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Nuñez-Diaz C, Andersson E, Schultz N, Pocevičiūtė D, Hansson O, Nilsson KPR, Wennström M. The fluorescent ligand bTVBT2 reveals increased p-tau uptake by retinal microglia in Alzheimer's disease patients and App NL-F/NL-F mice. Alzheimers Res Ther 2024; 16:4. [PMID: 38167557 PMCID: PMC10763304 DOI: 10.1186/s13195-023-01375-7] [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: 07/16/2023] [Accepted: 12/24/2023] [Indexed: 01/05/2024]
Abstract
BACKGROUND Amyloid beta (Aβ) deposits and hyperphosphorylated tau (p-tau) accumulation have been identified in the retina of Alzheimer's disease (AD) patients and transgenic AD mice. Previous studies have shown that retinal microglia engulf Aβ, but this property decreases in AD patients. Whether retinal microglia also take up p-tau and if this event is affected in AD is yet not described. In the current study, we use the p-tau-specific thiophene-based ligand bTVBT2 to investigate the relationship between disease progression and p-tau uptake by microglia in the retina of AD patients and AppNL-F/NL-F knock-in mice, an AD mouse model known to demonstrate extracellular Aβ plaques and dystrophic neurites in the brain from 6 months of age. METHODS Evaluation of bTVBT2 specificity and its presence within microglia was assessed by immunofluorescent staining of hippocampal sections and flat-mount retina samples from non-demented controls, AD patients, 3-, 9-, and 12-month-old AppNL-F/NL-F knock-in mice and 12- and 18-month-old wild type (WT) mice. We used ImageJ to analyze the amount of bTVBT2 inside Iba1-positive microglia. Co-localization between the ligand and p-tau variant Ser396/Ser404 (PHF-1), Aβ, phosphorylated TAR DNA binding protein 43 (pTDP-43), and islet amyloid polypeptide (IAPP) in the brain and retina was analyzed using confocal imaging. RESULTS Confocal imaging analysis showed that bTVBT2 binds to PHF-1- and AT8-positive aggregates inside retinal microglia, and not to Aβ, pTDP-43, or IAPP. The density of bTVBT2-positive microglia was higher in cases with a high Aβ load compared to those with a low Aβ load. This density correlated with the neurofibrillary tangle load in the brain, but not with retinal levels of high molecular weight (aggregated) Aβ40 or Aβ42. Analysis of AppNL-F/NL-F knock-in mouse retina further showed that 50% of microglia in 3-month-old AppNL-F/NL-F knock-in mice contained bTVBT2. The percentage significantly increased in 9- and 12-month-old mice. CONCLUSION Our study suggests that the microglial capability to uptake p-tau in the retina persists and intensifies with AD progression. These results also highlight bTVBT2 as a ligand of interest in future monitoring of retinal AD pathology.
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Affiliation(s)
- Cristina Nuñez-Diaz
- Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Emelie Andersson
- Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Nina Schultz
- Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
- Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Dovilė Pocevičiūtė
- Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Oskar Hansson
- Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
- Memory Clinic, Skåne University Hospital, Malmö, Sweden
| | - K Peter R Nilsson
- Department of Physics, Chemistry and Biology IFM, Linköping University, 581 83, Linköping, Sweden
| | - Malin Wennström
- Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
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Shen L, Tang X, Zhang H, Zhuang H, Lin J, Zhao Y, Liu X. Targeted Metabolomic Analysis of the Eye Tissue of Triple Transgenic Alzheimer's Disease Mice at an Early Pathological Stage. Mol Neurobiol 2023; 60:7309-7328. [PMID: 37553545 DOI: 10.1007/s12035-023-03533-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 07/22/2023] [Indexed: 08/10/2023]
Abstract
Alzheimer's disease (AD) is a severe neurodegenerative disease in older people. Despite some consensus on pathogenesis of AD established by previous researches, further elucidation is still required for better understanding. This study analyzed the eye tissues of 2- and 6-month-old triple transgenic AD (3 × Tg-AD) male mice and age-sex-matched wild-type (WT) mice using a targeted metabolomics approach. Compared with WT mice, 20 and 44 differential metabolites were identified in 2- and 6-month-old AD mice, respectively. They were associated with purine metabolism, pantothenate and CoA biosynthesis, pyruvate metabolism, lysine degradation, glycolysis/gluconeogenesis, and pyrimidine metabolism pathways. Among them, 8 metabolites presented differences in both the two groups, and 5 of them showed constant trend of change. The results indicated that the eye tissues of 3 × Tg-AD mice underwent changes in the early stages of the disease, with changes in metabolites observed at 2 months of age and more pronounced at 6 months of age, which is consistent with our previous studies on hippocampal targeted metabolomics in 3 × Tg-AD mice. Therefore, a joint analysis of data from this study and previous hippocampal study was performed, and the differential metabolites and their associated mechanisms were similar in eye and hippocampal tissues, but with tissue specificity.
