidium iodide (PI) exclusion assay, respectively. Cells were measured apoptotic cell death by using annexin V/PI double staining and further analyzed by flow cytometer. Cells were further assessed for DNA condensation using 2-(4-amidinophenyl)-6-indolecarbamidine staining. Western blotting was used to measure expression of apoptosis-associated proteins and confocal laser microscopy was used to measure the protein expression and nuclear translocation from the cytoplasm to nuclei.

RESULTS

Pre-treatment of tetrandrine for 1 h and treatment with H₂O₂ enhanced H₂O₂-induced cell morphological changes and reduced cell viability, whilst increasing apoptotic cell death and DNA condensation. Furthermore, tetrandrine significantly increased expression of reactive oxygen species-associated proteins such as superoxide dismutase (Cu/Zn) and superoxide dismutase (Mn) but significantly reduced the level of catalase, which was also confirmed by confocal laser microscopy. It also increased expression of DNA repair-associated proteins ataxia telangiectasia mutated, ataxia-telangectasia and Rad3-related, phospho-P53, P53 and phosphorylated histone H2AX, and of pro-apoptotic proteins BCL2 apoptosis regulator-associated X-protein, caspase-3, caspase-8, caspase-9 and poly ADP ribose polymerase in HaCaT cells.

CONCLUSION

These are the first and novel findings showing tetrandrine enhances H₂O₂-induced apoptotic cell death of HaCaT cells and may provide a potent approach for the treatment of proliferated malignant keratinocytes.

A Highly Selective In Vitro JNK3 Inhibitor, FMU200, Restores Mitochondrial Membrane Potential and Reduces Oxidative Stress and Apoptosis in SH-SY5Y Cells

Current treatments for neurodegenerative diseases (ND) are symptomatic and do not affect disease progression. Slowing this progression remains a crucial unmet need for patients and their families. c-Jun N-terminal kinase 3 (JNK3) are related to several ND hallmarks including apoptosis, oxidative stress, excitotoxicity, mitochondrial dysfunction, and neuroinflammation. JNK inhibitors can play an important role in addressing neuroprotection. This research aims to evaluate the neuroprotective, anti-inflammatory, and antioxidant effects of a synthetic compound (FMU200) with known JNK3 inhibitory activity in SH-SY5Y and RAW264.7 cell lines. SH-SY5Y cells were pretreated with FMU200 and cell damage was induced by 6-hydroxydopamine (6-OHDA) or hydrogen peroxide (H₂O₂). Cell viability and neuroprotective effect were assessed with an MTT assay. Flow cytometric analysis was performed to evaluate cell apoptosis. The H₂O₂-induced reactive oxygen species (ROS) generation and mitochondrial membrane potential (ΔΨm) were evaluated by DCFDA and JC-1 assays, respectively. The anti-inflammatory effect was determined in LPS-induced RAW264.7 cells by ELISA assay. In undifferentiated SH-SY5Y cells, FMU200 decreased neurotoxicity induced by 6-OHDA in approximately 20%. In RA-differentiated cells, FMU200 diminished cell death in approximately 40% and 90% after 24 and 48 h treatment, respectively. FMU200 reduced both early and late apoptotic cells, decreased ROS levels, restored mitochondrial membrane potential, and downregulated JNK phosphorylation after H₂O₂ exposure. In LPS-stimulated RAW264.7 cells, FMU200 reduced TNF-α levels after a 3 h treatment. FMU200 protects neuroblastoma SH-SY5Y cells against 6-OHDA- and H₂O₂-induced apoptosis, which may result from suppressing the JNK pathways. Our findings show that FMU200 can be a useful candidate for the treatment of neurodegenerative disorders.

Neuromodulation of BAG co-chaperones by HIV-1 viral proteins and H2O2: implications for HIV-associated neurological disorders

Despite increasing numbers of aged individuals living with HIV, the mechanisms underlying HIV-associated neurological disorders (HANDs) remain elusive. As HIV-1 pathogenesis and aging are characterized by oxidative stress as well as altered protein quality control (PQC), reactive oxygen species (ROS) themselves might constitute a molecular mediator of neuronal PQC by modulating BCL-2 associated athanogene (BAG) family members. Present results reveal H2O2 replicated and exacerbated a reduction in neuronal BAG3 induced by the expression of HIV-1 viral proteins (i.e., Tat and Nef), while also causing an upregulation of BAG1. Such a reciprocal regulation of BAG3 and BAG1 levels was also indicated in two animal models of HIV, the doxycycline-inducible Tat (iTat) and the Tg26 mouse. Inhibiting oxidative stress via antioxidants in primary culture was capable of partially preserving neuronal BAG3 levels as well as electrophysiological functioning otherwise altered by HIV-1 viral proteins. Current findings indicate HIV-1 viral proteins and H2O2 may mediate neuronal PQC by exerting synergistic effects on complementary BAG family members, and suggest novel therapeutic targets for the aging HIV-1 population.

