d-β-Hydroxybutyrate inhibited the apoptosis of PC12 cells induced by H2O2 via inhibiting oxidative stress

β-Hydroxybutyrate Protects Against Cisplatin-Induced Renal Damage via Regulating Ferroptosis

Cisplatin is a particularly potent antineoplastic drug. However, its usefulness is restricted due to the induction of nephrotoxicity. More recent research has indicated that β-hydroxybutyrate (β-HB) protects against acute or chronic organ damage as an efficient healing agent. Nonetheless, the therapeutic mechanisms of β-HB in acute kidney damage caused by chemotherapeutic drugs remain unclear. Our study developed a model of cisplatin-induced acute kidney injury (AKI), which involved the administration of a ketogenic diet or β-HB. We analyzed blood urea nitrogen (BUN) and creatinine (Cr) levels in serum, and used western blotting and immunohistochemical staining to assess ferroptosis and the calcium/calmodulin-dependent kinase kinase 2 (Camkk2)/AMPK pathway. The mitochondrial morphology and function were examined. Additionally, we conducted in vivo and in vitro experiments using selective Camkk2 inhibitor or activator to investigate the protective mechanism of β-HB on cisplatin-induced AKI. Exogenous or endogenous β-HB effectively alleviated cisplatin-induced abnormally elevated levels of BUN and Cr and renal tubular necrosis in vivo. Additionally, β-HB reduced ferroptosis biomarkers and increased the levels of anti-ferroptosis biomarkers in the kidney. β-HB also improved mitochondrial morphology and function. Moreover, β-HB significantly attenuated cisplatin-induced cell ferroptosis and damage in vitro. Furthermore, western blotting and immunohistochemical staining indicated that β-HB may prevent kidney injury by regulating the Camkk2-AMPK pathway. The use of the Camkk2 inhibitor or activator verified the involvement of Camkk2 in the renal protection by β-HB. This study provided evidence of the protective effects of β-HB against cisplatin-induced nephrotoxicity and identified inhibited ferroptosis and Camkk2 as potential molecular mechanisms.

Construction of Phlorotannin-Based Nanoparticles for Alleviating Acute Liver Injury

Acute liver injury (ALI) is a severe health condition with limited treatment options. Phlorotannin (PT), a natural compound extracted from seaweeds, has shown potential in improving liver function. However, its poor stability and bioavailability have limited its applications in vivo. In this study, we developed PT-based nanoparticles (NPs) through a Mannich reaction with glycine, which exhibited good biocompatibility and prolonged circulation time in vivo. Our results revealed that the PT NPs possess strong free radical scavenging ability, effectively reducing reactive oxygen species (ROS) and alleviating oxidative stress and proinflammatory responses in the H2O2-induced oxidative damage model of HepG2 cells. Furthermore, the PT NPs effectively attenuated oxidative stress and inflammation in the liver tissue of carbon tetrachloride (CCl4)-induced liver injury mice by regulating the Nrf2/HO-1 signaling pathway. In summary, our results suggested that the PT NPs could serve as a promising nano-therapeutic strategy for alleviating ALI.

β-hydroxybutyrate impairs bovine oocyte maturation via pyruvate dehydrogenase (PDH) associated energy metabolism abnormality

Background: Ketosis is one of the most frequent and costly metabolic disorders in high-producing dairy cows, and negatively associated with the health and reproductive performance of bovine. Ketosis is mainly caused by the accumulation of ketone body β-hydroxybutyric acid and its diagnosis is based on β-hydroxybutyrate (βHB) concentration in blood. Methods: In this study, we investigated the effects of βHB on bovine oocyte maturation in the concentration of subclinical (1.2 mM) βHB and clinical (3.6 mM). Results: The results showed βHB disrupted bovine oocyte maturation and development capacity. Further analysis showed that βHB induced oxidative stress and mitochondrial dysfunction, as indicated by the increased level of reactive oxygen species (ROS), disrupted mitochondrial structure and distribution, and depolarized membrane potential. Furthermore, oxidative stress triggered early apoptosis, as shown by the enhanced levels of Caspase-3 and Annexin-V. Moreover, 3.6 mM βHB induced the disruption of the pyruvate dehydrogenase (PDH) activity, showing with the decrease of the global acetylation modification and the increase of the abnormal spindle rate. Conclusion: Our study showed that βHB in subclinical/clinical concentration had toxic effects on mitochondrial function and PDH activity, which might affect energy metabolism and epigenetic modification of bovine oocytes and embryos.

Decreased β-hydroxybutyrate and ketogenic amino acid levels in depressed human adults

β-hydroxybutyrate (BHB) is a major ketone body synthesized mainly in the liver mitochondria and is associated with stress and severity of depression in humans. It is known to alleviate depressive-like behaviors in mouse models of depression. In this study, plasma BHB, ketogenic and glucogenic amino acids selected from the Tohoku Medical Megabank Project Community-Based Cohort Study were analysed and measured using nuclear magnetic resonance spectroscopy. The Center for Epidemiologic Studies Depression Scale (CES-D) was utilized to select adult participants with depressive symptoms (CES-D ≥ 16; n = 5722) and control participants (CES-D < 16; n = 18,150). We observed significantly reduced plasma BHB, leucine, and tryptophan levels in participants with depressive symptoms. Using social defeat stress (SDS) mice models, we found that BHB levels in mice sera increased after acute SDS, but showed no change after chronic SDS, which differed from human plasma results. Furthermore, acute SDS increased mitochondrial BHB levels in the prefrontal cortex at 6 h. In contrast, chronic SDS significantly increased the amount of food intake but reduced hepatic mitochondrial BHB levels in mice. Moreover, gene transcriptions of voltage-dependent anion-selective channel 1 (Vdac1) and monocarboxylic acid transporter 1 (Mct1), major molecules relevant to mitochondrial biogenesis and BHB transporter, significantly decreased in the liver and PFC after chronic SDS exposure. These results provide evidence that hepatic and prefrontal mitochondrial biogenesis plays an important role in BHB synthesis under chronic stress and in humans with depressive symptoms.

