Chitosan prevents oxidative stress-induced amyloid β formation and cytotoxicity in NT2 neurons: involvement of transcription factors Nrf2 and NF-κB

Physicochemical Property Effects on Immune Modulating Polymeric Nanoparticles: Potential Applications in Spinal Cord Injury

Nanoparticles (NPs) offer promising potential as therapeutic agents for inflammation-related diseases, owing to their capabilities in drug delivery and immune modulation. In preclinical studies focusing on spinal cord injury (SCI), polymeric NPs have demonstrated the ability to reprogram innate immune cells. This reprogramming results in redirecting immune cells away from the injury site, downregulating pro-inflammatory signaling, and promoting a regenerative environment post-injury. However, to fully understand the mechanisms driving these effects and maximize therapeutic efficacy, it is crucial to assess NP interactions with innate immune cells. This review examines how the physicochemical properties of polymeric NPs influence their modulation of the immune system. To achieve this, the review delves into the roles played by innate immune cells in SCI and investigates how various NP properties influence cellular interactions and subsequent immune modulation. Key NP properties such as size, surface charge, molecular weight, shape/morphology, surface functionalization, and polymer composition are thoroughly examined. Furthermore, the review establishes connections between these properties and their effects on the immunomodulatory functions of NPs. Ultimately, this review suggests that leveraging NPs and their physicochemical properties could serve as a promising therapeutic strategy for treating SCI and potentially other inflammatory diseases.

Chitosan-Based Nanoformulations: Preclinical Investigations, Theranostic Advancements, and Clinical Trial Prospects for Targeting Diverse Pathologies

Chitosan, a biocompatible and biodegradable polymer, has attracted significant interest in the development of nanoformulations for targeted drug delivery and therapeutic applications. The versatility of chitosan lies in its modifiable functional groups, which can be tailored to diverse applications. Nanoparticles derived from chitosan and its derivatives typically exhibit a positive surface charge and mucoadhesive properties, enabling them to adhere to negatively charged biological membranes and gradually release therapeutic agents. This comprehensive review investigates the manifold roles of chitosan-based nanocarriers, ranging from preclinical research to theranostic applications and clinical trials, across a spectrum of diseases, including neurological disorders, cardiovascular diseases, cancer, wound healing, gastrointestinal disorders, and pulmonary diseases. The exploration starts with an overview of preclinical studies, emphasizing the potential of chitosan-based nanoformulations in optimizing drug delivery, improving therapeutic outcomes, and mitigating adverse effects in various disease categories. Advancements in theranostic applications of chitosan-based nanoformulations highlight their adaptability to diverse diseases. As these nanoformulations progress toward clinical translation, this review also addresses the regulatory challenges associated with their development and proposes potential solutions.

A review of chitosan polysaccharides: Neuropharmacological implications and tissue regeneration

One of the current challenges in targeting neurological disorders is that many therapeutic molecules cannot cross the blood-brain barrier (BBB), which limits the use of natural molecules in nervous tissue regeneration. Thus, the development of new drugs to effectively treat neurological disorders would be a challenge. Natural resources are well known as a source of several therapeutic agents for the treatment of neurologic disorders. Recently, chitosan (CTS) and its derivatives from arthropod exoskeletons, have attracted much attention as a drug delivery system to transport therapeutic substances across the BBB and thanks to other neuroprotective effects including the participation to the CNS regenerations scaffolds to replicate the extracellular matrix and microenvironment of the body. This review will discuss the place of natural resource therapy in targeting neurological disorders. In particular, it will highlight recent understanding and progress in the applications of CTS as drug delivery systems and their therapeutic effects on these disorders through tissue regeneration, as well as the molecular mechanisms by which they exert these effects.

The Protective Role of Heat Shock Proteins against Stresses in Animal Breeding

Heat shock proteins (HSPs) play an important role in all living organisms under stress conditions by acting as molecular chaperones. The expression of different HSPs during stress varies depending on their protective functions and anti-apoptotic activities. The application of HSPs improves the efficiency and decreases the economic cost of animal breeding. By upregulating the expression of HSPs, feed supplements can improve stress tolerance in farm animals. In addition, high expression of HSPs is often a feature of tumor cells, and inhibiting the expression of HSPs is a promising novel method for killing these cells and treating cancers. In the present review, the findings of previous research on the application of HSPs in animal breeding and veterinary medicine are summarized, and the knowledge of the actions of HSPs in animals is briefly discussed.

Fe3O4@Chitosan@ZIF-8@RVG29, an anti-glioma nanoplatform guided by fixed and activated by alternating magnetic field

There is considerable interest in developing anti-glioma nanoplatforms. They make the all-in-one combination of therapies possible. Here we show how the selective Glioblastoma multiforme (GBM) cell killing of the here-established nanoplatforms increased after each coating and how the here-established vibration-inducing Alternating magnetic field (AMF) decreased the treatment time from 72 h to 30 s. Thanks to their magnetite core, these nanoplatforms can be guided to the tumor's specific site by a Fixed magnetic field, they bypass the Blood-Brain Barrier (BBB) and accumulate at the tumor site thanks to the RVG29 bonding to the G-protein on the ion-gated channel receptor known as the nicotinic acetylcholine receptor (nAchR), which expresses on BBB cells and overexpresses on GBM cells, and thanks to the positive charge gained by both chitosan and RVG29's peptide. Both ZIF-8 and its mediate adherence, Chitosan increases the drug loading capacity that stimuli response to the tumor's acidic environment. The Zn2+ ions generated from ZIF-8 sustained degradation in such an environment kill the GBM cells. Dynamic Light Scattering (DLS) evaluated these nanoplatform's mean size 155 nm indicating their almost optimum size for brain applications. Based on their elements' intrinsic properties, these nanoplatforms can enhance and combine other adjuvant therapies.

Polysaccharides: potential bioactive macromolecules for Alzheimer's disease

Alzheimer's disease (AD) is one of the leading causes of death and disability. AD is a devastating disease that has caused an overwhelming burden. However, no disease-modified treatment was discovered. The approval of sodium oligomannate (GV-971) in mild-moderate AD patients has attracted great attention to investigate the role of saccharides in AD. Therefore, summarizing and explaining the role of saccharides in AD is urgent and promising. Recent studies showed that polysaccharides (PSs) potentially benefit AD in vitro and in vivo. PSs could alleviate the pathological damage and improve cognitive symptoms via (1) antagonizing the toxicity of abnormal amyloid-beta and tau proteins; (2) attenuating oxidative stress and proinflammation; (3) rebuilding neuroplasticity. PSs exhibit one-multiple pathological hits of AD. However, a thorough chemical investigation is needed for further study.

