Inflammation and Alzheimer's disease: relationships between pathogenic mechanisms and clinical expression

Alzheimer’s disease – the journey of a healthy brain into organ failure

As the most common dementia, Alzheimer’s disease (AD) exacts an immense personal, societal, and economic toll. AD was first described at the neuropathological level in the early 1900s. Today, we have mechanistic insight into select aspects of AD pathogenesis and have the ability to clinically detect and diagnose AD and underlying AD pathologies in living patients. These insights demonstrate that AD is a complex, insidious, degenerative proteinopathy triggered by Aβ aggregate formation. Over time Aβ pathology drives neurofibrillary tangle (NFT) pathology, dysfunction of virtually all cell types in the brain, and ultimately, overt neurodegeneration. Yet, large gaps in our knowledge of AD pathophysiology and huge unmet medical need remain. Though we largely conceptualize AD as a disease of aging, heritable and non-heritable factors impact brain physiology, either continuously or at specific time points during the lifespan, and thereby alter risk for devolvement of AD. Herein, I describe the lifelong journey of a healthy brain from birth to death with AD, while acknowledging the many knowledge gaps that remain regarding our understanding of AD pathogenesis. To ensure the current lexicon surrounding AD changes from inevitable, incurable, and poorly manageable to a lexicon of preventable, curable, and manageable we must address these knowledge gaps, develop therapies that have a bigger impact on clinical symptoms or progression of disease and use these interventions at the appropriate stage of disease.

Microglia in Alzheimer's Disease: a Key Player in the Transition Between Homeostasis and Pathogenesis

Immune activation accompanies the development of proteinopathy in the brains of Alzheimer's dementia patients. Evolving from the long-held viewpoint that immune activation triggers the pathological trajectory in Alzheimer's disease, there is accumulating evidence now that microglial activation is neither pro-amyloidogenic nor just a simple reactive process to the proteinopathy. Preclinical studies highlight an interesting aspect of immunity, i.e., spurring immune system activity may be beneficial under certain circumstances. Indeed, a dynamic evolving relationship between different activation states of the immune system and its neuronal neighbors is thought to regulate overall brain organ health in both healthy aging and progression of Alzheimer's dementia. A new premise evolving from genome, transcriptome, and proteome data is that there might be at least two major phases of immune activation that accompany the pathological trajectory in Alzheimer's disease. Though activation on a chronic scale will certainly lead to neurodegeneration, this emerging knowledge of a potential beneficial aspect of immune activation allows us to form holistic insights into when, where, and how much immune system activity would need to be tuned to impact the Alzheimer's neurodegenerative cascade. Even with the trove of recently emerging -omics data from patients and preclinical models, how microglial phenotypes are functionally related to the transition of a healthy aging brain towards progressive degenerative state remains unknown. A deeper understanding of the synergism between microglial functional states and brain organ health could help us discover newer interventions and therapies that enable us to address the current paucity of disease-modifying therapies in Alzheimer's disease.

Anti-Inflammatory Agents: An Approach to Prevent Cognitive Decline in Alzheimer's Disease

Systemic inflammation is an organism's response to an assault by the non-self. However, that inflammation may predispose humans to illnesses targeted to organs, including Alzheimer's disease (AD). Lesions in AD have pro-inflammatory cytokines and activated microglial/monocyte/macrophage cells. Up to this point, clinical trials using anti-amyloid monoclonal antibodies have not shown success. Maybe it is time to look elsewhere by combating inflammation. Neuroinflammation with CNS cellular activation and excessive expression of immune cytokines is suspected as the "principal culprit" in the higher risk for sporadic AD. Microglia, the resident immune cell of the CNS, perivascular myeloid cells, and activated macrophages produce IL-1, IL-6 at higher levels in patients with AD. Anti-inflammatory measures that target cellular/cytokine-mediated damage provide a rational therapeutic strategy. We propose a clinical trial using oral type 1 IFNs to act as such an agent; one that decreases IL-1 and IL-6 secretion by activating lamina propria lymphocytes in the gut associated lymphoid tissue with subsequent migration to the brain undergoing inflammatory responses. A clinical trial would be double-blind, parallel 1-year clinical trial randomized 1 : 1 oral active type 1 IFN versus best medical therapy to determine whether ingested type I IFN would decrease the rate of cognitive decline in mild cognitive impairment or mild AD. Using cognitive psychometrics, imaging, and fluid biomarkers (MxA for effective type I IFN activity beyond the gut), we can determine if oral type I IFN can prevent cognitive decline in AD.

Identification and Preliminary Validation of a Plasma Profile Associated with Cognitive Decline in Dementia and At-Risk Individuals: A Retrospective Cohort Analysis

Biomarker discovery is a major need for earlier dementia diagnosis. We evaluated a plasma signature of amyloid, metallo-proteinases (MMPs), and inflammatory markers in a cohort of at-risk individuals and individuals clinically diagnosed with probable Alzheimer's disease (pAD). Using multiplex arrays, we measured Aβ40, Aβ42, MMP-1, MMP-3, MMP-9, IFN-γ, TNF-α, IL-6, IL-8, and IL-10 in plasma from 107 individuals followed every 6 months for 3 years. Final diagnoses included: pAD (n = 28), mild cognitive impairment (MCI, n = 30), subjective memory impairment (SMI, n = 30), and asymptomatic (NCI, n = 19). Blood was drawn at final follow-up. We used linear and logistic regressions to examine biomarker associations with prior known decline on the Montreal Cognitive Assessment (MoCA) and the Cambridge Cognitive Examination (CAMCOG); as well disease progression by the time of blood-draw. We derived a biomarker composite from the individual markers, and tested its association with a clinical diagnosis of pAD. Lower Aβ40 and Aβ42 and higher IL-8, IL-10, and TNF-α were associated with greater cognitive decline per the MoCA and CAMCOG. MMP-3 was higher in SMI, MCI, and pAD than NCI. Whereas the other investigative molecules did not differ between groups, composite scores-created using MoCA/CAMCOG-based trends in Aβ40, Aβ42, MMP-1, MMP-3, IL-8, IL-10, and TNF-α- were associated with a final diagnosis of pAD (c-statistic 0.732 versus 0.602 for age-sex alone). Thus, plasma amyloid, MMP, and inflammatory biomarkers demonstrated differences in individuals with cognitive deterioration and/or progression to MCI/pAD. Our findings support studying these markers earlier in the continuum of probable AD as well as in specific dementias.

Harnessing Immunoproteostasis to Treat Neurodegenerative Disorders

Immunoproteostasis is a term used to reflect interactions between the immune system and the proteinopathies that are presumptive "triggers" of many neurodegenerative disorders. The study of immunoproteostasis is bolstered by several observations. Mutations or rare variants in genes expressed in microglial cells, known to regulate immune functions, or both can cause, or alter risk for, various neurodegenerative disorders. Additionally, genetic association studies identify numerous loci harboring genes that encode proteins of known immune function that alter risk of developing Alzheimer's disease (AD) and other neurodegenerative proteinopathies. Further, preclinical studies reveal beneficial effects and liabilities of manipulating immune pathways in various neurodegenerative disease models. Although there are concerns that manipulation of the immune system may cause more harm than good, there is considerable interest in developing immune modulatory therapies for neurodegenerative disorders. Herein, I highlight the promise and challenges of harnessing immunoproteostasis to treat neurodegenerative proteinopathies.

