scholarly journals Potential caveats of putative microglia-specific markers for assessment of age-related cerebrovascular neuroinflammation

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Pedram Honarpisheh ◽  
Juneyoung Lee ◽  
Anik Banerjee ◽  
Maria P. Blasco-Conesa ◽  
Parisa Honarpisheh ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Ex Vivo ◽  
Myeloid Cells ◽  
Amyloid Angiopathy ◽  
Future Studies ◽  
Age Related ◽  
In Vivo Animal Models ◽  
Intermediate Expression ◽  
The Brain

Abstract Background The ability to distinguish resident microglia from infiltrating myeloid cells by flow cytometry-based surface phenotyping is an important technique for examining age-related neuroinflammation. The most commonly used surface markers for the identification of microglia include CD45 (low-intermediate expression), CD11b, Tmem119, and P2RY12. Methods In this study, we examined changes in expression levels of these putative microglia markers in in vivo animal models of stroke, cerebral amyloid angiopathy (CAA), and aging as well as in an ex vivo LPS-induced inflammation model. Results We demonstrate that Tmem119 and P2RY12 expression is evident within both CD45int and CD45high myeloid populations in models of stroke, CAA, and aging. Interestingly, LPS stimulation of FACS-sorted adult microglia suggested that these brain-resident myeloid cells can upregulate CD45 and downregulate Tmem119 and P2RY12, making them indistinguishable from peripherally derived myeloid populations. Importantly, our findings show that these changes in the molecular signatures of microglia can occur without a contribution from the other brain-resident or peripherally sourced immune cells. Conclusion We recommend future studies approach microglia identification by flow cytometry with caution, particularly in the absence of the use of a combination of markers validated for the specific neuroinflammation model of interest. The subpopulation of resident microglia residing within the “infiltrating myeloid” population, albeit small, may be functionally important in maintaining immune vigilance in the brain thus should not be overlooked in neuroimmunological studies.

Antibodies to β-Amyloid Decrease the Blood-to-Brain Transfer of β-Amyloid Peptide1

2002 ◽  
Vol 227 (8) ◽  
pp. 609-615 ◽  
Author(s):  
Weihong Pan ◽  
Beka Solomon ◽  
Lawrence M. Maness ◽  
Abba J. Kastin
Keyword(s):  
Ex Vivo ◽  
Amyloid Β ◽  
Brain Perfusion ◽  
Brain Parenchyma ◽  
Amyloid Angiopathy ◽  
Β Amyloid ◽  
Blocking Antibodies ◽  
The Brain

Amyloid-β peptides (Aβ) play an important role in the pathophysiology of dementia of the Alzheimer's type and in amyloid angiopathy. Aβ outside the CNS could contribute to plaque formation in the brain where its entry would involve interactions with the blood-brain barrier (BBB). Effective antibodies to Aβ have been developed in an effort to vaccinate against Alzheimer's disease. These antibodies could interact with Aβ in the peripheral blood, block the passage of Aβ across the BBB, or prevent Aβ deposition within the CNS. To determine whether the blocking antibodies act at the BBB level, we examined the influx of radiolabeled Aβ (125I-Aβ1-40) into the brain after ex-vivo incubation with the antibodies. Antibody mAb3D6 (élan Company) reduced the blood-to-brain influx of Aβ after iv bolus injection. It also significantly decreased the accumulation of Aβ in brain parenchyma. To confirm the in-vivo study and examine the specificity of mAb3D6, in-situ brain perfusion in serum-free buffer was performed after incubation of 125I-Aβ1-40 with another antibody mAbmc1 (DAKO Company). The presence of mAbmc1 also caused significant reduction of the influx of Aβ into the brain after perfusion. Therefore, effective antibodies to Aβ can reduce the influx of Aβ1-40 into the brain.

Drusen in the Peripheral Retina of the Alzheimer’s Eye

2018 ◽  
Vol 15 (8) ◽  
pp. 743-750 ◽  
Author(s):  
Kresimir Ukalovic ◽  
Sijia Cao ◽  
Sieun Lee ◽  
Qiaoyue Tang ◽  
Mirza Faisal Beg ◽  
...  
Keyword(s):  
Peripheral Retina ◽  
Amyloid Angiopathy ◽  
Temporal Region ◽  
Future Studies ◽  
Eye Tissues ◽  
Neuropathological Diagnosis ◽  
Ocular Imaging ◽  
Cerebral Amyloid ◽  
The Brain ◽  
Oil Red O

