Neuroprotective and Neurological/Cognitive Enhancement Effects of Curcumin after Brain Ischemia Injury with Alzheimer's Disease Phenotype

Role of PCBP2 in regulating nanovesicles loaded with curcumin to mitigate neuroferroptosis in neural damage caused by heat stroke

OBJECTIVE

This study aims to elucidate the mechanisms by which nanovesicles (NVs) transport curcumin(CUR) across the blood-brain barrier to treat hypothalamic neural damage induced by heat stroke by regulating the expression of poly(c)-binding protein 2 (PCBP2).

METHODS

Initially, NVs were prepared from macrophages using a continuous extrusion method. Subsequently, CUR was loaded into NVs using sonication, yielding engineered cell membrane Nanovesicles loaded with curcumin (NVs-CUR), which were characterized and subjected to in vitro and in vivo tracking analysis. Evaluations included assessing the toxicity of NVs-CUR using the MTT assay, evaluating neuroprotection of NVs-CUR against H2O2-induced oxidative stress damage in PC12 cells, examining effects on cell morphology and quantity, and detecting ferroptosis-related markers through Western blot and transmission electron microscopy (TEM). Proteomic analysis was conducted on PC12 cells treated with NVs (n = 3) and NVs-CUR (n = 3) to identify downstream key factors. Subsequently, the expression of key factors was modulated, and rescue experiments were performed to validate the impact of NVs-CUR through the regulation of key factor expression. Furthermore, a mouse model of hypothalamic neural damage induced by heat stroke was established, where CUR, NVs-CUR, and ferroptosis inducer Erastin were administered to observe mouse survival rates, conduct nerve function deficit scoring, perform histological staining, and measure levels of inflammation and oxidative stress factors in hypothalamic tissue.

RESULTS

NVs-CUR was successfully prepared with excellent stability, serving as an advantageous drug delivery system that effectively targets brain injury sites or neurons both in vitro and in vivo. Subsequent in vitro cell experiments demonstrated the biocompatibility of NVs-CUR, showing superior protective effects against H2O2-induced PC12 cell damage and reduced ferroptosis compared to CUR. Moreover, in the mouse model of hypothalamic neural damage induced by heat stroke, NVs-CUR exhibited enhanced therapeutic effects. Proteomic analysis revealed that NVs-CUR exerted its effects through the regulation of key protein PCBP2; silencing PCBP2 reversed the protective effect of NVs-CUR on neural damage and its inhibition of ferroptosis. Additionally, NVs-CUR regulated solute carrier family 7 member 11 (SLC7A11) expression by PCBP2; overexpression of SLC7A11 reversed the promotion of neural damage and ferroptosis by silencing PCBP2. Animal experiments indicated that ferroptosis inducers reversed the improved survival and nerve function observed with NVs-CUR, silencing PCBP2 reversed the ameliorative effects of NVs-CUR on hypothalamic neural injury induced by heat stroke, and overexpression of SLC7A11 further reversed the adverse effects of silencing PCBP2 on hypothalamic neural injury induced by heat stroke. This suggests that NVs-CUR alleviates hypothalamic neural damage induced by heat stroke by targeting the PCBP2/SLC7A11 axis to reduce neuronal ferroptosis.

CONCLUSION

This study successfully developed engineered cell membrane NVs-CUR with neuron-targeting properties. NVs-CUR increased the expression of PCBP2, maintained the stability of SLC7A11 mRNA, reduced ferroptosis, and ultimately alleviated hypothalamic neuroinflammation induced by heatstroke.

Potential Protective Effects of Pungent Flavor Components in Neurodegenerative Diseases

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD) have become a major global health burden, but the detailed pathogeneses of neurodegenerative diseases are still unknown, and current treatments are mainly aimed at controlling symptoms; there are no curative treatments for neurodegenerative diseases or treatments for the progressive cognitive, behavioral, and functional impairments that they cause. Studies have shown that some plant extracts with pungent flavor components have a certain neuroprotective effect in neurodegenerative diseases, and their mechanisms mainly involve inhibiting neuronal apoptosis, promoting neuronal regeneration, reducing mitochondrial degeneration, and reducing the production of oxides such as reactive oxygen species in cells, which are of great significance for exploring the treatment of neurodegenerative diseases. In this review, we searched the PubMed database for relevant literature collected in the past 15 years. Finally, we summarized the protective effects of pungent flavor components such as capsaicin, piperine, curcumin, cannabinoids, allicin, and nicotine on the nervous system, focusing on the molecular mechanisms and signaling pathways that they activate. In addition, we also compiled and summarized the laboratory experiments, preclinical experiments, and effects of various pungent flavor components in neurodegenerative diseases. The goal is to further explore their potential as effective drugs for the treatment of neurodegenerative diseases and provide new ideas for further research on the specific protective mechanisms of these substances for the treatment of neurodegenerative diseases and the targets of drug action in the future.

Potential of Natural Products in the Treatment of Glioma: Focus on Molecular Mechanisms

Despite the waning of traditional treatments for glioma due to possible long-term issues, the healing possibilities of substances derived from nature have been reignited in the scientific community. These natural substances, commonly found in fruits and vegetables, are considered potential alternatives to pharmaceuticals, as they have been shown in prior research to impact pathways surrounding cancer progression, metastases, invasion, and resistance. This review will explore the supposed molecular mechanisms of different natural components, such as berberine, curcumin, coffee, resveratrol, epigallocatechin-3-gallate, quercetin, tanshinone, silymarin, coumarin, and lycopene, concerning glioma treatment. While the benefits of a balanced diet containing these compounds are widely recognized, there is considerable scope for investigating the efficacy of these natural products in treating glioma.

