The role of inflammation in Alzheimer's disease

Plasma Markers of Inflammation Linked to Clinical Progression and Decline During Preclinical AD

Objective

To examine the prospective association between blood biomarkers of immune functioning (i.e., innate immune activation, adaptive immunity, and inflammation) and subsequent cognitive decline and clinical progression to mild cognitive impairment (MCI) in cognitively normal individuals.

Methods

The BIOCARD study is an observational cohort study of N = 191 initially cognitively healthy participants (mean age 65.2 years). Blood plasma samples were assayed for markers of chronic inflammation (TNFR1, IL-6), adaptive immunity (CD25), and innate immune activation (CD14 and CD163). Participants were followed annually for ongoing clinical assessment and cognitive testing for up to 7.3 years. Primary study outcomes were progression to MCI and cognitive change over time, as measured by a global factor score encompassing multiple cognitive domains.

Results

Higher levels of plasma TNFR1 were associated with greater risk of progression from normal cognition to MCI (HR: 3.27; 95% confidence interval, CI: 1.27, 8.40). Elevated levels of TNFR1 were also associated with steeper rate of cognitive decline on follow-up but not with baseline cognitive performance. Baseline IL-6 levels and markers of innate and adaptive immune activation showed no relationship with MCI risk or cognitive decline.

Conclusion

Inflammation, mediated by TNF signaling, may play a selective role in the early phase of AD. Accordingly, plasma TNFR1 may facilitate improved prediction of disease progression for individuals in the preclinical stage of AD.

Diabetes drugs in the fight against Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia, particularly in old age subjects. Hyperinsulinemia and insulin resistance, which are known as pathophysiological features of Type 2 Diabetes Mellitus (T2DM), have also been demonstrated to have a significant impact on cognitive impairment. Studies have shown that an altered insulin pathway may interact with amyloid-β protein deposition and tau protein phosphorylation, both leading factors for AD development. Drugs used for T2DM treatment from insulin and metformin through dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists may represent a promising approach to fight AD. With this review from animal to human studies, we aim at responding to the reasons why drugs for diabetes may represent potential treatments for AD.

Redispersible Spray-Dried Powder Containing Nanoencapsulated Curcumin: the Drying Process Does Not Affect Neuroprotection In vitro

A redispersible spray-dried formulation containing curcumin-loaded, lipid-core nanocapsules (LNC-C) was developed for oral administration. The neuroprotective activity of curcumin after the spray-drying process was evaluated in vitro. The spray-dried powder (SD-LNC-C) was produced using a drying adjuvant composed of a blend of maltodextrin and L-leucine (90:10 w/w). Acceptable process yield (~ 70%) and drug content (6.5 ± 0.2 mg g^-1) were obtained. SD-LNC-C was formed by smooth, spherical-shaped particles, and confocal Raman analysis indicated the distribution of the LNC-C on the surface of the leucine/maltodextrin agglomerates. The surface of the agglomerates was formed by a combination of LNC-C and adjuvants, and laser diffraction showed that SD-LNC-C had adequate aqueous redispersion, with no loss of controlled drug release behaviour of LNC-C. The in vitro curcumin activity against the lipopolysaccharide (LPS)-induced proinflammatory response in organotypic hippocampal slice cultures was evaluated. Both formulations (LNC-C and SD-LNC-C) reduced TNF-α to similar levels. Therefore, neuroprotection of curcumin in vitro may be improved by nanoencapsulation followed by spray-drying, with no loss of this superior performance. Hence, the redispersible spray-dried powder proposed here represents a suitable approach for the development of innovative nanomedicines containing curcumin for the prevention/treatment of neurodegenerative diseases.

Cerebral transcriptome analysis reveals age-dependent progression of neuroinflammation in P301S mutant tau transgenic male mice

Aggregation of the microtubule-associated protein, tau, can lead to neurofibrillary tangle formation in neurons and glia which is the hallmark of tauopathy. The cellular damage induced by the formation of neurofibrillary tangles leads to neuroinflammation and consecutive neuronal death. However, detailed observation of transcriptomic changes under tauopathy together with the comparison of age-dependent progression of neuroinflammatory gene expressions mediated by tau overexpression is required. Employing RNA sequencing on PS19 transgenic mice that overexpress human mutant tau harboring the P301S mutation, we have examined the effects of age-dependent tau overexpression on transcriptomic changes of immune and inflammatory responses in the cerebral cortex. Compared to age-matched wild type control, P301S transgenic mice exhibit significant transcriptomic alterations. We have observed age-dependent neuroinflammatory gene expression changes in both wild type and P301S transgenic mice where tau overexpression further promoted the expression of neuroinflammatory genes in 10-month old P301S transgenic mice. Moreover, functional gene network analyses (gene ontology and pathway enrichment) and prospective target protein interactions predicted the potential involvement of multiple immune and inflammatory pathways that may contribute to tau-mediated neuronal pathology. Our current study on P301S transgenic mice model revealed for the first time, the differences of gene expression patterns in both early and late stage of tau pathology in cerebral cortex. Our analyses also revealed that tau overexpression alone induces multiple inflammatory and immune transcriptomic changes and may provide a roadmap to elucidate the targets of anti-inflammatory therapeutic strategy focused on tau pathology and related neurodegenerative diseases.

Oral diabetes medication and risk of dementia in elderly patients with type 2 diabetes

AIM

To examine the effect of oral diabetes medication on the risk of dementia in an elderly cohort with type 2 diabetes.

METHODS

This was a population-based cohort study using the Korean National Health Insurance claims data from 2002 to 2013. Elderly subjects (60 years of age or older) with and without type 2 diabetes were included; patients with new-onset type 2 diabetes were further divided into the oral diabetes medication group and no-medication group.

RESULTS

Among 278,290 patients with type 2 diabetes, 56,587 developed dementia (20.3%) over 11 years of follow-up. Type 2 diabetes was associated with a 1.69-fold increased risk of dementia (95% CI 1.66-1.72). Among patients with newly diagnosed type 2 diabetes, the risk of dementia was lower in the oral diabetes medication group than in the no-medication group (adjusted hazard ratio [aHR], 0.79; 95% CI 0.77-0.81). Lower risk of dementia was particularly noticeable in all of the combination therapy groups and especially lower in the combination therapy group treated with dipeptidyl peptidase 4 inhibitor (aHR 0.48, 95% CI 0.45-0.51).

CONCLUSION

Overall, the use of oral diabetes medication in type 2 diabetes patients significantly decreased the risk of dementia.

Hypoxia and Inflammation as a Consequence of β-Fibril Accumulation: A Perspective View for New Potential Therapeutic Targets

Amyloidoses are heterogeneous diseases that result from the deposition of toxic insoluble β-sheet fibrillar protein aggregates in different tissues. The cascade of molecular events leading to amyloidoses and to the related clinical manifestations is not completely understood. Nevertheless, it is known that tissue damage associated to this disease involves alteration of tissue architecture, interaction with cell surface receptors, inflammation elicited by the amyloid protein deposition, oxidative stress, and apoptosis. However, another important aspect to consider is that systemic protein massive deposition not only subverts tissue architecture but also determines a progressive cellular hypertrophy and dilation of the extracellular space enlarging the volume of the organ. Such an alteration increases the distance between cells and vessels with a drop in pO₂ that, in turn, causes both necrotic cell death and activation of the hypoxia transcription factor HIF-1α. Herewith, we propose the hypothesis that both cell death and hypoxia represent two important events for the pathogenesis of damage and progression of amyloidoses. In fact, molecules released by necrotic cells activate inflammatory cells from one side while binding to HIF-1α-dependent membrane receptors expressed on hypoxic parenchymal cells on the other side. This latter event generates a signaling cascade triggering NFκB activation and chronic inflammation. Finally, we also suggest that this scenario, once proved and detailed, might suggest important targets for new therapeutic interventions.

