Name: quantitative 3d in silico modeling (q3dism) of cerebral amyloid-beta phagocytosis in rodent models of alzheimer's disease
Uploaded: 2016-12-26T13:00:00.000+00:00
Duration: 9 min 33 s
Description: Watch this Scientific Journal Video about Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease at JoVE.com

M-V.G-S. is supported by a BrightFocus Foundation Alzheimer's Disease Research Fellowship Award (A2015309F) and an Alzheimer's Association, California Southland Chapter Young Investigator Award. T.M.W. is supported by an ARCS Foundation and John Douglas French Alzheimer's Foundation Maggie McKnight Russell-JDFAF Memorial Postdoctoral Fellowship. This work was supported by the National Institute on Neurologic Disorders and Stroke (1R01NS076794-01, to T.T.), an Alzheimer's Association Zenith Fellows Award (ZEN-10-174633, to T.T.), and an American Federation of Aging Research/Ellison Medical Foundation Julie Martin Mid-Career Award in Aging Research (M11472, to T.T.). We are grateful for startup funds from the Zilkha Neurogenetic Institute, which helped to make this work possible. &#8195;

Statement of research ethics: All experiments involving animals detailed herein were approved by the University of Southern California Institutional Animal Care and Use Committee (IACUC) and performed in strict accordance with National Institutes of Health guidelines and recommendations from the Association for Assessment and Accreditation of Laboratory Animal Care International.
1. Rodent Brain Isolation and Preparation for Immunostaining
DAY 1:
<ol>
	<li>Place aged TgF344-AD rats (14-month-old) or APP/PS1 mice (12-month-old) under continuous deep isoflurane anesthesia (4%). Assess the depth of anesthesia by toe pinch and the absence of withdrawal reflex.</li>
	<li>Cut through both sides of the rib cage and lift to expose the heart. Insert a 23 G needle into the left ventricle of the heart and make a small incision into the right atrium. Proceed to exsanguination by transcardial perfusion with ice-cold phosphate-buffered saline (PBS) using a peristaltic pump (30 mL&#160;for mice;&#160;150 - 200 mL&#160;for rats).</li>
	<li>Make a caudal midline incision into the skin and move the skin and muscle aside. Cut through the top of the skull along the midline and between the eyes. Remove the bone plates and isolate the whole brain from the skull.</li>
	<li>Place the brain into a coronal rodent brain matrix and slice it into quarters. Incubate posterior quarters O/N (16 h) in paraformaldehyde fixative (4% PFA in PBS) at 4 &#176;C. Wash 3x in PBS, and then transfer to 70% ethanol. Caution: PFA is toxic and should be handled under a chemical hood with appropriate personal protection equipment.</li>
</ol>
DAY 2:
<ol start="5">
	<li>Place brain quarters into embedding cassettes and progressively dehydrate tissue in successively more concentrated 1 h ethanol baths (70%, 80%, 95%, and 100% x3).</li>
	<li>Clear ethanol from the tissue with three successive 100% xylene baths (1 h each). Caution: Xylene is toxic and should be handled under a chemical hood with appropriate personal protection equipment.</li>
	<li>Embed tissue in paraffin blocks after two molten paraffin wax baths (56 - 58 &#176;C, 90 min each).</li>
</ol>
DAY 3:
<ol start="8">
	<li>Cut 10 &#956;m-thick sections of paraffin-embedded brains using a microtome. Dip sections into a water bath (50 &#176;C for 1 min) and apply to microscope slides. Leave the slides to dry O/N, ensuring tissue adhesion to the slide.</li>
</ol>
2. Immunostaining
Note: Different combinations of antibodies can be utilized for the staining procedure described below. Antibody cocktails compatible with brain tissue from rats and mice are listed in Table 1.
DAY 4:
<ol>
	<li>Deparaffinize brain sections using 2x 100% xylene baths (12 min each).</li>
	<li>Rehydrate brain sections in successive ethanol baths &#8212; 100% for 10 min, 95% for 5 min, 80% for 10 min, and finally 70% for 15 min &#8212; followed by 3x PBS washes [5 min at RT, with light agitation]. Meanwhile, heat antigen retrieval solution to 95 - 97 &#176;C on a hot plate with magnetic bar stirring.</li>
	<li>Incubate brain sections in antigen retrieval solution at 95 - 97 &#176;C for 30 min. Then, wash 3x in PBS (5 min at RT, with light agitation).</li>
	<li>Quickly dry slides using delicate task wipers to avoid tissue drying, and draw a hydrophobic barrier around the tissue area with a hydrophobic barrier pen. Fill the encircled tissue region with blocking buffer [PBS containing 0.3% Triton X-100 and 10% Normal Donkey Serum (NDS)], and incubate at RT for 1 h in a humidified chamber.</li>
	<li>Replace blocking buffer with Iba1 primary antibody (diluted in blocking buffer) to label mononuclear phagocytes, and incubate O/N at 4 &#176;C in a humidified chamber. For antibody hosts and working dilutions, see Table 1 and the Table of Materials.</li>
</ol>
DAY 5:
<ol start="6">
	<li>Rinse primary antibody with 3x PBS baths (5 min at RT with light agitation). Incubate with fluorescent secondary antibody (conjugated with a 594 nm emission fluorophore) for 1 h (in blocking buffer at RT in the dark) followed by 3x PBS baths (5 min at RT with light agitation). At this time, maintain sections in the dark to avoid fluorescent signal bleaching.</li>
</ol>
DAY 6 - 7:
<ol start="7">
	<li>Repeat steps 2.5 &#38; 2.6 with CD68 (rat brains) or LAMP1 (mouse tissue) antibodies and appropriate secondary antibodies (coupled with a 488 nm emission fluorophore) to label phagolysosomes.</li>
</ol>
DAY 7 - 8:
<ol start="8">
	<li>Repeat steps 2.5 &#38; 2.6 with OC (rat tissue) or 4G8 (mouse brains) antibodies and appropriate secondary antibodies (coupled to a 647 nm fluorophore) to label A&#946; deposits. 
	NOTE: Alternatively, 6E10 antibody can be used successfully both on mouse and rat tissue. For appropriate antibody combinations, see the Table of Materials.</li>
	<li>Allow sections to completely dry O/N at RT in the dark. Then, cover specimens with a cover slip sealed by fluorescence mounting media containing DAPI.</li>
</ol>
3. Acquisition of Large Z-stack Confocal Datasets