Neuroprotective Effect of Cannabidiol Against Hydrogen Peroxide in Hippocampal Neuron Culture

Introduction: Reports on the neurotoxic and neuroprotective effects of cannabidiol (CBD) have not been in complete accord, showing different and somewhat contradictory results depending upon the brain cell types and experimental conditions employed. This work systematically examines the neuroprotective capability of CBD against oxidative stress (i.e., hydrogen peroxide [H2O2]) as well as its toxicity profile in the in vitro culture platform of primary hippocampal neurons. Materials and Methods: The low cell-density (100 neurons per mm2) culture was used for analyzing the viability and morphology of neurons at a single-cell level with a confocal laser-scanning microscope (CLSM). Primary neurons were obtained from the hippocampal tissues of embryonic day-18 (E18) Sprague-Dawley rat pups and treated with CBD (0.1-100 μM) and/or H2O2 (0.1-50 μM) at 1 DIV (days in vitro). Results: The lethal concentration 50 (LC50) value (the concentration causing 50% cell death) of CBD was calculated to be 9.85 μM after 24 h of incubation, and that of H2O2 was 2.46 μM under the same conditions. The neuroprotection ratio of CBD against H2O2 ([H2O2]=10 μM) was 2.40 with 5 μM of CBD, increasing the cell viability to 57% from 24%. The CLSM analysis suggested that the cell-death mechanisms were different for CBD and H2O2, and CBD did not completely rescue the morphological alterations of primary hippocampal neurons caused by H2O2, such as neurite degeneration, at least in the in vitro neuron culture. Conclusion: Although CBD showed both neurotoxic and neuroprotective effects on hippocampal neurons in the in vitro setting, the use of low-concentrated (i.e., 5 μM) CBD, not causing toxic effects on the neurons, significantly rescued the neurons from the oxidative stress (H2O2), confirming its neuroprotection capability.

A growth-factor-activated lysosomal K+ channel regulates Parkinson's pathology

Lysosomes have fundamental physiological roles and have previously been implicated in Parkinson's disease^1-5. However, how extracellular growth factors communicate with intracellular organelles to control lysosomal function is not well understood. Here we report a lysosomal K⁺ channel complex that is activated by growth factors and gated by protein kinase B (AKT) that we term lysoK_GF. LysoK_GF consists of a pore-forming protein TMEM175 and AKT: TMEM175 is opened by conformational changes in, but not the catalytic activity of, AKT. The minor allele at rs34311866, a common variant in TMEM175, is associated with an increased risk of developing Parkinson's disease and reduces channel currents. Reduction in lysoK_GF function predisposes neurons to stress-induced damage and accelerates the accumulation of pathological α-synuclein. By contrast, the minor allele at rs3488217-another common variant of TMEM175, which is associated with a decreased risk of developing Parkinson's disease-produces a gain-of-function in lysoK_GF during cell starvation, and enables neuronal resistance to damage. Deficiency in TMEM175 leads to a loss of dopaminergic neurons and impairment in motor function in mice, and a TMEM175 loss-of-function variant is nominally associated with accelerated rates of cognitive and motor decline in humans with Parkinson's disease. Together, our studies uncover a pathway by which extracellular growth factors regulate intracellular organelle function, and establish a targetable mechanism by which common variants of TMEM175 confer risk for Parkinson's disease.

Differential regulation of mitochondrial complex I and oxidative stress based on metastatic potential of colorectal cancer cells

Mitochondria serve a vital role in cellular homeostasis as they regulate cell proliferation and death pathways, which are attributed to mitochondrial bioenergetics, free radicals and metabolism. Alterations in mitochondrial functions have been reported in various diseases, including cancer. Colorectal cancer (CRC) is one of the most common metastatic cancer types with high mortality rates. Although mitochondrial oxidative stress has been associated with CRC, its specific mechanism and contribution to metastatic progression remain poorly understood. Therefore, the aims of the present study were to investigate the role of mitochondria in CRC cells with low and high metastatic potential and to evaluate the contribution of mitochondrial respiratory chain (RC) complexes in oncogenic signaling pathways. The present results demonstrated that cell lines with low metastatic potential were resistant to mitochondrial complex I (C-I)-mediated oxidative stress, and had C-I inhibition with impaired mitochondrial functions. These adaptations enabled cells to cope with higher oxidative stress. Conversely, cells with high metastatic potential demonstrated functional C-I with improved mitochondrial function due to coordinated upregulation of mitochondrial biogenesis and metabolic reprogramming. Pharmacological inhibition of C-I in high metastatic cells resulted in increased sensitivity to cell death and decreased metastatic signaling. The present findings identified the differential regulation of mitochondrial functions in CRC cells, based on CRC metastatic potential. Specifically, it was suggested that a functional C-I is required for high metastatic features of cancer cells, and the role of C-I could be further examined as a potential target in the development of novel therapies for diagnosing high metastatic cancer types.

