Granins as disease-biomarkers: translational potential for psychiatric and neurological disorders.

The identification of biomarkers represents a fundamental medical advance that can lead to an improved understanding of disease pathogenesis, and holds the potential to define surrogate diagnostic and prognostic endpoints. Because of the inherent difficulties in assessing brain function in patients and objectively identifying neurological and cognitive/emotional symptoms, future application of biomarkers to neurological and psychiatric disorders is extremely desirable. This article discusses the biomarker potential of the granin family, a group of acidic proteins present in the secretory granules of a wide variety of endocrine, neuronal and neuroendocrine cells: chromogranin A (CgA), CgB, Secretogranin II (SgII), SgIII, HISL-19 antigen, 7B2, NESP55, VGF and ProSAAS. Their relative abundance, functional significance, and secretion into the cerebrospinal fluid (CSF), saliva, and the general circulation have made granins tractable targets as biomarkers for many diseases of neuronal and endocrine origin, recently impacting diagnosis of a number of neurological and psychiatric disorders including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, frontotemporal dementia, and schizophrenia. Although research has not yet validated the clinical utility of granins as surrogate endpoints for the progression or treatment of neurological or psychiatric disease, a growing body of experimental evidence indicates that the use of granins as biomarkers might be of great potential clinical interest. Advances that further elucidate the mechanism(s) of action of granins, coupled with improvements in biomarker technology and direct clinical application, should increase the translational effectiveness of this family of proteins in disease diagnosis and drug discovery.

Role of Hypertension in Aggravating Abeta Neuropathology of AD Type and Tau-Mediated Motor Impairment.

Epidemiological evidence suggests that hypertension may accelerate the onset and progression of Alzheimer's disease (AD). In this study, we explored the role of hypertension in the neurodegenerative changes associated with Abeta and tau aggregation. We induced hypertension in APP(swe) Tg2576 and P301L-tauTg mouse models. In Tg2576 mice, experimental hypertension was associated with a significant increase of the accumulation of Amyloid-beta (Abeta) peptides in brain tissue and a significant reduction of Abeta peptides in serum (P < .05). These results indicate that hypertension may promote AD-type Abeta neuropathology in Tg2576. In P301L-tauTg mice we found that the presence of hypertension was significantly associated with aggravated motor function assessed by hindlimb extension test (P = .01). These results suggest that hypertension may play a role in accelerating the progression of motor dysfunction associated with tau-related alterations. Our studies suggest that the management of blood pressure (BP) may alleviate AD-type Abeta neuropathology and neurological disorders associated with abnormal tau metabolism.

Identification of potential CSF biomarkers in ALS.

BACKGROUND: The clinical diagnosis of ALS is based entirely on clinical features. Identification of biomarkers for ALS would be important for diagnosis and might also provide clues to pathogenesis. OBJECTIVE: To determine if there is a specific protein profile in the CSF that distinguishes patients with ALS from those with purely motor peripheral neuropathy (PN) and healthy control subjects. METHODS: CSF obtained from patients with ALS, disease controls (patients with other neurologic disorders), and normal controls were analyzed using the surface-enhanced laser desorption/ionization time-of-flight mass spectrometry proteomics technique. Biomarker sensitivity and specificity was calculated with receiver operating characteristic curve methodology. ALS biomarkers were purified and sequence identified by mass spectrometry-directed peptide sequencing. RESULTS: In initial proteomic discovery studies, three protein species (4.8-, 6.7-, and 13.4-kDa) that were significantly lower in concentration in the CSF from patients with ALS (n = 36) than in normal controls (n = 21) were identified. A combination of three protein species (the "three-protein" model) correctly identified patients with ALS with 95% accuracy, 91% sensitivity, and 97% specificity from the controls. Independent validation studies using separate cohorts of ALS (n = 13), healthy control (n = 25), and PN (n = 7) subjects confirmed the ability of the three CSF protein species to separate patients with ALS from other diseases. Protein sequence analysis identified the 13.4-kDa protein species as cystatin C and the 4.8-kDa protein species as a peptic fragment of the neurosecretory protein VGF. CONCLUSION: Additional application of a "three-protein" biomarker model to current diagnostic criteria may provide an objective biomarker pattern to help identify patients with ALS.