Curcumin Administration Routes in Breast Cancer Treatment

Breast cancer is a public health concern worldwide, characterized by increasing incidence and mortality rates, requiring novel and effective therapeutic strategies. Curcumin is a bioactive compound extracted from turmeric with several pharmacological activities. Curcumin is a multifaceted anticancer agent through mechanisms including the modulation of signaling pathways, inhibition of cell proliferation, induction of apoptosis, and production of reactive oxygen species. However, the poor water solubility and bioavailability of curcumin create important barriers in its clinical application. This review elaborates on the therapeutic potential of curcumin in breast cancer treatment, focusing on the efficacy of different administration routes and synergistic effects with other therapeutic agents. The intravenous administration of curcumin-loaded nanoparticles significantly improves bioavailability and therapeutic outcomes compared to oral routes. Innovative formulations, such as nano-emulsifying drug delivery systems, have shown promise in enhancing oral bioavailability. While intravenous delivery ensures higher bioavailability and direct action on tumor cells, it is more invasive and expensive than oral administration. Advancing research on curcumin in breast cancer treatment is essential for improving therapeutic outcomes and enhancing the quality of life of patients.

The role of polyphenols in modulating mitophagy: Implications for therapeutic interventions

This review rigorously assesses the burgeoning research into the role of polyphenols in modulating mitophagy, an essential cellular mechanism for the targeted removal of impaired mitochondria. These natural compounds, known for their low toxicity, are underscored for their potential in therapeutic strategies against a diverse array of diseases, such as neurodegenerative, cardiovascular, and musculoskeletal disorders. The analysis penetrates deeply into the molecular mechanisms whereby polyphenols promote mitophagy, particularly by influencing crucial signaling pathways and transcriptional regulators, including the phosphatase and tensin homolog (PTEN) induced putative kinase 1 (PINK1)/parkin and forkhead box O3 (FOXO3a) pathways. Noteworthy discoveries include the neuroprotective properties of resveratrol and curcumin, which affect both autophagic pathways and mitochondrial dynamics, and the pioneering integration of polyphenols with other natural substances to amplify therapeutic effectiveness. Furthermore, the review confronts the issue of polyphenol bioavailability and emphasizes the imperative for clinical trials to corroborate their therapeutic viability. By delivering an exhaustive synthesis of contemporary insights and recent advancements in polyphenol and mitophagy research, this review endeavors to catalyze additional research and foster the creation of innovative therapeutic modalities that exploit the distinctive attributes of polyphenols to manage and prevent disease.

Curcumin encapsulated in milk small extracellular vesicles as a nanotherapeutic alternative in experimental chronic liver disease

Curcumin is a natural molecule widely tested in preclinical and clinical studies due to its antioxidant and anti-inflammatory activity. Nevertheless, its high hydrophobicity and low bioavailability limit in vivo applications. To overcome curcumin´s drawbacks, small extracellular vesicles (sEVs) have emerged as potential drug delivery systems due to their non-immunogenicity, nanometric size and amphiphilic composition. This work presents curcumin cargo into milk sEV structure and further in vitro and in vivo evaluation as a therapeutic nanoplatform. The encapsulation of curcumin into sEV was performed by two methodologies under physiological conditions: a passive incorporation and active cargo employing saponin. Loaded sEVs (sEVCurPas and sEVCurAc) were fully characterized by physicochemical techniques, confirming that neither methodology affects the morphology or size of the nanoparticles (sEV: 113.3±5.1 nm, sEVCurPas: 127.0±4.5 nm and sEVCurAc: 98.5±3.6 nm). Through the active approach with saponin (sEVCurAc), a three-fold higher cargo was obtained (433.5 µg/mL) in comparison with the passive approach (129.1 µg/mL). These sEVCurAc were further evaluated in vitro by metabolic activity assay (MTT), confocal microscopy, and flow cytometry, showing a higher cytotoxic effect in the tumoral cells RAW264.7 and HepG2 than in primary hepatocytes, specially at high doses of sEVCurAc (4%, 15% and 30% of viability). In vivo evaluation in an experimental model of liver fibrosis confirmed sEVCurAc therapeutic effects, leading to a significant decrease of serum markers of liver damage (ALT) (557 U/L to 338 U/L with sEVCurAc therapy) and a tendency towards decreased liver fibrogenesis and extracellular matrix (ECM) deposition.

Understanding cellular senescence: pathways involved, therapeutics and longevity aiding

A normal somatic cell undergoes cycles of finite cellular divisions. The presence of surveillance checkpoints arrests cell division in response to stress inducers: oxidative stress from excess free radicals, oncogene-induced abnormalities, genotoxic stress, and telomere attrition. When facing such stress when undergoing these damages, there is a brief pause in the cell cycle to enable repair mechanisms. Also, the nature of stress determines whether the cell goes for repair or permanent arrest. As the cells experience transient or permanent stress, they subsequently choose the quiescence or senescence stage, respectively. Quiescence is an essential stage that allows the arrested/damaged cells to go through appropriate repair mechanisms and then revert to the mainstream cell cycle. However, senescent cells are irreversible and accumulate with age, resulting in inflammation and various age-related disorders. In this review, we focus on senescence-associated pathways and therapeutics understanding cellular senescence as a cascade that leads to aging, while discussing the recent details on the molecular pathways involved in regulating senescence and the benefits of therapeutic strategies against accumulated senescent cells and their secretions.

Prolactin-induced neuroprotection against excitotoxicity is mediated via PI3K/AKT and GSK3β/NF-κB in primary cultures of hippocampal neurons

Prolactin (PRL) is a polypeptide hormone that has been reported to play a significant role in neuroprotection against neuronal excitotoxicity produced by glutamate (Glu) or kainic acid (KA) in both, in vitro and in vivo models. However, the molecular mechanisms involved in PRL's neuroprotective effects in the hippocampus have not been completely elucidated. The aim of the present study was to assess the signaling pathways involved in PRL neuroprotection against excitotoxicity. Primary rat hippocampal neuronal cell cultures were used to assess PRL-induced signaling pathway activation. The effects of PRL on neuronal viability, as well as its effects on activation of key regulatory pathways, phosphoinositide 3-kinases/Protein Kinase B (PI3K/AKT) and glycogen synthase kinase 3β / nuclear factor kappa B (GSK3β/NF-κB), were evaluated under conditions of Glutamate-induced excitotoxicity. Additionally, the effect on downstream regulated genes such as Bcl-2 and Nrf2, was assessed. Here, we show that the PI3K/AKT signaling pathway is activated by PRL treatment during excitotoxicity, promoting neuronal survival through upregulation of active AKT and GSK3β/NF-κB, resulting in induction of Bcl-2 and Nrf2 gene expression. Inhibition of the PI3K/AKT signaling pathway abrogated the protective effect of PRL against Glu-induced neuronal death. Overall, results indicate that the neuroprotective actions of PRL are mediated in part, by the activation of the AKT pathway and survival genes. Our data support the idea that PRL could be useful as a potential neuroprotective agent in different neurological and neurodegenerative diseases.