Note: This protocol requires a fully automated laser scanning confocal microscope equipped with a 60X objective and 405 nm, 488 nm, 594 nm, and 647 nm lasers. All equipment is computer controlled by imaging and laser control software. Prior to beginning the imaging protocol, power on the computer, epifluorescent lamp, microscope, lasers and camera.
DAY 9:
<ol>
	<li>Select the 60X microscope objective. Add immersion oil to the lens, and place the sample onto the microscope stage slide holder. Raise the objective until the oil makes contact with the slide. Adjust the focal plane to locate amyloid plaques in the hippocampus or cerebral cortex using epifluorescent illumination through the oculars.</li>
	<li>Acquire confocal images of activated mononuclear phagocytes surrounding amyloid deposits in the hippocampus or cortex of rodents by confocal microscopy (60X magnification, z-stack steps: 0.25 &#956;m &#60; z &#60; 0.40 &#956;m, number of steps 25 &#60; n &#60; 35).</li>
</ol>
4. q3DISM
Note: In order to yield significant results, we suggest analyzing a minimum of 3 images per animal/region of interest. For each image, the abundance of cells to analyze may vary depending on experimental paradigms. In the representative results shown in this report, we analyzed 3 cells/condition (e.g., mononuclear phagocytes distant from or associated with plaques; see Figures 1C - D and 2C - D).
DAY 10:
<ol>
	<li>Analyze confocal datasets with scientific 3D image processing and analysis software colocalization (coloc) module for spatial proximity of Iba1/CD68 (rat tissue) or Iba1/LAMP1 (mouse tissue) staining in all z-planes simultaneously. Create Iba+/CD68+ or Iba+/LAMP1+ colocalization channels that correspond to phagolysosomes within activated mononuclear phagocytes.
	<ol>
		<li>Select TRITC for channel A (corresponding to Iba1 staining coupled with 594 nm fluorophore) and FITC for channel B (corresponding to CD68 or LAMP1 staining coupled with 488 nm fluorophore). On the right-hand side of the software window for &#39;mode check,&#39; select &#39;threshold,&#39; and for &#39;coloc intensities,&#39; select &#39;source channels&#39;.</li>
		<li>Click &#39;Edit&#39; to select &#39;coloc color&#39; on the right-hand side of the software window.</li>
		<li>For each channel independently, adjust thresholds to include specific staining and exclude background/non-specific signals. Once adjusted, do not change thresholds between images to ensure an unbiased analysis. The colocalized voxels (pixels from all z-stacks) will appear in the color selected in step 4.1.2 in all z-stacks simultaneously.</li>
		<li>Click &#39;build coloc channel&#39;. The colocalization channel created will appear in the display adjustment window.</li>
		<li>Click on the coloc channel to open channel statistics. The &#39;% of volume/material A above threshold colocalized&#39; represents the % of Iba1 signal (voxels corresponding to the 594 nm fluorophore) colocalized with LAMP1 or CD68 signal (voxels corresponding to the 488 nm fluorophore). More simply, this is the monocyte volume occupied by phagolysosomes (see Figures 1C and 2C). 
		NOTE: &#39;% of volume/material B above threshold colocalized&#39; corresponds to % of LAMP1 or CD68 signal colocalized with Iba1. This should be close to 100%, as phagolysosomes are intracellular structures. Values are based on ratio of signal from all z-stacks above threshold colocalized.</li>
	</ol>
	</li>
	<li>Using the coloc module, analyze the coloc channel created in step 4.1 for spatial proximity with OC (rat tissue) or 4G8 (mouse tissue) A&#946; signals. This allows for quantitation of A&#946; encapsulated within phagolysosomes.
	<ol>
		<li>Select the channel A coloc dataset (corresponding to the Iba1/CD68 or Iba1/LAMP1 coloc channel created in step 4.1) and Cy5 for channel B (corresponding to OC or 4G8 staining coupled with 647 nm fluorophore).</li>
		<li>Build a coloc channel as described in steps 4.1.2 to 4.1.5.</li>
		<li>Click on the coloc channel to open channel statistics. The &#39;% of volume/material A above threshold colocalized&#39; represents the % of Iba1/LAMP1 or Iba1/CD68 (voxels corresponding to the coloc channel built in step 4.1.5.) colocalized with OC or 4G8 signal (voxels corresponding to the 647 nm fluorophore). This is the phagolysosomal volume occupied by A&#946; (see Figures 1D and 2D). 
		NOTE: &#39;% of volume/material B above threshold colocalized&#39; corresponds with % of total A&#946; signal colocalized with phagolysosomes. This can be used to evaluate the fraction of total A&#946; deposits encapsulated within phagolysosomes (not shown in the present representative results).</li>
	</ol>
	</li>
	<li>Use the surpass module to reconstruct the confocal image stacks and generate 3D models of A&#946; encapsulated within monocyte phagolysosomes.
	<ol>
		<li>In the &#39;display adjustment&#39; window, select TRITC (to show only Iba1 staining). In the &#39;volume properties&#39; window, click &#39;add new surface&#39;.</li>
		<li>In step &#39;1/5 algorithm&#39;, in &#39;settings,&#39; select &#39;surface.&#39; Also, in &#39;color,&#39; select color type in palette or RGB and adjust transparency (red is set at 60% transparency in Figures 1B and 2B). Check box &#39;select region of interest&#39;. Click next.</li>
		<li>In Step &#39;2/5 region of interest,&#39; draw a window around the cell of interest by adjusting x, y and z coordinates (see white boxes in Figures 1A and 2A). Click next.</li>
		<li>In Step &#39;3/5 source channel&#39;, select the TRITC source channel. Check the box &#39;smooth,&#39; and set surface area detail level to 0.4 &#956;m. For &#39;thresholding,&#39; select absolute intensity. Click next.</li>
		<li>In Step &#39;4/5 threshold,&#39; adjust threshold so that the volume created overlaps perfectly with the TRITC channel signal. Click next.</li>
		<li>In Step &#39;5/5 classify surfaces,&#39; in section &#39;filter type,&#39; select objects depending on their size to be included or excluded from the volumes to be created. Click finish, execute all creation steps, and exit the wizard.</li>
		<li>Repeat steps 4.3.1 to 4.3.6 to create a 3D surface for the FITC channel (LAMP1+ or CD68+ phagolysosomes).</li>
		<li>Repeat steps 4.3.1 to 4.3.6 to create a 3D surface for the Cy5 channel (OC+ or 4G8+ A&#946; deposits).</li>
	</ol>
	</li>
</ol>