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Affiliation(s)
- Liming Shen
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
- Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, 518055, People's Republic of China
- Shenzhen Key Laboratory of Marine, Biotechnology, and Ecology, Shenzhen, People's Republic of China
| | - Xiaoxiao Tang
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
| | - Huajie Zhang
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
| | - Hongbin Zhuang
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
| | - Jing Lin
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
| | - Yuxi Zhao
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China
| | - Xukun Liu
- College of Life Science and Oceanography, Shenzhen University, Xueyuan Ave 1688, Shenzhen, 518060, People's Republic of China.
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Wang S, Jiang X, Peng W, Yang S, Pi R, Zhou S. Acrolein Induces Retinal Abnormalities of Alzheimer's Disease in Mice. Int J Mol Sci 2023; 24:13576. [PMID: 37686379 PMCID: PMC10487815 DOI: 10.3390/ijms241713576] [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: 07/18/2023] [Revised: 08/12/2023] [Accepted: 08/17/2023] [Indexed: 09/10/2023] Open
Abstract
It is reported that retinal abnormities are related to Alzheimer's disease (AD) in patients and animal models. However, it is unclear whether the retinal abnormities appear in the mouse model of sporadic Alzheimer's disease (sAD) induced by acrolein. We investigated the alterations of retinal function and structure, the levels of β-amyloid (Aβ) and phosphorylated Tau (p-Tau) in the retina, and the changes in the retinal vascular system in this mouse model. We demonstrated that the levels of Aβ and p-Tau were increased in the retinas of mice from the acrolein groups. Subsequently, a decreased amplitudes of b-waves in the scotopic and photopic electroretinogram (ERG), decreased thicknesses of the retinal nerve fiber layer (RNFL) in the retina, and slight retinal venous beading were found in the mice induced by acrolein. We propose that sAD mice induced by acrolein showed abnormalities in the retina, which may provide a valuable reference for the study of the retina in sAD.