Intratumoral Hydrogen Peroxide With Radiation Therapy in Locally Advanced Breast Cancer: Results From a Phase 1 Clinical Trial

PURPOSE

Hydrogen peroxide (H2O2) plays a vital role in normal cellular processes but at supraphysiological concentrations causes oxidative stress and cytotoxicity, a property that is potentially exploitable for the treatment of cancer in combination with radiation therapy (RT). We report the first phase 1 trial testing the safety and tolerability of intratumoral H2O2 + external beam RT as a novel combination in patients with breast cancer and exploratory plasma marker analyses investigating possible mechanisms of action.

METHODS AND MATERIALS

Twelve patients with breast tumors ≥3 cm (surgically or medically inoperable) received intratumoral H2O2 with either 36 Gy in 6 twice-weekly fractions (n = 6) or 49.5 Gy in 18 daily fractions (n = 6) to the whole breast ± locoregional lymph nodes in a single-center, nonrandomized study. H2O2 was mixed in 1% sodium hyaluronate gel (final H2O2 concentration 0.5%) before administration to slow drug release and minimize local discomfort. The mixture was injected intratumorally under ultrasound guidance twice weekly 1 hour before RT. The primary endpoint was patient-reported maximum intratumoral pain intensity before and 24 hours postinjection. Secondary endpoints included grade ≥3 skin toxicity and tumor response by ultrasound. Blood samples were collected before, during, and at the end of treatment for cell-death and immune marker analysis.

RESULTS

Compliance with H2O2 and RT was 100%. Five of 12 patients reported moderate pain after injection (grade 2 Common Terminology Criteria for Adverse Events v4.02) with median duration 60 minutes (interquartile range, 20-120 minutes). Skin toxicity was comparable to RT alone, with maintained partial/complete tumor response relative to baseline in 11 of 12 patients at last follow-up (median 12 months). Blood marker analysis highlighted significant associations of TRAIL, IL-1β, IL-4, and MIP-1α with tumor response.

CONCLUSIONS

Intratumoral H2O2 with RT is well tolerated with no additional toxicity compared with RT alone. If efficacy is confirmed in a randomized phase 2 trial, the approach has potential as a cost-effective radiation response enhancer in multiple cancer types in which locoregional control after RT alone remains poor.

Multicompartment Microreactors Prevent Excitotoxic Dysfunctions In Rat Primary Cortical Neurons

Excitotoxicity is a cellular phenomenon that comprises the consequences of toxic actions of excitatory neurotransmitters, such as glutamate. This process is usually related to overproduction of reactive oxygen species (ROS) and ammonia (NH₄ ⁺ ) toxicity. Platinum nanoparticle (Pt-NP)-based microreactors able to degrade hydrogen peroxide (H₂ O₂ ) and NH₄ ⁺ , are previously described as a novel therapeutical approach against excitotoxicity, conferring protection to neuroblasts. Now, it is demonstrated that these microreactors are compatible with rat primary cortical neurons, show high levels of neuronal membrane interaction, and are able to improve cell survival and neuronal activity when neurons are exposed to H₂ O₂ or NH₄ ⁺ . Additionally, more complex microreactors are assembled, including enzyme-loaded liposomes containing glutamate dehydrogenase and glutathione reductase, in addition to Pt-NP. The in vitro activity of these microreactors is characterized and they are compared to the Pt-NP-based microreactors in terms of biological activity, concluding that they enhance cell viability similarly or more extensively than the latter. Extracellular electrophysiological recordings demonstrate that these microreactors rescue neuronal functionality lost upon incubation with H₂ O₂ or NH₄ ⁺ . This study provides more evidence for the potential application of these microreactors in a biomedical context with more complex cellular environments.

Hetero-structured MnO-Mn3O4@rGO composites: Synthesis and nonenzymatic detection of H2O2

The construction of metal-oxide heterojunction architecture has greatly widened applications in the fields of optoelectronics, energy conversions and electrochemical sensors. In this study, olive-like hetero-structured MnO-Mn₃O₄ microparticles wrapped by reduced graphene oxide (MnO-Mn₃O₄@rGO) were synthesized through a facile solvothermal-calcination treatment. The morphology and structure of MnO-Mn₃O₄@rGO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction. The as-synthesized MnO-Mn₃O₄@rGO exhibited prominent catalyzing effect on the electroreduction of H₂O₂, due to the combination of good electrical conductivity of rGO and the synergistic effect of MnO and Mn₃O₄. The MnO-Mn₃O₄@rGO modified glassy carbon electrode provided a wide linear response from 0.004 to 17 mM, a low detection limit of 0.1 μM, and high sensitivity of 274.15 μA mM^-1 cm^-2. The proposed sensor displayed noticeable selectivity and long-term stability. In addition, the biosensor has been successfully applied for detecting H₂O₂ in tomato sauce with good recovery, revealing its promising potential applications for practical electrochemical sensors.