Inhibition of cyclooxygenase as potential novel therapeutic strategy in N141I presenilin-2 familial Alzheimer's disease.

The present study was designed to further explore the potential cause/effect relationship between the expression of both the N141I presenilin (PS)2 mutant familial Alzheimer's disease (FAD) gene and cyclooxgenase (COX) in respect to the mechanism associated with programmed cell death in Alzheimer's disease (AD). We found that expression of mutant N141I PS2 resulting in apoptotic cell death in H4 neuronal cells coincided with >4-fold induction in the expression of the inducible form of COX-2, but not the constitutive COX-1. Moreover, we found that the expression of the N141I PS2 FAD gene strongly promoted (>2-fold) glycogen synthase kinase (GSK)-3beta activity coincidental with a reduction in the level of beta-catenin translocated from the cytoplasmic to the nuclear compartment. Most interestingly, we found that inhibition of COX-2-mediated generation of prostaglandin (PG)-E2 in H4 neuronal cells with the preferential COX-2 inhibitor nimesulide protects against N141I PS2-mediated apoptotic cell death coincidental with an inhibition of GSK-3beta activity and subsequent normalization of beta-catenin cellular distribution. The clinical relevance of this finding was confirmed by the evidence that COX-2 protein and PG-E2 concentrations were selectively increased >2-fold in the cerebral cortex of subjects harboring the N141I PS2 FAD mutation relative to wild-type PS2 AD cases. This study demonstrates for the first time that COX-2 may be a downstream effector of mutant N141I PS2-mediated apoptotic cell death and that inhibition of COX-2 may neuroprotect in AD through modulation of a GSK-3beta-beta-catenin-mediated response. The study provides support for the potential pharmacogenomic identification of N141I PS2 FAD cases that might preferentially benefit from inhibition of COX-2 during the progression of clinical dementia.

Phosphorylation of tau at THR212 and SER214 in human neuronal and glial cultures: the role of AKT.

We have reported recently that the microtubule-associated protein tau is phosphorylated in vitro by Akt, an important kinase in anti-apoptotic signaling regulated by insulin and growth factors. We also established that Akt phosphorylates tau separately at T212 and S214, two sites previously shown to be phosphorylated by glycogen synthase kinase 3beta (GSK3beta) and protein kinase A (PKA), respectively. In the present studies, we examined the relationship between Akt and T212/S214 in primary cultures of human neurons and astrocytes, and evaluated the contribution of two other kinases. In intact cells, we found a very low content of active (phospho-S473) form of Akt. We also found a low content of phospho-S214 but not phospho-T212 of tau, suggesting that only phospho-S212 may depend on Akt activity in situ. We upregulated Akt activity using two experimental models: treatment with a protein phosphatase inhibitor, okadaic acid, and transfection with a constitutively active Akt gene construct (c-Akt). Under these conditions, phosphorylation of tau at T212 and S214 was regulated independently, with little change or downregulation of phospho-T212 and dynamic upregulation of phospho-S214. Our studies revealed that Akt may influence the phospho-S214 content in a meaningful manner. They also revealed that PKA may only partially contribute to the phosphorylation of S214. In comparison, okadaic acid treatment severely depleted the content of GSK3beta and downregulated the remaining GSK3beta activity by Akt-dependent inhibition, consistent with minimal changes in phospho-T212. In summary, these results strongly suggest that in primary cultures, Akt selectively phosphorylates tau at S214 rather than T212. Our studies raise the possibility that tau S214 may participate in Akt-mediated anti-apoptotic signaling.

A role of P301L tau mutant in anti-apoptotic gene expression, cell cycle and apoptosis.

In exploring the causative role of the most common Pro(301)-to-Leu (TauP301L) tau missense mutation associated with neurodegenerative tauopathies, we examined TauP301L-mediated apoptotic cell death and the expression of a cluster of genes involved in the inhibition of apoptosis (IAPs) in human neuroblastoma SH-SY5Y cells. Our research found that the expression of TauP301L, but not wild-type tau, down regulated the expression of IAPs, including survivin, which plays a role in the mitotic spindle checkpoint. The inhibition of IAPs coincided with the activation of the pro-apoptotic caspase 3, but preceded apoptotic cell death by TUNEL. Furthermore, TauP301L altered the expression of the cell cycle regulatory proteins and induced the cell cycle arrest at G(2)/M phase. Our studies demonstrate that TauP301L downregulates the expression of genes that protect against apoptosis and regulate cell cycle progression. These results suggest a novel mechanism of apoptotic cell death in TauP301L-expressing cells that involves survivin-mediated activation of cell cycle checkpoint.

