Ciliary neurotrophic factor cell-based delivery prevents synaptic impairment and improves memory in mouse models of Alzheimer's disease

Mediterranean diet protects against a neuroinflammatory cortical transcriptome: Associations with brain volumetrics, peripheral inflammation, social isolation, and anxiety in nonhuman primates (Macaca fascicularis)

Mediterranean diets may be neuroprotective and prevent cognitive decline relative to Western diets; however, the underlying biology is poorly understood. We assessed the effects of Western versus Mediterranean-like diets on RNAseq-generated transcriptional profiles in lateral temporal cortex and their relationships with longitudinal changes in neuroanatomy, circulating monocyte gene expression, and observations of social isolation and anxiety in 38 socially-housed, middle-aged female cynomolgus macaques (Macaca fascicularis). Diet resulted in differential expression of seven transcripts (FDR < 0.05). Cyclin dependent kinase 14 (CDK14), a proinflammatory regulator, was lower in the Mediterranean group. The remaining six transcripts [i.e., "lunatic fringe" (LFNG), mannose receptor C type 2 (MRC2), solute carrier family 3 member 2 (SLCA32), butyrophilin subfamily 2 member A1 (BTN2A1), katanin regulatory subunit B1 (KATNB1), and transmembrane protein 268 (TMEM268)] were higher in cortex of the Mediterranean group and generally associated with anti-inflammatory/neuroprotective pathways. KATNB1 encodes a subcomponent of katanin, important in maintaining microtubule homeostasis. BTN2A1 is involved in immunomodulation of γδ T-cells which have anti-neuroinflammatory and neuroprotective effects. CDK14, LFNG, MRC2, and SLCA32 are associated with inflammatory pathways. The latter four differentially expressed cortex transcripts were associated with peripheral monocyte transcript levels, neuroanatomical changes determined by MRI, and with social isolation and anxiety. These results provide important insights into the potential mechanistic processes linking diet, peripheral and central inflammation, and behavior. Collectively, our results provide evidence that, relative to Western diets, Mediterranean diets confer protection against peripheral and central inflammation which is reflected in preserved brain structure and socioemotional behavior. Ultimately, such protective effects may confer resilience to the development of neuropathology and associated disease.

Astrocyte focal adhesion kinase reduces passive stress coping by inhibiting ciliary neurotrophic factor only in female mice

Astrocytes have been implicated in stress responses and produce ciliary neurotrophic factor (CNTF), which we have shown in the mouse medial amygdala (MeA) to promote passive stress coping response only in females. Pharmacological inhibition of focal adhesion kinase (FAK) upregulates CNTF expression. Here, we found that inducible knockout of FAK in astrocytes or systemic treatment with an FAK inhibitor increased passive coping behavior, i.e., immobility, in an acute forced swim stress test in female, but not male, mice. Strikingly, four weeks of chronic unpredictable stress (CUS) did not further increase passive coping in female astrocytic FAK knockout mice, whereas it exacerbated it in female wildtype mice and male mice of both genotypes. These data suggest that astrocyte FAK inhibition is required for chronic stress-induced passive coping in females. Indeed, CUS reduced phospho-FAK and increased CNTF in the female MeA. Progesterone treatment after ovariectomy activated amygdala FAK and alleviated ovariectomy-induced passive coping in wildtype, but not astrocytic FAK knockout females. This suggests that progesterone-mediated activation of FAK in astrocytes reduces female stress responses. Finally, astrocytic FAK knockout or FAK inhibitor treatment increased CNTF expression in the MeA of both sexes, although not in the hippocampus. As mentioned, MeA CNTF promotes stress responses only in females, which may explain the female-specific role of astrocytic FAK inhibition. Together, this study reveals a novel female-specific progesterone-astrocytic FAK pathway that counteracts CNTF-mediated stress responses and points to opportunities for developing treatments for stress-related disorders in women.

Aging-Related Protein Alterations in the Brain

Aging is an intrinsic aspect of an organism's life cycle and is characterized by progressive physiological decline and increased susceptibility to mortality. Many age-associated disorders, including neurological disorders, are most commonly linked with the aging process, such as Alzheimer's disease (AD). This review aims to provide a comprehensive overview of the effects of aging and AD on the molecular pathways and levels of different proteins in the brain, including metalloproteins, neurotrophic factors, amyloid proteins, and tau proteins. AD is caused by the aggregation of amyloid proteins in the brain. Factors such as metal ions, protein ligands, and the oligomerization state of amyloid precursor protein significantly influence the proteolytic processing of amyloid-β protein precursor (AβPP). Tau, a disordered cytosolic protein, serves as the principal microtubule-associated protein in mature neurons. AD patients exhibit decreased levels of nerve growth factor within their nervous systems and cerebrospinal fluid. Furthermore, a significant increase in brain-derived neurotrophic factor resulting from the neuroprotective effect of glial cell line-derived neurotrophic factor suggests that the synergistic action of these proteins plays a role in inhibiting neuronal degeneration and atrophy. The mechanism through which Aβ and AβPP govern Cu2+ transport and their influence on Cu2+ and other metal ion pools requires elucidation in future studies. A comprehensive understanding of the influence of aging and AD on molecular pathways and varying protein levels may hold the potential for the development of novel diagnostic and therapeutic methods for the treatment of AD.

Mediterranean Diet Protects Against a Neuroinflammatory Cortical Transcriptome: Associations with Brain Volumetrics, Peripheral Inflammation, Social Isolation and Anxiety

INTRODUCTION

Mediterranean diets may be neuroprotective and prevent cognitive decline relative to Western diets, however the underlying biology is poorly understood.

METHODS

We assessed the effects of Western vs. Mediterranean-like diets on RNAseq generated transcriptional profiles in temporal cortex and their relationships with changes in MRI neuroimaging phenotypes, circulating monocyte gene expression, and observations of social isolation and anxiety in 38 socially-housed, middle-aged female cynomolgus macaques.

RESULTS

Diet resulted in differential expression of seven transcripts (FDR<0.05). Cyclin dependent kinase 14 ( CDK14 ), a proinflammatory regulator, was lower in the Mediterranean group. The remaining six transcripts [i.e., "lunatic fringe" ( LFNG ), mannose receptor C type 2 ( MRC2 ), solute carrier family 3 member 2 ( SLCA32 ), butyrophilin subfamily 2 member A1 ( BTN2A1 ), katanin regulatory subunit B1 ( KATNB1 ), and transmembrane protein 268 ( TMEM268 )] were higher in cortex of the Mediterranean group and generally associated with anti-inflammatory/neuroprotective pathways. KATNB1 encodes a subcomponent of katanin, important in maintaining microtubule homeostasis. BTN2A1 is involved in immunomodulation of γδ T-cells which have anti-neuroinflammatory and neuroprotective effects. CDK14 , LFNG , MRC2, and SLCA32 are associated with inflammatory pathways. The latter four differentially expressed cortex transcripts were associated with monocyte transcript levels, changes in AD-relevant brain volumes determined by MRI over the course of the study, and social isolation and anxiety. CDK14 was positively correlated with monocyte inflammatory transcripts, changes in total brain, gray matter, cortical gray matter volumes, and time alone and anxious behavior, and negatively correlated with changes in total white matter and cerebrospinal fluid (CSF) volumes. In contrast, LFNG , MRC2 , and SLCA32 were negatively correlated with monocyte inflammatory transcripts and changes in total gray matter volume, and positively correlated with CSF volume changes, and SLCA32 was negatively correlated with time alone.

DISCUSSION

Collectively, our results suggest that relative to Western diets, Mediterranean diets confer protection against peripheral and central inflammation which is reflected in preserved brain structure and behavior.

Fiber deprivation and microbiome-borne curli shift gut bacterial populations and accelerate disease in a mouse model of Parkinson's disease

Parkinson's disease (PD) is a neurological disorder characterized by motor dysfunction, dopaminergic neuron loss, and alpha-synuclein (αSyn) inclusions. Many PD risk factors are known, but those affecting disease progression are not. Lifestyle and microbial dysbiosis are candidates in this context. Diet-driven gut dysbiosis and reduced barrier function may increase exposure of enteric neurons to toxins. Here, we study whether fiber deprivation and exposure to bacterial curli, a protein cross-seeding with αSyn, individually or together, exacerbate disease in the enteric and central nervous systems of a transgenic PD mouse model. We analyze the gut microbiome, motor behavior, and gastrointestinal and brain pathologies. We find that diet and bacterial curli alter the microbiome and exacerbate motor performance, as well as intestinal and brain pathologies, but to different extents. Our results shed important insights on how diet and microbiome-borne insults modulate PD progression via the gut-brain axis and have implications for lifestyle management of PD.