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L., Zheng, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Astrocyte-Microglia+Cross+Talk+through+Complement+Activation+Modulates+Amyloid+Pathology+in+Mouse+Models+of+Alzheimer's+Disease.">Astrocyte-Microglia Cross Talk through Complement Activation Modulates Amyloid Pathology in Mouse Models of Alzheimer's Disease.</a> J Neurosci. 36 (2), 577-589 (2016).</li><li>Novotny, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conversion+of+Synthetic+A&#946;+to+In+Vivo+Active+Seeds+and+Amyloid+Plaque+Formation+in+a+Hippocampal+Slice+Culture+Model.">Conversion of Synthetic A&#946; to In Vivo Active Seeds and Amyloid Plaque Formation in a Hippocampal Slice Culture Model.</a> J Neurosci. 36 (18), 5084-5093 (2016).</li><li>Tartaro, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+fluorescence-based+in+vivo+phagocytosis+assay+to+measure+mononuclear+phagocyte+system+function+in+the+rat.">Development of a fluorescence-based in vivo phagocytosis assay to measure mononuclear phagocyte system function in the rat.</a> J Immunotoxicol. 12 (3), 239-246 (2015).</li></ol>

The authors have nothing to disclose.

The protocol that we describe in this report for true 3D quantitation of A&#946; phagocytosis in vivo by mononuclear phagocytes relies on specific labeling of cellular and subcellular compartments as well as A&#946; deposits. Specifically, we use Iba1 (Ionized-calcium Binding Adaptor molecule 1), a protein that is involved in membrane ruffling and phagocytosis upon cell activation18,19, to stain cerebral mononuclear phagocytes. While Iba1+ cells are generally regarded ...