High-throughput proteomics and protein biomarker discovery in an experimental model of inflammatory hyperalgesia: effects of nimesulide.

OBJECTIVE: The goal of this study was to derive a systematic approach for the identification of protein species profiles that selectively identify subgroups of similar but distinct pain models and correlate with the therapeutic efficacy (or lack thereof) of drug intervention. METHODS: Using high-throughput surface-enhanced laser desorption ionization (SELDI) mass spectrometry proteomic technology based on ProteinChip arrays, we conducted a comparative analysis of the profile of protein expression in cerebral spinal fluid (CSF) from rats exposed to either injection of complete Freund's adjuvant (CFA) [a model of inflammatory pain] or chronic constriction injury (CCI) [a model of neuropathic pain]. The CFA model was then further studied for the effects of treatment with the NSAID, nimesulide (a preferential cyclo-oxygenase [COX]-2 inhibitor). RESULTS: Among other observations, we found that the content of two metal (copper) binding protein species (2.9 and 3.2kDa) and three anionic protein species (4.0, 6.9 and 8.2kDa) were increased in the CSF of rats with inflammatory pain in a time-dependent fashion, at 7 and 14 days after CFA injection. These changes were highly selective for the CFA model, as no detectable increase in these protein biomarkers was found in the CCI neuropathic pain model. Further, we found that most of the changes in the biomarker protein species induced by the inflammatory pain were prevented by treatment with nimesulide and correlated with the antihyperalgesic effect of this drug. CONCLUSION: This study demonstrates that CSF biomarker profiles, as detected by SELDI technology, can consistently and reproducibly differentiate inflammatory from neuropathic pain, and reflect the analgesic action produced by the preferential COX-2 inhibitor, nimesulide. The characterisation and identification of these biomarkers will provide invaluable insight into the pathophysiology of pain mechanisms, in addition to further understanding of the value of nimesulide in the treatment of inflammatory pain.

A therapeutic role for cyclooxygenase-2 inhibitors in a transgenic mouse model of amyotrophic lateral sclerosis.

Recent studies indicate that the proinflammatory enzyme cyclooxygenase (COX)-2, an enzyme involved in inflammatory cascades but also normal neuronal activities, is elevated in the brain and spinal cord of amyotrophic lateral sclerosis (ALS) patients and ALS mouse model systems. On the basis of this evidence, we explored the impact of COX-2 inhibition on the onset and progression of ALS-like disease in the G93A human superoxide dismutase (SOD)1 mouse model of ALS. We found that prophylactic administration of nimesulide, a preferential COX-2 inhibitor, in the feed resulted in a significant delay in the onset of ALS type motor impairment. This delay of ALS symptomatology temporally overlapped with the inhibition of prostaglandin E2 elevation in the spinal cord of SOD1-G93A transgenic mice relative to untreated SOD1-G93A controls. This study strongly supports a role for COX-2 in the pathophysiology of ALS and provides the first experimental evidence that prophylactic treatment with COX-2 inhibitors can significantly delay the onset of motor dysfunction in the SOD1-G93A transgenic mouse model of ALS.

Altered gene expression during nimesulide-mediated inhibition of apoptotic death in human chondrocytes.

We previously found that the cyclooxygenase (COX)-2 preferential inhibitor nimesulide protects rodents' chondrocytes against apoptotic death in vitro. In the present study, we found that nimesulide also reduces staurosporine-mediated apoptotic death in human chondrocytes in vitro. Using cDNA microarrays, we explored alterations in gene expression during human chondrocytic apoptosis, and the influence of nimesulide therapy on these changes. Based on their known biologic activities, candidate gene products with altered expression were assigned to clusters of biological functions and mechanisms, and analysed for specific sets of alterations. We found that the expression of genes involved in cell proliferation is differentially regulated during staurosporine-mediated apoptotic death in human chondrocytes. Treatment with nimesulide reversed the staurosporine-mediated effects on these gene products during protection against apoptosis. The study suggests that nimesulide, in addition to its analgesic effect, may confer chondroprotection through mechanisms beyond classical COX inhibition.

