We express our great appreciation to Jiayi Sun and Lu Yang at Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, for the assistance with flow cytometry, Cuiping Chen at State Key Laboratory of Southwestern Chinese Medicine Resources, for the help with scanning electron microscopy. This work was supported by the National Natural Science Foundation of China [82104491], the Natural Science Foundation of Sichuan [2023NSFSC0674], and the Post-doctoral Science Foundation of China [2021M693789].

1. Cell line and cell culture
<ol>
	<li>Grow the human monocytic cell line THP-1 in RPMI-1640 complete culture medium with 10% fetal bovine serum, 1% penicillin-streptomycin and 0.05 mM &#946;-mercaptoethanol. Culture the cells at 37 &#176;C in 5% CO2 humidified air. Sub-culture cells every 2-3 days. 
	NOTE: THP-1 is a suspension cell, select to change half of the medium for sub-culturing. When observing many cell fragments under the light microscope, centrifuge at 300 x g for 3 min at room temperature. Resuspend cells in the pre-warmed fresh complete cell culture medium.</li>
	<li>Use cells (in passages 4-10) at the logarithmic growth phase for all experiments. When the cells are in good condition and logarithmic growth phase, they are round, bright, dense and without clumps and cell fragments under the light microscope at 100 x.</li>
</ol>
2. Differentiation of THP-1 cells
<ol>
	<li>Prepare a stock solution of PMA with a concentration of 1 mM (dissolve 1 mg of PMA in 1.62 mL of dimethyl sulfoxide). Dilute the PMA stock solution withcomplete cell culture medium to a final working concentration of 100 nM.</li>
	<li>Collect the cells in the culture dish into a 10 mL sterile centrifuge tube. Centrifuge at 300 x g for 3 min at room temperature, resuspend cells with 3 mL of complete culture medium containing PMA.</li>
	<li>Open the cell counter and the counting software. Pipette 20 &#181;L of cell suspension to the cell counter board and insert it into the cell counter board. Click Preview B1, turn the knob at the bottom right of the instrument, and adjust the focal distance to make the cells with bright center with clear contours on the software. Click Count to start counting.</li>
	<li>Based on the counting results, use complete culture medium containing PMA to adjust a cell density to 1 x 106 cells/mL. Seed cells in a 6 well plate, incubate the plate for 24 h at 37 &#176;C and 5% CO2 before starting further treatment.</li>
</ol>
3. Treatment of THP-1cells
<ol>
	<li>Prepare a stock solution of LPS with a concentration of 1 mg/mL (dissolve 1 mg of LPS in 1 mL of phosphate-buffered saline (PBS)). Dilute the LPS stock solution with serum-free medium to a final working concentration of 1 &#181;g/mL. Prepare a stock solution of Na2ATP with a concentration of 500 mM (dissolve 0.3026 g of ATP in 1 mL of PBS).</li>
	<li>Aspirate the PMA-containing medium from wells and wash with PBS 1x. Add serum-free medium to the control group and serum-free medium containing LPS to the model group. Incubate the plate for 6 h at 37 &#176;C + 5% CO2 before proceeding with further treatment.</li>
	<li>After 6 h, add the ATP stock solution to the model group to a final working concentration of 500 nM. Incubate the plate for 45 min at 37 &#176;C + 5% CO2 before proceeding.</li>
</ol>
4. Flow cytometry analysis (Method 1)
<ol>
	<li>Preparation of experimental samples
	<ol>
		<li>Seed and incubate cells in 6-well plates according to step 2. Establish four control groups with no treatment: one no-staining control, two single-staining controls (one for each stain), and one double-staining control. Establish one treatment group and treat according to step 3.</li>
		<li>After treatment, aspirate all the supernatant from the wells and wash with PBS 2x. Add 500 &#181;L of 0.05% Trypsin (non-EDTA) to each well, and incubate in the incubator for 30 s.</li>
		<li>Add 1 mL of RPMI-1640 complete culture medium to each well to stop cell detaching and collect the cells into the 5 mL tube. Centrifuge at 300 x g for 3 min at room temperature.</li>
		<li>Add 1 mL of PBS to resuspend cells. Place tubes with cells in a water bath at 37 &#176;C for 3 min. Centrifuge all samples at 300 x g for 3 min at room temperature.</li>
		<li>Dilute 200 &#181;L of 5x binding buffer with 800 &#181;L of distilled water to 1x binding buffer. Add 100 &#181;L of 1x binding buffer to resuspend cells and transfer the cells into the 5 mL tube.</li>
		<li>Add 5 &#181;L of Annexin V-PE solution to one tube of control group cells for 10 min and 5 &#181;L of 7-AAD solution to another tube of control group cells for 5 min (as single staining controls separately). Gently vortex each tube to mix dye and incubate the samples at room temperature protected from light. Add 400 &#181;L of PBS to each tube and vortex gently to terminate incubation.</li>
		<li>Add 5 &#181;L of Annexin V-PE solution to the remaining tubes and incubate for 5 min at room temperature. Gently vortex each tube to mix dye and incubate the samples at room temperature protected from light. After 5 min, add 5 &#181;L of 7-AAD solution for 5 min at room temperature. Add 400 &#181;L of PBS to each tube and vortex gently to terminate the incubation.</li>
		<li>Filter the cell suspension using a 35 &#181;m nylon mesh that are part of the 5 mL polystyrene round-bottom tubes. Place the tube on ice and wait for testing. Gently mix before testing and then insert it into the instrument.</li>