Cell Encapsulation and 3D Bioprinting for Therapeutic Cell Transplantation

The promise of cell therapy has been augmented by introducing biomaterials, where intricate scaffold shapes are fabricated to accommodate the cells within. In this review, we first discuss cell encapsulation and the promising potential of biomaterials to overcome challenges associated with cell therapy, particularly cellular function and longevity. More specifically, cell therapies in the context of autoimmune disorders, neurodegenerative diseases, and cancer are reviewed from the perspectives of preclinical findings as well as available clinical data. Next, techniques to fabricate cell-biomaterials constructs, focusing on emerging 3D bioprinting technologies, will be reviewed. 3D bioprinting is an advancing field that enables fabricating complex, interconnected, and consistent cell-based constructs capable of scaling up highly reproducible cell-biomaterials platforms with high precision. It is expected that 3D bioprinting devices will expand and become more precise, scalable, and appropriate for clinical manufacturing. Rather than one printer fits all, seeing more application-specific printer types, such as a bioprinter for bone tissue fabrication, which would be different from a bioprinter for skin tissue fabrication, is anticipated in the future.

Cell-based drug delivery systems and their in vivo fate

Cell-based drug delivery systems (DDSs) have received attention recently because of their unique biological properties and self-powered functions, such as excellent biocompatibility, low immunogenicity, long circulation time, tissue-homingcharacteristics, and ability to cross biological barriers. A variety of cells, including erythrocytes, stem cells, and lymphocytes, have been explored as functional vectors for the loading and delivery of various therapeutic payloads (e.g., small-molecule and nucleic acid drugs) for subsequent disease treatment. These cell-based DDSs have their own unique in vivo fates, which are attributed to various factors, including their biological properties and functions, the loaded drugs and loading process, physiological and pathological circumstances, and the body's response to these carrier cells, which result in differences in drug delivery efficiency and therapeutic effect. In this review, we summarize the main cell-based DDSs and their biological properties and functions, applications in drug delivery and disease treatment, and in vivo fate and influencing factors. We envision that the unique biological properties, combined with continuing research, will enable development of cell-based DDSs as friendly drug vectors for the safe, effective, and even personalized treatment of diseases.

An alginate-based encapsulation system for delivery of therapeutic cells to the CNS

Treatment options for neurodegenerative conditions such as Parkinson's disease have included the delivery of cells which release dopamine or neurotrophic factors to the brain. Here, we report the development of a novel approach for protecting cells after implantation into the central nervous system (CNS), by developing dual-layer alginate beads that encapsulate therapeutic cells and release an immunomodulatory compound in a sustained manner. An optimal alginate formulation was selected with a view to providing a sustained physical barrier between engrafted cells and host tissue, enabling exchange of small molecules while blocking components of the host immune response. In addition, a potent immunosuppressant, FK506, was incorporated into the outer layer of alginate beads using electrosprayed poly-ε-caprolactone core–shell nanoparticles with prolonged release profiles. The stiffness, porosity, stability and ability of the alginate beads to support and protect encapsulated SH-SY5Y cells was demonstrated, and the release profile of FK506 and its effect on T-cell proliferation in vitro was characterized. Collectively, our results indicate this multi-layer encapsulation technology has the potential to be suitable for use in CNS cell delivery, to protect implanted cells from host immune responses whilst providing permeability to nutrients and released therapeutic molecules.

Novel composite cell encapsulation system: dual-layer, micro-scale beads maintain cell survival while releasing immunomodulatory FK506 in a sustained manner. This biotechnology platform could be applicable for treatment of CNS and other disorders.

Therapeutic potential of neurotrophic factors in Alzheimer's Disease

INTRODUCTION

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia among the elderly population. AD is accompanied with the dysregulation of specific neurotrophic factors (NTFs) and their receptors, which plays a critical role in neuronal degeneration. NTFs are small proteins with therapeutic potential for human neurodegenerative diseases. These growth factors are categorized into four families: neurotrophins, neurokines, the glial cell line-derived NTF family of ligands, and the newly discovered cerebral dopamine NTF/mesencephalic astrocyte-derived NTF family. NTFs are capable of preventing cell death in degenerative conditions and can increase the neuronal growth and function in these disorders. Nevertheless, the adverse side effects of NTFs delivery and poor diffusion of these factors in the brain restrict the efficacy of NTFs therapy in clinical situations.

MATERIALS AND METHODS

In this review, we focus on the current advances in the use of NTFs to treat AD and summarize previous experimental and clinical studies for supporting the protective and therapeutic effects of these factors.

CONCLUSION

Based on reports, NTFs are considered as new and promising candidates for treating AD and AD-associated cognitive impairment.

A Novel Selective PKR Inhibitor Restores Cognitive Deficits and Neurodegeneration in Alzheimer Disease Experimental Models

In Alzheimer disease (AD), the double-strand RNA-dependent kinase protein kinase R (PKR )/EIF2AK2 is activated in brain with increased phosphorylation of its substrate eukaryotic initiation factor 2α (eIF2α). AD risk-promoting factors, such as ApoE4 allele or the accumulation of neurotoxic amyloid-β oligomers (AβOs), have been associated with activation of PKR-dependent signaling. Here, we report the discovery of a novel potent and selective PKR inhibitor (SAR439883) and demonstrate its neuroprotective pharmacological activity in AD experimental models. In ApoE4 human replacement male mice, 1-week oral treatment with SAR439883 rescued short-term memory impairment in the spatial object recognition test and dose-dependently reduced learning and memory deficits in the Barnes maze test. Moreover, in AβO-injected male mice, a 2-week administration of SAR439883 in diet dose-dependently ameliorated the AβO-induced cognitive impairment in both Y-maze and Morris Water Maze, prevented loss of synaptic proteins, and reduced levels of the proinflammatory cytokine interleukin-1β In both mouse models, these effects were associated with a dose-dependent inhibition of brain PKR activity as measured by both PKR occupancy and partial lowering of peIF2α levels. Our results provide evidence that selective pharmacological inhibition of PKR by a small selective molecule can rescue memory deficits and prevent neurodegeneration in animal models of AD-like pathology, suggesting that inhibition of PKR is a potential therapeutic approach for AD. SIGNIFICANCE STATEMENT: This study reports the identification of a new small molecule potent and selective protein kinase R (PKR) inhibitor that can prevent cognitive deficits and neurodegeneration in Alzheimer disease (AD) experimental models, including a mouse model expressing the most prevalent AD genetic risk factor ApoE4. With high potency and selectivity, this PKR inhibitor represents a unique tool for investigating the physiological role of PKR and a starting point for developing new drug candidates for AD.

Neuroprotective and Symptomatic Effects of Cannabidiol in an Animal Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the Substantia Nigra pars compacta, leading to classical PD motor symptoms. Current therapies are purely symptomatic and do not modify disease progression. Cannabidiol (CBD), one of the main phytocannabinoids identified in Cannabis Sativa, which exhibits a large spectrum of therapeutic properties, including anti-inflammatory and antioxidant effects, suggesting its potential as disease-modifying agent for PD. The aim of this study was to evaluate the effects of chronic treatment with CBD (10 mg/kg, i.p.) on PD-associated neurodegenerative and neuroinflammatory processes, and motor deficits in the 6-hydroxydopamine model. Moreover, we investigated the potential mechanisms by which CBD exerted its effects in this model. CBD-treated animals showed a reduction of nigrostriatal degeneration accompanied by a damping of the neuroinflammatory response and an improvement of motor performance. In particular, CBD exhibits a preferential action on astrocytes and activates the astrocytic transient receptor potential vanilloid 1 (TRPV1), thus, enhancing the endogenous neuroprotective response of ciliary neurotrophic factor (CNTF). These results overall support the potential therapeutic utility of CBD in PD, as both neuroprotective and symptomatic agent.

Mapping Post-Translational Modifications in Brain Regions in Alzheimer's Disease Using Proteomics Data Mining

Alzheimer's disease (AD) is a leading cause of dementia and a neurodegenerative disease. Proteomics and post-translational modification (PTM) analyses offer new opportunities for a comprehensive understanding of pathophysiology of brain in AD. We report here multiple PTMs in patients with AD, harnessing publicly available proteomics data from nine brain regions and at three different Braak stages of disease progression. Specifically, we identified 7190 peptides with PTMs, corresponding to 2545 proteins from brain regions with intermediate tangles, and 6864 peptides with PTMs corresponding to 2465 proteins from brain regions with severe tangles. A total of 103 proteins with PTMs were expressed uniquely to intermediate tangles and severe tangles compared to no tangles. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis suggested the association of these proteins in AD progression through platelet activation. These modified proteins were also found to be enriched for the tricarboxylic acid (TCA) cycle, respiratory electron cycle, and detoxification of reactive oxygen species. The multi-PTM data reported here contribute to our understanding of the neurobiology of AD and highlight the prospects of omics systems science research in neurodegenerative diseases. The present study provides a region-wise classification for the proteins with PTMs along with their differential expression patterns, providing insights into the localization of these proteins upon modification. The catalog of multi-PTMs identified in the context of AD from different brain regions provides a unique platform for generating newer hypotheses in understanding the putative role of specific PTMs in AD pathogenesis.

