Preserved autophagy in cognitively intact non-demented individuals with Alzheimer's neuropathology

INTRODUCTION

Growing evidence supports that dysfunctional autophagy, the major cell mechanism responsible for removing protein aggregates and a route of clearance for Tau in healthy neurons, is a major finding in demented Alzheimer's disease (AD) patients. However, the association of autophagy with maintenance of cognitive integrity in resilient individuals who have AD neuropathology but remain non-demented (NDAN) has not been evaluated.

METHODS

Using post mortem brain samples from age-matched healthy control, AD, and NDAN subjects, we evaluated autophagy in relation to Tau pathology using Western blot, immunofluorescence and RNA-seq.

RESULTS

Compared to AD patients, NDAN subjects had preserved autophagy and reduced tauopathy. Furthermore, expression of autophagy genes and AD-related proteins were significantly associated in NDAN compared to AD and control subjects.

DISCUSSION

Our results suggest preserved autophagy is a protective mechanism that maintains cognitive integrity in NDAN individuals. This novel observation supports the potential of autophagy-inducing strategies in AD therapeutics.

HIGHLIGHTS

NDAN subjects have preserved autophagic protein levels comparable with control subjects. Compared to control subjects, NDAN subjects have significantly reduced Tau oligomers and PHF Tau phosphorylation at synapses that negatively correlate with autophagy markers. Transcription of autophagy genes strongly associates with AD-related proteins in NDAN donors.

Elevated α5 integrin expression on myeloid cells in motor areas in amyotrophic lateral sclerosis is a therapeutic target

Amyotrophic lateral sclerosis (ALS) is a fatal disease affecting upper and lower motor neurons. Microglia directly interact with motor neurons and participate in the progression of ALS. Single-cell mass cytometry (CyTOF) analysis revealed prominent expression of α5 integrin in microglia and macrophages in a superoxide dismutase-1 G93A mouse model of ALS (SOD1G93A). In postmortem tissues from ALS patients with various clinical ALS phenotypes and disease duration, α5 integrin is prominent in motor pathways of the central and peripheral nervous system and in perivascular zones associated with the blood-brain barrier. In SOD1G93A mice, administration of a monoclonal antibody against α5 integrin increased survival compared to an isotype control and improved motor function on behavioral testing. Together, these findings in mice and in humans suggest that α5 integrin is a potential therapeutic target in ALS.

Targeted Transcriptional Analysis of IgA Vasculitis, IgA Nephropathy, and IgA-Dominant Infection-Related Glomerulonephritis Reveals Both Distinct and Overlapping Immune Signatures

Key Points

Skin IL-9, calprotectin, and KIR gene expression may be predictive of subsequent kidney involvement in patients with IgAV. Histologically similar patients with IgAN, IgAV, and IgA-IRGN can be distinguished by their immune transcriptomes. Kidney biopsies from patients with IgA-IRGN are enriched for transcripts involved in granulocyte chemotaxis.

Background

IgA vasculitis (IgAV), IgA nephropathy (IgAN), and IgA-dominant infection-related glomerulonephritis (IgA-IRGN) have shared histopathologic features, but differences in clinical management and prognosis. The most serious IgAV organ involvement is in the kidneys (IgAV nephritis). In this study, we hypothesized that targeted immune transcript profiling could aid in (1 ) predicting the development of IgAV nephritis in patients with cutaneous IgAV and (2 ) differentiating IgAN, IgAV, and IgA-IRGN.

Methods

RNA was extracted from 24 formalin-fixed paraffin-embedded tissue specimens (16 kidney, 8 skin) from 21 patients with IgAV nephritis (n=7), IgAN (n=5), and IgA-IRGN (n=4), and IgAV skin biopsies from patients with (n=3) and without (n=5) IgAV nephritis. Differential gene expression and gene set enrichment analysis were performed on a total of 594 transcripts (Nanostring immunology panel) profiled using the nCounter system.

Results

Skin biopsies in patients with IgAV who develop kidney involvement exhibit reduced S100A8/S100A9 , IL9 , and killer cell immunoglobulin-like receptor expression. The kidney tissue immune transcriptomes of IgAN, IgAV, and IgA-IRGN are largely overlapping. IgA-IRGN kidney biopsies are, however, uniquely enriched for transcripts involved in granulocyte chemotaxis.

Conclusion

This study identifies immune transcript signatures that may predict IgAV nephritis in skin biopsies and distinguish IgA-IRGN from IgAN and IgAV in kidney biopsies.

TREM2-induced activation of microglia contributes to synaptic integrity in cognitively intact aged individuals with Alzheimer's neuropathology

The existence of individuals who remain cognitively intact despite presenting histopathological signs of Alzheimer's disease (AD), here referred to as "Nondemented with AD neuropathology" (NDAN), suggests that some mechanisms are triggered to resist cognitive impairment. Exposed phosphatidylserine (ePS) represents a neuronal "eat-me" signal involved in microglial-mediated phagocytosis of damaged synapses. A possible mediator of this process is TREM2, a microglial surface receptor activated by ligands including PS. Based on TREM2 role in the scavenging function of microglia, we hypothesize that an efficient microglial phagocytosis of damaged synapses underlies synaptic resilience in NDAN, thus protecting from memory deficits. Using immunofluorescence microscopy, we performed a comparative study of human post-mortem frontal cortices of aged-matched, AD and NDAN individuals. We studied the distribution of activated microglia (IBA1, IBA1+ /CD68+ cells) and phagocytic microglia-related proteins (TREM2, DAP12), demonstrating higher microglial activation and TREM2 expression in NDAN versus AD. A study of the preservation of synapses around plaques, assessed using MAP2 and βIII tubulin as dendritic and axonal markers, respectively, and PSD95 as a postsynaptic marker, revealed preserved axonal/dendritic structure around plaques in NDAN versus AD. Moreover, high levels of PSD95 around NDAN plaques and the colocalization of PSD95 with CD68 indicated a prompt removal of damaged synapses by phagocytic microglia. Furthermore, Annexin V assay on aged-matched, AD and NDAN individuals synaptosomes revealed increased levels of ePS in NDAN, confirming damaged synapses engulfment. Our results suggest a higher efficiency of TREM2-induced phagocytic microglia in removing damaged synapses, underlying synaptic resilience in NDAN individuals.