	</ol>
	</li>
	<li>Flow cytometry
	<ol>
		<li>Use fluorescence-activated cell sorting flow cytometer for testing. Open the flow cytometer data analysis software and confirm the performance of the detector and laser. Click the Cytometer and choose Fluidics startup, wait for the system to be ready. Exclude flow chamber bubbles by clicking on Cytometer &#62; Clean Modes &#62; De-gas Flow cell.</li>
		<li>Click Experiment, select in sequence New folder, Experiment, Specimen, Tube and Edit Name. A pentagonal shaped arrow in front of the tube, turns green when light up.</li>
		<li>Click on the icon of Cytometer FACSCelesta (a shortcut key icon), select Parameter, and then select FSC, SSC and PE signal. Click on the icon of Global Worksheet (a shortcut key icon) to establish PE histogram. For the flow cytometer used in this study, use PE for Annexin V at 586 nm and plot on the X-axis; PerCP-Cy5.5 for 7-AAD at 700 nm and plot on the Y-axis.</li>
		<li>Insert unstained control sample first into the instrument. Click on the icon of Acquisition Dashboard (a shortcut key icon), acquire a minimum of 10,000 events from the desired population. Exclude debris using a gate (P1) on an FSC-A and SSC-A dot plot. Adjust flow rate to Middle speed and Record Data. Adjust voltage to place cell population on the diagonal of the FSC/SSC histogram and click Restart. Adjust flow rate to Middle speed and Record Data.</li>
		<li>Click Next tube, run single staining controls of Annexin V and 7-AAD to adjust compensation. Run the remaining tubes and collect data.</li>
	</ol>
	</li>
</ol>
5. SEM imaging (Method 2)
<ol>
	<li>Preparation of experimental samples
	<ol>
		<li>Seed and incubate cells in 6-well plates according to step 2 and treat according to step 3.</li>
		<li>After treatment, aspirate all the supernatant from the wells and wash 2x with PBS. Add 500 &#181;L of 0.05% Trypsin (non-EDTA) to each well, and incubate in the incubator for 30 s.</li>
		<li>Add 1 mL of RPMI-1640 complete culture medium to each well to stop cell detaching and collect the cells into the 5 mL tube. Centrifuge at 300 x g for 3 min at room temperature.</li>
		<li>Fix cells with 500 &#181;L of electron microscope fixative (2.5% glutaric dialdehyde, 100 mM phosphorous salts) for 2 h at room temperature, followed by overnight at 4 &#176;C.</li>
		<li>Prepare chromium alum solution: Add 1.0 g of gelatin to 100 mL of ultrapure water, 70 &#176;C water-bath heating, and stir evenly. Add 0.05 g of chromium alum, stir evenly and filter with filter paper. Dip the clean cover glass in chromium alum solution for 2 h at 37 &#176;C and dry it in a 37 &#176;C oven for later use. 
		NOTE: The purpose is to prevent cell detachment during the experiment.</li>
		<li>Collect cells from fixed solution. Centrifuge at 300 x g for 3 min at room temperature. Add 100 &#181;L of PBS and gently blow away the cells. Drop the cell suspension onto the cover glass, allow to stand for 5 min. Aspirate all the supernatant and wash 3x with PBS for 5 min each time. 
		NOTE: The operation must be performed gently to prevent cell detachment. Do not shake vigorously, move slowly, and add liquid slowly along the wall.</li>
		<li>Add 500 &#956;L of 1% osmic&#160;acid fixation for 1 hour. Aspirate all the&#160;supernatant and wash 3x with PBS for 5 min&#160;each time.</li>
		<li>Dehydrate the samples successively in a series of ethanol (EtOH) concentrations (30%, 50%, 70%, 80%, 90%, 95%, 100%, 100%) for 15 min per EtOH solution. 
		NOTE: The cover glasses can&#160;be kept in 100% EtOH for several days at 4 &#176;C&#160;but it should dry as soon as possible to avoid&#160;excessive dehydration.</li>
		<li>Switch on the critical point dryer, open the CO2 tank, cool the chamber to 10 &#176;C. Quickly wrap the sample with filter paper when the chamber pressure is 0 psi and put it into the chamber.</li>
		<li>Open the inlet valve, observe through CO2 observation window, raise the liquid CO2 level between the two red lines (Do not exceed the upper limit), close the inlet valve. Soak the sample for 10 min. Open the inlet and exhaust valves simultaneously to equalize the CO2 for 1 min (liquid CO2 displaces EtOH). Close the exhaust valve to raise the liquid CO2 level to the specified position, close the inlet valve.</li>
		<li>Set the temperature to 35 &#176;C and pressure at 1250 psi. Once the temperature and pressure stabilize, depressurize at 100 psi/min. Take out the sample when the chamber pressure is zero and switch off the instrument.</li>
		<li>Mount specimens on SEM aluminum specimen holders using conductive tape. Employ a sputter coater tocover the samples with a layer (2-5 nm) of gold.</li>
	</ol>
	</li>
	<li>Imaging
	<ol>
		<li>Use high resolution cold field emission SEM for imaging. Set the accelerating voltage of SEM to 3 kV. Set the working distance to 10 mm. Set the magnification to 1,000x to observe the panorama. Set the magnification to 5,000x and 20,000x to locate the plasma membrane and image the sample. 
		NOTE: The process of visualizing PMA-differentiated THP-1 macrophages via SEM is similar to other types of cells and tissues and depends on the instruments used. The reference14 provides a detailed SEM protocol with accompanying videos.</li>
	</ol>
	</li>
</ol>