Differential deregulation of NGF and BDNF neurotrophins in a transgenic rat model of Alzheimer's disease

Evidence from human neuropathological studies indicates that the levels of the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are compromised in Alzheimer's disease. However, the causes and temporal (pathology-dependent) evolution of these alterations are not completely understood. To elucidate these issues, we investigated the McGill-R-Thy1-APP transgenic rat, which exhibits progressive intracellular and extracellular amyloid-beta (Aβ) pathology and ensuing cognitive deficits. Neurochemical analyses revealed a differential dysregulation of NGF and BDNF transcripts and protein expression. While BDNF mRNA levels were significantly reduced at very early stages of amyloid pathology, before plaques appeared, there were no changes in NGF mRNA expression even at advanced stages. Paradoxically, the protein levels of the NGF precursor were increased. These changes in neurotrophin expression are identical to those seen during the progression of Alzheimer's disease. At advanced pathological stages, deficits in the protease cascade controlling the maturation and degradation of NGF were evident in McGill transgenic rats, in line with the paradoxical upregulation of proNGF, as seen in Alzheimer's disease, in the absence of changes in NGF mRNA. The compromise in NGF metabolism and BDNF levels was accompanied by downregulation of cortical cholinergic synapses; strengthening the evidence that neurotrophin dysregulation affects cholinergic synapses and synaptic plasticity. Our findings suggest a differential temporal deregulation of NGF and BDNF neurotrophins, whereby deficits in BDNF mRNA appear at early stages of intraneuronal Aβ pathology, before alterations in NGF metabolism and cholinergic synapse loss manifest.

An inflammatory and trophic disconnect biomarker profile revealed in Down syndrome plasma: Relation to cognitive decline and longitudinal evaluation

INTRODUCTION

Given that Alzheimer's pathology develops silently over decades in Down syndrome (DS), prognostic biomarkers of dementia are a major need.

METHODS

We investigated the plasma levels of Aβ, proNGF, tPA, neuroserpin, metallo-proteases and inflammatory molecules in 31 individuals with DS (with and without dementia) and in 31 healthy controls. We examined associations between biomarkers and cognitive decline.

RESULTS

Aβ40 and Aβ42 were elevated in DS plasma compared to controls, even in DS individuals without dementia. Plasma Aβ correlated with the rate of cognitive decline across 2 years. ProNGF, MMP-1, MMP-3, MMP-9 activity, TNF-α, IL-6, and IL-10 were higher in DS plasma, even at AD-asymptomatic stages. Declining plasma Aβ42 and increasing proNGF levels correlated with cognitive decline. A combined measure of Aβ and inflammatory molecules was a strong predictor of prospective cognitive deterioration.

CONCLUSIONS

Our findings support the combination of plasma and cognitive assessments for the identification of DS individuals at risk of dementia.

Does aspirin-induced oxidative stress cause asthma exacerbation?

Aspirin-induced asthma (AIA) is a distinct clinical syndrome characterized by severe asthma exacerbations after ingestion of aspirin or other non-steroidal anti-inflammatory drugs. The exact pathomechanism of AIA remains unknown, though ongoing research has shed some light. Recently, more and more attention has been focused on the role of aspirin in the induction of oxidative stress, especially in cancer cell systems. However, it has not excluded the similar action of aspirin in other inflammatory disorders such as asthma. Moreover, increased levels of 8-isoprostanes, reliable biomarkers of oxidative stress in expired breath condensate in steroid-naïve patients with AIA compared to AIA patients treated with steroids and healthy volunteers, has been observed. This review is an attempt to cover aspirin-induced oxidative stress action in AIA and to suggest a possible related pathomechanism.

C-reactive protein plays a marginal role in cognitive decline: a systematic review and meta-analysis

OBJECTIVE

The objective of the study was to investigate the association between peripheral levels of C-reactive protein (CRP) and cognitive decline that is defined by 2-5 years of cognitive change in general cognitive function or specific cognitive domain.

METHODS

We searched PubMed and Google for prospective/longitudinal studies that report the association between peripheral levels of CRP and risk of cognitive decline in the nondementia population.

RESULTS

Out of 479 related articles from PubMed and Google, four studies with a total of 5255 non-demented subjects that report odds ratio (OR)/relative risk/hazard ratio of CRP levels and decline in general cognition met our criteria for meta-analysis. The association between higher levels of CRP and risk of global cognitive decline was weak but significant (OR, 1.27 [95% CI, 1.02 to 1.58]). However, the systematic review from six other articles that were not suitable for meta-analysis revealed a marginal association between CRP and cognitive decline in certain domains.

CONCLUSION

Our analysis demonstrated a weak association between peripheral CRP level and global cognitive decline. Because of the small number of included studies and varied methodologies that they applied, caution should be taken when generalizing our finding to the full range of cognitive changes in different cognitive domains observed in non-demented people.

Prominence of central sphingosine-1-phosphate receptor-1 in attenuating aβ-induced injury by fingolimod

FTY720 (fingolimod), the sphingosine-1-phosphate (S1P) analogue, has been experimentally indicated to exert substantial ameliorating effects in animal models of Alzheimer's disease (AD). The present work aims to answer whether central S1P receptor 1 (S1P1) plays significant role in the impact of fingolimod in AD. To verify the prominence of central FTY720 phosphorylation, DMS (sphingosine kinase inhibitor) was infused intracerebrally in parallel with systemic FTY720 administration to prevent central formation of FTY720-P as the recognized active ligand for S1PRs. The corresponding S1P1 modulation was also investigated using the pharmacological blockage of central S1P1 by W123. Both DMS and W123 were efficiently capable of suppressing FTY720-ameliorating effects in AD animals, either on memory deficit or on COX-II and TNF-α expression. Our data conclude that experimental benefits of FTY720 in the context of AD depend on central S1P1 modulation, as well as on S1P kinase activity in the brain.

Nerve growth factor metabolic dysfunction in Alzheimer's disease and Down syndrome

Alzheimer's disease (AD) is a devastating neurodegenerative condition and the most common type of amnestic dementia in the elderly. Individuals with Down syndrome (DS) are at increased risk of developing AD in adulthood as a result of chromosome 21 trisomy and triplication of the amyloid precursor protein (APP) gene. In both conditions, the central nervous system (CNS) basal forebrain cholinergic system progressively degenerates, and such changes contribute to the manifestation of cognitive decline and dementia. Given the strong dependency of these neurons on nerve growth factor (NGF), it was hypothesized that their atrophy was caused by NGF deficits. However, in AD, the synthesis of NGF is not affected at the transcript level and there is a marked increase in its precursor, proNGF. This apparent paradox remained elusive for many years. In this review, we discuss the recent evidence supporting a CNS deficit in the extracellular metabolism of NGF, both in AD and in DS brains. We describe the nature of this trophic disconnection and its implication for the atrophy of basal forebrain cholinergic neurons. We further discuss the potential of NGF pathway markers as diagnostic indicators of a CNS trophic disconnection.