Oxidative Stress and Aging as Risk Factors for Alzheimer's Disease and Parkinson's Disease: The Role of the Antioxidant Melatonin

Aging and neurodegenerative diseases share common hallmarks, including mitochondrial dysfunction and protein aggregation. Moreover, one of the major issues of the demographic crisis today is related to the progressive rise in costs for care and maintenance of the standard living condition of aged patients with neurodegenerative diseases. There is a divergence in the etiology of neurodegenerative diseases. Still, a disturbed endogenous pro-oxidants/antioxidants balance is considered the crucial detrimental factor that makes the brain vulnerable to aging and progressive neurodegeneration. The present review focuses on the complex relationships between oxidative stress, autophagy, and the two of the most frequent neurodegenerative diseases associated with aging, Alzheimer's disease (AD) and Parkinson's disease (PD). Most of the available data support the hypothesis that a disturbed antioxidant defense system is a prerequisite for developing pathogenesis and clinical symptoms of ADs and PD. Furthermore, the release of the endogenous hormone melatonin from the pineal gland progressively diminishes with aging, and people's susceptibility to these diseases increases with age. Elucidation of the underlying mechanisms involved in deleterious conditions predisposing to neurodegeneration in aging, including the diminished role of melatonin, is important for elaborating precise treatment strategies for the pathogenesis of AD and PD.

β-Hydroxybutyric acid improves cognitive function in a model of heat stress by promoting adult hippocampal neurogenesis

Heat stress has multiple potential effects on the brain, such as neuroinflammation, neurogenesis defects, and cognitive impairment. β-hydroxybutyric acid (BHBA) has been demonstrated to play neuroprotective roles in various models of neurological diseases. In the present study, we investigated the efficacy of BHBA in alleviating heat stress-induced impairments of adult hippocampal neurogenesis and cognitive function, as well as the underlying mechanisms. Mice were exposed to 43 ℃ for 15 min for 14 days after administration with saline, BHBA, or minocycline. Here, we showed for the first time that BHBA normalized memory ability in the heat stress-treated mice and attenuated heat stress-impaired hippocampal neurogenesis. Consistently, BHBA noticeably improved the synaptic plasticity in the heat stress-treated hippocampal neurons by inhibiting the decrease of synapse-associated proteins and the density of dendritic spines. Moreover, BHBA inhibited the expression of cleaved caspase-3 by suppressing endoplasmic reticulum (ER) stress, and increased the expression of brain-derived neurotrophic factor (BDNF) in the heat stress-treated hippocampus by activating the protein kinase B (Akt)/cAMP response element binding protein (CREB) and methyl-CpG binding protein 2 (MeCP2) pathways. These findings indicate that BHBA is a potential agent for improving cognitive functions in heat stress-treated mice. The action may be mediated by ER stress, and Akt-CREB-BDNF and MeCP2 pathways to improve adult hippocampal neurogenesis and synaptic plasticity.

Ketone body augmentation decreases methacholine hyperresponsiveness in mouse models of allergic asthma

Background

Individuals with allergic asthma exhibit lung inflammation and remodeling accompanied by methacholine hyperresponsiveness manifesting in proximal airway narrowing and distal lung tissue collapsibility, and they can present with a range of mild-to-severe disease amenable or resistant to therapeutic intervention, respectively. There remains a need for alternatives or complements to existing treatments that could control the physiologic manifestations of allergic asthma.

Objectives

Our aim was to examine the hypothesis that because ketone bodies elicit anti-inflammatory activity and are effective in mitigating the methacholine hyperresponsiveness associated with obese asthma, increasing systemic concentrations of ketone bodies would diminish pathologic outcomes in asthma-relevant cell types and in mouse models of allergic asthma.

Methods

We explored the effects of ketone bodies on allergic asthma-relevant cell types (macrophages, airway epithelial cells, CD4 T cells, and bronchial smooth muscle cells) in vitro as well as in vivo by using preclinical models representative of several endotypes of allergic asthma to determine whether promotion of ketosis through feeding a ketogenic diet or providing a ketone precursor or a ketone ester dietary supplement could affect immune and inflammatory parameters as well as methacholine hyperresponsiveness.

Results

In a dose-dependent manner, the ketone bodies acetoacetate and β-hydroxybutyrate (BHB) decreased proinflammatory cytokine secretion from mouse macrophages and airway epithelial cells, decreased house dust mite (HDM) extract-induced IL-8 secretion from human airway epithelial cells, and decreased cytokine production from polyclonally and HDM-activated T cells. Feeding a ketogenic diet, providing a ketone body precursor, or supplementing the diet with a ketone ester increased serum BHB concentrations and decreased methacholine hyperresponsiveness in several acute HDM sensitization and challenge models of allergic asthma. A ketogenic diet or ketone ester supplementation decreased methacholine hyperresponsiveness in an HDM rechallenge model of chronic allergic asthma. Ketone ester supplementation synergized with corticosteroid treatment to decrease methacholine hyperresponsiveness in an HDM-driven model of mixed-granulocytic severe asthma. HDM-induced morphologic changes in bronchial smooth muscle cells were inhibited in a dose-dependent manner by BHB, as was HDM protease activity.

Conclusions

Increasing systemic BHB concentrations through dietary interventions could provide symptom relief for several endotypes of allergic asthmatic individuals through effects on multiple asthma-relevant cells.

Facile synthesis of food-grade and size-controlled nanocarriers based on self-assembly of procyanidins and phycocyanin

Nanocarriers provide the possibility to overcome the low solubility, poor stability, and low bioavailability of functional factors. However, most nanocarriers do not directly participate in the corresponding effects of functional factors, such as treating inflammatory bowel disease but lack the means to control their size accurately. Herein, nanocarriers were prepared by a one-pot method, using food-grade antioxidant procyanidins, vanillin, and phycocyanin as raw materials. The strategy involved the Mannich reaction among the phenolic hydroxyl groups of procyanidins, the aldehyde groups of vanillin, and the amino groups of phycocyanin. The obtained nanocarriers displayed controllable sizes ranging from 130 to 750 nm, showing good antioxidant capacity in scavenging free radicals and were biocompatible to Caco-2 cells and RAW 264.7 macrophages. Nanocarriers also exhibited an inhibitory effect on cell damage induced by acrylamide and H₂O₂. Moreover, the designed nanocarriers could be used for delivering active ingredients such as lutein, which showed a uniform spherical distribution, high encapsulation efficiency, and good biocompatibility. This work provides a facile synthesis method to prepare food-grade nanocarriers with functional properties, which can be potentially used in the delivery of functional factors.