Analyzing LPS/ATP-Triggered Cell Death Mechanisms in THP-1 Cells

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The authors have nothing to disclose.

In this manuscript, two methods were used to detect LPS and ATP-induced death of PMA-differentiated THP-1 macrophages. Annexin V/7-AAD double staining was used, and the results were analyzed by flow cytometry from overall staining. As with other flow cytometric analysis, a group of unstained cells and two groups of single-stained cells were set up to exclude false positive and false negative results. The results show that after LPS/ATP stimulation, several cells lost membrane integrity, indicating that cell death may hav...

Cell death is a fundamental physiological process in all living organisms. In recent years, substantial studies have shown that cell death is involved in the immunity and balance within the organism. Studying cell death helps us better understand the onset and development of diseases. Several forms of programmed cell death have been described, and some key targets in these processes have been identified. Pyroptosis, apoptosis, and necroptosis are the three genetically defined programmed cell death pathways involved in internal balance and disease1.
Pyroptosis is characterized by the formation of membrane pores and the release of cell contents. Activated caspases or granzymes cleave gasdermins to separate their N-terminal domains, which then oligomerize, bind to the membrane, and form pores2,3,4. The gasdermin pore provides an atypical secretion channel across cellular membranes, resulting in downstream cell responses, including content release and ion influx2,3,4. Ultimately, the cells eventually experience plasma membrane rupture and pyroptotic lysis facilitated by ninjurin-15. In apoptosis, activated Bax and Bak form oligomers on the mitochondrial outer membrane and release cytochrome C, which is regulated by a balance between proapoptotic and antiapoptotic proteins of the BCL-2 family, initiator caspases (caspase-8, -9 and -10) and effector caspases (caspase-3, -6 and -7)1,6,7. The morphological changes of apoptosis include membrane blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and apoptotic body formation6,8. The receptor-interacting serine/threonine-protein kinase 1 (RIPK3) and mixed-lineage kinase domain-like (MLKL) are two downstream core components of the necroptotic mechanism1. RIPK3 recruits and phosphorylates MLKL, p-MLKL oligomerizes, associates with the cell membrane, initiates membrane perforations, causes ion influx, increases intracellular osmolarity, and eventually cell rupture6,9. Gasdermins and MLKL bind to the plasma membrane and mediate pyroptosis and necroptosis, respectively, while BAX/BAK mediates apoptosis by binding to the outer membrane of mitochondria6.
Although each pathway has specific mechanisms and outcomes, they lead to similar changes on the cell membrane. Under normal circumstances, phosphatidylserine (PS) is only localized in the inner leaflet of the plasma membrane. However, in the early stages of pyroptosis, apoptosis, and necroptosis, PS will be exposed, outside of the plasma membrane. Caspase-3/caspase-7 activates TMEM16 and XKR families, which leads to an asymmetrical cell membrane and externalizes&#160;PS during apoptosis10. Gasdermin D-mediated and MLKL-mediated Ca2+ influx leads to loss of the symmetry of the phospholipid bilayer on the cell membrane and the exposure of PS. The exposure occurs before the loss of cell membrane integrity11,12. Based on the similar changes in the membrane of these three types of programmed cell death, we use flow cytometry to analyze Annexin V/7-Aminoactinomycin D (7-AAD) double staining to detect cell death. Annexin V, a calcium-dependent phospholipid-binding protein, has a high affinity for PS, which can serve as a sensitive probe to detect exposed PS on the surface of the plasma membrane13. 7-AAD is a nucleic acid stain that cannot pass through the entire cell membrane. It is similar to propidium iodide (PI), a commonly used nucleic acid dye. They have similar fluorescence characteristics, but 7-AAD has a narrower emission spectrum and less interference with other detection channels. Owing to these similarities, it is not sufficient to distinguish between pyroptosis, apoptosis, and necroptosis. We used flow cytometry to detect the cell death from whole cells. A second method is used to capture the cell membrane using scanning electron microscopy (SEM) to observe the possible forms of cell death in individual cells.
We established a lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced phorbol-12-myristate-13-acetate (PMA)-differentiated lipid deposition in human monocyte (THP-1) macrophage model to observe cell death. This protocol focuses on observing cell death rather than investigating mechanisms.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.25% pancreatic enzyme solution (excluding EDTA)</td>
			<td>BOSTER Biological Technology co.ltd</td>
			<td>PYG0068</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Polystyrene Round-Bottom Tube</td>
