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Niedowicz DM, Gollihue JL, Weekman EM, Phe P, Wilcock DM, Norris CM, Nelson PT. Using digital pathology to analyze the murine cerebrovasculature. J Cereb Blood Flow Metab 2024; 44:595-610. [PMID: 37988134 PMCID: PMC10981399 DOI: 10.1177/0271678x231216142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/22/2023]
Abstract
Research on the cerebrovasculature may provide insights into brain health and disease. Immunohistochemical staining is one way to visualize blood vessels, and digital pathology has the potential to revolutionize the measurement of blood vessel parameters. These tools provide opportunities for translational mouse model research. However, mouse brain tissue presents a formidable set of technical challenges, including potentially high background staining and cross-reactivity of endogenous IgG. Formalin-fixed paraffin-embedded (FFPE) and fixed frozen sections, both of which are widely used, may require different methods. In this study, we optimized blood vessel staining in mouse brain tissue, testing both FFPE and frozen fixed sections. A panel of immunohistochemical blood vessel markers were tested (including CD31, CD34, collagen IV, DP71, and VWF), to evaluate their suitability for digital pathological analysis. Collagen IV provided the best immunostaining results in both FFPE and frozen fixed murine brain sections, with highly-specific staining of large and small blood vessels and low background staining. Subsequent analysis of collagen IV-stained sections showed region and sex-specific differences in vessel density and vessel wall thickness. We conclude that digital pathology provides a useful tool for relatively unbiased analysis of the murine cerebrovasculature, provided proper protein markers are used.
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Affiliation(s)
- Dana M Niedowicz
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Jenna L Gollihue
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Erica M Weekman
- Stark Neurosciences Research Institute, Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Panhavuth Phe
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Donna M Wilcock
- Stark Neurosciences Research Institute, Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Christopher M Norris
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, USA
- Department of Pharmacology, University of Kentucky, Lexington, KY, USA
| | - Peter T Nelson
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, USA
- Department of Pathology, University of Kentucky, Lexington, KY, USA
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Foley KE, Winder Z, Sudduth TL, Martin BJ, Nelson PT, Jicha GA, Harp JP, Weekman EM, Wilcock DM. Alzheimer's disease and inflammatory biomarkers positively correlate in plasma in the UK-ADRC cohort. Alzheimers Dement 2024; 20:1374-1386. [PMID: 38011580 PMCID: PMC10917006 DOI: 10.1002/alz.13485] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 08/17/2023] [Accepted: 08/20/2023] [Indexed: 11/29/2023]
Abstract
INTRODUCTION Protein-based plasma assays provide hope for improving accessibility and specificity of molecular diagnostics to diagnose dementia. METHODS Plasma was obtained from participants (N = 837) in our community-based University of Kentucky Alzheimer's Disease Research Center cohort. We evaluated six Alzheimer's disease (AD)- and neurodegeneration-related (Aβ40, Aβ42, Aβ42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNF𝛼, IL6, IL8, IL10, and GFAP) using the SIMOA-based protein assay platform. Statistics were performed to assess correlations. RESULTS Our large cohort reflects previous plasma biomarker findings. Relationships between biomarkers to understand AD-inflammatory biomarker correlations showed significant associations between AD and inflammatory biomarkers suggesting peripheral inflammatory interactions with increasing AD pathology. Biomarker associations parsed out by clinical diagnosis (normal, MCI, and dementia) reveal changes in strength of the correlations across the cognitive continuum. DISCUSSION Unique AD-inflammatory biomarker correlations in a community-based cohort reveal a new avenue for utilizing plasma-based biomarkers in the assessment of AD and related dementias. HIGHLIGHTS Large community cohorts studying sex, age, and APOE genotype effects on biomarkers are few. It is unknown how biomarker-biomarker associations vary through aging and dementia. Six AD (Aβ40, Aβ42, Aβ42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNFα, IL6, IL8, IL10, and GFAP) were used to examine associations between biomarkers. Plasma biomarkers suggesting increasing cerebral AD pathology corresponded to increases in peripheral inflammatory markers, both pro-inflammatory and anti-inflammatory. Strength of correlations, between pairs of classic AD and inflammatory plasma biomarker, changes throughout cognitive progression to dementia.
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Affiliation(s)
- Kate E. Foley
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
| | - Zachary Winder
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
- College of MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Tiffany L. Sudduth
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
| | - Barbara J. Martin
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Peter T. Nelson
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Pathology and Laboratory MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Gregory A. Jicha
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Neurology, College of Public HealthUniversity of KentuckyLexingtonKentuckyUSA
| | - Jordan P. Harp
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Neurology, College of Public HealthUniversity of KentuckyLexingtonKentuckyUSA
| | - Erica M. Weekman
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
| | - Donna M. Wilcock
- Sanders Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
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Foley KE, Weekman EM, Wilcock DM. Mechanisms of ARIA: is it time to focus on the unique immune environment of the neurovascular unit? Mol Neurodegener 2023; 18:76. [PMID: 37858154 PMCID: PMC10588106 DOI: 10.1186/s13024-023-00667-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023] Open
Affiliation(s)
- Kate E Foley
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th St, Indianapolis, IN, 46202, USA
- Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Erica M Weekman
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th St, Indianapolis, IN, 46202, USA
- Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Donna M Wilcock
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th St, Indianapolis, IN, 46202, USA.
- Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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Weekman EM, Johnson SN, Rogers CB, Sudduth TL, Xie K, Qiao Q, Fardo DW, Bottiglieri T, Wilcock DM. Atorvastatin rescues hyperhomocysteinemia-induced cognitive deficits and neuroinflammatory gene changes. J Neuroinflammation 2023; 20:199. [PMID: 37658433 PMCID: PMC10474691 DOI: 10.1186/s12974-023-02883-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 08/28/2023] [Indexed: 09/03/2023] Open
Abstract
BACKGROUND Epidemiological data suggests statins could reduce the risk of dementia, and more specifically, Alzheimer's disease (AD). Pre-clinical data suggests statins reduce the risk of dementia through their pleiotropic effects rather than their cholesterol lowering effects. While AD is a leading cause of dementia, it is frequently found co-morbidly with cerebral small vessel disease and other vascular contributions to cognitive impairment and dementia (VCID), which are another leading cause of dementia. In this study, we determined if atorvastatin ameliorated hyperhomocysteinemia (HHcy)-induced VCID. METHODS Wild-type (C57Bl6/J) mice were placed on a diet to induce HHcy or a control diet each with or without atorvastatin for 14 weeks. Mice underwent novel object recognition testing before tissue collection. Plasma total cholesterol and total homocysteine as well as related metabolites were measured. Using qPCR and NanoString technology, we profiled glial cell-associated gene expression changes. Finally, microglial morphology, astrocyte end feet, and microhemorrhages were analyzed using histological methods. RESULTS Atorvastatin treatment of HHcy in mice led to no changes in total cholesterol but decreases in total homocysteine in plasma. While HHcy decreased expression of many glial genes, atorvastatin rescued these gene changes, which mostly occurred in oligodendrocytes and microglia. Microglia in HHcy mice with atorvastatin were trending towards fewer processes compared to control with atorvastatin, but there were no atorvastatin effects on astrocyte end feet. While atorvastatin treatment was trending towards increasing the area of microhemorrhages in HHcy mice in the frontal cortex, it only slightly (non-significantly) reduced the number of microhemorrhages. Finally, atorvastatin treatment in HHcy mice led to improved cognition on the novel object recognition task. CONCLUSIONS These data suggest that atorvastatin rescued cognitive changes induced by HHcy most likely through lowering plasma total homocysteine and rescuing gene expression changes rather than impacts on vascular integrity or microglial changes.