A core transcriptional signature of human microglia: Derivation and utility in describing region-dependent alterations associated with Alzheimer's disease

Growing recognition of the pivotal role microglia play in neurodegenerative and neuroinflammatory disorders has accentuated the need to characterize their function in health and disease. Studies in mouse have applied transcriptome-wide profiling of microglia to reveal key features of microglial ontogeny, functional profile, and phenotypic diversity. While similar, human microglia exhibit clear differences to their mouse counterparts, underlining the need to develop a better understanding of the human microglial profile. On examining published microglia gene signatures, limited consistency was observed between studies. Hence, we sought to derive a core microglia signature of the human central nervous system (CNS), through a comprehensive analysis of existing transcriptomic datasets. Nine datasets derived from cells and tissues, isolated from various regions of the CNS across numerous donors, were subjected independently to an unbiased correlation network analysis. From each dataset, a list of coexpressing genes corresponding to microglia was identified, with 249 genes highly conserved between them. This core signature included known microglial markers, and compared with other signatures provides a gene set specific to microglia in the context of the CNS. The utility of this signature was demonstrated by its use in detecting qualitative and quantitative region-specific alterations in aging and Alzheimer's disease. These analyses highlighted the reactive response of microglia in vulnerable brain regions such as the entorhinal cortex and hippocampus, additionally implicating pathways associated with disease progression. We believe this resource and the analyses described here, will support further investigations to the contribution of human microglia in CNS health and disease.

Metabolomic Analysis Identifies Alterations of Amino Acid Metabolome Signatures in the Postmortem Brain of Alzheimer's Disease

Despite significant advances in neuroscience research over the past several decades, the exact cause of AD has not yet fully understood. The metabolic hypothesis as well as the amyloid and tau hypotheses have been proposed to be associated with AD pathogenesis. In order to identify metabolome signatures from the postmortem brains of sporadic AD patients and control subjects, we performed ultra performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometer (UPLC-LTQ-Orbitrap-MS). Not only our study identified new metabolome signatures but also verified previously known metabolome profiles in the brain. Statistical modeling of the analytical data and validation of the structural assignments discovered metabolic biomarkers associated with the AD pathogenesis. Interestingly, hypotaurin, myo-inositol and oxo-proline levels were markedly elevated in AD while lutamate and N-acetyl-aspartate were decreased in the postmortem brain tissue of AD patients. In addition, neurosteroid level such as cortisol was significantly increased in AD. Together, our data indicate that impaired amino acid metabolism is associated with AD pathogenesis and the altered amino acid signatures can be useful diagnostic biomarkers of AD. Thus, modulation of amino acid metabolism may be a possible therapeutic approach to treat AD.

Trafficking of immune cells across the blood-brain barrier is modulated by neurofibrillary pathology in tauopathies

Tauopathies represent a heterogeneous group of neurodegenerative disorders characterized by abnormal deposition of the hyperphosphorylated microtubule-associated protein tau. Chronic neuroinflammation in tauopathies is driven by glial cells that potentially trigger the disruption of the blood-brain barrier (BBB). Pro-inflammatory signaling molecules such as cytokines, chemokines and adhesion molecules produced by glial cells, neurons and endothelial cells, in general, cooperate to determine the integrity of BBB by influencing vascular permeability, enhancing migration of immune cells and altering transport systems. We considered the effect of tau about vascular permeability of peripheral blood cells in vitro and in vivo using primary rat BBB model and transgenic rat model expressing misfolded truncated protein tau. Immunohistochemistry, electron microscopy and transcriptomic analysis were employed to characterize the structural and functional changes in BBB manifested by neurofibrillary pathology in a transgenic model. Our results show that misfolded protein tau ultimately modifies the endothelial properties of BBB, facilitating blood-to-brain cell transmigration. Our results suggest that the increased diapedesis of peripheral cells across the BBB, in response to tau protein, could be mediated by the increased expression of endothelial signaling molecules, namely ICAM-1, VCAM-1, and selectins. We suggest that the compensation of BBB in the diseased brain represents a crucial factor in neurodegeneration of human tauopathies.

STAT1 drives M1 microglia activation and neuroinflammation under hypoxia

Microglia are resident immune cells that act as the first active defence in the central nervous system. These cells constantly monitor the tissue microenvironment and rapidly react in response to hypoxia, infection and injuries. Hypoxia in the brain has been detected in several neurodegenerative disorders such as Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease and Huntington's disease. Hypoxic conditions activate microglia cells towards M1 phenotype resulting in oxidative stress and the release of pro-inflammatory cytokines. Recently, we have demonstrated that oxidative stress induces S-glutathionylation of the STAT1 and hyper-activates its signaling in microglia BV2 cells pointing out the importance of this transcription factor in neuroinflammation. In this paper we analyse the cellular mechanisms that drive M1 microglia activation in BV2 cells in response to hypoxia correlating it to STAT1 activation. The analysis of the molecular mechanism of STAT1 signaling reveals that hypoxia generates oxidative stress and induces both phosphorylation and S-glutathionylation of STAT1 that are responsible of its aberrant activation. The silencing of STAT1 protein expression counteracts hypoxia-M1 microglia phenotype suggesting the strong link between hypoxia-STAT1 and STAT1-microglia activation.

The Effect of Omega-3 and Omega-6 Polyunsaturated Fatty Acids on the Production of Cyclooxygenase and Lipoxygenase Metabolites by Human Umbilical Vein Endothelial Cells

Although the correlation between polyunsaturated fatty acids (PUFA) and the production of pro- and anti-inflammatory metabolites is well documented, little is known about the simultaneous effect of different PUFA on the production of cyclooxygenase and lipoxygenase metabolites. The present research examines the association between different omega-3 (ω-3) and omega-6 (ω-6) PUFA and the release of four cyclooxygenase and six lipoxygenase metabolites in cell medium by human umbilical vein endothelial cells (HUVEC). The different combinations of ω-3 and ω-6 PUFA were prepared according to a full 24 factorial design that enables studying not only the main effects but also the different interactions between fatty acids. In addition, interactions diagrams and principal component analysis were useful tools for interpreting higher order interactions. To the best of our knowledge, this is the first report addressing the combined effect of ω-3 and ω-6 PUFA on the signaling of prostaglandins, prostacyclins, leukotrienes and resolvins by HUVEC.

MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Aging is a complex and integrated gradual deterioration of cellular activities in specific organs of the body, which is associated with increased mortality. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, neurovascular disorders, and neurodegenerative diseases. There are nine tentative hallmarks of aging. In addition, several of these hallmarks are increasingly being associated with acute brain injury conditions. In this review, we consider the genes and their functional pathways involved in brain aging as a means of developing new strategies for therapies targeted to the neuropathological processes themselves, but also as targets for many age-related brain diseases. A single microRNA (miR), which is a short, non-coding RNA species, has the potential for targeting many genes simultaneously and, like practically all other cellular processes, genes associated with many features of brain aging and injury are regulated by miRs. We highlight how certain miRs can mediate deregulation of genes involved in neuroinflammation, acute neuronal injury and chronic neurodegenerative diseases. Finally, we review the recent progress in the development of effective strategies to block specific miR functions and discuss future approaches with the prediction that anti-miR drugs may soon be used in the clinic.