			<td>CORNING</td>
			<td>352235</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL centrifuge tube</td>
			<td>Labgic Technology Co., Ltd.&#160;</td>
			<td>BS-50-M</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plate&#160;</td>
			<td>Sorfa Life Science Research Co.,Ltd</td>
			<td>220100</td>
			<td></td>
		</tr>
		<tr>
			<td>Annexin V-PE/7-AAD apoptosis analysis kit</td>
			<td>Absin (Shanghai) Biological Technology co.ltd</td>
			<td>abs50007</td>
			<td>Annexin V-PE, 7-AAD, 5&#215;Binding buffer, Apoptosis Positive Control Solution</td>
		</tr>
		<tr>
			<td>celculture CO2 incubator</td>
			<td>Esco (Shanghai) Enterprise Development Co., Ltd.</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>cell culture dish, 100 mm</td>
			<td>Sorfa Life Science Research Co.,Ltd</td>
			<td>230301</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellometer K2 Fluorescent Cell Counter</td>
			<td>Nexcelom Bioscience LLC</td>
			<td>Cellometer K2</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellometer SD100 Counting Chambers</td>
			<td>Nexcelom Bioscience LLC</td>
			<td>CHT4-SD100-002</td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge machine</td>
			<td>Hunan Xiangyi Laboratory Instrument Development Co., Ltd</td>
			<td>L530</td>
			<td></td>
		</tr>
		<tr>
			<td>chromium alum&#160;</td>
			<td>Guangdong Wengjiang Chemical Reagent Co., Ltd.</td>
			<td>PA04354</td>
			<td></td>
		</tr>
		<tr>
			<td>cover glasses, 9 mm</td>
			<td>Labgic Technology Co., Ltd.&#160;</td>
			<td>BS-09-RC</td>
			<td></td>
		</tr>
		<tr>
			<td>critical point dryer</td>
			<td>Quorum Technologies</td>
			<td>K850</td>
			<td></td>
		</tr>
		<tr>
			<td>dimethyl sulfoxide</td>
			<td>BOSTER Biological Technology co.ltd</td>
			<td>PYG0040</td>
			<td></td>
		</tr>
		<tr>
			<td>electron microscope fixative</td>
			<td>Servicebio Technology co.ltd&#160;</td>
			<td>G1102</td>
			<td>2.5% glutaric dialdehyde, 100 mM phosphorous salts</td>
		</tr>
		<tr>
			<td>electronic balance</td>
			<td>SHIMADZU</td>
			<td>ATX124</td>
			<td></td>
		</tr>
		<tr>
			<td>ethanol absolute</td>
			<td>Chengdu Kelong Chemical Co., Ltd</td>
			<td>2021033102</td>
			<td></td>
		</tr>
		<tr>
			<td>flow cytometer</td>
			<td>Becton,Dickinson and Company</td>
			<td>FACSCanto <img alt="Equation 1" src="/files/ftp_upload/66831/66831eq01.jpg" style="margin: auto;" /></td>
			<td></td>
		</tr>
		<tr>
			<td>flow cytometry analysis software</td>
			<td>Becton,Dickinson and Company</td>
			<td>BD FACSDivaTM Software</td>
			<td></td>
		</tr>
		<tr>
			<td>gelatin</td>
			<td>Guangdong Wengjiang Chemical Reagent Co., Ltd.</td>
			<td>PA00256&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>High resolution cold field emission scanning electron microscope</td>
			<td>TITACHI</td>
			<td>Regulus 8100</td>
			<td></td>
		</tr>
		<tr>
			<td>human monocytic cell line THP-1</td>
			<td>Procell Life Science&#38;Technology Co.,Ltd.</td>
			<td>CL0233</td>
			<td></td>
		</tr>
		<tr>
			<td>inverted microscope&#160;</td>
			<td>Leica Microsystems Co., Ltd</td>
			<td>DMi1</td>
			<td></td>
		</tr>
		<tr>
			<td>IR Vortex Mixer</td>
			<td>VELP Scientifica Srl</td>
			<td>ZX4</td>
			<td></td>
		</tr>
		<tr>
			<td>lipopolysaccharide&#160;</td>
			<td>Beijing Solarbio Science &#38; Technology Co.,Ltd.&#160;</td>
			<td>L8880</td>
			<td>LPS is derived from Escherichia coli 055:B5</td>
		</tr>
		<tr>
			<td>Na2ATP</td>
			<td>Beijing Solarbio Science &#38; Technology Co.,Ltd.&#160;</td>
			<td>A8270</td>
			<td></td>
		</tr>
		<tr>
			<td>phorbol-12-myristate-13-acetate&#160;</td>
			<td>Beijing Solarbio Science &#38; Technology Co.,Ltd.&#160;</td>
			<td>P6741</td>
			<td></td>
		</tr>
		<tr>
			<td>phosphate-buffered saline</td>
			<td>Servicebio Technology co.ltd&#160;</td>
			<td>G4202</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Eppendorf AG</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>pipette tips, 10 &#956;L</td>
			<td>Servicebio Technology co.ltd&#160;</td>
			<td>T-10PL</td>
			<td></td>
		</tr>
		<tr>
			<td>pipette tips, 1 mL&#160;</td>
			<td>Servicebio Technology co.ltd&#160;</td>
			<td>T-1250L</td>
			<td></td>
		</tr>
		<tr>
			<td>pipette tips, 200 &#956;L</td>
			<td>Servicebio Technology co.ltd&#160;</td>
			<td>T-200L</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI-1640 complete culture media</td>
			<td>Procell Life Science&#38;Technology Co.,Ltd.</td>
			<td>CM0233</td>
			<td>RPMI-1640 + 10% FBS + 0.05mM &#946;-mercaptoethanol + 1% P/S</td>
		</tr>
		<tr>
			<td>RPMI-1640 culture media&#160;</td>
			<td>Shanghai&#160;BasalMedia&#160;Technologies Co., LTD.</td>
			<td>K211104</td>
			<td></td>
		</tr>
		<tr>
			<td>sheath fluid</td>
			<td>BECKMAN COULTER</td>
			<td>8546733</td>
			<td></td>
		</tr>
		<tr>
			<td>sputter coater</td>
			<td>Cressington Scientific Instruments Ltd</td>
			<td>108</td>
			<td></td>
		</tr>
		<tr>
			<td>thermostatic water bath</td>
			<td>GUOHUA Electric Appliance CO.,Ltd&#160;</td>
			<td>HH-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