Alzheimer&#39;s Disease (AD), the most common age-related dementia1, is characterized by cerebral amyloid-&#946; (A&#946;) accumulation as &#34;senile&#34; &#946;-amyloid plaques, chronic low-level neuroinflammation, tauopathy, neuronal loss, and cognitive disturbance2. In AD patient brains, neuroinflammation is earmarked by reactive astrocytes and mononuclear phagocytes (referred to as microglia, although their central vs. peripheral origin remains unclear) surrounding A&#946; deposits3. As the innate immune sentinels of the CNS, microglia are centrally positioned to clear brain A&#946;. However, microglial recruitment to A&#946; plaques is accompanied by very little, if any, A&#946; phagocytosis4,5. One hypothesis is that microglia are initially neuroprotective by phagocytozing small assemblies of A&#946;. However, eventually these cells become neurotoxic as overwhelming A&#946; burden and/or age-related functional decline, provokes microglia into a dysfunctional proinflammatory phenotype, contributing to neurotoxicity and cognitive decline6.
Recent Genome-wide Association Studies (GWAS) have identified a cluster of AD risk alleles belonging to core innate immune pathways7 that modulate phagocytosis8-11. Consequently, the immune response to cerebral amyloid deposition has become a major area of interest, both in terms of understanding AD etiology and for developing new therapeutic approaches12-14. Yet, there is a vital need for methodology to evaluate A&#946; phagocytosis in vivo. To address this unmet need, we have developed quantitative 3D in silico modeling (q3DISM) to enable true 3D quantitation of cerebral A&#946; phagocytosis by mononuclear phagocytes in rodent models of Alzheimer-like disease.
Limited only by the extent to which they recapitulate disease, animal models have proven invaluable for understanding AD pathoetiology and for evaluating experimental therapeutics. Owing to the fact that mutations in the Presenilin&#160;(PS) and Amyloid Precursor Protein (APP) genes independently cause autosomal dominant AD, these mutant transgenes have been extensively used to generate transgenic rodent models. Transgenic APP/PS1 mice simultaneously coexpressing &#34;Swedish&#34; mutant human APP (APPswe) and &#916; exon 9 mutant human presenilin 1 (PS1&#916;E9) present with accelerated cerebral amyloidosis and neuroinflammation15,16. Further, we have generated bi-transgenic rats coinjected with APPswe and PS1&#916;E9 constructs (line TgF344-AD, on a Fischer 344 background). Unlike transgenic mouse models of cerebral amyloidosis, TgF344-AD rats develop cerebral amyloid that precedes tauopathy, apoptotic loss of neurons, and behavioral impairment17.
In this report, we describe a protocol for immunostaining microglia, phagolysosomes and A&#946; deposits in brain sections from APP/PS1 mice and TgF344-AD rats, and acquisition of large z-dimensional confocal images. We detail in silico generation and analysis of true 3D reconstructions from confocal datasets allowing quantitation of A&#946; uptake into microglial phagolysosomes. More broadly, the methodology that we detail here can be used to quantify virtually any form of phagocytosis in vivo.

<table><tbody><tr><td>Isoflurane</td><td>Abbott</td><td>NDC 0044-5260-05</td><td></td></tr><tr><td>Dissecting scissors</td><td>VWR</td><td>82027-582</td><td></td></tr><tr><td>Dissecting scissors Blunt tip</td><td>VWR</td><td>82027-588</td><td></td></tr><tr><td>Tweezers</td><td>VWR</td><td>94024-408</td><td></td></tr><tr><td>23 G needle</td><td>VWR</td><td>BD305145</td><td></td></tr><tr><td>peristaltic pump FH10</td><td>Thermo Scientific</td><td>72-310-010</td><td></td></tr><tr><td>PBS 10x</td><td>Bioland Scientific</td><td>PBS01-02</td><td>Phosphate-buffered Saline; Working concentration 1x</td></tr><tr><td>Adult Mouse Brain Matrix, Coronal slices, Stainless Steel 1 mm&amp;nbsp;</td><td>Kent Scientific</td><td>RBMS-200C</td><td></td></tr><tr><td>Adult Rat Brain Matrix, Coronal slices, Stainless Steel 1 mm&amp;nbsp;</td><td>Kent Scientific</td><td>RBMS-305C&amp;nbsp;</td><td></td></tr><tr><td>32% Paraformaldehyde aqueous solution (PFA)</td><td>EMS</td><td>15714-S</td><td>Caution: Toxic. Working concentration: 4% in PBS</td></tr><tr><td>Ethanol</td><td>VWR</td><td>89125-188</td><td>Various concentrations, see protocol</td></tr><tr><td>Tissue-Tek Uni-cassettes Sakura</td><td>VWR</td><td>25608-774</td><td></td></tr><tr><td>Embedding and Infiltration Paraffin</td><td>VWR</td><td>15147-839</td><td></td></tr><tr><td>Microtome Leica RM2125</td><td>Leica Biosystems</td><td></td><td></td></tr><tr><td>Disposable Microtome Blades&amp;nbsp;</td><td>VWR</td><td>25608-964</td><td></td></tr><tr><td>Water bath Leica HI 1210</td><td>Leica Biosystems</td><td></td><td></td></tr><tr><td>Micro slide Superfrost plus</td><td>VWR</td><td>48311-703</td><td></td></tr><tr><td>Xylene</td><td>Sigma-Aldrich</td><td>534056-4X4L</td><td>Caution: Toxic&amp;nbsp;</td></tr><tr><td>Target Retrieval Solution 10x</td><td>DAKO</td><td>S1699</td><td>Working concentration 1x</td></tr><tr><td>KimWipes</td><td>VWR</td><td>21905-026</td><td></td></tr><tr><td>Hydrophobic PAP pen</td><td>VWR</td><td>95025-252</td><td></td></tr><tr><td>Triton X-100</td><td>VWR</td><td>97062-208</td><td></td></tr><tr><td>Normal Donkey Serum (NDS)</td><td>Jackson Immuno</td><td>017-000-121</td><td></td></tr><tr><td>Coverslips</td><td>VWR</td><td>48393081</td><td></td></tr><tr><td>Prolong Gold antifade reagent with DAPI</td><td>Life Technologies</td><td>P36935</td><td></td></tr><tr><td>Glass Slide Rack</td><td>VWR</td><td>100492-942</td><td></td></tr><tr><td>Iba1 antibody (polyclonal, rabbit)</td><td>Wako</td><td>019-19741&amp;nbsp;</td><td>Working concentration 1:200</td></tr><tr><td>Iba1 antibody (polyclonal, goat)</td><td>LifeSpan Bioscience</td><td>LS-B2645</td><td>Working concentration 1:200</td></tr><tr><td>rat CD68 [KP1] antibody (monoclonal, mouse)</td><td>Abcam</td><td>ab955</td><td>Working concentration 1:200</td></tr><tr><td>mouse CD68 [FA-11] antibody (monoclonal, rat)</td><td>Abcam</td><td>ab53444</td><td>Working concentration 1:200</td></tr><tr><td>mouse CD107a (LAMP1) antibody (monoclonal, rat)</td><td>Affymetrix</td><td>14-1071</td><td>Working concentration 1:100</td></tr><tr><td>Beta-Amyloid, 17 - 24 (4G8) antibody (monoclonal, mouse)</td><td>Covance</td><td>SIG-39220</td><td>Working concentration 1:200</td></tr><tr><td>Beta-Amyloid, 1 - 16 (6E10) antibody (monoclonal, mouse)</td><td>Covance</td><td>SIG-39320</td><td>Working concentration 1:200</td></tr><tr><td>OC antibody (polyclonal, rabbit)</td><td>Gifted by D. H. Cribbs and C. G. Glabe (UC Irvine)</td><td>Working concentration 1:200</td><td></td></tr><tr><td>Alexa Fluor 488 mouse secondary antibody</td><td>Invitrogen</td><td>A-11001</td><td>Working concentration 1:1,000</td></tr><tr><td>Alexa Fluor 488 rat secondary antibody</td><td>Invitrogen</td><td>A-11006</td><td>Working concentration 1:1,000</td></tr><tr><td>Alexa Fluor 594 rabbit secondary antibody</td><td>Invitrogen</td><td>A-11037</td><td>Working concentration 1:1,000</td></tr><tr><td>Alexa Fluor 594 goat secondary antibody</td><td>Invitrogen</td><td>A-11080</td><td>Working concentration 1:1,000</td></tr><tr><td>Alexa Fluor 647 mouse secondary antibody</td><td>Invitrogen</td><td>A-21235</td><td>Working concentration 1:1,000</td></tr><tr><td>Alexa Fluor 647 rabbit secondary antibody</td><td>Invitrogen</td><td>A-21443</td><td>Working concentration 1:1,000</td></tr><tr><td>Immersion oil</td><td>Nikon&amp;nbsp;</td><td></td><td></td></tr><tr><td>A1 Confocal microscope</td><td>Nikon&amp;nbsp;</td><td></td><td></td></tr><tr><td>NIS Elements Advanced Research software</td><td>Nikon&amp;nbsp;</td><td></td><td></td></tr><tr><td>Imaris:Bitplane software version 7.6</td><td>Bitplane</td><td></td><td>&quot;coloc&quot; and &quot;supass&quot; modules are used.&amp;nbsp;Alternatively, the open-source freeware&amp;nbsp;ImageJ can be used for colocalization&amp;nbsp;analysis of confocal z-stacks datasets.</td></tr></tbody></table>