Toll-like receptors in the pathogenesis of neuroinflammation

Toll-like receptors (TLRs) are discovered as crucial pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs). Later studies showed their involvement in the recognition of various damage/danger-associated molecular patterns (DAMPs) generated by host itself. Thus, TLRs are capable of recognizing wide-array of patterns/molecules derived from pathogens and host as well and initiating a proinflammatory immune response through the activation of NF-κB and other transcription factors causing synthesis of proinflammatory molecules. The process of neuroinflammation is seen under both sterile and infectious inflammatory diseases of the central nervous system (CNS) and may lead to the development of neurodegeneration. The present article is designed to highlight the importance of TLRs in the pathogenesis of neuroinflammation under diverse conditions. TLRs are expressed by various immune cells present in CNS along with neurons. However out of thirteen TLRs described in mammals, some are present and active in these cells, while some are absent and are described in detail in main text. The role of various immune cells present in the brain and their role in the pathogenesis of neuroinflammation depending on the type of TLR expressed is described. Thereafter the role of TLRs in bacterial meningitis, viral encephalitis, stroke, Alzheimer's disease (AD), Parkinson's disease (PD), and autoimmune disease including multiple sclerosis (MS) is described. The article is designed for both neuroscientists needing information regarding TLRs in neuroinflammation and TLR biologists or immunologists interested in neuroinflammation.

Activation of microglia and astrocytes: a roadway to neuroinflammation and Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease that is of high importance to the neuroscience world, yet the complex pathogenicity is not fully understood. Inflammation is usually observed in AD and could implicate both beneficial or detrimental effects depending on the severity of the disease. During initial AD pathology, microglia and astrocyte activation is beneficial since they are involved in amyloid-beta clearance. However, with the progression of the disease, activated microglia elicit detrimental effects by the overexpression of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) bringing forth neurodegeneration in the surrounding brain regions. This results in decline in Aβ clearance by microglia; Aβ accumulation thus increases in the brain resulting in neuroinflammation. Thus, Aβ accumulation is the effect of increased release of pro-inflammatory molecules. Reactive astrocytes acquire gain of toxic function and exhibits neurotoxic effects with loss of neurotrophic functions. Astrocyte dysfunctioning results in increased release of cytokines and inflammatory mediators, neurodegeneration, decreased glutamate uptake, loss of neuronal synapses, and ultimately cognitive deficits in AD. We discuss the role of intracellular signaling pathways in the inflammatory responses produced by astrocytes and microglial activation, including the glycogen synthase kinase-3β, nuclear factor kappa B cascade, mitogen-activated protein kinase pathways and c-Jun N-terminal kinase. In this review, we describe the role of neuroinflammation in the chronicity of AD pathogenesis and an overview of the recent research towards the development of new therapies to treat this disorder.

Tea polyphenols as multi-target therapeutics for Alzheimer's disease: An in silico study

Alzheimer's disease (AD) is the most common progressive neurodegenerative disease characterized by cognitive decline, dementia, and in later stages complete loss of feelings, sensation and death. The global prevalence of the disease is on the rise, and it affects 35-40% of the population above 80 years. The pathological hallmarks of the disease include extra-neuronal deposition of amyloid-β (Aβ) as plaques and intra-neuronal hyperphosphorylated tau protein as neurofibrillary tangles, which cause neurodegeneration and cerebral atrophy. Aβ deposition is catalyzed by β-secretase and γ-secretase, while tau hyperphosphorylation is catalyzed by glycogen synthase kinase - 3β (GSK-3β). With neurodegeneration, the level of the neurotransmitter acetylcholine (ACh), as well as acetylcholinesterase (AChE), decreases in the synaptic cleft, called cholinergic deficiency. This leads to the cardinal behavioural abnormalities of AD, which is referred to as cholinergic hypothesis of AD. The other enzyme which degrades ACh is the butyrylcholinesterase (BuChE). Thus, current treatment options of AD include symptomatic treatment to elevate the levels of ACh by inhibiting AChE. However, the currently used drugs cause several side effects, and the quest for novel drugs remains an interesting and essential venture. Since the disease has multiple pathophysiologies, there is an unrelenting need to develop novel drugs and lead molecules capable of inhibiting multiple pathways. The present study hypothesizes use of tea polyphenols against the key drug targets of AD, viz. β-Secretase, γ-Secretase, GSK-3β, AChE and BuChE. The hypothesis has been validated using molecular docking tools. The result indicates that the polyphenols may potentially inhibit these enzymes, similar to their known inhibitors. Thus, the findings are of immense significance in the therapeutic interventions of AD, using tea polyphenols as exciting multi-target drugs.

A critical review on grape polyphenols for neuroprotection: Strategies to enhance bioefficacy

The aging of populations worldwide is driving greater demands for dietary polyphenols which have been recognized as promising prophylactic and/or therapeutic agents in the context of neurodegeneration, and are ubiquitously present in plant-based diets. In particular, grape-derived products encompass a wide array of phenolic compounds purported with multiple health benefits including neuroprotective efficacy. Despite the increasing preclinical and clinical evidence demonstrating high potential of grape polyphenol (GPP)-rich botanicals in preventing and attenuating diverse neurodegenerative disorders, the limited bioavailability of GPPs, especially in the brain, generates questions as to their applications and effectiveness in neuroprotection. To address this issue, significant research efforts have been made to enhance oral bioavailability of GPPs via application of novel strategies. This review highlights some critical issues related to the bioavailability and neuroprotective efficacy of GPPs and GPP-rich botanicals. The representative bioavailability-enhancing strategies are critically reviewed to provide practical solutions for augmenting the bioefficacy of GPP-rich botanicals. Synergistic applications of encapsulation techniques (for physiochemical protection and bypassing xenobiotic metabolism) and dietary intervention strategies involving modulation of gut microbiota (for generating more bioavailable phenolic metabolites) appear promising, and may substantially enhance the bioefficacy, especially the neuroprotective efficacy, of orally consumed GPPs.

The Retina as a Window or Mirror of the Brain Changes Detected in Alzheimer's Disease: Critical Aspects to Unravel

Alzheimer's disease is the most frequent cause of dementia worldwide, representing a global health challenge, with a massive impact on the quality of life of Alzheimer's disease patients and their relatives. The diagnosis of Alzheimer's disease constitutes a real challenge, because the symptoms manifest years after the first degenerative changes occurring in the brain and the diagnosis is based on invasive and/or expensive techniques. Therefore, there is an urgent need to identify new reliable biomarkers to detect Alzheimer's disease at an early stage. Taking into account the evidence for visual deficits in Alzheimer's disease patients, sometimes even before the appearance of the first disease symptoms, and that the retina is an extension of the brain, the concept of the retina as a window to look into the brain or a mirror of the brain has received increasing interest in recent years. However, only a few studies have assessed the changes occurring in the retina and the brain at the same time points. Unlike previous reviews on this subject, which are mainly focused on brain changes, we organized this review by comprehensively summarizing findings related with structural, functional, cellular, and molecular parameters in the retina reported in both Alzheimer's disease patients and animal models. Moreover, we separated the studies that assessed only the retina, and those that assessed both the retina and brain, which are few but allow establishing correlations between the retina and brain. This review also highlights some inconsistent results in the literature as well as relevant missing gaps in this field.

