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  1. Article ; Online: Microglial Progranulin

    Anarmaa Mendsaikhan / Ikuo Tooyama / Douglas G. Walker

    Cells, Vol 8, Iss 3, p

    Involvement in Alzheimer’s Disease and Neurodegenerative Diseases

    2019  Volume 230

    Abstract: Neurodegenerative diseases such as Alzheimer’s disease have proven resistant to new treatments. The complexity of neurodegenerative disease mechanisms can be highlighted by accumulating evidence for a role for a growth factor, progranulin (PGRN). PGRN is ...

    Abstract Neurodegenerative diseases such as Alzheimer’s disease have proven resistant to new treatments. The complexity of neurodegenerative disease mechanisms can be highlighted by accumulating evidence for a role for a growth factor, progranulin (PGRN). PGRN is a glycoprotein encoded by the GRN/Grn gene with multiple cellular functions, including neurotrophic, anti-inflammatory and lysosome regulatory properties. Mutations in the GRN gene can lead to frontotemporal lobar degeneration (FTLD), a cause of dementia, and neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disease. Both diseases are associated with loss of PGRN function resulting, amongst other features, in enhanced microglial neuroinflammation and lysosomal dysfunction. PGRN has also been implicated in Alzheimer’s disease (AD). Unlike FTLD, increased expression of PGRN occurs in brains of human AD cases and AD model mice, particularly in activated microglia. How microglial PGRN might be involved in AD and other neurodegenerative diseases will be discussed. A unifying feature of PGRN in diseases might be its modulation of lysosomal function in neurons and microglia. Many experimental models have focused on consequences of PGRN gene deletion: however, possible outcomes of increasing PGRN on microglial inflammation and neurodegeneration will be discussed. We will also suggest directions for future studies on PGRN and microglia in relation to neurodegenerative diseases.
    Keywords neuroinflammation ; growth factor ; anti-inflammatory ; mutation ; amyloid ; neurodegeneration ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2019-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Alzheimer’s Disease Research Using Human Microglia

    Lih-Fen Lue / Thomas G. Beach / Douglas G. Walker

    Cells, Vol 8, Iss 8, p

    2019  Volume 838

    Abstract: Experimental studies of neuroinflammation in Alzheimer’s disease (AD) have mostly investigated microglia, the brain-resident macrophages. This review focused on human microglia obtained at rapid autopsies. Studies employing methods to isolate and culture ...

    Abstract Experimental studies of neuroinflammation in Alzheimer’s disease (AD) have mostly investigated microglia, the brain-resident macrophages. This review focused on human microglia obtained at rapid autopsies. Studies employing methods to isolate and culture human brain microglia in high purity for experimental studies were discussed. These methods were employed to isolate human microglia for investigation of a number of features of neuroinflammation, including activation phenotypes, neurotoxicity, responses to abnormal aggregated proteins such as amyloid beta, phagocytosis, and the effects of aging and disease on microglia cellular properties. In recent years, interest in human microglia and neuroinflammation has been renewed due to the identification of inflammation-related AD genetic risk factors, in particular the triggering receptor expressed on myeloid cells (TREM)-2. Because of the difficulties in developing effective treatments for AD, there has been a general need for greater understanding of the functions of microglia in normal and AD brains. While most experimental studies on neuroinflammation have employed rodent microglia, this review considered the role of human microglia in experimental studies. This review focused on the development of in vitro methodology for the culture of postmortem human microglia and the key findings obtained from experimental studies with these cells.
    Keywords neuroinflammation ; microglia ; cell culture ; brain ; amyloid ; neurodegeneration ; autopsy ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2019-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Effects of FTMT Expression by Retinal Pigment Epithelial Cells on Features of Angiogenesis

    Undral Buyandelger / Douglas G. Walker / Daijiro Yanagisawa / Toshifumi Morimura / Ikuo Tooyama

    International Journal of Molecular Sciences, Vol 21, Iss 3635, p

    2020  Volume 3635

    Abstract: Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, ...