lps and atp-induced death of pma-differentiated thp-1 macrophages and its validation

Cell death is a fundamental process in all living organisms. The protocol establishes a lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced phorbol-12-myristate-13-acetate (PMA)-differentiated lipid deposition in human monocyte (THP-1) macrophage model to observe cell death. LPS combined with ATP is a classic inflammatory induction method, often used to study pyroptosis, but apoptosis and necroptosis also respond to stimulation by LPS/ATP. Under normal circumstances, phosphatidylserine is only localized in the inner leaflet of the plasma membrane. However, in the early stages of pyroptosis, apoptosis, and necroptosis, the cell membrane remains intact and exposed to phosphatidylserine, and in the later stages, the cell membrane loses its integrity. Here, flow cytometry was used to analyze Annexin V and 7-Aminoactinomycin D (AAD) double staining to detect the cell death from the whole cells. The results show&#160;that substantial cells died after stimulation with LPS/ATP. Using scanning electron microscopy, we observe the possible forms of cell death in individual cells. The results indicate that cells may undergo pyroptosis, apoptosis, or necroptosis after stimulation with LPS/ATP. This protocol focuses on observing the death of macrophages after stimulation with LPS/ATP. The results showed that cell death after LPS and ATP stimulation is not limited to pyroptosis and that apoptosis and necrotic apoptosis can also occur, helping researchers better understand cell death after LPS and ATP stimulation and choose a better experimental method.

The cell samples were treated as described in the protocol and flow cytometry detection was done. Normal cells cannot be stained with Annexin V and 7-AAD (Annexin V-/7-AAD-). In the early stages of pyroptosis, apoptosis, and necroptosis, PS was exposed and bound to Annexin V, but the cell membrane was still intact and excluded 7-AAD from the extracellular space (Annexin V+/7-AAD-). In the later stages, the cell membrane loses its integrity, cells are simultaneously stained by Annexin V and 7-AAD, showing double positive ...

Read this Scientific Article Protocol about Author Spotlight: THP-1 Macrophage Response to LPS/ATP - Unveiling Pyroptosis, Apoptosis and Necroptosis Spectrum at JoVE.com

Author Spotlight: THP-1 Macrophage Response to LPS/ATP &#8212; Unveiling the Pyroptosis, Apoptosis, and Necroptosis Spectrum

This protocol is based on LPS and ATP-induced death of PMA-differentiated THP-1 macrophages. We use flow cytometry to analyze Annexin V and 7-AAD double staining to detect cell death, using the whole cell and employing scanning electron microscopy to observe the cell membrane morphology.

LPS and ATP-induced Death of PMA-differentiated THP-1 Macrophages and its Validation

Cell death is a fundamental process in all living organisms. The protocol establishes a lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced ...

We are addressing LPS and ATP-introduced deaths of PMA-differentiated THP-1 macrophages. LPS and ATP-introduced deaths are not limited to pryoptosis but apoptosis and necroptosis can also occur. This will aid in a better understanding of cell death after LPS and ATP stimulation, and choosing more suitable experimental methods.Cryo-EM technology many studies the other structures in tissues, cells, and microorganisms. Cryo-EM provides neo native structure data for diverse molecular complexes. For example, using Cryo-Em techniques to perform 3D reconstruction can help us further understand the characteristic of apoptotic and necroptotic parts.Although pryoptosis is considered dominate in LPS and ATP-introduced cell death, one cannot determine the appropriation of these death forms or whether they all exist. Validating diverse cell death and measuring them will be our area of investigation in the future.

lps-atp-induced-death-pma-differentiated-thp-1-macrophages-its

Research

JoVE Journal

Biology

1.3K Views.  Chengdu University of Traditional Chinese Medicine. We are addressing LPS and ATP-introduced deaths of PMA-differentiated THP-1 macrophages. LPS and ATP-introduced deaths are not limited to pryoptosis but apoptosis and necroptosis can also occur. This will aid in a better understanding of cell death after LPS and ATP stimulation, and choosing more suitable experimental methods.Cryo-EM technology many studies the other structures in tissues, cells, and microorganisms. Cryo-EM provides neo native structure data for diverse molecular compl...