A Genome-Wide CRISPR/Cas9 Screen Reveals that Riboflavin Regulates Hydrogen Peroxide Entry into HAP1 Cells

Extracellular hydrogen peroxide can induce oxidative stress, which can cause cell death if unresolved. However, the cellular mediators of H2O2-induced cell death are unknown. We determined that H2O2-induced cytotoxicity is an iron-dependent process in HAP1 cells and conducted a CRISPR/Cas9-based survival screen that identified four genes that mediate H2O2-induced cell death: POR (encoding cytochrome P450 oxidoreductase), RETSAT (retinol saturase), KEAP1 (Kelch-like ECH-associated protein-1), and SLC52A2 (riboflavin transporter). Among these genes, only POR also mediated methyl viologen dichloride hydrate (paraquat)-induced cell death. Because the identification of SLC52A2 as a mediator of H2O2 was both novel and unexpected, we performed additional experiments to characterize the specificity and mechanism of its effect. These experiments showed that paralogs of SLC52A2 with lower riboflavin affinities could not mediate H2O2-induced cell death and that riboflavin depletion protected HAP1 cells from H2O2 toxicity through a specific process that could not be rescued by other flavin compounds. Interestingly, riboflavin mediated cell death specifically by regulating H2O2 entry into HAP1 cells, likely through an aquaporin channel. Our study results reveal the general and specific effectors of iron-dependent H2O2-induced cell death and also show for the first time that a vitamin can regulate membrane transport.IMPORTANCE Using a genetic screen, we discovered that riboflavin controls the entry of hydrogen peroxide into a white blood cell line. To our knowledge, this is the first report of a vitamin playing a role in controlling transport of a small molecule across the cell membrane.

Seaweed Porphyra yezoensis polysaccharides with different molecular weights inhibit hydroxyapatite damage and osteoblast differentiation of A7R5 cells

Vascular calcification (VC) is a common pathological manifestation in patients with cardiovascular diseases, leading to high mortality in patients with chronic kidney diseases. The deposition of hydroxyapatite (HAP) crystals on vascular smooth muscle cells leads to cell damage, which promotes osteogenic transformation. In this study, four different molecular weights (MWs ) of Porphyra yezoensis polysaccharides (PYP1, PYP2, PYP3, and PYP4 with MWs of 576, 49.5, 12.6, and 4.02 kDa, respectively) were used to coat HAP, and the differences in toxicity and calcification of HAP on A7R5 cells before and after coating were studied. The results showed that PYPs could effectively reduce HAP damage to the A7R5 cells. Under the protection of PYPs, cell viability increased and lactate dehydrogenase release, active oxygen level, and cell necrosis rate decreased; also, the amount of the HAP crystals adhering to cell surfaces and entering cells decreased. PYPs with low molecular weights presented better protective effects than high-molecular-weight PYPs. PYPs also inhibited the osteogenic transformation of the A7R5 cells induced by HAP and decreased alkaline phosphatase (ALP) activity and expressions of bone/chondrocyte phenotype genes (runt-related factor 2, ALP, osteopontin, and osteocalcin). In the adenine-induced chronic renal failure (CRF) mouse VC model, PYP4 was found to obviously inhibit the aortic calcium level, and it also inhibited the serum creatinine, serum phosphorus and serum BUN levels. PYP4 (least molecular weight) showed the best inhibitory effect on calcification and may be considered as a candidate drug with therapeutic potential for inhibiting cellular damage and osteoblast differentiation induced by the HAP crystals.