Association between insulin and Nrf2 signalling pathway in Alzheimer's disease: A molecular landscape

Insulin, a well-known hormone, has been implicated as a regulator of blood glucose levels for almost a century now. Over the past few decades, the non-glycemic actions of insulin i.e. neuronal growth and proliferation have been extensively studied. In 2005, Dr. Suzanne de La Monte and her team reported that insulin might be involved in the pathogenesis of Alzheimer's Disease (AD) and thus coined a term "Type-3 diabetes" This hypothesis was supported by several subsequent studies. The nuclear factor erythroid 2- related factor 2 (Nrf2) triggers a cascade of events under the regulation of distinct mechanisms including protein stability, phosphorylation and nuclear cytoplasmic shuttling, finally leading to the protection against oxidative damage. The Nrf2 pathway has been investigated extensively in relevance to neurodegenerative disorders, particularly AD. Many studies have indicated a strong correlation between insulin and Nrf2 signalling pathways both in the periphery and the brainbut merely few of them have focused on elucidating their inter-connective role in AD. The present review emphasizes key molecular pathways that correlate the role of insulin with Nrf2 during AD. The review has also identified key unexplored areas that could be investigated in future to further establish the insulin and Nrf2 influence in AD.

Application of Marine Natural Products against Alzheimer's Disease: Past, Present and Future

Alzheimer's disease (AD), a neurodegenerative disease, is one of the most intractable illnesses which affects the elderly. Clinically manifested as various impairments in memory, language, cognition, visuospatial skills, executive function, etc., the symptoms gradually aggravated over time. The drugs currently used clinically can slow down the deterioration of AD and relieve symptoms but cannot completely cure them. The drugs are mainly acetylcholinesterase inhibitors (AChEI) and non-competitive N-methyl-D-aspartate receptor (NDMAR) antagonists. The pathogenesis of AD is inconclusive, but it is often associated with the expression of beta-amyloid. Abnormal deposition of amyloid and hyperphosphorylation of tau protein in the brain have been key targets for past, current, and future drug development for the disease. At present, researchers are paying more and more attention to excavate natural compounds which can be effective against Alzheimer's disease and other neurodegenerative pathologies. Marine natural products have been demonstrated to be the most prospective candidates of these compounds, and some have presented significant neuroprotection functions. Consequently, we intend to describe the potential effect of bioactive compounds derived from marine organisms, including polysaccharides, carotenoids, polyphenols, sterols and alkaloids as drug candidates, to further discover novel and efficacious drug compounds which are effective against AD.

Antiparkinsonian Agents in Investigational Polymeric Micro- and Nano-Systems

Parkinson's disease (PD) is a devastating neurodegenerative disease characterized by progressive destruction of dopaminergic tissue in the central nervous system (CNS). To date, there is no cure for the disease, with current pharmacological treatments aimed at controlling the symptoms. Therefore, there is an unmet need for new treatments for PD. In addition to new therapeutic options, there exists the need for improved efficiency of the existing ones, as many agents have difficulties in crossing the blood-brain barrier (BBB) to achieve therapeutic levels in the CNS or exhibit inappropriate pharmacokinetic profiles, thereby limiting their clinical benefits. To overcome these limitations, an interesting approach is the use of drug delivery systems, such as polymeric microparticles (MPs) and nanoparticles (NPs) that allow for the controlled release of the active ingredients targeting to the desired site of action, increasing the bioavailability and efficacy of treatments, as well as reducing the number of administrations and adverse effects. Here we review the polymeric micro- and nano-systems under investigation as potential new therapies for PD.

Biomaterial and Therapeutic Approaches for the Manipulation of Macrophage Phenotype in Peripheral and Central Nerve Repair

Injury to the peripheral or central nervous systems often results in extensive loss of motor and sensory function that can greatly diminish quality of life. In both cases, macrophage infiltration into the injury site plays an integral role in the host tissue inflammatory response. In particular, the temporally related transition of macrophage phenotype between the M1/M2 inflammatory/repair states is critical for successful tissue repair. In recent years, biomaterial implants have emerged as a novel approach to bridge lesion sites and provide a growth-inductive environment for regenerating axons. This has more recently seen these two areas of research increasingly intersecting in the creation of 'immune-modulatory' biomaterials. These synthetic or naturally derived materials are fabricated to drive macrophages towards a pro-repair phenotype. This review considers the macrophage-mediated inflammatory events that occur following nervous tissue injury and outlines the latest developments in biomaterial-based strategies to influence macrophage phenotype and enhance repair.

Towards clinical translation of 'second-generation' regenerative stroke therapies: hydrogels as game changers?

Stroke is an unmet clinical need with a paucity of treatments, at least in part because chronic stroke pathologies are prohibitive to 'first-generation' stem cell-based therapies. Hydrogels can remodel the hostile stroke microenvironment to aid endogenous and exogenous regenerative repair processes. However, no clinical trials have yet been successfully commissioned for these 'second-generation' hydrogel-based therapies for chronic ischaemic stroke regeneration. This review recommends a path forward to improve hydrogel technology for future clinical translation for stroke. Specifically, we suggest that a better understanding of human host stroke tissue-hydrogel interactions in addition to the effects of scaling up hydrogel volume to human-sized cavities would help guide translation of these second-generation regenerative stroke therapies.

Amino acid-functionalized chitosan beads for in vitro copper ions uptake in the presence of histidine

One of the hallmarks of Alzheimer's Disease (AD) is the anomalous binding involving amyloid-β (Aβ) peptide and metal ions, such as copper, formed through histidine (His) residues. Herein, adsorption experiments were performed to test the in vitro ability of chitosan to uptake copper ions in the presence of histidine. The characterization of the beads was assessed before and after the adsorption process by scanning electron microscope, X-ray diffraction and Fourier-transform infrared spectroscopy. Amino acid functionalization of chitosan-based beads promoted an increase in the copper ions adsorption capacity (2.47 mmol of Cu(II)/gram of adsorbent). Nevertheless, depending on the order of addition of histidine to the system, different adsorption behaviors were observed. The kinetics showed that, once the Cu(II)-His bond was established, functionalized beads were less efficient to capture Cu(II), which promoted a decrease in the overall adsorption capacity. However, when chitosan and histidine were simultaneously added to the Cu(II) solution, there was no decrease in adsorption capacity. To sum up, chitosan-based materials are an interesting model to provide a better understanding on the biomolecules‑copper interactions that occur in AD, as well as a possible chelating agent that can interfere in the bonds between Aβ residues and copper ions.

Galantamine nanoparticles outperform oral galantamine in an Alzheimer's rat model: pharmacokinetics and pharmacodynamics

Aim: Galantamine is an acetylcholinesterase inhibitor frequently used in Alzheimer's disease management. Its cholinergic adverse effects and rapid elimination limit its therapeutic outcomes. We investigated the pharmacodynamics and pharmacokinetics of 2-week intranasal galantamine-bound chitosan nanoparticles (G-NP) treatment in scopolamine-induced Alzheimer's disease rat model. Materials & methods: Behavioral, neurobiochemical and histopathological changes were assessed and compared with oral and nasal solutions. Brain uptake and pharmacokinetics were determined using a novel validated LC/MS assay. Results: G-NP enhanced spatial memory, exploring behavior and cholinergic transmission in rats. Beta-amyloid deposition and Notch signaling were suppressed and the histopathological degeneration was restored. G-NP potentiated galantamine brain delivery and delayed its elimination. Conclusion: G-NP hold promising therapeutic potentials and brain targeting, outperforming conventional galantamine therapy.