Neuroinflammatory Disease Responsive to MEK-Inhibitor

Objective

Illustrate that some neuroinflammatory diseases may respond best to antiproliferative therapies rather than immunomodulatory therapies.

Background

Genomics are increasingly employed in the diagnostic armamentarium of refractory neuro-inflammatory diseases. Metagenomic next-generation sequencing is used to detect pathogens and germline genetic testing is used to detect inborn errors of the immune system. Genetic testing of tissue can identify somatic mutations for targeted treatment. MEK-inhibitors are an emerging treatment for RAS/MAPK pathway mutated diseases which include some neuro-inflammatory mimics like neuro-histiocytoses.

Design/Methods

NA.

Results

Previously healthy 12-year-old girl presented with 1 month of diplopia and headaches. Her brother has clinically diagnosed NF1 (café-au-lait macules, cutaneous neurofibromas). Exam notable for right third nerve palsy. MRI showed T2/FLAIR hyperintense lesions of the right temporal lobe, basal ganglia, and cervical through thoracic cord, nodular leptomeningeal enhancement along the entire spinal cord, and right middle cerebral artery vessel wall enhancement. CSF: WBC 6/mm3(62% lymphocytes 37% monocytes), protein 133 mg/dL. She improved with pulse methylprednisolone and maintenance steroids. At 5 months, she developed malignant elevated intracranial pressure with CSF OP >50 cm water, bradycardia, and encephalopathy requiring weekly LPs. Brain biopsy showed astrocytic and microglial activation without significant inflammation. No histiocytes were noted. There was no evidence of neoplasia or infection. She was tried on anakinra. At 6 months, she developed left third nerve palsy and seizures. For weeks, she required daily LPs for intracranial hypertension despite placement of ventriculoperitoneal shunt. Additional treatments included infliximab, steroids, and siltuximab. NGS from brain biopsy identified 2 NF1 mutations (nonsense, splicing). Allele fractions: 6% and 9%. Her mental status and need for frequent LP improved dramatically with trametinib.

Conclusions

This case illustrates the importance of considering somatic genomic testing of neural tissue even when the neuropathology is not suggestive of a malignancy or histiocytosis as this can inform newer molecularly targeted therapeutic options.

Loss of perivascular aquaporin-4 localization impairs glymphatic exchange and promotes amyloid β plaque formation in mice

BACKGROUND

Slowed clearance of amyloid β (Aβ) is believed to underlie the development of Aβ plaques that characterize Alzheimer's disease (AD). Aβ is cleared in part by the glymphatic system, a brain-wide network of perivascular pathways that supports the exchange of cerebrospinal and brain interstitial fluid. Glymphatic clearance, or perivascular CSF-interstitial fluid exchange, is dependent on the astroglial water channel aquaporin-4 (AQP4) as deletion of Aqp4 in mice slows perivascular exchange, impairs Aβ clearance, and promotes Aβ plaque formation.

METHODS

To define the role of AQP4 in human AD, we evaluated AQP4 expression and localization in a human post mortem case series. We then used the α-syntrophin (Snta1) knockout mouse model which lacks perivascular AQP4 localization to evaluate the effect that loss of perivascular AQP4 localization has on glymphatic CSF tracer distribution. Lastly, we crossed this line into a mouse model of amyloidosis (Tg2576 mice) to evaluate the effect of AQP4 localization on amyloid β levels.

RESULTS

In the post mortem case series, we observed that the perivascular localization of AQP4 is reduced in frontal cortical gray matter of subjects with AD compared to cognitively intact subjects. This decline in perivascular AQP4 localization was associated with increasing Aβ and neurofibrillary pathological burden, and with cognitive decline prior to dementia onset. In rodent studies, Snta1 gene deletion slowed CSF tracer influx and interstitial tracer efflux from the mouse brain and increased amyloid β levels.

CONCLUSIONS

These findings suggest that the loss of perivascular AQP4 localization may contribute to the development of AD pathology in human populations.

Differential protein expression in the hippocampi of resilient individuals identified by digital spatial profiling

Clinical symptoms correlate with underlying neurodegenerative changes in the vast majority of people. However, an intriguing group of individuals demonstrate neuropathologic changes consistent with Alzheimer disease (AD) yet remain cognitively normal (termed “resilient”). Previous studies have reported less overall neuronal loss, less gliosis, and fewer comorbidities in these individuals. Herein, NanoString GeoMx™ Digital Spatial Profiler (DSP) technology was utilized to investigate protein expression differences comparing individuals with dementia and AD neuropathologic change to resilient individuals. DSP allows for spatial analysis of protein expression in multiple regions of interest (ROIs) on formalin-fixed paraffin-embedded sections. ROIs in this analysis were hippocampal neurofibrillary tangle (NFT)-bearing neurons, non-NFT-bearing neurons, and their immediate neuronal microenvironments. Analyses of 86 proteins associated with CNS cell-typing or known neurodegenerative changes in 168 ROIs from 14 individuals identified 11 proteins displaying differential expression in NFT-bearing neurons of the resilient when compared to the demented (including APP, IDH1, CD68, GFAP, SYP and Histone H3). In addition, IDH1, CD68, and SYP were differentially expressed in the environment of NFT-bearing neurons when comparing resilient to demented. IDH1 (which is upregulated under energetic and oxidative stress) and PINK1 (which is upregulated in response to mitochondrial dysfunction and oxidative stress) both displayed lower expression in the environment of NFT-bearing neurons in the resilient. Therefore, the resilient display less evidence of energetic and oxidative stress. Synaptophysin (SYP) was increased in the resilient, which likely indicates better maintenance of synapses and synaptic connections. Furthermore, neurofilament light chain (NEFL) and ubiquitin c-terminal hydrolase (Park5) were higher in the resilient in the environment of NFTs. These differences all suggest healthier intact axons, dendrites and synapses in the resilient. In conclusion, resilient individuals display protein expression patterns suggestive of an environment containing less energetic and oxidative stress, which in turn results in maintenance of neurons and their synaptic connections.

