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Nehra G, Promsan S, Yubolphan R, Chumboatong W, Vivithanaporn P, Maloney BJ, Lungkaphin A, Bauer B, Hartz AMS. Cognitive decline, Aβ pathology, and blood-brain barrier function in aged 5xFAD mice. Fluids Barriers CNS 2024; 21:29. [PMID: 38532486 PMCID: PMC10967049 DOI: 10.1186/s12987-024-00531-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 03/18/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND Patients with Alzheimer's disease (AD) develop blood-brain barrier dysfunction to varying degrees. How aging impacts Aβ pathology, blood-brain barrier function, and cognitive decline in AD remains largely unknown. In this study, we used 5xFAD mice to investigate changes in Aβ levels, barrier function, and cognitive decline over time. METHODS 5xFAD and wild-type (WT) mice were aged between 9.5 and 15.5 months and tested for spatial learning and reference memory with the Morris Water Maze (MWM). After behavior testing, mice were implanted with acute cranial windows and intravenously injected with fluorescent-labeled dextrans to assess their in vivo distribution in the brain by two-photon microscopy. Images were processed and segmented to obtain intravascular intensity, extravascular intensity, and vessel diameters as a measure of barrier integrity. Mice were sacrificed after in vivo imaging to isolate brain and plasma for measuring Aβ levels. The effect of age and genotype were evaluated for each assay using generalized or cumulative-linked logistic mixed-level modeling and model selection by Akaike Information Criterion (AICc). Pairwise comparisons were used to identify outcome differences between the two groups. RESULTS 5xFAD mice displayed spatial memory deficits compared to age-matched WT mice in the MWM assay, which worsened with age. Memory impairment was evident in 5xFAD mice by 2-threefold higher escape latencies, twofold greater cumulative distances until they reach the platform, and twice as frequent use of repetitive search strategies in the pool when compared with age-matched WT mice. Presence of the rd1 allele worsened MWM performance in 5xFAD mice at all ages but did not alter the rate of learning or probe trial outcomes. 9.5-month-old 15.5-month-old 5xFAD mice had twofold higher brain Aβ40 and Aβ42 levels (p < 0.001) and 2.5-fold higher (p = 0.007) plasma Aβ40 levels compared to 9.5-month-old 5xFAD mice. Image analysis showed that vessel diameters and intra- and extravascular dextran intensities were not significantly different in 9.5- and 15.5-month-old 5xFAD mice compared to age-matched WT mice. CONCLUSION 5xFAD mice continue to develop spatial memory deficits and increased Aβ brain levels while aging. Given in vivo MP imaging limitations, further investigation with smaller molecular weight markers combined with advanced imaging techniques would be needed to reliably assess subtle differences in barrier integrity in aged mice.
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Affiliation(s)
- Geetika Nehra
- Sanders-Brown Center On Aging, University of Kentucky, 760 Press Ave, 124 HKRB, Lexington, KY, 40536-0679, USA
| | - Sasivimon Promsan
- Sanders-Brown Center On Aging, University of Kentucky, 760 Press Ave, 124 HKRB, Lexington, KY, 40536-0679, USA
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Ruedeemars Yubolphan
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Faculty of Medicine Ramathibodi Hospital, Chakri Naruebodindra Medical Institute, Mahidol University, Nakhon Pathom, Thailand
| | - Wijitra Chumboatong
- Sanders-Brown Center On Aging, University of Kentucky, 760 Press Ave, 124 HKRB, Lexington, KY, 40536-0679, USA
| | - Pornpun Vivithanaporn
- Faculty of Medicine Ramathibodi Hospital, Chakri Naruebodindra Medical Institute, Mahidol University, Nakhon Pathom, Thailand
| | - Bryan J Maloney
- Sanders-Brown Center On Aging, University of Kentucky, 760 Press Ave, 124 HKRB, Lexington, KY, 40536-0679, USA
| | - Anusorn Lungkaphin
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Bjoern Bauer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, USA
| | - Anika M S Hartz
- Sanders-Brown Center On Aging, University of Kentucky, 760 Press Ave, 124 HKRB, Lexington, KY, 40536-0679, USA.
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, USA.
