Intranasal deferoxamine improves performance in radial arm water maze, stabilizes HIF-1α, and phosphorylates GSK3β in P301L tau transgenic mice

HIF-1α serves as a co-linker between AD and T2DM

Alzheimer's disease (AD)-related brain deterioration is linked to the type 2 diabetes mellitus (T2DM) features hyperglycemia, hyperinsulinemia, and insulin resistance. Hypoxia as a common risk factor for both AD and T2DM. Hypoxia-inducible factor-1 alpha (HIF-1α) acts as the main regulator of the hypoxia response and may be a key target in the comorbidity of AD and T2DM. HIF-1α expression is closely related to hyperglycemia, insulin resistance, and inflammation. Tissue oxygen consumption disrupts HIF-1α homeostasis, leading to increased reactive oxygen species levels and the inhibition of insulin receptor pathway activity, causing neuroinflammation, insulin resistance, abnormal Aβ deposition, and tau hyperphosphorylation. HIF-1α activation also leads to the deposition of Aβ by promoting the abnormal shearing of amyloid precursor protein and inhibiting the degradation of Aβ, and it promotes tau hyperphosphorylation by activating oxidative stress and the activation of astrocytes, which further exasperates AD. Therefore, we believe that HIF-α has great potential as a target for the treatment of AD. Importantly, the intracellular homeostasis of HIF-1α is a more crucial factor than its expression level.

Molecular mechanism and potential therapeutic targets of necroptosis and ferroptosis in Alzheimer's disease

Alzheimer's disease (AD), a neurodegenerative condition, is defined by neurofibrillary tangles, amyloid plaques, and gradual cognitive decline. Regardless of the advances in understanding AD's pathogenesis and progression, its causes are still contested, and there are currently no efficient therapies for the illness. The post-mortem analyses revealed widespread neuronal loss in multiple brain regions in AD, evidenced by a decrease in neuronal density and correlated with the disease's progression and cognitive deterioration. AD's neurodegeneration is complicated, and different types of neuronal cell death, alone or in combination, play crucial roles in this process. Recently, the involvement of non-apoptotic programmed cell death in the neurodegenerative mechanisms of AD has received a lot of attention. Aberrant activation of necroptosis and ferroptosis, two newly discovered forms of regulated non-apoptotic cell death, is thought to contribute to neuronal cell death in AD. In this review, we first address the main features of necroptosis and ferroptosis, cellular signaling cascades, and the mechanisms involved in AD pathology. Then, we discuss the latest therapies targeting necroptosis and ferroptosis in AD animal/cell models and human research to provide vital information for AD treatment.

Berberine ameliorates iron levels and ferroptosis in the brain of 3 × Tg-AD mice

BACKGROUND

Berberine (BBR) is a natural alkaloid extracted from the herb Coptis chinensis. This compound has the ability to penetrate the blood-brain barrier (BBB) and exhibit neuroprotective value in the treatment of Alzheimer's disease (AD). AD is a neurodegenerative disease characterized by β-amyloid (Aβ) deposition, hyperphosphorylated tau and other characters. Iron accumulation and ferroptosis were also detected in AD brain, which can result in neuronal damage. However, it is still unclear whether BBR can suppress ferroptosis in AD and alleviate its underlying pathology.

PURPOSE

This study investigated whether BBR may affect ferroptosis and related signaling pathways in triple transgenic AD (3 × Tg-AD) mice.

METHODS

Four-month-old 3 × Tg-AD mice received oral administration of BBR at a dose of 50 mg/kg for 7.5 months. Cognitive function and anxiety levels in mice were assessed using the morris water maze test, open field test, and novel object recognition test. Western blot, immunohistochemistry, and ICP-MS were employed to assess the pathology of AD, brain iron metabolism, and ferroptosis signaling pathways. Transmission electron microscopy was used to detect mitochondrial changes. The synergistic effects of BBR combined with Nrf2 were investigated using molecular docking programs and surface plasmon resonance technology. Co-inmunoprecipitation assay was used to examine the effect of BBR on the binding ability of Nrf2 and Keap1.

RESULTS

The results indicated that chronic treatment of BBR mitigated cognitive disorders in 3 × Tg-AD model mice. Reductions in Aβ plaque, hyperphosphorylated tau protein, neuronal loss, and ferroptosis in the brains of 3 × Tg-AD mice suggested that BBR could alleviate brain injury. In addition, BBR treatment attenuated ferroptosis, as evidenced by decreased levels of iron, MDA, and ROS, while enhancing SOD, GSH, GPX4, and SLC7A11. Consistent with the in vivo assay, BBR inhibited RSL3-induced ferroptosis in N2a-sw cells. BBR increased the expression levels of GPX4, FPN1 and SLC7A11 by regulating Nrf2 transcription levels, thereby inhibiting ferroptosis. Molecular docking programs and surface plasmon resonance technology demonstrated the direct combination of BBR with Nrf2. Co-inmunoprecipitation analysis showed that BBR inhibited the interaction between Keap1 and Nrf2.

CONCLUSION

For the first time, these results showed that BBR could inhibit iron levels and ferroptosis in the brains of 3 × Tg-AD model mice and partially protect against RSL3-induced ferroptosis via the activation of Nrf2 signaling.

Molecular and neural roles of sodium-glucose cotransporter 2 inhibitors in alleviating neurocognitive impairment in diabetic mice

Diabetes causes a variety of molecular changes in the brain, making it a real risk factor for the development of cognitive dysfunction. Complex pathogenesis and clinical heterogeneity of cognitive impairment makes the efficacy of current drugs limited. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) gained our attention as drugs with potential beneficial effects on the CNS. In the present study, these drugs ameliorated the cognitive impairment associated with diabetes. Moreover, we verified whether SGLT2i can mediate the degradation of amyloid precursor protein (APP) and modulation of gene expression (Bdnf, Snca, App) involved in the control of neuronal proliferation and memory. The results of our research proved the participation of SGLT2i in the multifactorial process of neuroprotection. SGLT2i attenuate the neurocognitive impairment through the restoration of neurotrophin levels, modulation of neuroinflammatory signaling, and gene expression of Snca, Bdnf, and App in the brain of diabetic mice. The targeting of the above-mentioned genes is currently seen as one of the most promising and developed therapeutic strategies for diseases associated with cognitive dysfunction. The results of this work could form the basis of a future administration of SGLT2i in diabetics with neurocognitive impairment.

Challenges and Opportunities of Metal Chelation Therapy in Trace Metals Overload-Induced Alzheimer's Disease

Essential trace metals like zinc (Zn), iron (Fe), and copper (Cu) play an important physiological role in the metabolomics and healthy functioning of body organs, including the brain. However, abnormal accumulation of trace metals in the brain and dyshomeostasis in the different regions of the brain have emerged as contributing factors in neuronal degeneration, Aβ aggregation, and Tau formation. The link between these essential trace metal ions and the risk of AD has been widely studied, although the conclusions have been ambiguous. Despite the absence of evidence for any clinical benefit, therapeutic chelation is still hypothesized to be a therapeutic option for AD. Furthermore, the parameters like bioavailability, ability to cross the BBB, and chelation specificity must be taken into consideration while selecting a suitable chelation therapy. The data in this review summarizes that the primary intervention in AD is brain metal homeostasis along with brain metal scavenging. This review evaluates the impact of different trace metals (Cu, Zn, Fe) on normal brain functioning and their association with neurodegeneration in AD. Also, it investigates the therapeutic potential of metal chelators in the management of AD. An extensive literature search was carried out on the "Web of Science, PubMed, Science Direct, and Google Scholar" to investigate the effect of trace elements in neurological impairment and the role of metal chelators in AD. In addition, the current review highlights the advantages and limitations of chelation therapies and the difficulties involved in developing selective metal chelation therapy in AD patients.