A pilot study on the effect of lactoferrin on Alzheimer's disease pathological sequelae: Impact of the p-Akt/PTEN pathway

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases in which the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (PKB or Akt) pathway is deregulated in response to phosphatase and tensin homolog (PTEN) overexpression. Lactoferrin (LF), a multifunctional iron-binding glycoprotein, is involved in AD pathology; however, direct evidence of its impact upon AD remains unclear. To elucidate LF's role in AD, the possible protective mechanism post-LF administration for 3 months was investigated in AD patients by observing changes in the p-Akt/PTEN pathway. AD patients showed decreased serum acetylcholine (ACh), serotonin (5-HT), antioxidant and anti-inflammatory markers, and decreased expression of Akt in peripheral blood lymphocytes (PBL), as well as PI3K, and p-Akt levels in PBL lysate; all these parameters were significantly improved after daily LF administration for 3 months. Similarly, elevated serum amyloid β (Aβ) 42, cholesterol, oxidative stress markers, IL-6, heat shock protein (HSP) 90, caspase-3, and p-tau, as well as increased expression of tau, MAPK1 and PTEN in AD patients, were significantly reduced upon LF intake. Improvement in the aforementioned AD surrogate markers post-LF treatment was reflected in enhanced cognitive function assessed by the Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment Scale-Cognitive Subscale 11-item (ADAS-COG 11) questionnaires as clinical endpoints. These results provide a basis for a possible protective mechanism of LF in AD through its ability to alleviate the AD pathological cascade and cognitive decline via modulation of the p-Akt/PTEN pathway, which affects the key players of inflammation and oxidative stress that are involved in AD pathology.

How stress mediators can cumulatively contribute to Alzheimer's disease An allostatic load approach

Allostatic load is defined as the frequent activation of the neuroendocrine, immunological, metabolic and cardiovascular systems, which makes individuals more susceptible to stress-related health problems. According to this model, physiological dysregulations start to emerge decades before diseases manifest. Consequently, stress research has shifted its attention to anticipating the degree of this dysregulation to better understand the impact of stress hormones and other biomarkers on disease progression. In view of the growing number of studies that demonstrate the influence of modifiable risk factors on cognitive decline, in addition to the effects of chronic stress mediators, the objective of the present review was to present an overview of the development of cognitive changes based on studies on stress and its mediators.

Neuroprotective Effects of Spinosin on Recovery of Learning and Memory in a Mouse Model of Alzheimer's Disease

Previous studies have shown that spinosin was implicated in the modulation of sedation and hypnosis, while its effects on learning and memory deficits were rarely reported. The aim of this study is to investigate the effects of spinosin on the improvement of cognitive impairment in model mice with Alzheimer’s disease (AD) induced by Aβ_1–42 and determine the underlying mechanism. Spontaneous locomotion assessment and Morris water maze test were performed to investigate the impact of spinosin on behavioral activities, and the pathological changes were assayed by biochemical analyses and histological assay. After 7 days of intracerebroventricular (ICV) administration of spinosin (100 µg/kg/day), the cognitive impairment of mice induced by Aβ_1–42 was significantly attenuated. Moreover, spinosin treatment effectively decreased the level of malondialdehyde (MDA) and Aβ_1–42 accumulation in hippocampus. Aβ_1–42 induced alterations in the expression of brain derived neurotrophic factor (BDNF) and B-cell lymphoma-2 (Bcl-2), as well as inflammatory response in brain were also reversed by spinosin treatment. These results indicated that the ameliorating effect of spinosin on cognitive impairment might be mediated through the regulation of oxidative stress, inflammatory process, apoptotic program and neurotrophic factor expression, suggesting that spinosin might be beneficial to treat learning and memory deficits in patients with AD via multi-targets.

Advances in developing novel therapeutic strategies for Alzheimer's disease

Alzheimer's Disease (AD), the most prevalent neurodegenerative disease of aging, affects one in eight older Americans. Nearly all drug treatments tested for AD today have failed to show any efficacy. There is a great need for therapies to prevent and/or slow the progression of AD. The major challenge in AD drug development is lack of clarity about the mechanisms underlying AD pathogenesis and pathophysiology. Several studies support the notion that AD is a multifactorial disease. While there is abundant evidence that amyloid plays a role in AD pathogenesis, other mechanisms have been implicated in AD such as tangle formation and spread, dysregulated protein degradation pathways, neuroinflammation, and loss of support by neurotrophic factors. Therefore, current paradigms of AD drug design have been shifted from single target approach (primarily amyloid-centric) to developing drugs targeted at multiple disease aspects, and from treating AD at later stages of disease progression to focusing on preventive strategies at early stages of disease development. Here, we summarize current strategies and new trends of AD drug development, including pre-clinical and clinical trials that target different aspects of disease (mechanism-based versus non-mechanism based, e.g. symptomatic treatments, lifestyle modifications and risk factor management).

In-vitro evaluation studies of 7-chloro-4-aminoquinoline Schiff bases and their copper complexes as cholinesterase inhibitors

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders. Aggregation of amyloid-β peptide into extracellular plaques with incorporation of metal ions, such as Cu²⁺, and reduction of the neurotransmitter acetylcholine levels are among the factors associated to the AD brain. Hence, a series of 7-chloro-4-aminoquinoline Schiff bases (HLa-e) were synthesized and their cytotoxicity and anti-cholinesterase activity, assessed for Alzheimer's disease. The intrinsic relationship between Cu²⁺ and the amyloidogenic plaques encouraged us to investigate the chelating ability of HLa-e. Dimeric tetracationic compounds, [Cu₂(N^HLa-e)₄]Cl₄, containing quinoline protonated ligands were isolated from the reactions with CuCl₂·2H₂O and fully characterized in the solid state, including an X ray diffraction study, whereas EPR data showed that the complexes exist as monomers in DMSO solution. The inhibitory activity of all compounds was evaluated by Ellman's spectrophotometric method in acetylcholinesterase (AChE) from Electrophorus electricus and butyrylcholinesterase (BChE) from equine serum. HLa-e and [Cu(N^HLd)₂]Cl₂ were selective for AChE (IC₅₀ = 4.61-9.31 μM) and were not neurotoxic in primary brain cultures. Docking and molecular dynamics studies of HLa-e inside AChE were performed and the results suggested that these compounds are able to bind inside AChE similarly to other AChE inhibitors, such as donepezil. Studies of the affinity of HLd for Cu²⁺ in DMSO/HEPES at pH 6.6 and pH 7.4 in μM concentrations showed formation of analogous 1:2 Cu²⁺/ligand complexes, which may suggest that in the AD-affected brain HLd may scavenge Cu²⁺ and the complex, also inhibit AChE.

The human olfactory cleft mucus proteome and its age-related changes

Age-related decreases in olfactory sensitivity are often accompanied by a decrease in the quality of life. However, the molecular mechanisms underlying these changes are not well described. Inhaled substances including odorants are detected by sensory neurons in the olfactory cleft covered with a layer of mucus. This olfactory mucus is the first molecular machinery responsible for tissue protection and for detection of environmental odorants. Yet, little is known about the molecular identities of the actors because of the lack of information on the mucus proteome and its age-related changes. Here, we sampled human mucus from different nasal locations and from young and elderly subjects. The composition of the mucus was extensively analyzed by shotgun proteomic analysis for a vast array of proteins. We also explored correlations between the levels of each mucus proteins with the olfactory sensitivity of subjects. This analysis revealed previously unrecognized proteins with potentially important functions in olfaction. Taken together, this report describes the most comprehensive catalogue of the nasal mucus proteins to date, their positional and age-related differences, and candidate proteins associated with olfaction. This catalogue will provide fundamental information useful for future studies, such as identification of olfactory auxiliary proteins, causes of age-related declines in olfaction, and biomarkers for neurodegenerative disorders.