Proteome Analysis of PC12 Cells Reveals Alterations in Translation Regulation and Actin Signaling Induced by Clozapine

Although antipsychotics are routinely used in the treatment of schizophrenia for the last decades, their precise mechanism of action is still unclear. In this study, we investigated changes in the PC12 cells’ proteome under the influence of clozapine, risperidone, and haloperidol to identify protein pathways regulated by antipsychotics. Analysis of the protein profiles in two time points: after 12 and 24 h of incubation with drugs revealed significant alterations in 510 proteins. Further canonical pathway analysis revealed an inhibition of ciliary trophic factor signaling after treatment with haloperidol and showed a decrease in acute phase response signaling in the risperidone group. Interestingly, all tested drugs have caused changes in PC12 proteome which correspond to inhibition of cytokines: tumor necrosis factor (TNF) and transforming growth factor beta 1 (TGF-β1). We also found that the 12-h incubation with clozapine caused up-regulation of protein kinase A signaling and translation machinery. After 24 h of treatment with clozapine, the inhibition of the actin cytoskeleton signaling and Rho proteins signaling was revealed. The obtained results suggest that the mammalian target of rapamycin complex 1 (mTORC1) and 2 (mTORC2) play a central role in the signal transduction of clozapine.

Therapeutic Potential of AAV1-Rheb(S16H) Transduction against Neurodegenerative Diseases

Neurotrophic factors (NTFs) are essential for cell growth, survival, synaptic plasticity, and maintenance of specific neuronal population in the central nervous system. Multiple studies have demonstrated that alterations in the levels and activities of NTFs are related to the pathology and symptoms of neurodegenerative disorders, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and Huntington’s disease. Hence, the key molecule that can regulate the expression of NTFs is an important target for gene therapy coupling adeno-associated virus vector (AAV) gene. We have previously reported that the Ras homolog protein enriched in brain (Rheb)–mammalian target of rapamycin complex 1 (mTORC1) axis plays a vital role in preventing neuronal death in the brain of AD and PD patients. AAV transduction using a constitutively active form of Rheb exerts a neuroprotective effect through the upregulation of NTFs, thereby promoting the neurotrophic interaction between astrocytes and neurons in AD conditions. These findings suggest the role of Rheb as an important regulator of the regulatory system of NTFs to treat neurodegenerative diseases. In this review, we present an overview of the role of Rheb in neurodegenerative diseases and summarize the therapeutic potential of AAV serotype 1 (AAV1)-Rheb(S16H) transduction in the treatment of neurodegenerative disorders, focusing on diseases, such as AD and PD.

Exploring the Role of Gene Therapy for Neurological Disorders

Gene therapy is one of the frontier fields of medical breakthroughs that poses as an effective solution to previously incurable diseases. The delivery of the corrective genetic material or a therapeutic gene into the cell restores the missing gene function and cures a plethora of diseases, incurable by the conventional medical approaches. This discovery holds the potential to treat many neurodegenerative disorders such as muscular atrophy, multiple sclerosis, Parkinson's disease (PD) and Alzheimer's disease (AD), among others. Gene therapy proves as a humane, cost-effective alternative to the exhaustive often arduous and timely impossible process of finding matched donors and extensive surgery. It also overcomes the shortcoming of conventional methods to cross the blood-brain barrier. However, the use of gene therapy is only possible after procuring the in-depth knowledge of the immuno-pathogenesis and molecular mechanism of the disease. The process of gene therapy can be broadly categorized into three main steps: elucidating the target gene, culling the appropriate vector, and determining the best mode of transfer; each step mandating pervasive research. This review aims to dissertate and summarize the role, various vectors and methods of delivery employed in gene therapy with special emphasis on therapy directed at the central nervous system (CNS) associated with neurodegenerative diseases.

Genetically modified macrophages accomplish targeted gene delivery to the inflamed brain in transgenic Parkin Q311X(A) mice: importance of administration routes

Cell-based drug delivery systems have generated an increasing interest in recent years. We previously demonstrated that systemically administered macrophages deliver therapeutics to CNS, including glial cell line-derived neurotrophic factor (GDNF), and produce potent effects in Parkinson’s disease (PD) mouse models. Herein, we report fundamental changes in biodistribution and brain bioavailability of macrophage-based formulations upon different routes of administration: intravenous, intraperitoneal, or intrathecal injections. The brain accumulation of adoptively transferred macrophages was evaluated by various imaging methods in transgenic Parkin Q311(X)A mice and compared with those in healthy wild type littermates. Neuroinflammation manifested in PD mice warranted targeting macrophages to the brain for each route of administration. The maximum amount of cell-carriers in the brain, up to 8.1% ID/g, was recorded followed a single intrathecal injection. GDNF-transfected macrophages administered through intrathecal route provided significant increases of GDNF levels in different brain sub-regions, including midbrain, cerebellum, frontal cortex, and pons. No significant offsite toxicity of the cell-based formulations in mouse brain and peripheral organs was observed. Overall, intrathecal injection appeared to be the optimal administration route for genetically modified macrophages, which accomplished targeted gene delivery, and significant expression of reporter and therapeutic genes in the brain.

Anti-aging properties of Dendrobium nobile Lindl.: From molecular mechanisms to potential treatments

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium Nobile Lindl. (DNL) is one of the central herbs in traditional Chinese medicine which mainly distributes in Guizhou, Yunnan, Guangxi and other sub-tropical areas south of the Yangtze River. In the past decades, it has been used to treat tumors, hyperglycemia, hyperlipidemia, and diseases of the nervous system that may be caused by aging.

AIM OF THE REVIEW

The purpose of this review is to summarize the anti-aging information of DNL from the molecular mechanism level, including classic theories related to aging, main chemical components, pharmacological research and anti-aging theory based on traditional Chinese medicine theory, for exploring the future development and clinical treatment.

MATERIALS AND METHODS

The information in this paper has been collected from the scientific literature databases including PubMed, Google Scholar, Web of Science, Science Direct, Springer, China National Knowledge Infrastructure, published books, Ph.D. and M.S. dissertations systematically.

RESULTS

In this paper, we have reviewed the several mechanisms underlying the potential effects of DNL on the prevention of aging, including the scavenging of free radicals for oxidation, delaying of DNA impairment, inhibition of apoptosis, and alteration of DNA methylation. Together with the theory of telomeres, this review also has summarized recent research progress in the use of DNL and its traditional efficacy.

CONCLUSIONS

We conclude that "strengthening Yin and benefiting the spirit", "thickening the intestine and stomach", "lightning the body and prolonging the life-span", and delaying aging, are key effects of DNL that can be used to combat age-related diseases (ARDs) such as Alzheimer's disease, hyperlipidemia, and diabetes. This review provides a reference for future study of ARDs and the clinical application of DNL.

Synaptosome as a tool in Alzheimer's disease research

Synapse dysfunction is an integral feature of Alzheimer's disease (AD) pathophysiology. In fact, prodromal manifestation of structural and functional deficits in synapses much prior to appearance of overt pathological hallmarks of the disease indicates that AD might be considered as a degenerative disorder of the synapses. Several research instruments and techniques have allowed us to study synaptic function and plasticity and their alterations in pathological conditions, such as AD. One such tool is the biochemically isolated preparations of detached and resealed synaptic terminals, the "synaptosomes". Because of the preservation of many of the physiological processes such as metabolic and enzymatic activities, synaptosomes have proved to be an indispensable ex vivo model system to study synapse physiology both when isolated from fresh or cryopreserved tissues, and from animal or human post-mortem tissues. This model system has been tremendously successful in the case of post-mortem tissues because of their accessibility relative to acute brain slices or cultures. The current review details the use of synaptosomes in AD research and its potential as a valuable tool in furthering our understanding of the pathogenesis and in devising and testing of therapeutic strategies for the disease.

Biomaterials for Personalized Cell Therapy

Cell therapy has already had an important impact on healthcare and provided new treatments for previously intractable diseases. Notable examples include mesenchymal stem cells for tissue regeneration, islet transplantation for diabetes treatment, and T cell delivery for cancer immunotherapy. Biomaterials have the potential to extend the therapeutic impact of cell therapies by serving as carriers that provide 3D organization and support cell viability and function. With the growing emphasis on personalized medicine, cell therapies hold great potential for their ability to sense and respond to the biology of an individual patient. These therapies can be further personalized through the use of patient-specific cells or with precision biomaterials to guide cellular activity in response to the needs of each patient. Here, the role of biomaterials for applications in tissue regeneration, therapeutic protein delivery, and cancer immunotherapy is reviewed, with a focus on progress in engineering material properties and functionalities for personalized cell therapies.