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Affiliation(s)
- Erica M Weekman
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA.
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Sherika N Johnson
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Colin B Rogers
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Tiffany L Sudduth
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Kevin Xie
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Qi Qiao
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - David W Fardo
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Teodoro Bottiglieri
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott and White Research Institute, Dallas, TX, 75204, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
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Kloske CM, Gearon MD, Weekman EM, Rogers C, Patel E, Bachstetter A, Nelson PT, Wilcock DM. Association between APOE genotype and microglial cell morphology. J Neuropathol Exp Neurol 2023; 82:620-630. [PMID: 37087107 PMCID: PMC10280358 DOI: 10.1093/jnen/nlad031] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023] Open
Abstract
APOE is the largest genetic risk factor for late-onset Alzheimer disease (AD) with E4 conferring an increased risk for AD compared to E3. The ApoE protein can impact diverse pathways in the brain including neuroinflammation but the precise impact of ApoE isoforms on inflammation remains unknown. As microglia are a primary source of neuroinflammation, this study determined whether ApoE isoforms have an impact on microglial morphology and activation using immunohistochemistry and digital analyses. Analysis of ionized calcium-binding adaptor molecule 1 (Iba1) immunoreactivity indicated greater microglial activation in both the hippocampus and superior and middle temporal gyrus (SMTG) in dementia participants versus non-demented controls. Further, only an increase in activation was seen in E3-Dementia participants in the entire SMTG, whereas in the grey matter of the SMTG, only a diagnosis of dementia impacted activation. Specific microglial morphologies showed a reduction in ramified microglia in the dementia group. For rod microglia, a reduction was seen in E4-Control patients in the hippocampus whereas in the SMTG an increase was seen in E4-Dementia patients. These findings suggest an association between ApoE isoforms and microglial morphologies and highlight the importance of considering ApoE isoforms in studies of AD pathology.
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Affiliation(s)
- Courtney M Kloske
- Department of Physiology, College of Medicine, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Mary D Gearon
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Erica M Weekman
- Department of Physiology, College of Medicine, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Colin Rogers
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Ela Patel
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Adam Bachstetter
- Department of Neuroscience, College of Medicine, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Peter T Nelson
- Department of Pathology and Laboratory Medicine, College of Medicine, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Donna M Wilcock
- Department of Physiology, College of Medicine, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
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MacPherson KP, Eidson LN, Houser MC, Weiss BE, Gollihue JL, Herrick MK, de Sousa Rodrigues ME, Sniffen L, Weekman EM, Hamilton AM, Kelly SD, Oliver DL, Yang Y, Chang J, Sampson TR, Norris CM, Tansey MG. Soluble TNF mediates amyloid-independent, diet-induced alterations to immune and neuronal functions in an Alzheimer's disease mouse model. Front Cell Neurosci 2023; 17:895017. [PMID: 37006470 PMCID: PMC10052573 DOI: 10.3389/fncel.2023.895017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 01/20/2023] [Indexed: 03/17/2023] Open
Abstract
Introduction: Increasing evidence indicates that neurodegenerative diseases, including Alzheimer's disease (AD), are a product of gene-by-environment interplay. The immune system is a major contributor mediating these interactions. Signaling between peripheral immune cells and those within the microvasculature and meninges of the central nervous system (CNS), at the blood-brain barrier, and in the gut likely plays an important role in AD. The cytokine tumor necrosis factor (TNF) is elevated in AD patients, regulates brain and gut barrier permeability, and is produced by central and peripheral immune cells. Our group previously reported that soluble TNF (sTNF) modulates cytokine and chemokine cascades that regulate peripheral immune cell traffic to the brain in young 5xFAD female mice, and in separate studies that a diet high in fat and sugar (HFHS) dysregulates signaling pathways that trigger sTNF-dependent immune and metabolic responses that can result in metabolic syndrome, which is a risk factor for AD. We hypothesized that sTNF is a key mediator of peripheral immune cell contributions to gene-by-environment interactions to AD-like pathology, metabolic dysfunction, and diet-induced gut dysbiosis. Methods: Female 5xFAD mice were subjected to HFHS diet for 2 months and then given XPro1595 to inhibit sTNF for the last month or saline vehicle. We quantified immune cell profiles by multi-color flow cytometry on cells isolated from brain and blood; metabolic, immune, and inflammatory mRNA and protein marker biochemical and immunhistological analyses, gut microbiome, and electrophysiology in brain slices were also performed. Results: Here, we show that selective inhibition of sTNF signaling via the biologic XPro1595 modulates the effects of an HFHS diet in 5xFAD mice on peripheral and central immune profiles including CNS-associated CD8+ T cells, the composition of gut microbiota, and long-term potentiation deficits. Discussion: Obesogenic diet induces immune and neuronal dysfunction in 5xFAD mice and sTNF inhibition mitigates its effects. A clinical trial in subjects at risk for AD due to genetic predisposition and underlying inflammation associated with peripheral inflammatory co-morbidities will be needed to investigate the extent to which these findings translate to the clinic.