Therapeutic Contact Lens for Scavenging Excessive Reactive Oxygen Species on the Ocular Surface

Excessive reactive oxygen species (ROS) play a significant role in the pathogenesis of many eye diseases. Controlling oxidative stress by reducing the amount of ROS is a potential therapeutic strategy for the prevention and treatment of eye diseases, particularly ocular surface diseases. Ceria nanoparticles (CeNPs) have been investigated owing to their efficient ROS-scavenging properties. To overcome the disadvantages of eyedrop administration due to rapid elimination on the surface of the eye and to retain the intrinsic properties of contact lenses, we developed an ROS-scavenging water-soluble CeNP-embedded contact lens (CeNP-CL) for the prevention of ocular surface diseases. The intrinsic ROS-scavenging property of the CeNPs, which mimicked the activities of superoxide dismutase and catalase, was incorporated into polyhydroxyethyl methacrylate-based contact lenses. The CeNP-CL exhibited high transparency and physical properties comparable to those of a commercial contact lens, along with excellent extracellular ROS-scavenging properties. The viabilities of human conjunctival epithelial cells and human meibomian gland epithelial cells were significantly enhanced in the presence of CeNP-CLs, even in media with high H₂O₂ contents (100 and 500 μM). Additionally, the wearing of CeNP-CLs on the eyes had a protective effect in a mouse model when 3% H₂O₂ eyedrops were administered. These results indicate the salvaging effect of the CeNP-CL in a high-ROS environment on the ocular surface, which may be helpful for the treatment of ocular surface diseases.

Hyperoxidation of mitochondrial peroxiredoxin limits H2 O2 -induced cell death in yeast

Hydrogen peroxide (H2 O2 ) plays important roles in cellular signaling, yet nonetheless is toxic at higher concentrations. Surprisingly, the mechanism(s) of cellular H2 O2 toxicity remain poorly understood. Here, we reveal an important role for mitochondrial 1-Cys peroxiredoxin from budding yeast, Prx1, in regulating H2 O2 -induced cell death. We show that Prx1 efficiently transfers oxidative equivalents from H2 O2 to the mitochondrial glutathione pool. Deletion of PRX1 abrogates glutathione oxidation and leads to a cytosolic adaptive response involving upregulation of the catalase, Ctt1. Both of these effects contribute to improved cell viability following an acute H2 O2 challenge. By replacing PRX1 with natural and engineered peroxiredoxin variants, we could predictably induce widely differing matrix glutathione responses to H2 O2 . Therefore, we demonstrated a key role for matrix glutathione oxidation in driving H2 O2 -induced cell death. Finally, we reveal that hyperoxidation of Prx1 serves as a switch-off mechanism to limit oxidation of matrix glutathione at high H2 O2 concentrations. This enables yeast cells to strike a fine balance between H2 O2 removal and limitation of matrix glutathione oxidation.

Artemisinin Attenuated Hydrogen Peroxide (H2O2)-Induced Oxidative Injury in SH-SY5Y and Hippocampal Neurons via the Activation of AMPK Pathway

Oxidative stress is believed to be one of the main causes of neurodegenerative diseases such as Alzheimer’s disease (AD). The pathogenesis of AD is still not elucidated clearly but oxidative stress is one of the key hypotheses. Here, we found that artemisinin, an anti-malarial Chinese medicine, possesses neuroprotective effects. However, the antioxidative effects of artemisinin remain to be explored. In this study, we found that artemisinin rescued SH-SY5Y and hippocampal neuronal cells from hydrogen peroxide (H₂O₂)-induced cell death at clinically relevant doses in a concentration-dependent manner. Further studies showed that artemisinin significantly restored the nuclear morphology, improved the abnormal changes in intracellular reactive oxygen species (ROS), reduced the mitochondrial membrane potential, and caspase-3 activation, thereby attenuating apoptosis. Artemisinin also stimulated the phosphorylation of the adenosine monophosphate -activated protein kinase (AMPK) pathway in SH-SY5Y cells in a time- and concentration-dependent manner. Inhibition of the AMPK pathway attenuated the protective effect of artemisinin. These data put together suggested that artemisinin has the potential to protect neuronal cells. Similar results were obtained in primary cultured hippocampal neurons. Cumulatively, these results indicated that artemisinin protected neuronal cells from oxidative damage, at least in part through the activation of AMPK. Our findings support the role of artemisinin as a potential therapeutic agent for neurodegenerative diseases.

FMRpolyG alters mitochondrial transcripts level and respiratory chain complex assembly in Fragile X associated tremor/ataxia syndrome [FXTAS]

Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disorder caused by an expansion of 55 to 200 CGG repeats (premutation) in FMR1. These CGG repeats are Repeat Associated non-ATG (RAN) translated into a small and pathogenic protein, FMRpolyG. The cellular and molecular mechanisms of FMRpolyG toxicity are unclear. Various mitochondrial dysfunctions have been observed in FXTAS patients and animal models. However, the causes of these mitochondrial alterations are not well understood. In the current study, we investigated interaction of FMRpolyG with mitochondria and its role in modulating mitochondrial functions. Beside nuclear inclusions, FMRpolyG also formed small cytosolic aggregates that interact with mitochondria both in cell and mouse model of FXTAS. Importantly, expression of FMRpolyG reduces ATP levels, mitochondrial transmembrane potential, mitochondrial supercomplexes assemblies and activities and expression of mitochondrial DNA encoded transcripts in cell and animal model of FXTAS, as well as in FXTAS patient brain tissues. Overall, these results suggest that FMRpolyG alters mitochondrial functions, bioenergetics and initiates cell death. The further study in this direction will help to establish the role of mitochondria in FXTAS conditions.