MRI characteristics of Japanese macaque encephalomyelitis: Comparison to human diseases

BACKGROUND AND PURPOSE

To describe MRI findings in Japanese macaque encephalomyelitis (JME) with emphasis on lesion characteristics, lesion evolution, normal-appearing brain tissue, and similarities to human demyelinating disease.

METHODS

MRI data were obtained from 114 Japanese macaques, 30 presenting neurological signs of JME. All animals were screened for presence of T2 -weighted white matter signal hyperintensities; animals with behavioral signs of JME were additionally screened for contrast-enhancing lesions. Whole-brain quantitative T1 maps were collected, and histogram analysis was performed with regression across age to evaluate microstructural changes in normal appearing brain tissue in JME and neurologically normal animals. Quantitative estimates of blood-brain-barrier (BBB) permeability to gadolinium-based-contrast agent (GBCA) were obtained in acute, GBCA-enhancing lesions. Longitudinal imaging data were acquired for 15 JME animals.

RESULTS

One hundred and seventy-three focal GBCA-enhancing lesions were identified in 30 animals demonstrating behavioral signs of neurological dysfunction. JME GBCA-enhancing lesions were typically focal and ovoid, demonstrating highest BBB GBCA permeability in the lesion core, similar to acute, focal multiple sclerosis lesions. New GBCA-enhancing lesions arose rapidly from normal-appearing tissue, and BBB permeability remained elevated for weeks. T1 values in normal-appearing tissue were significantly associated with age, but not with sex or disease.

CONCLUSIONS

Intense, focal neuroinflammation is a key MRI finding in JME. Several features of JME compare directly to human inflammatory demyelinating diseases. Investigation of JME combined with the development and validation of noninvasive imaging biomarkers offers substantial potential to improve diagnostic specificity and contribute to the understanding of human demyelinating diseases.

Oxidative Damage and Antioxidant Response in Frontal Cortex of Demented and Nondemented Individuals with Alzheimer's Neuropathology

Alzheimer's disease (AD) is characterized by progressive neurodegeneration in the cerebral cortex, histopathologically hallmarked by amyloid β (Aβ) extracellular plaques and intracellular neurofibrillary tangles, constituted by hyperphosphorylated tau protein. Correlation between these pathologic features and dementia has been challenged by the emergence of "nondemented with Alzheimer's neuropathology" (NDAN) individuals, cognitively intact despite displaying pathologic features of AD. The existence of these subjects suggests that some unknown mechanisms are triggered to resist Aβ-mediated detrimental events. Aβ accumulation affects mitochondrial redox balance, increasing oxidative stress status, which in turn is proposed as a primary culprit in AD pathogenesis. To clarify the relationship linking Aβ, oxidative stress, and cognitive impairment, we performed a comparative study on AD, NDAN, and aged-matched human postmortem frontal cortices of either sex. We quantitatively analyzed immunofluorescence distribution of oxidative damage markers, and of SOD2 (superoxide dismutase 2), PGC1α [peroxisome proliferator-activated receptor (PPAR) γ-coactivator 1α], PPARα, and catalase as key factors in antioxidant response, as well as the expression of miRNA-485, as a PGC1α upstream regulator. Our results confirm dramatic redox imbalance, associated with impaired antioxidant defenses in AD brain. By contrast, NDAN individuals display low oxidative damage, which is associated with high levels of scavenging systems, possibly resulting from a lack of PGC1α miRNA-485-related inhibition. Comparative analyses in neurons and astrocytes further highlighted cell-specific mechanisms to counteract redox imbalance. Overall, our data emphasize the importance of transcriptional and post-transcriptional regulation of antioxidant response in AD. This suggests that an efficient PGC1α-dependent "safety mechanism" may prevent Aβ-mediated oxidative stress, supporting neuroprotective therapies aimed at ameliorating defects in antioxidant response pathways in AD patients.

Distinguishing Extravascular from Intravascular Ferumoxytol Pools within the Brain: Proof of Concept in Patients with Treated Glioblastoma

BACKGROUND AND PURPOSE

Glioblastoma-associated macrophages are a major constituent of the immune response to therapy and are known to engulf the iron-based MR imaging contrast agent, ferumoxytol. Current ferumoxytol MR imaging techniques for localizing macrophages are confounded by contaminating intravascular signal. The aim of this study was to assess the utility of a newly developed MR imaging technique, segregation and extravascular localization of ferumoxytol imaging, for differentiating extravascular-from-intravascular ferumoxytol contrast signal at a delayed 24-hour imaging time point.

MATERIALS AND METHODS

Twenty-three patients with suspected post-chemoradiotherapy glioblastoma progression underwent ferumoxytol-enhanced SWI. Segregation and extravascular localization of ferumoxytol imaging maps were generated as the voxelwise difference of the delayed (24 hours) from the early (immediately after administration) time point SWI maps. Continuous segregation and extravascular localization of ferumoxytol imaging map values were separated into positive and negative components. Image-guided biologic correlation was performed.

RESULTS

Negative segregation and extravascular localization of ferumoxytol imaging values correlated with early and delayed time point SWI values, demonstrating that intravascular signal detected in the early time point persists into the delayed time point. Positive segregation and extravascular localization of ferumoxytol imaging values correlated only with delayed time point SWI values, suggesting successful detection of the newly developed extravascular signal.

CONCLUSIONS

Segregation and extravascular localization of ferumoxytol MR imaging improves on current techniques by eliminating intrinsic tissue and intravascular ferumoxytol signal and may inform glioblastoma outcomes by serving as a more specific metric of macrophage content compared with uncorrected T1 and SWI techniques.