Changing Paradigm from one Target one Ligand Towards Multi-target Directed Ligand Design for Key Drug Targets of Alzheimer Disease: An Important Role of In Silico Methods in Multi-target Directed Ligands Design

Alzheimer disease (AD) is now considered as a multifactorial neurodegenerative disorder and rapidly increasing to an alarming situation and causing higher death rate. One target one ligand hypothesis does not provide complete solution of AD due to multifactorial nature of the disease and one target one drug fails to provide better treatment against AD. Moreo-ver, currently available treatments are limited and most of the upcoming treatments under clinical trials are based on modulat-ing single target. So, the current AD drug discovery research is shifting towards a new approach for a better solution that simultaneously modulates more than one targets in the neurodegenerative cascade. This can be achieved by network pharma-cology, multi-modal therapies, multifaceted, and/or the more recently proposed term “multi-targeted designed drugs”. Drug discovery project is a tedious, costly and long-term project. Moreover, multi-target AD drug discovery added extra challeng-es such as the good binding affinity of ligands for multiple targets, optimal ADME/T properties, no/less off-target side effect and crossing of the blood-brain barrier. These hurdles may be addressed by insilico methods for an efficient solution in less time and cost as computational methods successfully applied to single target drug discovery project. Here, we are summariz-ing some of the most prominent and computationally explored single targets against AD and further, we discussed a success-ful example of dual or multiple inhibitors for same targets. Moreover, we focused on ligand and structure-based computa-tional approach to design MTDL against AD. However, it is not an easy task to balance dual activity in a single molecule but computational approach such as virtual screening docking, QSAR, simulation and free energy is useful in future MTDLs drug discovery alone or in combination with a fragment-based method. However, rational and logical implementations of computational drug designing methods are capable of assisting AD drug discovery and play an important role in optimizing multi-target drug discovery.

Distinguishing normal brain aging from the development of Alzheimer's disease: inflammation, insulin signaling and cognition

As populations age, prevalence of Alzheimer's disease (AD) is rising. Over 100 years of research has provided valuable insights into the pathophysiology of the disease, for which age is the principal risk factor. However, in recent years, a multitude of clinical trial failures has led to pharmaceutical corporations becoming more and more unwilling to support drug development in AD. It is possible that dependence on the amyloid cascade hypothesis as a guide for preclinical research and drug discovery is part of the problem. Accumulating evidence suggests that amyloid plaques and tau tangles are evident in non-demented individuals and that reducing or clearing these lesions does not always result in clinical improvement. Normal aging is associated with pathologies and cognitive decline that are similar to those observed in AD, making differentiation of AD-related cognitive decline and neuropathology challenging. In this mini-review, we discuss the difficulties with discerning normal, age-related cognitive decline with that related to AD. We also discuss some neuropathological features of AD and aging, including amyloid and tau pathology, synapse loss, inflammation and insulin signaling in the brain, with a view to highlighting cognitive or neuropathological markers that distinguish AD from normal aging. It is hoped that this review will help to bolster future preclinical research and support the development of clinical tools and therapeutics for AD.

Isolation and identification of peptides from simulated gastrointestinal digestion of preserved egg white and their anti-inflammatory activity in TNF-α-induced Caco-2 cells

Simulated gastrointestinal digestion of preserved egg white (SGD-PEW) exerts anti-inflammatory effects on Caco-2 cells and a mouse model of DSS-induced colitis. Here, we aimed to separate peptides derived from SGD-PEW and evaluate their anti-inflammatory effects using an in vitro inflammatory model. Six peptides were isolated and identified. DEDTQAMPFR (DR-10), DEDTQAMPF (DF-9), MLGATSL (ML-7) and MSYSAGF (MF-7) significantly inhibited IL-8 secretion and markedly decreased gene expression, including TNF-α, IL-8, IL-6, IL-1β and IL-12 and promoted IL-10 gene expression in Caco-2 cells. DR-10, DF-9, ML-7 and MF-7 significantly inhibited the phosphorylation of JNK. In the meantime, DR-10 and DF-9 significantly reduced the phosphorylation of IκB and p38. These results indicated that ML-7 and MF-7 exerted their anti-inflammatory activity through the MAPK signaling pathway in TNF-α-induced Caco-2 cells. Whereas, DR-10 and DF-9 inhibited the NF-κB and MAPK signaling pathways. The results suggested that DR-10, DF-9, ML-7 and MF-7 derived from SGD-PEW may be a new type of prophylactic food for the treatment of inflammation.

Inflammation as a central mechanism in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is characterized by cognitive decline and the presence of two core pathologies, amyloid β plaques and neurofibrillary tangles. Over the last decade, the presence of a sustained immune response in the brain has emerged as a third core pathology in AD. The sustained activation of the brain's resident macrophages (microglia) and other immune cells has been demonstrated to exacerbate both amyloid and tau pathology and may serve as a link in the pathogenesis of the disorder. In the following review, we provide an overview of inflammation in AD and a detailed coverage of a number of microglia-related signaling mechanisms that have been implicated in AD. Additional information on microglia signaling and a number of cytokines in AD are also reviewed. We also review the potential connection of risk factors for AD and how they may be related to inflammatory mechanisms.

Thymoquinone increases the expression of neuroprotective proteins while decreasing the expression of pro-inflammatory cytokines and the gene expression NFκB pathway signaling targets in LPS/IFNγ -activated BV-2 microglia cells

Neuroinflammation and microglial activation are pathological markers of a number of central nervous system (CNS) diseases. Chronic activation of microglia induces the release of excessive amounts of reactive oxygen species (ROS) and pro-inflammatory cytokines. Additionally, chronic microglial activation has been implicated in several neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Thymoquinone (TQ) has been identified as one of the major active components of the natural product Nigella sativa seed oil. TQ has been shown to exhibit anti-inflammatory, anti-oxidative, and neuroprotective effects. In this study, lipopolysaccharide (LPS) and interferon gamma (IFNγ) activated BV-2 microglial cells were treated with TQ (12.5 μM for 24 h). We performed quantitative proteomic analysis using Orbitrap/Q-Exactive Proteomic LC-MS/MS (Liquid chromatography-mass spectrometry) to globally assess changes in protein expression between the treatment groups. Furthermore, we evaluated the ability of TQ to suppress the inflammatory response using ELISArray™ for Inflammatory Cytokines. We also assessed TQ's effect on the gene expression of NFκB signaling targets by profiling 84 key genes via real-time reverse transcription (RT2) PCR array. Our results indicated that TQ treatment of LPS/IFNγ-activated microglial cells significantly increased the expression of 4 antioxidant, neuroprotective proteins: glutaredoxin-3 (21 fold; p < 0.001), biliverdin reductase A (15 fold; p < 0.0001), 3-mercaptopyruvate sulfurtransferase (11 fold; p < 0.01), and mitochondrial lon protease (>8 fold; p < 0.001) compared to the untreated, activated cells. Furthermore, TQ treatment significantly (P < 0.0001) reduced the expression of inflammatory cytokines, IL-2 = 38%, IL-4 = 19%, IL-6 = 83%, IL-10 = 237%, and IL-17a = 29%, in the activated microglia compared to the untreated, activated which expression levels were significantly elevated compared to the control microglia: IL-2 = 127%, IL-4 = 151%, IL-6 = 670%, IL-10 = 133%, IL-17a = 127%. Upon assessing the gene expression of NFκB signaling targets, this study also demonstrated that TQ treatment of activated microglia resulted in >7 fold down-regulation of several NFκB signaling targets genes, including interleukin 6 (IL6), complement factor B (CFB), chemokine (CC motif) ligand 3 (CXCL3), chemokine (CC) motif ligand 5 (CCL5) compared to the untreated, activated microglia. This modulation in gene expression counteracts the >10-fold upregulation of these same genes observed in the activated microglia compared to the controls. Our results show that TQ treatment of LPS/IFNγ-activated BV-2 microglial cells induce a significant increase in expression of neuroprotective proteins, a significant decrease in expression inflammatory cytokines, and a decrease in the expression of signaling target genes of the NFκB pathway. Our findings are the first to show that TQ treatment increased the expression of these neuroprotective proteins (biliverdin reductase-A, 3-mercaptopyruvate sulfurtransferase, glutaredoxin-3, and mitochondrial lon protease) in the activated BV-2 microglial cells. Additionally, our results indicate that TQ treatment decreased the activation of the NFκB signaling pathway, which plays a key role in neuroinflammation. In conclusion, our results demonstrate that TQ treatment reduces the inflammatory response and modulates the expression of specific proteins and genes and hence potentially reduce neuroinflammation and neurodegeneration driven by microglial activation.