PKCε inhibition prevents ischemia‑induced dendritic spine impairment in cultured primary neurons

Brain ischemia is an independent risk factor for Alzheimer's disease (AD); however, the mechanisms underlining ischemic stroke and AD remain unclear. The present study aimed to investigate the function of the ε isoform of protein kinase C (PKCε) in brain ischemia-induced dendritic spine dysfunction to elucidate how brain ischemia causes AD. In the present study, primary hippocampus and cortical neurons were cultured while an oxygen-glucose deprivation (OGD) model was used to simulate brain ischemia. In the OGD cell model, in vitro kinase activity assay was performed to investigate whether the PKCε kinase activity changed after OGD treatment. Confocal microscopy was performed to investigate whether inhibiting PKCε kinase activity protects dendritic spine morphology and function. G-LISA was used to investigate whether small GTPases worked downstream of PKCε. The results showed that PKCε kinase activity was significantly increased following OGD treatment in primary neurons, leading to dendritic spine dysfunction. Pre-treatment with PKCε-inhibiting peptide, which blocks PKCε activity, significantly rescued dendritic spine function following OGD treatment. Furthermore, PKCε could activate Ras homolog gene family member A (RhoA) as a downstream molecule, which mediated OGD-induced dendritic spine morphology changes and caused dendritic spine dysfunction. In conclusion, the present study demonstrated that the PKCε/RhoA signalling pathway is a novel mechanism mediating brain ischemia-induced dendritic spine dysfunction. Developing therapeutic targets for this pathway may protect against and prevent brain ischemia-induced cognitive impairment and AD.

Functional Nutrition as Integrated Intervention for In- and Outpatient with Schizophrenia

Schizophrenia is a chronic and progressive disorder characterized by cognitive, emotional, and behavioral abnormalities associated with neuronal development and synaptic plasticity alterations. Genetic and epigenetic abnormalities in cortical parvalbumin-positive GABAergic interneurons and consequent alterations in glutamate-mediated excitatory neurotransmission during early neurodevelopment underlie schizophrenia manifestation and progression. Also, epigenetic alterations during pregnancy or early phases of postnatal life are associated with schizophrenia vulnerability and inflammatory processes, which are at the basis of brain pathology and a higher risk of comorbidities, including cardiovascular diseases and metabolic syndrome. In addition, schizophrenia patients adopt an unhealthy lifestyle and poor nutrition, leading to premature death. Here, I explored the role of functional nutrition as an integrated intervention for the long-term management of patients with schizophrenia. Several natural bioactive compounds in plant-based whole foods, including flavonoids, phytonutrients, vitamins, fatty acids, and minerals, modulate brain functioning by targeting neuroinflammation and improving cognitive decline. Although further clinical studies are needed, a functional diet rich in natural bioactive compounds might be effective in synergism with standard treatments to improve schizophrenia symptoms and reduce the risk of comorbidities.

Ischemia as a common trigger for Alzheimer’s disease

Alzheimer’s disease has various potential etiologies, all culminating in the accumulation of beta -amyloid derivatives and significant cognitive decline. Vascular-related pathology is one of the more frequent etiologies, especially in persons older than 65 years, as vascular risk factors are linked to both cerebrovascular disease and the development of AD. The vascular patho-mechanism includes atherosclerosis, large and small vessel arteriosclerosis, cortical and subcortical infarcts, white matter lesions, and microbleeds. These insults cause hypoperfusion, tissue ischemia, chronic inflammation, neuronal death, gliosis, cerebral atrophy, and accumulation of beta-amyloid and phosphorylated tau proteins. In preclinical studies, hyperbaric oxygen therapy has been shown to reverse brain ischemia, and thus alleviate inflammation, reverse the accumulation of beta-amyloid, induce regeneration of axonal white matter, stimulate axonal growth, promote blood–brain barrier integrity, reduce inflammatory reactions, and improve brain performance. In this perspective article we will summarize the patho-mechanisms induced by brain ischemia and their contribution to the development of AD. We will also review the potential role of interventions that aim to reverse brain ischemia, and discuss their relevance for clinical practice.

On the Common Journey of Neural Cells through Ischemic Brain Injury and Alzheimer's Disease

Ischemic brain injury and Alzheimer's disease (AD) both lead to cell death in the central nervous system (CNS) and thus negatively affect particularly the elderly population. Due to the lack of a definitive cure for brain ischemia and AD, it is advisable to carefully study, compare, and contrast the mechanisms that trigger, and are involved in, both neuropathologies. A deeper understanding of these mechanisms may help ameliorate, or even prevent, the destructive effects of neurodegenerative disorders. In this review, we deal with ischemic damage and AD, with the main emphasis on the common properties of these CNS disorders. Importantly, we discuss the Wnt signaling pathway as a significant factor in the cell fate determination and cell survival in the diseased adult CNS. Finally, we summarize the interesting findings that may improve or complement the current sparse and insufficient treatments for brain ischemia and AD, and we delineate prospective directions in regenerative medicine.