β-Asarone Ameliorates β-Amyloid-Induced Neurotoxicity in PC12 Cells by Activating P13K/Akt/Nrf2 Signaling Pathway

Accumulation of β-amyloid (Aβ) causes oxidative stress, which is the major pathological mechanism in Alzheimer's disease (AD). β-asarone could reduce Aβ-induced oxidative stress and neuronal damage, but the molecular mechanism remains elusive. In this study, we used an Aβ-stimulated PC12 cell model to explore the neuroprotective effects and potential mechanisms of β-asarone. The results showed that β-asarone could improve cell viability and weaken cell damage and apoptosis. β-asarone could also decrease the level of ROS and MDA; increase the level of SOD, CAT, and GSH-PX; and ameliorate the mitochondrial membrane potential. Furthermore, β-asarone could promote the expression of Nrf2 and HO-1 by upregulating the level of PI3K/Akt phosphorylation. In conclusion, β-asarone could exert neuroprotective effects by modulating the P13K/Akt/Nrf2 signaling pathway. β-asarone might be a promising therapy for AD.

Effects of vanillic acid on Aβ1-40-induced oxidative stress and learning and memory deficit in male rats

Alzheimer's disease (AD) is a neurodegenerative disease, in which the accumulation of β-amyloid (Aβ) peptide in the extracellular space causes a progressive reduction in cognitive performance. Aβ stimulates active oxygen species generation leading to oxidative stress and neural cell death. Vanillic Acid (VA) is the oxidant form of vanillin widely found in vanilla beans. VA has many properties, such as suppressing apoptosis and eliminating the harmful effects of oxidative stress in animal models. The VA effects on impaired learning and memory in Aβ rats were assessed. Forty adults male Wistar rats were assigned to the following five groups in random: the control, sham (received saline (vehicle) via intracerebroventricular (ICV) injection), Aβ (received Aβ1-40 via ICV injection), VA (50 mg/kg by oral gavage once a day through four weeks), and Aβ + VA (50 mg/kg) groups. Open field test, novel object recognition (NOR) test, Morris water maze (MWM) test, and passive avoidance learning (PAL) task were performed, and finally, we determined the malondialdehyde (MDA), total antioxidant capacity (TAC) and total oxidant status (TOS) levels. Aβ decreased the cognitive memory in NOR, spatial memory in MWM, and passive avoidance memory in PAL tests. In contrast, VA improved learning and memory in the treated group. Aβ significantly increased MDA and TOS and decreased TAC levels, whereas VA treatment significantly reversed TAC, TOS and MDA levels. In conclusion, VA decreased the Aβ effects on learning and memory by suppressing oxidative stress and can be regarded as a neuroprotective substance in AD.

Formulation, optimization and characterization of allantoin-loaded chitosan nanoparticles to alleviate ethanol-induced gastric ulcer: in-vitro and in-vivo studies

Allantoin (ALL) is a phytochemical possessing an impressive array of biological activities. Nonetheless, developing a nanostructured delivery system targeted to augment the gastric antiulcerogenic activity of ALL has not been so far investigated. Consequently, in this survey, ALL-loaded chitosan/sodium tripolyphosphate nanoparticles (ALL-loaded CS/STPP NPs) were prepared by ionotropic gelation technique and thoroughly characterized. A full 24 factorial design was adopted using four independently controlled parameters (ICPs). Comprehensive characterization, in vitro evaluations as well as antiulcerogenic activity study against ethanol-induced gastric ulcer in rats of the optimized NPs formula were conducted. The optimized NPs formula, (CS (1.5% w/v), STPP (0.3% w/v), CS:STPP volume ratio (5:1), ALL amount (13 mg)), was the most convenient one with drug content of 6.26 mg, drug entrapment efficiency % of 48.12%, particle size of 508.3 nm, polydispersity index 0.29 and ζ-potential of + 35.70 mV. It displayed a sustained in vitro release profile and mucoadhesive strength of 45.55%. ALL-loaded CS/STPP NPs (F-9) provoked remarkable antiulcerogenic activity against ethanol-induced gastric ulceration in rats, which was accentuated by histopathological, immunohistochemical (IHC) and biochemical studies. In conclusion, the prepared ALL-loaded CS/STPP NPs could be presented to the phytomedicine field as an auspicious oral delivery system for gastric ulceration management.

Chitosan nanoparticles enhance developmental competence of in vitro-matured porcine oocytes

Oxidative stress is inevitable as it is derived from the handling, culturing, inherent metabolic activities and medium supplementation of embryos. This study was performed to investigate the protective effect of chitosan nanoparticles (CNPs) on oxidative damage in porcine oocytes. For this purpose, cumulus-oocyte complexes (COCs) derived from porcine slaughterhouse ovaries were exposed to different concentrations of CNPs (0, 10, 25 and 50 µg/ml) during in vitro maturation (IVM). Oocytes treated with 25 µg/ml CNPs showed significantly higher levels of GSH, along with a significant reduction in ROS levels compared to control, CNPs10 and CNPs50 groups. In parthenogenetic embryo production, the maturation rate was significantly higher in the CNPs25 group than that in the control and all other treated groups. In addition, when compared to the CNPs50 and control groups, CNPs25-treated oocytes showed significantly higher cleavage and blastocyst development rates. The highest concentration of CNPs reduced the total cell number and ratio of ICM: TE cells in parthenogenetic embryos, suggesting that there is a threshold where benefits are lost if exceeded. In cloned embryos, the CNPs25 group, as compared to all other treated groups, showed significantly higher maturation and cleavage rates. Furthermore, the blastocyst development rate in the CNPs25-treated group was significantly higher than that in the CNPs50-treated group, as was the total cell number. Moreover, we found that cloned embryos derived from the CNPs25-treated group showed significantly higher expression levels of Pou5f1, Dppa2, and Ndp52il genes, compared with those of the control and other treated groups. Our results demonstrated that 25 µg/ml CNPs treatment during IVM improves the developmental competence of porcine oocytes by reducing oxidative stress.

The effects of chitosan-based materials on glioma: Recent advances in its applications for diagnosis and treatment

Glioma is known as the most common primary brain tumor occurring in adolescents and is considered as a lethal disease worldwide. Despite the advancements in presently available therapeutic approaches (i.e. radiation therapy and chemotherapy), the rate of amelioration in glioma patients is still low. In this regard, it seems that there is a need for reconsidering and enhancing current therapies and/or discovering novel therapeutic platforms. Chitosan is a natural polysaccharide with several beneficial characteristics, including biocompatibility, biodegradability, and low toxicity. Without causing toxic effects on healthy cells, chitosan nanoparticles are attractive targets in cancer therapy which lead to the sustained release and enhanced internalization of chemotherapeutic drugs as well as higher cytotoxicity for cancer cells. Hence, these properties turn it into a suitable candidate for the treatment of various cancers, including glioma. In the viewpoint of glioma, cancer inhibition is possible through targeting glioma-associated signaling pathways and molecules such as MMP-9, VEGF, TRAIL and nuclear factor-κB by chitosan and its derivatives. Moreover, it has been acknowledged that chitosan and its derivatives can be applied as a delivery system for carrying a diverse range of therapeutic agents to the tumor site. Besides the anti-glioma effects of chitosan and its derivatives, these molecules can be utilized for culturing glioma cancer cells; providing a better understanding of glioma pathogenesis. Furthermore, it is documented that 3D chitosan scaffolds are potential targets that offer advantageous drug screening platforms. Herein, we summarized the anti-glioma effects of chitosan and also its utilization as drug delivery systems in the treatment of glioma.