Cellular Receptors of Amyloid β Oligomers (AβOs) in Alzheimer's Disease

It is estimated that Alzheimer’s disease (AD) affects tens of millions of people, comprising not only suffering patients, but also their relatives and caregivers. AD is one of age-related neurodegenerative diseases (NDs) characterized by progressive synaptic damage and neuronal loss, which result in gradual cognitive impairment leading to dementia. The cause of AD remains still unresolved, despite being studied for more than a century. The hallmark pathological features of this disease are senile plaques within patients’ brain composed of amyloid beta (Aβ) and neurofibrillary tangles (NFTs) of Tau protein. However, the roles of Aβ and Tau in AD pathology are being questioned and other causes of AD are postulated. One of the most interesting theories proposed is the causative role of amyloid β oligomers (AβOs) aggregation in the pathogenesis of AD. Moreover, binding of AβOs to cell membranes is probably mediated by certain proteins on the neuronal cell surface acting as AβO receptors. The aim of our paper is to describe alternative hypotheses of AD etiology, including genetic alterations and the role of misfolded proteins, especially Aβ oligomers, in Alzheimer’s disease. Furthermore, in this review we present various putative cellular AβO receptors related to toxic activity of oligomers.

Effects of inflammation on social processes and implications for health

Although at first glance inflammation and social behavior may appear unrelated, research points to an important role for inflammation in shaping social processes. This review summarizes findings in this field, specifically highlighting work that provides support for the idea that inflammation can lead to (1) increases in sensitivity to negative, threatening social experiences and (2) increases in sensitivity to positive, socially rewarding experiences. These diverging sensitivities in response to inflammation may depend on context and be adaptive for recuperation and recovery from illness. This review also discusses the implications of these findings for health and future research, including implications for depression, loneliness, and inflammatory disorders.

Intermittent streptozotocin administration induces behavioral and pathological features relevant to Alzheimer's disease and vascular dementia

RATIONALE

Diabetes mellitus (DM) is a major risk factor for Alzheimer's disease and vascular dementia. Few animal models exist that focus on the metabolic contributions to dementia onset and progression. Thus, there is strong scientific rationale to explore the effects of streptozotocin (STZ), a diabetogenic compound, on vascular and inflammatory changes within the brain.

OBJECTIVE AND METHODS

The present study was designed to evaluate the effect of staggered, low-dose administration of STZ on behavioral and cognitive deficits, neuroinflammation, tau pathology, and histopathological alterations related to dementia.

RESULTS

Staggered administration (Days 1, 2, 3, 14, 15) of streptozotocin (40 mg/kg/mL) induced a diabetic-like state in mice, resulting in sustained hyperglycemia. STZ-treated animals displayed memory deficits in the novel object recognition task as well as increased tau phosphorylation and increased neuroinflammation. Additionally, STZ led to altered insulin signaling, exhibited by decreased plasma insulin and decreased levels of insulin degrading enzyme and pAKT within the hippocampus.

CONCLUSIONS

STZ-treated animals exhibit cognitive deficits and histopathological changes seen in dementia. This model of dementia warrants continued investigation to better understand the role that DM plays in dementia-related alterations.

Blood Ammonia as a Possible Etiological Agent for Alzheimer's Disease

Alzheimer’s disease (AD), characterized by cognitive decline and devastating neurodegeneration, is the most common age-related dementia. Since AD is a typical example of a complex disease that is affected by various genetic and environmental factors, various factors could be involved in preventing and/or treating AD. Extracellular accumulation of beta-amyloid peptide (Aβ) and intracellular accumulation of tau undeniably play essential roles in the etiology of AD. However, interestingly enough, medications targeting Aβ or tau all failed and the only clinically efficient medications for AD are drugs targeting the cholinergic pathway. Also, a very intriguing discovery in AD is that the Mediterranean diet (MeDi), containing an unusually large quantity of Lactobacilli, is very effective in preventing AD. Based on recently emerging findings, it is our opinion that the reduction of blood ammonia levels by Lactobacilli in MeDi is the therapeutic agent of MeDi for AD. The recent evidence of Lactobacilli lowering blood ammonia level not only provides a link between AD and MeDi but also provides a foundation of pharmabiotics for hyperammonemia as well as various neurological diseases.

Transplantation of Human Menstrual Blood-Derived Mesenchymal Stem Cells Alleviates Alzheimer's Disease-Like Pathology in APP/PS1 Transgenic Mice

Extracellular β-amyloid (Aβ) plaques and neurofibrillary tangles (NFTs) are the pathological hallmarks of Alzheimer’s disease (AD). Mesenchymal stem cells (MSCs) have shown therapeutic efficacy in many neurodegenerative diseases, including AD. Human menstrual blood-derived stem cells (MenSCs) are a novel source of MSCs advantageous for their higher proliferation rate and because they are easy to obtain without ethical concerns. Although MenSCs have exhibited therapeutic efficacy in some diseases, their effects on AD remain elusive. In the present study, we showed that intracerebral transplantation of MenSCs dramatically improved the spatial learning and memory of APP/PS1 mice. In addition, MenSCs significantly ameliorated amyloid plaques and reduced tau hyperphosphorylation in APP/PS1 mice. Remarkably, we also found that intracerebral transplantation of MenSCs markedly increased several Aβ degrading enzymes and modulated a panel of proinflammatory cytokines associated with an altered microglial phenotype, suggesting an Aβ degrading and anti-inflammatory impact of MenSCs in the brains of APP/PS1 mice. In conclusion, these findings suggest that MenSCs are a promising therapeutic candidate for AD.