Dexmedetomidine exerts a protective effect on ischemic brain injury by inhibiting the P2X7R/NLRP3/Caspase-1 signaling pathway

Dexmedetomidine (Dex) has been suggested to exert a protective function in ischemic brain injury. In this study, we aimed to elucidate the intrinsic mechanisms of Dex in regulating microglia pyroptosis in ischemic brain injury via the purinergic 2X7 receptor (P2X7R)/NLRP3/Caspase-1 signaling pathway. First, permanent middle cerebral artery occlusion (p-MCAO) rat model was established, followed by the measurement of behavioral deficit, neuronal injury, the volume of brain edema and the infarct size. Dex treatment was suggested to alleviate the neurological deficits in p-MCAO rats and reduce the brain water content and infarct size. Additionally, rat microglia were cultured in vitro and a model of oxygen and glucose (OGD) was established. Microglia cell activity and ultrastructure were detected. Dex could increase cell activity and reduce LDH activity, partially reversing the changes in cell morphology. Furthermore, the activation of P2X7R/NLRP3/Caspase-1 pathway was tested. The obtained findings indicated Dex suppressed microglial pyroptosis by inhibiting the P2X7R/NLRP3/Caspase-1 pathway. Inhibition of P2X7R or NLRP3 could inhibit Caspase-1 p10 expression, improve cell activity, and reduce LDH activity. The same result was verified in vivo experiments. This study indicated that Dex inhibited microglia pyroptosis by blocking the P2X7R/NLRP3/Caspase-1 pathway, thus playing a protective role against ischemic brain injury.

Administration of 4-Hydroxy-3,5-Di-Tertbutyl Cinnamic Acid Restores Mitochondrial Function in Rabbits with Cerebral Ischemia

The aim of the study is to evaluate the effect of 4-hydroxy-3,5- di-tertbutyl cinnamic acid on the change in mitochondrial function under conditions of experimental cerebral ischemia in rabbits. The study was performed on 48 male rabbits, which were used for modeling permanent cerebral ischemia by occlusion of the common carotid arteries. The test compound was administered before modeling ischemia for 14 days and after the occurrence of reproducing ischemia, in a similar time interval. After that, neurological deficit and the parameters of mitochondrial respiration, the intensity of anaerobic processes, the latent opening time of the mitochondrial permeability transition pore, the value of the mitochondrial membrane potential and the concentration of caspase – 3 were determined. The administration of 100 mg/kg of 4-hydroxy-3,5-di-tertbutyl cinnamic acid into the animals reduced neurological deficit and restored the mitochondrial membrane potential. Prophylactic administration of 4-hydroxy- 3,5-di-tertbutyl cinnamic acid, contributed to an increase in ATPgenerating ability, the maximum level of respiration and respiratory capacity by 4.1 times (p<0.01), 4.8 times (p<0.01) and 4.3 times (p<0.01), respectively. With therapeutic administration, these indicators increased by 11 times (p<0.01), 12.2 times (p<0.01) and 8.6 times (p<0.01), respectively. Also, both the prophylactic and therapeutic use of 4-hydroxy-3,5-di-tret-butyl cinnamic acid normalized aerobic/anaerobic metabolism, as well as reduced the concentration of caspase-3. Based on the obtained data, significant cerebroprotective properties of 4-hydroxy-3,5- di-tertbutyl cinnamic acid can be assumed. Moreover, the potential mechanism of action of this compound may be mediated by the normalization of mitochondrial function.

RETRACTED: MicroRNA-376b-5p targets SOX7 to alleviate ischemic brain injury in a mouse model through activating Wnt/β-catenin signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Fig. 1B+C, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0). The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Decoding signaling pathways involved in prolactin-induced neuroprotection: A review

It has been well recognized that prolactin (PRL), a pleiotropic hormone, has many functions in the brain, such as maternal behavior, neurogenesis, and neuronal plasticity, among others. Recently, it has been reported to have a significant role in neuroprotection against excitotoxicity. Glutamate excitotoxicity is a common alteration in many neurological and neurodegenerative diseases, leading to neuronal death. In this sense, several efforts have been made to decrease the progression of these pathologies. Despite various reports of PRL's neuroprotective effect against excitotoxicity, the signaling pathways that underlie this mechanism remain unclear. This review aims to describe the most recent and relevant studies on the molecular signaling pathways, particularly, PI3K/AKT, NF-κB, and JAK2/STAT5, which are currently under investigation and might be implicated in the molecular mechanisms that explain the PRL effects against excitotoxicity and neuroprotection. Remarkable neuroprotective effects of PRL might be useful in the treatment of some neurological diseases.

Molecular effects of curcumin on the experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis (MS). Previous studies have shown that myelin degradation during MS and EAE resulted in reduced expression of some of the proteins, e.g., the MBP (myelin basic protein), and increased expression of genes such as iNOS (Inducible nitric oxide synthase) and NOGO-A in the affected patients. In the present study, EAE was induced by immunizing Wistar rats (n=12) with homogenized spinal cord of guinea pig and Freund's complete adjuvant. Curcumin is an active ingredient in turmeric with anti-inflammatory properties, which has been studied in this article. In this study, the effect of curcumin administration on the change of the expression of MBP, NOGO-A, and iNOS genes was evaluated using the RT-PCR (Reverse transcription-polymerase chain reaction) technique. The obtained results indicated it could be concluded that curcumin was able to improve EAE by increasing the amount of MBP gene expression and reducing the intensity of NOGO-A expression.