APP Knock-In Mice Produce E22P-Aβ Exhibiting an Alzheimer's Disease-like Phenotype with Dysregulation of Hypoxia-Inducible Factor Expression

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that requires further pathological elucidation to establish effective treatment strategies. We previously showed that amyloid β (Aβ) toxic conformer with a turn at positions 22-23 is essential for forming highly toxic oligomers. In the present study, we evaluated phenotypic changes with aging in AD model AppNL-P-F/NL-P-F (NL-P-F) mice with Swedish mutation (NL), Iberian mutation (F), and mutation (P) overproducing E22P-Aβ, a mimic of toxic conformer utilizing the knock-in technique. Furthermore, the role of the toxic conformer in AD pathology was investigated. NL-P-F mice produced soluble toxic conformers from an early age. They showed impaired synaptic plasticity, glial cell activation, and cognitive decline, followed by the accumulation of Aβ plaques and tau hyperphosphorylation. In addition, the protein expression of hypoxia-inducible factor (HIF)-1α was increased, and gene expression of HIF-3α was decreased in NL-P-F mice. HIF dysregulation due to the production of soluble toxic conformers may be involved in AD pathology in NL-P-F mice. This study could reveal the role of a highly toxic Aβ on AD pathogenesis, thereby contributing to the development of a novel therapeutic strategy targeting the toxic conformer.

Iron Dyshomeostasis and Ferroptosis: A New Alzheimer’s Disease Hypothesis?

Iron plays a crucial role in many physiological processes of the human body, but iron is continuously deposited in the brain as we age. Early studies found iron overload is directly proportional to cognitive decline in Alzheimer’s disease (AD). Amyloid precursor protein (APP) and tau protein, both of which are related to the AD pathogenesis, are associated with brain iron metabolism. A variety of iron metabolism-related proteins have been found to be abnormally expressed in the brains of AD patients and mouse models, resulting in iron deposition and promoting AD progression. Amyloid β (Aβ) and hyperphosphorylated tau, two pathological hallmarks of AD, can also promote iron deposition in the brain, forming a vicious cycle of AD development-iron deposition. Iron deposition and the subsequent ferroptosis has been found to be a potential mechanism underlying neuronal loss in many neurodegenerative diseases. Iron chelators, antioxidants and hepcidin were found useful for treating AD, which represents an important direction for AD treatment research and drug development in the future. The review explored the deep connection between iron dysregulation and AD pathogenesis, discussed the potential of new hypothesis related to iron dyshomeostasis and ferroptosis, and summarized the therapeutics capable of targeting iron, with the expectation to draw more attention of iron dysregulation and corresponding drug development.

Intranasal neprilysin rapidly eliminates amyloid-beta plaques, but causes plaque compensations: the explanation why the amyloid-beta cascade may fail?

Neurodegenerative brain disorders are a major burden in our society, such as Alzheimer´s disease. In order to repair or prevent such diseases, drugs are designed which enter the brain, but the blood-brain barrier limits their entry and the search for alternative pathways is important. Recently, we reported that intranasal delivery of the amyloid-beta degrading enzyme neprilysin eliminated amyloid-beta plaques in transgenic Alzheimer´s disease mice. This review describes the anatomical structure of the intranasal pathway, explains the intranasal delivery of pure neprilysin, cell-loaded neprilysin (platelets) and collagen-embedded neprilysin to destruct amyloid-beta plaques in Alzheimer´s disease in transgenic APP_SweDI mice and hypothesizes why this may cause compensation and why the amyloid-beta cascade hypothesis may fail.

The Potential of Ferroptosis-Targeting Therapies for Alzheimer's Disease: From Mechanism to Transcriptomic Analysis

Alzheimer’s disease (AD), the most common form of dementia, currently affects 40–50 million people worldwide. Despite the extensive research into amyloid β (Aβ) deposition and tau protein hyperphosphorylation (p-tau), an effective treatment to stop or slow down the progression of neurodegeneration is missing. Emerging evidence suggests that ferroptosis, an iron-dependent and lipid peroxidation-driven type of programmed cell death, contributes to neurodegeneration in AD. Therefore, how to intervene against ferroptosis in the context of AD has become one of the questions addressed by studies aiming to develop novel therapeutic strategies. However, the underlying molecular mechanism of ferroptosis in AD, when ferroptosis occurs in the disease course, and which ferroptosis-related genes are differentially expressed in AD remains to be established. In this review, we summarize the current knowledge on cell mechanisms involved in ferroptosis, we discuss how these processes relate to AD, and we analyze which ferroptosis-related genes are differentially expressed in AD brain dependant on cell type, disease progression and gender. In addition, we point out the existing targets for therapeutic options to prevent ferroptosis in AD. Future studies should focus on developing new tools able to demonstrate where and when cells undergo ferroptosis in AD brain and build more translatable AD models for identifying anti-ferroptotic agents able to slow down neurodegeneration.

Novel Targets and Interventions for Cognitive Complications of Diabetes

Diabetes and cognitive dysfunction, ranging from mild cognitive impairment to dementia, often coexist in individuals over 65 years of age. Vascular contributions to cognitive impairment/dementia (VCID) are the second leading cause of dementias under the umbrella of Alzheimer's disease and related dementias (ADRD). Over half of dementia patients have VCID either as a single pathology or a mixed dementia with AD. While the prevalence of type 2 diabetes in individuals with dementia can be as high as 39% and diabetes increases the risk of cerebrovascular disease and stroke, VCID remains to be one of the less understood and less studied complications of diabetes. We have identified cerebrovascular dysfunction and compromised endothelial integrity leading to decreased cerebral blood flow and iron deposition into the brain, respectively, as targets for intervention for the prevention of VCID in diabetes. This review will focus on targeted therapies that improve endothelial function or remove iron without systemic effects, such as agents delivered intranasally, that may result in actionable and disease-modifying novel treatments in the high-risk diabetic population.

Oxygen Sensing and Signaling in Alzheimer's Disease: A Breathtaking Story!

Oxygen sensing and homeostasis is indispensable for the maintenance of brain structural and functional integrity. Under low-oxygen tension, the non-diseased brain has the ability to cope with hypoxia by triggering a homeostatic response governed by the highly conserved hypoxia-inducible family (HIF) of transcription factors. With the advent of advanced neuroimaging tools, it is now recognized that cerebral hypoperfusion, and consequently hypoxia, is a consistent feature along the Alzheimer's disease (AD) continuum. Of note, the reduction in cerebral blood flow and tissue oxygenation detected during the prodromal phases of AD, drastically aggravates as disease progresses. Within this scenario a fundamental question arises: How HIF-driven homeostatic brain response to hypoxia "behaves" during the AD continuum? In this sense, the present review is aimed to critically discuss and summarize the current knowledge regarding the involvement of hypoxia and HIF signaling in the onset and progression of AD pathology. Importantly, the promises and challenges of non-pharmacological and pharmacological strategies aimed to target hypoxia will be discussed as a new "hope" to prevent and/or postpone the neurodegenerative events that occur in the AD brain.

