1
|
Zhang B, Hua R, Qing Z, Ni L, Zhang X, Zhao H, Liu R, Lu J, Wu S, Xu Y, Zhu B, Wan S, Sun Y. Abnormal brain functional connectivity coupled with hypoperfusion measured by Resting-State fMRI: An additional contributing factor for cognitive impairment in patients with Alzheimer's disease. Psychiatry Res Neuroimaging 2019; 289:18-25. [PMID: 31125938 DOI: 10.1016/j.pscychresns.2019.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/20/2019] [Accepted: 04/28/2019] [Indexed: 12/11/2022]
Abstract
The contribution of hypoperfusion to abnormal functional connectivity in Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains unclear. In this study, we investigated the potential association between brain perfusion and functional connectivity (FC), and its effects on the cognitive impairment among AD, MCI, and normal controls (NC). One-time acquisition of resting-state functional magnetic resonance imaging (rs-fMRI) was used to study brain perfusion and FC. Compared to the NC, the perfusion in the left temporal lobe showed significantly lower in AD, and bilateral hypoperfusion in the frontal lobe showed in MCI. Using these hypoperfusion areas as seed regions, we found that FC between the left inferior temporal gyrus and medial frontal-cingulate regions in AD patients was significantly lower than that in NCs. The FC between the right medial superior frontal gyrus and left parietal lobe in MCI patients was significantly higher than that in NCs. Additionally, the FC between the right medial superior frontal gyrus and the left superior parietal gyrus were found to be correlated significantly and negatively with mini-mental state examination (MMSE) scores in MCI patients. In conclusion, hypoperfusion may affect cognitive states via abnormal FC as an additional factor contributing to cognitive impairment.
Collapse
Affiliation(s)
- Bing Zhang
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Rui Hua
- The Laboratory for Medical Electronics, School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, China
| | - Zhao Qing
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Ling Ni
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Xin Zhang
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Hui Zhao
- Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Renyuan Liu
- Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Jiaming Lu
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Sichu Wu
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Yun Xu
- Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Bin Zhu
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
| | - Suiren Wan
- The Laboratory for Medical Electronics, School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, China.
| | - Yu Sun
- International Laboratory for Children's Medical Imaging Research, School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, China; Institute of Cancer and Genomic Sciences, University of Birmingham, UK.
| |
Collapse
|
2
|
Minter MR, Taylor JM, Crack PJ. The contribution of neuroinflammation to amyloid toxicity in Alzheimer's disease. J Neurochem 2015; 136:457-74. [PMID: 26509334 DOI: 10.1111/jnc.13411] [Citation(s) in RCA: 279] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/11/2015] [Accepted: 10/22/2015] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease and the most common cause of dementia. Deposition of amyloid-β (Aβ) remains a hallmark feature of the disease, yet the precise mechanism(s) by which this peptide induces neurotoxicity remain unknown. Neuroinflammation has long been implicated in AD pathology, yet its contribution to disease progression is still not understood. Recent evidence suggests that various Aβ complexes interact with microglial and astrocytic expressed pattern recognition receptors that initiate innate immunity. This process involves secretion of pro-inflammatory cytokines, chemokines and generation of reactive oxygen species that, in excess, drive a dysregulated immune response that contributes to neurodegeneration. The mechanisms by which a neuroinflammatory response can influence Aβ production, aggregation and eventual clearance are now becoming key areas where future therapeutic intervention may slow progression of AD. This review will focus on evidence supporting the combined neuroinflammatory-amyloid hypothesis for pathogenesis of AD, describing the key cell types, pathways and mediators involved. Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia worldwide. Deposition of intracellular plaques containing amyloid-beta (Aβ) is a hallmark proteinopathy of the disease yet the precise mechanisms by which this peptide induces neurotoxicity remains unknown. A neuroinflammatory response involving polarized microglial activity, enhanced astrocyte reactivity and elevated pro-inflammatory cytokine and chemokine load has long been implicated in AD and proposed to facilitate neurodegeneration. In this issue we discuss key receptor systems of innate immunity that detect Aβ, drive pro-inflammatory cytokine and chemokine production and influence Aβ aggregation and clearance. Evidence summarized in this review supports the combined neuroinflammatory-amyloid hypothesis for pathogenesis of AD and highlights the potential of immunomodulatory agents as potential future therapies for AD patients.
Collapse
Affiliation(s)
- Myles R Minter
- Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Victoria, Australia
| | - Juliet M Taylor
- Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter J Crack
- Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Victoria, Australia
| |
Collapse
|
3
|
González-Marrero I, Giménez-Llort L, Johanson CE, Carmona-Calero EM, Castañeyra-Ruiz L, Brito-Armas JM, Castañeyra-Perdomo A, Castro-Fuentes R. Choroid plexus dysfunction impairs beta-amyloid clearance in a triple transgenic mouse model of Alzheimer's disease. Front Cell Neurosci 2015; 9:17. [PMID: 25705176 PMCID: PMC4319477 DOI: 10.3389/fncel.2015.00017] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/12/2015] [Indexed: 01/10/2023] Open
Abstract
Compromised secretory function of choroid plexus (CP) and defective cerebrospinal fluid (CSF) production, along with accumulation of beta-amyloid (Aβ) peptides at the blood-CSF barrier (BCSFB), contribute to complications of Alzheimer’s disease (AD). The AD triple transgenic mouse model (3xTg-AD) at 16 month-old mimics critical hallmarks of the human disease: β-amyloid (Aβ) plaques and neurofibrillary tangles (NFT) with a temporal- and regional- specific profile. Currently, little is known about transport and metabolic responses by CP to the disrupted homeostasis of CNS Aβ in AD. This study analyzed the effects of highly-expressed AD-linked human transgenes (APP, PS1 and tau) on lateral ventricle CP function. Confocal imaging and immunohistochemistry revealed an increase only of Aβ42 isoform in epithelial cytosol and in stroma surrounding choroidal capillaries; this buildup may reflect insufficient clearance transport from CSF to blood. Still, there was increased expression, presumably compensatory, of the choroidal Aβ transporters: the low density lipoprotein receptor-related protein 1 (LRP1) and the receptor for advanced glycation end product (RAGE). A thickening of the epithelial basal membrane and greater collagen-IV deposition occurred around capillaries in CP, probably curtailing solute exchanges. Moreover, there was attenuated expression of epithelial aquaporin-1 and transthyretin (TTR) protein compared to Non-Tg mice. Collectively these findings indicate CP dysfunction hypothetically linked to increasing Aβ burden resulting in less efficient ion transport, concurrently with reduced production of CSF (less sink action on brain Aβ) and diminished secretion of TTR (less neuroprotection against cortical Aβ toxicity). The putative effects of a disabled CP-CSF system on CNS functions are discussed in the context of AD.