Upregulation of Neuronal Rheb(S16H) for Hippocampal Protection in the Adult Brain

Ras homolog protein enriched in brain (Rheb) is a key activator of mammalian target of rapamycin complex 1 (mTORC1). The activation of mTORC1 by Rheb is associated with various processes such as protein synthesis, neuronal growth, differentiation, axonal regeneration, energy homeostasis, autophagy, and amino acid uptake. In addition, Rheb-mTORC1 signaling plays a crucial role in preventing the neurodegeneration of hippocampal neurons in the adult brain. Increasing evidence suggests that the constitutive activation of Rheb has beneficial effects against neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Our recent studies revealed that adeno-associated virus serotype 1 (AAV1) transduction with Rheb(S16H), a constitutively active form of Rheb, exhibits neuroprotective properties through the induction of various neurotrophic factors, promoting neurotrophic interactions between neurons and astrocytes in the hippocampus of the adult brain. This review provides compelling evidence for the therapeutic potential of AAV1-Rheb(S16H) transduction in the hippocampus of the adult brain by exploring its neuroprotective effects and mechanisms.

Donecopride, a Swiss army knife with potential against Alzheimer's disease

BACKGROUND AND PURPOSE

We recently identified donecopride as a pleiotropic compound able to inhibit AChE and to activate 5-HT₄ receptors. Here, we have assessed the potential therapeutic effects of donecopride in treating Alzheimer's disease (AD).

EXPERIMENTAL APPROACH

We used two in vivo animal models of AD, transgenic 5XFAD mice and mice exposed to soluble amyloid-β peptides and, in vitro, primary cultures of rat hippocampal neurons. Pro-cognitive and anti-amnesic effects were evaluated with novel object recognition, Y-maze, and Morris water maze tests. Amyloid load in mouse brain was measured ex vivo and effects of soluble amyloid-β peptides on neuronal survival and neurite formation determined in vitro.

KEY RESULTS

In vivo, chronic (3 months) administration of donecopride displayed potent anti-amnesic properties in the two mouse models of AD, preserving learning capacities, including working and long-term spatial memories. These behavioural effects were accompanied by decreased amyloid aggregation in the brain of 5XFAD mice and, in cultures of rat hippocampal neurons, reduced tau hyperphosphorylation. In vitro, donecopride increased survival in neuronal cultures exposed to soluble amyloid-β peptides, improved the neurite network and provided neurotrophic benefits, expressed as the formation of new synapses.

CONCLUSIONS AND IMPLICATIONS

Donecopride acts like a Swiss army knife, exhibiting a range of sustainable symptomatic therapeutic effects and potential disease-modifying effects in models of AD. Clinical trials with this promising drug candidate will soon be undertaken to confirm its therapeutic potential in humans.

Neurotrophic interactions between neurons and astrocytes following AAV1-Rheb(S16H) transduction in the hippocampus in vivo

Background and Purpose

We recently reported that AAV1‐Rheb(S16H) transduction could protect hippocampal neurons through the induction of brain‐derived neurotrophic factor (BDNF) in the rat hippocampus in vivo. It is still unclear how neuronal BDNF produced by AAV1‐Rheb(S16H) transduction induces neuroprotective effects in the hippocampus and whether its up‐regulation contributes to the enhance of a neuroprotective system in the adult brain.

Experimental Approach

To determine the presence of a neuroprotective system in the hippocampus of patients with Alzheimer's disease (AD), we examined the levels of glial fibrillary acidic protein, BDNF and ciliary neurotrophic factor (CNTF) and their receptors, tropomyocin receptor kinase B (TrkB) and CNTF receptor α(CNTFRα), in the hippocampus of AD patients. We also determined whether AAV1‐Rheb(S16H) transduction stimulates astroglial activation and whether reactive astrocytes contribute to neuroprotection in models of hippocampal neurotoxicity in vivo and in vitro.

Key Results

AD patients may have a potential neuroprotective system, demonstrated by increased levels of full‐length TrkB and CNTFRα in the hippocampus. Further AAV1‐Rheb(S16H) transduction induced sustained increases in the levels of full‐length TrkB and CNTFRα in reactive astrocytes and hippocampal neurons. Moreover, neuronal BDNF produced by Rheb(S16H) transduction of hippocampal neurons induced reactive astrocytes, resulting in CNTF production through the activation of astrocytic TrkB and the up‐regulation of neuronal BDNF and astrocytic CNTF which had synergistic effects on the survival of hippocampal neurons in vivo.

Conclusions and Implications

The results demonstrated that Rheb(S16H) transduction of hippocampal neurons could strengthen the neuroprotective system and this intensified system may have a therapeutic value against neurodegeneration in the adult brain.

Cell Encapsulation Within Alginate Microcapsules: Immunological Challenges and Outlook

Cell encapsulation is a bioengineering technology that provides live allogeneic or xenogeneic cells packaged in a semipermeable immune-isolating membrane for therapeutic applications. The concept of cell encapsulation was first proposed almost nine decades ago, however, and despite its potential, the technology has yet to deliver its promise. The few clinical trials based on cell encapsulation have not led to any licensed therapies. Progress in the field has been slow, in part due to the complexity of the technology, but also because of the difficulties encountered when trying to prevent the immune responses generated by the various microcapsule components, namely the polymer, the encapsulated cells, the therapeutic transgenes and the DNA vectors used to genetically engineer encapsulated cells. While the immune responses induced by polymers such as alginate can be minimized using highly purified materials, the need to cope with the immunogenicity of encapsulated cells is increasingly seen as key in preventing the immune rejection of microcapsules. The encapsulated cells are recognized by the host immune cells through a bidirectional exchange of immune mediators, which induce both the adaptive and innate immune responses against the engrafted capsules. The potential strategies to cope with the immunogenicity of encapsulated cells include the selective diffusion restriction of immune mediators through capsule pores and more recently inclusion in microcapsules of immune modulators such as CXCL12. Combining these strategies with the use of well-characterized cell lines harboring the immunomodulatory properties of stem cells should encourage the incorporation of cell encapsulation technology in state-of-the-art drug development.

New treatment modalities in Alzheimer's disease

Alzheimer’s disease (AD) is still a major public health challenge without an effective treatment to prevent or stop it. Routinely used acetylcholinesterase inhibitors and memantine seem to slow disease progression only to a limited extend. Therefore, many investigations on new drugs and other treatment modalities are ongoing in close association with increasing knowledge of the pathophysiology of the disease. Here, we review the studies about the new treatment modalities in AD with a classification based on their main targets, specifically pathologic structures of the disease, amyloid and tau, neural network dysfunction with special interest to the regulation of gamma oscillations, and attempts for the restoration of neural tissue via regenerative medicine. Additionally, we describe the evolving modalities related to gut microbiota, modulation, microglial function, and glucose metabolism.

Neurotrophic Factors Mediated Activation of Astrocytes Ameliorate Memory Loss by Amyloid Clearance after Transplantation of Lineage Negative Stem Cells

Alzheimer's disease (AD) is one of the untreatable neurodegenerative disorders with associated societal burden. Current therapies only provide symptomatic relief without altering the rate of disease progression as reported by Lanctot et al. (Therapeutic Advances in Neurological Disorders 2 (3):163-180, 2009). The increased number of failed clinical trials in last two decades indicates the imperative need to explore alternative therapies for AD as reported by Tuszynski et al. (Nature Medicine 11 (5):551-555, 2005) and Liyanage et al. (Alzheimer's & Dementia 4:628-635, 2005). In this study, we aimed to decipher the role of neurotrophic factors in the reversal of memory loss by transplantation of lineage negative (Lin-ve) stem cells in a male mouse model of cognitive impairment induced by intrahippocampal injection of amyloid β-42 (Aβ-42). The efficacy of human umbilical cord blood (hUCB) derived Lin-ve stem cells were analyzed by neurobehavioral parameters, i.e., Morris water maze and passive avoidance after bilateral intra-hippocampal transplantation using stereotaxic surgery. Real-time PCR and immunohistochemistry was carried out in brain tissues in order to analyze the expression of neurotrophic factors, apoptotic, astrocytic, and other neuronal cell markers. The transplantation of Lin-ve stem cells led to reversal of memory loss associated with reduction of Aβ-42 deposition from the brains. The molecular analysis revealed increase in neurotrophic factors, i.e., glial derived neurotrophic factor (GDNF), ciliary derived neurotrophic factor (CNTF), and Brain-derived neurotrophic factor (BDNF) after transplantation. The administration of ANA-12, a TrkB inhibitor, reversed the behavioral and molecular effects of stem cell transplantation suggesting involvement of BDNF-TrkB pathway in the rescue of memory loss. We believe that the amyloid clearance results from activation of astrocytes and anti-apoptotic pathways added by neurotrophic factors.