Randomized pilot study of nimesulide treatment in Alzheimer's disease.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAID) may be useful in the treatment of AD. Clinical and laboratory experience with nimesulide, an NSAID with preferential cyclooxygenase-2 inhibition, suggests that it may be a good candidate for AD therapy. METHODS: This pilot study investigated the clinical feasibility of nimesulide treatment in AD. Forty persons with probable AD, most of whom were taking cholinesterase inhibitors, were enrolled in a randomized, controlled, parallel-group trial designed to assess tolerability and short-term cognitive/behavioral effects of nimesulide. In the initial 12-week double-blind phase, participants were treated with nimesulide 100 mg by mouth twice daily or matching placebo; during the second 12-week phase all participants received active drug. Participants who tolerated the drug well and perceived benefit were invited to continue open-label nimesulide treatment. RESULTS: Short-term therapy with nimesulide, compared with placebo, had no significant effect on total assessment scores of measures of cognition, clinical status, activities of daily living, affect, and behavior. Long-term therapy was well tolerated for periods exceeding 2 years. CONCLUSION: These findings support the feasibility of nimesulide therapy in AD; assessment of efficacy will require a larger, long-term treatment study.

Use of cDNA microarray in the search for molecular markers involved in the onset of Alzheimer's disease dementia.

Alzheimer's disease (AD) is the most common form of dementia, affecting as many as 4 million older persons and results from abnormal changes in the brain that most likely begin long before cognitive impairment and other clinical symptoms become apparent. Thus, efforts aimed at identifying methods of early detection and diagnosis for improving AD care might be the most appropriate strategy to initiate promising new treatments and/or prevention. We used cDNA microarray technology to investigate the sequence of changes in gene expression in brain that may take place during the transition from normal cognitive functioning through the early stages of impairment to frank AD. We examined the expression of approximately 7,000 genes in the brains of cases at the early stage of AD dementia using reference sample cases characterized by normal cognitive status. Genes that are differentially regulated in early AD cases were identified and were categorized into gene clusters based on similarities in biological functions. This analysis revealed that selected biological processes, including protein and amino acid metabolism, cytoskeleton integrity, and fatty acid metabolism, are involved in early phases of AD dementia. Most notable is the observation that selected genes involved in neurotransmitter release are differentially regulated in the brains of cases at high risk for dementia. This evidence supports the feasibility and usefulness of cDNA microarray techniques to study sequential changes of distinctive gene-expression patterns in the brain as a function of the progression of AD dementia. The study suggests new means to dissect and classify stages of AD dementia, or neuropathology, at the molecular level.

Gene expression profiling of the tau mutant (P301L) transgenic mouse brain.

To provide a global analysis of the influence of Tau neuropathology at molecular level, we used cDNA arrays representing 8832 genes to determine the mRNA expression profile in transgenic mice expressing the most common frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) Tau mutation (P301L) (Nat. Genet. (2000) 402). Genes whose expression is associated with development of neurofibrillary tangles and neuron loss in P301L mice with motor and behavioral deficits were identified. The data suggest that a major mechanism underlying P301LTau neurodegeneration primarily involved altered expression of genes contributing to inhibition of apoptosis and intracellular transport. We propose that the expression of mutated P301L may lead to select altered expression of genes which may cause neurodegeneration in FTDP-17.

Cyclooxygenase and Alzheimer's disease: implications for preventive initiatives to slow the progression of clinical dementia.

Industry and academia are devoting a tremendous amount of resources to the testing of anti-inflammatory drugs for the treatment of Alzheimer's disease (AD). This trend is the result of the growing consensus supporting the inflammatory hypothesis of AD. If anti-inflammatory strategies succeed in slowing the rate of disease progression, the impact on patients and families could be enormous. However, given the large number of candidates in the pool of anti-inflammatory drugs and given their widely divergent activities, it is essential to use methods which optimizes drug selection and study design. Pilot studies of anti-inflammatory regimens are useful in determining tolerability. However, these studies have limited value in estimating effective size since disease-modification, rather than symptomatic improvement, is the ultimate goal. Better understanding of the influence of inflammatory activity and the specific mechanisms which play an early role in the progression of the disease, will improve the likelihood of successfully identifying an effective anti-inflammatory treatment strategy. This review outlines directions in research that address possible contributions of cyclooxygenase (COX)-2, COX-1 and other inflammatory mediators to AD neurodegeneration. Finally, this article addresses potential interventions designed to control segments of classical inflammatory cascades in the brain in which cyclooxygenase is highly implicated. These considerations are critical to understand the role of cyclooxygenase in the clinical progression of AD.