Video: Author Spotlight: THP-1 Macrophage Response to LPS/ATP — Unveiling the Pyroptosis, Apoptosis, and Necroptosis Spectrum

A &#946;-glucuronidase (GUS) Based Cell Death Assay

We have developed a novel transient plant expression system that simultaneously expresses the reporter gene, &beta;-glucuronidase (GUS), with putative positive or negative regulators of cell death. In this system, N. benthamiana leaves are co-infiltrated with a 35S driven expression cassette containing the gene to be analyzed, and the GUS vector pCAMBIA 2301 using Agrobacterium strain LBA4404 as a vehicle. Because live cells are required for GUS expression to occur, loss of GUS activity is expected when this marker gene is co-expressed with positive regulators of cell death. Equally, increased GUS activity is observed when anti-apoptotic genes are used compared to the vector control. As shown below, we have successfully used this system in our lab to analyze both pro- and anti-death players. These include the plant anti-apoptotic Bcl-2 Associated athanoGene (BAG) family, as well as, known mammalian inducers of cell death, such as BAX. Additionally, we have used this system to analyze the death function of specific truncations within proteins, which could provide clues on the possible post-translational modification/activation of these proteins. Here, we present a rapid and sensitive plant based method, as an initial step in investigating the death function of specific genes.

A &amp;#946;-glucuronidase GUS Based Cell Death Assay

Programmed cell death assays commonly used in mammalian systems such as DNA laddering or TUNEL assays, are often difficult to reproduce in plants. In combination with a GUS reporter system, we propose a rapid, plant based transient assay to analyze the potential death properties of specific genes.

We have developed a novel transient plant expression system that simultaneously expresses the reporter gene, &beta;-glucuronidase (GUS), with putative ...

Use of LysoTracker to Detect Programmed Cell Death in Embryos and Differentiating Embryonic Stem Cells

Programmed cell death (PCD) occurs in adults to maintain normal tissue homeostasis and during embryological development to shape tissues and organs1,2,6,7. During development, toxic chemicals or genetic alterations can cause an increase in PCD or change PCD patterns resulting in developmental abnormalities and birth defects3-5. To understand the etiology of these defects, the study of embryos can be complemented with in vitro assays that use differentiating embryonic stem (ES) cells.
Apoptosis is a well-studied form of PCD that involves both intrinsic and extrinsic signaling to activate the caspase enzyme cascade. Characteristic cell changes include membrane blebbing, nuclear shrinking, and DNA fragmentation. Other forms of PCD do not involve caspase activation and may be the end-result of prolonged autophagy. Regardless of the PCD pathway, dying cells need to be removed. In adults, the immune cells perform this function, while in embryos, where the immune system has not yet developed, removal occurs by an alternative mechanism. This mechanism involves neighboring cells (called "non-professional phagocytes") taking on a phagocytic role-they recognize the 'eat me' signal on the surface of the dying cell and engulf it8-10. After engulfment, the debris is brought to the lysosome for degradation. Thus regardless of PCD mechanism, an increase in lysosomal activity can be correlated with increased cell death.
To study PCD, a simple assay to visualize lysosomes in thick tissues and multilayer differentiating cultures can be useful. LysoTracker dye is a highly soluble small molecule that is retained in acidic subcellular compartments such as the lysosome11-13. The dye is taken up by diffusion and through the circulation. Since penetration is not a hindrance, visualization of PCD in thick tissues and multi-layer cultures is possible12,13. In contrast, TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) analysis14, is limited to small samples, histological sections, and monolayer cultures because the procedure requires the entry/permeability of a terminal transferase.
In contrast to Aniline blue, which diffuses and is dissolved by solvents, LysoTracker Red DND-99 is fixable, bright, and stable. Staining can be visualized with standard fluorescent or confocal microscopy in whole-mount or section using aqueous or solvent-based mounting media12,13. Here we describe protocols using this dye to look at PCD in normal and sonic hedgehog null mouse embryos. In addition, we demonstrate analysis of PCD in differentiating ES cell cultures and present a simple quantification method. In summary, LysoTracker staining can be a great complement to other methods of detecting PCD.

We present a simple protocol to visualize regions of programmed cell death (PCD) in mouse embryos and differentiating embryonic stem (ES) cell cultures using a highly soluble dye called LysoTracker.

Programmed cell death (PCD) occurs in adults to maintain normal tissue homeostasis and during embryological development to shape tissues and ...