Intranasal Delivery of Collagen-Loaded Neprilysin Clears Beta-Amyloid Plaques in a Transgenic Alzheimer Mouse Model

Alzheimer’s disease (AD) is pathologically characterized by extracellular beta-amyloid (Aβ) plaques and intraneuronal tau tangles in the brain. A therapeutic strategy aims to prevent or clear these Aβ plaques and the Aβ-degrading enzyme neprilysin is a potent drug to degrade plaques. The major challenge is to deliver bioactive neprilysin into the brain via the blood-brain barrier. The aim of the present study is to explore if intranasal delivery of neprilysin can eliminate plaques in a transgenic AD mouse model (APP_SweDI). We will test if collagen or platelets are useful vehicles to deliver neprilysin into the brain. Using organotypic brain slices from adult transgenic APP_SweDI mice, we show that neprilysin alone or loaded in collagen hydrogels or in platelets cleared cortical plaques. Intransasal delivery of neprilysin alone increased small Aβ depositions in the middle and caudal cortex in transgenic mice. Platelets loaded with neprilysin cleared plaques in the frontal cortex after intranasal application. Intranasal delivery of collagen-loaded neprilysin was very potent to clear plaques especially in the middle and caudal parts of the cortex. Our data support that the Aβ degrading enzyme neprilysin delivered to the mouse brain can clear Aβ plaques and intranasal delivery (especially with collagen as a vehicle) is a fast and easy application. However, it must be considered that intranasal neprilysin may also activate more plaque production in the transgenic mouse brain as a side effect.

Deferiprone Treatment in Aged Transgenic Tau Mice Improves Y-Maze Performance and Alters Tau Pathology

The accumulation of neurofibrillary tangles (NFTs), which is composed of abnormally hyperphosphorylated tau aggregates, is the classic neuropathology associated with cognitive dysfunction in tauopathies such as Alzheimer's disease (AD). However, there is an emerging theory suggesting that dysregulation in cerebral iron may contribute to NFT formation. Iron is speculated to bind to tau and induce conformational changes of the protein, potentially leading to subsequent aggregation and cognitive decline. Deferiprone (DFP) is a clinically available iron chelator, which has demonstrated potential therapeutic advantages of chelating iron in neurodegenerative disorders, and is currently in clinical trials for AD. However, its effect on tau pathology remains unclear. Here, we report the effects of short-term DFP treatment (4 weeks, 100 mg/kg/daily, via oral gavage) in a mixed-gender cohort of the rTg(tauP301L)4510 mouse model of tauopathy. Our results revealed that DFP improved Y-maze and open field performance, accompanied by a 28% decrease in brain iron levels, measured by inductively coupled plasma mass spectrometry (ICP-MS) and reduced AT8-labeled p-tau within the hippocampus in transgenic tau mice. This data supports the notion that iron may play a neurotoxic role in tauopathies and may be a potential therapeutic target for this class of disorders that can be modulated by the clinically available metal chelator DFP.

Mechanisms of Intranasal Deferoxamine in Neurodegenerative and Neurovascular Disease

Identifying disease-modifying therapies for neurological diseases remains one of the greatest gaps in modern medicine. Herein, we present the rationale for intranasal (IN) delivery of deferoxamine (DFO), a high-affinity iron chelator, as a treatment for neurodegenerative and neurovascular disease with a focus on its novel mechanisms. Brain iron dyshomeostasis with iron accumulation is a known feature of brain aging and is implicated in the pathogenesis of a number of neurological diseases. A substantial body of preclinical evidence and early clinical data has demonstrated that IN DFO and other iron chelators have strong disease-modifying impacts in Alzheimer’s disease (AD), Parkinson’s disease (PD), ischemic stroke, and intracranial hemorrhage (ICH). Acting by the disease-nonspecific pathway of iron chelation, DFO targets each of these complex diseases via multifactorial mechanisms. Accumulating lines of evidence suggest further mechanisms by which IN DFO may also be beneficial in cognitive aging, multiple sclerosis, traumatic brain injury, other neurodegenerative diseases, and vascular dementia. Considering its known safety profile, targeted delivery method, robust preclinical efficacy, multiple mechanisms, and potential applicability across many neurological diseases, the case for further development of IN DFO is considerable.

The essential elements of Alzheimer's disease

Treatments for Alzheimer’s disease (AD) directed against the prominent amyloid plaque neuropathology are yet to be proved effective despite many phase 3 clinical trials. There are several other neurochemical abnormalities that occur in the AD brain that warrant renewed emphasis as potential therapeutic targets for this disease. Among those are the elementomic signatures of iron, copper, zinc, and selenium. Here, we review these essential elements of AD for their broad potential to contribute to Alzheimer’s pathophysiology, and we also highlight more recent attempts to translate these findings into therapeutics. A reinspection of large bodies of discovery in the AD field, such as this, may inspire new thinking about pathogenesis and therapeutic targets.

Challenges and Opportunities of Deferoxamine Delivery for Treatment of Alzheimer's Disease, Parkinson's Disease, and Intracerebral Hemorrhage

Deferoxamine mesylate (DFO) is an FDA-approved, hexadentate iron chelator routinely used to alleviate systemic iron burden in thalassemia major and sickle cell patients. Iron accumulation in these disease states results from the repeated blood transfusions required to manage these conditions. Iron accumulation has also been implicated in the pathogenesis of Alzheimer's disease (AD), Parkinson's disease (PD), and secondary injury following intracerebral hemorrhage (ICH). Chelation of brain iron is thus a promising therapeutic strategy for improving behavioral outcomes and slowing neurodegeneration in the aforementioned disease states, though the effectiveness of DFO treatment is limited on several accounts. Systemically administered DFO results in nonspecific toxicity at high doses, and the drug's short half-life leads to low patient compliance. Mixed reports of DFO's ability to cross the blood-brain barrier (BBB) also appear in literature. These limitations necessitate novel DFO formulations prior to the drug's widespread use in managing neurodegeneration. Herein, we discuss the various dosing regimens and formulations employed in intranasal (IN) or systemic DFO treatment, as well as the physiological and behavioral outcomes observed in animal models of AD, PD, and ICH. The clinical progress of chelation therapy with DFO in managing neurodegeneration is also evaluated. Finally, the elimination of intranasally administered particles via the glymphatic system and efflux transporters is discussed. Abundant preclinical evidence suggests that intranasal DFO treatment improves memory retention and behavioral outcome in rodent models of AD, PD, and ICH. Several other biochemical and physiological metrics, such as tau phosphorylation, the survival of tyrosine hydroxylase-positive neurons, and infarct volume, are also positively affected by intranasal DFO treatment. However, dosing regimens are inconsistent across studies, and little is known about brain DFO concentration following treatment. Systemic DFO treatment yields similar results, and some complex formulations have been developed to improve permeability across the BBB. However, despite the success in preclinical models, clinical translation is limited with most clinical evidence investigating DFO treatment in ICH patients, where high-dose treatment has proven dangerous and dosing regimens are not consistent across studies. DFO is a strong drug candidate for managing neurodegeneration in the aging population, but before it can be routinely implemented as a therapeutic agent, dosing regimens must be standardized, and brain DFO content following drug administration must be understood and controlled via novel formulations.