Characteristics and in vitro anti-skin aging activity of gallic acid loaded in cationic CTAB niosome

Physicochemical characteristics and in vitro anti-skin aging activity of gallic acid loaded in niosomes were investigated. Gallic acid was loaded in neutral (Brij 52/cholesterol at 7:3) and cationic CTAB niosomes (Brij 52/cholesterol/cetyltrimethylammonium bromide at 7:3:0.65). The maximum loading capacity and entrapment efficiency of gallic acid were 3.5, 4.48 ± 2.10 in neutral and 50%, w/w, 10.94 ± 0.78% in cationic CTAB niosomes, respectively. All gallic acid loaded in niosomes showed the unilamellar structure under transmission electron microscope with size range of 131.23-508.03 nm at initial and after storage for 3 months. The highest remaining percentage of gallic acid at all storage temperatures after 3 months was about 77% when loaded in the cationic CTAB niosome, whereas gallic acid in solution was about 64%. The release profiles of gallic acid loaded in neutral and cationic CTAB niosomes revealed the gradual release in 24 h. The cytotoxicity of gallic acid loaded in neutral and cationic CTAB niosomes appeared the non-cytotoxic effect in B16F10 melanoma cells and human skin fibroblasts. The cationic CTAB niosome loaded with gallic acid demonstrated the highest anti-skin aging activity, including melanin suppression effect (55.92 ± 4.92% of control) by inhibition of tyrosinase (53.18 ± 3.67% of control) and tyrosinase-related protein-2 (24.61 ± 7.92% of control), antioxidant (87.03 ± 0.99% cell viability) and inhibition of matrix metalloproteinase-2 (38.46 ± 1.53% of control). This study has demonstrated the superior stability and anti-skin aging activity of gallic acid loaded in cationic CTAB niosome for potential utilization in pharmaceutical and cosmetic products.

Comparative evaluation of four triterpenoid glycoside saponins of bacoside A in alleviating sub-cellular oxidative stress of N2a neuroblastoma cells

OBJECTIVES

To examine the neuroprotective property of triterpenoid glycoside saponins of Bacopa monnieri (L.) Wettst. bacoside A and its components against H₂ O₂ -induced oxidative stress on neuronal (N2a) cells.

METHODS

The cytoprotective effects of individual bacoside A components were evaluated towards oxidative stressed neuronal cells. Bacoside A was screened for neuronal cell viability (MTT assay) and change in intracellular reactive oxygen species (ROS), anti-apoptotic properties and mitochondrial membrane potential (MMP) using fluorescence microscopy.

KEY FINDINGS

Different bacoside A components showed decrease in N2a cell viability below 100 (%) after bacoside A concentration of 0.4 mg/ml. Further, cytoprotective effect of optimized dose of bacoside A was analysed for alleviating oxidative stressed, apoptosis and MMP in H₂ O₂ stressed neuronal cells. Results showed increase in MMP, and decrease in apoptotic induction, without much change in nuclear integrity in stressed neuronal cells. Results showed bacoside A3 and bacopaside II have comparatively higher cytoprotective ability whilst isomer of bacopasponin C, bacopasaponin C and mixture showed comparatively less response.

CONCLUSIONS

Amongst four different bacoside A components, bacoside A3 and bacopaside II showed comparatively higher neuroprotective response analysed as higher cell viability and decreased intracellular ROS, suggesting better regulation of cyto-(neuronal) protection of N2a cells.

Epigallocatechin Gallate Protects against TNFα- or H2O2- Induced Apoptosis by Modulating Iron Related Proteins in a Cell Culture Model