HSP60 participates in the anti-glioma effects of curcumin

The chaperone protein heat shock protein 60 (HSP60) is considered a tumor promoter in several types of primary human tumors, where it orchestrates a broad range of survival programs. Curcumin (CCM) is well-established to exhibit several anticancer properties with an excellent safety profile. Our previous study showed that CCM suppresses extracellular HSP60 expression, which is typically released by activated microglia, and acts as an inflammatory factor by binding to Toll-like receptor 4 (TLR-4) on the cell membrane. The present study assessed whether CCM exerted its anti-neuroglioma effects on U87 cells via inhibition of HSP60/TLR-4 signaling, similar to that in microglia. The results demonstrated that CCM significantly inhibited the viability and invasive capacity of neuroglioma U87 cells as evidenced by a Cell Counting Kit-8 assay. Western blotting and ELISA results showed that CCM decreased the expression of HSP60 and its transcriptional factor, heat shock factor 1, and reduced HSP60 release. Accordingly, TLR-4, as the target of HSP60, and its downstream signaling proteins myeloid differentiation primary response 88 (MYD88), NF-κB, inducible nitric oxide synthase and cytokines IL-1β and IL-6 were downregulated by CCM. The expression levels of apoptotic factors associated with NF-κB activation, including TNF-α and caspase-3 were increased in U87 cells by CCM treatment, while p53 expression, a tumor suppressor, was shown to be decreased. Based on the results of the present study, CCM may exert its anti-tumor effects in U87 cells by inhibiting the HSP60/TLR-4/MYD88/NF-κB pathway and inducing tumor cell apoptosis. Thus, CCM may be used as a potential therapy for the clinical treatment of neuroglioma.

N-Methyl-D-Aspartate Receptor Signaling-Protein Kinases Crosstalk in Cerebral Ischemia

Although stroke is very often the cause of death worldwide, the burden of ischemic and hemorrhagic stroke varies between regions and over time regarding differences in prognosis, prevalence of risk factors, and treatment strategies. Excitotoxicity, oxidative stress, dysfunction of the blood-brain barrier, neuroinflammation, and lysosomal membrane permeabilization, sequentially lead to the progressive death of neurons. In this process, protein kinases-related checkpoints tightly regulate N-methyl-D-aspartate (NMDA) receptor signaling pathways. One of the major hallmarks of cerebral ischemia is excitotoxicity, characterized by overactivation of glutamate receptors leading to intracellular Ca²⁺ overload and ultimately neuronal death. Thus, reduced expression of postsynaptic density-95 protein and increased protein S-nitrosylation in neurons is responsible for neuronal vulnerability in cerebral ischemia. In this chapter death-associated protein kinases, cyclin-dependent kinase 5, endoplasmic reticulum stress-induced protein kinases, hyperhomocysteinemia-related NMDA receptor overactivation, ephrin-B-dependent amplification of NMDA-evoked neuronal excitotoxicity and lysosomocentric hypothesis have been discussed.Consequently, ample evidences have demonstrated that enhancing extrasynaptic NMDA receptor activity triggers cell death after stroke. In this context, considering the dual roles of NMDA receptors in both promoting neuronal survival and mediating neuronal damage, selective augmentation of NR2A-containing NMDA receptor activation in the presence of NR2B antagonist may constitute a promising therapy for stroke.

Curcumin Prevents Neuroinflammation by Inducing Microglia to Transform into the M2-phenotype via CaMKKβ-dependent Activation of the AMP-Activated Protein Kinase Signal Pathway

BACKGROUND

Neuroinflammation plays an important role in the pathophysiological process of various neurodegenerative diseases. It is well known that curcumin has obvious anti-inflammatory effects in various neuroinflammation models. However, its effect on the modulation of microglial polarization is largely unknown.

OBJECTIVE

This study aimed to investigate whether curcumin changed microglia to an anti-inflammatory M2-phenotype by activating the AMP-activated protein kinase (AMPK) signaling pathway.

METHODS

LPS treatment was used to establish BV2 cells and primary microglia neuroinflammation models. The neuroinflammation mouse model was established by an intracerebroventricular (ICV) injection of lipopolysaccharide (LPS) in the lateral septal complex region of the brain. TNF-α was measured by ELISA, and cell viability was measured by Cell Counting Kit-8 (CCK-8). The expression of proinflammatory and anti-inflammatory cytokines was examined by Q-PCR and Western blot analysis. Phenotypic polarization of BV2 microglia was detected by immunofluorescence.

RESULTS

Curcumin enhanced AMPK activation in BV2 microglial cells in the presence and absence of LPS. Upon LPS stimulation, the addition of curcumin promoted M2 polarization of BV2 cells, as evidenced by suppressed M1 and the elevated M2 signature protein and gene expression. The effects of curcumin were inhibited by an AMPK inhibitor or AMPK knockdown. Calmodulin-dependent protein kinase kinase β (CaMKKβ) and liver kinase B1 (LKB1) are upstream kinases that activate AMPK. Curcumin can activate AMPK in Hela cells, which do not express LKB1. However, both the CaMKKβ inhibitor and siRNA blocked curcumin activation of AMPK in LPS-stimulated BV2 cells. Moreover, the CaMKKβ inhibitor and siRNA weaken the effect of curcumin suppression on M1 and enhancement of M2 protein and gene expression in LPS-stimulated BV2 cells. Finally, curcumin enhanced AMPK activation in the brain area where microglia were over-activated upon LPS stimulation in an in vivo neuroinflammation model. Moreover, curcumin also suppressed M1 and promoted M2 signature protein and gene expression in this in vivo model.

CONCLUSION

Curcumin enhances microglia M2 polarization via the CaMKKβ-dependent AMPK signaling pathway. Additionally, curcumin treatment was found to be neuroprotective and thus might be considered as a novel therapeutic agent to treat the neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, etc.

Neuroprotective effect of emodin against Alzheimer's disease via Nrf2 signaling in U251 cells and APP/PS1 mice

Emodin is a naturally-occurring medicinal herbal ingredient that possesses numerous pharmacological properties, including anti-inflammatory and antioxidant effects. In the present study, potential neuroprotective effects associated with the antioxidant activity of emodin were assessed in U251 cells that were subjected to β-amyloid peptide (Aβ)-induced apoptosis and in amyloid precursor protein (APP)/presenilin-1 (PS1) double-transgenic mice. U251 is a type of human astroglioma cell line (cat. no. BNCC337874; BeNa Culture Collection). In apoptotic U251 cells, 3-h emodin pre-treatment prior to 24-h Aβ co-exposure improved cell viability, suppressed lactate dehydrogenase leakage and caspase-3, −8 and −9 activation to inhibit apoptosis. Compared with those after Aβ exposure alone, emodin ameliorated the dissipation of the mitochondrial membrane potential, inhibited the over-accumulation of reactive oxygen species, enhanced the expression levels of nuclear factor-erythroid-2-related factor 2 (Nrf2), haemeoxygenase-1, superoxide dismutase 1, Bcl-2 and catalase in addition to decreasing the expression levels of Bax. In APP/PS1 mice, an 8-week course of emodin administration improved spatial memory and learning ability and decreased anxiety. Emodin was also found to regulate key components in the Nrf2 pathway and decreased the deposition of Aβ, phosphorylated-τ and 4-hydroxy-2-nonenal in APP/PS1 mice. Taken together, the present data suggest that emodin may serve as a promising candidate for the treatment of Alzheimer's disease.