    Abstract Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, can result from pathological angiogenesis. As a mutation in the mitochondrial ferritin (FTMT) gene has been associated with AMD, its possible role in modulating angiogenic factors and angiogenesis was investigated. FTMT is an iron-sequestering protein primarily expressed in metabolically active cells and tissues with high oxygen demand, including retina. In this study, we utilized the human retinal pigment epithelial cell line ARPE-19, both as undifferentiated and differentiated cells. The effects of proinflammatory cytokines, FTMT knockdown, and transient and stable overexpression of FTMT were investigated on expression of pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial-derived factor (PEDF). Proinflammatory cytokines induced FTMT and VEGF expression, while NF-κB inhibition significantly reduced FTMT expression. VEGF protein and mRNA expression were significantly increased in FTMT-silenced ARPE-19 cells. Using an in vitro angiogenesis assay with endothelial cells, we showed that conditioned media from FTMT-overexpressing cells had significant antiangiogenic effects. Collectively, our findings indicate that increased levels of FTMT inhibit angiogenesis, possibly by reducing levels of VEGF and increasing PEDF expression. The cellular models developed can be used to investigate if increased FTMT may be protective in angiogenic diseases, such as AMD.
    Keywords mitochondrial ferritin ; vascular endothelial growth factor ; angiogenesis ; retinal pigment epithelium ; age-related macular degeneration ; differentiation ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 610
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Microglial Phenotyping in Neurodegenerative Disease Brains

    Douglas G. Walker / Lih-Fen Lue / Thomas G. Beach / Ikuo Tooyama

    Cells, Vol 8, Iss 7, p

    Identification of Reactive Microglia with an Antibody to Variant of CD105/Endoglin

    2019  Volume 766

    Abstract: Inflammation is considered a key pathological process in neurodegenerative diseases, including Alzheimer’s disease (AD) and Parkinson’s disease (PD), but there are still mechanisms not understood. In the brain, most microglia are performing essential ... ...

    Abstract Inflammation is considered a key pathological process in neurodegenerative diseases, including Alzheimer’s disease (AD) and Parkinson’s disease (PD), but there are still mechanisms not understood. In the brain, most microglia are performing essential homeostatic functions, but can also respond to pathogenic stimuli by producing harmful pro-inflammatory cytokines or free radicals. Distinguishing between damaging and homeostatic microglia in human diseased brain tissues is a challenge. This report describes findings using a monoclonal antibody to CD105/Endoglin (R&D Systems MAB1097) that identifies subtypes of activated microglia. CD105/Endoglin is a co-receptor for transforming growth factor beta (TGFβ) receptor that antagonizes TGFβ signaling. CD105/Endoglin is a marker for vascular endothelial cells, but was originally identified as a marker for activated macrophages. This antibody did not identify endothelial cells in brain sections, only microglia-like cells. In this study, we examined with this antibody tissue section from middle temporal gyrus derived from human brains from normal control subjects with low-plaque pathology, high-plaque pathology, and AD cases, and also substantia nigra samples from control and PD cases, in conjunction with antibodies to markers of pathology and microglia. In low-plaque pathology cases, CD105-positive microglia were mostly absent, but noticeably increased with increasing pathology. CD105-positive cells strongly colocalized with amyloid-beta plaques, but not phosphorylated tau positive tangles. In substantia nigra, strong microglial CD105 staining was observed in microglia associated with degenerating dopaminergic neurons and neuromelanin. In PD cases with few surviving dopaminergic neurons, this staining had decreased. By Western blot, this antibody identified polypeptide bands of 70 kDa in brain samples, and samples from microglia, macrophages, and brain endothelial cells. In comparison with other tested CD105 antibodies, this antibody did not recognize the glycosylated ...
    Keywords neuroinflammation ; neuropathology ; transforming growth factor ; activation ; microglia ; immunohistochemistry ; human ; Biology (General) ; QH301-705.5
    Subject code 616
    Language English
    Publishing date 2019-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Patterns of Expression of Purinergic Receptor P2RY12, a Putative Marker for Non-Activated Microglia, in Aged and Alzheimer’s Disease Brains

    Douglas G. Walker / Tiffany M. Tang / Anarmaa Mendsaikhan / Ikuo Tooyama / Geidy E. Serrano / Lucia I. Sue / Thomas G. Beach / Lih-Fen Lue

    International Journal of Molecular Sciences, Vol 21, Iss 2, p

    2020  Volume 678

    Abstract: Neuroinflammation is considered a key pathological process in neurodegenerative diseases of aging, including Alzheimer’s disease (AD). Many studies have defined phenotypes of reactive microglia, the brain-resident macrophages, with different antigenic ... ...