Targeted Assessment of Enlargement of the Perivascular Space in Alzheimer's Disease and Vascular Dementia Subtypes Implicates Astroglial Involvement Specific to Alzheimer's Disease

Waste clearance from the brain parenchyma occurs along perivascular pathways. Enlargement of the perivascular space (ePVS) is associated with pathologic features of Alzheimer's disease (AD), although the mechanisms and implications of this dilation are unclear. Fluid exchange along the cerebral vasculature is dependent on the perivascular astrocytic water channel aquaporin-4 (AQP4) and loss of perivascular AQP4 localization is found in AD. We directly measured ePVS in postmortem samples of pathologically characterized tissue from participants who were cognitively intact or had AD or mixed dementia (vascular lesions with AD). We found that both AD and mixed dementia groups had significantly increased ePVS compared to cognitively intact subjects. In addition, we found increased global AQP4 expression of the AD group over both control and mixed dementia groups and a qualitative reduction in perivascular localization of AQP4 in the AD group. Among these cases, increasing ePVS burden was associated with the presence of tau and amyloid-β pathology. These findings are consistent with the existing evidence of ePVS in AD and provide novel information regarding differences in AD and vascular dementia and the potential role of astroglial pathology in ePVS.

TMOD-10. PRE-CLINICAL IMAGING MODEL OF GLIOBLASTOMA PSEUDOPROGRESSION USING DUAL FERUMOXYTOL AND GADOLINIUM CONTRAST ENHANCED MAGNETIC RESONANCE IMAGING

BACKGROUND

Temozolomide-based chemoradiotherapy (CRT) mediated neuroinflammation (pseudoprogression; Psp) within glioblastoma (GBM) is manifested by progressive gadolinium enhancement on magnetic resonance imaging (Gd-MRI)1. Unfortunately, Gd-MRI cannot reliably differentiate Psp from growing GBM. Macrophage infiltration is a prominent component of Psp, and can be noninvasively assessed by 24 hour delayed ferumoxytol-enhanced MRI (Fe-MRI)2. We have demonstrated that dual Fe- to Gd-contrast mismatch ratio may be a specific metric for identifying Psp3. The purpose of our study was to develop and characterize a preclinical model that specifically replicates the imaging context of macrophage mediated Psp.

METHODS

Athymic rats bearing intracerebral patient derived xenografts (GBM-39 and GSC-827) or U-87 GBM cells were randomized to; 1) untreated control (N= 5), 2) CRT only (irradiation [5 Gy] and temozolomide [20 mg/kg, PO] (N=4), or 3) CRT with Amphotericin B (Amp B) (0.2 mg/kg, IP QD x 3–7 days) (N=8)4. Three day post-therapeutic Fe- (ferumoxytol, 25 mg/kg IV) and Gd-MRI was performed as well as 7 day post-therapy Gd-MRI (N=7). Semi-automated enhancement segmentation and volume calculation was performed with Horos software5. Significance was evaluated using Students T-test with unequal variances.

RESULTS

The ratio of Fe- to Gd-enhancement volume 3 days after therapy was found to be significantly elevated within the CRT with Amp B group (1.7 ± 0.53) when compared to the CRT alone (0.62 ± 0.11) and control groups (0.43 ± 0.11); P< 0.01. Seven days after therapy, Gd-enhancement volume was significantly decreased within the CRT with Amp B group (0.87 ± 0.13) when compared to CRT alone (0.38 ± 0.04; P< 0.01), confirming treatment efficacy.

CONCLUSION

Preliminary results suggest that CRT combined with Amp B in this rat model replicates the imaging characteristics of human Psp and may result in improved efficacy3. Fe-MRI enhancement may capture the efficacious macrophage modulatory effects of Amp B.

Postsynaptic Proteome of Non-Demented Individuals with Alzheimer's Disease Neuropathology

Some individuals, here referred to as Non-Demented with Alzheimer’s Neuropathology (NDAN), retain their cognitive function despite the presence of amyloid plaques and tau tangles typical of symptomatic Alzheimer’s disease (AD). In NDAN, unlike AD, toxic amyloid-β oligomers do not localize to the postsynaptic densities (PSDs). Synaptic resistance to amyloid-β in NDAN may thus enable these individuals to remain cognitively intact despite the AD-like pathology. The mechanism(s) responsible for this resistance remains unresolved and understanding such protective biological processes could reveal novel targets for the development of effective treatments for AD. The present study uses a proteomic approach to compare the hippocampal postsynaptic densities of NDAN, AD, and healthy age-matched persons to identify protein signatures characteristic for these groups. Subcellular fractionation followed by 2D gel electrophoresis and mass spectrometry were used to analyze the PSDs. We describe fifteen proteins which comprise the unique proteomic signature of NDAN PSDs, thus setting them apart from control subjects and AD patients.

Silent somatotroph pituitary adenomas: an update

Silent growth hormone adenomas (SGHA) are a rare entity of non-functioning pituitary neuroendocrine tumors. Diagnosis is invariably made post-operatively of a tumor immunopositive for GH (and Pit-1 in selected cases) but without clinical acromegaly. Mainly young females are affected, and tumors are often uncovered by investigation for headaches or oligoamenorrhea. Integration of clinical, pathological and biochemical data is required for proper diagnosis. Beside normal IGF-1 levels, a third of SGHAs displays elevated GH levels and some will eventually progress to acromegaly. Almost two-thirds will be mixed GH-prolactin tumors and sparsely-granulated monohormonal GH tumors seems the more aggressive subtype. Recurrence and need for radiation is higher than other non-functioning tumors so close follow-up is warranted.

Sex differences in the association of alcohol with cognitive decline and brain pathology in a cohort of octogenarians

RATIONALE

The beneficial effects of moderate alcohol may differ in aging men versus women.