β-Hydroxybutyric acid attenuates heat stress-induced neuroinflammation via inhibiting TLR4/p38 MAPK and NF-κB pathways in the hippocampus

Heat stress causes many pathophysiological responses in the brain, including neuroinflammation and cognitive deficits. β-Hydroxybutyric acid (BHBA) has been shown to have neuroprotective effects against inflammation induced by lipopolysaccharide. The aim of the present study was to evaluate the effects of BHBA on neuroinflammation induced by heat stress, as well as the underlying mechanisms. Mice were pretreated with vehicle, BHBA or minocycline (positive control group) and followed by heat exposure (43°C) for 15 min for 14 days. In mice subjected to heat stress, we found that treatment with BHBA or minocycline significantly decreased the level of serum cortisol, the expressions of heat shock protein 70 (HSP70), and the density of c-Fos⁺ cells in the hippocampus. Surprisingly, the ethological tests revealed that heat stress led to cognitive dysfunctions and could be alleviated by BHBA and minocycline administration. Further investigation showed that BHBA and minocycline significantly attenuated the activation of microglia and astrocyte induced by heat stress. Pro-inflammatory cytokines were attenuated in the hippocampus by BHBA and minocycline treatment. Importantly, compared with the heat stress group, mice in the BHBA treatment group and positive control group experienced a decrease in the expressions of toll-like receptor 4 (TLR4), phospho-p38 (p-p38), and nuclear factor kappa B (NF-κB). Our results elucidated that BHBA inhibits neuroinflammation induced by heat stress by suppressing the activation of microglia and astrocyte, and modulating TLR4/p38 MAPK and NF-κB pathways. This study provides new evidence that BHBA is a potential strategy for protecting animals from heat stress.

β-Hydroxybutyrate Alleviates Low Glucose-Induced Apoptosis via Modulation of ROS-Mediated p38 MAPK Signaling

Hypoglycemia has emerged as a prominent complication in anti-diabetic drug therapy or negative energy balance of animals, which causes brain damage, cognitive impairment, and even death. Brain injury induced by hypoglycemia is closely related to oxidative stress and the production of reactive oxygen species (ROS). The intracellular accumulation of ROS leads to neuronal damage, even death. Ketone body β-hydroxybutyrate (BHBA) not only serves as alternative energy source for glucose in extrahepatic tissues, but is also involved in cellular signaling transduction. Previous studies showed that BHBA reduces apoptosis by inhibiting the excessive production of ROS and activation of caspase-3. However, the effects of BHBA on apoptosis induced by glucose deprivation and its related molecular mechanisms have been seldom reported. In the present study, PC12 cells and primary cortical neurons were used to establish a low glucose injury model. The effects of BHBA on the survival and apoptosis in a glucose deficient condition and related molecular mechanisms were investigated by using flow cytometry, immunofluorescence, and western blotting. PC12 cells were incubated with 1 mM glucose for 24 h as a low glucose cell model, in which ROS accumulation and cell mortality were significantly increased. After 24 h and 48 h treatment with different concentrations of BHBA (0 mM, 0.05 mM, 0.5 mM, 1 mM, 2 mM), ROS production was significantly inhibited. Moreover, cell apoptosis rate was decreased and survival rate was significantly increased in 1 mM and 2 mM BHBA groups. In primary cortical neurons, at 24 h after treatment with 2 mM BHBA, the injured length and branch of neurites were significantly improved. Meanwhile, the intracellular ROS level, the proportion of c-Fos⁺ cells, apoptosis rate, and nuclear translocation of NF-κB protein after treatment with BHBA were significantly decreased when compared with that in low glucose cells. Importantly, the expression of p38, p-p38, NF-κB, and caspase-3 were significantly decreased, while the expression of p-ERK was significantly increased in both PC12 cells and primary cortical neurons. Our results demonstrate that BHBA decreased the accumulation of intracellular ROS, and further inhibited cell apoptosis by mediating the p38 MAPK signaling pathway and caspase-3 apoptosis cascade during glucose deprivation. In addition, BHBA inhibited apoptosis by activating ERK phosphorylation and alleviated the damage of low glucose to PC12 cells and primary cortical neurons. These results provide new insight into the anti-apoptotic effect of BHBA in a glucose deficient condition and the related signaling cascade.

Therapeutic ketosis decreases methacholine hyperresponsiveness in mouse models of inherent obese asthma

Obese asthmatics tend to have severe, poorly controlled disease and exhibit methacholine hyperresponsiveness manifesting in proximal airway narrowing and distal lung tissue collapsibility. Substantial weight loss in obese asthmatics or in mouse models of the condition decreases methacholine hyperresponsiveness. Ketone bodies are rapidly elevated during weight loss, coinciding with or preceding relief from asthma-related comorbidities. As ketone bodies may exert numerous potentially therapeutic effects, augmenting their systemic concentrations is being targeted for the treatment of several conditions. Circulating ketone body levels can be increased by feeding a ketogenic diet or by providing a ketone ester dietary supplement, which we hypothesized would exert protective effects in mouse models of inherent obese asthma. Weight loss induced by feeding a low-fat diet to mice previously fed a high-fat diet was preceded by increased urine and blood levels of the ketone body β-hydroxybutyrate (BHB). Feeding a ketogenic diet for 3 wk to high-fat diet-fed obese mice or genetically obese db/db mice increased BHB concentrations and decreased methacholine hyperresponsiveness without substantially decreasing body weight. Acute ketone ester administration decreased methacholine responsiveness of normal mice, and dietary ketone ester supplementation of high-fat diet-fed mice decreased methacholine hyperresponsiveness. Ketone ester supplementation also transiently induced an "antiobesogenic" gut microbiome with a decreased Fermicutes/Bacteroidetes ratio. Dietary interventions to increase systemic BHB concentrations could provide symptom relief for obese asthmatics without the need for the substantial weight loss required of patients to elicit benefits to their asthma through bariatric surgery or other diet or lifestyle alterations.