Attenuation of Nrf2/Keap1/ARE in Alzheimer's Disease by Plant Secondary Metabolites: A Mechanistic Review

Alzheimer’s disease (AD) is a progressive neuronal/cognitional dysfunction, leading to disability and death. Despite advances in revealing the pathophysiological mechanisms behind AD, no effective treatment has yet been provided. It urges the need for finding novel multi-target agents in combating the complex dysregulated mechanisms in AD. Amongst the dysregulated pathophysiological pathways in AD, oxidative stress seems to play a critical role in the pathogenesis progression of AD, with a dominant role of nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein-1 (Keap1)/antioxidant responsive elements (ARE) pathway. In the present study, a comprehensive review was conducted using the existing electronic databases, including PubMed, Medline, Web of Science, and Scopus, as well as related articles in the field. Nrf2/Keap1/ARE has shown to be the upstream orchestrate of oxidative pathways, which also ameliorates various inflammatory and apoptotic pathways. So, developing multi-target agents with higher efficacy and lower side effects could pave the road in the prevention/management of AD. The plant kingdom is now a great source of natural secondary metabolites in targeting Nrf2/Keap1/ARE. Among natural entities, phenolic compounds, alkaloids, terpene/terpenoids, carotenoids, sulfur-compounds, as well as some other miscellaneous plant-derived compounds have shown promising future accordingly. Prevailing evidence has shown that activating Nrf2/ARE and downstream antioxidant enzymes, as well as inhibiting Keap1 could play hopeful roles in overcoming AD. The current review highlights the neuroprotective effects of plant secondary metabolites through targeting Nrf2/Keap1/ARE and downstream interconnected mediators in combating AD.

Use of Biodegradable, Chitosan-Based Nanoparticles in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects more than 24 million people worldwide and represents an immense medical, social and economic burden. While a vast array of active pharmaceutical ingredients (API) is available for the prevention and possibly treatment of AD, applicability is limited by the selective nature of the blood-brain barrier (BBB) as well as by their severe peripheral side effects. A promising solution to these problems is the incorporation of anti-Alzheimer drugs in polymeric nanoparticles (NPs). However, while several polymeric NPs are nontoxic and biocompatible, many of them are not biodegradable and thus not appropriate for CNS-targeting. Among polymeric nanocarriers, chitosan-based NPs emerge as biodegradable yet stable vehicles for the delivery of CNS medications. Furthermore, due to their mucoadhesive character and intrinsic bioactivity, chitosan NPs can not only promote brain penetration of drugs via the olfactory route, but also act as anti-Alzheimer therapeutics themselves. Here we review how chitosan-based NPs could be used to address current challenges in the treatment of AD; with a specific focus on the enhancement of blood-brain barrier penetration of anti-Alzheimer drugs and on the reduction of their peripheral side effects.

Chitosan-Ellagic Acid Nanohybrid for Mitigating Rotenone-induced Oxidative Stress

Antioxidants derived from nature, such as ellagic acid (EA), demonstrated high potency to mitigate neuronal oxidative stress and related pathologies, including Parkinson's disease. However, the application of EA is limited due to its toxicity at moderate doses and poor solubility, cellular permeability, and bioavailability. Here, we introduce a sustainably resourced, green nanoencasement strategy to overcome the limitations of EA and derive synergistic effects to prevent oxidative stress in neuronal cells. Chitosan, with its high biocompatibility, potential antioxidant properties, and flexible surface chemistry, was chosen as the primary component of the nanoencasement in which EA is immobilized. Using a rotenone model to mimic intracellular oxidative stress, we examined the effectiveness of EA and chitosan to limit cell death. Our studies indicate a synergistic effect between EA and chitosan in mitigating rotenone-induced reactive oxygen species death. Our analysis suggests that chitosan encapsulation of EA reduces the inherent cytotoxicity of the polyphenol (a known anticancer molecule). Furthermore, its encapsulation permits its delivery via a rapid burst phase and a relatively slow phase making the nanohybrid suitable for drug release over extended time periods.

miR-2703 regulates the chitin biosynthesis pathway by targeting chitin synthase 1a in Nilaparvata lugens

The chitin biosynthesis pathway is an important physiology process in arthropods. However, few microRNAs (miRNAs) involved in the regulation of the chitin biosynthesis pathway in insects have been reported until now. In this study, four groups of samples that either upregulated or downregulated the chitin biosynthesis pathway were collected for deep sequencing, and a total of 15 unique mature miRNAs with significantly different expression levels were found, including 11 known miRNAs and four novel miRNAs. Subsequently, we showed that miR-2703 and its new target gene chitin synthase 1a are important for ecdysone-induced chitin biosynthesis in Nilaparvata lugens, a serious insect pest of rice. The nymphs showed an obvious moulting defect phenotype, lower survival rate and significantly reduced chitin content after miR-2703 feeding or injection. Furthermore, we found that the transcription level of miR-2703 was not repressed by 20-hydroxyecdysone signalling after Broad-Complex (BR-C) double-stranded RNA (dsRNA) injection compared with the repressed levels after green fluorescent protein dsRNA injection, suggesting that the involvement of miR-2703 in the 20-hydroxyecdysone pathway contributes to BR-C activity. miR-2703 regulates the chitin biosynthesis pathway by targeting chitin synthase 1a in response to 20-hydroxyecdysone signalling.

Chitosan oligosaccharide inhibits skull resorption induced by lipopolysaccharides in mice

Background

Low-molecular-weight chitosan oligosaccharide (LMCOS), a chitosan degradation product, is water-soluble and easily absorbable, rendering it a popular biomaterial to study. However, its effect on bone remodelling remains unknown. Therefore, we evaluated the effect of LMCOS on lipopolysaccharide (LPS)-induced bone resorption in mice.

Methods

Six-week-old male C57BL/6 mice (n = five per group) were randomly divided into five groups: PBS, LPS, LPS + 0.005% LMCOS, LPS + 0.05% LMCOS, and LPS + 0.5% LMCOS. Then, the corresponding reagents (300 μL) were injected into the skull of the mice. To induce bone resorption, LPS was administered at 10 mg/kg per injection. The mice were injected three times a week with PBS alone or LPS without or with LMCOS and sacrificed 2 weeks later. The skull was removed for micro-computed tomography, haematoxylin-eosin staining, and tartrate-resistant acid phosphatase staining. The area of bone damage and osteoclast formation were evaluated and recorded.