Background: Recent work on Alzheimer's disease (AD) diagnosis focuses on neuroimaging modalities; however, these methods are expensive, invasive, and not available to all patients. Ocular imaging of biomarkers, such as drusen in the peripheral retina, could provide an alternative method to diagnose AD. Objective: This study compares macular and peripheral drusen load in control and AD eyes. Methods: Postmortem eye tissues were obtained from donors with a neuropathological diagnosis of AD. Retina from normal donors were processed and categorized into younger (<55 years) and older (>55 years) groups. After fixation and dissection, 3-6 mm punches of RPE/choroid were taken in macular and peripheral (temporal, superior, and inferior) retinal regions. Oil red O positive drusen were counted and grouped into two size categories: small (<63 μm) and intermediate (63-125 μm). Results: There was a significant increase in the total number of macular and peripheral hard drusen in older, compared to younger, normal eyes (p<0.05). Intermediate hard drusen were more commonly found in the temporal region of AD eyes compared to older normal eyes, even after controlling for age (p<0.05). Among the brain and eye tissues from AD donors, there was a significant relationship between cerebral amyloid angiopathy (CAA) severity and number of temporal intermediate hard drusen (r=0.78, p<0.05). Conclusion: Imaging temporal drusen in the eye may have benefit for diagnosing and monitoring progression of AD. Our results on CAA severity and temporal intermediate drusen in the AD eye are novel. Future studies are needed to further understand the interactions among CAA and drusen formation.

Influence of estrogen on individual exercise motivation and bone protection in ovariectomized rats

2018 ◽  
Vol 52 (5) ◽  
pp. 479-489 ◽  
Author(s):  
Sebastian T Müller ◽  
Annekathrin M Keiler ◽  
Kristin Kräker ◽  
Oliver Zierau ◽  
Ricardo Bernhardt
Keyword(s):  
Bone Loss ◽  
Ex Vivo ◽  
Voluntary Exercise ◽  
Ovariectomized Rats ◽  
Protective Effects ◽  
Exercise Motivation ◽  
Running Wheel ◽  
Future Studies ◽  
Bone Protection

Bone protection and metabolism are directly linked to estrogen levels, but exercise is also considered to have bone protective effects. Reduced estrogen levels lead to a variety of disorders, for example, bone loss and reduced movement drive. The objective of this study was to investigate the effects of estrogen on individual voluntary exercise motivation and bone protection. We investigated sham operated, ovariectomized, and ovariectomized with estrogen supplemented Wistar rats (20 weeks old) either with or without access to exercise wheels. We selected an experimental approach where we could monitor the individual exercise of group-housed rats with ad libitum access to a running wheel with the help of a subcutaneous chip. In vivo and ex vivo microcomputed tomography analyses of the tibia were performed at two-week intervals from week 0 to week 6. Furthermore, tibial trabecular structure was evaluated based on histomorphometric analyses. We observed a significant bone protective effect of E2. For exercise performance, a substantially high intra-group variability was observed, especially in the E2 group. We presume that dominant behavior occurs within the group-housed rats resulting in a hierarchical access to the running wheel and a high variability of distance run. Exercise did not prevent ovariectomy-induced bone loss. However, lack of estrogen within the ovariectomized rats led to a drastically reduced activity prevented by estrogen supplementation. Our findings are important for future studies working with group-housed rats and exercise. The reason for the high intra-group variability in exercise needs to be investigated in future studies.

scholarly journals A method for single-neuron chronic recording from the retina in awake mice

Science ◽  
2018 ◽  
Vol 360 (6396) ◽  
pp. 1447-1451 ◽  
Author(s):  
Guosong Hong ◽  
Tian-Ming Fu ◽  
Mu Qiao ◽  
Robert D. Viveros ◽  
Xiao Yang ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Single Neuron ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Retinal Ganglion ◽  
Chronic Recording ◽  
The Brain

The retina, which processes visual information and sends it to the brain, is an excellent model for studying neural circuitry. It has been probed extensively ex vivo but has been refractory to chronic in vivo electrophysiology. We report a nonsurgical method to achieve chronically stable in vivo recordings from single retinal ganglion cells (RGCs) in awake mice. We developed a noncoaxial intravitreal injection scheme in which injected mesh electronics unrolls inside the eye and conformally coats the highly curved retina without compromising normal eye functions. The method allows 16-channel recordings from multiple types of RGCs with stable responses to visual stimuli for at least 2 weeks, and reveals circadian rhythms in RGC responses over multiple day/night cycles.

Ex Vivo Brain Preparation to Analyze Vocal Pathways of Xenopus Frogs

2021 ◽  
Vol 2021 (9) ◽  
pp. pdb.prot106872
Author(s):  
Ayako Yamaguchi
Keyword(s):  
Neural Activity ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Neural Basis ◽  
Vocal Production ◽  
Basic Principles ◽  
Electrophysiological Recordings ◽  
The Brain

Understanding the neural basis of behavior is a challenging task for technical reasons. Most methods of recording neural activity require animals to be immobilized, but neural activity associated with most behavior cannot be recorded from an anesthetized, immobilized animal. Using amphibians, however, there has been some success in developing in vitro brain preparations that can be used for electrophysiological and anatomical studies. Here, we describe an ex vivo frog brain preparation from which fictive vocalizations (the neural activity that would have produced vocalizations had the brain been attached to the muscle) can be elicited repeatedly. When serotonin is applied to the isolated brains of male and female African clawed frogs, Xenopus laevis, laryngeal nerve activity that is a facsimile of those that underlie sex-specific vocalizations in vivo can be readily recorded. Recently, this preparation was successfully used in other species within the genus including Xenopus tropicalis and Xenopus victorianus. This preparation allows a variety of techniques to be applied including extracellular and intracellular electrophysiological recordings and calcium imaging during vocal production, surgical and pharmacological manipulation of neurons to evaluate their impact on motor output, and tract tracing of the neural circuitry. Thus, the preparation is a powerful tool with which to understand the basic principles that govern the production of coherent and robust motor programs in vertebrates.