YKL-40 as a Potential Biomarker and a Possible Target in Therapeutic Strategies of Alzheimer's Disease

Background:

Growing body of evidence suggests that the pathogenesis of Alzheimer’s disease (AD), a progressing neurodegenerative condition, is not limited to the neuronal compartment, but also involves various immunological mechanisms. Insoluble Aβ aggregates in the brain can induce the activation of microglia, resulting in the synthesis of proinflammatory mediators, which further can stimulate astrocytic expression of YKL-40. Therefore, the aim of the current review is to present up-to-date data about the role of YKL-40 as a biomarker of AD as well as the possibility of therapeutic strategies targeting neuroinflammation.

Objective/Methods:

We searched PubMed articles for the terms “YKL-40”, “neurodegeneration”, “neuroinflammation” and “Alzheimer’s disease”, and included papers focusing on this review’s scope.

Results:

Recent studies indicate that CSF concentrations of YKL-40 were significantly higher in AD patients than in cognitively normal individuals and correlated with dementia biomarkers, such as tau proteins and amyloid beta. Determination of YKL-40 CSF concentration may be also helpful in differentiation between types of dementia and in the distinction of patients in the stable phase of MCI from those who progressed to dementia. Moreover, significantly increased levels of YKL-40 mRNA were found in AD brains in comparison with non-demented controls. Additionally, it was suggested that anti-inflammatory treatment might relief the symptoms of AD and slow its progression.

Conclusion:

Based on the recent knowledge, YKL-40 might be useful as a possible biomarker in the diagnosis and prognosis of AD. Modulation of risk factors and targeting of immune mechanisms, including systemic inflammation could lead to future preventive or therapeutic strategies for AD.

The Relationship between Markers of Inflammation and Degeneration in the Central Nervous System and the Blood-Brain Barrier Impairment in Alzheimer's Disease

BACKGROUND

It is known that YKL-40- a marker of glial inflammation, and VILIP-1- a marker of neuronal injury, reflect functional and structural changes in AD brains, although there is limited data concerning their potential influence on blood-brain barrier (BBB) homeostasis.

OBJECTIVE

Therefore, the aim of our study was to investigate the relationship between markers of inflammation and degeneration in the central nervous system (CNS) of patients with AD and mild cognitive impairment (MCI) as well as immunological response in CNS and BBB function.

METHODS

Cerebrospinal fluid (CSF) concentrations of proteins tested were determined in 45 AD patients, 18 MCI subjects, and 23 non-demented controls using ELISA method.

RESULTS

CSF concentrations of YKL-40 were significantly higher in MCI and AD patients, whereas CSF levels of VILIP-1 were statistically higher in the AD group as compared to the subjects without cognitive deficits. Elevated concentrations of YKL-40 correlated significantly with increased albumin quotient and decreased Aβ42/40 ratio in AD patients and with IgG quotient in the total study group. We did not find a relationship between VILIP-1 and immunological parameters reflecting BBB dysfunction and humoral immune response.

CONCLUSION

Our findings indicate that YKL-40 may contribute to decreased stability and increased permeability of BBB in AD patients. It is assumed that YKL-40 is implicated in the development of brain barriers, although its precise mechanism of action in the BBB disruption remains unrevealed. Further studies on larger groups of patients are required to confirm our hypothesis.

Mechanisms of Risk Reduction in the Clinical Practice of Alzheimer's Disease Prevention

Alzheimer’s disease (AD) is a neurodegenerative dementia that affects nearly 50 million people worldwide and is a major source of morbidity, mortality, and healthcare expenditure. While there have been many attempts to develop disease-modifying therapies for late-onset AD, none have so far shown efficacy in humans. However, the long latency between the initial neuronal changes and onset of symptoms, the ability to identify patients at risk based on family history and genetic markers, and the emergence of AD biomarkers for preclinical disease suggests that early risk-reducing interventions may be able to decrease the incidence of, delay or prevent AD. In this review, we discuss six mechanisms—dysregulation of glucose metabolism, inflammation, oxidative stress, trophic factor release, amyloid burden, and calcium toxicity—involved in AD pathogenesis that offer promising targets for risk-reducing interventions. In addition, we offer a blueprint for a multi-modality AD risk reduction program that can be clinically implemented with the current state of knowledge. Focused risk reduction aimed at particular pathological factors may transform AD to a preventable disorder in select cases.

Lipidomic Profiles in Diabetes and Dementia

Lipids are a diverse class of hydrophobic and amphiphilic molecules which make up the bulk of most biological systems and are essential for human life. The role of lipids in health and disease has been recognized for many decades, as evidenced by the early identification of cholesterol as an important risk factor of heart disease and the development and introduction of statins as a one of the most successful therapeutic interventions to date. While several studies have demonstrated an increased risk of dementia, including Alzheimer's disease (AD), in those with diabetes mellitus, the nature of this risk is not well understood. Recent developments in the field of lipidomics, driven primarily by technological advances in high pressure liquid chromatography and particularly mass spectrometry, have enabled the detailed characterization of the many hundreds of individual lipid species in mammalian systems and their association with disease states. Diabetes mellitus and AD have received particular attention due to their prominence in Western societies as a result of the ongoing obesity epidemic and the aging populations. In this review, we examine how these lipidomic studies are informing on the relationship between lipid metabolism with diabetes and AD and how this may inform on the common pathological pathways that link diabetes risk with dementia.

Neuroprotective effects of salidroside administration in a mouse model of Alzheimer's disease

Salidroside administration improves memory in different models of learning. However, its influence on models of Alzheimer's disease (AD) has not been widely studied. In the present study, the therapeutic effect of salidroside was investigated in an animal model of AD. APPswe/PS1ΔE9 mouse (n=20) were randomly divided into either the AD model group or the salidroside + AD model group (n=10 in each group), and C57BL/6J mouse (n=20) of identical age and genetic background were randomly divided into either the normal control (NC) group or the salidroside + NC group (n=10 in each group). The Morris water maze behavioral test was applied to all mice in order to investigate the effects of salidroside administration on learning and memory functions. The concentrations of malondialdehyde (MDA), glutathione (GSH) and nitrate in the hippocampus of the mice were determined, and hippocampal superoxide dismutase (SOD) activity was also determined. In addition, terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling was used to investigate the rate of neuronal apoptosis in the hippocampus. Furthermore, the concentrations of interleukin‑6 (IL‑6) and tumor necrosis factor‑α (TNF‑α) were tested for in the brain tissues of AD mice. Learning and memory functions in AD mice were revealed to improve following administration of salidroside. Furthermore, salidroside administration was revealed to decrease the concentrations of MDA and nitrate in the hippocampus, decrease the apoptotic rate of hippocampal neurons, and increase the activity of SOD and the concentration of GSH in hippocampal tissue. In addition, it was demonstrated that salidroside administration suppressed the expression levels of IL‑6 and TNF‑α. In conclusion, this study revealed that the administration of salidroside could attenuate the effects of AD‑associated memory and learning impairment in mice. Furthermore, it was demonstrated that the effects of salidroside administration on AD mice were, at least partially, via inhibition of brain oxidative/nitrosative damage, suppression of both IL‑6 and TNF‑α expression levels, and suppression of the hippocampal neuronal apoptotic rate.