Non-steroidal anti-inflammatory drugs protect against chondrocyte apoptotic death.

Recent evidence suggests that the degradation of cartilage in osteoarthritis is characterized by chondrocyte apoptosis, but little is known about the molecular mechanisms involved or potential protective measures. In the present study, we used an immortalized chondrocyte cell line to explore the mechanisms of apoptotic chondrocyte cell death. We found that staurosporine-mediated chondrocyte death depended on the concentration and time of incubation, and coincided with increased Bax:Bcl-X mRNA expression, cytochrome C release, and activation of caspase-3. Pre-treatment of the cultures with nimesulide, a preferential cyclooxygenase (COX)-2 inhibitor, or with ibuprofen, a non-selective COX-1/COX-2 inhibitor, protected the chondrocytes against the staurosporine-mediated nuclear damage and cell death in a concentration-dependent manner (10(-12) to 10(-6) M). Cell protection coincided with inhibition of the staurosporine-mediated induction of caspase-3 activation. Notably, the selective COX-2 inhibitor NS-398 (10(-6) M, 24 hr pre-treatment) did not protect the cells against staurosporine-mediated apoptotic death. The data suggest that nimesulide and ibuprofen, in addition to their anti-inflammatory and analgesic benefits, may also have a protective effect in osteoarthritis through the inhibition of apoptosis in chondrocytes.

Neuronal cyclooxygenase 2 expression in the hippocampal formation as a function of the clinical progression of Alzheimer disease.

BACKGROUND: Prior studies have shown that cyclooxygenase 2 (COX-2), an enzyme involved in inflammatory mechanisms and neuronal activities, is up-regulated in the brain with Alzheimer disease (AD) and may represent a therapeutic target for anti-inflammatory treatments. OBJECTIVE: To explore COX-2 expression in the brain as a function of clinical progression of early AD. DESIGN AND MAIN OUTCOME MEASURES: Using semiquantitative immunocytochemistry, we analyzed COX-2 protein content in the hippocampal formation in 54 postmortem brain specimens from patients with normal or impaired cognitive status. SETTING AND PATIENTS: Postmortem study of nursing home residents. RESULTS: The immunointensity of COX-2 signal in the CA3 and CA2 but not CA1 subdivisions of the pyramidal layers of the hippocampal formation of the AD brain increased as the disease progressed from questionable to mild clinical dementia as assessed by Clinical Dementia Rating. COX-2 signal was increased in all 3 regions examined among cases characterized by severe dementia. CONCLUSION: Neuronal COX-2 content in subsets of hippocampal pyramidal neurons may be an indicator of progression of dementia in early AD.

Complement anaphylatoxin C5a neuroprotects through mitogen-activated protein kinase-dependent inhibition of caspase 3.

We previously reported that pretreatment of murine cortico-hippocampal neuronal cultures with the complement-derived anaphylatoxin C5a, protects against glutamate neurotoxicity. In this study we explored the potential mechanisms involved in C5a-mediated neuroprotection. We found that C5a neuroprotects in vitro through inhibition of apoptotic death because pretreatment with human recombinant (hr)C5a prevented nuclear DNA fragmentation coincidental to inhibition of the pro-apoptotic caspase 3 activity mediated by glutamate treatment. Also, hrC5a-mediated responses appeared to be receptor-mediated because pretreatment of cultures with the specific C5a receptor antagonist C177, prevented hrC5a-mediated neuroprotection. Based on this evidence, we further explored possible signaling pathways involved in hrC5a inhibition of caspase 3 activation and apoptotic neuronal death. We found that treatment of cultures with the mitogen-activated protein kinase (MAPK) pathway inhibitor PD98059 prevented hrC5a-mediated inhibition of caspase 3 and apoptotic neuron death. MAPK pathways, whose activation by hrC5a is inhibited by PD98059 and C177, include the extracellular signal-regulated kinase (ERK)2 and, to a lesser extent, ERK1. The study suggests that C5a may protect against glutamate-induced apoptosis in neurons through MAPK-mediated regulation of caspase cascades.