Design and Analysis of Temperature Preference Behavior and its Circadian Rhythm in Drosophila

The circadian clock regulates many aspects of life, including sleep, locomotor activity, and body temperature (BTR) rhythms1,2. We recently identified a novel Drosophila circadian output, called the temperature preference rhythm (TPR), in which the preferred temperature in flies rises during the day and falls during the night 3. Surprisingly, the TPR and locomotor activity are controlled through distinct circadian neurons3. Drosophila locomotor activity is a well&#160;known circadian behavioral output and has provided strong contributions to the discovery of many conserved mammalian circadian clock genes and mechanisms4. Therefore, understanding TPR will lead to the identification of hitherto unknown molecular and cellular circadian mechanisms. Here, we describe how to perform and analyze the TPR assay. This technique not only allows for dissecting the molecular and neural mechanisms of TPR, but also provides new insights into the fundamental mechanisms of the brain functions that integrate different environmental signals and regulate animal behaviors. Furthermore, our recently published data suggest that the fly TPR shares features with the mammalian BTR3. Drosophila are ectotherms, in which the body temperature is typically behaviorally regulated. Therefore, TPR is a strategy used to generate a rhythmic body temperature in these flies5-8. We believe that further exploration of Drosophila TPR will facilitate the characterization of the mechanisms underlying body temperature control in animals.

Design and Analysis of Temperature Preference Behavior and its Circadian Rhythm in Drosophila

We recently identified a novel Drosophila circadian output, temperature preference rhythm (TPR), in which the preferred temperature in flies rises during the day and falls during the night. TPR is regulated independently from another circadian output, locomotor activity. Here&#160;we describe the design and analysis of TPR in Drosophila.

The circadian clock regulates many aspects of life, including sleep, locomotor activity, and body temperature (BTR) rhythms1,2. We recently identified a ...

A Method for Screening and Validation of Resistant Mutations Against Kinase Inhibitors

The discovery of BCR/ABL as a driver oncogene in chronic myeloid leukemia (CML) resulted in the development of Imatinib, which, in fact, demonstrated the potential of targeting the kinase in cancers by effectively treating the CML patients. This observation revolutionized drug development to target the oncogenic kinases implicated in various other malignancies, such as, EGFR, B-RAF, KIT and PDGFRs. However, one major drawback of anti-kinase therapies is the emergence of drug resistance mutations rendering the target to have reduced or lost affinity for the drug. Understanding the mechanisms employed by resistant variants not only helps in developing the next generation inhibitors but also gives impetus to clinical management using personalized medicine. We reported a retroviral vector based screening strategy to identify the spectrum of resistance conferring mutations in BCR/ABL, which has helped in developing the next generation BCR/ABL inhibitors. Using Ruxolitinib and JAK2 as a drug target pair, here we describe in vitro screening methods that utilizes the mouse BAF3 cells expressing the random mutation library of JAK2 kinase.

Emergence of genetic resistance against kinase inhibitor therapy poses significant challenge for effective cancer therapy. Identification and characterization of resistant mutations against a newly developed drug helps in better clinical management and next generation drug design. Here, we describe our protocol for in vitro screening and validation of resistant mutations.

The discovery of BCR/ABL as a driver oncogene in chronic myeloid leukemia (CML) resulted in the development of Imatinib, which, in fact, demonstrated the ...

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the Nucleoskeleton and Cytoskeleton (LINC complexes). These protein scaffolds span the nuclear envelope and connect the interior of the nucleus to components of the surrounding cytoplasmic cytoskeleton. LINC complexes consist of two evolutionary-conserved protein families, Sun proteins and Nesprins that harbor C-terminal molecular signature motifs called the SUN and KASH domains, respectively. Sun proteins are transmembrane proteins of the inner nuclear membrane whose N-terminal nucleoplasmic domain interacts with the nuclear lamina while their C-terminal SUN domains protrudes into the perinuclear space and interacts with the KASH domain of Nesprins. Canonical Nesprin isoforms have a variable sized N-terminus that projects into the cytoplasm and interacts with components of the cytoskeleton. This protocol describes the validation of a dominant-negative transgenic mouse strategy that disrupts endogenous SUN/KASH interactions in a cell-type specific manner. Our approach is based on the Cre/Lox system that bypasses many drawbacks such as perinatal lethality and cell nonautonomous phenotypes that are associated with germline models of LINC complex inactivation. For this reason, this model provides a useful tool to understand the role of LINC complexes during development and homeostasis in a wide array of tissues.

Nuclear envelope proteins play a central role in many basic biological processes and have been implicated in a variety of human diseases. This protocol describes a new Cre/Lox-based mouse model that allows for the spatiotemporal control of LINC complexes disruption.

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the ...

Interactome-Seq: A Protocol for Domainome Library Construction, Validation and Selection by Phage Display and Next Generation Sequencing

Folding reporters are proteins with easily identifiable phenotypes, such as antibiotic resistance, whose folding and function is compromised when fused to poorly folding proteins or random open reading frames. We have developed a strategy where, by using TEM-1 &#946;-lactamase (the enzyme conferring ampicillin resistance) on a genomic scale, we can select collections of correctly folded protein domains from the coding portion of the DNA of any intronless genome. The protein fragments obtained by this approach, the so called &#34;domainome&#34;, will be well expressed and soluble, making them suitable for structural/functional studies.
By cloning and displaying the &#34;domainome&#34; directly in a phage display system, we have showed that it is possible to select specific protein domains with the desired binding properties (e.g., to other proteins or to antibodies), thus providing essential experimental information for gene annotation or antigen identification.
The identification of the most enriched clones in a selected polyclonal population can be achieved by using novel next-generation sequencing technologies (NGS). For these reasons, we introduce deep sequencing analysis of the library itself and the selection outputs to provide complete information on diversity, abundance and precise mapping of each of the selected fragment. The protocols presented here show the key steps for library construction, characterization, and validation.