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Affiliation(s)
- Kathryn P. MacPherson
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Lori N. Eidson
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Madelyn C. Houser
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA, United States
| | - Blaine E. Weiss
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jenna L. Gollihue
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Mary K. Herrick
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, The University of Florida College of Medicine, Gainesville, FL, United States
| | - Maria Elizabeth de Sousa Rodrigues
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Lindsey Sniffen
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Erica M. Weekman
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Adam M. Hamilton
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Sean D. Kelly
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Danielle L. Oliver
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Yuan Yang
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Jianjun Chang
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Timothy R. Sampson
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Christopher M. Norris
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Malú Gámez Tansey
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, The University of Florida College of Medicine, Gainesville, FL, United States
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Sompol P, Gollihue JL, Weiss BE, Lin RL, Case SL, Kraner SD, Weekman EM, Gant JC, Rogers CB, Niedowicz DM, Sudduth TL, Powell DK, Lin AL, Nelson PT, Thibault O, Wilcock DM, Norris CM. Targeting Astrocyte Signaling Alleviates Cerebrovascular and Synaptic Function Deficits in a Diet-Based Mouse Model of Small Cerebral Vessel Disease. J Neurosci 2023; 43:1797-1813. [PMID: 36746627 PMCID: PMC10010459 DOI: 10.1523/jneurosci.1333-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 01/25/2023] [Accepted: 01/31/2023] [Indexed: 02/08/2023] Open
Abstract
Despite the indispensable role that astrocytes play in the neurovascular unit, few studies have investigated the functional impact of astrocyte signaling in cognitive decline and dementia related to vascular pathology. Diet-mediated induction of hyperhomocysteinemia (HHcy) recapitulates numerous features of vascular contributions to cognitive impairment and dementia (VCID). Here, we used astrocyte targeting approaches to evaluate astrocyte Ca2+ dysregulation and the impact of aberrant astrocyte signaling on cerebrovascular dysfunction and synapse impairment in male and female HHcy diet mice. Two-photon imaging conducted in fully awake mice revealed activity-dependent Ca2+ dysregulation in barrel cortex astrocytes under HHcy. Stimulation of contralateral whiskers elicited larger Ca2+ transients in individual astrocytes of HHcy diet mice compared with control diet mice. However, evoked Ca2+ signaling across astrocyte networks was impaired in HHcy mice. HHcy also was associated with increased activation of the Ca2+/calcineurin-dependent transcription factor NFAT4, which has been linked previously to the reactive astrocyte phenotype and synapse dysfunction in amyloid and brain injury models. Targeting the NFAT inhibitor VIVIT to astrocytes, using adeno-associated virus vectors, led to reduced GFAP promoter activity in HHcy diet mice and improved functional hyperemia in arterioles and capillaries. VIVIT expression in astrocytes also preserved CA1 synaptic function and improved spontaneous alternation performance on the Y maze. Together, the results demonstrate that aberrant astrocyte signaling can impair the major functional properties of the neurovascular unit (i.e., cerebral vessel regulation and synaptic regulation) and may therefore represent a promising drug target for treating VCID and possibly Alzheimer's disease and other related dementias.SIGNIFICANCE STATEMENT The impact of reactive astrocytes in Alzheimer's disease and related dementias is poorly understood. Here, we evaluated Ca2+ responses and signaling in barrel cortex astrocytes of mice fed with a B-vitamin deficient diet that induces hyperhomocysteinemia (HHcy), cerebral vessel disease, and cognitive decline. Multiphoton imaging in awake mice with HHcy revealed augmented Ca2+ responses in individual astrocytes, but impaired signaling across astrocyte networks. Stimulation-evoked arteriole dilation and elevated red blood cell velocity in capillaries were also impaired in cortex of awake HHcy mice. Astrocyte-specific inhibition of the Ca2+-dependent transcription factor, NFAT, normalized cerebrovascular function in HHcy mice, improved synaptic properties in brain slices, and stabilized cognition. Results suggest that astrocytes are a mechanism and possible therapeutic target for vascular-related dementia.
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Affiliation(s)
- Pradoldej Sompol
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
| | | | - Blaine E Weiss
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
| | - Ruei-Lung Lin
- Departments of Pharmacology and Nutritional Sciences
| | - Sami L Case
- Departments of Pharmacology and Nutritional Sciences
| | | | | | - John C Gant
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
| | | | | | | | | | - Ai-Ling Lin
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
| | - Peter T Nelson
- Sanders-Brown Center on Aging
- Pathology, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Olivier Thibault
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
| | | | - Christopher M Norris
- Sanders-Brown Center on Aging
- Departments of Pharmacology and Nutritional Sciences
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Weekman EM, Winder Z, Rogers CB, Abner EL, Sudduth TL, Patel E, Dugan AJ, Fister SX, Wasek B, Nelson PT, Jicha GA, Bottiglieri T, Fardo DW, Wilcock DM. Genetic expression changes and pathologic findings associated with hyperhomocysteinemia in human autopsy brain tissue. A&D Transl Res & Clin Interv 2022; 8:e12368. [PMID: 36514441 PMCID: PMC9732462 DOI: 10.1002/trc2.12368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 12/14/2022]
Abstract
Introduction Vascular contributions to cognitive impairment and dementia (VCID) are a leading cause of dementia. An underappreciated, modifiable risk factor for VCID is hyperhomocysteinemia (HHcy), defined by elevated levels of plasma homocysteine, most often due to impaired B vitamin absorption in aged persons. Studies aimed at identifying neuropathologic features and gene expression profiles associated with HHcy have been lacking. Methods A subset of research volunteers from the University of Kentucky Alzheimer's Disease Research Center longitudinal cohort came to autopsy and had ante mortem plasma homocysteine levels available. Brain tissue and blood plasma drawn closest to death were used to measure homocysteine and related metabolites in the current pilot study. Genetic expression profiles of inflammatory markers were evaluated using the Human Neuroinflammation NanoString panel. Further analyses included an evaluation of plasma homocysteine effects on amyloid beta, tau, ionized calcium-binding adaptor molecule 1, and glial fibrillary acidic protein immunohistochemistry in the frontal and occipital cortices. Analytes and other study outcomes were evaluated in relation to ante mortem HHcy status: We identified 13 persons with normal ante mortem plasma homocysteine levels (<14 µmol/L) and 18 who had high plasma homocysteine levels (≥14 µmol/L). Results Participants with HHcy demonstrated increased levels of several plasma homocysteine cycle metabolites such as total cysteine, S-adenosyl-homocysteine, cystathionine, and choline. Inflammatory gene expression profiles showed a general downregulation in the setting of elevated plasma homocysteine. HHcy was associated with more and longer microglial processes, but smaller and fewer astrocytes, especially in participants of older age at death. HHcy in older participants was also associated with occipital cortex microhemorrhages and increased severity of atherosclerosis throughout the cerebral vasculature. Conclusions Increased plasma homocysteine and older age were associated with the downregulation of inflammatory gene expression markers in association with significant glial and vascular pathology changes. Impaired immune function is a plausible mechanism by which HHcy increases cerebrovascular damage leading to impaired cognitive function.