Altered expression of a-type but not b-type synapsin isoform in the brain of patients at high risk for Alzheimer's disease assessed by DNA microarray technique.

Using a cDNA microarray representing 6794 distinct human genes, we identified candidate genes whose expression is altered in cerebral cortex of cases of early Alzheimer's disease (AD); among these was the synaptic vesicle protein synapsin II, which plays an important role in neurotransmitter release. While other candidate genes are presently under investigation in our lab, in this study we discuss the regulation of synapsin gene expression during the transition from normal cognitive function to early AD. We found a selective decrease in the expression of the synapsin splice variants I-III of the a-type isoform in the entorhinal (EC, BM36) but not visual cortex (VC, BM17) of cases characterized by the earliest clinically detectable stage of AD. In contrast, we found no changes in synapsin splice variant II of the b-type isoform. Alteration of synapsin expression at the earliest clinical stage of AD may suggest novel strategies for improved treatment.

From cDNA microarrays to high-throughput proteomics. Implications in the search for preventive initiatives to slow the clinical progression of Alzheimer's disease dementia.

Alzheimer's disease (AD) is the most common form of dementia, affecting as many as four million elderly people. lt results from abnormal changes in the brain that most likely begin long before cognitive impairment and other clinical symptoms become apparent. Little is known about the changes preceding or accompanying initiation of the disease. Using cDNA microarray, we previously reported candidate gene products whose expression is altered in the cerebral cortex of cases at risk for AD dementia. However, it is possible that the cDNA microarray evidence might have underestimated post-transcriptional modifications, and as a result, provided only a partial view of the biological problem of interest. Based on this hypothesis, we initiated a series of parallel high-throughput proteomic studies. We found that, consistent with the cDNA microarray evidence, the expression of proteins involved in synaptic activities was also altered in the brains of early AD cases. These studies support the feasibility and usefulness of high-throughput cDNA and protein microarray techniques to examine the sequential changes of distinctive gene expression patterns in the brain as a function of the progression of AD dementia. Our preliminary results also support the utility of high-throughput proteomic methodologies as a means to identify novel AD biomarkers from cerebral spinal fluid and/or from serum.

Cytokine gene expression as a function of the clinical progression of Alzheimer disease dementia.

BACKGROUND: Inflammatory cytokines have been linked to Alzheimer disease (AD) neurodegeneration, but little is known about the temporal control of their expression in relationship to clinical measurements of AD dementia progression. DESIGN AND MAIN OUTCOME MEASURES: We measured inflammatory cytokine messenger RNA (mRNA) expression in postmortem brain specimens of elderly subjects at different clinical stages of dementia and neuropathological dysfunction. SETTING AND PATIENTS: Postmortem study of nursing home patients. RESULTS: In brains of cognitively normal control subjects, higher interleukin 6 (IL-6) and transforming growth factor beta1 (TGF-beta1) mRNA expression was observed in the entorhinal cortex and superior temporal gyrus compared with the occipital cortex. Compared with age-matched controls, subjects with severe/terminal dementia, but not subjects at earlier disease stages, had higher IL-6 and TGF-beta1 mRNA expression in the entorhinal cortex (P<.01) and superior temporal gyrus (P<.01). When stratified by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropathological criteria, IL-6 mRNA expression in both the entorhinal cortex (P<.05) and superior temporal gyrus (P<.01) correlated with the level of neurofibrillary tangles but not neuritic plaques. However, in the entorhinal cortex, TGF-beta1 mRNA did not correlate with the level of either neurofibrillary tangles or neuritic plaques. Interestingly, in the superior temporal gyrus, TGF-beta1 mRNA expression negatively correlated with neurofibrillary tangles (P<.01) and showed no relationship to the pathological features of neuritic plaques. CONCLUSIONS: The data are consistent with the hypothesis that cytokine expression may differentially contribute to the vulnerability of independent cortical regions during the clinical progression of AD and suggest that an inflammatory cytokine response to the pathological effects of AD does not occur until the late stages of the disease. These findings have implications for the design of anti-inflammatory treatment strategies. Arch Neurol. 2000;57:1153-1160