Abstract. Oxidative stress, iron dysregulation, and inflammation have been implicated in the pathogenesis of Parkinson’s disease (PD). Considering the entwined relationship among these factors, epigallocatechin gallate (EGCG) may be a good candidate for PD treatment due to its protective effects against those factors. The objective of this study is to determine whether EGCG protects N27 dopaminergic neuronal cells from H2O2 - and TNFα- induced neurotoxicity. Seven treatments were included: control, H2O2, TNFα, FeSO4, H2O2 + EGCG, TNFα + EGCG, FeSO4 + EGCG. Cells were pretreated with 10 μM EGCG, followed by 50 μM H2O2, 30 ng/ml TNFα or 50 μM FeSO4. Neuroprotective effects of EGCG were assessed by cell viability assay, caspase-3 activity, intracellular reactive oxygen species (ROS) generation, and iron related protein expressions. Caspase-3 activity was increased to 2.8 fold (P < 0.001) and 1.5 fold (P < 0.01) with H2O2 and TNFα treatment; However, EGCG pretreatment significantly decreased the caspase activity by 50.2% (P < 0.001) and 30.1% (P < 0.05). Similarly, cell viability was reduced to 69.2% (P < 0.01) and 89% (P < 0.01) by H2O2 and TNFα, which was partially blocked by EGCG pretreatment. Also, EGCG significantly (P < 0.001) protected against H2O2- induced ROS in a time dependent manner. In addition, both H2O2 and TNFα significantly (P < 0.05) upregulated hepcidin expression and marginally reduced ferroportin (Fpn) expression unlike iron treatment alone. Collectively, our results show that EGCG protects against both TNFα- and H2O2- induced neuronal apoptosis. The observed neuroprotection may be through the inhibition of oxidative stress and inflammation which is possibly mediated mainly by hepcidin and partially by Fpn.

Antioxidative properties and structural features of atypical 2-Cys peroxiredoxin from Sebastes schlegelii

Atypical 2-Cys peroxiredoxin (Prx5) is an antioxidant protein that exerts its antioxidant function by detoxifying different reactive oxygen species (ROS). Here, we identified mitochondrial Prx5 from rockfish (SsPrx5) and described its specific structural and functional characteristics. The open reading frame (ORF) of SsPrx5 (570 bp) was translated into a 190-amino acid polypeptide that contained a mitochondrial targeting sequence (MTS), thioredoxin 2 domain, two Prx-specific signature motifs, and three conserved cysteine residues. Sequence comparison indicated that the SsPrx5 protein sequence shared greatest identity with teleost orthologs, where the phylogenetic results showed an evolutionary position within the fish Prx5. The coding sequence of SsPrx5 was scattered in six exons as found in other vertebrates. Additionally, the potent antioxidant functions of recombinantly expressed SsPrx5 protein was demonstrated by insulin reduction and extracellular H₂O₂ scavenging both in vitro and in vivo. Quantitative real time PCR (qPCR) detected ubiquitous mRNA expression of SsPrx5 in healthy rockfish tissues, with remarkable expression observed in gill, liver, and reproductive tissues. Prompt transcription of SsPrx5 was shown in the immune-stimulated gill and liver tissues against Streptococcus iniae and lipopolysaccharide injection. Taken together, present results suggest the indispensable role of SsPrx5 in the rockfish antioxidant defense system against oxidative stresses and its role in maintaining redox balance upon pathogen invasion.

Synthesis and Evaluation of Two Novel All -trans-Retinoic Acid Conjugates: Biocompatible and Functional Tools for Retina Research

The vitamin A derivative all- trans-retinoic acid (ATRA) is an important biologically active metabolite that regulates a variety of essential biological processes in particular via gene-regulatory mechanisms. In the retina, ATRA is a light-dependent byproduct of the phototransduction cascade. Here, ATRA is not only needed for proper retinal development, but it also acts as a neuromodulator on horizontal cells, second-order inhibitory neurons in the outer retina, which reveal morphological and physiological changes when the retina is treated with ATRA. There is evidence that gene-regulatory mechanisms may only be partially involved in these neuromodulatory processes and the underlying nontranscriptional mechanisms are still elusive. This is, among other things, due to the lack of appropriately labeled ATRA, which would allow the tracking of ATRA in cells or a given tissue. To overcome this obstacle, we designed, synthesized, and evaluated two conjugates of ATRA, one conjugated with biotin (biotin-ATRA) and one conjugated with diaminoterephthalate fluorophore (DAT-ATRA), as molecular tools for different fields of application. The biocompatibility of both compounds was demonstrated via cell viability assays in cultured N2a-cells. N2a-cells exposed to the compounds showed no significant changes in the viability rate. The functionality of synthesized ATRA-conjugates was verified using retinal tissue derived from adult carp. The binding of ATRA-conjugates to distinct retinal cells was assessed in primary cultures of carp retina. Hereby, horizontal and Müller cells have been identified as specific target cells of the new ATRA compounds. Electron microscopy further confirmed that the new substances are still able to induce synaptic plasticity at horizontal cell dendrites resulting in formation of spine synapses, as it is shown for native ATRA. Taken together, the novel ATRA-conjugates represent biocompatible and functional molecular tools, which may further provide the possibility to track ATRA in neuronal cells and study its modulatory effects in different cell systems.

Investigation into the intracellular fates, speciation and mode of action of selenium-containing neuroprotective agents using XAS and XFM

BACKGROUND

A variety of selenium compounds have been observed to provide protection against oxidative stress, presumably by mimicking the mechanism of action of the glutathione peroxidases. However, the selenium chemistry that underpins the action of these compounds has not been unequivocally established.