A novel silanization agent based single used biosensing system: Detection of C-reactive protein as a potential Alzheimer's disease blood biomarker

This paper illustrates a new and sensitive electrochemical immunosensor for the analysis of C-reactive protein. Indium Tin Oxide (ITO) disposable sheets were modified by using 3-cyanopropyltrimethoxysilane (CPTMS) self-assembled monolayers (SAMs) for the first time for immobilizing the anti-CRP antibody via covalent interactions without the need for any cross-linking agent. Cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), as well as square wave voltammetry (SWV) methods were applied to characterize immobilization steps of anti-CRP and to determine the CRP concentration. The optimization of the fabricated parameters and the analytical performance of the biosensor were widely evaluated. Charge transfer resistance changes were highly linear and sensitive with CRP concentration of 3.25-208 fg mL^-1 range and associated with a limit of detection of 0.455 fg mL^-1. This impedimetric biosensing system have excellent repeatability, reproducibility and reusability. Moreover, the binding characterization of CRP to anti-CRP was monitored by a single frequency impedance technique. The amount of CRP in human serum samples were analyzed by fabricated biosensor to determine the feasibility of the biosensing system in medical purposes. We suggest that CPTMS, a new silanization agent, is ideal in biosensor applications.

S-glutathionylation exerts opposing roles in the regulation of STAT1 and STAT3 signaling in reactive microglia

STAT1 and STAT3 are two transcription factors involved in a lot of cellular functions such as immune response, proliferation, apoptosis, and cell survival. A number of literature evidences described a yin-yang relationship between activation of STAT1 and STAT3 in neurodegenerative disorders where STAT1 exerts a pro-apoptotic effect whereas STAT3 shows neuroprotective properties through the inhibition of apoptosis. Although the role of oxidative-stress in the pathogenesis of neurodegeneration is clearly described, its influence in the regulation of these pathways is poorly understood. Herein, we demonstrate that H₂O₂ rapidly induces phosphorylation of STAT1 whereas it is not able to influence phosphorylation of STAT3 in mouse microglia BV2 cells. The analysis of the molecular mechanism of STATs signaling reveals that H₂O₂ induces S-glutathionylation of both STAT1 and STAT3. The same post-translational event exerts an opposing role in the regulation of STAT1 and STAT3 signaling. These data not only confirm redox sensibility of STAT3 signaling but also reveal for the first time that STAT1 is susceptible to redox regulation. A deep study of the molecular mechanism of STAT1 redox regulation, identifies Cys324 and Cys492 as the main targets of S-glutathionylation and confirms that S-glutathionylation does not impair JAK2 mediated STAT1 tyrosine phosphorylation. These results demonstrate that both phosphorylation and glutathionylation contribute to activation of STAT1 during oxidative stress and underline that the same post-translation event exerts an opposing role in the regulation of STAT1 and STAT3 signaling in microglia cells.

Inhibition of cyclin-dependent kinase 5 affects early neuroinflammatory signalling in murine model of amyloid beta toxicity

BACKGROUND

Cyclin-dependent kinase 5 (Cdk5) belongs to the family of proline-directed serine/threonine kinases and plays a critical role in neuronal differentiation, migration, synaptogenesis, plasticity, neurotransmission and apoptosis. The deregulation of Cdk5 activity was observed in post mortem analysis of brain tissue of Alzheimer's disease (AD) patients, suggesting the involvement of Cdk5 in the pathomechanism of this neurodegenerative disease. However, our recent study demonstrated the important function of Cdk5 in regulating inflammatory reaction.

METHODS

Since the role of Cdk5 in regulation of inflammatory signalling in AD is unknown, we investigated the involvement of Cdk5 in neuroinflammation induced by single intracerebroventricular (icv) injection of amyloid beta protein (Aβ) oligomers in mouse. The brain tissue was analysed up to 35 days post injection. Roscovitine (intraperitoneal administration) was used as a potent Cdk5 inhibitor. The experiments were also performed on human neuroblastoma SH-SY5Y as well as mouse BV2 cell lines treated with exogenous oligomeric Aβ.

RESULTS

Our results demonstrated that single injection of Aβ oligomers induces long-lasting activation of microglia and astrocytes in the hippocampus. We observed also profound, early inflammatory response in the mice hippocampus, leading to the significant elevation of pro-inflammatory cytokines expression (e.g. TNF-α, IL-1β, IL-6). Moreover, Aβ oligomers elevated the formation of truncated protein p25 in mouse hippocampus and induced overactivation of Cdk5 in neuronal cells. Importantly, administration of roscovitine reduced the inflammatory processes evoked by Aβ in the hippocampus, leading to the significant decrease of cytokines level.

CONCLUSIONS

These studies clearly show the involvement of Cdk5 in modulation of brain inflammatory response induced by Aβ and may indicate this kinase as a novel target for pharmacological intervention in AD.

Ameliorative effects and possible molecular mechanisms of action of fibrauretine from Fibraurea recisa Pierre on d-galactose/AlCl3-mediated Alzheimer's disease

Fibrauretine is one of the main active ingredients from the rattan stems of Fibraurea recisa Pierre It exhibits a series of significant pharmacological effects. The present study aimed to evaluate the potential anti Alzheimer's disease (AD) effects of fibrauretine on a d-galactose/AlCl₃-induced mouse model, and the underlying mechanisms of action were further investigated for the first time. Our results showed that pretreatment with fibrauretine significantly improved the ability of spatial short-term working memory in the model mice during the Y-maze test, as well as the abilities of spatial learning and memory during the Morris water maze. The levels of brain tissue amyloid (Aβ), P-Tau, Tau and acetylcholinesterase (AchE) were evidently increased in d-galactose/AlCl₃-intoxicated mice, and these effects were reversed by fibrauretine. In contrast, a significant increase in the levels of the neurotransmitter acetylcholine (Ach) and choline acetyl transferase (ChAT) was observed in the fibrauretine-treated groups compared with the model group. Neuronal oxidative stress, evidenced by increased malondialdehyde (MDA) and nitric oxide (NO) levels and a decline in glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) activity, was significantly alleviated by fibrauretine pretreatment. The suppression of the neuroinflammatory response by fibrauretine was realized not only by the decrease in the levels of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the brain tissues and by the enzyme-linked immunosorbent assay (ELISA) but also by the protein expression levels of nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS), which were measured by immunohistochemistry and western blotting. In addition, the protein expression levels of inflammatory factors interleukin-33 (IL-33) and ST2 in the brain tissues were detected by immunohistochemistry. Furthermore, the effects of western blotting demonstrated that the administration of fibrauretine significantly suppressed the protein expression levels of caspase-3, cleaved caspase-3, and Bax and increased the protein expression levels of Bcl-2, and the results of the H&E and TUNEL assay all suggested the inhibition of apoptosis in the neurons. The results clearly suggest that the underlying molecular mechanisms of action of the fibrauretine-mediated alleviation of d-galactose/AlCl₃-induced Alzheimer's disease may involve antioxidant, anti-inflammatory, and anti-apoptotic effects.

Fibrauretine from Fibraurea recisa Pierre exhibits ameliorative effects on d-galactose/AlCl₃-induced Alzheimer's disease. Its mechanism may involve its antioxidant, anti-inflammatory and anti-apoptotic effects.

Leptin and ghrelin: Sewing metabolism onto neurodegeneration

Life expectancy has considerably increased over the last decades. The negative consequence of this augmented longevity has been a dramatic increase of age-related chronic neurodegenerative diseases, such as Alzheimer's, Parkinson's and multiple sclerosis. Epidemiology is telling us there exists a strong correlation between the neuronal loss characterizing these disorders and metabolic dysfunction. This review aims at presenting the evidence supporting the existence of a molecular system linking metabolism with neurodegeneration, with a specific focus on the role of two hormones with a key role in the regulatory cross talk between metabolic imbalance and the damage of nervous system: leptin and ghrelin. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'