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Affiliation(s)
- Erica M. Weekman
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Zach Winder
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Colin B. Rogers
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Erin L. Abner
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | | | - Ela Patel
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Adam J. Dugan
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Shuling X. Fister
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Brandi Wasek
- Baylor Scott and White Research InstituteCenter of MetabolomicsInstitute of Metabolic DiseaseDallasTexasUSA
| | - Peter T. Nelson
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Gregory A. Jicha
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Teodoro Bottiglieri
- Baylor Scott and White Research InstituteCenter of MetabolomicsInstitute of Metabolic DiseaseDallasTexasUSA
| | - David W. Fardo
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Donna M. Wilcock
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
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9
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Early AN, Weekman EM, Lee T, Wilcock DM. Contribution of astrocytic MMP9 toward progression of VCID pathology. Alzheimers Dement 2022. [DOI: 10.1002/alz.065982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Alexandria N Early
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Erica M Weekman
- University of Kentucky Lexington KY USA
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Tiffany Lee
- University of Kentucky Lexington KY USA
- Sanders‐Brown Center on Aging Lexington KY USA
| | - Donna M Wilcock
- University of Kentucky Lexington KY USA
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
- University of Kentucky College of Medicine Lexington KY USA
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Gearon MD, Early AN, Weekman EM, Lee T, Wilcock DM. Elucidating the role of MMP9 in hyperhomocysteinemia induced degradation of the neurovascular unit. Alzheimers Dement 2022. [DOI: 10.1002/alz.065886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Alexandria N Early
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Erica M Weekman
- University of Kentucky Lexington KY USA
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Tiffany Lee
- University of Kentucky Lexington KY USA
- Sanders‐Brown Center on Aging Lexington KY USA
| | - Donna M Wilcock
- University of Kentucky Lexington KY USA
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
- University of Kentucky College of Medicine Lexington KY USA
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Weekman EM, Winder Z, Rogers CB, Abner EL, Patel E, Dugan A, Fister SX, Wasek B, Bottiglieri T, Fardo DW, Wilcock DM. Evaluation of pathologies associated with hyperhomocysteinemia in human autopsy brain tissue. Alzheimers Dement 2022. [DOI: 10.1002/alz.068004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Erica M Weekman
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Zachary Winder
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Colin B Rogers
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Erin L Abner
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
- University of Kentucky College of Public Health Lexington KY USA
| | - Ela Patel
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | | | - Shuling X Fister
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
| | - Brandi Wasek
- Baylor Scott and White Health / Center of Metabolomics / Institute of Metabolic Disease Dallas TX USA
| | - Teodoro Bottiglieri
- Baylor Scott and White Health / Center of Metabolomics / Institute of Metabolic Disease Dallas TX USA
| | - David W. Fardo
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
- University of Kentucky College of Public Health Lexington KY USA
| | - Donna M Wilcock
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
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Braun DJ, Weekman EM, Gordon MN, Späni CB. Editorial: Modulation of neuroimmune systems to preserve brain function in aging and dementia. Front Neurosci 2022; 16:995409. [PMID: 35992899 PMCID: PMC9382828 DOI: 10.3389/fnins.2022.995409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- David J. Braun
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
- *Correspondence: David J. Braun
| | - Erica M. Weekman
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Marcia N. Gordon
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, East Lansing, MI, United States
| | - Claudia B. Späni
- Institute for Regenerative Medicine (IREM), University of Zürich, Zurich, Switzerland
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13
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Seaks CE, Weekman EM, Sudduth TL, Xie K, Wasek B, Fardo DW, Johnson LA, Bottiglieri T, Wilcock DM. Apolipoprotein E ε4/4 genotype limits response to dietary induction of hyperhomocysteinemia and resulting inflammatory signaling. J Cereb Blood Flow Metab 2022; 42:771-787. [PMID: 35023380 PMCID: PMC9254035 DOI: 10.1177/0271678x211069006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 10/15/2021] [Accepted: 11/17/2021] [Indexed: 01/16/2023]
Abstract
Vascular contributions to cognitive impairment and dementia (VCID) are the second leading cause of dementia behind Alzheimer's disease. Apolipoprotein E (ApoE) is a lipid transporting lipoprotein found within the brain and periphery. The APOE ε4 allele is the strongest genetic risk factor for late onset Alzheimer's disease and is a risk factor for VCID. Our lab has previously utilized a dietary model of hyperhomocysteinemia (HHcy) to induce VCID pathology and cognitive deficits in mice. This diet induces perivascular inflammation through cumulative oxidative damage leading to glial mediated inflammation and blood brain barrier breakdown. Here, we examine the impact of ApoE ε4 compared to ε3 alleles on the progression of VCID pathology and inflammation in our dietary model of HHcy. We report a significant resistance to HHcy induction in ε4 mice, accompanied by a number of related differences related to homocysteine (Hcy) metabolism and methylation cycle, or 1-C, metabolites. There were also significant differences in inflammatory profiles between ε3 and ε4 mice, as well as significant reduction in Serpina3n, a serine protease inhibitor associated with ApoE ε4, expression in ε4 HHcy mice relative to ε4 controls. Finally, we find evidence of pervasive sex differences within both genotypes in response to HHcy induction.