    Abstract Neuroinflammation is considered a key pathological process in neurodegenerative diseases of aging, including Alzheimer’s disease (AD). Many studies have defined phenotypes of reactive microglia, the brain-resident macrophages, with different antigenic markers to identify those potentially causing inflammatory damage. We took an alternative approach with the goal of characterizing the distribution of purinergic receptor P2RY12-positive microglia, a marker previously defined as identifying homeostatic or non-activated microglia. We examined the expression of P2RY12 by dual-color light and fluorescence immunohistochemistry using sections of middle temporal gyrus from AD, high plaque and low plaque non-demented cases in relation to amyloid beta (Aβ) plaques and phosphorylated tau, markers of pathology, and HLA-DR, IBA-1, CD68, and progranulin, microglial phenotype markers. In low plaque cases, P2RY12-positive microglia mostly had non-activated morphologies, while the morphologies of P2RY12-positive microglia in AD brains were highly variable, suggesting its expression could encompass a wider range of phenotypes than originally hypothesized. P2RY12 expression by microglia differed depending on the types of plaques or tangles they were associated with. Areas of inflammation characterized by lack of P2RY12-positive microglia around mature plaques could be observed, but many diffuse plaques showed colocalization with P2RY12-positive microglia. Based on these results, P2RY12 expression by microglia should not be considered solely a marker of resting microglia as P2RY12 immunoreactivity was identifying microglia positive for CD68, progranulin and to a limited extent HLA-DR, markers of activation.
    Keywords activation phenotypes ; microglia ; neuroinflammation ; immunohistochemistry ; temporal cortex ; alzheimer’s disease ; amyloid ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 610
    Language English
    Publishing date 2020-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Biochemical assessment of precuneus and posterior cingulate gyrus in the context of brain aging and Alzheimer's disease.

    Chera L Maarouf / Tyler A Kokjohn / Douglas G Walker / Charisse M Whiteside / Walter M Kalback / Alexis Whetzel / Lucia I Sue / Geidy Serrano / Sandra A Jacobson / Marwan N Sabbagh / Eric M Reiman / Thomas G Beach / Alex E Roher

    PLoS ONE, Vol 9, Iss 8, p e

    2014  Volume 105784

    Abstract: Defining the biochemical alterations that occur in the brain during "normal" aging is an important part of understanding the pathophysiology of neurodegenerative diseases and of distinguishing pathological conditions from aging-associated changes. Three ... ...

    Abstract Defining the biochemical alterations that occur in the brain during "normal" aging is an important part of understanding the pathophysiology of neurodegenerative diseases and of distinguishing pathological conditions from aging-associated changes. Three groups were selected based on age and on having no evidence of neurological or significant neurodegenerative disease: 1) young adult individuals, average age 26 years (n = 9); 2) middle-aged subjects, average age 59 years (n = 5); 3) oldest-old individuals, average age 93 years (n = 6). Using ELISA and Western blotting methods, we quantified and compared the levels of several key molecules associated with neurodegenerative disease in the precuneus and posterior cingulate gyrus, two brain regions known to exhibit early imaging alterations during the course of Alzheimer's disease. Our experiments revealed that the bioindicators of emerging brain pathology remained steady or decreased with advancing age. One exception was S100B, which significantly increased with age. Along the process of aging, neurofibrillary tangle deposition increased, even in the absence of amyloid deposition, suggesting the presence of amyloid plaques is not obligatory for their development and that limited tangle density is a part of normal aging. Our study complements a previous assessment of neuropathology in oldest-old subjects, and within the limitations of the small number of individuals involved in the present investigation, it adds valuable information to the molecular and structural heterogeneity observed along the course of aging and dementia. This work underscores the need to examine through direct observation how the processes of amyloid deposition unfold or change prior to the earliest phases of dementia emergence.
    Keywords Medicine ; R ; Science ; Q
    Subject code 616
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Quantitative Appraisal of Ventricular Cerebrospinal Fluid Biomarkers in Neuropathologically Diagnosed Parkinson's Disease Cases Lacking Alzheimer's Disease Pathology