OBJECTIVES

Cognitive and functional decline and neuropathology were investigated in a cohort of aging men and women with diverse alcohol histories.

METHODS

Non-demented (Clinical Dementia Rating (CDR) of ≤ 0.5 and a Mini-Mental State Examination (MMSE) score of > 24), autonomously living participants were tracked in longitudinal aging studies to examine self-report and objective tests of rates of decline in a cohort (n = 486) of octogenarians. Neurofibrillary tangles (NFTs; Braak stage) and neuritic plaques (NPs) were staged at autopsy in a subset of participants (n = 149) using current standard neuropathologic diagnostic criteria.

RESULTS

Moderate drinking men had an attenuated rate of decline compared to rare/never drinkers and women on the MMSE and CDR sum of boxes. In contrast, moderate drinking women had a reduced rate of decline only in the Logical Memory Delayed Recall Test (LMDR) compared to rare/never drinkers and men. Moderate alcohol consumption was associated with a reduction in the incidence of advanced (stages 5-6) Braak NFT stage in men (p < 0.05), with no effect in women.

CONCLUSIONS

In this cohort, men experienced a broader range of beneficial effects associated with alcohol. Alcohol's effects may differ in men and women in important ways that suggest a narrower beneficial window.

Abstract WP411: Identification and Characterization of Human Meningeal Lymphatics

Late onset Alzheimer’s Disease (AD) is the most common form of dementia, affecting 40 million patients and countless families worldwide. AD is characterized by accumulation of amyloid beta (Aß) in the brain and central nervous system (CNS). A growing body of evidence indicates that while Aß production is unchanged, its clearance from the CNS is attenuated in late onset AD. Therefore, it is critical to determine how Aβ is cleared from the brain and if these processes differ in healthy and AD patients. Recently, two groups independently reported that a network of meningeal lymphatic vasculature participates in the clearance of solutes and macromolecules from the brain and cerebrospinal fluid of mice. However the presence of meningeal lymphatic vessels and their potential role in the clearance of Aß has not yet been defined in humans. Therefore, to determine if human meningeal lymphatic vessels absorb Aβ, we used immunofluorescence to examine superior sagittal sinus-associated dura mater tissue in a cohort of 21 patient samples including 6 subjects with no diagnosed dementia (control), 7 subjects with histopathologically confirmed AD, and 8 with diagnosis of mixed or other dementia. We found podoplanin (PDPN) positive, lumenized vessels in 19/21 patient samples, with 5/6 in control patients, 7/7 in AD patients and 7/8 in other or mixed dementia patients. These vessels were located in the dura mater, lateral to the superior sagittal sinus, and ranged from approximately 10 to 500 microns in diameter. Trace Aβ immunoreactivity was colocalized with podoplanin-positive vessels in 1/5 control, 1/7 AD, and 1/7 other or mixed dementia patients. Aß reactivity was found in meningeal blood vessels of 0/6 control, 1/7 AD, and 0/7 other or mixed dementia patients. To our knowledge, these data are the first to robustly support the existence of lymphatic vasculature in the human meninges. The data further suggest that Aß does not appear to widely deposit along wither these meningeal lymphatic or blood vessels, even among AD subjects.

Tau oligomers in cerebrospinal fluid in Alzheimer's disease

OBJECTIVE

With an increasing incidence of Alzheimer's disease (AD) and neurodegenerative tauopathies, there is an urgent need to develop reliable biomarkers for the diagnosis and monitoring of the disease, such as the recently discovered toxic tau oligomers. Here, we aimed to demonstrate the presence of tau oligomers in the cerebrospinal fluid (CSF) of patients with cognitive deficits, and to determine whether tau oligomers could serve as a potential biomarker for AD.

METHODS

A multicentric collaborative study involving a double-blinded analysis with a total of 98 subjects with moderate to severe AD (N = 41), mild AD (N = 31), and nondemented control subjects (N = 26), and two pilot studies of 33 total patients with AD (N = 19) and control (N = 14) subjects were performed. We carried out biochemical assays to measure oligomeric tau from CSF of these patients with various degrees of cognitive impairment as well as cognitively normal controls.

RESULTS

Using a highly reproducible indirect ELISA method, we found elevated levels of tau oligomers in AD patients compared to age-matched controls. Western blot analysis confirmed the presence of oligomeric forms of tau in CSF. In addition, the ratio of oligomeric to total tau increased in the order: moderate to severe AD, mild AD, and controls.

CONCLUSION

These assays are suitable for the analysis of human CSF samples. These results here suggest that CSF tau oligomer measurements could be optimized and added to the panel of CSF biomarkers for the accurate and early detection of AD.

Abstract A08: IGF1R as a key target in high risk, metastatic medulloblastoma

The risk or presence of metastasis in childhood medulloblastoma represents a substantial cause of morbidity and mortality. Relatively little has been known about the molecular mechanisms of medulloblastoma dissemination throughout the cerebrospinal axis. To determine potential interventions that address both metastasis and tumor growth, we examined the expression of cytokines and growth factors in the CSF of metastatic medulloblastoma patients that were also present in the conditioned media of metastatic, MYC amplified medulloblastoma cell lines and/or cell culture models of the leptomeninges. The presence of IGF1, the IGF-sequestering protein Igfbp3, which can be cleaved by metal metalloproteases (MMP) and the serine protease tPA, and the presence of corresponding protease modulators TIMP1 and SerpinE1/PAI-1, led us to explore the bioactivity of IGF1 in medulloblastoma. IGF1 led not only to receptor phosphorylation but also increased migration and increased relative cell growth. A tumor cell viability screen of 60 clinically-related compounds prioritized IGF1R inhibitors. Our findings support a model whereby medulloblastoma tumor cells actively migrate, rather than arrive passively, to the leptomeningeal cell surface and provide a rationale for exploring IGF1R as a target for therapeutics in future clinical trials.