Results

LMCOS treatment during LPS-induced skull resorption led to a notable reduction in the area of bone destruction; we observed a dose-dependent decrease in the area of bone destruction and number of osteoclasts with increasing LMCOS concentration.

Conclusions

Our findings showed that LMCOS could inhibit skull bone damage induced by LPS in mice, further research to investigate its therapeutic potential for treating osteolytic diseases is required.

Treatment of hepatotoxicity induced by γ-radiation using platelet-rich plasma and/or low molecular weight chitosan in experimental rats

Background and aim: Platelet-rich plasma (PRP) is rich in growth factors and plays an important role in tissue healing and cytoprotection. Also, it has been proved that low molecular weight chitosan (LMC) possesses many outstanding health benefits. The aim of this study was to assess the possibility of using PRP and/or fungal LMC to treat hepatotoxicity induced by γ-radiation in albino rats.Materials and methods: Forty-eight adult male albino rats were randomly divided into eight groups. Group I (control), Group II (PRP alone), Group III (LMC alone), Group IV (PRP + LMC), Group V (γ-irradiated alone), Group VI (γ-irradiated + PRP), Group VII (γ-irradiated + LMC), and Group VIII (γ-irradiated + PRP + LMC). The irradiated rats were whole body exposed to γ-radiation (8 Gy) as fractionated doses (2 Gy) twice a week for 2 consecutive weeks. The treated groups received PRP (0.5 mL/kg body weight, s.c.) and/or LMC (10 mg/kg body weight, s.c.) 2 days a week 1 h after every dose of γ-radiation and continued for another week after the last dose of radiation. Serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, as well as reduced glutathione (GSH) content, malondialdehyde (MDA), total antioxidant capacity (TAC), and nuclear factor erythroid 2-related factor 2 (Nrf2) levels in the liver tissue and relative expression of microRNA-21 (miR-21) in serum were measured, in addition to histopathological examination.Results: Exposure of rats to γ-radiation resulted in a significant increase in serum ALT and AST activities, hepatic MDA levels, and serum miR-21 relative expression, along with a significant decrease in hepatic GSH content, TAC, and Nrf2 levels. Treatment with PRP and/or fungal LMC after exposure to γ-radiation ameliorated these parameters and improved the histopathological changes induced by γ-radiation.Conclusions: The results demonstrated that PRP and/or LMC inhibited γ-radiation-induced hepatotoxicity and using both of them together seems more effective. They can be a candidate to be studied toward the development of a therapeutic strategy for liver diseases.

Copper Ion Uptake by Chitosan in the Presence of Amyloid-β and Histidine

Alzheimer's disease (AD) is related to the anomalous binding that occurs between amyloid-β peptide (Aβ) and copper ion, through imidazole ring of histidine (His), as stated in the literature. It is also known that high-affinity metal ion chelators can be pharmacologically used as a possible therapeutic approach. In this work, we tested the ability "in vitro" of chitosan (Chi) to reduce Aβ aggregation and Thioflavin T binding assay indicated that chitosan has affinity for Aβ and interferes in its aggregation. We also tested the ability of Chi to uptake copper ions in the presence of Aβ or His. Equilibrium data reveals that chitosan acted as an effective chelating agent competing with Aβ and histidine for copper binding. The addition of histidine or Aβ in the system promotes an unfolding of chitosan chains, as verified by small-angle X-ray scattering. Extended X-ray absorption fine structure and XPS spectra show that new copper interactions with groups containing nitrogen in the presence of histidine may occur. These results can help understanding fundamental chemical interactions among species detected in AD and biopolymers, opening up possibilities for new treatment approaches for this disease.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

Chitosan oligosaccharides prevent doxorubicin-induced oxidative stress and cardiac apoptosis through activating p38 and JNK MAPK mediated Nrf2/ARE pathway

Doxorubicin (DOX) is one of the most effective chemotherapeutic drugs; however, the incidence of cardiotoxicity compromises its therapeutic index. Oxidative stress and apoptosis are believed to be involved in DOX-induced cardiotoxicity. Chitosan oligosaccharides (COS), the enzymatic hydrolysates of chitosan, have been reported to possess diverse biological activities including antioxidant and anti-apoptotic properties. The objective of the present study was to investigate the potential role of COS against DOX-induced cardiotoxicity, and the effects of COS on apoptosis and oxidative stress in rats and H9C2 cells. Furthermore, we also shed light on the involved pathways during the whole process. For this purpose, first, we demonstrated that COS exhibited a significant protective effect on cardiac tissue by not only inducing a decrease in body and heart growth but also ameliorated oxidative damage and ECG alterations in DOX-treated rats. Second, we found that COS reversed the decrease of cell viability induced by DOX, reduced the intracellular reactive oxygen species (ROS), increased the mitochondrial membrane potential (MMP) and Bcl-2/Bax ratio. COS treatment also results in reduced caspase-3 and caspase-9 expressions, and an increase in the phosphorylation of MAPKs (mitogen-activated protein kinases) in DOX-exposed H9C2 cells. Additionally, cellular homeostasis was re-established via stabilization of MAPK mediated nuclear factor erythroid 2-related factor 2/antioxidant-response element (Nrf2/ARE) signaling and transcription of downstream cytoprotective genes. In summary, these findings suggest that COS could be a potential candidate for the prevention and treatment of DOX-induced cardiotoxicity.

Collagen peptide modified carboxymethyl cellulose as both antioxidant drug and carrier for drug delivery against retinal ischaemia/reperfusion injury

Oxidative stress can cause injury in retinal endothelial cells. Carboxymethyl cellulose modified with collagen peptide (CMCC) is of a distinct antioxidant capacity and potentially a good drug carrier. In this study, the protective effects of CMCC against H2 O2 -induced injury of primary retinal endothelial cells were investigated. In vitro, we demonstrated that CMCC significantly promoted viability of H2 O2 -treated cells, efficiently restrained cellular reactive oxygen species (ROS) production and cell apoptosis. Then, the CMCC was employed as both drug and anti-inflammatory drug carrier for treatment of retinal ischaemia/reperfusion (I/R) in rats. Animals were treated with CMCC or interleukin-10-loaded CMCC (IL-10@CMCC), respectively. In comparisons, the IL-10@CMCC treatment exhibited superior therapeutic effects, including better restoration of retinal structural thickness and less retinal apoptosis. Also, chemiluminescence demonstrated that transplantation of IL-10@CMCC markedly reduced the retinal oxidative stress level compared with CMCC alone and potently recovered the activities of typical antioxidant enzymes, SOD and CAT. Therefore, it could be concluded that CMCC provides a promising platform to enhance the drug-based therapy for I/R-related retinal injury.