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Affiliation(s)
- Shuyi Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Xiuying Jiang
- Department of Ophthalmology, Affiliated Foshan Hospital, Southern Medical University, Foshan 528000, China
| | - Weijia Peng
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Shuangjian Yang
- Guangdong Provincial Institute for Vision and Eye Research, Guangzhou 510060, China
| | - Rongbiao Pi
- School of Medicine, Sun Yat-sen University, Shenzhen 528406, China
| | - Shiyou Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
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Fernández-Albarral JA, Salobrar-García E, Matamoros JA, Fernández-Mendívil C, del Sastre E, Chen L, de Hoz R, López-Cuenca I, Sánchez-Puebla L, Ramírez JM, Salazar JJ, Lopez MG, Ramírez AI. Microglial Hemoxygenase-1 Deletion Reduces Inflammation in the Retina of Old Mice with Tauopathy. Antioxidants (Basel) 2022; 11:2151. [PMID: 36358522 PMCID: PMC9686584 DOI: 10.3390/antiox11112151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 10/27/2022] [Accepted: 10/27/2022] [Indexed: 09/26/2023] Open
Abstract
Tauopathies such as Alzheimer's disease are characterized by the accumulation of neurotoxic aggregates of tau protein. With aging and, especially, in Alzheimer's patients, the inducible enzyme heme oxygenase 1 (HO-1) progressively increases in microglia, causing iron accumulation, neuroinflammation, and neurodegeneration. The retina is an organ that can be readily accessed and can reflect changes that occur in the brain. In this context, we evaluated how the lack of microglial HO-1, using mice that do not express HO-1 in microglia (HMO-KO), impacts retinal macro and microgliosis of aged subjects (18 months old mice) subjected to tauopathy by intrahippocampal delivery of AAV-hTauP301L (TAU). Our results show that although tauopathy, measured as anti-TAUY9 and anti-AT8 positive immunostaining, was not observed in the retina of WT-TAU or HMO-KO+TAU mice, a morphometric study of retinal microglia and macroglia showed significant retinal changes in the TAU group compared to the WT group, such as: (i) increased number of activated microglia, (ii) retraction of microglial processes, (iii) increased number of CD68+ microglia, and (iv) increased retinal area occupied by GFAP (AROA) and C3 (AROC3). This retinal inflammatory profile was reduced in HMO-KO+TAU mice. Conclusion: Reduction of microglial HO-1 could be beneficial to prevent tauopathy-induced neuroinflammation.
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Affiliation(s)
- José A. Fernández-Albarral
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Elena Salobrar-García
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - José A. Matamoros
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Cristina Fernández-Mendívil
- Instituto Teófilo Hernando for Drug Discovery, Department of Pharmacology, School of Medicine, Universidad Autónoma Madrid, 28029 Madrid, Spain
- Instituto de Investigación Sanitario (IIS-IP), Hospital Universitario de La Princesa, 28006 Madrid, Spain
| | - Eric del Sastre
- Instituto Teófilo Hernando for Drug Discovery, Department of Pharmacology, School of Medicine, Universidad Autónoma Madrid, 28029 Madrid, Spain
- Instituto de Investigación Sanitario (IIS-IP), Hospital Universitario de La Princesa, 28006 Madrid, Spain
| | - Lejing Chen
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Rosa de Hoz
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Inés López-Cuenca
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Lidia Sánchez-Puebla
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - José M. Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Medicina, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Juan J. Salazar
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Manuela G. Lopez
- Instituto Teófilo Hernando for Drug Discovery, Department of Pharmacology, School of Medicine, Universidad Autónoma Madrid, 28029 Madrid, Spain
- Instituto de Investigación Sanitario (IIS-IP), Hospital Universitario de La Princesa, 28006 Madrid, Spain
| | - Ana I. Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Grupo UCM 920105, IdISSC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, 28037 Madrid, Spain
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Hydrogen Sulfide Attenuates Neuroinflammation by Inhibiting the NLRP3/Caspase-1/GSDMD Pathway in Retina or Brain Neuron following Rat Ischemia/Reperfusion. Brain Sci 2022; 12:brainsci12091245. [PMID: 36138981 PMCID: PMC9497235 DOI: 10.3390/brainsci12091245] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/30/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Gasdermin D-executing pyroptosis mediated by NLRP3 inflammasomes has been recognized as a key pathogenesis during stroke. Hydrogen sulfide (H2S) could protect CNS against ischemia/reperfusion (I/R)-induced neuroinflammation, while the underlying mechanism remains unclear. The study applied the middle cerebral artery occlusion/reperfusion (MCAO/R) model to investigate how the brain and the retinal injuries were alleviated in sodium hydrogen sulfide (NaHS)-treated rats. The rats were assigned to four groups and received an intraperitoneal injection of 50 μmol/kg NaHS or NaCl 15 min after surgery. Neurological deficits were evaluated using the modified neurologic severity score. The quantification of pro-inflammatory cytokines, NLRP3, caspase-1, and GSDMD were determined by ELISA and Western blot. Cortical and retinal neurodegeneration and cell pyroptosis were determined by histopathologic examination. Results showed that NaHS rescued post-stroke neurological deficits and infarct progression, improved retina injury, and attenuated neuroinflammation in the brain cortexes and the retinae. NaHS administration inhibits inflammation by blocking the NLRP3/caspase-1/GSDMD pathway and further suppressing neuronal pyroptosis. This is supported by the fact that it reversed the high-level of NLRP3, caspase-1, and GSDMD following I/R. Our findings suggest that compounds with the ability to donate H2S could constitute a novel therapeutic strategy for ischemic stroke.