Xanthoceraside prevented synaptic loss and reversed learning-memory deficits in APP/PS1 transgenic mice

Xanthoceraside, a novel triterpenoid saponin, has been found to attenuate learning and memory impairments in AD animal models. However, whether xanthoceraside has a positive effect on synaptic morphology remains unclear. Herein, we evaluated the effects of xanthoceraside on learning and memory impairments and the abnormalities of synaptic structure in APP/PS1 transgenic mice. The behavioral experiments demonstrated that xanthoceraside attenuated the imaginal memory and spatial learning impairments, and improved social interaction. Transmission electron microscopy and Golgi staining showed that xanthoceraside ameliorated synapse morphology abnormalities and dendritic spine density deficits, respectively. Western-blot analysis identified that xanthoceraside increased the expression of SYP and PSD95, activated BDNF/TrkB/MAPK/ERK and PI3K/Akt signaling pathways, meanwhile decreased the expression of RhoA, ROCK and Snk, increased the levels of SPAR, and activated the BDNF/TrkB/cofilin signaling pathway. Taken together, our study indicated that xanthoceraside improved cognitive function and protected both synaptic morphology and dendritic spine in APP/PS1 transgenic mice, which might be related in part to its activation in the BDNF/TrkB pathway.

Stabilized Low-n Amyloid-β Oligomers Induce Robust Novel Object Recognition Deficits Associated with Inflammatory, Synaptic, and GABAergic Dysfunction in the Rat

BACKGROUND

With current treatments for Alzheimer's disease (AD) only providing temporary symptomatic benefits, disease modifying drugs are urgently required. This approach relies on improved understanding of the early pathophysiology of AD. A new hypothesis has emerged, in which early memory loss is considered a synapse failure caused by soluble amyloid-β oligomers (Aβo). These small soluble Aβo, which precede the formation of larger fibrillar assemblies, may be the main cause of early AD pathologies.

OBJECTIVE

The aim of the current study was to investigate the effect of acute administration of stabilized low-n amyloid-β1-42 oligomers (Aβo1-42) on cognitive, inflammatory, synaptic, and neuronal markers in the rat.

METHODS

Female and male Lister Hooded rats received acute intracerebroventricular (ICV) administration of either vehicle or 5 nmol of Aβo1-42 (10μL). Cognition was assessed in the novel object recognition (NOR) paradigm at different time points. Levels of inflammatory (IL-1β, IL-6, TNF-α), synaptic (PSD-95, SNAP-25), and neuronal (n-acetylaspartate, parvalbumin-positive cells) markers were investigated in different brain regions (prefrontal and frontal cortex, striatum, dorsal and ventral hippocampus).

RESULTS

Acute ICV administration of Aβo1-42 induced robust and enduring NOR deficits. These deficits were reversed by acute administration of donepezil and rolipram but not risperidone. Postmortem analysis revealed an increase in inflammatory markers, a decrease in synaptic markers and parvalbumin containing interneurons in the frontal cortex, with no evidence of widespread neuronal loss.

CONCLUSION

Taken together the results suggest that acute administration of soluble low-n Aβo may be a useful model to study the early mechanisms involved in AD and provide us with a platform for testing novel therapeutic approaches that target the early underlying synaptic pathology.

Ciliary neurotrophic factor is a key sex-specific regulator of depressive-like behavior in mice

Ciliary neurotrophic factor (CNTF) is produced by astrocytes and promotes neurogenesis and neuroprotection. Little is known about the role of CNTF in affective behavior. We investigated whether CNTF affects depressive- and anxiety-like behavior in adult mice as tested in the forced swim, sucrose preference and elevated-T maze tests. Female wild type CNTF+/+ mice more readily developed behavioral despair with increased immobility time and decreased latency to immobility in the forced swim test than male CNTF+/+ littermates. The lack of CNTF in CNTF-/- mice had an opposite effect on depressive-like behavior in female mice (reduced immobility time and increased sucrose preference) vs. male mice (increased immobility time). Female wildtype mice expressed more CNTF in the amygdala than male mice. Ovariectomy increased CNTF expression, as well as immobility time, which was significantly reduced in CNTF-/- mice, suggesting that CNTF mediates overiectomy-induced immobility time, possibly in the amygdala. Progesterone but not 17-β estradiol inhibited CNTF expression in cultured C6 astroglioma cells. Progesterone treatment also reduced CNTF expression in the amygdala and decreased immobility time in female CNTF+/+ but not in CNTF-/- mice. Castration did not alter CNTF expression in males nor their behavior. Lastly, there were no effects of CNTF on the elevated T-maze, a behavioral test of anxiety, suggesting that a different mechanism may underlie anxiety-like behavior. This study reveals a novel CNTF-mediated mechanism in stress-induced depressive-like behavior and points to opportunities for sex-specific treatments for depression, e.g. progesterone in females and CNTF-stimulating drugs in males.

[Dynamics of the cognitive sphere indicators and neurotrophic factors in the course of balneotherapy of dyscirculatory encephalopathy]

BACKGROUND

The natural factors of therapeutic significance play an important role in the rehabilitation of the patients suffering from chronic disorders of cerebral circulation since they are known to promote the development of the compensatory and adaptive processes. However, there is virtually no information in the relevant literature publications about the influence of balneotherapy on the dynamics of the cognitive sphere indicators and neurotrophic factors.

AIMS

The objective of the present study was to evaluate the effectiveness of balneotherapy as a component of the combined treatment of the patients presenting with discirculatory encephalopathy based on the investigations into dynamics of the neuropsychological status and the quantitative content of the neurotrophic factors in the peripheral blood, with special reference to the brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), in the patients receiving the balneotherapeutic treatment based at they at the 'Kluchi' health resort.

MATERIAL AND METHODS

A total of 72 patients presenting with the 1st and 2nd stages of chronic cerebral ischemia were examined (including 9 men and 63 women at the mean age of 62.2±2.1 years). They were given the health resort -based treatment during 14 days while staying at the 'Kluchi' resort located in the Perm region. The examination of all the patients included the psychometric testing and the determination of blood serum neurotrophic factors (BDNF and CNTF). The patients were allocated to three groups depending on the character of the prescribed treatment. The first group consisted of 29 subjects, who were given the conventional therapy (the alternation of hydrogen sulphide muds and baths number 7, daily massage of the neck-collar region in the combination with exercise therapy). The second group was comprised of 32 persons who received the standard course of chloride-sodium bromine baths number 7. The third group was composed of 11 persons suffering from chronic cerebral ischemia who received no balneo- or peloid therapy whatever.

RESULTS

The study has revealed the different stages of cognitive and emotional disorders combined with the initially reduced level of BDNF in the blood serum of the examined patients. The level of BDNF in the peripheral blood of the patients comprising the first group increased from 3.68±2.15 to 5.02±2.88 ng/ml after the course of balneotherapy. These values were significantly higher than before the treatment (p=0.000). In the patients of the second group, the level of situational and personal anxiety estimated with the use of the Spielberger-Khanin test decreased in association with the improvement in the cognitive sphere after they received the standard course of balneotherapy including the usual chloride-sodium bromine baths. Simultaneously, the level of BDNF in the peripheral blood of these patents increased from 4.00±2.3 to 5.39±2.44 ng/ml (p=0.02). The patients of the third group, who were given no treatment whatever displayed no statistically significant changes of the studied parameters.

CONCLUSION

The health resort-based treatment including the course of chloride-sodium bromine baths has a direct beneficial influence on the neuroreparative and neuroprotective functions in the patients presenting with chronic cerebral ischemia owing to the increase in the level of neurotrophic factors in the blood.

Stem cell therapy in Alzheimer's disease: possible benefits and limiting drawbacks

Alzheimer's disease (AD) is the sixth leading cause of death globally and the main reason for dementia in elderly people. AD is a long-term and progressive neurodegenerative disorder that steadily worsens memory and communicating skills eventually leads to a disabled person of performing simple daily tasks. Unfortunately, numerous clinical trials exploring new therapeutic drugs have encountered disappointing outcomes in terms of improved cognitive performance since they are not capable of halting or stimulating the regeneration of already-damaged neural cells, and merely provide symptomatic relief. Therefore, a deeper understanding of the mechanism of action of stem cell may contribute to the development of novel and effective therapies. The revolutionary discovery of stem cells has cast a new hope for the development of disease-modifying treatments for AD, in terms of their potency in the replenishment of lost cells via differentiating towards specific lineages, stimulating in situ neurogenesis, and delivering the therapeutic agents to the brain. Herein, firstly, we explore the pathophysiology of AD. Next, we summarize the most recent preclinical stem cell reports designed for AD treatment, their benefits and outcomes according to cell type. We briefly review relevant clinical trials and their potential clinical applications in order to find a unique solution to effectively relieve the patients' pain.