Silencing of PHLPP1 promotes neuronal apoptosis and inhibits functional recovery after spinal cord injury in mice

AIM

Spinal cord injury (SCI) causes increased apoptosis of neurons, leading to irreversible dysfunction of the spinal cord. In this study, we investigated the effects of the progression of SCI and potential regulation of apoptosis after the Pleckstrin homology (PH) domain and leucine rich repeat protein phosphatase 1 (PHLPP1) gene was silenced.

MAIN METHODS

Spinal cord injection, and neuronal transfection with a recombinant adenovirus vector encoding small interfering RNA (siRNA) against PHLPP1 (AdsiPHLPP1) successfully silenced PHLPP1. These created in vivo and in vitro PHLPP1-silenced models, respectively, resulting in stable expression of the transgene in neurons.

KEY FINDINGS

The results showed that silencing of PHLPP1 evidently reduced levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) after SCI. Western blot analysis revealed that the mice injected with AdsiPHLPP1 showed increased the expression of pro-apoptotic factors (Bax and cleaved-caspase 3), and reduced levels of neurotrophic (BDNF) and anti-apoptotic (Bcl-2) factors, both in vivo and in vitro. The motor function of AdsiPHLPP1-injected mice was restored more slowly than that of wild type (WT) mice. In addition, the number of motor neurons surviving in the anterior horn of the spinal cord was also reduced after SCI.

SIGNIFICANCE

Our results confirm that silencing of PHLPP1 promotes neuronal apoptosis and inhibits functional recovery after injury in vivo and in vitro. Consequently, PHLPP1 represents a potential therapeutic target gene for the clinical treatment of SCI.

Rutin as a Potent Antioxidant: Implications for Neurodegenerative Disorders

A wide range of neurodegenerative diseases (NDs), including Alzheimer's disease, Parkinson's disease, Huntington's disease, and prion diseases, share common mechanisms such as neuronal loss, apoptosis, mitochondrial dysfunction, oxidative stress, and inflammation. Intervention strategies using plant-derived bioactive compounds have been offered as a form of treatment for these debilitating conditions, as there are currently no remedies to prevent, reverse, or halt the progression of neuronal loss. Rutin, a glycoside of the flavonoid quercetin, is found in many plants and fruits, especially buckwheat, apricots, cherries, grapes, grapefruit, plums, and oranges. Pharmacological studies have reported the beneficial effects of rutin in many disease conditions, and its therapeutic potential in several models of NDs has created considerable excitement. Here, we have summarized the current knowledge on the neuroprotective mechanisms of rutin in various experimental models of NDs. The mechanisms of action reviewed in this article include reduction of proinflammatory cytokines, improved antioxidant enzyme activities, activation of the mitogen-activated protein kinase cascade, downregulation of mRNA expression of PD-linked and proapoptotic genes, upregulation of the ion transport and antiapoptotic genes, and restoration of the activities of mitochondrial complex enzymes. Taken together, these findings suggest that rutin may be a promising neuroprotective compound for the treatment of NDs.

Potentiation effect on accelerating diabetic wound healing using 2-N,6-O-sulfated chitosan-doped PLGA scaffold

Accelerating the wound healing of diabetes-impaired cutaneous tissue is still a challenge due to the aberrant cellular behavior, poor angiogenesis, and pathological micro-environment. Activation with growth factors and modulation of the redox micro-environment of the diabetic wound are considered to be effective strategies. Herein, we have described a highly sulfated heparin-like polysaccharide 2-N, 6-O-sulfated chitosan (26SCS)-doped poly(lactic-co-glycolic acid) scaffold (S-PLGA), which can achieve controlled and sustained release of heparin-binding epidermal growth factor (HB-EGF) owing to its affinity for heparin-binding growth factors. Interestingly, the antioxidant effect of 26SCS was confirmed and it was shown to have a strong scavenging activity towards superoxide radicals, a moderate scavenging activity towards hydroxyl radicals and a lower scavenging activity towards hydrogen peroxide. It also exhibited stronger protective effects in a human keratinocyte cell line (Ha-cat) against H₂O₂-induced oxidative damage. The Ha-cat cells cultured in the presence of the S-PLGA scaffold were significantly protected against oxidative stress during proliferation. In a full thickness excisional wound model of a diabetic rat, the wound treated with the HB-EGF-loaded S-PLGA scaffold was basically healed after 28 days. Conversely, the wounds in the other diabetic groups were not closed. The migration effect of the keratinocytes was enhanced by the 26SCS-induced sustainable release of HB-EGF and the scavenging of ROS which led to rapid re-epithelialization. Furthermore, histopathological evaluation demonstrated the positive effects on wound contraction, epithelial regeneration, and collagen deposition when treated with the HB-EGF loaded S-PLGA scaffold. These findings highlight that 26SCS may serve as a promising coagent for both controlled release of growth factors and alleviation of excessive ROS production, thus leading to increased regeneration of the diabetic wounds.

Biomaterials for revascularization and immunomodulation after spinal cord injury

Spinal cord injury (SCI) causes immediate damage to the nervous tissue accompanied by loss of motor and sensory function. The limited self-repair competence of injured nervous tissue underscores the need for reparative interventions to recover function after SCI. The vasculature of the spinal cord plays a crucial role in SCI and repair. Ruptured and sheared blood vessels in the injury epicenter and blood vessels with a breached blood-spinal cord barrier (BSCB) in the surrounding tissue cause bleeding and inflammation, which contribute to the overall tissue damage. The insufficient formation of new functional vasculature in and near the injury impedes endogenous tissue repair and limits the prospect of repair approaches. Limiting the loss of blood vessels, stabilizing the BSCB, and promoting the formation of new blood vessels are therapeutic targets for spinal cord repair. Inflammation is an integral part of injury-mediated vascular damage, which has deleterious and reparative consequences. Inflammation and the formation of new blood vessels are intricately interwoven. Biomaterials can be effectively used for promoting and guiding blood vessel formation or modulating the inflammatory response after SCI, thereby governing the extent of damage and the success of reparative interventions. This review deals with the vasculature after SCI, the reciprocal interactions between inflammation and blood vessel formation, and the potential of biomaterials to support revascularization and immunomodulation in damaged spinal cord nervous tissue.

Amentoflavone Ameliorates Aβ1-42-Induced Memory Deficits and Oxidative Stress in Cellular and Rat Model

Alzheimer's disease (AD), a progressive neurodegenerative disease of the central nervous system, is the most common cause of senile dementia. This study aimed to investigate whether amentoflavone (AF), a biflavonoid compound, could exert neuroprotective activities against AD. The AD model was established by the intracranial injection of amyloid-beta (Aβ) in rat models. The effect of AF on cognitive function was examined using the Morris water maze test. Cell survival and apoptosis in the hippocampal region in an animal model were detected using Nissl staining and a terminal deoxynucleotidyl transferased UTP nick-end labeling assay, respectively. The levels of oxidant enzymes were determined by enzyme-linked immunosorbent assay. Signaling molecule expressions were examined by western blotting. Our results showed that AF significantly attenuated Aβ-induced deficits in neurological functions as well as neuronal cell death and apoptosis in the hippocampal region. Moreover, our findings revealed that AF increased nuclear factor erythroid 2-related factor 2 (Nrf2) expression and translocation and activated AMP-activated protein kinase (AMPK) signaling. In a cellular model of AD established by exposing PC12 cells to Aβ, our results provided further evidence that the neuroprotective activities of AF were mediated by modulating Nrf2 through AMPK/glycogen synthase kinase 3 beta signaling. AF exerts a protective effect against Aβ_1-42-induced neurotoxcicity by inducing Nrf2 antioxidant pathways via AMPK signaling activation, which provided experimental evidence that AF might provide a clinical benefit to patients with AD.