Overdosing on iron: Elevated iron and degenerative brain disorders

IMPACT STATEMENT

Brain degenerative disorders, which include some neurodevelopmental disorders and age-associated diseases, cause debilitating neurological deficits and are generally fatal. A large body of emerging evidence indicates that iron accumulation in neurons within specific regions of the brain plays an important role in the pathogenesis of many of these disorders. Iron homeostasis is a highly complex and incompletely understood process involving a large number of regulatory molecules. Our review provides a description of what is known about how iron is obtained by the body and brain and how defects in the homeostatic processes could contribute to the development of brain diseases, focusing on Alzheimer's disease and Parkinson's disease as well as four other disorders belonging to a class of inherited conditions referred to as neurodegeneration based on iron accumulation (NBIA) disorders. A description of potential therapeutic approaches being tested for each of these different disorders is provided.

Spotlight on Ferroptosis: Iron-Dependent Cell Death in Alzheimer's Disease

Alzheimer's disease is an emerging global epidemic that is becoming increasingly unsustainable. Most of the clinical trials have been centered around targeting β-amyloid and have met with limited success. There is a great impetus to identify alternative drug targets. Iron appears to be the common theme prevalent across neurodegenerative diseases. Iron has been shown to promote aggregation and pathogenicity of the characteristic aberrant proteins, β-amyloid, tau, α-synuclein, and TDP43, in these diseases. Further support for the involvement of iron in pathogenesis is provided by the recent discovery of a new form of cell death, ferroptosis. Arising from iron-dependent lipid peroxidation, ferroptosis is augmented in conditions of cysteine deficiency and glutathione peroxidase-4 inactivation. Here, we review clinical trials that provide the rationale for targeting ferroptosis to delay the pathogenesis of Alzheimer's disease (AD), potentially of relevance to other neurodegenerative diseases.

The roles of iron and HFE genotype in neurological diseases

Iron accumulation is a recurring pathological phenomenon in many neurological diseases including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, and others. Iron is essential for normal development and functions of the brain; however, excess redox-active iron can also lead to oxidative damage and cell death. Especially for terminally differentiated cells like neurons, regulation of reactive oxygen species is critical for cell viability. As a result, cellular iron level is tightly regulated. Although iron accumulation related to neurological diseases has been well documented, the pathoetiological contributions of the homeostatic iron regulator (HFE), which controls cellular iron uptake, is less understood. Furthermore, a common HFE variant, H63D HFE, has been identified as a modifier of multiple neurological diseases. This review will discuss the roles of iron and HFE in the brain as well as their impact on various disease processes.

Cow's milk protein β-lactoglobulin confers resilience against allergy by targeting complexed iron into immune cells

BACKGROUND

Beta-lactoglobulin (BLG) is a bovine lipocalin in milk with an innate defense function. The circumstances under which BLG is associated with tolerance of or allergy to milk are not understood.

OBJECTIVE

Our aims were to assess the capacity of ligand-free apoBLG versus loaded BLG (holoBLG) to protect mice against allergy by using an iron-quercetin complex as an exemplary ligand and to study the molecular mechanisms of this protection.

METHODS

Binding of iron-quercetin to BLG was modeled and confirmed by spectroscopy and docking calculations. Serum IgE binding to apoBLG and holoBLG in children allergic to milk and children tolerant of milk was assessed. Mice were intranasally treated with apoBLG versus holoBLG and analyzed immunologically after systemic challenge. Aryl hydrocarbon receptor (AhR) activation was evaluated with reporter cells and Cyp1A1 expression. Treated human PBMCs and human mast cells were assessed by fluorescence-activated cell sorting and degranulation, respectively.

RESULTS

Modeling predicted masking of major IgE and T-cell epitopes of BLG by ligand binding. In line with this modeling, IgE binding in children allergic to milk was reduced toward holoBLG, which also impaired degranulation of mast cells. In mice, only treatments with holoBLG prevented allergic sensitization and anaphylaxis, while sustaining regulatory T cells. BLG facilitated quercetin-dependent AhR activation and, downstream of AhR, lung Cyp1A1 expression. HoloBLG shuttled iron into monocytic cells and impaired their antigen presentation.

CONCLUSION

The cargo of holoBLG is decisive in preventing allergy in vivo. BLG without cargo acted as an allergen in vivo and further primed human mast cells for degranulation in an antigen-independent fashion. Our data provide a mechanistic explanation why the same proteins can act either as tolerogens or as allergens.

Intranasal deferoxamine can improve memory in healthy C57 mice, suggesting a partially non-disease-specific pathway of functional neurologic improvement

INTRODUCTION

Intranasal deferoxamine (IN DFO) has been shown to decrease memory loss and have beneficial impacts across several models of neurologic disease and injury, including rodent models of Alzheimer's and Parkinson's disease.

METHODS

In order to assess the mechanism of DFO, determine its ability to improve memory from baseline in the absence of a diseased state, and assess targeting ability of intranasal delivery, we treated healthy mice with IN DFO (2.4 mg) or intraperitoneal (IP) DFO and compared behavioral and biochemical changes with saline-treated controls. Mice were treated 5 days/week for 4 weeks and subjected to behavioral tests 30 min after dosing.

RESULTS

We found that IN DFO, but not IP DFO, significantly enhanced working memory in the radial arm water maze, suggesting that IN administration is more efficacious as a targeted delivery route to the brain. Moreover, the ability of DFO to improve memory from baseline in healthy mice suggests a non-disease-specific mechanism of memory improvement. IN DFO treatment was accompanied by decreased GSK-3β activity and increased HIF-1α activity.

CONCLUSIONS

These pathways are suspected in DFO's ability to improve memory and perhaps represent a component of the common mechanism through which DFO enacts beneficial change in models of neurologic disease and injury.

The Iron Chelator Deferiprone Improves the Phenotype in a Mouse Model of Tauopathy

BACKGROUND

Abnormally hyperphosphorylated tau is a defining pathological feature of tauopathies, such as Alzheimer's disease (AD), and accumulating evidence suggests a role for iron in mediating tau pathology that may lead to cognitive decline in these conditions. The metal chelator deferiprone (DFP), which has a high affinity for iron, is currently in clinical trials for AD and Parkinson's disease. However, the effect of DFP on tau pathology remains underexplored.

OBJECTIVE

We aimed to investigate the impact of chronic DFP treatment on tau pathology using a well-characterized mouse model of tauopathy (rTg(tauP301L)4510).

METHODS

Animals were treated daily with DFP (100 mg/kg) via oral gavage for 16 weeks. After 14 weeks, mice were tested in the Y-maze, open field, Morris water maze, and rotorod. At the end of the study, brain tissue was collected to examine metal levels (using inductively coupled plasma-mass spectrometry) and for western blot analysis of DFP on tau and iron associated pathways.