Mini-GAGR, an intranasally applied polysaccharide, activates the neuronal Nrf2-mediated antioxidant defense system

Oxidative stress triggers and exacerbates neurodegeneration in Alzheimer's disease (AD). Various antioxidants reduce oxidative stress, but these agents have little efficacy due to poor blood-brain barrier (BBB) permeability. Additionally, single-modal antioxidants are easily overwhelmed by global oxidative stress. Activating nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) and its downstream antioxidant system are considered very effective for reducing global oxidative stress. Thus far, only a few BBB-permeable agents activate the Nrf2-dependent antioxidant system. Here, we discovered a BBB-bypassing Nrf2-activating polysaccharide that may attenuate AD pathogenesis. Mini-GAGR, a 0.7-kDa cleavage product of low-acyl gellan gum, increased the levels and activities of Nrf2-dependent antioxidant enzymes, decreased reactive oxygen species (ROS) under oxidative stress in mouse cortical neurons, and robustly protected mitochondria from oxidative insults. Moreover, mini-GAGR increased the nuclear localization and transcriptional activity of Nrf2 similarly to known Nrf2 activators. Mechanistically, mini-GAGR increased the dissociation of Nrf2 from its inhibitor, Kelch-like ECH-associated protein 1 (Keap1), and induced phosphorylation and nuclear translocation of Nrf2 in a protein kinase C (PKC)- and fibroblast growth factor receptor (FGFR1)-dependent manner. Finally, 20-day intranasal treatment of 3xTg-AD mice with 100 nmol of mini-GAGR increased nuclear p-Nrf2 and growth-associated protein 43 (GAP43) levels in hippocampal neurons, reduced p-tau and β-amyloid (Aβ) peptide-stained neurons, and improved memory. The BBB-bypassing Nrf2-activating polysaccharide reported here may be effective in reducing oxidative stress and neurodegeneration in AD.

Cell-Surface Engineering for Advanced Cell Therapy

Stem cells opened great opportunity to overcome diseases that conventional therapy had only limited success. Use of scaffolds made from biomaterials not only helps handling of stem cells for delivery or transplantation but also supports enhanced cell survival. Likewise, cell encapsulation can provide stability for living animal cells even in a state of separateness. Although various chemical reactions were tried to encapsulate stolid microbial cells such as yeasts, a culture environment for the growth of animal cells allows only highly biocompatible reactions. Therefore, the animal cells were mostly encapsulated in hydrogels, which resulted in enhanced cell survival. Interestingly, major findings of chemistry on biological interfaces demonstrate that cell encapsulation in hydrogels have a further a competence for modulating cell characteristics that can go beyond just enhancing the cell survival. In this review, we present a comprehensive overview on the chemical reactions applied to hydrogel-based cell encapsulation and their effects on the characteristics and behavior of living animal cells.

Methamphetamine augment HIV-1 Tat mediated memory deficits by altering the expression of synaptic proteins and neurotrophic factors

Methamphetamine (METH) abuse is common among individuals infected with HIV-1 and has been shown to affect HIV replication and pathogenesis. These HIV-1 infected individuals also exhibit greater neuronal injury and higher cognitive decline. HIV-1 proteins, specifically gp120 and HIV-1 Tat, have been earlier shown to affect neurocognition. HIV-1 Tat, a viral protein released early during HIV-1 replication, contributes to HIV-associated neurotoxicity through various mechanisms including production of pro-inflammatory cytokines, reactive oxygen species and dysregulation of neuroplasticity. However, the combined effect of METH and HIV-1 Tat on neurocognition and its potential effect on neuroplasticity mechanisms remains largely unknown. Therefore, the present study was undertaken to investigate the combined effect of METH and HIV-1 Tat on behavior and on the expression of neuroplasticity markers by utilizing Doxycycline (DOX)-inducible HIV-1 Tat (1-86) transgenic mice. Expression of Tat in various brain regions of these mice was confirmed by RT-PCR. The mice were administered with an escalating dose of METH (0.1 mg/kg to 6 mg/kg, i.p) over a 7-day period, followed by 6 mg/kg, i.p METH twice a day for four weeks. After three weeks of METH administration, Y maze and Morris water maze assays were performed to determine the effect of Tat and METH on working and spatial memory, respectively. Compared with controls, working memory was significantly decreased in Tat mice that were administered METH. Moreover, significant deficits in spatial memory were also observed in Tat-Tg mice that were administered METH. A significant reduction in the protein expressions of synapsin 1, synaptophysin, Arg3.1, PSD-95, and BDNF in different brain regions were also observed. Expression levels of Calmodulin kinase II (CaMKII), a marker of synaptodendritic integrity, were also significantly decreased in HIV-1 Tat mice that were treated with METH. Together, this data suggests that METH enhances HIV-1 Tat-induced memory deficits by reducing the expression of pre- and postsynaptic proteins and neuroplasticity markers, thus providing novel insights into the molecular mechanisms behind neurocognitive impairments in HIV-infected amphetamine users.

Therapeutic effect of transmembrane TAT-tCNTF via Erk and Akt activation using in vitro and in vivo models of Alzheimer's disease

Suppressing Alzheimer's disease (AD) progression via its pathological characteristics, namely senile plaques and neurofibrillary tangles, is an efficient treatment approach. Numerous studies have indicated that ciliary neurotrophic factor (CNTF) not only promotes neuronal growth and maintains cell survival but also significantly reduces amyloid beta (Aβ) aggregation and deposition. In this study, transactivator of transcription (TAT) was linked to truncated ciliary neurotrophic factor (tCNTF) and expressed as a fusion protein, TAT-tCNTF, to overcome the transmembrane inability of CNTF. Accordingly, TAT-tCNTF was shown to automatically transport across biomembranes and enter cells mainly by macropinocytosis. Furthermore, TAT-tCNTF increased cell viability in hippocampal neurons treated with Aβ. After intracerebroventricular Aβ injection, mice exhibited amyloid deposits, which were significantly reduced after intraperitoneal TAT-tCNTF injection. Indeed, TAT-tCNTF significantly reduced Aβ-induced tau hyperphosphorylation, and yet barely affected amyloid precursor protein. Accordingly, it was possible to elucidate its potential pharmacological mechanism, with the working effect of TAT-tCNTF shown to be performed by specifically binding to its receptor, CNTFRα, and then activating the Extracellular regulated protein kinases (Erk) and Protein kinase B/Akt pathways exclusive of the Signal transducers and activators of transcription 3 (Stat3) pathway.

Recent Advances: Decoding Alzheimer's Disease With Stem Cells

Alzheimer’s disease (AD) is an irreversible neurodegenerative disorder that destroys cognitive functions. Recently, a number of high-profile clinical trials based on the amyloid cascade hypothesis have encountered disappointing results. The failure of these trials indicates the necessity for novel therapeutic strategies and disease models. In this review, we will describe how recent advances in stem cell technology have shed light on a novel treatment strategy and revolutionized the mechanistic investigation of AD pathogenesis. Current advances in promoting endogenous neurogenesis and transplanting exogenous stem cells from both bench research and clinical translation perspectives will be thoroughly summarized. In addition, reprogramming technology-based disease modeling, which has shown improved efficacy in recapitulating pathological features in human patients, will be discussed.

Brain STAT5 signaling modulates learning and memory formation

The signal transducer and activator of transcription 5 (STAT5) is a transcription factor recruited by numerous cytokines. STAT5 is important for several physiological functions, including body and tissue growth, mammary gland development, immune system and lipid metabolism. However, the role of STAT5 signaling for brain functions is still poorly investigated, especially regarding cognitive aspects. Therefore, the objective of the present study was to investigate whether brain STAT5 signaling modulates learning and memory formation. For this purpose, brain-specific STAT5 knockout (STAT5 KO) mice were studied in well-established memory tests. Initially, we confirmed a robust reduction in STAT5a and STAT5b mRNA levels in different brain structures of STAT5 KO mice. STAT5 KO mice showed no significant alterations in metabolism, growth, somatotropic axis and spontaneous locomotor activity. In contrast, brain-specific STAT5 ablation impaired learning and memory formation in the novel object recognition, Barnes maze and contextual fear conditioning tests. To unravel possible mechanisms that might underlie the memory deficits of STAT5 KO mice, we assessed neurogenesis in the hippocampus, but no significant differences were observed between groups. On the other hand, reduced insulin-like growth factor-1 (IGF-1) mRNA expression was found in the hippocampus and hypothalamus of STAT5 KO mice. These findings collectively indicate that brain STAT5 signaling is required to attain normal learning and memory. Therefore, STAT5 is an important downstream cellular mechanism shared by several cytokines to regulate cognitive functions.