quantitative 3d in silico modeling (q3dism) of cerebral amyloid-beta phagocytosis in rodent models of alzheimer's disease

Neuroinflammation is now recognized as a major etiological factor in neurodegenerative disease. Mononuclear phagocytes are innate immune cells responsible for phagocytosis and clearance of debris and detritus. These cells include CNS-resident macrophages known as microglia, and mononuclear phagocytes infiltrating from the periphery. Light microscopy has generally been used to visualize phagocytosis in rodent or human brain specimens. However, qualitative methods have not provided definitive evidence of in vivo phagocytosis. Here, we describe quantitative 3D in silico modeling (q3DISM), a robust method allowing for true 3D quantitation of amyloid-&#946; (A&#946;) phagocytosis by mononuclear phagocytes in rodent Alzheimer&#39;s Disease (AD) models. The method involves fluorescently visualizing A&#946; encapsulated within phagolysosomes in rodent brain sections. Large z-dimensional confocal datasets are then 3D reconstructed for quantitation of A&#946; spatially colocalized within the phagolysosome. We demonstrate the successful application of q3DISM to mouse and rat brains, but this methodology can be extended to virtually any phagocytic event in any tissue.

Using the multi-stage methodology for q3DISM detailed above, we are able to quantify A&#946; uptake into monocyte phagolysosomes in the brains of APP/PS1 mice (Figure 1) and TgF344-AD rats (Figure 2). Therefore, the q3DISM methodology has enabled analysis of mononuclear phagocytes in mouse and rat models of AD. Interestingly, the volume occupied by CD68+ phagolysosomes is significantly increased in Iba1+ mononuclear phagocytes associ...

Watch this Scientific Journal Video about Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease at JoVE.com

Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

We developed a methodology for quantitative 3D in silico modeling (q3DISM) of cerebral amyloid-&#946; (A&#946;) phagocytosis by mononuclear phagocytes in rodent models of Alzheimer&#39;s disease. This method can be generalized for the quantitation of virtually any phagocytic event in vivo.

Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

Neuroinflammation is now recognized as a major etiological factor in neurodegenerative disease. Mononuclear phagocytes are innate immune cells responsible ...

quantitative-3d-silico-modeling-q3dism-cerebral-amyloid-beta

Research

JoVE Journal

Medicine

7.9K Views.  University of Southern California (USC). We developed a methodology for quantitative 3D in silico modeling (q3DISM) of cerebral amyloid-β (Aβ) phagocytosis by mononuclear phagocytes in rodent models of Alzheimer's disease. This method can be generalized for the quantitation of virtually any phagocytic event in vivo.