RESULTS

DFP significantly reduced anxiety-like behavior, and revealed a trend toward improved cognitive function. This was accompanied by a decrease in brain iron levels and sarkosyl-insoluble tau. Our data also showed downregulation of the tau kinases glycogen synthase kinase 3β and cyclin dependent kinase-5 in DFP treated mice and an increase in the methylation of the catalytic subunit of protein phosphatase 2A.

CONCLUSION

These data support the hypothesis that suggests that iron plays a neurotoxic role in tauopathies and may be a potential therapeutic target for this class of disorders.

Intranasal Insulin: a Treatment Strategy for Addiction

Addiction to substances such as alcohol, cocaine, opioids, and methamphetamine poses a continuing clinical and public challenge globally. Despite progress in understanding substance use disorders, challenges remain in their treatment. Some of these challenges include limited ability of therapeutics to reach the brain (blood-brain barrier), adverse systemic side effects of current medications, and importantly key aspects of addiction not addressed by currently available treatments (such as cognitive impairment). Inability to sustain abstinence or seek treatment due to cognitive deficits such as poor decision-making and impulsivity is known to cause poor treatment outcomes. In this review, we provide an evidenced-based rationale for intranasal drug delivery as a viable and safe treatment modality to bypass the blood-brain barrier and target insulin to the brain to improve the treatment of addiction. Intranasal insulin with improvement of brain cell energy and glucose metabolism, stress hormone reduction, and improved monoamine transmission may be an ideal approach for treating multiple domains of addiction including memory and impulsivity. This may provide additional benefits to enhance current treatment approaches.

Quantifying Intranasally Administered Deferoxamine in Rat Brain Tissue with Mass Spectrometry

Deferoxamine, a metal chelator, has been shown to be neuroprotective in animal models of ischemic stroke, traumatic brain injury and both subarachnoid and intracerebral hemorrhage. Intranasal deferoxamine (IN DFO) has also shown promise as a potential treatment for multiple neurodegenerative diseases, including Parkinson's and Alzheimer's. However, there have been no attempts to thoroughly understand the dynamics and pharmacokinetics of IN DFO. We developed a new high-performance liquid-chromatography electrospray-tandem mass spectrometry (HPLC/ESI-MS²) method to quantify the combined total levels of DFO, ferrioxamine (FO; DFO bound to iron), and aluminoxamine (AO; aluminum-bound DFO) in brain tissue using a custom-synthesized deuterated analogue (DFO-d₇, Medical Isotopes Inc., Pelham NH) as an internal standard. We applied our method toward understanding the pharmacokinetics of IN DFO delivery to the brain and blood of rats from 15 min to 4 h after delivery. We found that IN delivery successfully targets DFO to the brain to achieve concentrations of 0.5-15 μM in various brain regions within 15 min, and decreasing though still detectable after 4 h. Systemic exposure was minimized as assessed by concentration in blood serum. Serum concentrations were 0.02 μM at 15 min and no more than 0.1 μM at later time points. Compared to blood serum, brain region-specific drug exposure (as measured by area under the curve) ranged from slightly under 10 times exposure in the hippocampus to almost 200 times exposure in the olfactory bulb with IN DFO delivery. These findings represent a major step toward future method development, pharmacokinetic studies, and clinical trials for this promising therapeutic.

Ferroptosis Contributes to Isoflurane Neurotoxicity

The underlying mechanisms of isoflurane neurotoxicity in the developing brain remain unclear. Ferroptosis is a recently characterized form of programmed cell death distinct from apoptosis or autophagy, characterized by iron-dependent reactive oxygen species (ROS) generation secondary to failure of glutathione-dependent antioxidant defenses. The results of the present study are the first to demonstrate in vitro that ferroptosis is a central mechanism contributing to isoflurane neurotoxicity. We observed in embryonic mouse primary cortical neuronal cultures (day-in-vitro 7) that 6 h of 2% isoflurane exposure was associated with decreased transcription and protein expression of the lipid repair enzyme glutathione peroxidase 4. In parallel, isoflurane exposure resulted in increased ROS generation, disruption in mitochondrial membrane potential, and cell death. These effects were significantly attenuated by pre-treatment with the selective ferroptosis inhibitor ferrostatin-1 (Fer-1). Collectively, these observations provide a novel mechanism for isoflurane-induced injury in the developing brain and suggest that pre-treatment with Fer-1 may be a potential clinical intervention for neuroprotection.

Diagnostics and Treatments of Iron-Related CNS Diseases

Iron has been proposed to be responsible for neuronal loss in several diseases of the central nervous system, including Alzheimer's disease (AD), Parkinson's disease (PD), stroke, Friedreich's ataxia (FRDA), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS). In many diseases, abnormal accumulation of brain iron in disease-affected area has been observed, without clear knowledge of the contribution of iron overload to pathogenesis. Recent evidences implicate that key proteins involved in the disease pathogenesis may also participate in cellular iron metabolism, suggesting that the imbalance of brain iron homeostasis is associated with the diseases. Considering the complicated regulation of iron homeostasis within the brain, a thorough understanding of the molecular events leading to this phenotype is still to be investigated. However, current understanding has already provided the basis for the diagnosis and treatment of iron-related CNS diseases, which will be reviewed here.

Iron and Alzheimer's Disease: From Pathogenesis to Therapeutic Implications

As people age, iron deposits in different areas of the brain may impair normal cognitive function and behavior. Abnormal iron metabolism generates hydroxyl radicals through the Fenton reaction, triggers oxidative stress reactions, damages cell lipids, protein and DNA structure and function, and ultimately leads to cell death. There is an imbalance in iron homeostasis in Alzheimer's disease (AD). Excessive iron contributes to the deposition of β-amyloid and the formation of neurofibrillary tangles, which in turn, promotes the development of AD. Therefore, iron-targeted therapeutic strategies have become a new direction. Iron chelators, such as desferoxamine, deferiprone, deferasirox, and clioquinol, have received a great deal of attention and have obtained good results in scientific experiments and some clinical trials. Given the limitations and side effects of the long-term application of traditional iron chelators, alpha-lipoic acid and lactoferrin, as self-synthesized naturally small molecules, have shown very intriguing biological activities in blocking Aβ-aggregation, tauopathy and neuronal damage. Despite a lack of evidence for any clinical benefits, the conjecture that therapeutic chelation, with a special focus on iron ions, is a valuable approach for treating AD remains widespread.

Untangling Tau and Iron: Exploring the Interaction Between Iron and Tau in Neurodegeneration

There is an emerging link between the accumulation of iron in the brain and abnormal tau pathology in a number of neurodegenerative disorders, such as Alzheimer’s disease (AD). Studies have demonstrated that iron can regulate tau phosphorylation by inducing the activity of multiple kinases that promote tau hyperphosphorylation and potentially also by impacting protein phosphatase 2A activity. Iron is also reported to induce the aggregation of hyperphosphorylated tau, possibly through a direct interaction via a putative iron binding motif in the tau protein, facilitating the formation of neurofibrillary tangles (NFTs). Furthermore, in human studies high levels of iron have been reported to co-localize with tau in NFT-bearing neurons. These data, together with our own work showing that tau has a role in mediating cellular iron efflux, provide evidence supporting a critical tau:iron interaction that may impact both the symptomatic presentation and the progression of disease. Importantly, this may also have relevance for therapeutic directions, and indeed, the use of iron chelators such as deferiprone and deferoxamine have been reported to alleviate the phenotypes, reduce phosphorylated tau levels and stabilize iron regulation in various animal models. As these compounds are also moving towards clinical translation, then it is imperative that we understand the intersection between iron and tau in neurodegeneration. In this article, we provide an overview of the key pathological and biochemical interactions between tau and iron. We also review the role of iron and tau in disease pathology and the potential of metal-based therapies for tauopathies.