Heat Shock Proteins and Autophagy Pathways in Neuroprotection: from Molecular Bases to Pharmacological Interventions

Neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease and Huntington's disease (HD), amyotrophic lateral sclerosis, and prion diseases are all characterized by the accumulation of protein aggregates (amyloids) into inclusions and/or plaques. The ubiquitous presence of amyloids in NDDs suggests the involvement of disturbed protein homeostasis (proteostasis) in the underlying pathomechanisms. This review summarizes specific mechanisms that maintain proteostasis, including molecular chaperons, the ubiquitin-proteasome system (UPS), endoplasmic reticulum associated degradation (ERAD), and different autophagic pathways (chaperon mediated-, micro-, and macro-autophagy). The role of heat shock proteins (Hsps) in cellular quality control and degradation of pathogenic proteins is reviewed. Finally, putative therapeutic strategies for efficient removal of cytotoxic proteins from neurons and design of new therapeutic targets against the progression of NDDs are discussed.

Application of Chitosan, Chitooligosaccharide, and Their Derivatives in the Treatment of Alzheimer's Disease

Classic hypotheses of Alzheimer's disease (AD) include cholinergic neuron death, acetylcholine (ACh) deficiency, metal ion dynamic equilibrium disorder, and deposition of amyloid and tau. Increased evidence suggests neuroinflammation and oxidative stress may cause AD. However, none of these factors induces AD independently, but they are all associated with the formation of Aβ and tau proteins. Current clinical treatments based on ACh deficiency can only temporarily relieve symptoms, accompanied with many side-effects. Hence, searching for natural neuroprotective agents, which can significantly improve the major symptoms and reverse disease progress, have received great attention. Currently, several bioactive marine products have shown neuroprotective activities, immunomodulatory and anti-inflammatory effects with low toxicity and mild side effects in laboratory studies. Recently, chitosan (CTS), chitooligosaccharide (COS) and their derivatives from exoskeletons of crustaceans and cell walls of fungi have shown neuroprotective and antioxidative effects, matrix metalloproteinase inhibition, anti-HIV and anti-inflammatory properties. With regards to the hypotheses of AD, the neuroprotective effect of CTS, COS, and their derivatives on AD-like changes in several models have been reported. CTS and COS exert beneficial effects on cognitive impairments via inhibiting oxidative stress and neuroinflammation. They are also a new type of non-toxic β-secretase and AChE inhibitor. As neuroprotective agents, they could reduce the cell membrane damage caused by copper ions and decrease the content of reactive oxygen species. This review will focus on their anti-neuroinflammation, antioxidants and their inhibition of β-amyloid, acetylcholinesterase and copper ions adsorption. Finally, the limitations and future work will be discussed.

Stability and bioactivity of chitosan as a transfection agent in primary human cell cultures: A case for chitosan-only controls

Chitosan polymers (Cs), from which microparticles (CsM) may be precipitated to deliver various intracellular payloads, are generally considered biologically inert. We examined the impact of cell culture conditions on CsM size and the effect of chitosan on CD59 expression in primary human smooth muscle cells. We found that particle concentration and incubation time in biological buffers augmented particle size. Between pH 7.0 and pH 7.5, CsM size increased abruptly. We utilized CsM containing a plasmid with a gene for CD59 (pCsM) to transfect cells. Both CD59 mRNA and the number of CD59-positive cells were increased after pCsM treatment. Unexpectedly, CsM also augmented the number of CD59-positive cells. Cs alone enhanced CD59 expression more potently than either pCSM or CsM. This observation strongly suggests that chitosan is in fact bioactive and that chitosan-only controls should be included to avoid misattributing the activity of the delivery agent with that of the payload.

Ex Vivo and In Vivo Characterization of Interpolymeric Blend/Nanoenabled Gastroretentive Levodopa Delivery Systems

One approach for delivery of narrow absorption window drugs is to formulate gastroretentive drug delivery systems. This study was undertaken to provide insight into in vivo performances of two gastroretentive systems (PXLNET and IPB matrices) in comparison to Madopar® HBS capsules. The pig model was used to assess gastric residence time and pharmacokinetic parameters using blood, cerebrospinal fluid (CSF), and urine samples. Histopathology and cytotoxicity testing were also undertaken. The pharmacokinetic parameters indicated that levodopa was liberated from the drug delivery systems, absorbed, widely distributed, metabolized, and excreted. C_max were 372.37, 257.02, and 461.28 ng/mL and MRT were 15.36, 14.98, and 13.30 for Madopar HBS capsules, PXLNET, and IPB, respectively. In addition, X-ray imaging indicated that the gastroretentive systems have the potential to reside in the stomach for 7 hours. There was strong in vitro-in vivo correlation for all formulations with r² values of 0.906, 0.935, and 0.945 for Madopar HBS capsules, PXLNET, and IPB, respectively. Consequently, PXLNET and IPB matrices have pertinent potential as gastroretentive systems for narrow absorption window drugs (e.g., L-dopa) and, in this application specifically, enhanced the central nervous system and/or systemic bioavailability of such drugs.

An Overview of the Protective Effects of Chitosan and Acetylated Chitosan Oligosaccharides against Neuronal Disorders

Chitin is the second most abundant biopolymer on Earth and is mainly comprised of a marine invertebrate, consisting of repeating β-1,4 linked N-acetylated glucosamine units, whereas its N-deacetylated product, chitosan, has broad medical applications. Interestingly, chitosan oligosaccharides have therapeutic effects on different types of neuronal disorders, including, but not limited to, Alzheimer’s disease, Parkinson’s disease, and nerve crush injury. A common link among neuronal disorders is observed at a sub-cellular level, such as atypical protein assemblies and induced neuronal death. Chronic activation of innate immune responses that lead to neuronal injury is also common in these diseases. Thus, the common mechanisms of neuronal disorders might explain the general therapeutic effects of chitosan oligosaccharides and their derivatives in these diseases. This review provides an update on the pathogenesis and therapy for neuronal disorders and will be mainly focused on the recent progress made towards the neuroprotective properties of chitosan and acetylated chitosan oligosaccharides. Their structural features and the underlying molecular mechanisms will also be discussed.