Ageing and the human brain

2020 ◽  
pp. 170-182
Author(s):  
Verena Heise ◽  
Enikő Zsoldos ◽  
Klaus P. Ebmeier
Keyword(s):  
In Vivo Imaging ◽  
Allostatic Load ◽  
Public Health Medicine ◽  
Causal Factors ◽  
Stress Markers ◽  
Age Related ◽  
Brain Changes ◽  
Heuristic Device ◽  
The Brain

There is little doubt that the brain changes with time, and all research in psychiatry is predicated on holding age constant in comparing groups of patients or estimating the effect sizes of causal factors. Nevertheless, relatively little is known about the mechanisms that are responsible for translating time into ageing. This chapter tries, after an overview of the principal mechanisms involved in biological ageing, to summarize the age-related changes observable in brains in vivo and to demonstrate the types of investigations that may cast light on such mechanisms in the future. A useful heuristic device to order the multiple potential causes of ageing is the chronic stress–allostatic load model, widely employed in epidemiology, public health medicine, and health psychology. In vivo imaging provides a method to test the translation of intermediate stress markers, such as vascular risk, metabolic syndrome, or allostatic load, into predictors of age-related brain changes.

Aptamers against mouse and human tumor-infiltrating myeloid cells as reagents for targeted chemotherapy

2020 ◽  
Vol 12 (548) ◽  
pp. eaav9760
Author(s):  
Adriana De La Fuente ◽  
Serena Zilio ◽  
Jimmy Caroli ◽  
Dimitri Van Simaeys ◽  
Emilia M. C. Mazza ◽  
...  
Keyword(s):  
Mouse Models ◽  
Anticancer Agents ◽  
Targeted Delivery ◽  
Tumor Regression ◽  
Ex Vivo ◽  
Myeloid Cells ◽  
Human Tumor ◽  
Rna Aptamers ◽  
Targeted Chemotherapy

Local delivery of anticancer agents has the potential to maximize treatment efficacy and minimize the acute and long-term systemic toxicities. Here, we used unsupervised systematic evolution of ligands by exponential enrichment to identify four RNA aptamers that specifically recognized mouse and human myeloid cells infiltrating tumors but not their peripheral or circulating counterparts in multiple mouse models and from patients with head and neck squamous cell carcinoma (HNSCC). The use of these aptamers conjugated to doxorubicin enhanced the accumulation and bystander release of the chemotherapeutic drug in both primary and metastatic tumor sites in breast and fibrosarcoma mouse models. In the 4T1 mammary carcinoma model, these doxorubicin-conjugated aptamers outperformed Doxil, the first clinically approved highly optimized nanoparticle for targeted chemotherapy, promoting tumor regression after just three administrations with no detected changes in weight loss or blood chemistry. These RNA aptamers recognized tumor infiltrating myeloid cells in a variety of mouse tumors in vivo and from human HNSCC ex vivo. This work suggests the use of RNA aptamers for the detection of myeloid-derived suppressor cells in humans and for a targeted delivery of chemotherapy to the tumor microenvironment in multiple malignancies.

scholarly journals Development and Optimization of a Fluorescent Imaging System to Detect Amyloid-β Proteins: Phantom Study

2018 ◽  
Vol 9 ◽  
pp. 117959721878108 ◽  
Author(s):  
David Tes ◽  
Karl Kratkiewicz ◽  
Ahmed Aber ◽  
Luke Horton ◽  
Mohsin Zafar ◽  
...  
Keyword(s):  
Alzheimer Disease ◽  
Imaging System ◽  
Ex Vivo ◽  
Amyloid Β ◽  
The United States ◽  
Fluorescent Imaging ◽  
Fluorescent Properties ◽  
In Vivo Experiments ◽  
The Brain

Alzheimer disease is the most common form of dementia, affecting more than 5 million people in the United States. During the progression of Alzheimer disease, a particular protein begins to accumulate in the brain and also in extensions of the brain, ie, the retina. This protein, amyloid-β (Aβ), exhibits fluorescent properties. The purpose of this research article is to explore the implications of designing a fluorescent imaging system able to detect Aβ proteins in the retina. We designed and implemented a fluorescent imaging system with a range of applications that can be reconfigured on a fluorophore to fluorophore basis and tested its feasibility and capabilities using Cy5 and CRANAD-2 imaging probes. The results indicate a promising potential for the imaging system to be used to study the Aβ biomarker. A performance evaluation involving ex vivo and in vivo experiments is planned for future study.

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