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Affiliation(s)
- Charles E Seaks
- Sanders-Brown Center on Aging, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY,
USA
| | - Erica M Weekman
- Sanders-Brown Center on Aging, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY,
USA
| | | | - Kevin Xie
- Department of Biostatistics, University of Kentucky, Lexington,
KY, USA
| | - Brandi Wasek
- Center of Metabolomics, Institute of Metabolic Disease, Baylor
Scott & White Research Institute, Dallas, TX, USA
| | - David W Fardo
- Sanders-Brown Center on Aging, Lexington, KY, USA
- Department of Biostatistics, University of Kentucky, Lexington,
KY, USA
| | - Lance A Johnson
- Sanders-Brown Center on Aging, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY,
USA
| | - Teodoro Bottiglieri
- Center of Metabolomics, Institute of Metabolic Disease, Baylor
Scott & White Research Institute, Dallas, TX, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY,
USA
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Weekman EM, Lee T, Price BR, Woolums AE, Hawthorne D, Seaks CE, Wilcock DM. Time course of neuropathologic changes in hyperhomocysteinemia‐induced VCID. Alzheimers Dement 2021. [DOI: 10.1002/alz.051364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Erica M Weekman
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Tiffany Lee
- University of Kentucky Lexington KY USA
- Sanders‐Brown Center on Aging Lexington KY USA
| | - Brittani R Price
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Abigail E Woolums
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Danielle Hawthorne
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Charles E Seaks
- University of Kentucky Lexington KY USA
- Sanders Brown Center on Aging Lexington KY USA
| | - Donna M Wilcock
- University of Kentucky Lexington KY USA
- Sanders‐Brown Center on Aging Lexington KY USA
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Seaks CE, Weekman EM, Sudduth TL, Bottiglieri T, Johnson LA, Wilcock DM. Apolipoprotein E genotypes modulate neuroinflammatory and vascular pathology in hyperhomocysteinemia‐induced VCID. Alzheimers Dement 2021. [DOI: 10.1002/alz.056151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Kloske CM, Dugan AJ, Weekman EM, Winder Z, Patel E, Nelson PT, Fardo DW, Wilcock DM. Inflammatory Pathways Are Impaired in Alzheimer Disease and Differentially Associated With Apolipoprotein E Status. J Neuropathol Exp Neurol 2021; 80:922-932. [PMID: 34486652 PMCID: PMC8557334 DOI: 10.1093/jnen/nlab085] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Alzheimer disease (AD) is a neurodegenerative disease characterized by a cognitive decline leading to dementia. The most impactful genetic risk factor is apolipoprotein E (APOE). APOE-ε4 significantly increases AD risk, APOE-ε3 is the most common gene variant, and APOE-ε2 protects against AD. However, the underlying mechanisms of APOE-ε4 on AD risk remains unclear, with APOE-ε4 impacting many pathways. We investigated how the APOE isoforms associated with the neuroinflammatory state of the brain with and without AD pathology. Frozen brain tissue from the superior and middle temporal gyrus was analyzed from APOE-ε3/3 (n = 9) or APOE-ε4/4 (n = 10) participants with AD pathology and APOE-ε3/3 (n = 9) participants without AD pathology. We determined transcript levels of 757 inflammatory related genes using the NanoString Human Neuroinflammation Panel. We found significant pathways impaired in APOE-ε4/4-AD individuals compared to APOE-ε3/3-AD. Of interest, expression of genes related to microglial activation (SALL1), motility (FSCN1), epigenetics (DNMT1), and others showed altered expression. Additionally, we performed immunohistochemistry of P2RY12 to confirm reduced microglial activation. Our results suggest APOE-ε3 responds to AD pathology while potentially having a harmful long-term inflammatory response, while APOE-ε4 shows a weakened response to pathology. Overall, APOE isoforms appear to modulate the brain immune response to AD-type pathology.
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Affiliation(s)
- Courtney M Kloske
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Adam J Dugan
- Department of Biostatistics, College of Public Health, University of Kentucky, Lexington, Kentucky, USA
| | - Erica M Weekman
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Zachary Winder
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Ela Patel
- Department of Pathology and Laboratory Medicine, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Peter T Nelson
- Department of Pathology and Laboratory Medicine, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - David W Fardo
- Department of Biostatics, Sanders-Brown Center on Aging, College of Public Health, University of Kentucky, Lexington, Kentucky, USA
| | - Donna M Wilcock
- From the Department of Physiology, Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
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Linton AE, Weekman EM, Wilcock DM. Pathologic sequelae of vascular cognitive impairment and dementia sheds light on potential targets for intervention. Cerebral Circulation - Cognition and Behavior 2021; 2:100030. [PMID: 36324710 PMCID: PMC9616287 DOI: 10.1016/j.cccb.2021.100030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/11/2021] [Accepted: 10/08/2021] [Indexed: 11/30/2022]
Abstract
VCID is one of the leading causes of dementia and yet limited therapeutic approaches are in development. This review discusses our current understanding of the pathophysiology of VCID with a focus on inflammation and matrix metalloproteinases. The review highlights several potential therapeutic targets based on the pathophysiologies described.
Vascular contributions to cognitive impairment and dementia (VCID) is one of the leading causes of dementia along with Alzheimer's disease (AD) and, importantly, VCID often manifests as a comorbidity of AD(Vemuri and Knopman 2016; Schneider and Bennett 2010)(Vemuri and Knopman 2016; Schneider and Bennett 2010). Despite its common clinical manifestation, the mechanisms underlying VCID disease progression remains elusive. In this review, existing knowledge is used to propose a novel hypothesis linking well-established risk factors of VCID with the distinct neurodegenerative cascades of neuroinflammation and chronic hypoperfusion. It is hypothesized that these two synergistic signaling cascades coalesce to initiate aberrant angiogenesis and induce blood brain barrier breakdown trough a mechanism mediated by vascular growth factors and matrix metalloproteinases respectively. Finally, this review concludes by highlighting several potential therapeutic interventions along this neurodegenerative sequalae providing diverse opportunities for future translational study.
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Affiliation(s)
- Erica M. Weekman
- University of Kentucky, Sanders Brown Center on Aging Lexington KY USA
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Price BR, Sudduth TL, Weekman EM, Johnson S, Hawthorne D, Woolums A, Wilcock DM. Therapeutic Trem2 activation ameliorates amyloid-beta deposition and improves cognition in the 5XFAD model of amyloid deposition. J Neuroinflammation 2020; 17:238. [PMID: 32795308 PMCID: PMC7427742 DOI: 10.1186/s12974-020-01915-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Triggering receptor expressed on myeloid cell-2 (TREM2) is a lipid and lipoprotein binding receptor expressed by cells of myeloid origin. Homozygous TREM2 mutations cause early onset progressive presenile dementia while heterozygous, point mutations triple the risk of Alzheimer's disease (AD). Although human genetic findings support the notion that loss of TREM2 function exacerbates neurodegeneration, it is not clear whether activation of TREM2 in a disease state would result in therapeutic benefits. To determine the viability of TREM2 activation as a therapeutic strategy, we sought to characterize an agonistic Trem2 antibody (AL002a) and test its efficacy and mechanism of action in an aggressive mouse model of amyloid deposition. METHODS To determine whether agonism of Trem2 results in therapeutic benefits, we designed both intracranial and systemic administration studies. 5XFAD mice in the intracranial administration study were assigned to one of two injection groups: AL002a, a Trem2-agonizing antibody, or MOPC, an isotype-matched control antibody. Mice were then subject to a single bilateral intracranial injection into the frontal cortex and hippocampus and euthanized 72 h later. The tissue from the left hemisphere was histologically examined for amyloid-beta and microglia activation, whereas the tissue from the right hemisphere was used for biochemical analyses. Similarly, mice in the systemic administration study were randomized to one of the aforementioned injection groups and the assigned antibody was administered intraperitoneally once a week for 14 weeks. Mice underwent behavioral assessment between the 12- and 14-week timepoints and were euthanized 24 h after their final injection. The tissue from the left hemisphere was used for histological analyses whereas the tissue from the right hemisphere was used for biochemical analyses. RESULTS Here, we show that chronic activation of Trem2, in the 5XFAD mouse model of amyloid deposition, leads to reversal of the amyloid-associated gene expression signature, recruitment of microglia to plaques, decreased amyloid deposition, and improvement in spatial learning and novel object recognition memory. CONCLUSIONS These findings indicate that Trem2 activators may be effective for the treatment of AD and possibly other neurodegenerative disorders.