Vanillic acid attenuates Aβ1-42-induced oxidative stress and cognitive impairment in mice

Increasing evidence demonstrates that β-amyloid (Aβ) elicits oxidative stress, which contributes to the pathogenesis and disease progression of Alzheimer’s disease (AD). The aims of the present study were to determine and explore the antioxidant nature and potential mechanism of vanillic acid (VA) in Aβ_1-42-induced oxidative stress and neuroinflammation mediated cognitive impairment in mice. An intracerebroventricular (i.c.v.) injection of Aβ_1-42 into the mouse brain triggered increased reactive oxygen species (ROS) levels, neuroinflammation, synaptic deficits, memory impairment, and neurodegeneration. In contrast, the i.p. (intraperitoneal) administration of VA (30 mg/kg, for 3 weeks) after Aβ_1-42-injection enhanced glutathione levels (GSH) and abrogated ROS generation accompanied by an induction of the endogenous nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) via the activation of Akt and glycogen synthase kinase 3β (GSK-3β) in the brain mice. Additionally, VA treatment decreased Aβ_1-42-induced neuronal apoptosis and neuroinflammation and improved synaptic and cognitive deficits. Moreover, VA was nontoxic to HT22 cells and increased cell viability after Aβ_1-42 exposure. To our knowledge, this study is the first to reveal the neuroprotective effect of VA against Aβ_1-42-induced neurotoxicity. Our findings demonstrate that VA could potentially serve as a novel, promising, and accessible neuroprotective agent against progressive neurodegenerative diseases such as AD.

Involvement of Nrf2-mediated heme oxygenase-1 expression in anti-inflammatory action of chitosan oligosaccharides through MAPK activation in murine macrophages

Chitosan and its derivatives have been reported to have anti-inflammatory effects in vitro and in vivo. It is also suggested that chitosan and its derivatives could be up-regulating heme oxygenase-1 (HO-1) in different models. However, the up-regulation of HO-1 by chitosan oligosaccharides (COS) remains unexplored in regard to anti-inflammatory action in lipopolysaccharide (LPS)-stimulated murine macrophages (RAW264.7 cells). Treatment with COS induced HO-1 expression in LPS-stimulated RAW264.7 cells, whereas the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was decreased. Pretreatment with ZnPP, a HO-1 inhibitor, reduced the COS-mediated anti-inflammatory action. HO-1 induction is mediated by activating the nuclear translocation of NF-E2-related factor 2 (Nrf2) using COS. Moreover, COS increased the phosphorylation of extracellular signal regulated kinase (ERK1/2), c-Jun N-terminal kinase/stress-activated protein kinase (JNK), and p38 MAPK. However, specific inhibitors of ERK, JNK, and p38 reduced COS-mediated nuclear translocation of Nrf2. Therefore, HO-1 induction also decreased in RAW264.7 cells. Collectively, COS exert an anti-inflammatory effect through Nrf2/MAPK-mediated HO-1 induction.

Chitosan oligosaccharide: Biological activities and potential therapeutic applications

Chitosan oligosaccharide (COS) is an oligomer of β-(1➔4)-linked d-glucosamine. COS can be prepared from the deacetylation and hydrolysis of chitin, which is commonly found in the exoskeletons of arthropods and insects and the cell walls of fungi. COS is water soluble, non-cytotoxic, readily absorbed through the intestine and mainly excreted in the urine. Of particular importance, COS and its derivatives have been demonstrated to possess several biological activities including anti-inflammation, immunostimulation, anti-tumor, anti-obesity, anti-hypertension, anti-Alzheimer's disease, tissue regeneration promotion, drug and DNA delivery enhancement, anti-microbial, anti-oxidation and calcium-absorption enhancement. The mechanisms of actions of COS have been found to involve the modulation of several important pathways including the suppression of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) and the activation of AMP-activated protein kinase (AMPK). This review summarizes the current knowledge of the preparation methods, pharmacokinetic profiles, biological activities, potential therapeutic applications and safety profiles of COS and its derivatives. In addition, future research directions are discussed.

Nanoceria restrains PM2.5-induced metabolic disorder and hypothalamus inflammation by inhibition of astrocytes activation related NF-κB pathway in Nrf2 deficient mice

Increasing studies demonstrated that air pollution (PM2.5) plays a significant role in metabolic and neurological diseases. Unfortunately, there is no direct testimony of this, and yet the molecular mechanism by which the occurrence remains unclear. In this regard, we investigated the role of NF-κB and Nrf2 signaling in PM2.5-induced metabolic disorders and neuroinflammation, and further confirmed whether Nrf2 deficiency promoted PM2.5-induced inflammatory response by up regulating astrocytes activation and nerve injury via modulating NF-κB signaling pathways. Present results found that, indeed, PM2.5 challenges results in glucose tolerance, insulin resistance, dysarteriotony, peripheral inflammation, nerve injury and hypothalamus oxidative stress through astrocytes activation related NF-κB pathway in Nrf2 deficient mice. Moreover, in vitro study, we confirmed that activated astrocytes induced by PM2.5 were involved in pathogenesis of hypothalamic inflammation, which were significantly associated with NF-κB signaling. Nanoceria as potential anti-inflammatory and anti-oxidant stress biomaterial has gained increasing attention. Moderate nanoceria treatment is able to restrain PM2.5-induced metabolic syndrome and inflammation. Inhibition of astrocytes activation related NF-κB and enhancement of Nrf2 by cerium oxide were observed in vivo and in vitro, suggesting cerium oxide inhibited hypothalamic inflammation and nerve injury by altering hypothalamic neuroendocrine alterations and decreasing glial cells activation. In addition, NF-κB inhibitor pyrollidine dithiocarbamate (PDTC) treated primary astrocytes directly determined Nrf2 pathway could be up regulated by dose-dependent nanoceria. These results suggest a new therapeutic approach or target to protect against air pollution related diseases by cerium oxide treatment.

Chitosan attenuates dibutyltin-induced apoptosis in PC12 cells through inhibition of the mitochondria-dependent pathway

Dibutyltin (DBT) which was widely used as biocide and plastic stabilizer has been described as a potent neurotoxicant. Chitosan (CS), a natural nontoxic biopolymer, possesses a variety of biological activities including antibacterial, antifungal, free radical scavenging and neuroprotective activities. The present study was undertaken to investigate the protective effects of CS against DBT-induced apoptosis in rat pheochromocytoma (PC12) cells and the underlying mechanisms in vitro. Our results demonstrated that pretreatment with CS significantly increased the cell viability and decreased lactate dehydrogenase (LDH) release induced by DBT in a dose-dependent manner. Meanwhile, DBT-induced cell apoptosis, mitochondrial membrane potential (MMP) disruption, and generation of intracellular reactive oxygen species (ROS) were attenuated by CS. Real-time PCR assay showed that DBT markedly enhanced the mRNA levels of Bax, Bad, cytochrome-c and Apaf-1, reduced the Bcl-2 and Bcl-xL mRNA levels, while these genes expression alteration could be partially reversed by CS treatment. Furthermore, CS also inhibited the DBT-inducted activation of caspase-9, and -3 at mRNA and protein expression levels. Taken together, these results suggested that CS could protect the PC12 cells from apoptosis induced by DBT through inhibition of the mitochondria-dependent pathway.