Video: Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

Detection of Neuritic Plaques in Alzheimer's Disease Mouse Model

Alzheimer's disease (AD) is the most common neurodegenerative disorder leading to dementia. Neuritic plaque formation is one of the pathological hallmarks of Alzheimer's disease. The central component of neuritic plaques is a small filamentous protein called amyloid &beta; protein (A&beta;)1, which is derived from sequential proteolytic cleavage of the beta-amyloid precursor protein (APP) by &beta;-secretase and &gamma;-secretase. The amyloid hypothesis entails that A&gamma;-containing plaques as the underlying toxic mechanism in AD pathology2. The postmortem analysis of the presence of neuritic plaque confirms the diagnosis of AD. To further our understanding of A&gamma; neurobiology in AD pathogenesis, various mouse strains expressing AD-related mutations in the human APP genes were generated. Depending on the severity of the disease, these mice will develop neuritic plaques at different ages. These mice serve as invaluable tools for studying the pathogenesis and drug development that could affect the APP processing pathway and neuritic plaque formation. In this protocol, we employ an immunohistochemical method for specific detection of neuritic plaques in AD model mice. We will specifically discuss the preparation from extracting the half brain, paraformaldehyde fixation, cryosectioning, and two methods to detect neurotic plaques in AD transgenic mice: immunohistochemical detection using the ABC and DAB method and fluorescent detection using thiofalvin S staining method.

One of the pathological characteristics of AD is the formation of Amyloid &#x03B2; protein positive neuritic plaques. In this protocol we describe two methods to detect neuritic plaques in transgenic AD model mice: immunohistochemical detection using the ABC and DAB method and fluorescent detection using thioflavin S staining method.

Alzheimer's disease (AD) is the most common neurodegenerative disorder leading to dementia. Neuritic plaque formation is one of the pathological hallmarks ...

Neuroscience

Establishment of a Valuable Mimic of Alzheimer's Disease in Rat Animal Model by Intracerebroventricular Injection of Composited Amyloid Beta Protein

Alzheimer&#39;s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and is accompanied by neuron loss and structure change. With the increase of AD patients worldwide, the pathology and treatment of the disease has become a focus in the International Pharmaceutical Industry. Thus, the establishment of the animal model to mimic AD in the laboratory is of great importance.
Here, we describe a detailed protocol for establishing a mimic of AD in a rat animal model though intracerebroventricular injection of amyloid beta protein 25-35 (A&#946;25-35) combined with aluminum trichloride (AlCl3) and anterodorsal thalamic nucleus injection of recombinant human transforming growth factor-&#946;1 (RHTGF-&#946;1) to rats. The related markers of AD were measured, including: spatial memory, neuronal structure and substructure, neuronal A&#946;, and neurofibrillary tangles (NFT) production. This rat model demonstrates spatial memory impairment, neuronal structure and substructure pathological changes, neuron intracellular A&#946; burden, and NFT aggregation, and provides a close mimic of the neuronal structure and function disorder to that of clinical AD patients. Thus, the presented AD rat modelprovides a valuable in vivo tool for exploring neuronal function, neuronal pathology, and drug screening of AD.

This is a protocol to mimic Alzheimer&#39;s Disease in rats by evaluation of spatial memory impairment, neuronal pathological changes, neuronal amyloid beta protein (A&#946;) burden, and neurofibrillary tangles aggregation, induced by the injection of A&#946;25-35 combined with aluminum trichloride and recombinant human transforming growth factor-&#946;1.

Alzheimer&#39;s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and is accompanied by neuron loss and structure ...

Behavior

Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the over-production of amyloid-beta and the deposition of amyloid-beta plaques in brain regions of the afflicted individuals. Throughout the years scientists have generated numerous Alzheimer&#8217;s disease mouse models that attempt to replicate the amyloid-beta pathology. Unfortunately, the mouse models only selectively mimic the disease features. Neuronal death, a prominent effect in the brains of Alzheimer&#8217;s disease patients, is noticeably lacking in these mice. Hence, we and others have employed a method of directly infusing soluble oligomeric species of amyloid-beta - forms of amyloid-beta that have been proven to be most toxic to neurons - stereotaxically into the brain. In this report we utilize male C57BL/6J mice to document this surgical technique of increasing amyloid-beta levels in a select brain region. The infusion target is the dentate gyrus of the hippocampus because this brain structure, along with the basal forebrain that is connected by the cholinergic circuit, represents one of the areas of degeneration in the disease. The results of elevating amyloid-beta in the dentate gyrus via stereotaxic infusion reveal increases in neuron loss in the dentate gyrus within 1 week, while there is a concomitant increase in cell death and cholinergic neuron loss in the vertical limb of the diagonal band of Broca of the basal forebrain. These effects are observed up to 2 weeks. Our data suggests that the current amyloid-beta infusion model provides an alternative mouse model to address region specific neuron death in a short-term basis. The advantage of this model is that amyloid-beta can be elevated in a spatial and temporal manner.

Here, we present a protocol for direct stereotaxic brain infusion of amyloid-beta. This methodology provides an alternative in vivo mouse model to address the short-term effects of amyloid-beta on brain neurons.

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the ...