Citation Format: Matthew N. Svalina, Ken Kikuchi, Jinu Abraham, Sangeet Lal, Monika A. Davare, Jennifer L. Peckham, Yoon-Jae Cho, Melanie Jackson, Daniel J. Guillaume, Nathan R. Selden, Darell D. Bigner, Kellie J. Nazemi, Sarah C. Green, Christopher L. Corless, Sakir Gultekin, Brian P. Rubin, Randall Woltjer, Charles Keller. IGF1R as a key target in high risk, metastatic medulloblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A08.

Neuropathologic basis of white matter hyperintensity accumulation with advanced age

OBJECTIVE

To determine which vascular pathology measure most strongly correlates with white matter hyperintensity (WMH) accumulation over time, and whether Alzheimer disease (AD) neuropathology correlates with WMH accumulation.

METHODS

Sixty-six older persons longitudinally followed as part of an aging study were included for having an autopsy and >1 MRI scan, with last MRI scan within 36 months of death. Mixed-effects models were used to examine the associations between longitudinal WMH accumulation and the following neuropathologic measures: myelin pallor, arteriolosclerosis, microvascular disease, microinfarcts, lacunar infarcts, large-vessel infarcts, atherosclerosis, neurofibrillary tangle rating, and neuritic plaque score. Each measure was included one at a time in the model, adjusted for duration of follow-up and age at death. A final model included measures showing an association with p < 0.1.

RESULTS

Mean age at death was 94.5 years (5.5 SD). In the final mixed-effects models, arteriolosclerosis, myelin pallor, and Braak score remained significantly associated with increased WMH accumulation over time. In post hoc analysis, we found that those with Braak score 5 or 6 were more likely to also have high atherosclerosis present compared with those with Braak score 1 or 2 (p = 0.003).

CONCLUSION

Accumulating white matter changes in advanced age are likely driven by small-vessel ischemic disease. Additionally, these results suggest a link between AD pathology and white matter integrity disruption. This may be due to wallerian degeneration secondary to neurodegenerative changes. Alternatively, a shared mechanism, for example ischemia, may lead to both vascular brain injury and neurodegenerative changes of AD. The observed correlation between atherosclerosis and AD pathology supports the latter.

Neuropathologic basis of age-associated brain atrophy

IMPORTANCE

While brain volume changes are used as surrogate markers for Alzheimer disease neuropathology in clinical studies, the extent to which these changes are due to pathologic features of Alzheimer disease in the aging brain is not well established. This study aims to clarify the neuropathologic correlates of longitudinal brain atrophy.

OBJECTIVE

To examine the association between brain atrophy during life and neuropathology in an elderly population.

DESIGN

Autopsy study of a cohort of elderly individuals.

SETTING

Community-based population.

PARTICIPANTS

Seventy-one healthy elderly individuals were selected from participants of the Oregon Brain Aging Study for having an autopsy, more than 1 magnetic resonance imaging scan, and the last magnetic resonance imaging scan within 36 months of death.

MAIN OUTCOMES AND MEASURES

The associations between brain volume trajectories (ventricular, total brain, and hippocampal) and time interaction terms for neurofibrillary tangles, neuritic plaques, gross infarcts, microinfarcts, amyloid angiopathy, Lewy bodies, APOE ε4 presence, and clinical diagnosis (no cognitive impairment, mild cognitive impairment, or dementia as time-varying covariates) were examined in mixed-effects models, adjusting for duration of follow-up and age at death.

RESULTS

Ventricular volume trajectory was significantly associated with age, presence of infarcts, neurofibrillary tangle and neuritic plaque scores, APOE ε4 allele presence, and dementia diagnosis. Total brain volume trajectory was significantly associated with age and mild cognitive impairment diagnosis. Hippocampal volume trajectory was significantly associated with amyloid angiopathy.

CONCLUSIONS AND RELEVANCE

Ventricular volume trajectory is more sensitive than total brain and hippocampal volume trajectories as a marker of accruing Alzheimer disease and vascular pathology in elderly individuals. The association between brain volume trajectories and cognitive impairment (mild cognitive impairment and dementia) remained after controlling for the degree of neuropathology and other covariates. This suggests that there may be other factors not measured in this study that could be contributing to brain atrophy in those with cognitive impairment.

Abstract 1679: Combined efficacy of Cediranib and Quinacrine in glioma is enhanced by hypoxia and is associated with autophagic vacuole accumulation

Despite robust vascularity of malignant gliomas, anti-angiogenic therapy largely fails to induce durable responses. We have previously reported that efficacy with Cediranib (Ced), a VEGF/PDGF receptor tyrosine kinase inhibitor, is synergistically enhanced via combination with late-stage autophagy inhibitor quinacrine (Quin), in intracranial 4C8 mouse glioma, resulting in decreased tumor vascularization and growth, increased tumor necrosis and improved mouse survival (#1905, AACR 2012). Our present study was aimed at investigating the role of autophagy (a cellular catabolic pathway that promotes tumor cell survival under hypoxic/nutrient stress), in this synergistic efficacy. MTS assays revealed dose-dependent reductions in cell viability for Ced and Quin under normal (Nrm) and hypoxic (0.5%O2, Hyp) conditions: IC50s(μM) under Nrm and Hyp were 2.7±0.1 and 2.4±0.2 for Ced, and 3.2±0.2 and 2.4±0.04 for Quin, respectively. Greater than additive combined efficacy for Ced+Quin occurred only under Hyp (cell viability reductions for 1μM C + 2.5μM Q: 78±7%(Hyp) vs. 31±3%(Nrm), p&lt;0.05). Western blotting for cleaved caspase 3 also indicated a marked increase in apoptosis with Ced+Quin/Hyp versus all other groups. Western blotting for autophagic vacuole (AV) associated LC3-II protein, which increases with increased autophagic flux and/or late stage autophagic inhibition, not only indicated increases with Quin, but also with Ced, suggesting that Ced may increase autophagic flux. Hypoxia potentiated LC3-II increases in the presence of either Quin or Ced, with the largest increases occurring with Ced+Quin/Hyp, suggesting that hypoxia-induced autophagic flux stimulation combined with late stage autophagic inhibition can trigger AV accumulation and cell death. Bafilomycin A1 (Baf), another late-stage autophagy inhibitor, also decreased cell viability. However, the efficacy of combined Baf and Ced was only additive and lacked substantial potentiation by Hyp (cell viability reductions for 1μM Ced/5ηM Baf: 54±8% (Hyp) vs 37±11% (Nrm)). LC3-II accumulation with Baf was substantially lower than with Quin, either with Hyp or Nrm, suggesting that in addition to inhibiting late-stage autophagy, Quin may also stimulate autophagic flux, consistent with its reported inhibition of PI3K/Akt/mTOR signaling. Thus, a key role for AV accumulation is consistent with its increase with Quin versus Baf in tandem with the improved efficacy of Quin over Baf, in combination with Ced. Our results suggest that the unique cytotoxic efficacy of Ced+Quin we previously reported in vivo, could be associated with increased AV accumulation within hypoxic tumor cells, induced by Ced and possibly Quin, in combination with late-stage autophagic inhibition by Quin. These findings provide a rationale for a careful evaluation of a Ced+Quin combination therapy in patients with malignant gliomas.