Advancements in therapeutic drugs targeting of senescence

Aging leads to a high burden on society, both medically and economically. Cellular senescence plays an essential role in the initiation of aging and age-related diseases. Recent studies have highlighted the therapeutic value of senescent cell deletion in natural aging and many age-related disorders. However, the therapeutic strategies for manipulating cellular senescence are still at an early stage of development. Among these strategies, therapeutic drugs that target cellular senescence are arguably the most highly anticipated. Many recent studies have demonstrated that a variety of drugs exhibit healthy aging effects. In this review, we summarize different types of drugs promoting healthy aging – such as senolytics, senescence-associated secretory phenotype (SASP) inhibitors, and nutrient signaling regulators – and provide an update on their potential therapeutic merits. Taken together, our review synthesizes recent advancements in the therapeutic potentialities of drugs promoting healthy aging with regard to their clinical implications.

Prenatal, but not Postnatal, Curcumin Administration Rescues Neuromorphological and Cognitive Alterations in Ts65Dn Down Syndrome Mice

BACKGROUND

The cognitive dysfunction in Down syndrome (DS) is partially caused by deficient neurogenesis during fetal stages. Curcumin enhances neurogenesis and learning and memory.

OBJECTIVES

We aimed to test the ability of curcumin to rescue the neuromorphological and cognitive alterations of the Ts65Dn (TS) mouse model of DS when administered prenatally or during early postnatal stages, and to evaluate whether these effects were maintained several weeks after the treatment.

METHODS

To evaluate the effects of prenatal curcumin administration, 65 pregnant TS females were subcutaneously treated with curcumin (300 mg/kg) or vehicle from ED (Embryonic Day) 10 to PD (Postnatal Day) 2. All the analyses were performed on their TS and Control (CO) male and female progeny. At PD2, the changes in neurogenesis, cellularity, and brain weight were analyzed in 30 TS and CO pups. The long-term effects of prenatal curcumin were evaluated in another cohort of 44 TS and CO mice between PD30 and PD45. The neuromorphological effects of the early postnatal administration of curcumin were assessed on PD15 in 30 male and female TS and CO pups treated with curcumin (300 mg/kg) or vehicle from PD2 to PD15. The long-term neuromorphological and cognitive effects were assessed from PD60 to PD90 in 45 mice. Data was compared by ANOVAs.

RESULTS

Prenatal administration of curcumin increased the brain weight (+45%, P < 0.001), the density of BrdU (bromodeoxyuridine)- (+150%, P < 0.001) and DAPI (4',6-diamidino-2-phenylindole)- (+38%, P = 0.005) positive cells, and produced a long-term improvement of cognition in TS (+35%, P = 0.007) mice with respect to vehicle-treated mice. Postnatal administration of curcumin did not rescue any of the short- or long-term altered phenotypes of TS mice.

CONCLUSION

The beneficial effects of prenatal curcumin administration to TS mice suggest that it could be a therapeutic strategy to treat DS cognitive disabilities.

Curcumin and neurological diseases

Objectives: The beneficial effects of many substances have been discovered because of regular dietary consumption. This is also the case with curcumin, whose effects have been known for more than 4,000 years in Eastern countries such as China and India. A curcumin-rich diet has been known to counteract many human diseases, including cancer and diabetes, and has been shown to reduce inflammation. The effect of a curcumin treatment for neurological diseases, such as spinal muscular atrophy; Alzheimer's disease; Parkinson's disease; amyotrophic lateral sclerosis; multiple sclerosis; and others, has only recently been brought to the attention of researchers and the wider population.Methods: In this paper, we summarise the studies on this natural product, from its isolation two centuries ago to its characterisation a century later.Results: We describe its role in the treatment of neurological diseases, including its cellular and common molecular mechanisms, and we report on the clinical trials of curcumin with healthy people and patients.Discussion: Commenting on the different approaches adopted by the efforts made to increase its bioavailability.

Nose to brain drug delivery - A promising strategy for active components from herbal medicine for treating cerebral ischemia reperfusion

Cerebral ischemia reperfusion injury (CIRI), one of the major causes of death from stroke in the world, not only causes tremendous damage to human health, but also brings heavy economic burden to society. Current available treatments for CIRI, including mechanical therapies and drug therapies, are often accompanied by significant side-effects. Therefore, it is necessary to discovery new strategies for treating CIRI. Many studies have confirmed that the herbal medicine has the advantages of abundant resources, good curative effect and little side effects, which can be used as potential drug for treatment of CIRI through multiple targets. It's known that oral administration commonly has low bioavailability, and injection administration is inconvenient and unsafe. Many drugs can't delivery to brain through routine pathways due to the blood-brain-barrier (BBB). Interestingly, increasing evidences have suggested the nasal administration is a potential direct route to transport drug into brain avoiding the BBB and has the characteristics of high bioavailability for treating brain diseases. Therefore, intranasal administration can be treated as an alternative way to treat brain diseases. In the present review, effective methods to treat CIRI by using active ingredients derived from herbal medicine through nose to brain drug delivery (NBDD) are updated and discussed, and some related pharmacological mechanisms have also been emphasized. Our present study would be beneficial for the further drug development of natural agents from herbal medicines via NBDD.