Neurotrophic Factors: An Overview

The neurotrophins are a family of closely related proteins that were first identified as survival factors for sympathetic and sensory neurons and have since been shown to control a number of aspects of survival, development, and function of neurons in both the central and peripheral nervous systems. Limiting quantities of neurotrophins during development control the numbers of surviving neurons to ensure a match between neurons and the requirement for a suitable density of target innervation. Biological effects of each of the four mammalian neurotrophins are mediated through activation of one or more of the three members of the tropomyosin-related kinase (Trk) family of receptor tyrosine kinases (TrkA, TrkB, and TrkC). In addition, all neurotrophins activate the p75 neurotrophin receptor (p75^NTR), a member of the tumor necrosis factor receptor superfamily. Neurotrophin engagement of Trk receptors leads to activation of Ras, phosphatidylinositol 3-kinase, phospholipase C-γ1, and signaling pathways controlled through these proteins, including the mitogen-activated protein kinases. Neurotrophin availability is required into adulthood, where they control synaptic function and plasticity and sustain neuronal cell survival, morphology, and differentiation. This article will provide an overview of neurotrophin biology, their receptors, and signaling pathways.

Dietary arachidonic acid increases deleterious effects of amyloid-β oligomers on learning abilities and expression of AMPA receptors: putative role of the ACSL4-cPLA2 balance

Background

Polyunsaturated fatty acids play a crucial role in neuronal function, and the modification of these compounds in the brain could have an impact on neurodegenerative diseases such as Alzheimer’s disease. Despite the fact that arachidonic acid is the second foremost polyunsaturated fatty acid besides docosahexaenoic acid, its role and the regulation of its transfer and mobilization in the brain are poorly known.

Methods

Two groups of 39 adult male BALB/c mice were fed with an arachidonic acid-enriched diet or an oleic acid-enriched diet, respectively, for 12 weeks. After 10 weeks on the diet, mice received intracerebroventricular injections of either NaCl solution or amyloid-β peptide (Aβ) oligomers. Y-maze and Morris water maze tests were used to evaluate short- and long-term memory. At 12 weeks on the diet, mice were killed, and blood, liver, and brain samples were collected for lipid and protein analyses.

Results

We found that the administration of an arachidonic acid-enriched diet for 12 weeks induced short-term memory impairment and increased deleterious effects of Aβ oligomers on learning abilities. These cognitive alterations were associated with modifications of expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, postsynaptic density protein 95, and glial fibrillary acidic protein in mouse cortex or hippocampus by the arachidonic acid-enriched diet and Aβ oligomer administration. This diet also led to an imbalance between the main ω-6 fatty acids and the ω-3 fatty acids in favor of the first one in erythrocytes and the liver as well as in the hippocampal and cortical brain structures. In the cortex, the dietary arachidonic acid also induced an increase of arachidonic acid-containing phospholipid species in phosphatidylserine class, whereas intracerebroventricular injections modified several arachidonic acid- and docosahexaenoic acid-containing species in the four phospholipid classes. Finally, we observed that dietary arachidonic acid decreased the expression of the neuronal form of acyl-coenzyme A synthetase 4 in the hippocampus and increased the cytosolic phospholipase A₂ activation level in the cortices of the mice.

Conclusions

Dietary arachidonic acid could amplify Aβ oligomer neurotoxicity. Its consumption could constitute a risk factor for Alzheimer’s disease in humans and should be taken into account in future preventive strategies. Its deleterious effect on cognitive capacity could be linked to the balance between arachidonic acid-mobilizing enzymes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-017-0295-1) contains supplementary material, which is available to authorized users.

Structural and functional analyses of pyroglutamate-amyloid-β-specific antibodies as a basis for Alzheimer immunotherapy

Alzheimer disease is associated with deposition of the amyloidogenic peptide Aβ in the brain. Passive immunization using Aβ-specific antibodies has been demonstrated to reduce amyloid deposition both in vitro and in vivo Because N-terminally truncated pyroglutamate (pE)-modified Aβ species (AβpE3) exhibit enhanced aggregation potential and propensity to form toxic oligomers, they represent particularly attractive targets for antibody therapy. Here we present three separate monoclonal antibodies that specifically recognize AβpE3 with affinities of 1-10 nm and inhibit AβpE3 fibril formation in vitro. In vivo application of one of these resulted in improved memory in AβpE3 oligomer-treated mice. Crystal structures of Fab-AβpE3 complexes revealed two distinct binding modes for the peptide. Juxtaposition of pyroglutamate pE3 and the F4 side chain (the "pEF head") confers a pronounced bulky hydrophobic nature to the AβpE3 N terminus that might explain the enhanced aggregation properties of the modified peptide. The deep burial of the pEF head by two of the antibodies explains their high target specificity and low cross-reactivity, making them promising candidates for the development of clinical antibodies.

Improved Neuroprotection Provided by Drug Combination in Neurons Exposed to Cell-Derived Soluble Amyloid-β Peptide

Oligomeric amyloid-β (Aβ) peptide contributes to impaired synaptic connections and neurodegenerative processes, and as such, represents a primary therapeutic target for Alzheimer's disease (AD)-modifying approaches. However, the lack of efficacy of drugs that inhibit production of Aβ demonstrates the need for a better characterization of its toxic effects, both on synaptic and neuronal function. Here, we used conditioned medium obtained from recombinant HEK-AβPP cells expressing the human amyloid-β protein precursor (Aβ-CM), to investigate Aβ-induced neurotoxic and synaptotoxic effects. Characterization of Aβ-CM revealed that it contained picomolar amounts of cell-secreted Aβ in its soluble form. Incubation of primary cortical neurons with Aβ-CM led to significant decreases in synaptic protein levels as compared to controls. This effect was no longer observed in neurons incubated with conditioned medium obtained from HEK-AβPP cells grown in presence of the γ-secretase inhibitor, Semagacestat or LY450139 (LY-CM). However, neurotoxic and pro-apoptotic effects of Aβ-CM were only partially prevented using LY-CM, which could be explained by other deleterious compounds related to chronic oxidative stress that were released by HEK-AβPP cells. Indeed, full neuroprotection was observed in cells exposed to LY-CM by additional treatment with the antioxidant resveratrol, or with the pluripotent n-3 polyunsaturated fatty acid docosahexaenoic acid. Inhibition of Aβ production appeared necessary but insufficient to prevent neurodegenerative effects associated with AD due to other neurotoxic compounds that could exert additional deleterious effects on neuronal function and survival. Therefore, association of various types of protective agents needs to be considered when developing strategies for AD treatment.

Maintenance of membrane organization in the aging mouse brain as the determining factor for preventing receptor dysfunction and for improving response to anti-Alzheimer treatments

Although a major risk factor for Alzheimer's disease (AD), the "aging" parameter is not systematically considered in preclinical validation of anti-AD drugs. To explore how aging affects neuronal reactivity to anti-AD agents, the ciliary neurotrophic factor (CNTF)-associated pathway was chosen as a model. Comparison of the neuroprotective properties of CNTF in 6- and 18-month old mice revealed that CNTF resistance in the older animals is associated with the exclusion of the CNTF-receptor subunits from rafts and their subsequent dispersion to non-raft cortical membrane domains. This age-dependent membrane remodeling prevented both the formation of active CNTF-receptor complexes and the activation of prosurvival STAT3 and ERK1/2 pathways, demonstrating that age-altered membranes impaired the reactivity of potential therapeutic targets. CNTF-receptor distribution and CNTF signaling responses were improved in older mice receiving dietary docosahexaenoic acid, with CNTF-receptor functionality being similar to those of younger mice, pointing toward dietary intervention as a promising adjuvant strategy to maintain functional neuronal membranes, thus allowing the associated receptors to respond appropriately to anti-AD agents.

Subcutaneous implantation of microencapsulated cells overexpressing α-L-iduronidase for mucopolysaccharidosis type I treatment

Mucopolysaccharidosis type I (MPS I) is caused by a deficiency of α-L-iduronidase (IDUA), resulting in accumulation of glycosaminoglycans (GAG) in lysosomes. Microencapsulation of recombinant cells is a promising gene/cell therapy approach that could overcome the limitations of the current available treatments. In the present study we produced alginate-poly-L-lysine-alginate (APA) microcapsules containing recombinant cells overexpressing IDUA, which were implanted in the subcutaneous space of MPS I mice in order to evaluate their potential effect as a treatment for this disease. APA microcapsules enclosing genetically modified Baby Hamster Kidney cells overexpressing IDUA were produced and implanted in the subcutaneous space of 4-month-old MPS I mice (Idua ^-/-). Treatment was performed using two cell concentrations: 8.3 × 10⁷ and 8.3 × 10⁶ cells/mL. Untreated MPS I and normal mice were used as controls. Microcapsules were retrieved and analyzed after treatment. Increased IDUA in the liver, kidney and heart was detected 24 h postimplantation. After 120 days, higher IDUA activity was detected in the liver, kidney and heart, in both groups, whereas GAG accumulation was reduced only in the high cell concentration group. Microcapsules analysis showed blood vessels around them, as well as inflammatory cells and a fibrotic layer. Microencapsulated cells were able to ameliorate some aspects of the disease, indicating their potential as a treatment. To achieve better performance of the microcapsules, improvements such as the modulation of inflammatory response are suggested.