METHODS

The synchrotron based techniques, X-ray absorption spectroscopy and X-ray fluorescence microscopy were used to examine the cellular speciation and distribution of selenium in SH-SY5Y cells pretreated with one of two diphenyl diselenides, or ebselen, followed by peroxide insult.

RESULTS

Bis(2-aminophenyl)diselenide was shown to protect against oxidative stress conditions which mimic ischemic strokes, while its nitro analogue, bis(2-nitrophenyl)diselenide did not. This protective activity was tentatively assigned to the reductive cleavage of bis(2-aminophenyl)diselenide inside human neurocarcinoma cells, SH-SY5Y, while bis(2-nitrophenyl)diselenide remained largely unchanged. The distinct chemistries of the related compounds were traced by the changes in selenium speciation in bulk pellets of treated SH-SY5Y cells detected by X-ray absorption spectroscopy. Further, bis(2-aminophenyl)diselenide, like the known stroke mitigation agent ebselen, was observed by X-ray fluorescence imaging to penetrate into the nucleus of SH-SY5Y cells while bis(2-nitrophenyl)diselenide was observed to be excluded from the nuclear region.

CONCLUSIONS

The differences in activity were thus attributed to the varied speciation and cellular localisation of the compounds, or their metabolites, as detected by X-ray absorption spectroscopy and X-ray fluorescence microscopy.

SIGNIFICANCE

The work is significant as it links, for the first time, the protective action of selenium compounds against redox stress with particular chemical speciation using a direct measurement approach.

Structural Basis for Inhibitor-Induced Hydrogen Peroxide Production by Kynurenine 3-Monooxygenase

Kynurenine 3-monooxygenase (KMO) inhibitors have been developed for the treatment of neurodegenerative disorders. The mechanisms of flavin reduction and hydrogen peroxide production by KMO inhibitors are unknown. Herein, we report the structure of human KMO and crystal structures of Saccharomyces cerevisiae (sc) and Pseudomonas fluorescens (pf) KMO with Ro 61-8048. Proton transfer in the hydrogen bond network triggers flavin reduction in p-hydroxybenzoate hydroxylase, but the mechanism triggering flavin reduction in KMO is different. Conformational changes via π-π interactions between the loop above the flavin and substrate or non-substrate effectors lead to disorder of the C-terminal α helix in scKMO and shifts of domain III in pfKMO, stimulating flavin reduction. Interestingly, Ro 61-8048 has two different binding modes. It acts as a competitive inhibitor in scKMO and as a non-substrate effector in pfKMO. These findings provide understanding of the catalytic cycle of KMO and insight for structure-based drug design of KMO inhibitors.

Alkylated resveratrol prodrugs and metabolites as potential therapeutics for neurodegenerative diseases

Resveratrol is a naturally occurring stilbene which has shown promising results as treatment for several neurodegenerative diseases. However, its application is limited due to its low efficacy and bioavailability. Here, we have designed and synthesized alkylated resveratrol prodrugs combining structural modification to improve antioxidant and anti-inflammatory properties and the preparation of prodrugs to extend drug bioavailability. For comparison we also studied resveratrol prodrugs and alkylated resveratrol derivatives. Methylated and butylated resveratrol derivatives showed the best in vitro neuroprotective and anti-inflammatory activity. The glucosyl- and glucosyl-acyl- prodrugs of these derivatives showed lower toxicity on zebra fish embryo. When neuroprotection was examined on pentylenetetrazole challenged zebra fish, they were capable of reverting neuronal damage but to a lower extent than resveratrol. Nevertheless, 3-O-(6'-O-octanoyl)-β-d-glucopyranoside resveratrol (compound 8) recovered AChE activity over 100% whereas resveratrol only up to 92%. In a 3-nitropropionic acid mice model of Huntington's disease, resveratrol derivative 8 delayed the onset and reduced the severity of HD-like symptoms, by improving locomotor activity and protecting against weight loss. Its effects involved an equal antioxidant but better anti-inflammatory profile than resveratrol as shown by SOD2 expression in brain tissue and circulating levels of IL-6 (11 vs 18 pg/mL), respectively. Finally, the octanoyl chain in compound 8 could be playing a role in inflammation and neuronal development indicating it could be acting as a double-drug, instead of as a prodrug.

Polyethylene glycol–gelatin hydrogels with tuneable stiffness prepared by horseradish peroxidase-activated tetrazine–norbornene ligation

Mild oxidation of dihydrogen tetrazine by horseradish peroxidase was utilised in bioorthogonal crosslinking, via tetrazine–norbornene ligation, of polyethylene glycol–gelatin hydrogels.