Inflammation and clinical presentation in neurodegenerative disease: a volatile relationship

A proposed immune mechanism that potentially modifies or exacerbates neurodegenerative disease presentation in older adults has received considerable attention in the past decade, with recent studies demonstrating a strong link between pro-inflammatory markers and neurodegeneration. The overarching aim of the following review is to synthesize recent research that supports a possible relationship between inflammation and clinical features of neurodegenerative diseases, including risk of development, cognitive and clinical correlates, and progression of the specified diseases. Specific emphasis is placed on providing a temporal context for the association between inflammation and neurodegeneration.

A review of experimental evidence linking neurotoxic organophosphorus compounds and inflammation

Organophosphorus (OP) nerve agents and pesticides inhibit acetylcholinesterase (AChE), and this is thought to be a primary mechanism mediating the neurotoxicity of these compounds. However, a number of observations suggest that mechanisms other than or in addition to AChE inhibition contribute to OP neurotoxicity. There is significant experimental evidence that acute OP intoxication elicits a robust inflammatory response, and emerging evidence suggests that chronic repeated low-level OP exposure also upregulates inflammatory mediators. A critical question that is just beginning to be addressed experimentally is the pathophysiologic relevance of inflammation in either acute or chronic OP intoxication. The goal of this article is to provide a brief review of the current status of our knowledge linking inflammation to OP intoxication, and to discuss the implications of these findings in the context of therapeutic and diagnostic approaches to OP neurotoxicity.

Proteinopathy-induced neuronal senescence: a hypothesis for brain failure in Alzheimer's and other neurodegenerative diseases

Background

Alzheimer's disease (AD) and a host of other neurodegenerative central nervous system (CNS) proteinopathies are characterized by the accumulation of misfolded protein aggregates. Simplistically, these aggregates can be divided into smaller, soluble, oligomeric and larger, less-soluble or insoluble, fibrillar forms. Perhaps the major ongoing debate in the neurodegenerative disease field is whether the smaller oligomeric or larger fibrillar aggregates are the primary neurotoxin. Herein, we propose an integrative hypothesis that provides new insights into how a variety of misfolded protein aggregates can result in neurodegeneration.

Results

We introduce the concept that a wide range of highly stable misfolded protein aggregates in AD and other neurodegenerative proteinopathies are recognized as non-self and chronically activate the innate immune system. This pro-inflammatory state leads to physiological senescence of CNS cells. Once CNS cells undergo physiological senescence, they secrete a variety of pro-inflammatory molecules. Thus, the senescence of cells, which was initially triggered by inflammatory stimuli, becomes a self-reinforcing stimulus for further inflammation and senescence. Ultimately, senescent CNS cells become functionally impaired and eventually die, and this neurodegeneration leads to brain organ failure.

Conclusion

This integrative hypothesis, which we will refer to as the proteinopathy-induced senescent cell hypothesis of AD and other neurodegenerative diseases, links CNS proteinopathies to inflammation, physiological senescence, cellular dysfunction, and ultimately neurodegeneration. Future studies characterizing the senescent phenotype of CNS cells in AD and other neurodegenerative diseases will test the validity of this hypothesis. The implications of CNS senescence as a contributing factor to the neurodegenerative cascade and its implications for therapy are discussed.

Impairment of long-term depression induced by chronic brain inflammation in rats

Although deficits in synaptic plasticity have been identified in aged or neuroinflamed animals with memory impairments, few studies have examined the cellular basis of plasticity in such animals. Here, we examined whether chronic neuroinflammation altered long-term depression (LTD) and studied the underlying mechanism of LTD impairment by neuroinflammation. Chronic neuroinflammation was induced by administration of lipopolysaccharide (LPS) to the fourth ventricle. Excitatory postsynaptic potentials were recorded extracellularly in the rat hippocampal CA1 area to examine alterations in synaptic plasticity. Chronic administration of LPS induced remarkable memory impairment in the Morris water maze test. N-methyl-d-aspartate receptor (NMDAR)-dependent LTD was almost absent in LPS-infused animals. The AMPA receptor (AMPAR)-mediated synaptic response was reduced in the LPS-infused group. These results suggest that reduction in NMDAR-dependent LTD might arise because of alterations in postsynaptic AMPARs as well as NMDARs and that such changes may be present in mild and early forms of Alzheimer-type dementia.

Chronic brain inflammation impairs two forms of long-term potentiation in the rat hippocampal CA1 area

Neuroinflammation plays an important role in the progression of Alzheimer's disease (AD) and is characterized by the presence of activated microglia. We investigated whether chronic neuroinflammation affects the induction of N-methyl-d-aspartate receptor (NMDAR)-dependent long-term potentiation (LTP) and NMDAR-independent LTP which is expressed by voltage-dependent calcium channel (VDCC). Chronic neuroinflammation was induced by administration of lipopolysaccharide (LPS) (28 days, 0.35 microg/h) to the fourth ventricle. The Morris water maze test was conducted to measure the memory impairment and then excitatory postsynaptic potentials were recorded extracelluarly from stratum radiatum in the rat hippocampal CA1 area to examine the changes in synaptic plasticity induced by LPS infusion. Chronic administration of LPS induced remarkable memory impairment. The field recording experiments revealed that the induction of both NMDAR-dependent LTP and NMDAR-independent LTP were impaired in the hippocampal Schaffer collateral-CA1 synapse in animals chronically infused with LPS. The present results show that chronic neuroinflammation can lead to the impaired spatial memory and attenuation of VDCC-dependent LTP as well as NMDAR-dependent LTP. The attenuation of synaptic plasticity may be caused by the impairment of both NMDAR and L-type Ca2+ via elevated levels of inflammatory proteins, which may underlie aspects of dementia.

The effects of NOS2 gene deletion on mice expressing mutated human AbetaPP

Nitric oxide synthase 2 (NOS2) and its gene product, inducible NOS (iNOS) play an important role in neuroinflammation by generating nitric oxide (NO), a critical signaling and redox factor in the brain. Although NO is associated with tissue damage, it can also promote cell survival. We hypothesize that during long-term exposure to amyloid-beta (Abeta) in Alzheimer's disease (AD), NO levels fall in the brain to a threshold at which the protective effects of NO cannot be sustained, promoting Abeta mediated damage. Two new mouse models of AD have been developed that utilize this concept of NO's action. These mice express human amyloid-beta protein precursor (AbetaPP) mutations that generate Abeta peptides on a mouse NOS2 knockout background. The APP/NOS2(-/-) bigenic mice progress from Abeta production and amyloid deposition to hyperphosphorylated normal mouse tau at AD-associated epitopes, aggregation and redistribution of tau to somatodendritic regions of neurons and significant neuronal loss including loss of interneurons. This AD-like pathology is accompanied by robust behavioral changes. As APP/NOS2(-/-) bigenic mice more fully model the human AD disease pathology, they may serve as a tool to better understand disease progression in AD and the role of NO in altering chronic neurological disease processes.

The APOE4 genotype alters the response of microglia and macrophages to 17beta-estradiol

The apolipoprotein E4 (APOE4) gene is a well-known risk factor for Alzheimer's disease (AD) and other neurological disorders. Post-menopausal women with AD who express at least one APOE4 gene have more severe neuropathology and worsened cognitive scores than their non-expressing counterparts. Since 17beta-estradiol down-regulates inflammation as part of its neuroprotective role, we examined the effect of 17beta-estradiol on the response of microglia to immune activation as a function of APOE genotype. Our data show that the anti-inflammatory activity of 17beta-estradiol is significantly reduced in APOE4 targeted replacement mice compared to APOE3 mice. A significant interaction between APOE genotype and the response to 17beta-estradiol was observed for NO and cytokine production by immune activated microglia. The genotype specific effect was not restricted to brain macrophages since peritoneal macrophages from APOE4 ovariectomized mice also demonstrated a significant difference in 17beta-estradiol responsiveness. ERbeta protein levels in APOE4 microglia were higher than APOE3 microglia, suggesting a difference in post-translational protein regulation in the presence of the APOE4 gene. Overall, our data indicate that the APOE genotype may be a critical component in assessing the effectiveness of 17beta-estradiol's action and may impact the neuroprotective role of 17beta-estradiol and of hormone replacement therapy on brain function when the APOE4 gene is expressed.

Role of the toll-like receptor 4 in neuroinflammation in Alzheimer's disease

Microglial activation is a key feature in Alzheimer's disease and is considered to contribute to progressive neuronal injury by release of neurotoxic products. The innate immune receptor Toll-like-receptor 4 (TLR4), localized on the surface of microglia, is a first-line host defense receptor against invading microorganisms. Here, we show that a spontaneous loss-of-function mutation in the Tlr4 gene strongly inhibits microglial and monocytic activation by aggregated Alzheimer amyloid peptide resulting in a significantly lower release of the inflammatory products IL-6, TNFalpha and nitric oxide. Treatment of primary murine neuronal cells with supernatant of amyloid peptide-stimulated microglia demonstrates that Tlr4 contributes to amyloid peptide-induced microglial neurotoxicity. In addition, stimulation experiments in transfected HEK293 cells allowed to define a tri-molecular receptor complex consisting of TLR4, MD-2 and CD14 necessary for full cellular activation by aggregated amyloid peptide. A clinical relevance of these findings is supported by a marked upregulation of Tlr4 mRNA in APP transgenic mice and by an increased expression of TLR4 in Alzheimer's disease brain tissue associated with amyloid plaque deposition. Together, these observations provide the first evidence for a role of the key innate immune receptor, TLR4, in neuroinflammation in Alzheimer's disease.

Transition from enhanced T cell infiltration to inflammation in the myelin-degenerative central nervous system

Myelin degeneration in the central nervous system (CNS) is often associated with elevated numbers of T cells in brain and spinal cord (SC). In some degenerative diseases, this T cell immigration has no clinical relevance, in others, it may precede severe inflammation and tissue damage. We studied T cells in the myelin-degenerative SC of transgenic (tg) Lewis rats overexpressing the proteolipid protein (PLP). These lymphocytes are T(H)1/T(C)1 cells and represent different T cell clones unique to individual animals. The SC-infiltrating CD8(+) T cell pool is more restricted than its CD4(+) counterpart, possibly due to constrictions in the peripheral CD8(+) T cell repertoire. Some SC-infiltrating T cells are highly motile and cover large distances within their target tissue, others are tethered to MHC class II(+) microglia cells. The activation of the tethered cells may trigger the formation of inflammatory foci and could pave the way for inflammation in degenerative CNS disease.

Cytokines and acute phase response in delirium

OBJECTIVE

This study aimed to examine the expression patterns of pro- and anti-inflammatory cytokines in elderly patients with and without delirium who were acutely admitted to the hospital.

METHODS

All consecutive patients aged 65 years and older, who were acutely admitted to the Department of Internal Medicine of the Academic Medical Center, Amsterdam, a tertiary university teaching hospital, were invited. Members of the geriatric consultation team completed a multidisciplinary evaluation for all study participants within 48 h after admission, including cognitive and functional examination by validated measures of delirium, memory, and executive function. C-reactive protein and cytokines (IL-1beta, IL-6, TNF-alpha, IL-8, and IL-10) were determined within 3 days after admission.

RESULTS

In total, 185 patients were included; mean age was 79 years; 42% were male; and 34.6% developed delirium within 48 h after admission. Compared to patients without delirium, patients with delirium were older and had experienced preexistent cognitive impairment more often. In patients with delirium, significantly more IL-6 levels (53% vs. 31%) and IL-8 levels (45% vs. 22%) were above the detection limit as compared with patients who did not have delirium. After adjusting for infection, age, and cognitive impairment, these differences were still significant.

CONCLUSIONS

Proinflammatory cytokines may contribute to the pathogenesis of delirium in acutely admitted elderly patients.

Induction of the formyl peptide receptor 2 in microglia by IFN-gamma and synergy with CD40 ligand

Human formyl peptide receptor (FPR)-like 1 (FPRL1) and its mouse homologue mFPR2 are functional receptors for a variety of exogenous and host-derived chemotactic peptides, including amyloid beta 1-42 (Abeta(42)), a pathogenic factor in Alzheimer's disease. Because mFPR2 in microglial cells is regulated by proinflammatory stimulants including TLR agonists, in this study we investigated the capacity of IFN-gamma and the CD40 ligand (CD40L) to affect the expression and function of mFPR2. We found that IFN-gamma, when used alone, induced mFPR2 mRNA expression in a mouse microglial cell line and primary microglial cells in association with increased cell migration in response to mFPR2 agonists, including Abeta(42). IFN-gamma also increased the endocytosis of Abeta(42) by microglial cells via mFPR2. The effect of IFN-gamma on mFPR2 expression in microglial cells was dependent on activation of MAPK and IkappaB-alpha. IFN-gamma additionally increased the expression of CD40 by microglial cells and soluble CD40L significantly promoted cell responses to IFN-gamma during a 6-h incubation period by enhancing the activation of MAPK and IkappaB-alpha signaling pathways. We additionally found that the effect of IFN-gamma and its synergy with CD40L on mFPR2 expression in microglia was mediated in part by TNF-alpha. Our results suggest that IFN-gamma and CD40L, two host-derived factors with increased concentrations in inflammatory central nervous system diseases, may profoundly affect microglial cell responses in the pathogenic process in which mFPR2 agonist peptides are elevated.

Potential role of N-methyl-D-aspartate receptors as executors of neurodegeneration resulting from diverse insults: focus on memantine

Glutamatergic neurotransmission is critical to normal learning and memory and when the activity of glutamate neurons becomes excessive, or the normal function of its primary receptors becomes dysfunctional, this may lead to pathological changes associated with age-related neurodegenerative diseases. Anomalous glutamatergic activity associated with Alzheimer's disease may be due to a postsynaptic receptor and downstream defects that produce inappropriately timed or sustained glutamate activation of N-methyl-D-aspartate receptors, leading to neuronal injury and death and cognitive deficits associated with dementia. The mechanisms leading to the condition of chronically depolarized membranes on vulnerable neurons in the Alzheimer's disease brain are likely due to a complex interaction between oxidative stress, mitochondrial failure, chronic brain inflammation and the presence of amyloid-beta and hyperphosphorylated-tau; each of these factors are highly interrelated with each other and are discussed with an emphasis upon potential therapeutic mechanisms underlying the neuroprotective actions of memantine.

Hematologic risk factors of vascular disease and their relation to dementia

Multiple studies have implicated vascular-related conditions as risk factors for dementia. Clarification of these factors in dementia is important because most are modifiable, and may serve as the basis for preventive strategies. Several hematologic factors are associated with vascular diseases, but their relation to dementia is unclear. This review examines biological and epidemiological evidence concerning the role of these hematologic factors in dementia, and dementia subtypes. Reviewed factors include homocysteine, cholesterol, fatty acids, antioxidants, and C-reactive protein. The vast majority of studies reviewed are cross-sectional. Longitudinal studies with serial hematologic measures are needed to clarify the relationship between these factors and dementia over the lifespan. A necessary step is to examine multiple hematologic factors simultaneously, rather than in isolation, to determine how these factors are interrelated.

Expression profiles for macrophage alternative activation genes in AD and in mouse models of AD

Background

Microglia are associated with neuritic plaques in Alzheimer disease (AD) and serve as a primary component of the innate immune response in the brain. Neuritic plaques are fibrous deposits composed of the amyloid beta-peptide fragments (Abeta) of the amyloid precursor protein (APP). Numerous studies have shown that the immune cells in the vicinity of amyloid deposits in AD express mRNA and proteins for pro-inflammatory cytokines, leading to the hypothesis that microglia demonstrate classical (Th-1) immune activation in AD. Nonetheless, the complex role of microglial activation has yet to be fully explored since recent studies show that peripheral macrophages enter an "alternative" activation state.

Methods

To study alternative activation of microglia, we used quantitative RT-PCR to identify genes associated with alternative activation in microglia, including arginase I (AGI), mannose receptor (MRC1), found in inflammatory zone 1 (FIZZ1), and chitinase 3-like 3 (YM1).

Results

Our findings confirmed that treatment of microglia with anti-inflammatory cytokines such as IL-4 and IL-13 induces a gene profile typical of alternative activation similar to that previously observed in peripheral macrophages. We then used this gene expression profile to examine two mouse models of AD, the APPsw (Tg-2576) and Tg-SwDI, models for amyloid deposition and for cerebral amyloid angiopathy (CAA) respectively. AGI, MRC1 and YM1 mRNA levels were significantly increased in the Tg-2576 mouse brains compared to age-matched controls while TNFα and NOS2 mRNA levels, genes commonly associated with classical activation, increased or did not change, respectively. Only TNFα mRNA increased in the Tg-SwDI mouse brain. Alternative activation genes were also identified in brain samples from individuals with AD and were compared to age-matched control individuals. In AD brain, mRNAs for TNFα, AGI, MRC1 and the chitinase-3 like 1 and 2 genes (CHI3L1; CHI3L2) were significantly increased while NOS2 and IL-1β mRNAs were unchanged.

Conclusion

Immune cells within the brain display gene profiles that suggest heterogeneous, functional phenotypes that range from a pro-inflammatory, classical activation state to an alternative activation state involved in repair and extracellular matrix remodeling. Our data suggest that innate immune cells in AD may exhibit a hybrid activation state that includes characteristics of classical and alternative activation.

NO synthase 2 (NOS2) deletion promotes multiple pathologies in a mouse model of Alzheimer's disease

Alzheimer's disease is characterized by two primary pathological features: amyloid plaques and neurofibrillary tangles. The interconnection between amyloid and tau aggregates is of intense interest, but mouse models have yet to reveal a direct interrelationship. We now show that NO may be a key factor that connects amyloid and tau pathologies. Genetic removal of NO synthase 2 in mice expressing mutated amyloid precursor protein results in pathological hyperphosphorylation of mouse tau, its redistribution to the somatodendritic compartment in cortical and hippocampal neurons, and aggregate formation. Lack of NO synthase 2 in the amyloid precursor protein Swedish mutant mouse increased insoluble beta-amyloid peptide levels, neuronal degeneration, caspase-3 activation, and tau cleavage, suggesting that NO acts at a junction point between beta-amyloid peptides, caspase activation, and tau aggregation.

Activation of Toll-like Receptor 2 on Microglia Promotes Cell Uptake of Alzheimer Disease-associated Amyloid β Peptide

The human G-protein-coupled formyl peptide receptor-like 1 (FPRL1) and its mouse homologue mFPR2 mediate the chemotactic activity of a variety of polypeptides associated with inflammation and bacterial infection, including the 42-amino acid form of amyloid beta peptide (Abeta42), a pathogenic factor in Alzheimer disease. Because mFPR2 was inducible in mouse microglial cells by proinflammatory stimulants, such as bacterial lipopolysaccharide, a ligand for the Toll-like receptor 4 (TLR4), we investigated the role of TLR2 in the regulation of mFPR2. We found that a TLR2 agonist, peptidoglycan (PGN) derived from Gram-positive bacterium Staphylococcus aureus, induced considerable mFpr2 mRNA expression in a mouse microglial cell line and primary microglial cells. This was associated with a markedly increased chemotaxis of the cells in response to mFPR2 agonist peptides. In addition, activation of TLR2 markedly enhanced mFPR2-mediated uptake of Abeta42 by microglia. Studies of the mechanistic basis showed that PGN activates MAPK and IkappaBalpha, and the effect of PGN on induction of mFPR2 was dependent on signaling pathways via ERK1/2 and p38 MAPKs. The use of TLR2 on microglial cells by PGN was supported by the fact that N9 cells transfected with short interfering RNA targeting mouse TLR2 failed to show increased expression of functional mFPR2 after stimulation with PGN. Our results demonstrated a potentially important role for TLR2 in microglial cells of promoting cell responses to chemoattractants produced in lesions of inflammatory and neurodegenerative diseases in the brain.

IL-4 Inhibits the Expression of Mouse Formyl Peptide Receptor 2, a Receptor for Amyloid β1–42, in TNF-α-Activated Microglia

Microglia are phagocytic cells in the CNS and actively participate in proinflammatory responses in neurodegenerative diseases. We have previously shown that TNF-alpha up-regulated the expression of formyl peptide receptor 2 (mFPR2) in mouse microglial cells, resulting in increased chemotactic responses of such cells to mFPR2 agonists, including amyloid beta1-42 (Abeta42), a critical pathogenic agent in Alzheimer's disease. In the present study, we found that IL-4, a Th2-type cytokine, markedly inhibited TNF-alpha-induced expression of mFPR2 in microglial cells by attenuating activation of ERK and p38 MAPK as well as NF-kappaB. The effect of IL-4 was not dependent on Stat6 but rather required the protein phosphatase 2A (PP2A) as demonstrated by the capacity of PP2A small interfering RNA to reverse the effect of IL-4 in TNF-alpha-activated microglia. Since both IL-4 and TNF-alpha are produced in the CNS under pathophysiological conditions, our results suggest that IL-4 may play an important role in the maintenance of CNS homeostasis by limiting microglial activation by proinflammatory stimulants.

CpG-containing oligodeoxynucleotide promotes microglial cell uptake of amyloid beta 1-42 peptide by up-regulating the expression of the G-protein- coupled receptor mFPR2

Human G protein-coupled formyl peptide receptor like 1 (FPRL1) and its mouse homologue murine formyl peptide receptor 2 (mFPR2) mediate the chemotactic activity of amyloid beta 1-42 (Abeta42), a key pathogenic peptide in Alzheimer's disease (AD). Since mFPR2 is up-regulated in mouse microglia by lipopolysaccharide (LPS), a Toll-like receptor 4 ligand, we investigated the capacity of CpG-containing oligodeoxynucleotide (ODN), a Toll-like receptor (TLR) 9 ligand, to regulate the expression of mFPR2 in mouse microglia. CpG ODN markedly enhanced the expression and function of mFPR2 in microglial cells, which exhibited increased chemotactic responses to mFPR2 agonists, including Abeta42. The effect of CpG ODN is dependent on activation of p38 MAPK. Further studies showed that CpG ODN-treated microglia increased their capacity to endocytose Abeta42 through mFPR2, as this process was abrogated by pertussis toxin, a Gi protein inhibitor, and W peptide, another potent mFPR2 agonist. Our results suggest that TLR9 may play an important role in promoting microglial recognition of Abeta42, thus affecting the pathogenic process of AD.

Complementary contribution of CD4 and CD8 T lymphocytes to T-cell infiltration of the intact and the degenerative spinal cord

The central role of T cells in inflammatory reactions of the central nervous system (CNS) is well documented. However, there is little information about the few T cells found within the noninflamed CNS. In particular, the contribution of CD4+ and CD8+ T cells to the lymphocyte pool infiltrating the intact CNS, the location of these cells in CNS white and gray matter, and changes in the cellular composition of T-cell infiltrates coinciding with degeneration are primarily undefined. To address these points, we studied T cells in the intact and degenerative rat spinal cord. In the intact spinal cord, T cells were preferentially located within the gray matter. CD8+ T cells were more numerous than CD4+ lymphocytes. In cases of neuroaxonal degeneration or myelin degeneration/oligodendrocyte death, T cells were predominantly seen in areas of degeneration and were present in increased numbers. These effects were more pronounced for the CD4+ than for the CD8+ T-cell subset. Collectively, these data provide evidence for a clear cellular and compartmental bias in T-cell infiltration of the intact and degenerative spinal cord. This could indicate that CD4+ and CD8+ T cells might fulfill complementary roles in the intact and the diseased organ.

The presence of ascorbate induces expression of brain derived neurotrophic factor in SH-SY5Y neuroblastoma cells after peroxide insult, which is associated with increased survival

Oxidative stress and free radical production have been implicated in Alzheimer's disease, where low levels of the antioxidant vitamin C (ascorbate) have been shown to be associated with the disease. In this study, neuroblastoma SH-SY5Y cells were treated with hydrogen peroxide in the presence of ascorbate in order to elucidate the mechanism(s) of protection against oxidative stress afforded by ascorbate. Protein oxidation, glutathione levels, cell viability and the effects on the proteome and its oxidized counterpart were monitored. SH-SY5Y cells treated with ascorbate prior to co-incubation with peroxide showed increased viability in comparison to cells treated with peroxide alone. This dual treatment also caused an increase in protein carbonyl content and a decrease in glutathione levels within the cells. Proteins, extracted from SH-SY5Y cells that were treated with either ascorbate or peroxide alone or with ascorbate prior to peroxide, were separated by two-dimensional gel electrophoresis and analyzed for oxidation. Co-incubation for 24 hours decreased the number of oxidised proteins (e.g. acyl CoA oxidase 3) and induced brain derived neurotrophic factor (BDNF) expression. Enhanced expression of BDNF may contribute to the protective effects of ascorbate against oxidative stress in neuronal cells.

Sex steroids, APOE genotype and the innate immune system

Microglia are a primary cellular component of the CNS innate immune system. Their response to conserved pathogen motifs is inherent and leads to the release of cytoactive factors that impact surrounding neurons and glia. The microglial response is modified by the local tissue environment and by "global" factors such as gender. Exposure to estrogen and testosterone, in general, down regulate microglia and peripheral macrophage function, promoting an anti-inflammatory phenotype. Other global factors, however, can "override" the gender-based effects demonstrated by estrogen or testosterone. Apolipoprotein E (APOE) genotype and the expression of specific isoforms of apolipoprotein E differentially regulate microglial and peripheral macrophage function. Our studies have shown that the presence of the APOE4 gene, a known risk factor for AD and other neurodegenerative diseases, promotes a pro-inflammatory macrophage phenotype in neonatal microglia. However, in adult mice, the APOE genotype-specific effect depends on gender. Peritoneal macrophages from female adult APOE3 and APOE4 targeted replacement mice do not demonstrate an APOE genotype-specific response, whereas adult male APOE4 targeted replacement mice show enhanced macrophage responsiveness compared to adult male APOE3 mice. At least part of the altered macrophage response in APOE4 male mice may be due to differences in androgen receptor sensitivity to testosterone. These data re-enforce the concept that classical activation in macrophages has multiple levels of regulation, dictated by competing or synergistic factors and genotype.

APOE genotype-specific differences in human and mouse macrophage nitric oxide production

Individuals expressing an APOE4 genotype demonstrate increased Alzheimer's disease (AD) neuropathology and a decreased onset age. The APOE4 gene may act by modulating the CNS immune response. Using human monocyte-derived macrophages (MDM), we show a significantly greater increase in NO production during immune activation in MDM from APOE4 AD patients compared to normal, age-matched individuals or to AD patients with an APOE 3/3 genotype. Microglia and peritoneal macrophages from APOE4 targeted replacement mice demonstrate a similar increase in NO compared to the APOE3 targeted replacement mice. The enhanced macrophage responsiveness and the increased production of NO in APOE4 AD patients may predispose the CNS to an increased potential for nitration and nitrosation, consistent with the redox imbalance and neuroinflammatory state seen in AD.

Does aspirin or other NSAIDs reduce the risk of cognitive decline in elderly persons? Results from a population-based study

OBJECTIVE

To investigate the protective effect of NSAIDs and aspirin separately on cognitive decline in elderly subjects, controlling for consistent use of these agents over a prolonged period of time.

METHODS

The study sample consisted of 1007 subjects, drawn from a population-based random sample of elderly individuals, 62-85 years old, who participated in a 3-year follow-up study. From this sample subjects were selected, who did use NSAIDs and completed all cognitive tests at both measurements (n=137), and subjects who did not use NSAIDs and completed all cognitive tests (n=475). Cognitive tests included the Mini-Mental State Examination (MMSE), tests for episodic memory (Auditory Verbal Learning Test) and information processing speed (coding task). Cognitive decline was computed using Edwards-Nunnally method. Multiple logistic regression analyses were performed to examine the association between NSAID (with and without aspirin) and decline in cognitive performance. Besides, the interaction of NSAIDs with age on cognitive decline was determined.

RESULTS

The relative risk estimates of decline in episodic memory (immediate recall) adjusted for age, gender, education, baseline MMSE, vascular diseases, diabetes mellitus and (rheumatoid) arthritis for aspirin users only was more than three times reduced (OR: 0.30, 95% CI: 0.09-0.82). The odds ratio for decline in memory of NSAID use without aspirin, adjusted for age, gender, education, baseline MMSE, vascular diseases, diabetes mellitus and (rheumatoid) arthritis was not significant (OR: 1.00, 95% CI: 0.39-2.93). The effect of aspirin was significant only in persons of 75 years and over (OR: 0.10, 95% CI: 0.01-0.81), not in subjects younger than 75 years (OR: 0.52, 95% CI: 0.14-1.96). NSAIDs did not have benefit on information processing speed. In 92% of aspirin users a low dose of 100mg daily or less was used.

CONCLUSION

Low-dose aspirin might be protective for decline in memory in individuals of 75 years and over. The benefit of a low-dose aspirin does not support an anti-inflammatory effect, but suggests an antiplatelet effect. Therefore, a possible protective effect of low-dose aspirin on cognitive decline is likely only in subjects with aspirin use over a prolonged period of time.

Reciprocal interactions between microglia and neurons: from survival to neuropathology

Microglia represent a major cellular component of the brain, where they constitute a widely distributed network of immunoprotective cells. During the last decades, it has become clear that the functions traditionally ascribed to microglia, i.e. to dispose of dead cells and debris and to mediate brain inflammatory states, are only a fraction of a much wider repertoire of functions spanning from brain development to aging and neuropathology. The aim of the present survey is to critically discuss some of these functions, focusing in particular on the reciprocal microglia-neuron interactions and on the complex signaling systems subserving them. We consider first some of the functional interactions dealing with invasion, proliferation and migration of microglia as well as with the establishment of the initial blueprint of neural circuits in the developing brain. The signals related to the suppression of immunological properties of microglia by neurons in the healthy brain, and the derangement from this physiological equilibrium in aging and diseases, are then examined. Finally, we make a closer examination of the reciprocal signaling between damaged neurons and microglia and, on these bases, we propose that microglial activation, consequent to neuronal injury, is primarily aimed at neuroprotection. The loss of specific communication between damaged neurons and microglia is viewed as responsible for the turning of microglia to a hyperactivated state, which allows them to escape neuronal control and to give rise to persistent inflammation, resulting in exacerbation of neuropathology. The data surveyed here point at microglial-neuron interactions as the basis of a complex network of signals conveying messages with high information content and regulating the most important aspects of brain function. This network shares similar features with some fundamental principles governing the activity of brain circuits: it is provided with memory and it continuously evolves in relation to the flow of time and information.

Activation of microglia: a neuroinflammatory role for CAP37

Recent evidence suggests that inflammation and immune function in the central nervous system (CNS) may play a considerable role in the progression of many neurodegenerative diseases. It is known that microglia, the CNS equivalent of peripheral blood monocytes, may be instrumental in causing neurotoxicity. However, the mediator(s) that activates microglia to produce toxic substances that orchestrate cell death has yet to be elucidated. We have identified a novel inflammatory molecule, cationic antimicrobial protein of molecular weight 37 kDa (CAP37), to the brains of patients dying from Alzheimer's disease. CAP37 is known to be a potent activator and regulator of monocyte function in the systemic circulation. We hypothesize that CAP37, a mediator previously shown to recruit and activate monocytes in the systemic circulation, may also play a role in CNS inflammation by modulating microglial function. Here we demonstrate that CAP37 is a chemoattractant for microglia and that CAP37-treated microglia express class II major histocompatibility antigens and produce proinflammatory cytokines and chemokines. We conclude that CAP37 has the ability to activate microglial cells and suggest that it has the potential to serve as a neuroinflammatory molecule.

beta-Amyloid peptide induces formation of actin stress fibers through p38 mitogen-activated protein kinase

Based on the critical role of actin in the maintenance of synaptic function, we examined whether expression of familial beta-amyloid precursor protein APP-V642I (IAPP) or mutant presenilin-1 L286V (mPS1) affects actin polymerization in rat septal neuronal cells. Expression of either IAPP or mPS1 but not wild-type amyloid precursor protein or presenilin-1induced formation of actin stress fibers in SN1 cells, a septal neuronal cell line. Treatment with beta-amyloid (Abeta) peptide also caused formation of actin stress fibers in SN1 cells and primary cultured hippocampal neurons. Treatment with a gamma-secretase inhibitor completely blocked formation of actin stress fibers, indicating that overproduction of Abeta peptide induces actin stress fibers. Because activation of the p38 mitogen-activated protein kinase (p38MAPK)-mitogen-associated protein kinase-associated protein kinase (MAPKAPK)-2-heat-shock protein 27 signaling pathway mediates actin polymerization, we explored whether Abeta peptide activates p38MAPK and MAPKAPK-2. Expression of IAPP or mPS1 induced activation of p38MAPK and MAPKAPK-2. Treatment with a p38MAPK inhibitor completely inhibited formation of actin stress fibers mediated by Abeta peptide, IAPP or mPS1. Moreover, treatment with a gamma-secretase inhibitor completely blocked activation of p38MAPK and MAPKAPK-2. In summary, our data suggest that overproduction of Abeta peptide induces formation of actin stress fibers through activation of the p38MAPK signaling pathway in septal neuronal cells.

Immunological mechanisms and the spectrum of psychiatric syndromes in Alzheimer's disease

Pathological, genetic and epidemiological studies support the opinion that inflammatory mechanisms are involved in the pathogenesis of Alzheimer's disease (AD). Recent pathological and neuroradiological (PET) data show that activation of microglia is an early pathogenic event that precedes the process of severe neuropil destruction in AD brains. In this paper we review the evidence that inflammatory mediators can play a pathogenic role in some behavioural disorders frequently encountered during the clinical course in AD patients. Motivational disturbances are the most striking of the depressive symptoms in AD and can be present in a preclinical stage of the disease. Experimental animal studies and clinical trials in humans have shown that cytokines can induce similar symptoms which were described as 'sickness behaviour' or 'depressive-like' state. Delirious states are frequently observed in more advanced stages of dementia. Delirium is generally considered the result of an imbalance in neurotransmitter systems with severe deficits of the cholinergic systems. Animal studies show that pro-inflammatory cytokines, such as interleukin-1, induce a reduced activity of the cholinergic system. In AD, the release of cytokines would exacerbate any already existing disturbances in the cholinergic neurotransmission. This could explain the susceptibility of demented patients to delirium provoked by a wide variety of trivial incidents that are accompanied by an acute phase response. The data reviewed in this paper suggest that it could be worthwhile employing a neuroimmunological approach to study at molecular level the pathogenesis of a broad spectrum of behavioural disturbances common in the clinical course of AD patients.

Chronic brain inflammation results in cell loss in the entorhinal cortex and impaired LTP in perforant path-granule cell synapses

Alzheimer's disease (AD) is characterized by chronic neuroinflammation, significant temporal lobe cell loss, and dementia. We investigated the influence of chronic neuroinflammation produced by chronic infusion of lipopolysaccharide (LPS) into the fourth ventricle for 4 weeks upon the induction and maintenance of long-term potentiation (LTP) in the dentate gyrus of the hippocampus, a well-characterized model of cellular synaptic plasticity. We also examined for pyramidal cell loss within the entorhinal cortex an area of the brain that contains the cell bodies of the perforant path. The results demonstrate that chronic neuroinflammation results in the loss of pyramidal cells within layers II and III of the entorhinal cortex and a significant attenuation of LTP within the dentate gyrus. Similar changes may underlie the temporal lobe pathology and dementia associated with AD.

Neutrophils CD11b and fibroblasts PGE(2) are elevated in Alzheimer's disease

To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer's disease (AD) patients are reflected in the periphery, the expression of CD11b in peripheral blood neutrophils and the expression and activity of inflammatory markers in cultured skin fibroblasts were examined. We found significantly higher levels of CD11b in neutrophils from sporadic AD patients than in controls and this elevation was positively correlated with disease severity and progression rate of mental decline. Cultured skin fibroblasts from familial (FAD) and sporadic AD patients and from controls were immunopositive for both isoforms of cyclooxygenase with no differences between groups. In unstimulated culture, the production of prostaglandin-E2 in the medium was significantly higher in fibroblasts from sporadic AD and FAD patients than in controls, and this elevation was reverted by the addition of 25 microM of ibuprofen. Our findings provide further evidence of the presence of inflammatory and immuno-related markers in the periphery of AD patients and support those studies indicating the beneficial effects of anti-inflammatory therapy in AD.

Beta-amyloid deposition in the brains of rats chronically infused with thiorphan or lipopolysaccharide: the role of ascorbic acid in the vehicle

Beta-amyloid deposition and neuroinflammation are two important features of Alzheimer's disease (AD) that may influence its progression. Chronic infusion of lipopolysaccharide (LPS) into the rodent 4th ventricle reproduces many of the neurobiological changes seen in AD. Chronic infusion of ascorbic acid containing thiorphan, an inhibitor of the enzyme neprilysin that catabolizes beta-amyloid, into the hippocampus induces extracellular deposition of beta-amyloid fibrils. We investigated whether the combined presence of chronic neuroinflammation could exacerbate the deposition of beta-amyloid induced by thiorphan. The infusion of any solution containing ascorbic acid alone or with thiorphan or LPS increased the level of intraneuronal beta-amyloid immunoreactivity. Solutions that did not contain ascorbic acid were not associated with increased intraneuronal beta-amyloid immunoreactivity. The role of neprilysin in the deposition of beta-amyloid in AD brains remains undetermined.

Is pharmacological prevention of Alzheimer's a realistic goal?

A growing body of evidence suggests that several classes of drugs marketed for other indications may be effective in the prevention of Alzheimer's disease. Among the most promising of these are nonsteroidal anti-inflammatory agents, oestrogens (oestrogen replacement therapy) and antioxidant vitamins. Other less well-established candidates include histamine H(2) receptor antagonists (H(2) blockers) and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). For each of these, we discuss possible mechanisms for their postulated neuroprotective effects and review the studies suggesting their benefits in Alzheimer's disease. We conclude that nonsteroidal anti-inflammatory drugs and oestrogen replacement therapies may be effective in preventing Alzheimer's disease only if taken during the latent phase of the disease several years prior to the appearance of disturbances. Antioxidants may also prevent Alzheimer's disease, but unlike nonsteroidal anti-inflammatory drugs and oestrogen replacement therapies, they may continue to have beneficial effects even after the clinical onset of the disease. The only way to demonstrate the efficacy of these agents will be through randomised, controlled prevention trials. Such trials are currently underway but conclusive results may not be available for several years. Although intriguing, more studies on the neuroprotective effects of statins and H(2) blockers are needed before trials of these agents are initiated. Finally, there are other classes of pharmacological compounds emerging on the horizon, including folic acid, anti-beta-sheet conformational agents, secretase inhibitors and vaccines, that may soon prove to be effective for the prevention of Alzheimer's disease.

Early recognition of delirium: review of the literature

This review focuses on delirium and early recognition of symptoms by nurses. Delirium is a transient organic mental syndrome characterized by disturbances in consciousness, thinking and memory. The incidence in older hospitalized patients is about 25%. The causes of delirium are multi-factorial; risk factors include high age, cognitive impairment and severity of illness. The consequences of delirium include high morbidity and mortality, lengthened hospital stay and nursing home placement. Delirium develops in a short period and symptoms fluctuate, therefore nurses are in a key position to recognize symptoms. Delirium is often overlooked or misdiagnosed due to lack of knowledge and awareness in nurses and doctors. To improve early recognition of delirium, emphasis should be given to terminology, vision and knowledge regarding health in ageing and delirium as a potential medical emergency, and to instruments for systematic screening of symptoms.

Immunological aspects of microglia: relevance to Alzheimer's disease

Alzheimer's disease (AD) is a progressive dementing neurologic illness, and the most frequent cause of dementia in the elderly. Neuritic plaques are one of the main neuropathological findings in AD, and the major protein component is the beta-amyloid protein (A beta). Another striking feature of neuritic plaques is the presence of activated microglia, cytokines, and complement components, suggestive of "inflammatory foci" within AD brain. In this review, we will examine the mechanisms by which microglia become activated in AD, emphasizing the role in the A beta protein and proinflammatory cytokines. As well, pathways for suppression of microglial activation by immunosuppressive cytokines will be described. Inflammation mediated by activated microglia is an important component of AD pathophysiology, and strategies to control this response could provide new therapeutic approaches for the treatment of AD.