The protective role of PHB and its degradation products against stress situations in bacteria

Many bacteria produce storage biopolymers that are mobilized under conditions of metabolic adaptation, for example, low nutrient availability and cellular stress. Polyhydroxyalkanoates are often found as carbon storage in Bacteria or Archaea, and of these polyhydroxybutyrate (PHB) is the most frequently occurring PHA type. Bacteria usually produce PHB upon availability of a carbon source and limitation of another essential nutrient. Therefore, it is widely believed that the function of PHB is to serve as a mobilizable carbon repository when bacteria face carbon limitation, supporting their survival. However, recent findings indicate that bacteria switch from PHB synthesis to mobilization under stress conditions such as thermal and oxidative shock. The mobilization products, 3-hydroxybutyrate and its oligomers, show a protective effect against protein aggregation and cellular damage caused by reactive oxygen species and heat shock. Thus, bacteria should have an environmental monitoring mechanism directly connected to the regulation of the PHB metabolism. Here, we review the current knowledge on PHB physiology together with a summary of recent findings on novel functions of PHB in stress resistance. Potential applications of these new functions are also presented.

Effect of Anoectochilus roxburghii flavonoids extract on H2O2 - Induced oxidative stress in LO2 cells and D-gal induced aging mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii (A. roxburghii) is a popular folk medicine in many Asian countries, which has been used traditionally for treatment of some diseases such as diabetes, tumors, hyperlipemia, and hepatitis. The ethanol extract from A. roxburghii was recently shown to exert better ability to scavenge free radicals in vitro and possess antioxidant on natural aging mice in vivo.

AIM OF THE STUDY

This study is to characterize the chemical composition, and investigate the protective effect of the A. roxburghii flavonoids extract (ARF) against hydrogen peroxide (H₂O₂)-induced oxidative stress in LO2 cells in vitro and D-galactose (D-gal)-induced aging mice model in vivo, and explore the underlying mechanisms.

MATERIALS AND METHODS

The chemical components of the flavonoids extract fromA. roxburghii were detected by ultraperformance lipid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). H₂O₂ was used to establish an oxidative stress model in LO2 cells. Cytotoxic and protective effects of ARF on the LO2 cells were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Moreover, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in cell supernatants were measured by commercial reagent kits. Kun-Ming mice were induced to aging with D-gal (400 mg/kg, BW) by subcutaneous injection for 58 days. From the 28th day to the 58th day of D-gal treatment, ARF (122.5, 245 and 490 mg/kg, BW) and vitamin E (100 mg/kg, BW) were orally administrated to aging mice once a day for consecutive 30 days. After 25 days of the treatment with ARF, learning and memory were assessed using Morris Water Maze (MWM). At the end of the test period, the animals were euthanized by cervical dislocation, and the levels of SOD, GSH-PX, and MDA in serum, liver homogenates and brain homogenates were measured. The levels of monoamine oxidase (MAO) and acetylcholinesterase (AchE) were determined in brain homogenates. Skin and liver histopathological morphology were observed by H&E staining. Furthermore, antioxidant-related gene expression levels in the liver were carried out by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Nine flavonoids were identified in the extracts of A. roxburghii. In vitro assay, a high concentration of ARF (>612.5 μg/ml) reduced the survival rate and had toxic effects on LO2 cells. In addition, ARF (245 μg/ml, 490 μg/ml) and Vitamin C (200 μg/ml) markedly inhibited generations of MDA and increased activities of SOD, GSH-PX in H₂O₂-induced LO2 cells supernatants. In vivo assay, ARF (122.5 mg/kg, 245 mg/kg and 490 mg/kg) and Vitamin E (100 mg/kg) not only ameliorated learning and memory ability but also improved skin and liver pathological alterations. Strikingly, ARF significantly decreased MDA and MAO levels, markedly enhanced antioxidant enzyme (SOD and GSH-PX) activities. Further, compared to the D-gal group, ARF could obviously up-regulate glutathione peroxidase-1 (GPx-1) and glutathione peroxidase-4 (GPx-4) mRNA levels.

CONCLUSIONS

These findings suggested that ARF protects LO2 cells against H₂O₂-induced oxidative stress and exerts the potent anti-aging effects in D-gal aging mice model, which may be related to the inhibition of oxidative stress. Flavonoid compounds may contribute to the anti-oxidative capability and modulating aging.

Brazilin Treatment Produces Antidepressant- and Anxiolytic-Like Effects in Mice

Increasing evidence shows depression relevant to oxidative stress and inflammation. Anti-inflammatory strategies or antioxidants have led to the development of new antidepressants. Brazilin is a natural product from the Chinese traditional medicine Caesalpinia sappan L., exerting anti-inflammatory, antioxidant, anti-platelet concentration, and anti-cancer effects. While the antidepressant effect of brazilin is largely unknown. In present study, we investigated the effects of brazilin on H₂O₂-induced oxidative injury in PC12 cells and on depression- and anxiety-like behaviors of chronically mild stressed (CMS)-induced depression mice. It was found that brazilin pre-treatment (both 10 and 20 µM) significantly increased cell viability and decreased cell apoptosis in H₂O₂-treated PC12 cells. Furthermore, repetitive administration of brazilin to CMS-induced depression mice by intraperitoneal injection (10 mg/kg) made the mice significantly lose their latency of feeding in novelty-suppressed feeding test (NSF), have more the sucrose preference in sucrose preference test (SPT), and more time spent in the central zone without affecting their crossing activity in open field test (OFT). These results suggested that brazilin can play a role in antidepressant and anxiolytic-like behaviors for CMS-induced depression mice probably through inhibiting the oxidative stress. Therefore, brazilin is worth to be further explored for treating depressive and anxiety disorders.

Hydroxypyridinone-Diamine Hybrids as Potential Neuroprotective Agents in the PC12 Cell-Line Model of Alzheimer's Disease

There is an urgent need to propose effective treatments for Alzheimer’s disease (AD). Although the origin of the disease is poorly understood, several therapeutic options have been proposed. The new therapeutic approaches targeting biometal-mediated neurodegenerative pathways appear to be interesting ones. As a continuation of our preceding studies, two novel series of advanced glycation endproducts (AGE)/advanced lipid peroxidation endproducts (ALE) inhibitors have been developed as multifunctional scavengers. This extended work allowed us to highlight the new hydroxypyridinone-diamine hybrid IIa-3 bearing a C4 alkyl linker between the two pharmacophores. This derivative exhibited preserved potent capacities to trap reactive carbonyl species (vicinal diamine function) as well as reactive oxygen species and transition metals (hydroxypyridinone moiety) in comparison with previously described lead compound 1. In addition, its good predicted absorption, distribution, metabolism and excretion (ADME) properties were correlated with a better efficacy to inhibit in vitro methylglyoxal-induced apoptosis in neuronal-like PC12 cells. This new promising agent revealed improved druglikeness and ability to prevent biometal-mediated oxidative and carbonyl stress amplification involved in AD pathogenesis.

Soluble epoxide hydrolase (Ephx2) silencing attenuates the hydrogen peroxide-induced oxidative damage in IEC-6 cells

INTRODUCTION

Oxidative stress can cause intestinal disease. Soluble epoxide hydrolase (sEH, Ephx2) is related to cell apoptosis. The effect of Ephx2 on the H2O2-induced oxidative damage remains unclear. Thus, we aimed to explore the effect of Ephx2 on oxidative damage and the underlying potential mechanism.

MATERIAL AND METHODS

The cell viability was determined using cell counting kit-8 (CCK-8) assay. The reactive oxygen species (ROS), apoptosis, and mitochondrial membrane potential (MMP) were examined using flow cytometry analysis. Commercial kits were applied to respectively determine the lactate dehydrogenase (LDH) leakage, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity. The expressions of target factors were measured by conducting quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot.

RESULTS

We found that knockdown of Ephx2 enhanced the viability of H2O2-treated IEC-6 cells, and that si-Ephx2 reduced the ROS level, MMP loss, and apoptosis in comparison to the H2O2 model group. Knockdown of Ephx2 was found to decrease LDH activity and MDA content, and to improve the SOD activity in comparison to those in the H2O2 model group. Knockdown of Ephx2 reduced the expressions of Fas, Fasl, Bax, and cleavedcaspase-3 and elevated the expression of Bcl-2 in H2O2-treated IEC-6 cells. Furthermore, we observed that knockdown of Ephx2 enhanced the phosphorylation of PI3K, Akt, and GSK3β, which were reduced by the treatment of H2O2. In addition, the anti-apoptotic effect of si-Ephx2 was enhanced in the presence of AUDA-pharmacological Ephx2 inhibitor.

CONCLUSIONS

Ephx2 silencing inhibited H2O2-induced oxidative damage. The PI3K/Akt/GSK3β pathway was related to the effect of si-Ephx2. Our study provided a potential target for the prevention of intestinal injury.

A novel antiviral inhibits Zika virus infection while increasing intracellular glutathione biosynthesis in distinct cell culture models

We investigated the effects of a specific free-form amino acids formulation on Zika virus replication in two different cell culture model systems, one representative of humans and the other of Old World primates from whom Zika virus was first isolated. Here we present data demonstrating that the formulation of the specific free-form amino acid (FFAAP), comprising cystine, glycine, and a glutamate source, along with a minute concentration of selenium inhibited Zika virus replication by up to 90% with an ED₉₀ (effective dose at which 90% of a dose of Zika virus was inhibited) of 2.5 mM in human cells and 4 mM Vero cells. The ED₉₀ concentration of precursors was innocuous for uninfected cells, but resulted in reduced Zika virus replication by up to 90% at 2-5 mM concentrations in nonhuman primate cells and at 1-3 mM concentration in human placental cells. Two important observations were forthcoming: 1) Zika virus production was decreased by up to 90% in Vero and JEG-3 cells treated with FFAAP (ED₉₀ 4.0 mM, and 2.5 mM, respectively) throughout 48-72 h of post infection (hpi) compared to untreated infected cells and 2) Zika virus requires intracellular glutathione for replication in human placental cells, while showing enhanced replication in Vero cells with no glutathione. Relative increases in intracellular glutathione biosynthesis followed FFAAP treatment but blocking intracellular biosynthesis of glutathione in human cells resulted in virus inhibition in human placental cells. The blockade of biosynthesis actually increased Zika virus replication in Vero cells. These findings identify an efficacious inhibitor, FFAAP, of Zika virus replication in both human and nonhuman primate cells, while providing novel insight into the different roles of intracellular glutathione in Zika virus replication.

miR-146a down-regulation alleviates H2O2-induced cytotoxicity of PC12 cells by regulating MCL1/JAK/STAT pathway : miR-146a down-regulation relieves H2O2-induced PC12 cells cytotoxicity by MCL1/JAK/STAT

Oxidative stress and miRNAs have been confirmed to play an important role in neurological diseases. The study aimed to explore the underlying effect and mechanisms of miR-146a in H₂O₂-induced injury of PC12 cells. Here, PC12 cells were stimulated with 200 μM of H₂O₂ to construct oxidative injury model. Cell injury was evaluated on the basis of the changes in cell viability, migration, invasion, apoptosis, and DNA damage. Results revealed that miR-146a expression was up-regulated in H₂O₂-induced PC12 cells. Functional analysis showed that down-regulation of miR-146a alleviated H₂O₂-induced cytotoxicity in PC12 cells. Dual-luciferase reporter and western blot assay verified that MCL1 was a direct target gene of miR-146a. Moreover, anti-miR-146a-mediated suppression on cell cytotoxicity was abated following MCL1 knockdown in H₂O₂-induced PC12 cells. Furthermore, MCL1 activated JAK/STAT signaling pathway and MCL1 overexpression attenuated H₂O₂-induced cytotoxicity in PC12 cells by JAK/STAT signaling pathway. In conclusion, this study suggested that suppression of miR-146a abated H₂O₂-induced cytotoxicity in PC12 cells via regulating MCL1/JAK/STAT pathway.

Up-regulation of FOS-like antigen 1 contributes to neuronal apoptosis in the cortex of rat following traumatic brain injury

Neuronal apoptosis is an important process of secondary brain injury which is induced by neurochemical signaling cascades after traumatic brain injury (TBI). Present study was designed to investigate whether FOS-like antigen 1 (Fra-1) is involved in the neuronal apoptosis. Western blot analysis and immunohistochemistry in a rat TBI model revealed a significant increase in the expression of Fra-1 in the ipsilateral brain cortex, which was in parallel with increase in the expression of active caspase-3. With immunofluorescence double-labeling, Fra-1 was colocalized with active caspase-3 and with NeuN, a neuronal marker. In an in vitro cell injury model, H₂O₂ exposure induced cell apoptosis and reduced cell viability and at the same time, a similar increased expression of active caspase-3, p53 and Fra-1 was found in PC12 cells. Down-regulation of Fra-1 through transfection with Fra-1 siRNA remarkably elevated cell viability, reduced the expression of active caspase-3 and p53, and decreased apoptosis of PC12 cells after H₂O₂ exposure. Taken together, present findings suggest that Fra-1 may be involved in the induction of neuronal apoptosis through up-regulating p53 signaling pathway and that this action may contribute to the secondary neuropathological process after TBI.

Flavonoids of Kudzu Root Fermented by Eurtotium cristatum Protected Rat Pheochromocytoma Line 12 (PC12) Cells against H₂O₂-Induced Apoptosis

Novel bioactive components have greatly attracted attention as they demonstrate health benefits. Reversed-phase high performance liquid chromatography (RP-HPLC) showed that isoflavonoid compounds of kudzu root (Pueraria lobata) fermented by Eurtotium cristatum and extracted using de-ionized water were higher active compared with non-fermented. A model of H₂O₂-inducd cell damage was built using rat pheochromocytoma line 12 (PC12) cell to observe the protective effect of non-fermented kudzu root (Pueraria lobata) (NFK) and fermented kudzu root (Pueraria lobata) (FK). Cell viability and apoptosis were analyzed through inverted microscopy and flow cytometry. The level of lactate dehydrogenase, catalase activity, superoxide dismutase, glutathione, and reactive oxygen species (ROS) were evaluated. Results showed that NFK and FK could significantly protect PC12 cell against damage caused by H₂O₂-induced oxidative stress. The intracellular antioxidant system was increased, protected the cell membrane inhibit H₂O₂-induced apoptosis by scavenging of ROS. Moreover, NFK and FK regulated the cell cycle to prevent cell apoptosis. Isoflavonoid from the kudzu root especially fermented kudzu root with E. cristatum are potentially therapeutic drugs against diseases induced by oxidative damage.

Effect of epigallocatechin-3-gallate on acrylamide-induced oxidative stress and apoptosis in PC12 cells

Acrylamide (ACR) is a chemical intermediate utilized in industry. ACR is also formed during heating of foods containing carbohydrates and amino acids. Therefore, humans are widely exposed to ACR, and ACR neurotoxicity in humans is a significant public health issue attracting wide attention. In this study, we investigated the potential neuroprotective effects of epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic compound in green tea, in PC12 cells treated with ACR. ACR-treated PC12 cells pretreated with various concentrations of EGCG (2.5, 5 and 10 μM) for 24 h had increased viability and acetylcholinesterase activity and reduced apoptosis and necrosis compared to cells exposed to ACR alone. EGCG reduced the expression of bax mRNA, decreased cytochrome c release, reduced intracellular calcium levels, inactivated caspase 3 and increased mitochondrial membrane potential, suggesting that EGCG prevents ACR-induced apoptosis through a mitochondrial-mediated pathway. In addition, EGCG inhibited the formation of reactive oxygen species and lipid peroxidation while enhancing superoxide dismutase activity and glutathione levels, thereby reducing oxidative stress. Our results indicate that pretreatment of PC12 cells with EGCG attenuates ACR-induced apoptosis by reducing oxidative stress. Therefore, drinking green tea may reduce nerve injury induced by ACR.

Multifunctional diamine AGE/ALE inhibitors with potential therapeutical properties against Alzheimer's disease

An important part of pathogenesis of Alzheimer's disease (AD) is attributed to the contribution of AGE (Advanced Glycation Endproducts) and ALE (Advanced Lipid peroxidation Endproducts). In order to attenuate the progression of AD, we designed a new type of molecules that consist of two trapping parts for reactive carbonyl species (RCS) and reactive oxygen species (ROS), precursors of AGE and ALE, respectively. These molecules also chelate transition metals, the promoters of ROS formation. In this paper, synthesis of the new AGE/ALE inhibitors and evaluation of their physicochemical and biological properties (carbonyl trapping capacity, antioxidant activity, Cu(2+)-chelating capacity, cytotoxicity and protective effect against in vitro MGO-induced apoptosis in the model AD cell-line PC12) are described. It is found that compounds 40b and 51e possess promising therapeutic potentials for treating AD.

Methyl-esterified 3-hydroxybutyrate oligomers protect bacteria from hydroxyl radicals

Bacteria rely mainly on enzymes, glutathione and other low-molecular weight thiols to overcome oxidative stress. However, hydroxyl radicals are the most cytotoxic reactive oxygen species, and no known enzymatic system exists for their detoxification. We now show that methyl-esterified dimers and trimers of 3-hydroxybutyrate (ME-3HB), produced by bacteria capable of polyhydroxybutyrate biosynthesis, have 3-fold greater hydroxyl radical-scavenging activity than glutathione and 11-fold higher activity than vitamin C or the monomer 3-hydroxybutyric acid. We found that ME-3HB oligomers protect hypersensitive yeast deletion mutants lacking oxidative stress-response genes from hydroxyl radical stress. Our results show that phaC and phaZ, encoding polymerase and depolymerase, respectively, are activated and polyhydroxybutyrate reserves are degraded for production of ME-3HB oligomers in bacteria infecting plant cells and exposed to hydroxyl radical stress. We found that ME-3HB oligomer production is widespread, especially in bacteria adapted to stressful environments. We discuss how ME-3HB oligomers could provide opportunities for numerous applications in human health.

Cocktail of Four Active Components Derived from Sheng Mai San Inhibits Hydrogen Peroxide-Induced PC12 Cell Apoptosis Linked with the Caspase-3/ROCK1/MLC Pathway

SMXZF, a combination of four active components including ginsenoside Rb1, ginsenoside Rg1, schizandrin, and DT-13 (6:9:5:4) that is derived from Sheng Mai San, has previously been shown to exhibit a neuroprotective effect against focal ischemia/reperfusion injury. Due to the key role of oxidative stress-induced neuronal apoptosis in the pathogenesis of stroke, we examined the effect of SMXZF in oxidative stress responses and related signaling pathways in differentiated pheochromocytoma (PC12) cells. Our results showed that incubation with 100 μM hydrogen peroxide (H2O2) for 12 hr could reduce cell viability and superoxide dismutase (SOD) activity with an increase of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA). In contrast, SMXZF alleviated oxidative stress by reducing the over-production of ROS and MDA in parallel to concentration dependently increasing SOD activity. In addition, SMXZF significantly attenuated H2O2-induced caspase-3 cleavage, Rho-associated coiled-coil-containing protein kinase-1 (ROCK1) activation, and myosin light-chain (MLC) phosphorylation. Inhibiting either caspase-3 or ROCK1 mimicked the effect. Consequently, our results suggest that SMXZF inhibits H2O2-induced neuronal apoptosis linked with the caspase-3/ROCK1/MLC pathway, which has also been confirmed to be a positive feedback loop in oxidative stress-injured PC12 cells. These findings support the pharmacological potential of SMXZF for neurodegenerative diseases and stroke.

Activation of Type 4 Metabotropic Glutamate Receptor Attenuates Oxidative Stress-Induced Death of Neural Stem Cells with Inhibition of JNK and p38 MAPK Signaling

Promoting both endogenous and exogenous neural stem cells' (NSCs) survival in the hostile host environments is essential to cell replacement therapy for central nervous system (CNS) disorders. Type 4 metabotropic glutamate receptor (mGluR4), one of the members of mGluRs, has been shown to protect neurons from acute and chronic excitotoxic insults in various brain damages. The present study investigated the preventive effects of mGluR4 on NSC injury induced by oxidative stress. Under challenge with H2O2, loss of cell viability was observed in cultured rat NSCs, and treatment with selective mGluR4 agonist VU0155041 conferred protective effects against the loss of cellular viability in a concentration-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Pretreatment of VU0155041 (30 μM) also inhibited the excessive NSC death induced by H2O2, and group III mGluRs antagonist (RS)-a-methylserine-O-phosphate (MSOP) or gene-targeted knockdown abolished the protective action of mGluR4, indicated by propidium iodide-Hoechst and terminal deoxynucleotidyl transferase-mediated UTP nick end labeling (TUNEL) staining. Western blot assay demonstrated that mGluR4 activation reversed the decreased procaspase-8/9/3and the destructed Bcl-2/Bax expressing balance, and likewise, MSOP and mGluR4 knockdown abrogated the action of mGluR4 activity. Furthermore, inhibition of JNK and p38 mitogen-activated protein kinases (MAPKs) were observed after mGluR4 activation, and as paralleling control, JNK-specific inhibitor SP600125 and p38-specific inhibitor SB203580 significantly rescued the H2O2-mediated NSC apoptosis and cleavage of procaspase-3. We suggest that activation of mGluR4 prevents oxidative stress-induced NSC death and apoptotic-associated protein activities with involvement of inhibiting the JNK and p38 pathways in cell culture. Our findings may help to develop strategies for enhancing the resided and transplanted NSC survival after oxidative stress insult of CNS.

Beyond the 5-HT3 receptors

Accumulation of reactive oxygen species, such as hydrogen peroxide (H2O2), generated by inflammatory cells or other pathological conditions, leads to oxidative stress, which may contribute to the neuronal degeneration observed in a wide variety of neurodegenerative disorders such as Alzheimer’s disease. Recent investigations have described effective properties of tropisetron, such as antiphlogistic action or protection against β-amyloid induced-neuroinflammation in rats. Our data revealed that H2O2-induced cell death in rat pheochromocytoma cell line (PC12) can be inhibited by tropisetron, as defined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay, caspase 3 and caspase 12 levels. We further showed that tropisetron exerts its protective effects by upregulation of heme oxygenase-1, glutathione, catalase activity, and nuclear factor-erythroid 2 p45-related factor 2 level. Moreover, tropisetron was recently found to be a partial agonist of α7 nicotinic acetylcholine receptor (α7nAChR). The activation of α7nAChR could inhibit inflammatory and apoptotic signaling pathways in the oxidative stress conditions. In this study, selective α7nAChR antagonists (methyllycaconitine) reversed the effects of tropisetron on caspase 3 level. Our findings indicated that tropisetron can protect PC12 cells against H2O2-induced neurotoxicity through α7nAChR in vitro.

Pathway of programmed cell death and oxidative stress induced by β-hydroxybutyrate in dairy cow abomasum smooth muscle cells and in mouse gastric smooth muscle

The administration of exogenous β-hydroxybutyrate (β-HB), as well as fasting and caloric restriction, is a condition associated with β-HB abundance and decreased appetite in animals. Increased β-HB and decreased appetite exist simultaneously in some diseases, such as bovine left displaced abomasums (LDA) and human chronic gastritis. However, the effects of β-HB on stomach injuries have not been explored. To elucidate the possible effects of exogenous β-HB on the stomach, mice were injected intraperitoneally with β-HB, and bovine abomasum smooth muscle cells (BSMCs) were treated with different concentrations of β-HB. We found that β-HB induced BSMCs endoplasmic reticulum- and mitochondria-mediated apoptotic cell death. β-HB promoted Bax expression and caspase-12, -9, and -3 activation while blocking Bcl-2 expression. β-HB also promoted AIF, EndoG release and p53 expression. β-HB acted on key molecules in the apoptotic cell death pathway and increased p38 and c-June NH2-terminal kinase phosphorylation while inhibiting ERK phosphorylation and PCNA expression. β-HB upregulated P27 and P21 mRNA levels while downregulating cyclin and CDK mRNA levels, arresting the cell cycle. These results suggest that BSMCs treated with β-HB can induce oxidative stress, which can be prevented by intracellular calcium chelators BAPTA/AM but not antioxidant NAC. Additionally, these results suggest that β-HB causes ROS generation through a Ca²⁺-dependent mechanism and that intracellular Ca²⁺ levels play a critical role in β-HB -induced apoptotic cell death. The impact of β-HB on programmed cell death and oxidative stress in vivo was confirmed in murine experiments. For the first time, we show oxidative stress effects of β-HB on smooth muscle. We propose that β-HB is a possible cause of some stomach diseases, including bovine LDA.

Energy substrates protect hippocampus against endogenous glutamate-mediated neurodegeneration in awake rats

Excitotoxicity due to excessive glutamatergic neurotransmission is a well-studied phenomenon that has been related to the mechanisms of neuronal death occurring in some disorders of the CNS. We have previously shown that the intrahippocampal perfusion by microdialysis of 4-aminopyridine (4-AP) in rats stimulates endogenous glutamate release from nerve endings and this results in excitotoxic effects such as immediate seizures and delayed neuronal death, due to the overactivation of N-methyl-D-aspartate (NMDA) receptors. To study whether mitochondrial energy dysfunction and oxidative stress could be involved in this 4-AP-induced excitotoxicity, we evaluated in awake rats the protective effect of several energy substrates and antioxidant compounds, using microdialysis, electroencephalographic (EEG) recording and histological analysis. The 4-AP-induced behavioral and EEG seizures, which progressed to status epilepticus in about 30 min, were prevented by the NMDA receptor antagonist MK-801, whereas acetoacetate, DL- and L-β-hydroxybutyrate did not protect against seizures but increased the latency to the onset of status epilepticus; pyruvate, α-ketoglutarate and glutathione ethyl ester did not show any protective effect. 4-AP also produced nearly complete loss of pyramidal neurons in CA1 and CA3 regions of the ipsilateral hippocampus 24 h after the experiment. MK-801 totally prevented this neuronal death and the energy substrates tested protected by about 50%, whereas the antioxidants showed only a weak protection. We conclude that ketone bodies possess weak anticonvulsant effects and that energy metabolism impairment plays a more important role than oxidative stress in the delayed hippocampal neurodegeneration resulting from the excitotoxic action of 4-AP mediated by endogenous glutamate.

3-Hydroxybutyrate methyl ester as a potential drug against Alzheimer's disease via mitochondria protection mechanism

Alzheimer's disease (AD) is induced by many reasons, including decreased cellular utilization of glucose and brain cell mitochondrial damages. Degradation product of microbially synthesized polyhydroxybutyrate (PHB), namely, 3-hydroxybutyrate (3HB), can be an alternative to glucose during sustained hypoglycemia. In this study, the derivative of 3HB, 3-hydroxybutyrate methyl ester (HBME), was used by cells as an alternative to glucose. HBME inhibited cell apoptosis under glucose deprivation, rescued activities of mitochondrial respiratory chain complexes that were impaired in AD patients and decreased the generation of ROS. Meanwhile, HBME stabilized the mitochondrial membrane potential. In vivo studies showed that HBME crossed the blood brain barrier easier compared with charged 3HB, resulting in a better bioavailability. AD mice treated with HBME performed significantly better (p < 0.05) in the Morris water maze compared with other groups, demonstrating that HBME has a positive in vivo pharmaceutical effect to improve the spatial learning and working memory of mice. A reduced amyloid-β deposition in mouse brains after intragastric administration of HBME was also observed. Combined with the in vitro and in vivo results, HBME was proposed to be a drug candidate against AD, its working mechanism appeared to be mediated by various effects of protecting mitochondrial damages.

The role of oxidative stress in Parkinson's disease

Oxidative stress plays an important role in the degeneration of dopaminergic neurons in Parkinson's disease (PD). Disruptions in the physiologic maintenance of the redox potential in neurons interfere with several biological processes, ultimately leading to cell death. Evidence has been developed for oxidative and nitrative damage to key cellular components in the PD substantia nigra. A number of sources and mechanisms for the generation of reactive oxygen species (ROS) are recognized including the metabolism of dopamine itself, mitochondrial dysfunction, iron, neuroinflammatory cells, calcium, and aging. PD causing gene products including DJ-1, PINK1, parkin, alpha-synuclein and LRRK2 also impact in complex ways mitochondrial function leading to exacerbation of ROS generation and susceptibility to oxidative stress. Additionally, cellular homeostatic processes including the ubiquitin-proteasome system and mitophagy are impacted by oxidative stress. It is apparent that the interplay between these various mechanisms contributes to neurodegeneration in PD as a feed forward scenario where primary insults lead to oxidative stress, which damages key cellular pathogenetic proteins that in turn cause more ROS production. Animal models of PD have yielded some insights into the molecular pathways of neuronal degeneration and highlighted previously unknown mechanisms by which oxidative stress contributes to PD. However, therapeutic attempts to target the general state of oxidative stress in clinical trials have failed to demonstrate an impact on disease progression. Recent knowledge gained about the specific mechanisms related to PD gene products that modulate ROS production and the response of neurons to stress may provide targeted new approaches towards neuroprotection.