Iron chelator deferiprone rescues memory deficits, hippocampal BDNF levels and antioxidant defenses in an experimental model of memory impairment

Brain-derived neurotrophic factor (BDNF) plays a key role in neural development and physiology, as well as in pathological states. Post-mortem studies demonstrate that BDNF is reduced in the brains of patients affected by neurodegenerative diseases. Iron accumulation has also been associated to the pathogenesis of neurodegenerative diseases. In rats, iron overload induces persistent memory deficits, increases oxidative stress and apoptotic markers, and decreases the expression of the synaptic marker, synaptophysin. Deferiprone (DFP) is an oral iron chelator used for the treatment of systemic iron overload disorders, and has recently been tested for Parkinson's disease. Here, we investigated the effects of iron overload on BDNF levels and on mRNA expression of genes encoding TrkB, p75^NTR, catalase (CAT) and NQO1. We also aimed at investigating the effects of DFP on iron-induced impairments. Rats received iron or vehicle at postnatal days 12-14 and when adults, received chronic DFP or water (vehicle). Recognition memory was tested 19 days after the beginning of chelation therapy. BDNF measurements and expression analyses in the hippocampus were performed 24 h after the last day of DFP treatment. DFP restored memory and increased hippocampal BDNF levels, ameliorating iron-induced effects. Iron overload in the neonatal period reduced, while treatment with DFP was able to rescue, the expression of antioxidant enzymes CAT and NQO1.

Intranasal deferoxamine affects memory loss, oxidation, and the insulin pathway in the streptozotocin rat model of Alzheimer's disease

Accumulation of metal and the accompanying increase in oxidative stress and inflammation plays an important role in neurodegenerative disease. Deferoxamine (DFO) is a metal chelator found to be beneficial in several animal models of neurodegenerative disease and insult including Alzheimer's disease, Parkinson's disease, stroke, and subarachnoid hemorrhage. In this study, we determine whether intranasally (IN) administered DFO is beneficial in the intracerebroventricular streptozotocin (ICV STZ) rat model of sporadic Alzheimer's disease, which is different from previous models in that it exhibits dysregulation of insulin metabolism as well as oxidative stress and inflammation. Surgical induction of the model included ICV injections of either STZ or citrate buffer (sham in rats), which were treated IN with either saline or DFO (n=10-15/group). Treatment started either before or after injection of STZ to induce the model, and continued throughout the study. IN treatment continued three times per week for three weeks before behavior tests started followed by eventual euthanasia with tissue collection. Spatial memory tests with the Morris water maze showed that STZ rats treated with IN DFO both before and after model induction had significantly shorter escape latencies. Pre-treatment with IN DFO also significantly decreased footslips on the tapered balance beam test. Brain tissue analyses showed DFO treatment decreased oxidation as measured by oxyblot and increased insulin receptor expression. These results further support the potential of IN DFO for use as a treatment for Alzheimer's disease, and show benefit in a non-amyloid/tau rodent model.

Insulin Resistance and Neurodegeneration: Progress Towards the Development of New Therapeutics for Alzheimer's Disease

Alzheimer's disease (AD) should be regarded as a degenerative metabolic disease caused by brain insulin resistance and deficiency, and overlapping with the molecular, biochemical, pathophysiological, and metabolic dysfunctions in diabetes mellitus, non-alcoholic fatty liver disease, and metabolic syndrome. Although most of the diagnostic and therapeutic approaches over the past several decades have focused on amyloid-beta (Aβ42) and aberrantly phosphorylated tau, which could be caused by consequences of brain insulin resistance, the broader array of pathologies including white matter atrophy with loss of myelinated fibrils and leukoaraiosis, non-Aβ42 microvascular disease, dysregulated lipid metabolism, mitochondrial dysfunction, astrocytic gliosis, neuro-inflammation, and loss of synapses vis-à-vis growth of dystrophic neurites, is not readily accounted for by Aβ42 accumulations, but could be explained by dysregulated insulin/IGF-1 signaling with attendant impairments in signal transduction and gene expression. This review covers the diverse range of brain abnormalities in AD and discusses how insulins, incretins, and insulin sensitizers could be utilized to treat at different stages of neurodegeneration.

Intranasal Cerebrolysin Attenuates Learning and Memory Impairments in D-galactose-Induced Senescence in Mice

Neurotrophic factors are currently being considered as pro-cognitive therapeutic approaches for management of cognitive deficits. This study aims to evaluate the effects of intranasal (i.n.) or intraperitoneal (i.p.) administration of Cerebrolysin (CBL) (as a mixture of neurotrophic factors) on the d-galactose-induced oxidative stress, apoptosis and memory as well as learning impairment in mice. For this purpose, CBL (1, 2.5, 5 ml/kg/i.p.) or (1 ml/kg/i.n.), were administrated daily in d-galactose-received (100 mg/kg/subcutaneous (s.c.)) mice model of aging for eight weeks. Spatial and recognition memories were assessed by the Morris water maze and novel object recognition tasks. Brain and blood of animals were analysed for oxidative stress biomarkers including malondialdehyde, total antioxidant capacity, glutathione peroxidase and superoxide dismutase. Apoptosis rate in the hippocampus was evaluated by TUNEL staining of brain tissue. 5 ml/kg/i.p. dose of CBL increased the locomotor activity but, 1 ml/kg/i.p. dose didn't show detectable behavioural or molecular effects on aged mice. Treatment with 2.5 ml/kg/i.p. and 1 ml/kg/i.n. doses attenuated d-galactose-impaired spatial and recognition memories. Results showed an obvious increase in the antioxidant biomarkers and decrease in the malondialdehyde levels both in the blood and brain of aged mice in 2.5 ml/kg/i.p. dose, and only in the brain in 1 ml/kg/i.n. dose of CBL. Anti-apoptotic effects also were seen in the same dose/rout of CBL administration in aged animals. This study proves the usefulness of i.n. CBL administration as a non-invasive and efficient method of drug delivery to the brain to improve aging-induced oxidative stress, apoptosis and learning as well as memory impairment.