Citation Format: Merryl Lobo, Peter Kurre, Matthias Schabel, Yancey Gillespie, Randall Woltjer, Martin Pike. Combined efficacy of Cediranib and Quinacrine in glioma is enhanced by hypoxia and is associated with autophagic vacuole accumulation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1679. doi:10.1158/1538-7445.AM2013-1679

Trajectory of white matter hyperintensity burden preceding mild cognitive impairment

OBJECTIVE

To determine the time of acceleration in white matter hyperintensity (WMH) burden, a common indicator of cerebrovascular pathology, in relation to conversion to mild cognitive impairment (MCI) in the elderly.

METHODS

A total of 181 cognitively intact elderly volunteers from the longitudinal, prospective, Oregon Brain Aging Study underwent yearly evaluations, including brain MRI, and cognitive testing. MRIs were analyzed for imaging markers of neurodegeneration: WMH and ventricular CSF (vCSF) volumes. The time before MCI, when the changes in WMH and vCSF burden accelerate, was assessed using a mixed-effects model with a change point for subjects who developed MCI during follow-up.

RESULTS

During a follow-up duration of up to 19.6 years, 134 subjects converted to MCI. Acceleration in %WMH volume increase occurred 10.6 years before MCI onset. On average, the annual rate of change in %WMH increased an additional 3.3% after the change point. Acceleration in %vCSF volume increase occurred 3.7 years before the onset of MCI. Out of 63 subjects who converted to MCI and had autopsy, only 28.5% had Alzheimer disease (AD) as the sole etiology of their dementia, while almost just as many (24%) had both AD and significant ischemic cerebrovascular disease present.

CONCLUSIONS

Acceleration in WMH burden, a common indicator of cerebrovascular disease in the elderly, is a pathologic change that emerges early in the presymptomatic phase leading to MCI. Longitudinal changes in WMH may thus be useful in determining those at risk for cognitive impairment and for planning strategies for introducing disease-modifying therapies prior to dementia onset.

Ecology of the aging human brain

BACKGROUND

Alzheimer disease, cerebral vascular brain injury, and isocortical Lewy body disease (LBD) are the major contributors to dementia in community- and population-based studies.

OBJECTIVE

To estimate the prevalence of clinically silent forms of these diseases in cognitively normal (CN) adults.

DESIGN

Autopsy study.

SETTING

Community- and population based.

PARTICIPANTS

A total of 1672 brain autopsies from the Adult Changes in Thought study, Honolulu-Asia Aging Study, Nun Study, and Oregon Brain Aging Study, of which 424 met the criteria for CN.

MAIN OUTCOME MEASURES

Of these, 336 cases had a comprehensive neuropathologic examination of neuritic plaque density, Braak stage for neurofibrillary tangles, LB distribution, and number of cerebral microinfarcts.

RESULTS

Forty-seven percent of CN cases had moderate or frequent neuritic plaque density; of these, 6% also had Braak stage V or VI for neurofibrillary tangles. Fifteen percent of CN cases had medullary LBD; 8% also had nigral and 4% isocortical LBD. The presence of any cerebral microinfarcts was identified in 33% and of high-level cerebral microinfarcts in 10% of CN individuals. Overall, the burden of lesions in each individual and their comorbidity varied widely within each study but were similar across studies.

CONCLUSIONS

These data show an individually varying complex convergence of subclinical diseases in the brain of older CN adults. Appreciating this ecology should help guide future biomarker and neuroimaging studies and clinical trials that focus on community- and population-based cohorts.

Dysregulated phosphorylation of Ca(2+) /calmodulin-dependent protein kinase II-α in the hippocampus of subjects with mild cognitive impairment and Alzheimer's disease

Alzheimer's disease (AD) is a progressive, neurodegenerative disorder and the most prevalent senile dementia. The early symptom of memory dysfunction involves synaptic loss, thought to be mediated by soluble amyloid-beta (Aβ) oligomers. These aggregate species target excitatory synapses and their levels correlate with disease severity. Studies in cell culture and rodents have shown that oligomers increase intracellular calcium (Ca(2+)), impairing synaptic plasticity. Yet, the molecular mechanism mediating Aβ oligomers' toxicity in the aged brain remains unclear. Here, we apply quantitative immunofluorescence in human brain tissue from clinically diagnosed mild cognitive impaired (MCI) and AD patients to investigate the distribution of phosphorylated (active) Ca(2+) /calmodulin-dependent protein kinase-α (p(Thr286)CaMKII), a critical enzyme for activity-dependent synaptic remodeling associated with cognitive function. We show that p(Thr286)CaMKII immunoreactivity is redistributed from dendritic arborizations to neural perikarya of both MCI and AD hippocampi. This finding correlates with cognitive assessment scores, suggesting that it may be a molecular read-out of the functional deficits in early AD. Treatment with oligomeric Aβ replicated the observed phenotype in mice and resulted in a loss of p(Thr286)CaMKII from synaptic spines of primary hippocampal neurons. Both outcomes were prevented by inhibiting the phosphatase calcineurin (CaN). Collectively, our results support a model in which the synaptotoxicity of Aβ oligomers in human brain involves the CaN-dependent subcellular redistribution of p(Thr286)CaMKII. Therapies designed to normalize the homeostatic imbalance of neuronal phosphatases and downstream dephosphorylation of synaptic p(Thr286)CaMKII should be considered to prevent and treat early AD.