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Ferreira H, Serranho P, Guimarães P, Trindade R, Martins J, Moreira PI, Ambrósio AF, Castelo-Branco M, Bernardes R. Stage-independent biomarkers for Alzheimer's disease from the living retina: an animal study. Sci Rep 2022; 12:13667. [PMID: 35953633 PMCID: PMC9372147 DOI: 10.1038/s41598-022-18113-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 08/05/2022] [Indexed: 12/02/2022] Open
Abstract
The early diagnosis of neurodegenerative disorders is still an open issue despite the many efforts to address this problem. In particular, Alzheimer’s disease (AD) remains undiagnosed for over a decade before the first symptoms. Optical coherence tomography (OCT) is now common and widely available and has been used to image the retina of AD patients and healthy controls to search for biomarkers of neurodegeneration. However, early diagnosis tools would need to rely on images of patients in early AD stages, which are not available due to late diagnosis. To shed light on how to overcome this obstacle, we resort to 57 wild-type mice and 57 triple-transgenic mouse model of AD to train a network with mice aged 3, 4, and 8 months and classify mice at the ages of 1, 2, and 12 months. To this end, we computed fundus images from OCT data and trained a convolution neural network (CNN) to classify those into the wild-type or transgenic group. CNN performance accuracy ranged from 80 to 88% for mice out of the training group’s age, raising the possibility of diagnosing AD before the first symptoms through the non-invasive imaging of the retina.
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Affiliation(s)
- Hugo Ferreira
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - Pedro Serranho
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Department of Sciences and Technology, Universidade Aberta, Rua da Escola Politécnica, n.º 147, 1269-001, Lisboa, Portugal
| | - Pedro Guimarães
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - Rita Trindade
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - João Martins
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Clinical Academic Center of Coimbra (CACC), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - Paula I Moreira
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Clinical Academic Center of Coimbra (CACC), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Laboratory of Physiology, Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - António Francisco Ambrósio
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Clinical Academic Center of Coimbra (CACC), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - Miguel Castelo-Branco
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.,Clinical Academic Center of Coimbra (CACC), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - Rui Bernardes
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal. .,Clinical Academic Center of Coimbra (CACC), Faculty of Medicine (FMUC), University of Coimbra, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.