The Role of Hypoxia-Inducible Factor 1 in Mild Cognitive Impairment

Neuroinflammation and reactive oxygen species are thought to mediate the pathogenesis of Alzheimer's disease (AD), suggesting that mild cognitive impairment (MCI), a prodromal stage of AD, may be driven by similar insults. Several studies document that hypoxia-inducible factor 1 (HIF-1) is neuroprotective in the setting of neuronal insults, since this transcription factor drives the expression of critical genes that diminish neuronal cell death. HIF-1 facilitates glycolysis and glucose metabolism, thus helping to generate reductive equivalents of NADH/NADPH that counter oxidative stress. HIF-1 also improves cerebral blood flow which opposes the toxicity of hypoxia. Increased HIF-1 activity and/or expression of HIF-1 target genes, such as those involved in glycolysis or vascular flow, may be an early adaptation to the oxidative stressors that characterize MCI pathology. The molecular events that constitute this early adaptation are likely neuroprotective, and might mitigate cognitive decline or the onset of full-blown AD. On the other hand, prolonged or overwhelming stressors can convert HIF-1 into an activator of cell death through agents such as Bnip3, an event that is more likely to occur in late MCI or advanced Alzheimer's dementia.

Iron-chelating agent desferrioxamine stimulates formation of neutrophil extracellular traps (NETs) in human blood-derived neutrophils

Here we show that iron-chelating agent desferrioxamine significantly induced the formation of neutrophil extracellular traps by human blood-derived neutrophils as visualized and quantified by immunofluorescence microscopy. Further analyses characterized biochemical mechanisms associated with the NET formation by desferrioxamine.

Neutrophil extracellular trap (NET) formation is a significant innate immune defense mechanism against microbial infection that complements other neutrophil functions including phagocytosis and degranulation of antimicrobial peptides. NETs are decondensed chromatin structures in which antimicrobial components (histones, antimicrobial peptides and proteases) are deployed and mediate immobilization of microbes. Here we describe an effect of iron chelation on the phenotype of NET formation. Iron-chelating agent desferrioxamine (DFO) showed a modest but significant induction of NETs by freshly isolated human neutrophils as visualized and quantified by immunocytochemistry against histone–DNA complexes. Further analyses revealed that NET induction by iron chelation required NADPH-dependent production of reactive oxygen species (ROS) as well as protease and peptidyl-arginine-deiminase 4 (PAD4) activities, three key mechanistic pathways previously linked to NET formation. Our results demonstrate that iron chelation by DFO contributes to the formation of NETs and suggest a target for pharmacological manipulation of NET activity.

Improving drug delivery technology for treating neurodegenerative diseases

INTRODUCTION

Neurodegenerative diseases (NDs) represent intricate challenges for efficient uptake and transport of drugs to the brain mainly due to the restrictive blood-brain barrier (BBB). NDs are characterized by the loss of neuronal subtypes as sporadic and/or familial and several mechanisms of neurodegeneration have been identified.

AREAS COVERED

This review attempts to recap, organize and concisely evaluate the advanced drug delivery systems designed for treating common NDs. It highlights key research gaps and opinionates on new neurotherapies to overcome the BBB as an addition to the current treatments of countering oxidative stress, inflammation and apoptotic mechanisms.

EXPERT OPINION

Current treatments do not fully address the biological, drug and therapeutic factors faced. This has led to the development of vogue treatments such as nose-to-brain technologies, bio-engineered systems, fusion protein chaperones, stem cells, gene therapy, use of natural compounds, neuroprotectants and even vaccines. However, failure of these treatments is mainly due to the BBB and non-specific delivery in the brain. In order to increase neuroavailability various advanced drug delivery systems provide promising alternatives that are able to augment the treatment of Alzheimer's disease and Parkinson's disease. However, much work is still required in this field beyond the preclinical testing phase.

Deferoxamine-mediated up-regulation of HIF-1α prevents dopaminergic neuronal death via the activation of MAPK family proteins in MPTP-treated mice

Accumulating evidence suggests that an abnormal accumulation of iron in the substantia nigra (SN) is one of the defining characteristics of Parkinson's disease (PD). Accordingly, the potential neuroprotection of Fe chelators is widely acknowledged for the treatment of PD. Although desferrioxamine (DFO), an iron chelator widely used in clinical settings, has been reported to improve motor deficits and dopaminergic neuronal survival in animal models of PD, DFO has poor penetration to cross the blood-brain barrier and elicits side effects. We evaluated whether an intranasal administration of DFO improves the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced degeneration of dopaminergic neurons in the nigrostriatal axis and investigated the molecular mechanisms of intranasal DFO treatment in preventing MPTP-induced neurodegeneration. Treatment with DFO efficiently alleviated behavioral deficits, increased the survival of tyrosine hydroxylase (TH)-positive neurons, and decreased the action of astrocytes in the SN and striatum in an MPTP-induced PD mouse model. Interestingly, we found that DFO up-regulated the expression of HIF-1α protein, TH, vascular endothelial growth factor (VEGF), and growth associated protein 43 (GAP43) and down-regulated the expression of α-synuclein, divalent metal transporter with iron-responsive element (DMT1+IRE), and transferrin receptor (TFR). This was accompanied by a decrease in iron-positive cells in the SN and striatum of the DFO-treated group. We further revealed that DFO treatment significantly inhibited the MPTP-induced phosphorylation of the c-Jun N-terminal kinase (JNK) and differentially enhanced the phosphorylation of extracellular regulated protein kinases (ERK) and mitogen-activated protein kinase (MAPK)/P38 kinase. Additionally, the effects of DFO on increasing the Bcl-2/Bax ratio were further validated in vitro and in vivo. In SH-SY5Y cells, the DFO-mediated up-regulation of HIF-1α occurred via the activation of the ERK and P38MAPK signaling pathway. Collectively, the present data suggest that intranasal DFO treatment is effective in reversing MPTP-induced brain abnormalities and that HIF-1-pathway activation is a potential therapy target for the attenuation of neurodegeneration.

Mechanisms of divalent metal toxicity in affective disorders

Metals are required for proper brain development and play an important role in a number of neurobiological functions. The divalent metal transporter 1 (DMT1) is a major metal transporter involved in the absorption and metabolism of several essential metals like iron and manganese. However, non-essential divalent metals are also transported through this transporter. Therefore, altered expression of DMT1 can modify the absorption of toxic metals and metal-induced toxicity. An accumulating body of evidence has suggested that increased metal stores in the brain are associated with elevated oxidative stress promoted by the ability of metals to catalyze redox reactions, resulting in abnormal neurobehavioral function and the progression of neurodegenerative diseases. Metal overload has also been implicated in impaired emotional behavior, although the underlying mechanisms are not well understood with limited information. The current review focuses on psychiatric dysfunction associated with imbalanced metabolism of metals that are transported by DMT1. The investigations with respect to the toxic effects of metal overload on behavior and their underlying mechanisms of toxicity could provide several new therapeutic targets to treat metal-associated affective disorders.

Delayed emergence of behavioral and electrophysiological effects following juvenile ketamine exposure in mice

Frequent ketamine abuse in adulthood correlates with increased risk of psychosis, as well as cognitive deficits, including disruption of higher-order executive function and memory formation. Although the primary abusers of ketamine are adolescents and young adults, few studies have evaluated its effects on juvenile cognition. Therefore, the current study analyzes the effect of adolescent ketamine exposure on cognitive development. Juvenile mice (4 weeks of age) were exposed to chronic ketamine (20 mg kg(-1), i.p. daily) for 14 days. Mice were tested immediately after exposure in the juvenile period (7 weeks of age) and again as adults (12 weeks of age). Measures included electroencephalography (EEG) in response to auditory stimulation, the social choice test, and a 6-arm radial water maze task. Outcome measures include low-frequency EEG responses, event-related potential (ERP) amplitudes, indices of social behavior and indices of spatial working memory. Juvenile exposure to ketamine was associated with electrophysiological abnormalities in adulthood, particularly in induced theta power and the P80 ERP. The social choice test revealed that ketamine-exposed mice failed to exhibit the same age-related decrease in social interaction time as controls. Ketamine-exposed mice outperformed control mice as juveniles on the radial water maze task, but did not show the same age-related improvement as adult controls. These data support the hypothesis that juvenile exposure to ketamine produces long-lasting changes in brain function that are characterized by a failure to progress along normal developmental trajectories.