Intracerebroventricular Injection of Amyloid-&#946; Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, progressive accumulation of A&#946; oligomers and plaques is observed. Such A&#946; abnormalities are believed to block long-term potentiation, impair synaptic function, and induce cognitive deficits. Clinical and experimental evidences have revealed that the acute increase of A&#946; levels in the brain allows development of Alzheimer-like phenotypes. Hence, a detailed protocol describing how to acutely generate an AD mouse model via the intracerebroventricular (ICV) injection of A&#946; is necessary in many cases. In this protocol, the steps of the experiment with an A&#946;-injected mouse are included, from the preparation of peptides to the testing of behavioral abnormalities. The process of preparing the tools and animal subjects before the injection, of injecting the A&#946; into the mouse brain via ICV injection, and of assessing the degree of cognitive impairment are easily explained throughout the protocol, with an emphasis on tips for effective ICV injection of A&#946;. By mimicking certain aspects of AD with a designated injection of A&#946;, researchers can bypass the aging process and focus on the downstream pathology of A&#946; abnormalities.

The amyloid-&#946; (A&#946;)-injected animal model enables the administration of a defined quantity and species of A&#946; fragments and reduces individual differences within each study group. This protocol describes the intracerebroventricular (ICV) injection of A&#946; without stereotactic instruments, enabling the production of Alzheimer-like behavioral abnormalities in normal mice.

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, ...

Assessment of Spontaneous Alternation, Novel Object Recognition and Limb Clasping in Transgenic Mouse Models of Amyloid-&#946; and Tau Neuropathology

Here we describe a staged, behavioral testing approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional motor behaviors in transgenic mouse models of &#946;-amyloidosis and tauopathy. The paradigm includes tests for spontaneous alternation in a Y-maze, novel object recognition, and limb clasping. These tests were selected because they: 1) interrogate function of cognitive or motor domains and the correlate neural circuitry relevant to the human disease state, 2) have clearly defined endpoints, 3) have easily implementable quality control checks, 4) can be run in a moderate throughput format, and 5) require little intervention by the investigator. These methods are designed for investigators looking to screen compounds for activity in short-term and working memory tasks, or functional motor behaviors associated with Alzheimer's disease mouse models. The methods described here use behavioral tests that engage a number of different brain regions including hippocampus and various cortical areas. Investigators that desire cognitive tests that specifically assess cognition mediated by a single brain region could use these techniques to supplement other behavioral tests.

Described here is a staged, behavioral screening approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional motor behaviors in transgenic mouse models of &#946;-amyloidosis and tauopathy. These methods are optimized to screen compounds for activity in short-term and working memory tasks.

Here we describe a staged, behavioral testing approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional ...

Detecting Amyloid-&#946; Accumulation via Immunofluorescent Staining in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease that contributes to 60-70% dementia around the world. One of the hallmarks of AD undoubtedly lies on accumulation of amyloid-&#946; (A&#946;) in the brain. A&#946; is produced from the proteolytic cleavage of the beta-amyloid precursor protein (APP) by &#946;-secretase and &#947;-secretase. In pathological circumstances, the increased &#946;-cleavage of APP leads to overproduction of A&#946;, which aggregates into A&#946; plaques. Since A&#946; plaques are a characteristic of AD pathology, detecting the amount of A&#946; is very important in AD research. In this protocol, we introduce the immunofluorescent staining method to visualize A&#946; deposition. The mouse model used in our experiments is 5&#215;FAD, which carries five mutations found in human familial AD. The neuropathological and behavioral deficits of 5xFAD mice are well-documented, which makes it a good animal model to study A&#946; pathology. We will introduce the procedure including transcardial perfusion, cryosectioning, immunofluorescent staining and quantification to detect A&#946; accumulation in 5&#215;FAD mice. With this protocol, researchers can investigate A&#946; pathology in an AD mouse model.

In the neuropathology of Alzheimer's disease, one of the most crucial characteristics is the deposition of amyloid-&#946;. In this protocol, we describe the method of immunofluorescent staining in 5&#215;FAD transgenic mouse to detect amyloid-&#946; accumulation in plaques. The process of perfusion, cryosectioning, staining and quantification will be described in detail.

Alzheimer's disease (AD) is a neurodegenerative disease that contributes to 60-70% dementia around the world. One of the hallmarks of AD undoubtedly lies ...

Full- versus Sub-Regional Quantification of Amyloid-Beta Load on Mouse Brain Sections

Extracellular accumulation of amyloid-beta (A&#946;) plaques is one of the major pathological hallmarks of Alzheimer's disease (AD), and is the target of the only FDA-approved disease-modifying treatment for AD. Accordingly, the use of transgenic mouse models that overexpress the amyloid precursor protein and thereby accumulate cerebral A&#946; plaques are widely used to model human AD in mice. Therefore, immunoassays, including enzyme-linked immunosorbent assay (ELISA) and immunostaining, commonly measure the A&#946; load in brain tissues derived from AD transgenic mice. Though the methods for A&#946; detection and quantification have been well established and documented, the impact of the size of the region of interest selected in the brain tissue on A&#946; load measurements following immunostaining has not been reported. Therefore, the current protocol aimed to compare the A&#946; load measurements across the full- and sub-regions of interest using an image analysis software. The steps involved in brain tissue preparation, free-floating brain section immunostaining, imaging, and quantification of A&#946; load in full- versus sub-regions of interest are described using brain sections derived from 13-month-old APP/PS1 double transgenic male mice. The current protocol and the results provide valuable information about the impact of the size of the region of interest on A&#946;-positive area quantification, and show a strong correlation between the A&#946;-positive area obtained using the full- and sub-regions of interest analyses for brain sections derived from 13-month-old male APP/PS1 mice that show widespread A&#946; deposition.