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Cipolla J, Jiang H, Simms AG, Baumel B, Rundek T, Wang J. Impaired Retinal Capillary Function in Patients With Alzheimer Disease. J Neuroophthalmol 2024; 44:30-34. [PMID: 37459384 PMCID: PMC10792098 DOI: 10.1097/wno.0000000000001954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2023]
Abstract
BACKGROUND Extensive evidence indicates that vasculopathy, especially the level of microcirculation, contributes to neurodegeneration in Alzheimer disease (AD). However, it is not easy to directly monitor cerebral microcirculation. The retinal microvasculature has been proposed as a surrogate measure to study cerebral vascular changes. Indeed, decreased retinal microvascular network densities were reported in patients with AD. We sought to determine the retinal capillary function (RCF, the efficiency of blood flow transferring in the capillary network) in patients with AD. METHODS Twenty patients (age 60-84 years, mean ± SD: 72.8 ± 7.7 years) with AD and 14 age-matched cognitively normal controls (CN, age 62-81 years, mean ± SD: 68.6 ± 6.7 years.) were recruited. There were no differences in vascular risk factors, including smoking, hypertension, hyperlipidemia, Type 2 diabetes, and cardiovascular disease, between the groups. One eye of each subject in both groups was imaged. Retinal blood flow (RBF) was measured using a retinal function imager, and retinal capillary density (RCD, expressed as fractal dimension Dbox) was measured using optical coherence tomography angiography. RCF was defined as the ratio of RBF to RCD. RESULTS RCF was 1.62 ± 0.56 nl/s/Dbox (mean ± SD) in the AD group, which was significantly lower than that (2.56 ± 0.25 nl/s/Dbox, P < 0.01) in the CN group. The change of RCF in the AD group represented 28% lower than in the CN group. RCF was significantly and positively correlated with RBF in the AD group (r = 0.98, P < 0.05) and in the CN group (r = 0.65, P < 0.05). CONCLUSIONS Our study is the first to demonstrate impaired retinal capillary function in patients with AD. The alteration of RCF was mainly due to decreased retinal blood flow, which is transferred by the capillary network. The RCF may be developed as a biomarker of impaired cerebral microcirculation in patients with AD.
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Affiliation(s)
- Jack Cipolla
- University of Miami Miller School of Medicine, Miami, FL, USA
| | - Hong Jiang
- University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
- The University of Miami Evelyn F. McKnight Brain Institute, Miami, FL, USA
| | - Ava-Gaye Simms
- University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Bernard Baumel
- University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Tatjana Rundek
- University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
- The University of Miami Evelyn F. McKnight Brain Institute, Miami, FL, USA
| | - Jianhua Wang
- University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
- The University of Miami Evelyn F. McKnight Brain Institute, Miami, FL, USA
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Madsen LS, Kjeldsen PL, Ismail R, Parbo P, Østergaard L, Brooks DJ, Eskildsen SF. Capillary dysfunction in healthy elderly APOE ε4 carriers with raised brain Aβ deposition. Alzheimers Dement 2024; 20:459-471. [PMID: 37679610 PMCID: PMC10917038 DOI: 10.1002/alz.13461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/26/2023] [Accepted: 08/13/2023] [Indexed: 09/09/2023]
Abstract
INTRODUCTION Capillary dysfunction, characterized by disturbances in capillary blood flow distribution, might be an overlooked factor in the development of Alzheimer's disease (AD). This study investigated microvascular blood flow in preclinical and prodromal AD individuals. METHODS Using dynamic susceptibility contrast magnetic resonance imaging and positron emission tomography, we examined alterations in microvascular circulation and levels of Aβ deposition in two independent cohorts of APOE ε4 carriers. RESULTS Capillary dysfunction was elevated in both prodromal and preclinical AD individuals compared to age-matched controls. Additionally, the prodromal group exhibited higher levels of capillary dysfunction compared to the preclinical group. DISCUSSION These findings suggest that capillary dysfunction can be detected at the preclinical stage of AD and indicates a worsening of capillary dysfunction throughout the AD continuum. Understanding the interaction between capillary dysfunction and Aβ could provide insights into the relationship between cardiovascular risk factors and the development of AD. HIGHLIGHTS Alzheimer's disease (AD) is associated with disturbances in microvascular circulation. Capillary dysfunction can be detected in preclinical AD. As cognitive symptoms progress in prodromal AD, capillary dysfunction worsens. Capillary dysfunction may impede the clearance of beta-amyloid (Aβ). Capillary dysfunction might contribute to the development of AD.