The protocols described allow the construction, characterization and selection (against the target of choice) of a &#34;domainome&#34; library made from any DNA source. This is achieved by a research pipeline that combines different technologies: phage display, a folding reporter and next generation sequencing with a web tool for data analysis.

Folding reporters are proteins with easily identifiable phenotypes, such as antibiotic resistance, whose folding and function is compromised when fused to ...

Histology Basics and Cell Death Detection in Honeybee Tissue

Honeybees (Apis mellifera L.) inside the hive (nurse workers and other hive bees) and outside the hive (foragers) are exposed to climate and weather changes, various pesticides, pathogens, and malnutrition, mainly entering through the mouth and primarily affecting the digestive tracts of adult bees. To understand and prevent the effects of such external and internal stressors on honeybees, one useful research method is the immunohistochemical method. A basic protocol is described to prepare the midgut (ventriculus) and hypopharyngeal glands (HPGs) of adult bees for histological analysis. A detailed methodology is described to assess the level of cell damage and distinguish necrosis from programmed cell death (apoptosis) as a natural process of tissue regeneration. The results of adult honeybee treatment with oxalic acid and pesticides (insecticide and acaricide) and the determination of cell death in the ventriculus and HPGs are presented. The pros and cons of the methodology are also discussed.

Immunohistochemical methods are useful in honeybee research to detect and assess the level of apoptosis and necrosis in the midgut and hypopharyngeal glands of adult bees.

Honeybees (Apis mellifera L.) inside the hive (nurse workers and other hive bees) and outside the hive (foragers) are exposed to climate and weather ...

Unveiling Inflammatory Arthritis&#58; Exploring Functions of Synovial Cells

Isolation and Culture of Primary Synovial Macrophages and Fibroblasts from Murine Arthritis Tissue

Rheumatoid arthritis is an autoimmune disease that leads to chronic inflammation of joints. Synovial macrophages and synovial fibroblasts have central roles in the pathogenesis of rheumatoid arthritis. It is important to understand the functions of both cell populations to reveal the mechanisms underlying pathological progression and remission in inflammatory arthritis. In general, in vitro experimental conditions should mimic the in vivo environment as much as possible. Primary tissue-derived cells have been used in experiments characterizing synovial fibroblasts in arthritis. In contrast, in experiments investigating the biological functions of macrophages in inflammatory arthritis, cell lines, bone marrow-derived macrophages, and blood monocyte-derived macrophages have been used. However, it is unclear whether such macrophages actually reflect the functions of tissue-resident macrophages. To obtain resident macrophages, previous protocols were modified to isolate and expand both primary macrophages and fibroblasts from synovial tissue in an inflammatory arthritis mouse model. These primary synovial cells may be useful for in vitro analysis of inflammatory arthritis.

Author Spotlight: Isolation and Culture of Primary Synovial Macrophages and Fibroblasts from Murine Arthritis Tissue  

The present study provides a modified protocol to isolate synovial macrophages and fibroblasts from murine inflammatory arthritis tissue.

Rheumatoid arthritis is an autoimmune disease that leads to chronic inflammation of joints. Synovial macrophages and synovial fibroblasts have central ...

Isolation of Synovial Macrophages

Quantifying Cell Death in Human Colonoids in Response to Cytotoxic Perturbagens

Quantification of Cytokine-Induced Cell Death in Human Colonic Organoids Using Live Fluorescence Microscopy

Intestinal epithelial cell (IEC) death is increased in patients with inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD). This can contribute to defects in intestinal barrier function, exacerbation of inflammation, and disease immunopathogenesis. Cytokines and death receptor ligands are partially responsible for this increase in IEC death. IBD-relevant cytokines, such as TNF-&#945; and IFN-&#947;, are cytotoxic to IECs both independently and in combination. This protocol describes a simple and practical assay to quantify cytokine-induced cytotoxicity in CD patient-derived colonic organoids using a fluorescent cell death dye (SYTOX Green Nucleic Acid Stain), live fluorescence microscopy, and open-source image analysis software. We also demonstrate how to use the Bliss independence mathematical model to calculate a coefficient of perturbagen interaction (CPI) based on organoid cytotoxicity. The CPI can be used to determine if interactions between cytokine combinations or other types of perturbagens are antagonistic, additive, or synergistic. This protocol can be implemented to investigate the cytotoxic activity of cytokines and other perturbagens using patient-derived colonic organoids.

Author Spotlight: Understanding Cytokine-Induced Cell Death in Intestinal Epithelial Cells Using Human Organoids

This protocol describes a simple and cost-effective method to investigate and quantify cell death in human colonic organoids in response to cytotoxic perturbagens such as cytokines. The approach employs a fluorescent cell death dye (SYTOX Green Nucleic Acid Stain), live fluorescence microscopy, and open-source image analysis software to quantify single-organoid responses to cytotoxic stimuli.

Intestinal epithelial cell (IEC) death is increased in patients with inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease ...