Fumaric acid esters promote neuronal survival upon ischemic stress through activation of the Nrf2 but not HIF-1 signaling pathway

Metabolic Reprogramming in Gliocyte Post-cerebral Ischemia/ Reperfusion: From Pathophysiology to Therapeutic Potential

Ischemic stroke is a leading cause of disability and death worldwide. However, the clinical efficacy of recanalization therapy as a preferred option is significantly hindered by reperfusion injury. The transformation between different phenotypes of gliocytes is closely associated with cerebral ischemia/ reperfusion injury (CI/RI). Moreover, gliocyte polarization induces metabolic reprogramming, which refers to the shift in gliocyte phenotype and the overall transformation of the metabolic network to compensate for energy demand and building block requirements during CI/RI caused by hypoxia, energy deficiency, and oxidative stress. Within microglia, the pro-inflammatory phenotype exhibits upregulated glycolysis, pentose phosphate pathway, fatty acid synthesis, and glutamine synthesis, whereas the anti-inflammatory phenotype demonstrates enhanced mitochondrial oxidative phosphorylation and fatty acid oxidation. Reactive astrocytes display increased glycolysis but impaired glycogenolysis and reduced glutamate uptake after CI/RI. There is mounting evidence suggesting that manipulation of energy metabolism homeostasis can induce microglial cells and astrocytes to switch from neurotoxic to neuroprotective phenotypes. A comprehensive understanding of underlying mechanisms and manipulation strategies targeting metabolic pathways could potentially enable gliocytes to be reprogrammed toward beneficial functions while opening new therapeutic avenues for CI/RI treatment. This review provides an overview of current insights into metabolic reprogramming mechanisms in microglia and astrocytes within the pathophysiological context of CI/RI, along with potential pharmacological targets. Herein, we emphasize the potential of metabolic reprogramming of gliocytes as a therapeutic target for CI/RI and aim to offer a novel perspective in the treatment of CI/RI.

Neuronal Responses to Ischemia: Scoping Review of Insights from Human-Derived In Vitro Models

Translation of neuroprotective treatment effects from experimental animal models to patients with cerebral ischemia has been challenging. Since pathophysiological processes may vary across species, an experimental model to clarify human-specific neuronal pathomechanisms may help. We conducted a scoping review of the literature on human neuronal in vitro models that have been used to study neuronal responses to ischemia or hypoxia, the parts of the pathophysiological cascade that have been investigated in those models, and evidence on effects of interventions. We included 147 studies on four different human neuronal models. The majority of the studies (132/147) was conducted in SH-SY5Y cells, which is a cancerous cell line derived from a single neuroblastoma patient. Of these, 119/132 used undifferentiated SH-SY5Y cells, that lack many neuronal characteristics. Two studies used healthy human induced pluripotent stem cell derived neuronal networks. Most studies used microscopic measures and established hypoxia induced cell death, oxidative stress, or inflammation. Only one study investigated the effect of hypoxia on neuronal network functionality using micro-electrode arrays. Treatment targets included oxidative stress, inflammation, cell death, and neuronal network stimulation. We discuss (dis)advantages of the various model systems and propose future perspectives for research into human neuronal responses to ischemia or hypoxia.

Mechanism of action and therapeutic potential of dimethyl fumarate in ischemic stroke

Dimethyl fumarate (DMF) is an immunomodulatory drug currently approved for the treatment of multiple sclerosis and psoriasis. Its benefits on ischemic stroke outcomes have recently come to attention. To date, only tissue plasminogen activators (tPAs) and clot retrieval methods have been approved by the FDA for the treatment of ischemic stroke. Ischemic conditions lead to inflammation through diverse mechanisms, and recanalization can worsen the state. DMF and the nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway it regulates seem to be important in postischemic inflammation, and animal studies have demonstrated that the drug improves overall stroke outcomes. Although the exact mechanism is still unknown, studies indicate that these beneficial impacts are due to the modulation of immune responses, blood-brain barrier permeability, and hemodynamic adjustments. One major component evaluated before, during, and after tPA therapy in stroke patients is blood pressure (BP). Recent studies have found that DMF may impact BP. Both hypotension and hypertension need correction before treatment, which may delay the appropriate intervention. Since BP management is crucial in managing stroke patients, it is important to consider DMF's role in this matter. That being said, it seems further investigations on DMF may lead to an alternative approach for stroke patients. In this article, we discuss the mechanistic roles of DMF and its potential role in stroke based on previously published literature and laboratory findings.

Response to fumaric acid esters for plaque type psoriasis in real-world practice is largely independent of patient characteristics at baseline - a multivariable regression analysis from the German psoriasis registry PsoBest

OBJECTIVES

Fumaric acid esters (FAEs) are a well-established treatment option for long-term therapy of moderate to severe plaque psoriasis. This study examines effectiveness of FAEs for the treatment of plaque psoriasis in real-world practice at 12 months and if patient characteristics affect the odds of clinical response.

METHODS

A descriptive, multivariable logistic regression analysis was conducted in a cohort drawn from the German registry PsoBest. Baseline patient characteristics were assessed as potential treatment effect modifiers.

RESULTS

444 patients (mean age 47.0 years, 39.0% female) were eligible for response analysis using nonresponder imputation at month 12. Of these, 39.6% achieved clinical response, i.e., Psoriasis Area and Severity Index (PASI) ≤3 or skin clearance. In logistic regression analysis (R² = 0.114), only baseline PASI was a significant factor: patients with PASI <10 had a 4 times higher odds (p ≤ 0.001, OR 4.088), patients with PASI of 10-20 a twofold higher odds of response (p ≤ 0.044, OR 1.961) compared to those with PASI >20. Neither sex, age, body weight, disease duration, comorbidity nor pre-treatment had an impact on the odds of response (p > 0.05).

CONCLUSIONS

FAEs showed a favorable response at 12 months, largely independent of patient characteristics.

An update of Nrf2 activators and inhibitors in cancer prevention/promotion

NF-E2-related factor 2 (Nrf2) protein is a basic-region leucine zipper transcription factor that defends against endogenous or exogenous stressors. By inducing several cytoprotective and detoxifying gene expressions, Nrf2 can increase the sensitivity of the cells to oxidants and electrophiles. Transient Nrf2 activation, by its specific activators, has protective roles against carcinogenesis and cancer development. However, permanent activation of Nrf2 promotes various cancer properties, comprising malignant progression, chemo/radio resistance, and poor patient prognosis. Taken together, these findings suggest that reaching an optimal balance between paradoxical functions of Nrf2 in malignancy may render a selective improvement to identify therapeutic strategies in cancer treatment. In this review, we describe lately discovered Nrf2 inducers and inhibitors, and their chemopreventive and/or anticancer activities.

The Nrf2 pathway signifies one of the most significant cell defense procedures against exogenous or endogenous stressors. Certainly, by increasing the expression of several cytoprotective genes, the transcription factor Nrf2 can shelter cells and tissues from multiple sources of damage including electrophilic, xenobiotic, metabolic, and oxidative stress. Notably, the aberrant activation or accumulation of Nrf2, a common event in many tumors, confers a selective advantage to cancer cells and is connected to malignant progression, therapy resistance, and poor prognosis. Therefore, lately, Nrf2 has arisen as a hopeful target in treatment of cancer, and many struggles have been made to detect therapeutic strategies intended at disrupting its pro-oncogenic role. By summarizing the outcomes from past and recent studies, this review provided an overview concerning the Nrf2 pathway and the molecular mechanisms causing Nrf2 hyperactivation in cancer cells. Finally, this paper also described some of the most promising therapeutic approaches that have been successfully employed to counteract Nrf2 activity in tumors, with a particular emphasis on the development of natural compounds and the adoption of drug repurposing strategies.

Repurposing Dimethyl Fumarate for Cardiovascular Diseases: Pharmacological Effects, Molecular Mechanisms, and Therapeutic Promise

Dimethyl fumarate (DMF) is a small molecule that has been shown to assert potent in vivo immunoregulatory and anti-inflammatory therapeutic actions. The drug has been approved and is currently in use for treating multiple sclerosis and psoriasis in the USA and Europe. Since inflammatory reactions have been significantly implicated in the etiology and progression of diverse disease states, the pharmacological actions of DMF are presently being explored and generalized to other diseases where inflammation needs to be suppressed and immunoregulation is desirable, either as a monotherapeutic agent or as an adjuvant. In this review, we focus on DMF, and present an overview of its mechanism of action while briefly discussing its pharmacokinetic profile. We further discuss in detail its pharmacological uses and highlight its potential applications in the treatment of cardiovascular diseases. DMF, with its unique combination of anti-inflammatory and vasculoprotective effects, has the potential to be repurposed as a therapeutic agent in patients with atherosclerotic cardiovascular disease. The clinical studies mentioned in this review with respect to the beneficial effects of DMF in atherosclerosis involve observations in patients with multiple sclerosis and psoriasis in small cohorts and for short durations. The findings of these studies need to be assessed in larger prospective clinical trials, ideally with a double-blind randomized study design, investigating the effects on cardiovascular endpoints as well as morbidity and mortality. The long-term impact of DMF therapy on cardiovascular diseases also needs to be confirmed.

The Nrf2 Pathway in Ischemic Stroke: A Review

Ischemic stroke, characterized by the sudden loss of blood flow in specific area(s) of the brain, is the leading cause of permanent disability and is among the leading causes of death worldwide. The only approved pharmacological treatment for acute ischemic stroke (intravenous thrombolysis with recombinant tissue plasminogen activator) has significant clinical limitations and does not consider the complex set of events taking place after the onset of ischemic stroke (ischemic cascade), which is characterized by significant pro-oxidative events. The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of a great number of antioxidant and/or defense proteins, has been pointed as a potential pharmacological target involved in the mitigation of deleterious oxidative events taking place at the ischemic cascade. This review summarizes studies concerning the protective role of Nrf2 in experimental models of ischemic stroke, emphasizing molecular events resulting from ischemic stroke that are, in parallel, modulated by Nrf2. Considering the acute nature of ischemic stroke, we discuss the challenges in using a putative pharmacological strategy (Nrf2 activator) that relies upon transcription, translation and metabolically active cells in treating ischemic stroke patients.

Systematic Elucidation of the Mechanism of Sappan Lignum in the Treatment of Diabetic Peripheral Neuropathy Based on Network Pharmacology

Background

Diabetic peripheral neuropathy (DPN) is one of the most common chronic complications of diabetes, which seriously affects the physical and mental health of patients. Sappan Lignum (SL) is effective in treating DPN. Previous reports have shown that SL has a clear hypoglycemic and anti-inflammatory effect. However, the study of SL in the treatment of DPN is still limited and rare.

Objective

To investigate the mechanism of SL in the treatment of DPN based on network pharmacology.

Methods

The active ingredients of SL were screened by related databases. The compound targets were collected by the target prediction platforms. The DPN-related targets were gathered through disease databases. The intersection targets were obtained by uploading the compound targets and disease targets to Venny 2.1.0, and a compound-target network was constructed by Cytoscape3.7.2. The protein-protein interaction (PPI) relationships were obtained by the STRING11.0 database. Genome Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed using the DAVID6.8 database. Molecular docking of key compounds and core targets was performed by DockThor.

Results

A total of 29 compounds and 51 intersection targets with potential therapeutic effects on DPN were obtained. The compound-target network construction resulted in four key compounds: protostemonine, 3-deoxysappanchalcone, 7,3′,4′-trihydroxy-3-benzyl-2H-chromene, and o-12′-methylergocornine. PPI network analysis yielded 10 core targets: AKT1, MAPK3, CXCL8, TNF, OPRM1, MTOR, STAT3, MAPK8, SIRT1, and HSP90AA1. KEGG analysis resulted in 82 signaling pathways (P < 0.05), including insulin resistance, HIF-1 signaling pathway, and type II diabetes. The docking results indicated that the main active compounds could stably bind to core targets.

Conclusion

SL had the mechanism of multiple ingredients, multiple targets, and multiple pathways in the treatment of DPN. This study provided a scientific basis for further research on the treatment of DPN with SL and its extracts.

Notoginseng Leaf Triterpenes Ameliorates OGD/R-Induced Neuronal Injury via SIRT1/2/3-Foxo3a-MnSOD/PGC-1α Signaling Pathways Mediated by the NAMPT-NAD Pathway

Background

Cerebral ischemic stroke (CIS) is a common cerebrovascular disease whose main risks include necrosis, apoptosis, and cerebral infarction. But few therapeutic advances and prominent drugs seem to be of value for ischemic stroke in the clinic yet. In the previous study, notoginseng leaf triterpenes (PNGL) from Panax notoginseng stem and leaf have been confirmed to have neuroprotective effects against mitochondrial damages caused by cerebral ischemia in vivo. However, the potential mechanisms of mitochondrial protection have not been fully elaborated yet.

Methods

The oxygen and glucose deprivation and reperfusion (OGD/R)-induced SH-SY5Y cells were adopted to explore the neuroprotective effects and the potential mechanisms of PNGL in vitro. Cellular cytotoxicity was measured by MTT, viable mitochondrial staining, and antioxidant marker detection in vitro.Mitochondrial functions were analyzed by ATP content measurement, MMP determination, ROS, NAD, and NADH kit in vitro. And the inhibitor FK866 was adopted to verify the regulation of PNGL on the target NAMPT and its key downstream.

Results

In OGD/R models, treatment with PNGL strikingly alleviated ischemia injury, obviously preserved redox balance and excessive oxidative stress, inhibited mitochondrial damage, markedly alleviated energy metabolism dysfunction, improved neuronal mitochondrial functions, obviously reduced neuronal loss and apoptosis in vitro, and thus notedly raised neuronal survival under ischemia and hypoxia. Meanwhile, PNGL markedly increased the expression of nicotinamide phosphoribosyltransferase (NAMPT) in the ischemic regions and OGD/R-induced SH-SY5Y cells and regulated the downstream SIRT1/2-Foxo3a and SIRT1/3-MnSOD/PGC-1α pathways. And FK866 further verified that the protective effects of PNGL might be mediated by the NAMPT in vitro.

Conclusions

The mitochondrial protective effects of PNGL are, at least partly, mediated via the NAMPT-NAD+ and its downstream SIRT1/2/3-Foxo3a-MnSOD/PGC-1α signaling pathways. PNGL, as a new drug candidate, has a pivotal role in mitochondrial homeostasis and energy metabolism therapy via NAMPT against OGD-induced SH-SY5Y cell injury.

Nephroprotective Effect of Pleurotus ostreatus and Agaricus bisporus Extracts and Carvedilol on Ethylene Glycol-Induced Urolithiasis: Roles of NF-κB, p53, Bcl-2, Bax and Bak

This study was designed to assess the nephroprotective effects of Pleurotus ostreatus and Agaricus bisporus aqueous extracts and carvedilol on hyperoxaluria-induced urolithiasis and to scrutinize the possible roles of NF-κB, p53, Bcl-2, Bax and Bak. Phytochemical screening and GC-MS analysis of mushrooms’ aqueous extracts were also performed and revealed the presence of multiple antioxidant and anti-inflammatory components. Hyperoxaluria was induced in Wistar rats through the addition of 0.75% (v/v) ethylene glycol in drinking water for nine weeks. The ethylene glycol-administered rats were orally treated with Pleurotus ostreatus and Agaricus bisporus aqueous extracts (100 mg/kg) and carvedilol (30 mg/kg) daily during the last seven weeks. The study showed that Pleurotus ostreatus, Agaricus bisporus and carvedilol all successfully inhibited ethylene glycol-induced histological perturbations and the elevation of serum creatinine, serum urea, serum and urinary uric acid, serum, urinary and kidney oxalate, urine specific gravity, kidney calcium, kidney NF-κB, NF-κB p65, NF-κB p50, p53, Bax and Bak expressions as well as serum TNF-α and IL-1β levels. Moreover, the treatment decreased the reduction in urinary creatinine, urinary urea, ratios of urinary creatinine to serum creatinine and urinary urea to serum urea, Fex Urea and Bcl-2 expression in kidney. In conclusion, although Pleurotus ostreatus and Agaricus bisporus extracts and carvedilol all significantly inhibited the progression of nephrolithiasis and showed nephroprotective effects against ethylene glycol-induced kidney dysfunction, Pleurotus ostreatus and Agaricus bisporus seemed to be more effective than carvedilol. Moreover, the nephroprotective effects may be mediated via affecting NF-κB activation, extrinsic apoptosis and intrinsic apoptosis pathways.

Exploring the Use of Dimethyl Fumarate as Microglia Modulator for Neurodegenerative Diseases Treatment

The maintenance of redox homeostasis in the brain is critical for the prevention of the development of neurodegenerative diseases. Drugs acting on brain redox balance can be promising for the treatment of neurodegeneration. For more than four decades, dimethyl fumarate (DMF) and other derivatives of fumaric acid ester compounds have been shown to mitigate a number of pathological mechanisms associated with psoriasis and relapsing forms of multiple sclerosis (MS). Recently, DMF has been shown to exert a neuroprotective effect on the central nervous system (CNS), possibly through the modulation of microglia detrimental actions, observed also in multiple brain injuries. In addition to the hypothesis that DMF is linked to the activation of NRF2 and NF-kB transcription factors, the neuroprotective action of DMF may be mediated by the activation of the glutathione (GSH) antioxidant pathway and the regulation of brain iron homeostasis. This review will focus on the role of DMF as an antioxidant modulator in microglia processes and on its mechanisms of action in the modulation of different pathways to attenuate neurodegenerative disease progression.

Serum metabolite profiling of ST-segment elevation myocardial infarction using liquid chromatography quadrupole time-of-flight mass spectrometry

ST segment elevation myocardial infarction (STEMI) is one of the most common global causes of cardiovascular disease-related death. Several metabolites may change during STEMI. Hence, analysis of metabolites in body fluid may be considered as a rapid and accurate test for initial diagnosis. This study has therefore attempted to determine the variation in metabolites identified in the serum of STEMI patients (n = 20) and 15 controls. Samples collected from the Cardiology Department, Medical Faculty, Ataturk University, were extracted by liquid-liquid extraction and analysed using liquid chromatography quadrupole time-of-flight mass spectrometry. The METLIN database was used for the identification and characterization of metabolites. According to Q-TOF/MS measurements, 231 m/z values, which were significantly different between groups (P < 0.01 and fold analysis >1.5) were detected. Metabolite identification was achieved via the Human Metabolome database. According to the multivariate data analysis, leucine, isoleucine, l-proline, l-alanine, glycine, fumaric acid, citrate, succinate and carnitine levels were decreased, whereas levels of propionic acid, maleic acid, butyric acid, urea, oleic acid, palmitic acid, lysoPC [18:2(9Z)], glycerol, phoshpatidylethanolamine, caffeine and l-lactic acid were increased in STEMI patients compared with controls. In conclusion, malonic acid, maleic acid, fumaric acid and palmitic acid can be used as biomarkers for early risk stratification of patients with STEMI.

The neuronal oxygen-sensing pathway controls postnatal vascularization of the murine brain

The contribution of neurons to growth and refinement of the microvasculature during postnatal brain development is only partially understood. Tissue hypoxia is the physiologic stimulus for angiogenesis by enhancing angiogenic mediators partly through activation of hypoxia-inducible factors (HIFs). Hence, we investigated the HIF oxygen-sensing pathway in postmitotic neurons for physiologic angiogenesis in the murine forebrain during postnatal development by using mice lacking the HIF suppressing enzyme prolyl-4-hydroxylase domain (PHD)2 and/or HIF-1/2α in postmitotic neurons. Perinatal activation or inactivation of the HIF pathway in neurons inversely modulated brain vascularization, including endothelial cell number and proliferation, density of total and perfused microvessels, and vascular branching. Accordingly, several angiogenesis-related genes were up-regulated in vivo and in primary neurons derived from PHD2-deficient mice. Among them, only VEGF and adrenomedullin (Adm) promoted angiogenic sprouting of brain endothelial cells. VEGF and Adm additively enhanced endothelial sprouting through activation of multiple pathways. PHD2 deficiency in neurons caused HIF-α stabilization and increased VEGF mRNA levels not only in neurons but unexpectedly also in astrocytes, suggesting a new mechanism of neuron-to-astrocyte signaling. Collectively, our results identify the PHD-HIF pathway in neurons as an important determinant for vascularization of the brain during postnatal development.-Nasyrov, E., Nolan, K. A., Wenger, R. H., Marti, H. H., Kunze, R. The neuronal oxygen-sensing pathway controls postnatal vascularization of the murine brain.

Dual Effects of Chinese Herbal Medicines on Angiogenesis in Cancer and Ischemic Stroke Treatments: Role of HIF-1 Network

Hypoxia-inducible factor-1 (HIF-1)–induced angiogenesis has been involved in numerous pathological conditions, and it may be harmful or beneficial depending on the types of diseases. Exploration on angiogenesis has sparked hopes in providing novel therapeutic approaches on multiple diseases with high mortality rates, such as cancer and ischemic stroke. The HIF-1 pathway is considered to be a major regulator of angiogenesis. HIF-1 seems to be involved in the vascular formation process by synergistic correlations with other proangiogenic factors in cancer and cerebrovascular disease. The regulation of HIF-1–dependent angiogenesis is related to the modulation of HIF-1 bioactivity by regulating HIF-1α transcription or protein translation, HIF-1α DNA binding, HIF-1α and HIF-1α dimerization, and HIF-1 degradation. Traditional Chinese herbal medicines have a long history of clinical use in both cancer and stroke treatments in Asia. Growing evidence has demonstrated potential proangiogenic benefits of Chinese herbal medicines in ischemic stroke, whereas tumor angiogenesis could be inhibited by the active components in Chinese herbal medicines. The objective of this review is to provide comprehensive insight on the effects of Chinese herbal medicines on angiogenesis by regulating HIF-1 pathways in both cancer and ischemic stroke.

Dimethyl fumarate, a two-edged drug: Current status and future directions

Dimethyl fumarate (DMF) is a fumaric acid ester registered for the treatment of relapsing-remitting multiple sclerosis (RRMS). It induces protein succination leading to inactivation of cysteine-rich proteins. It was first shown to possess cytoprotective and antioxidant effects in noncancer models, which appeared related to the induction of the nuclear factor erythroid 2 (NF-E2)-related factor 2 (NRF2) pathway. DMF also displays antitumor activity in several cellular and mice models. Recently, we showed that the anticancer mechanism of DMF is dose-dependent and is paradoxically related to the decrease in the nuclear translocation of NRF2. Some other studies performed indicate also the potential role of DMF in cancers, which are dependent on the NRF2 antioxidant and cellular detoxification program, such as KRAS-mutated lung adenocarcinoma. It, however, seems that DMF has multiple biological effects as it has been shown to also inhibit the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), thus blocking downstream targets that may be involved in the development and progression of inflammatory cascades leading to various disease processes, including tumors, lymphomas, diabetic retinopathy, arthritis, and psoriasis. Herein, we present the current status and future directions of the use of DMF in various diseases models with particular emphases on its targeting of specific intracellular signal transduction cascades in cancer; to shed some light on its possible mode of action.

Dimethyl fumarate up-regulates expression of major neurotrophic factors in the epidermal neural crest stem cells

There is an agreement that combining treatments can lead to substantial improvement, therefore the present study assessed the effects of different concentrations of dimethyl fumarate (DMF) on viability of epidermal neural crest stem cells (EPI-NCSCs). In addition, this investigation was designed to evaluate the effects of DMF on relative expression of major trophic factors mainly the ones with neurotrophic effects, expressed in EPI-NCSCs in order to enhance their therapeutic potential. To determine the appropriate concentration of DMF for EPI-NCSCs treatment, the MTT assay was employed and based on the obtained data, EPI-NCSCs treated with 10μM DMF for 6, 24, 72 or 168 h. In each time point, quantitative RT-PCR technique was used to evaluate NGF, NT-3, BDNF, GDNF and VEGF transcripts. The acquired data showed that 10μM DMF significantly increased the mRNA expression of NGF, NT-3 and BDNF, 72 h following treatment; however, DMF inhibitory effect on GDNF mRNA expression was observed in various time points. No significant changes were detected for VEGF transcript. Our findings reveled that expression of major neurotrophic factors were up-regulated by dimethyl fumarate treatment. Therefore, combining EPI-NCSCs with DMF treatment might be a valuable strategy to improve their therapeutic functions in vivo.

Fumaric acid: production and separation

Fumaric acid is a valuable compound used in foods, beverages, detergents, animal feed, pharmaceuticals and miscellaneous industrial products. It is produced on a large scale by the petrochemical route but the current tendency is towards implementing "green production" and environmental friendly technologies like biotechnological production of fumaric acid using low-cost raw materials. In this context, numerous studies focus on improving the fermentation process not only by using renewable raw material and genetically modified microorganisms, but also by developing and applying different downstream techniques for easy recovery of fumaric acid from the fermented broth. This review presents the main methods for production and separation of fumaric acid, highlighting the advantages and disadvantages of these and the potential economic impact in industry.

ETS-domain containing protein (Elk1) suppression protects cortical neurons against oxygen-glucose deprivation injury

ETS-domain containing protein (Elk1), which is a transcription factor, is reported to be closely related to the apoptosis of primary neurons and could be activated by hypoxia in human microvascular endothelial cells. In this study, we aimed to investigate the role of Elk1 in cortical neurons under oxygen-glucose deprivation (OGD) conditions. The OGD model of cortical neurons was established the anoxia/hypoglycemia-induced injury and the in vivo model was established by middle cerebral artery occlusion (MCAO). Elk1 mRNA and protein expression was significantly up-regulated in neurons exposed to OGD for 24 h, and mRNA expression was also markedly increased in cerebral cortex of rats with MCAO after 10 days. The knockdown of Elk1 in neurons without OGD obviously constrained Fra-1 and promoted Nrf2 expression. Also, Elk1 inhibition suppressed neuronal apoptosis, caspase-3 activity, LDH leakage, and MDA and SOD contents, while it increased cell viability in the neurons with OGD. The overexpression of Fra-1 showed a reverse effect on caspase-3 activity, cell viability and SOD contents in neurons under OGD conditions compared with Elk1 knockdown. Thus, Elk1 inhibition has a protective effect on neurons against OGD-induced injury.

Multiple mechanisms of dimethyl fumarate in amyloid β-induced neurotoxicity in human neuronal cells

Alzheimer disease (AD) is characterized by a complex heterogeneity of pathological changes, and any therapeutic approach categorically requires a multi-targeted way. It has been demonstrated that together with the hallmarks of the disease such as neurofibrillary tangles and senile plaques, oxidative and inflammatory stress covered an important role. Dimethyl fumarate (DMF) is an orally bioavailable methyl ester of fumaric acid and activator of Nrf2 with potential neuroprotective and immunomodulating activities. Therefore, the aim of the present work was to evaluate the potential beneficial effects of DMF, compared with its active metabolite monomethyl fumarate (MMF) (both at 30 μM) in an in vitro Alzheimer's model using SH-SY5Y human neuroblastoma cell lines stimulated with amyloid-beta (Aβ). Moreover, the effect of DMF, compared with MMF, was evaluate by an ex vivo model using organotypic hippocampal slice cultures stimulated with Aβ1-42 (1 μg/ml), to better understand its action in a pathological setting. In both models, DMF pre-treatment (30 μM) preserved cellular viability from Aβ stimulation, reducing tau hyper-phosphorylation, much more efficiently then MMF (30 μM). Moreover, DMF was able to induce an activation of manganese superoxide dismutase (MnSOD) and heme-oxygenase-1 (HO-1), decreasing the severity of oxidative stress. Our results showed important multi-protective effects of DMF pre-treatment from Aβ stimulation both in in vitro and ex vivo models, highlighting an Nrf2/NF-κB-dependent mechanism, which could provide a valuable support to the therapies for neurodegenerative diseases today.

Hibiscus sabdariffa L. as a source of nutrients, bioactive compounds and colouring agents

The nutritional and bioactive composition of plants have aroused much interest not only among scientists, but also in people's daily lives. Apart from the health benefits, plants are a source of pigments that can be used as natural food colorants. In this work, the nutritional composition of Hibiscus sabdariffa L. was analysed, as well as its bioactive compounds and natural pigments. Glucose (sugar), malic acid (organic acid), α-tocopherol (tocopherol) and linoleic acid (fatty acid) were the major constituents in the corresponding classes. 5-(Hydroxymethyl) furfural was the most abundant non-anthocyanin compound, while delphinidin-3-O-sambubioside was the major anthocyanin both in its hydroethanolic extract and infusion. H. sabdariffa extracts showed antioxidant and antimicrobial activities, highlighting that the hydroethanol extract presents not only lipid peroxidation inhibition capacity, but also bactericidal/fungicidal inhibition ability for all the bacteria and fungi tested. Furthermore, both extracts revealed the absence of toxicity using porcine primary liver cells. The studied plant species was thus not only interesting for nutritional purposes but also for bioactive and colouring applications in food, cosmetic and pharmaceutical industries.

Hypoxia-inducible factor-1 alpha is involved in RIP-induced necroptosis caused by in vitro and in vivo ischemic brain injury

Necroptosis, a novel type of programmed cell death, is involved in stroke-induced ischemic brain injury. Although studies have sought to explore the mechanisms of necroptosis, its signaling pathway has not yet to be completely elucidated. Thus, we used oxygen-glucose deprivation (OGD) and middle cerebral artery occlusion (MCAO) models mimicking ischemic stroke (IS) conditions to investigate mechanisms of necroptosis. We found that OGD and MCAO induced cell death, local brain ischemia and neurological deficit, while zVAD-fmk (zVAD, an apoptotic inhibitor), GSK’872 (a receptor interacting protein kinase-3 (RIP3) inhibitor), and combined treatment alleviated cell death and ischemic brain injury. Moreover, OGD and MCAO upregulated protein expression of the triggers of necroptosis: receptor interacting protein kinase-1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL). The upregulation of these proteins was inhibited by GSK’872, combination treatments and RIP3 siRNA but not zVAD treatment. Intriguingly, hypoxia-inducible factor-1 alpha (HIF-1α), an important transcriptional factor under hypoxic conditions, was upregulated by OGD and MCAO. Similar to their inhibitory effects on aforementioned proteins upregulation, GSK’872, combination treatments and RIP3 siRNA decreased HIF-1α protein level. These findings indicate that necroptosis contributes to ischemic brain injury induced by OGD and MCAO and implicate HIF-1α, RIP1, RIP3, and MLKL in necroptosis.

Fumarate modulates the immune/inflammatory response and rescues nerve cells and neurological function after stroke in rats

BACKGROUND

Dimethyl fumarate (DMF), working via its metabolite monomethylfumarate (MMF), acts as a potent antioxidant and immunomodulator in animal models of neurologic disease and in patients with multiple sclerosis. These properties and their translational potential led us to investigate whether DMF/MMF could also protect at-risk and/or dying neurons in models of ischemic stroke in vitro and in vivo. Although the antioxidant effects have been partially addressed, the benefits of DMF immunomodulation after ischemic stroke still need to be explored.

METHODS

In vitro neuronal culture with oxygen-glucose deprivation and rats with middle cerebral artery occlusion were subjected to DMF/MMF treatment. Live/dead cell counting and LDH assay, as well as behavioral deficits, plasma cytokine assay, western blots, real-time PCR (Q-PCR) and immunofluorescence staining, were used to evaluate the mechanisms and neurological outcomes.

RESULTS

We found that MMF significantly rescued cortical neurons from oxygen-glucose deprivation (OGD) in culture and suppressed pro-inflammatory cytokines produced by primary mixed neuron/glia cultures subjected to OGD. In rats, DMF treatment significantly decreased infarction volume by nearly 40 % and significantly improved neurobehavioral deficits after middle cerebral artery occlusion (MCAO). In the acute early phase (72 h after MCAO), DMF induced the expression of transcription factor Nrf2 and its downstream mediator HO-1, important for the protection of infarcted cells against oxidative stress. In addition to its antioxidant role, DMF also acted as a potent immunomodulator, reducing the infiltration of neutrophils and T cells and the number of activated microglia/macrophages in the infarct region by more than 50 % by 7-14 days after MCAO. Concomitantly, the levels of potentially harmful pro-inflammatory cytokines were greatly reduced in the plasma and brain and in OGD neuron/glia cultures.

CONCLUSIONS

We conclude that DMF is neuroprotective in experimental stroke because of its potent immunomodulatory and antioxidant effects and thus may be useful as a novel therapeutic agent to treat stroke in patients.

Panax notoginseng saponins provide neuroprotection by regulating NgR1/RhoA/ROCK2 pathway expression, in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng saponins (PNS) extracted from a traditional Chinese herbal medicine, Panax notoginseng (Burkill) F.H. Chen (Araliaceae), which has been extensively used in treating coronary heart disease, ischemic cerebrovascular disease and hemorrhagic disorders in China over hundreds of years.

AIMS OF THE STUDY

This study explored whether panax notoginseng saponins (PNS) provided neuroprotective effects by inhibiting the expressions of NgR1, RhoA, and ROCK2 following middle cerebral artery occlusion in rats and oxygen-glucose deprivation/reoxygenation (OGD/R) injury in SH-SY5Y cells.

MATERIALS AND METHODS

2,3,5-Triphenyltetrazolium chloride staining was used to determine successful middle cerebral artery occlusion establishment in sham-operated and operated Sprague-Dawley rats 1 day after injury. The rats were randomly separated into sham, model, NEP1-40, PNS, and NEP1-40 plus PNS (N+P) groups. After 7 days of treatment, body mass and neurological deficit scores were analyzed. Tissues were harvested and analyzed by hematoxylin-eosin staining and immunohistochemical analysis, western blotting, and quantitative real-time PCR (qRT-PCR). The optimal drug concentration of NEP1-40 and PNS on SH-SY5Y cells exposed to OGD/R injury was determined by CCK8 analysis. qRT-PCR was used to measure mRNA expression profiles of NgR1, RhoA, and ROCK2 in SH-SY5Y cells subjected to OGD/R.

RESULTS

The results showed that MCAO surgery successfully produced an infarct, and the PNS, NEP1-40, and N+P groups exhibited increased body mass and ameliorated neurological deficits compared with the model group. NEP1-40 treatment markedly reduced NgR1 and RhoA overexpression when compared to the model group, although there was no significant difference in ROCK2 expression. PNS and N+P treatment significantly decreased NgR1, RhoA, and ROCK2 overexpression compared with the model group. However, N+P treatment did not result in a synergistic effect, as assessed by immunohistochemistry, western blotting, and qRT-PCR. Following optimal administration of PNS (160μg/ml) and NEP1-40 (10ng/ml) on SH-SY5Y cells exposed to OGD/R injury, cell viability in the NEP1-40, PNS, and N+P groups significantly increased compared with the model group, as assessed by CCK8 analysis. Additionally, NgR1, RhoA, and ROCK2 mRNA expression profiles were significantly less in the NEP1-40, PNS, and N+P groups compared with the model group.

CONCLUSION

PNS provided neuroprotective effects in a rat model of cerebral ischemia and SH-SY5Y cells exposed to oxygen/glucose deprivation injury by inhibiting the overexpression of NgR1, RhoA, and ROCK2.

Neuroprotective and Cognition-Enhancing Effects of Compound K Isolated from Red Ginseng

The present study was aimed at elucidating the effect of compound K derived from red ginseng on memory function in mouse model and glutamate-induced cytotoxicity in mouse hippocampal HT22 cells. Compound K induced antioxidant enzymes in nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated manner, and effectively attenuated cytotoxicity and mitochondrial damage induced by glutamate in HT22 cells. However, the cytoprotective effect by compound K was abolished by heme oxygenase-1 inhibitor, tin protophorphyrin IX, suggesting that neuroprotective effect of compound K was caused by its Nrf2-mediated induction of antioxidant enzymes. Further, memory deficit induced by scopolamine was restored by compound K, which did not inhibit acetylcholine esterase, in C57BL/6 mice but not in Nrf2 knockout mice as assessed by passive avoidance test, Y-maze and water maze tests, suggesting that scopolamine-induced memory impairment was overcome by the induction of Nrf2-mediated antioxidant enzymes by the compound K. Overall, our data indicate that compound K could be useful in prevention and treatment of reactive oxygen species-induced neurological disorders such as Alzheimer's disease.