    Chera L. Maarouf / Thomas G. Beach / Charles H. Adler / Michael Malek-Ahmadi / Tyler A. Kokjohn / Brittany N. Dugger / Douglas G. Walker / Holly A. Shill / Sandra A. Jacobson / Marwan N. Sabbagh / Alex E. Roher / Arizona Parkinson’s Disease Consortium

    Biomarker Insights, Vol 2013, Iss 8, Pp 19-

    2013  Volume 28

    Keywords Medicine (General) ; R5-920
    Language English
    Publishing date 2013-03-01T00:00:00Z
    Publisher SAGE Publishing
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Quantitative Appraisal of Ventricular Cerebrospinal Fluid Biomarkers in Neuropathologically Diagnosed Parkinson's Disease Cases Lacking Alzheimer's Disease Pathology

    Chera L. Maarouf / Thomas G. Beach / Charles H. Adler / Michael Malek-Ahmadi / Tyler A. Kokjohn / Brittany N. Dugger / Douglas G. Walker / Holly A. Shill / Sandra A. Jacobson / Marwan N. Sabbagh / Alex E. Roher

    Biomarker Insights, Vol

    2013  Volume 8

    Abstract: Identifying biomarkers that distinguish Parkinson's disease (PD) from normal control (NC) individuals has the potential to increase diagnostic sensitivity for the detection of early-stage PD. A previous proteomic study identified potential biomarkers in ... ...

    Abstract Identifying biomarkers that distinguish Parkinson's disease (PD) from normal control (NC) individuals has the potential to increase diagnostic sensitivity for the detection of early-stage PD. A previous proteomic study identified potential biomarkers in postmortem ventricular cerebrospinal fluid (V-CSF) from neuropathologically diagnosed PD subjects lacking Alzheimer's disease (AD) neuropathology. In the present study, we assessed these biomarkers as well as p-tau 181 , Aβ42, and S100B by ELISA in PD (n = 43) and NC (n = 49) cases. The p-tau 181 /Aβ42 ratio and ApoA-1 showed statistically significant differences between groups. Multiple regression analysis demonstrated that p-tau 181 /Aβ42 had a significant odds ratio: OR = 1.42 (95% confidence interval [CI], 1.12–1.84), P = 0.006. Among the molecules investigated, intriguing correlations were observed that require further investigation. Our results suggest coexistent AD CSF biomarkers within the PD group notwithstanding that it was selected to minimize AD neuropathological lesions.
    Keywords Medicine (General) ; R5-920
    Language English
    Publishing date 2013-01-01T00:00:00Z
    Publisher SAGE Publishing
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Faster cognitive decline in dementia due to Alzheimer disease with clinically undiagnosed Lewy body disease.

    Michael Malek-Ahmadi / Thomas G Beach / Edward Zamrini / Charles H Adler / Marwan N Sabbagh / Holly A Shill / Sandra A Jacobson / Christine M Belden / Richard J Caselli / Brian K Woodruff / Steven Z Rapscak / Geoffrey L Ahern / Jiong Shi / John N Caviness / Erika Driver-Dunckley / Shyamal H Mehta / David R Shprecher / Bryan M Spann / Pierre Tariot /
    Kathryn J Davis / Kathy E Long / Lisa R Nicholson / Anthony Intorcia / Michael J Glass / Jessica E Walker / Michael Callan / Jasmine Curry / Brett Cutler / Javon Oliver / Richard Arce / Douglas G Walker / Lih-Fen Lue / Geidy E Serrano / Lucia I Sue / Kewei Chen / Eric M Reiman

    PLoS ONE, Vol 14, Iss 6, p e

    2019  Volume 0217566

    Abstract: Background Neuropathology has demonstrated a high rate of comorbid pathology in dementia due to Alzheimer's disease (ADD). The most common major comorbidity is Lewy body disease (LBD), either as dementia with Lewy bodies (AD-DLB) or Alzheimer's disease ... ...