The present protocol describes and compares the procedure to perform a full-region or sub-region of interest analysis of sagittal mouse brain sections to quantify amyloid-beta load in the APP/PS1 transgenic mouse model of Alzheimer's disease.

Extracellular accumulation of amyloid-beta (A&#946;) plaques is one of the major pathological hallmarks of Alzheimer's disease (AD), and is the target of ...

Fabrication of Amyloid-&#946;-Secreting Alginate Microbeads for Use in Modelling Alzheimer's Disease

According to the amyloid cascade hypothesis, the earliest trigger in the development of Alzheimer&#8217;s disease (AD) is the accumulation of toxic amyloid-&#946; (A&#946;) fragments, eventually leading to the classical features of the disease: amyloid plaques, neurofibrillary tangles and synaptic and neuronal loss. The lack of relevant non-transgenic preclinical models reflective of disease progression is one of the main factors hindering the discovery of effective drug treatments. To this end, we have developed a protocol for the fabrication of alginate microbeads containing amyloid-secreting cells useful for the study of the effects of chronic A&#946; production.
Chinese hamster ovary cells previously transfected with a human APP gene, secreting A&#946; (i.e., 7PA2 cells), were used in this study. A three-dimensional (3D) in vitro model for the sustained release of A&#946; was fabricated by encapsulation of 7PA2 cells in alginate. The process was optimized to target a bead diameter of 500-600 &#956;m for further in vivo studies. Optimization of 7PA2 cell encapsulation in alginate was performed altering fabrication parameters, e.g., alginate concentration, gel flow rate, electrostatic potential, head vibration frequency, gelling solution. Levels of secreted A&#946; were analyzed over time and compared between alginate beads and standard cell culture methods (up to 96 h).
A concentration of 1.5 x 106 7PA2 cells/mL and an alginate concentration of 2% (w/v) buffered with HEPES and subsequent gelation in 0.5 M calcium chloride for 5 min were found to fabricate the most stable microbeads. Fabricated microbeads were 1) of uniform size, 2) with an average diameter of 550 &#956;m, 3) containing about 100-150 cells per microbead and 4) able to secrete A&#946;.
In conclusion, our optimized method for the production of stable alginate microbeads containing amyloid-producing 7PA2 cells might enable the modeling of important aspects of AD both in vitro and in vivo.

This protocol illustrates a cell encapsulation method by rapid physical gelation of alginate to immobilize cells. Obtained microbeads allow controlled and sustained secretion of amyloid-&#946; over time and can be used to study the effects of secreted amyloid-&#946; in in vitro and in vivo models.

According to the amyloid cascade hypothesis, the earliest trigger in the development of Alzheimer&#8217;s disease (AD) is the accumulation of toxic ...

Biology

Establishing an Alzheimer's Disease Rat Model Through an Amyloid-Beta Peptide Injection

Source: Xiaoguang, W., et al. <a href="https://app.jove.com/v/56157">Establishment of a Valuable Mimic of Alzheimer&#39;s Disease in Rat Animal Model by Intracerebroventricular Injection of Composited Amyloid Beta Protein.</a> J. Vis. Exp. (2018).
This video demonstrates the procedure for injecting amyloid-beta peptides, aluminum chloride, and a neuroinflammatory growth factor, which collectively aids in toxic amyloid plaque formation in the hippocampus region. This causes memory impairment in the rat, characteristic of Alzheimer&#39;s disease.

Ustalenie modelu szczurzego choroby Alzheimera poprzez wstrzyknięcie peptydu beta-amyloidu

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
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JoVE Encyclopedia of Experiments

Neuropathology

Neurodegenerative Diseases

Direct Stereotaxic Brain Infusion of Amyloid-Beta Proteins for an Alzheimer's Disease Model

Source: Jean, Y. Y. et al., <a href="https://app.jove.com/v/52805">Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus.</a> J. Vis. Exp. (2015)
This video demonstrates the precise stereotaxic infusion of amyloid beta into the dentate gyrus to establish a mouse model of Alzheimer&#39;s disease. Accurate coordinate determination and controlled delivery of amyloid beta proteins result in neuronal degradation, disrupting memory processing and contributing to Alzheimer&#39;s disease development.

Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

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Detection of Neuritic Plaques in Alzheimer's Disease Mouse Model

Establishment of a Valuable Mimic of Alzheimer's Disease in Rat Animal Model by Intracerebroventricular Injection of Composited Amyloid Beta Protein

Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus

Intracerebroventricular Injection of Amyloid-β Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits

Assessment of Spontaneous Alternation, Novel Object Recognition and Limb Clasping in Transgenic Mouse Models of Amyloid-β and Tau Neuropathology

Detecting Amyloid-β Accumulation via Immunofluorescent Staining in a Mouse Model of Alzheimer's Disease

Full- versus Sub-Regional Quantification of Amyloid-Beta Load on Mouse Brain Sections

Fabrication of Amyloid-β-Secreting Alginate Microbeads for Use in Modelling Alzheimer's Disease

Ustalenie modelu szczurzego choroby Alzheimera poprzez wstrzyknięcie peptydu beta-amyloidu

Bezpośrednia stereotaktyczna infuzja białek beta amyloidu w mózgu dla modelu choroby Alzheimera