Collapse
Affiliation(s)
| | - Lydia Giménez-Llort
- Institute of Neurosciences and Department of Psychiatry and Forensic Medicine, Autonomous University of Barcelona Barcelona, Spain
| | - Conrad E Johanson
- Department of Neurosurgery, Alpert Medical School at Brown University Providence, Rhode Island, USA
| | | | | | | | | | - Rafael Castro-Fuentes
- Department of Physiology, School of Medicine, University of La Laguna Tenerife, Spain
| |
Collapse
|
4
|
Avila-Muñoz E, Arias C. When astrocytes become harmful: functional and inflammatory responses that contribute to Alzheimer's disease. Ageing Res Rev 2014; 18:29-40. [PMID: 25078115 DOI: 10.1016/j.arr.2014.07.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/03/2014] [Accepted: 07/21/2014] [Indexed: 12/24/2022]
Abstract
A growing body of research suggests that astrocytes play roles as contributors to the pathophysiology of Alzheimer's disease (AD). Several lines of evidence propose that activated astrocytes produce and release proinflammatory molecules that may be critical for the generation of amyloid-β peptide (Aβ). However, accumulating evidence indicates that Aβ may activate astrocytes, which leads to an increase in cytokines that has been suggested to be a causative factor in the cognitive dysfunction of AD; thus, a vicious circle may be created. Intrinsic inflammatory mechanisms may provide a regulatory system that is capable of influencing the neuronal microenvironment that affects neuronal survival. In this article, we address the evidence surrounding the interactions of dysfunctional astrocytes with neighboring neurons that may initiate a cascade of events that culminates with neuronal injury and the expression of the hallmark lesions of AD. Comprehensive knowledge of the molecular mechanisms underlying the participation of astrocytes in neurodegeneration could aid the development of therapies to restore proper astrocyte function that can be used in AD patients to prevent or alleviate the progression of the disease in a more efficient and comprehensive manner.
Collapse
|
5
|
Chen SM, Fan CC, Chiue MS, Chou C, Chen JH, Hseu RS. Hemodynamic and neuropathological analysis in rats with aluminum trichloride-induced Alzheimer's disease. PLoS One 2013; 8:e82561. [PMID: 24376545 PMCID: PMC3869709 DOI: 10.1371/journal.pone.0082561] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 10/25/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND AIMS Hemodynamic normality is crucial to maintaining the integrity of cerebral vessels and, therefore, preserving the cognitive functions of Alzheimer's disease patients. This study investigates the implications of the hemodynamic changes and the neuropathological diversifications of AlCl3-induced AD. METHODS The experimental animals were 8- to 12-wk-old male Wistar rats. The rats were randomly divided into 2 groups: a control group and a (+)control group. Food intake, water intake, and weight changes were recorded daily for 22 wk. Synchronously, the regional cerebral blood flow (rCBF) of the rats with AlCl3-induced AD were measured using magnetic resonance imaging (MRI). The hemorheological parameters were analyzed using a computerized auto-rotational rheometer. The brain tissue of the subjects was analyzed using immunohistological chemical (IHC) staining to determine the beta-amyloid (Aβ) levels. RESULTS The results of hemodynamic analysis revealed that the whole blood viscosity (WBV), fibrinogen, plasma viscosity and RBC aggregation index (RAI) in (+)control were significantly higher than that of control group, while erythrocyte electrophoresis (EI) of whole blood in (+)control were significantly lower than that of control group. The results of acetylcholinesterase-RBC (AChE-RBC)in the (+)control group was significantly higher than that of the control group. The results also show that the reduction of rCBF in rats with AlCl3-induced AD was approximately 50% to 60% that of normal rats. IHC stain results show that significantly more Aβ plaques accumulated in the hippocampus and cortex of the (+)control than in the control group. CONCLUSION The results accentuate the importance of hemorheology and reinforce the specific association between hemodynamic and neuropathological changes in rats with AlCl3-induced AD. Hemorheological parameters, such as WBV and fibrinogen, and AChE-RBC were ultimately proven to be useful biomarkers of the severity and progression of AD patients. In addition, the parameters can be substituted for invasive inspection in therapeutic intervention.
Collapse
Affiliation(s)
- Szu-Ming Chen
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
- Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsinchu, Taiwan
| | - Chi-Chen Fan
- Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsinchu, Taiwan
- Department of Physiology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Ming-Shiuan Chiue
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering and Molecular Imaging Center, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chi Chou
- Department of Physiology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Jyh-Horng Chen
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering and Molecular Imaging Center, National Taiwan University, Taipei, Taiwan
| | - Ruey-Shyang Hseu
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| |
Collapse
|