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Affiliation(s)
- Brittani R Price
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Tiffany L Sudduth
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Erica M Weekman
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Sherika Johnson
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Danielle Hawthorne
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Abigail Woolums
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA.
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
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Weekman EM, Sudduth TL, Price BR, Woolums AE, Hawthorne D, Seaks CE, Wilcock DM. Time course of neuropathological events in hyperhomocysteinemic amyloid depositing mice reveals early neuroinflammatory changes that precede amyloid changes and cerebrovascular events. J Neuroinflammation 2019; 16:284. [PMID: 31888650 PMCID: PMC6937663 DOI: 10.1186/s12974-019-1685-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 12/19/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Vascular contributions to cognitive impairment and dementia (VCID) are the second leading cause of dementia behind only Alzheimer's disease (AD); however, VCID is commonly found as a co-morbidity with sporadic AD. We have previously established a mouse model of VCID by inducing hyperhomocysteinemia in both wild-type and amyloid depositing mice. While we have shown the time course of neuropathological events in the wild-type mice with hyperhomocysteinemia, the effect of amyloid deposition on this time course remains unknown; therefore, in this study, we determined the time course of neuropathological changes in our mouse model of hyperhomocysteinemia-induced VCID in amyloid depositing mice. METHODS APP/PS1 mice were placed on either a diet deficient in folate and vitamins B6 and B12 and enriched in methionine to induce hyperhomocysteinemia or a control diet for 2, 6, 10, 14, or 18 weeks. Immunohistochemistry and gene expression analysis were used to determine neuroinflammatory changes. Microhemorrhages and amyloid deposition were analyzed using histology and, finally, behavior was assessed using the 2-day radial arm water maze. RESULTS Neuroinflammation, specifically a pro-inflammatory phenotype, was the first pathological change to occur. Specifically, we see a significant increase in gene expression of tumor necrosis factor alpha, interleukin 1 beta, interleukin 6, and interleukin 12a by 6 weeks. This was followed by cognitive deficits starting at 10 weeks. Finally, there is a significant increase in the number of microhemorrhages at 14 weeks on diet as well as redistribution of amyloid from the parenchyma to the vasculature. CONCLUSIONS The time course of these pathologies points to neuroinflammation as the initial, key player in homocysteine-induced VCID co-morbid with amyloid deposition and provides a possible therapeutic target and time points.
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Affiliation(s)
- Erica M Weekman
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Tiffany L Sudduth
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Brittani R Price
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Abigail E Woolums
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Danielle Hawthorne
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Charles E Seaks
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY, 40536, USA.
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Price BR, Sudduth TL, Weekman EM, Woolums A, Hawthorne D, Rosenthal A, Wilcock DM. O1‐08‐01: THERAPEUTIC TARGETING OF TREM2 BY AN ACTIVATING ANTIBODY AMELIORATES AMYLOID‐BETA DEPOSITION AND IMPROVES COGNITION IN THE 5XFAD MODEL OF ALZHEIMER'S DISEASE. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.4559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Price BR, Wilcock DM, Weekman EM. Hyperhomocysteinemia as a Risk Factor for Vascular Contributions to Cognitive Impairment and Dementia. Front Aging Neurosci 2018; 10:350. [PMID: 30429785 PMCID: PMC6220027 DOI: 10.3389/fnagi.2018.00350] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/16/2018] [Indexed: 12/19/2022] Open
Abstract
Behind only Alzheimer's disease, vascular contributions to cognitive impairment and dementia (VCID) is the second most common cause of dementia, affecting roughly 10-40% of dementia patients. While there is no cure for VCID, several risk factors for VCID, such as diabetes, hypertension, and stroke, have been identified. Elevated plasma levels of homocysteine, termed hyperhomocysteinemia (HHcy), are a major, yet underrecognized, risk factor for VCID. B vitamin deficiency, which is the most common cause of HHcy, is common in the elderly. With B vitamin supplementation being a relatively safe and inexpensive therapeutic, the treatment of HHcy-induced VCID would seem straightforward; however, preclinical and clinical data shows it is not. Clinical trials using B vitamin supplementation have shown conflicting results about the benefits of lowering homocysteine and issues have arisen over proper study design within the trials. Studies using cell culture and animal models have proposed several mechanisms for homocysteine-induced cognitive decline, providing other targets for therapeutics. For this review, we will focus on HHcy as a risk factor for VCID, specifically, the different mechanisms proposed for homocysteine-induced cognitive decline and the clinical trials aimed at lowering plasma homocysteine.
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Affiliation(s)
| | | | - Erica M. Weekman
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
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23
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Abstract
High plasma levels of homocysteine, termed hyperhomocysteinemia, are a risk factor for vascular cognitive impairment and dementia, which is the second leading cause of dementia. While hyperhomocysteinemia induces microhemorrhages and cognitive decline in mice, the specific effect of hyperhomocysteinemia on each cell type remains unknown. We took separate cultures of astrocytes, microglia, endothelial cells, and neuronal cells and treated each with moderate levels of homocysteine for 24, 48, 72, and 96 hr. We then determined the gene expression changes for cell-specific markers and neuroinflammatory markers including the matrix metalloproteinase 9 system. Astrocytes had decreased levels of several astrocytic end feet genes, such as aquaporin 4 and an adenosine triphosphate (ATP)-sensitive inward rectifier potassium channel at 72 hr, as well as an increase in matrix metalloproteinase 9 at 48 hr. Gene changes in microglia indicated a peak in proinflammatory markers at 48 hr followed by a peak in the anti-inflammatory marker, interleukin 1 receptor antagonist, at 72 hr. Endothelial cells had reduced occludin expression at 72 hr, while kinases and phosphatases known to alter tau phosphorylation states were increased in neuronal cells. This suggests that hyperhomocysteinemia induces early proinflammatory changes in microglia and astrocytic changes relevant to their interaction with the vasculature. Overall, the data show how hyperhomocysteinemia could impact Alzheimer’s disease and vascular cognitive impairment and dementia.