Anti-allodynic effect induced by curcumin in neuropathic rat is mediated through the NO-cyclic-GMP-ATP sensitive K+ channels pathway

BACKGROUND

Recent studies pointed up that curcumin produces an anti-nociceptive effect in inflammatory and neuropathic pain. However, the possible mechanisms of action that underline the anti-allodynic effect induced by curcumin are not yet established. The purpose of this study was to determine the possible anti-allodynic effect of curcumin in rats with L5-L6 spinal nerve ligation (SNL). Furthermore, we study the possible participation of the NO-cyclic GMP-ATP-sensitive K+ channels pathway in the anti-allodynic effect induced by curcumin.

METHODS

Tactile allodynia was measured using von Frey filaments by the up-down method in female Wistar rats subjected to SNL model of neuropathic pain.

RESULTS

Intrathecal and oral administration of curcumin prevented, in a dose-dependent fashion, SNL-induced tactile allodynia. The anti-allodynic effect induced by curcumin was prevented by the intrathecal administration of L-NAME (100 μg/rat, a non-selective nitric oxide synthase inhibitor), ODQ (10 μg/rat, an inhibitor of guanylate-cyclase), and glibenclamide (50 μg/rat, channel blocker of ATP-sensitive K+ channels).

CONCLUSIONS

These data suggest that the anti-allodynic effect induced by curcumin is mediated, at least in part, by the NO-cyclic GMP-ATP-sensitive K+ channels pathway in the SNL model of neuropathic pain in rats.

Neuroprotection with Natural Antioxidants and Nutraceuticals in the Context of Brain Cell Degeneration: The Epigenetic Connection

Bioactive antioxidant agents present in selected plants are known to provide the first line of biological defense against oxidative stress. In particular, soluble vitamin C, E, carotenoids and phenolic compounds have demonstrated crucial biological effects in cells against oxidative damage, preventing prevalent chronic diseases, such as diabetes, cancer and cardiovascular disease. The reported wide range of effects that included anti-aging, anti-atherosclerosis, anti-inflammatory and anticancer activity were studied against degenerative pathologies of the brain. Vitamins and different phytochemicals are important epigenetic modifiers that prevent neurodegeneration. In order to explore the potential antioxidant sources in functional foods and nutraceuticals against neurodegeneration, the present paper aims to show a comprehensive assessment of antioxidant activity at chemical and cellular levels. The effects of the different bioactive compounds available and their antioxidant activity through an epigenetic point of view are also discussed.

Mutual Two-Way Interactions of Curcumin and Gut Microbiota

Curcumin, an herbal naturally occurring polyphenol, has recently been proposed for the treatment of neurodegenerative, neurological and cancer diseases due to its pleiotropic effect. Recent studies indicated that dysbiosis is associated with the abovementioned and other diseases, and gut microflora may be a new potential therapeutic target. The new working hypothesis that could explain the curative role of curcumin, despite its limited availability, is that curcumin acts indirectly on the brain, affecting the “gut–brain–microflora axis”, a complex two-way system in which the gut microbiome and its composition, are factors that preserve and determine brain health. It is therefore suspected that curcumin and its metabolites have a direct regulatory effect on gut microflora and vice versa, which may explain the paradox between curcumin’s poor bioavailability and its commonly reported therapeutic effects. Curcumin and its metabolites can have health benefits by eliminating intestinal microflora dysbiosis. In addition, curcumin undergoes enzymatic modifications by bacteria, forming pharmacologically more active metabolites than their parent, curcumin. In this review, we summarize a number of studies that highlight the interaction between curcumin and gut microbiota and vice versa, and we consider the possibility of microbiome-targeted therapies using curcumin, particularly in disease entities currently without causal treatment.

AR ubiquitination induced by the curcumin analog suppresses growth of temozolomide-resistant glioblastoma through disrupting GPX4-Mediated redox homeostasis

Drug resistance is the main obstacle in the improvement of chemotherapeutic efficacy in glioblastoma. Previously, we showed that dehydroepiandrosterone (DHEA), one kind of androgen/neurosteroid, potentiates glioblastoma to acquire resistance through attenuating DNA damage. Androgen receptor (AR) activated by DHEA or other types of androgen was reported to promote drug resistance in prostate cancer. However, in DHEA-enriched microenvironment, the role of AR in acquiring resistance of glioblastoma remains unknown. In this study, we found that AR expression is significantly correlated with poor prognosis, and AR obviously induced the resistance to temozolomide (TMZ) treatment. Herein, we observed that ALZ003, a curcumin analog, induces FBXL2-mediated AR ubiquitination, leading to degradation. Importantly, ALZ003 significantly inhibited the survival of TMZ-sensitive and -resistant glioblastoma in vitro and in vivo. The accumulation of reactive oxygen species (ROS), lipid peroxidation and suppression of glutathione peroxidase (GPX) 4, which are characteristics of ferroptosis, were observed in glioblastoma cell after treatment of ALZ003. Furthermore, overexpression of AR prevented ferroptosis in the presence of GPX4. To evaluate the therapeutic effect in vivo, we transplanted TMZ-sensitive or -resistant U87MG cells into mouse brain followed by intravenous administration with ALZ003. In addition to inhibiting the growth of glioblastoma, ALZ003 significantly extended the survival period of transplanted mice, and significantly decreased AR expression in the tumor area. Taken together, AR potentiates TMZ resistance for glioblastoma, and ALZ003-mediated AR ubiquitination might open a new insight into therapeutic strategy for TMZ resistant glioblastoma.