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Frame G, Schuller A, Smith MA, Crish SD, Dengler-Crish CM. Alterations in Retinal Signaling Across Age and Sex in 3xTg Alzheimer’s Disease Mice. J Alzheimers Dis 2022; 88:471-492. [PMID: 35599482 PMCID: PMC9398084 DOI: 10.3233/jad-220016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Background: Visual disturbances often precede cognitive dysfunction in patients with Alzheimer’s disease (AD) and may coincide with early accumulation of amyloid-β (Aβ) protein in the retina. These findings have inspired critical research on in vivo ophthalmic Aβ imaging for disease biomarker detection but have not fully answered mechanistic questions on how retinal pathology affects visual signaling between the eye and brain. Objective: The goal of this study was to provide a functional and structural assessment of eye-brain communication between retinal ganglion cells (RGCs) and their primary projection target, the superior colliculus, in female and male 3xTg-AD mice across disease stages. Methods: Retinal electrophysiology, axonal transport, and immunofluorescence were used to determine RGC projection integrity, and retinal and collicular Aβ levels were assessed with advanced protein quantitation techniques. Results: 3xTg mice exhibited nuanced deficits in RGC electrical signaling, axonal transport, and synaptic integrity that exceeded normal age-related decrements in RGC function in age- and sex-matched healthy control mice. These deficits presented in sex-specific patterns among 3xTg mice, differing in the timing and severity of changes. Conclusion: These data support the premise that retinal Aβ is not just a benign biomarker in the eye, but may contribute to subtle, nuanced visual processing deficits. Such disruptions might enhance the biomarker potential of ocular amyloid and differentiate patients with incipient AD from patients experiencing normal age-related decrements in visual function.
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Affiliation(s)
- Gabrielle Frame
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
- Biomedical Sciences Graduate Program, Kent State University, Kent, OH, USA
| | - Adam Schuller
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Matthew A. Smith
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
- Rebecca D. Considine Research Institute, Akron Children’s Hospital, Akron, OH, USA
| | - Samuel D. Crish
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
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Alzheimer's Disease Seen through the Eye: Ocular Alterations and Neurodegeneration. Int J Mol Sci 2022; 23:ijms23052486. [PMID: 35269629 PMCID: PMC8910735 DOI: 10.3390/ijms23052486] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 12/18/2022] Open
Abstract
Alzheimer’s Disease (AD) is one of the main neurodegenerative diseases worldwide. Unfortunately, AD shares many similarities with other dementias at early stages, which impedes an accurate premortem diagnosis. Therefore, it is urgent to find biomarkers to allow for early diagnosis of the disease. There is increasing scientific evidence highlighting the similarities between the eye and other structures of the CNS, suggesting that knowledge acquired in eye research could be useful for research and diagnosis of AD. For example, the retina and optic nerve are considered part of the central nervous system, and their damage can result in retrograde and anterograde axon degeneration, as well as abnormal protein aggregation. In the anterior eye segment, the aqueous humor and tear film may be comparable to the cerebrospinal fluid. Both fluids are enriched with molecules that can be potential neurodegenerative biomarkers. Indeed, the pathophysiology of AD, characterized by cerebral deposits of amyloid-beta (Aβ) and tau protein, is also present in the eyes of AD patients, besides numerous structural and functional changes observed in the structure of the eyes. Therefore, all this evidence suggests that ocular changes have the potential to be used as either predictive values for AD assessment or as diagnostic tools.
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Czapski GA, Strosznajder JB. Glutamate and GABA in Microglia-Neuron Cross-Talk in Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222111677. [PMID: 34769106 PMCID: PMC8584169 DOI: 10.3390/ijms222111677] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 12/18/2022] Open
Abstract
The physiological balance between excitation and inhibition in the brain is significantly affected in Alzheimer’s disease (AD). Several neuroactive compounds and their signaling pathways through various types of receptors are crucial in brain homeostasis, among them glutamate and γ-aminobutyric acid (GABA). Activation of microglial receptors regulates the immunological response of these cells, which in AD could be neuroprotective or neurotoxic. The novel research approaches revealed the complexity of microglial function, including the interplay with other cells during neuroinflammation and in the AD brain. The purpose of this review is to describe the role of several proteins and multiple receptors on microglia and neurons, and their involvement in a communication network between cells that could lead to different metabolic loops and cell death/survival. Our review is focused on the role of glutamatergic, GABAergic signaling in microglia–neuronal cross-talk in AD and neuroinflammation. Moreover, the significance of AD-related neurotoxic proteins in glutamate/GABA-mediated dialogue between microglia and neurons was analyzed in search of novel targets in neuroprotection, and advanced pharmacological approaches.
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