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Affiliation(s)
- Erica M Weekman
- 1 Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA.,2 Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Abigail E Woolums
- 1 Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Tiffany L Sudduth
- 1 Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Donna M Wilcock
- 1 Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA.,2 Department of Physiology, University of Kentucky, Lexington, KY, USA
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Price BR, Sudduth TL, Weekman EM, Wilcock DM, Woolums A. [P1–198]: ASTROCYTE RESPONSE TO HYPERHOMOCYSTEINEMIA (HHCY). Alzheimers Dement 2017. [DOI: 10.1016/j.jalz.2017.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | | | | | - Donna M. Wilcock
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKYUSA
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Abstract
The neurovascular unit, which consists of astrocytic end-feet, neurons, pericytes, and endothelial cells, plays a key role in maintaining brain homeostasis by forming the blood-brain barrier and carefully controlling local cerebral blood flow. When the blood-brain barrier is disrupted, blood components can leak into the brain, damage the surrounding tissue and lead to cognitive impairment. This disruption in the blood-brain barrier and subsequent impairment in cognition are common after stroke and during cerebral amyloid angiopathy and Alzheimer's disease. Matrix metalloproteinases are proteases that degrade the extracellular matrix as well as tight junctions between endothelial cells and have been implicated in blood-brain barrier breakdown in neurodegenerative diseases. This review will focus on the roles of MMP2 and MMP9 in dementia, primarily post-stroke events that lead to dementia, cerebral amyloid angiopathy, and Alzheimer's disease.
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Hainsworth AH, Yeo NE, Weekman EM, Wilcock DM. Homocysteine, hyperhomocysteinemia and vascular contributions to cognitive impairment and dementia (VCID). Biochim Biophys Acta Mol Basis Dis 2015; 1862:1008-17. [PMID: 26689889 DOI: 10.1016/j.bbadis.2015.11.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/27/2015] [Accepted: 11/29/2015] [Indexed: 11/29/2022]
Abstract
Homocysteine is produced physiologically in all cells, and is present in plasma of healthy individuals (plasma [HCy]: 3-10μM). While rare genetic mutations (CBS, MTHFR) cause severe hyperhomocysteinemia ([HCy]: 100-200μM), mild-moderate hyperhomocysteinemia ([HCy]: 10-100μM) is common in older people, and is an independent risk factor for stroke and cognitive impairment. As B-vitamin supplementation (B6, B12 and folate) has well-validated homocysteine-lowering efficacy, this may be a readily-modifiable risk factor in vascular contributions to cognitive impairment and dementia (VCID). Here we review the biochemical and cellular actions of HCy related to VCID. Neuronal actions of HCy were at concentrations above the clinically-relevant range. Effects of HCy <100μM were primarily vascular, including myocyte proliferation, vessel wall fibrosis, impaired nitric oxide signalling, superoxide generation and pro-coagulant actions. HCy-lowering clinical trials relevant to VCID are discussed. Extensive clinical and preclinical data support HCy as a mediator for VCID. In our view further trials of combined B-vitamin supplementation are called for, incorporating lessons from previous trials and from recent experimental work. To maximise likelihood of treatment effect, a future trial should: supply a high-dose, combination supplement (B6, B12 and folate); target the at-risk age range; and target cohorts with low baseline B-vitamin status. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.
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Affiliation(s)
- Atticus H Hainsworth
- Cardiovascular and Cell Sciences Research Centre, St Georges University of London, London SW17 0RE, UK.
| | - Natalie E Yeo
- Cardiovascular and Cell Sciences Research Centre, St Georges University of London, London SW17 0RE, UK
| | - Erica M Weekman
- Sanders-Brown Center on Aging, University of Kentucky, Lexington KY 40536, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, University of Kentucky, Lexington KY 40536, USA.
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Weekman EM, Kopper TJ, Sudduth TL, Wilcock DM. O1‐05‐06: Reduced efficacy of anti‐Aβ immunotherapy in a mouse model of amyloid deposition and vascular cognitive impairment co‐morbidity. Alzheimers Dement 2015. [DOI: 10.1016/j.jalz.2015.07.481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Latta CH, Sudduth TL, Weekman EM, Brothers HM, Abner EL, Popa GJ, Mendenhall MD, Gonzalez-Oregon F, Braun K, Wilcock DM. Determining the role of IL-4 induced neuroinflammation in microglial activity and amyloid-β using BV2 microglial cells and APP/PS1 transgenic mice. J Neuroinflammation 2015; 12:41. [PMID: 25885682 PMCID: PMC4350455 DOI: 10.1186/s12974-015-0243-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 01/10/2015] [Indexed: 12/16/2022] Open
Abstract
Background Microglia are considered the resident immune cells of the central nervous system (CNS). In response to harmful stimuli, an inflammatory reaction ensues in which microglia are activated in a sequenced spectrum of pro- and antiinflammatory phenotypes that are akin to the well-characterized polarization states of peripheral macrophages. A “classically” activated M1 phenotype is known to eradicate toxicity. The transition to an “alternatively” activated M2 phenotype encompasses neuroprotection and repair. In recent years, inflammation has been considered an accompanying pathology in response to the accumulation of extracellular amyloid-β (Aβ) in Alzheimer’s disease (AD). This study aimed to drive an M2a-biased immune phenotype with IL-4 in vitro and in vivo and to determine the subsequent effects on microglial activation and Aβ pathology. Methods In vitro, exogenous IL-4 was applied to BV2 microglial cell cultures to evaluate the temporal progression of microglial responses. In vivo, intracranial injections of an adeno-associate-virus (AAV) viral vector were performed to assess long-term expression of IL-4 in the frontal cortex and hippocampus of Aβ-depositing, APP/PS1 transgenic mice. Quantitative real-time PCR was used to assess the fold change in expression of biomarkers representing each of the microglial phenotypes in both the animal tissue and the BV2 cells. ELISAs quantified IL-4 expression and Aβ levels. Histological staining permitted quantification of microglial and astrocytic activity. Results Both in vitro and in vivo models showed an enhanced M2a phenotype, and the in vivo model revealed a trend toward a decreased trend in Aβ deposition. Conclusions In summary, this study offers insight into the therapeutic potential of microglial immune response in AD.
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Affiliation(s)
- Clare H Latta
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Biology, The University of Manchester, Manchester, M13 9PL, UK.
| | - Tiffany L Sudduth
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA.
| | - Erica M Weekman
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
| | - Holly M Brothers
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA.
| | - Erin L Abner
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Epidemiology, University of Kentucky, Lexington, KY, 40536, USA.
| | - Gabriel J Popa
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA.
| | - Michael D Mendenhall
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA.
| | - Floracita Gonzalez-Oregon
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
| | - Kaitlyn Braun
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
| | - Donna M Wilcock
- Department of Physiology, University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY, 40536, USA. .,Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA. .,University of Kentucky, Room 424 Sanders-Brown Center on Aging, 800 S Limestone Street, Lexington, KY, 40536, USA.