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Affiliation(s)
- Lasse S. Madsen
- Center of Functionally Integrative NeuroscienceDepartment of Clinical MedicineAarhus UniversityAarhusDenmark
- Department of Nuclear Medicine and PET‐CentreAarhus University HospitalAarhusDenmark
| | - Pernille L. Kjeldsen
- Department of Nuclear Medicine and PET‐CentreAarhus University HospitalAarhusDenmark
| | - Rola Ismail
- Department of Nuclear MedicineSygehus LillebaeltVejleDenmark
| | - Peter Parbo
- Department of Nuclear MedicineOdense University HospitalOdenseDenmark
| | - Leif Østergaard
- Center of Functionally Integrative NeuroscienceDepartment of Clinical MedicineAarhus UniversityAarhusDenmark
- Department of NeuroradiologyAarhus University HospitalAarhusDenmark
| | - David J. Brooks
- Department of Nuclear Medicine and PET‐CentreAarhus University HospitalAarhusDenmark
- Institute of Translational and Clinical ResearchUniversity of Newcastle upon TyneNewcastle upon TyneUK
| | - Simon F. Eskildsen
- Center of Functionally Integrative NeuroscienceDepartment of Clinical MedicineAarhus UniversityAarhusDenmark
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Marcolini S, Mondragón JD, Bron EE, Biessels GJ, Claassen JA, Papma JM, Middelkoop H, Dierckx RA, Borra RJ, Ramakers IH, van der Flier WM, Maurits NM, De Deyn PP. Small vessel disease burden and functional brain connectivity in mild cognitive impairment. CEREBRAL CIRCULATION - COGNITION AND BEHAVIOR 2023; 6:100192. [PMID: 38174052 PMCID: PMC10758699 DOI: 10.1016/j.cccb.2023.100192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/15/2023] [Accepted: 11/27/2023] [Indexed: 01/05/2024]
Abstract
Background The role of small vessel disease in the development of dementia is not yet completely understood. Functional brain connectivity has been shown to differ between individuals with and without cerebral small vessel disease. However, a comprehensive measure of small vessel disease quantifying the overall damage on the brain is not consistently used and studies using such measure in mild cognitive impairment individuals are missing. Method Functional brain connectivity differences were analyzed between mild cognitive impairment individuals with absent or low (n = 34) and high (n = 34) small vessel disease burden using data from the Parelsnoer Institute, a Dutch multicenter study. Small vessel disease was characterized using an ordinal scale considering: lacunes, microbleeds, perivascular spaces in the basal ganglia, and white matter hyperintensities. Resting state functional MRI data using 3 Tesla scanners was analyzed with group-independent component analysis using the CONN toolbox. Results Functional connectivity between areas of the cerebellum and between the cerebellum and the thalamus and caudate nucleus was higher in the absent or low small vessel disease group compared to the high small vessel disease group. Conclusion These findings might suggest that functional connectivity of mild cognitive impairment individuals with low or absent small vessel disease burden is more intact than in mild cognitive impairment individuals with high small vessel disease. These brain areas are mainly responsible for motor, attentional and executive functions, domains which in previous studies were found to be mostly associated with small vessel disease markers. Our results support findings on the involvement of the cerebellum in cognitive functioning.
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Affiliation(s)
- Sofia Marcolini
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen 9713 GZ, the Netherlands
| | - Jaime D. Mondragón
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen 9713 GZ, the Netherlands
- Universidad Nacional Autónoma de México, Instituto de Neurobiología, Departamento de Neurobiología Conductual y Cognitiva, Laboratorio de Psicofisiología, Querétaro 76230, Mexico
- San Diego State University, Department of Psychology, Life-Span Human Senses Lab, San Diego, California 92182, USA
| | - Esther E. Bron
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam 3015 GD, the Netherlands
| | - Geert J. Biessels
- Department of Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht 3584 CX, the Netherlands
| | - Jurgen A.H.R. Claassen
- Department of Geriatrics, Radboud University Medical Center and Donders Institute, Nijmegen 6525 GD, the Netherlands
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Janne M. Papma
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam 3015 GD, the Netherlands
- Department of Neurology and Alzheimer Center Erasmus MC, Erasmus MC University Medical Center, Rotterdam 3015 GD, the Netherlands
| | - Huub Middelkoop
- Institute of Psychology, Health, Medical and Neuropsychology Unit, Leiden University, Leiden 2316 XC, the Netherlands
- Department of Neurology, Leiden University Medical Centre, Leiden 2333 ZA, the Netherlands
| | - Rudi A.J.O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9713 GZ, the Netherlands
| | - Ronald J.H. Borra
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9713 GZ, the Netherlands
| | - Inez H.G.B. Ramakers
- Alzheimer Center Limburg, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6229 ER, the Netherlands
| | - Wiesje M. van der Flier
- Department of Neurology, Alzheimer Center Amsterdam, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam 1081 HZ, the Netherlands
- Department of Epidemiology & Data Sciences, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam 1117, the Netherlands
| | - Natasha M. Maurits
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen 9713 GZ, the Netherlands
| | - Peter P. De Deyn
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen 9713 GZ, the Netherlands
- Laboratory of Neurochemistry and Behavior, University of Antwerp, Antwerp 2610, Belgium
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