Intranasal deferoxamine attenuates synapse loss via up-regulating the P38/HIF-1α pathway on the brain of APP/PS1 transgenic mice

The widely recognized neuroprotective effect of iron chelators is contributed by their ability to prevent reactive oxygen species (ROS) generation via the Fenton reaction, which sequesters redox-active Fe. An additional neuroprotective mechanism of iron-chelating compounds is to regulate the transcriptional activator hypoxia-inducible factor 1α (HIF-1α). In the present study, we observed that intranasal administration of deferoxamine decreased beta-amyloid (Aβ) deposition and rescued synapse loss in the brain of Aβ precursor protein and presenilin-1 (APP/PS1) double transgenic mice. We found that deferoxamine (DFO) up-regulated HIF-1α mRNA expression and its protein level, and further induced the proteins that are encoded from HIF-1-adaptive genes, including transferrin receptor (TFR), divalent metal transporter 1 (DMT1), and brain-derived neurotrophic factor (BDNF). The effects of DFO on the induction and stabilization of HIF-1α were further confirmed in vitro. This was accompanied by a decrease of Fe in the CA3 region of the hippocampus. Western blotting studies revealed that DFO differentially enhanced the phosphorylation of mitogen-activated protein kinase (MAPK)/P38 kinase in vitro and in vivo. The results suggest that the DFO may up-regulate several HIF-1-dependent neuroprotective-adaptive genes in AD via activating P38/HIF-1α pathway, which may serve as important therapeutic targets to the disease.

Solid microparticles based on chitosan or methyl-β-cyclodextrin: a first formulative approach to increase the nose-to-brain transport of deferoxamine mesylate

We propose the formulation and characterization of solid microparticles as nasal drug delivery systems able to increase the nose-to-brain transport of deferoxamine mesylate (DFO), a neuroprotector unable to cross the blood brain barrier and inducing negative peripheral impacts. Spherical chitosan chloride and methyl-β-cyclodextrin microparticles loaded with DFO (DCH and MCD, respectively) were obtained by spray drying. Their volume-surface diameters ranged from 1.77 ± 0.06 μm (DCH) to 3.47 ± 0.05 μm (MCD); the aerodynamic diameters were about 1.1 μm and their drug content was about 30%. In comparison with DCH, MCD enhanced the in vitro DFO permeation across lipophilic membranes, similarly as shown by ex vivo permeation studies across porcine nasal mucosa. Moreover, MCD were able to promote the DFO permeation across monolayers of PC 12 cells (neuron-like), but like DCH, it did not modify the DFO permeation pattern across Caco-2 monolayers (epithelial-like). Nasal administration to rats of 200 μg DFO encapsulated in the microparticles resulted in its uptake into the cerebrospinal fluid (CSF) with peak values ranging from 3.83 ± 0.68 μg/mL (DCH) to 14.37 ± 1.69 μg/mL (MCD) 30 min after insufflation of microparticles. No drug CSF uptake was detected after nasal administration of a DFO water solution. The DFO systemic absolute bioavailabilities obtained by DCH and MCD nasal administration were 6% and 15%, respectively. Chitosan chloride and methyl-β-cyclodextrins appear therefore suitable to formulate solid microparticles able to promote the nose to brain uptake of DFO and to limit its systemic exposure.

Brain Uptake of Neurotherapeutics after Intranasal versus Intraperitoneal Delivery in Mice

There is a growing global prevalence of neurodegenerative diseases such as Alzheimer's disease and dementia. Current treatment for neurodegenerative diseases is limited due to the blood brain barrier's ability to restrict the entry of therapeutics to the brain. In that context, direct delivery of drugs from nose to brain has gained emerging interest as an important alternative to oral and parenteral routes of administration. Although there are considerable reports showing promising results after intranasal drug delivery in various disease-models and investigatory human clinical trials, there are very few studies showing a detailed pharmacokinetics with regard to the uptake and retention of intranasally delivered material(s) within specific brain regions, which are critical determining factors for dosing conditions and optimal treatment regimen. This investigation compared a time-dependent brain uptake and resident time of various radiolabeled candidate neurotherapeutics after a single bolus intranasal or intraperitoneal administration in mice. Results indicate that the brain uptake of intranasally delivered therapeutic(s) is > 5 times greater than that after intraperitoneal delivery. The peak uptake and resident time of all intranasally delivered test therapeutics for all brain regions is observed to be between 30min-12h, depending upon the distance of brain region from the site of administration, followed by gradual fading of radioactive counts by 24h post intranasal administration. Current study confirms the usefulness of intranasal administration as a non- invasive and efficient means of delivering therapeutics to the brain to treat neurodegenerative diseases including Alzheimer's disease.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

Intranasal therapeutic strategies for management of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and progressive age-related irreversible neurodegenerative disorder that represents 70% of all dementia with 35 million cases worldwide. Successful treatment strategies for AD have so far been limited, and present therapy is based on cholinergic replacement therapy and inhibiting glutamate excitotoxicity. In this context, role of neuroprotective drugs has generated considerable interest in management of AD. Recently, direct intranasal (IN) delivery of drug moieties to the central nervous system (CNS) has emerged as a therapeutically viable alternative to oral and parenteral routes. IN delivery bypasses the blood-brain barrier by delivering and targeting drugs to the CNS along the olfactory and trigeminal neural pathways which are in direct contact with both the environment and the CNS. In an attempt to understand how neurotherapeutics/nanoparticulate delivery systems can be transported from the nose to the CNS, the present review sets out to discuss the mechanism of transport from nose to brain. The aim of this review is to discuss and summarize the latest findings of some of the major studies on IN drug delivery in AD models, with a focus on the potential efficacy of neuroprotective treatments.

Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by "antioxidant" metal chelators: From ferroptosis to stroke

Neurologic conditions including stroke, Alzheimer disease, Parkinson disease, and Huntington disease are leading causes of death and long-term disability in the United States, and efforts to develop novel therapeutics for these conditions have historically had poor success in translating from bench to bedside. Hypoxia-inducible factor (HIF)-1α mediates a broad, evolutionarily conserved, endogenous adaptive program to hypoxia, and manipulation of components of the HIF pathway is neuroprotective in a number of human neurological diseases and experimental models. In this review, we discuss molecular components of one aspect of hypoxic adaptation in detail and provide perspective on which targets within this pathway seem to be ripest for preventing and repairing neurodegeneration. Further, we highlight the role of HIF prolyl hydroxylases as emerging targets for the salutary effects of metal chelators on ferroptosis in vitro as well in animal models of neurological diseases.