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Weekman EM, Sudduth TL, Wilcock DM. Abstract T P221: Anti-amyloid Immunotherapy Results in Exacerbation of Cerebrovascular Disease Through Activation of Matrix Metalloproteinases. Stroke 2015. [DOI: 10.1161/str.46.suppl_1.tp221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cerebrovascular disease is frequently co-morbid with Alzheimer’s disease (AD) and we hypothesize this co-morbidity could complicate the development of disease-modifying therapies. The amyloid-beta (Aβ) peptide has been the intense focus of therapeutic development for the treatment of AD. One therapeutic approach uses passive immunization against Aβ using anti-Aβ antibodies. We further hypothesize that inflammation mediated activation of MMP9 and MMP2 lead to the exacerbation of cerebrovascular pathologies following immunotherapy. To test our hypothesis we took aged 21 month old APP transgenic mice (PDAPP mice) that have cerebral amyloid angiopathy (CAA) and disruptions of the blood-brain barrier and administered anti-Aβ antibody or control IgG2a for 8 weeks at a dose of 12.5mg/kg. Expression of the MMP2 and MMP9 families were measured by qPCR and Western blot, total Aβ, CAA and albumin for vasogenic edema were measured using immunohistochemistry, and finally, microhemorrhages were assessed with Prussian blue staining.
Treatment with the anti-Aβ antibody resulted in significantly decreased Aβ in the frontal cortex and hippocampus. Further, we found increased microhemorrhage associated with increased gene expression of MMP9, MMP2 and MMP14 (the activator of MMP2). Assessment of vasogenic edema, as well as CAA and inflammatory states is currently ongoing.
Overall, while anti-Aβ treatment leads to decreased Aβ, cerebrovascular pathologies, most notably microhemorrhages, are increased by immunotherapy. This increased microhemorrhage is associated with increased MMP2 and MMP9 expression. These data suggest that co-morbidity of cerebrovascular pathologies with AD will significantly impair efficacy of therapeutics for AD and could potentially lead to adverse events.
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Weekman EM, Sudduth TL, Abner EL, Popa GJ, Mendenhall MD, Brothers HM, Braun K, Greenstein A, Wilcock DM. Transition from an M1 to a mixed neuroinflammatory phenotype increases amyloid deposition in APP/PS1 transgenic mice. J Neuroinflammation 2014; 11:127. [PMID: 25062954 PMCID: PMC4128532 DOI: 10.1186/1742-2094-11-127] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 06/22/2014] [Indexed: 11/22/2022] Open
Abstract
Background The polarization to different neuroinflammatory phenotypes has been described in early Alzheimer’s disease, yet the impact of these phenotypes on amyloid-beta (Aβ) pathology remains unknown. Short-term studies show that induction of an M1 neuroinflammatory phenotype reduces Aβ, but long-term studies have not been performed that track the neuroinflammatory phenotype. Methods Wild-type and APP/PS1 transgenic mice aged 3 to 4 months received a bilateral intracranial injection of adeno-associated viral (AAV) vectors expressing IFNγ or green fluorescent protein in the frontal cortex and hippocampus. Mice were sacrificed 4 or 6 months post-injection. ELISA measurements were used for IFNγ protein levels and biochemical levels of Aβ. The neuroinflammatory phenotype was determined through quantitative PCR. Microglia, astrocytes, and Aβ levels were assessed with immunohistochemistry. Results AAV expressing IFNγ induced an M1 neuroinflammatory phenotype at 4 months and a mixed phenotype along with an increase in Aβ at 6 months. Microglial staining was increased at 6 months and astrocyte staining was decreased at 4 and 6 months in mice receiving AAV expressing IFNγ. Conclusions Expression of IFNγ through AAV successfully induced an M1 phenotype at 4 months that transitioned to a mixed phenotype by 6 months. This transition also appeared with an increase in amyloid burden suggesting that a mixed phenotype, or enhanced expression of M2a and M2c markers, could contribute to increasing amyloid burden and disease progression.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Donna M Wilcock
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.
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Sudduth TL, Weekman EM, Brothers HM, Braun K, Wilcock DM. β-amyloid deposition is shifted to the vasculature and memory impairment is exacerbated when hyperhomocysteinemia is induced in APP/PS1 transgenic mice. Alzheimers Res Ther 2014; 6:32. [PMID: 24991237 PMCID: PMC4078260 DOI: 10.1186/alzrt262] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/21/2014] [Indexed: 11/17/2022]
Abstract
Introduction Vascular dementia is the second most common cause of dementia after Alzheimer’s disease (AD). In addition, it is estimated that almost half of all AD patients have significant cerebrovascular disease comorbid with their AD pathology. We hypothesized that cerebrovascular disease significantly impacts AD pathological progression. Methods We used a dietary model of cerebrovascular disease that relies on the induction of hyperhomocysteinemia (HHcy). HHcy is a significant clinical risk factor for stroke, cardiovascular disease and type 2 diabetes. In the present study, we induced HHcy in APP/PS1 transgenic mice. Results While total β-amyloid (Aβ) load is unchanged across groups, Congophilic amyloid deposition was decreased in the parenchyma and significantly increased in the vasculature as cerebral amyloid angiopathy (CAA; vascular amyloid deposition) in HHcy APP/PS1 mice. We also found that HHcy induced more microhemorrhages in the APP/PS1 mice than in the wild-type mice and that it switched the neuroinflammatory phenotype from an M2a biased state to an M1 biased state. Associated with these changes was an induction of the matrix metalloproteinase protein 2 (MMP2) and MMP9 systems. Interestingly, after 6 months of HHcy, the APP/PS1 mice were cognitively worse than wild-type HHcy mice or APP/PS1 mice, indicative of an additive effect of the cerebrovascular pathology and amyloid deposition. Conclusions These data show that cerebrovascular disease can significantly impact Aβ distribution in the brain, favoring vascular deposition. We predict that the presence of cerebrovascular disease with AD will have a significant impact on AD progression and the efficacy of therapeutics.
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Affiliation(s)
- Tiffany L Sudduth
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY 40536, USA
| | - Erica M Weekman
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY 40536, USA
| | - Holly M Brothers
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY 40536, USA
| | - Kaitlyn Braun
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY 40536, USA
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St., Lexington, KY 40536, USA
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