Curcumin Mitigates Neuro-Inflammation by Modulating Microglia Polarization Through Inhibiting TLR4 Axis Signaling Pathway Following Experimental Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) elicits destruction of neuronal cells and neurological function, which is exacerbated by neuro-inflammation in EBI, and toll-like receptor 4 (TLR4) plays an important role in inflammatory cascade via modulation microglia polarization. Curcumin (Cur), as a natural phytochemical compound, has the potential characteristics on anti-inflammatory and microglia phenotype transformation. In this study, we verified the hypothesis curcumin promotes M2 polarization to inhibiting neuro-inflammation, which through suppressing TLR4 signaling pathway after SAH. In tlr4^–/– mice and wild type (WT) subjected to prechiasmatic cistern blood injection, Western blotting, brain water content, neurological score, enzyme-linked immunosorbent assay (ELISA) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were performed to investigate the role of TLR4 on neuro-inflammation response and microglia polarization. Curcumin with three different concentrations (50 mg/kg, 100 mg/kg and 200 mg/kg) were injected intraperitoneally (i.p.) at 15 min after SAH. The levels of TLR4, myeloid differentiation factor 88 (MyD88), nuclear factor- κB (NF-κB), Iba-1, CD86, CD206 and pro/anti-inflammation cytokines were measured by Western blotting and immunofluorescence staining at 24 h after SAH. SAH induction increased the protein levels of TLR4, pro-inflammation cytokines and proportion of M1 phenotype. Curcumin with 100 mg/kg treatment dramatically inhibited the release of pro-inflammatory mediators, and elevated the protein levels of anti-inflammatory cytokines and promoted microglia switch to M2. Meanwhile, curcumin treatment also decreased the expressions of TLR4, Myd88 and NF-κB at 24 h post SAH. TLR4 deficiency ameliorated brain water content, neurological deficit and reduced pro-inflammation cytokines after SAH. Moreover, curcumin treatment in tlr4^–/– mice further induced M2 polarization, while had no statistic difference on brain water content and neurological score at 24 h post SAH. Our results indicated that curcumin treatment alleviated neuro-inflammation response through promoting microglia phenotype shift toward M2, and which might inhibiting TLR4/MyD88/NF-κB signaling pathway after SAH.

Dietary Supplementation of the Antioxidant Curcumin Halts Systemic LPS-Induced Neuroinflammation-Associated Neurodegeneration and Memory/Synaptic Impairment via the JNK/NF-κB/Akt Signaling Pathway in Adult Rats

Curcumin is a natural polyphenolic compound widely known to have antioxidant, anti-inflammatory, and antiapoptotic properties. In the present study, we explored the neuroprotective effect of curcumin against lipopolysaccharide- (LPS-) induced reactive oxygen species- (ROS-) mediated neuroinflammation, neurodegeneration, and memory deficits in the adult rat hippocampus via regulation of the JNK/NF-κB/Akt signaling pathway. Adult rats were treated intraperitoneally with LPS at a dose of 250 μg/kg for 7 days and curcumin at a dose of 300 mg/kg for 14 days. After 14 days, the rats were sacrificed, and western blotting and ROS and lipid peroxidation assays were performed. For immunohistochemistry and confocal microscopy, the rats were perfused transcardially with 4% paraformaldehyde. In order to verify the JNK-dependent neuroprotective effect of curcumin and to confirm the in vivo results, HT-22 neuronal and BV2 microglial cells were exposed to LPS at a dose of 1 μg/ml, curcumin 100 μg/ml, and SP600125 (a specific JNK inhibitor) 20 μM. Our immunohistochemical, immunofluorescence, and biochemical results revealed that curcumin inhibited LPS-induced oxidative stress by reducing malondialdehyde and 2,7-dichlorofluorescein levels and ameliorating neuroinflammation and neuronal cell death via regulation of the JNK/NF-κB/Akt signaling pathway both in vivo (adult rat hippocampus) and in vitro (HT-22/BV2 cell lines). Moreover, curcumin markedly improved LPS-induced memory impairment in the Morris water maze and Y-maze tasks. Taken together, our results suggest that curcumin may be a potential preventive and therapeutic candidate for LPS-induced ROS-mediated neurotoxicity and memory deficits in an adult rat model.

The Autophagy Signaling Pathway: A Potential Multifunctional Therapeutic Target of Curcumin in Neurological and Neuromuscular Diseases

Autophagy is the major intracellular machinery for degrading proteins, lipids, polysaccharides, and organelles. This cellular process is essential for the maintenance of the correct cellular balance in both physiological and stress conditions. Because of its role in maintaining cellular homeostasis, dysregulation of autophagy leads to various disease manifestations, such as inflammation, metabolic alterations, aging, and neurodegeneration. A common feature of many neurologic and neuromuscular diseases is the alteration of the autophagy-lysosomal pathways. For this reason, autophagy is considered a target for the prevention and/or cure of these diseases. Dietary intake of polyphenols has been demonstrated to prevent/ameliorate several of these diseases. Thus, natural products that can modulate the autophagy machinery are considered a promising therapeutic strategy. In particular, curcumin, a phenolic compound widely used as a dietary supplement, exerts an important effect in modulating autophagy. Herein, we report on the current knowledge concerning the role of curcumin in modulating the autophagy machinery in various neurological and neuromuscular diseases as well as its role in restoring the autophagy molecular mechanism in several cell types that have different effects on the progression of neurological and neuromuscular disorders.

Diet and Alzheimer's dementia - Nutritional approach to modulate inflammation

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disease causing dementia in the elderly population. Due to the fact that there is still no cure for Alzheimer's dementia and available treatment strategies bring only symptomatic benefits, there is a pressing demand for other effective strategies such as diet. Since the inflammation hypothesis gained considerable significance in the AD pathogenesis, elucidating the modulatory role of dietary factors on inflammation may help to prevent, delay the onset and slow the progression of AD. Current evidence clearly shows that synergistic action of combined supplementation and complex dietary patterns provides stronger benefits than any single component considered separately. Recent studies reveal the growing importance of novel factors such as dietary advanced glycation end products (d-AGE), gut microbiota, butyrate and vitamin D₃ on inflammatory processes in AD.

CONCLUSION

This paper summarizes the available evidence of pro- and anti-inflammatory activity of some dietary components including fatty acids, vitamins, flavonoids, polyphenols, probiotics and d-AGE, and their potential for AD prevention and treatment.