    Abstract Background Neuropathology has demonstrated a high rate of comorbid pathology in dementia due to Alzheimer's disease (ADD). The most common major comorbidity is Lewy body disease (LBD), either as dementia with Lewy bodies (AD-DLB) or Alzheimer's disease with Lewy bodies (AD-LB), the latter representing subjects with ADD and LBD not meeting neuropathological distribution and density thresholds for DLB. Although it has been established that ADD subjects with undifferentiated LBD have a more rapid cognitive decline than those with ADD alone, it is still unknown whether AD-LB subjects, who represent the majority of LBD and approximately one-third of all those with ADD, have a different clinical course. Methods Subjects with dementia included those with "pure" ADD (n = 137), AD-DLB (n = 64) and AD-LB (n = 114), all with two or more complete Mini Mental State Examinations (MMSE) and a full neuropathological examination. Results Linear mixed models assessing MMSE change showed that the AD-LB group had significantly greater decline compared to the ADD group (β = -0.69, 95% CI: -1.05, -0.33, p<0.001) while the AD-DLB group did not (β = -0.30, 95% CI: -0.73, 0.14, p = 0.18). Of those with AD-DLB and AD-LB, only 66% and 2.1%, respectively, had been diagnosed with LBD at any point during their clinical course. Compared with clinically-diagnosed AD-DLB subjects, those that were clinically undetected had significantly lower prevalences of parkinsonism (p = 0.046), visual hallucinations (p = 0.0008) and dream enactment behavior (0.013). Conclusions The probable cause of LBD clinical detection failure is the lack of a sufficient set of characteristic core clinical features. Core DLB clinical features were not more common in AD-LB as compared to ADD. Clinical identification of ADD with LBD would allow stratified analyses of ADD clinical trials, potentially improving the probability of trial success.
    Keywords Medicine ; R ; Science ; Q
    Subject code 610
    Language English
    Publishing date 2019-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Alzheimer's disease and non-demented high pathology control nonagenarians

    Chera L Maarouf / Ian D Daugs / Tyler A Kokjohn / Douglas G Walker / Jesse M Hunter / Jane C Kruchowsky / Randy Woltjer / Jeffrey Kaye / Eduardo M Castaño / Marwan N Sabbagh / Thomas G Beach / Alex E Roher

    PLoS ONE, Vol 6, Iss 11, p e

    comparing and contrasting the biochemistry of cognitively successful aging.

    2011  Volume 27291

    Abstract: The amyloid cascade hypothesis provides an economical mechanistic explanation for Alzheimer's disease (AD) dementia and correlated neuropathology. However, some nonagenarian individuals (high pathology controls, HPC) remain cognitively intact while ... ...

    Abstract The amyloid cascade hypothesis provides an economical mechanistic explanation for Alzheimer's disease (AD) dementia and correlated neuropathology. However, some nonagenarian individuals (high pathology controls, HPC) remain cognitively intact while enduring high amyloid plaque loads for decades. If amyloid accumulation is the prime instigator of neurotoxicity and dementia, specific protective mechanisms must enable these HPC to evade cognitive decline. We evaluated the neuropathological and biochemical differences existing between non-demented (ND)-HPC and an age-matched cohort with AD dementia. The ND-HPC selected for our study were clinically assessed as ND and possessed high amyloid plaque burdens. ELISA and Western blot analyses were used to quantify a group of proteins related to APP/Aβ/tau metabolism and other neurotrophic and inflammation-related molecules that have been found to be altered in neurodegenerative disorders and are pivotal to brain homeostasis and mental health. The molecules assumed to be critical in AD dementia, such as soluble or insoluble Aβ40, Aβ42 and tau were quantified by ELISA. Interestingly, only Aβ42 demonstrated a significant increase in ND-HPC when compared to the AD group. The vascular amyloid load which was not used in the selection of cases, was on the average almost 2-fold greater in AD than the ND-HPC, suggesting that a higher degree of microvascular dysfunction and perfusion compromise was present in the demented cohort. Neurofibrillary tangles were less frequent in the frontal cortices of ND-HPC. Biochemical findings included elevated vascular endothelial growth factor, apolipoprotein E and the neuroprotective factor S100B in ND-HPC, while anti-angiogenic pigment epithelium derived factor levels were lower. The lack of clear Aβ-related pathological/biochemical demarcation between AD and ND-HPC suggests that in addition to amyloid plaques other factors, such as neurofibrillary tangle density and vascular integrity, must play important roles in cognitive failure.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2011-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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