The spectrum of mutations in progranulin: a collaborative study screening 545 cases of neurodegeneration

BACKGROUND

Mutation in the progranulin gene (GRN) can cause frontotemporal dementia (FTD). However, it is unclear whether some rare FTD-related GRN variants are pathogenic and whether neurodegenerative disorders other than FTD can also be caused by GRN mutations.

OBJECTIVES

To delineate the range of clinical presentations associated with GRN mutations and to define pathogenic candidacy of rare GRN variants.

DESIGN

Case-control study.

SETTING

Clinical and neuropathology dementia research studies at 8 academic centers.

PARTICIPANTS

Four hundred thirty-four patients with FTD, including primary progressive aphasia, semantic dementia, FTD/amyotrophic lateral sclerosis (ALS), FTD/motor neuron disease, corticobasal syndrome/corticobasal degeneration, progressive supranuclear palsy, Pick disease, dementia lacking distinctive histopathology, and pathologically confirmed cases of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U); and 111 non-FTD cases (controls) in which TDP-43 deposits were a prominent neuropathological feature, including subjects with ALS, Guam ALS and/or parkinsonism dementia complex, Guam dementia, Alzheimer disease, multiple system atrophy, and argyrophilic grain disease.

MAIN OUTCOME MEASURES

Variants detected on sequencing of all 13 GRN exons and at least 80 base pairs of flanking introns, and their pathogenic candidacy determined by in silico and ex vivo splicing assays.

RESULTS

We identified 58 genetic variants that included 26 previously unknown changes. Twenty-four variants appeared to be pathogenic, including 8 novel mutations. The frequency of GRN mutations was 6.9% (30 of 434) of all FTD-spectrum cases, 21.4% (9 of 42) of cases with a pathological diagnosis of FTLD-U, 16.0% (28 of 175) of FTD-spectrum cases with a family history of a similar neurodegenerative disease, and 56.2% (9 of 16) of cases of FTLD-U with a family history.

CONCLUSIONS

Pathogenic mutations were found only in FTD-spectrum cases and not in other related neurodegenerative diseases. Haploinsufficiency of GRN is the predominant mechanism leading to FTD.

Different patterns of cerebral injury in dementia with or without diabetes

BACKGROUND

Diabetes mellitus (DM) increases the risk of dementia in the elderly. However, its underlying mechanisms, its connection with Alzheimer disease and vascular cognitive impairment, and effects of therapy remain unclear.

OBJECTIVE

To test the hypothesis that DM promotes specific neuropathologic processes that contribute to dementia and that these processes may be suppressed by antidiabetic therapy.

DESIGN

A comprehensive neuropathologic assessment of all cases from a community-based study of incident dementia (Adult Changes in Thought Study) that underwent autopsies (n = 259) and had information on DM status (n = 196). Biochemical analysis was conducted on a subset of these cases with rapidly frozen brain tissue (n = 57).

PARTICIPANTS

Autopsy cases were divided into 4 groups: no DM/no dementia (DM-/dementia-), DM/no dementia (DM+/dementia-), no DM/dementia (DM-/dementia+), and DM/dementia (DM+/dementia+). Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) diagnosis of dementia was assigned through a consensus of experts following biennial cognitive and physical evaluations. Diabetes was diagnosed based on information obtained from participants' extensive medical records.

RESULTS

In cases without dementia (n = 125), neuropathologic and biochemical end points did not differ significantly by DM status. However, we observed 2 patterns of injury in patients with dementia (n = 71) by their DM status. Individuals without DM but with dementia (DM-/dementia+) had a greater amyloid-beta peptide load and increased levels of F(2)-isoprostanes in the cerebral cortex, while DM+/dementia+ patients had more microvascular infarcts and an increased cortical IL-6 (interleukin 6) concentration. The number of microvascular infarcts was greater in deep cerebral structures in patients with dementia whose diabetes was treated, whereas amyloid plaque load tended to be greater for untreated diabetic patients with dementia.

CONCLUSIONS

These novel characterizations of 2 different patterns of cerebral injury in patients with dementia depending on DM status may have etiologic and therapeutic implications. Published online January 12, 2009 (doi:10.1001/archneurol.2008.579).

Empiric refinement of the pathologic assessment of Lewy-related pathology in the dementia patient

Lewy-related pathology (LRP) is a common pathologic finding at autopsy in dementia patients. Recently criteria for categorizing types of LRP in dementia patients were published, though these criteria have yet to be systematically applied to large dementia samples. We examined a large (n = 208) referral-based autopsy sample for LRP, and applied the published criteria for LRP categorization to these cases. We found almost half (49%) of LRP positive cases from this sample were not classifiable. However, modifying the published criteria by reducing the number of regions requiring examination, allowing more variability in LRP severity scores within specific brain regions, and adding an amygdala predominant category permitted classification of 97% of LRP positive cases from the referral-based sample. Application of the modified criteria to an unrelated community-based autopsy sample (n = 226) allowed classification of 96% of LRP positive cases. Modest modifications in the published criteria permit a significantly greater number of dementia cases with LRP to be classified. In addition, this modification allows for more limited sampling of brain regions for classification of LRP. We propose that these modified criteria for the categorization of LRP be utilized in patients with a history of dementia.