Conformal microcapsules encapsulating microcarrier-L02 cell complexes for treatment of acetaminophen-induced liver injury in rats

Conformal microcapsules encapsulating microcarrier-L02 cell complexes for treatment of acetaminophen-induced liver injury in rats.

Dendrobium alkaloids prevent Aβ25-35-induced neuronal and synaptic loss via promoting neurotrophic factors expression in mice

BACKGROUND

Neuronal and synaptic loss is the most important risk factor for cognitive impairment. Inhibiting neuronal apoptosis and preventing synaptic loss are promising therapeutic approaches for Alzheimer's disease (AD). In this study, we investigate the protective effects of Dendrobium alkaloids (DNLA), a Chinese medicinal herb extract, on β-amyloid peptide segment 25-35 (Aβ_25-35)-induced neuron and synaptic loss in mice.

METHOD

Aβ_25-35(10 µg) was injected into the bilateral ventricles of male mice followed by an oral administration of DNLA (40 mg/kg) for 19 days. The Morris water maze was used for evaluating the ability of spatial learning and memory function of mice. The morphological changes were examined via H&E staining and Nissl staining. TUNEL staining was used to check the neuronal apoptosis. The ultrastructure changes of neurons were observed under electron microscope. Western blot was used to evaluate the protein expression levels of ciliary neurotrophic factor (CNTF), glial cell line-derived neurotrophic factor (GDNF), and brain-derived neurotrophic factor (BDNF) in the hippocampus and cortex.

RESULTS

DNLA significantly attenuated Aβ_25-35-induced spatial learning and memory impairments in mice. DNLA prevented Aβ_25-35-induced neuronal loss in the hippocampus and cortex, increased the number of Nissl bodies, improved the ultrastructural injury of neurons and increased the number of synapses in neurons. Furthermore, DNLA increased the protein expression of neurotrophic factors BDNF, CNTF and GDNF in the hippocampus and cortex.

CONCLUSIONS

DNLA can prevent neuronal apoptosis and synaptic loss. This effect is mediated at least in part via increasing the expression of BDNF, GDNF and CNTF in the hippocampus and cortex; improving Aβ-induced spatial learning and memory impairment in mice.

One protein, multiple pathologies: multifaceted involvement of amyloid β in neurodegenerative disorders of the brain and retina

Accumulation of amyloid β (Aβ) and its aggregates in the ageing central nervous system is regarded synonymous to Alzheimer's disease (AD) pathology. Despite unquestionable advances in mechanistic and diagnostic aspects of the disease understanding, the primary cause of Aβ accumulation as well as its in vivo roles remains elusive; nonetheless, the majority of the efforts to address pathological mechanisms for therapeutic development are focused towards moderating Aβ accumulation in the brain. More recently, Aβ deposition has been identified in the eye and is linked with distinct age-related diseases including age-related macular degeneration, glaucoma as well as AD. Awareness of the Aβ accumulation in these markedly different degenerative disorders has led to an increasing body of work exploring overlapping mechanisms, a prospective biomarker role for Aβ and the potential to use retina as a model for brain related neurodegenerative disorders. Here, we present an integrated view of current understanding of the retinal Aβ deposition discussing the accumulation mechanisms, anticipated impacts and outlining ameliorative approaches that can be extrapolated to the retina for potential therapeutic benefits. Further longitudinal investigations in humans and animal models will determine retinal Aβ association as a potential pathognomonic, diagnostic or prognostic biomarker.

The role of growth factors as a therapeutic approach to demyelinating disease

A variety of growth factors are being explored as therapeutic agents relevant to the axonal and oligodendroglial deficits that occur as a result of demyelinating lesions such as are evident in Multiple Sclerosis (MS). This review focuses on five such proteins that are present in the lesion site and impact oligodendrocyte regeneration. It then presents approaches that are being exploited to manipulate the lesion environment affiliated with multiple neurodegenerative diseases and suggests that the utility of these approaches can extend to demyelination. Challenges are to further understand the roles of specific growth factors on a cellular and tissue level. Emerging technologies can then be employed to optimize the use of growth factors to ameliorate the deficits associated with demyelinating degenerative diseases.

Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer's disease

Alzheimer's disease (AD) is an incurable and debilitating chronic progressive neurodegenerative disorder which is the leading cause of dementia worldwide. AD is a heterogeneous and multifactorial disorder, histopathologically characterized by the presence of amyloid β (Aβ) plaques and neurofibrillary tangles composed of Aβ peptides and abnormally hyperphosphorylated tau protein, respectively. Independent of the various etiopathogenic mechanisms, neurodegeneration is a final common outcome of AD neuropathology. Synaptic loss is a better correlate of cognitive impairment in AD than Aβ or tau pathologies. Thus a highly promising therapeutic strategy for AD is to shift the balance from neurodegeneration to neuroregeneration and synaptic repair. Neurotrophic factors, by virtue of their neurogenic and neurotrophic activities, have potential for the treatment of AD. However, the clinical therapeutic usage of recombinant neurotrophic factors is limited because of the insurmountable hurdles of unfavorable pharmacokinetic properties, poor blood-brain barrier (BBB) permeability, and severe adverse effects. Neurotrophic factor small-molecule mimetics, in this context, represent a potential strategy to overcome these short comings, and have shown promise in preclinical studies. Neurotrophic factor small-molecule mimetics have been the focus of intense research in recent years for AD drug development. Here, we review the relevant literature regarding the therapeutic beneficial effect of neurotrophic factors in AD, and then discuss the recent status of research regarding the neurotrophic factor small-molecule mimetics as therapeutic candidates for AD. Lastly, we summarize the preclinical studies with a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic, Peptide 021 (P021). P021 is a neurogenic and neurotrophic compound which enhances dentate gyrus neurogenesis and memory processes via inhibiting leukemia inhibitory factor (LIF) signaling pathway and increasing brain-derived neurotrophic factor (BDNF) expression. It robustly inhibits tau abnormal hyperphosphorylation via increased BDNF mediated decrease in glycogen synthase kinase-3β (GSK-3β, major tau kinase) activity. P021 is a small molecular weight, BBB permeable compound with suitable pharmacokinetics for oral administration, and without adverse effects associated with native CNTF or BDNF molecule. P021 has shown beneficial therapeutic effect in several preclinical studies and has emerged as a highly promising compound for AD drug development.

BBB-Permeable, Neuroprotective, and Neurotrophic Polysaccharide, Midi-GAGR

An enormous amount of efforts have been poured to find an effective therapeutic agent for the treatment of neurodegenerative diseases including Alzheimer’s disease (AD). Among those, neurotrophic peptides that regenerate neuronal structures and increase neuron survival show a promise in slowing neurodegeneration. However, the short plasma half-life and poor blood-brain-barrier (BBB)-permeability of neurotrophic peptides limit their in vivo efficacy. Thus, an alternative neurotrophic agent that has longer plasma half-life and better BBB-permeability has been sought for. Based on the recent findings of neuroprotective polysaccharides, we searched for a BBB-permeable neuroprotective polysaccharide among natural polysaccharides that are approved for human use. Then, we discovered midi-GAGR, a BBB-permeable, long plasma half-life, strong neuroprotective and neurotrophic polysaccharide. Midi-GAGR is a 4.7kD cleavage product of low acyl gellan gum that is approved by FDA for human use. Midi-GAGR protected rodent cortical neurons not only from the pathological concentrations of co-/post-treated free reactive radicals and Aβ₄₂ peptide but also from activated microglial cells. Moreover, midi-GAGR showed a good neurotrophic effect; it enhanced neurite outgrowth and increased phosphorylated cAMP-responsive element binding protein (pCREB) in the nuclei of primary cortical neurons. Furthermore, intra-nasally administered midi-GAGR penetrated the BBB and exerted its neurotrophic effect inside the brain for 24 h after one-time administration. Midi-GAGR appears to activate fibroblast growth factor receptor 1 (FGFR1) and its downstream neurotrophic signaling pathway for neuroprotection and CREB activation. Additionally, 14-day intranasal administration of midi-GAGR not only increased neuronal activity markers but also decreased hyperphosphorylated tau, a precursor of neurofibrillary tangle, in the brains of the AD mouse model, 3xTg-AD. Taken together, midi-GAGR with good BBB-permeability, long plasma half-life, and strong neuroprotective and neurotrophic effects has a great therapeutic potential for the treatment of neurodegenerative diseases, especially AD.