This work was supported by Grants-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology, Japan (#19H03430 and #17K09405 to M.O., and #19J11829 to K.S.), by a Grant-in-Aid for Scientific Research on Innovative Areas (#18H05024 to M.O.), by the Research Program on Hepatitis from Japan Agency for Medical Research and Development, AMED (to M.O., #JP19fk021005), by program on the Innovative Development and the Application of New Drugs for Hepatitis B (#JP19fk0310102 to K.K.) from AMED, by grants from the Japan Foundation for Applied Enzymology and from the Kobayashi Foundation for Cancer Research (to M.O.), by GSK Japan Research Grant 2018 (to K.S.), and by a grant from the Miyakawa Memorial Research Foundation (to K.S.).

NOTE: A schematic representation of the split luciferase assay is shown in Figure 1A, and the assay process is outlined in Figure 1B. The interaction dynamics can be measured in real time without cell lysis.
1. Cell Preparation
<ol>
	<li>Maintain cultured HEK293T cells in Dulbecco&#39;s modified Eagle&#39;s medium (DMEM) supplemented with 10% v/v fetal bovine serum (FBS), 1x penicillin/streptomycin at 37 &#176;C in 20% O2 and 5% CO2.</li>
	<li>Seed 5 x 106 cells into a 100 mm dish with 10 mL of DMEM and incubate at 37 &#176;C overnight.</li>
	<li>Transiently transfect 1 &#181;g of HBx and DDB1 with split luciferases into the cells according to the following method. 
	NOTE: The amount of the plasmid DNA transfected may depend on the transfection regent used. The optimal position of the split luciferase fused to the target protein must be determined beforehand. In this case, HBx fused to LgBit at the C-terminus of HBx (HBx-LgBit) and DDB1 fused to SmBit at the N-terminus of DDB1 (SmBit-DDB1) provided the best results (i.e., the brightest luciferase signals). This process has been reported previously in detail7.
	<ol>
		<li>Dilute 1 &#181;g of HBx-LgBit expressing DNA plasmid and 1 &#181;g of SmBit-DDB1 expressing DNA plasmid (Table of Materials) in DNA condensation buffer (Table of Materials) to a total volume of 300 &#181;L.</li>
		<li>Add 16 &#181;L of enhancer solution (Table of Materials) and mix by vortexing for 1 s.</li>
		<li>Incubate the sample at room temperature for 3 min.</li>
		<li>Add 60 &#181;L of transfection reagent (Table of Materials) to the sample and mix by vortexing for 10 s.</li>
		<li>Incubate the sample at room temperature for 8 min.</li>
		<li>During incubation, aspirate the culture medium from the dish (prepared in step 1.2), and wash cells with 5 mL of phosphate-buffered saline (PBS). Remove PBS by aspiration and add 7 mL of DMEM.</li>
		<li>Add 3 mL of DMEM to the tube containing the transfection complexes. Mix by pipetting and add the transfection complexes onto the cell in the 10 cm dish.</li>
	</ol>
	</li>
	<li>Incubate the cells at 37 &#176;C in an incubator under 5% CO2 for 10 h.</li>
	<li>Reseed the cells into a white 96 well plate at 5 x 104 cells/well in 50 &#181;L of medium/well according to the following method.
	<ol>
		<li>Remove the spent cell culture medium and wash cells with 5 mL of PBS.</li>
		<li>Remove PBS by aspiration, add 1 mL of 0.25% trypsin-EDTA, and incubate at 37 &#176;C for 5 min to detach cells.</li>
		<li>Add 4 mL of DMEM and disperse the medium by pipetting over the surface of the cell layer several times. Transfer the cell suspension to a tube.</li>
		<li>Centrifuge cells at 500 x g for 5 min at room temperature.</li>
		<li>Discard supernatant and resuspend the cell pellet in 1 mL of PBS.</li>
		<li>Centrifuge the cell suspension at 500 x g for 5 min at room temperature and discard supernatant.</li>
		<li>Dilute the cell pellet with buffered cell culture medium (Table of Materials) supplemented with 10% FBS to a seeding density of 1.0 x 106 cells/mL.</li>
		<li>Pipette 50 &#181;L of cell suspension into each well of a 96 well plate and return the cells to the incubator.</li>
	</ol>
	</li>
	<li>Incubate cells at 37 &#176;C under 5% CO2 for 10 h.</li>
</ol>
2. Compound Screening
<ol>
	<li>During the incubation, dilute the screening compounds (Table of Materials) and solvent (dimethyl sulfoxide [DMSO]) at 13.5x concentration. For example, if the stock is 10 mM and the screening concentration is 10 &#181;M, add 1 &#181;L of stock solution to 73.1 &#181;L of buffered cell culture medium.</li>
	<li>Add 12.5 &#181;L of luminescent substrate (Table of Materials) to each well and incubate for 5 min at room temperature. 
	NOTE: As negative controls, the wells at both ends of the plate (i.e., columns 1 and 12) should contain no luminescent substrate.</li>
	<li>Measure the baseline luminescence using a luminometer (Table of Materials).</li>
	<li>Immediately after the initial measurement, add 5 &#181;L of compounds and control DMSO diluted in step 2.1 to each well. 
	NOTE: The final concentration will be 10 &#181;M.</li>
	<li>Measure luminescence values every 30 min for 2 h. 
	NOTE: The plate should be incubated in the dark at room temperature.</li>
	<li>Calculate the inhibitory effects by comparison with control DMSO treatment after normalization to the baseline signals. 
	NOTE: Screening each compound in duplicate or triplicate can reduce variation.</li>
</ol>

<ol>
	<li>Tang, L. S. Y., Covert, E., Wilson, E., Kottilil, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+hepatitis+B+infection:+a+review.">Chronic hepatitis B infection: a review.</a> The Journal of the American Medical Association. 319, 1802-1813 (2018).</li><li>Sekiba, 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=Hepatitis+B+virus+pathogenesis:+Fresh+insights+into+hepatitis+B+virus+RNA.">Hepatitis B virus pathogenesis: Fresh insights into hepatitis B virus RNA.</a> World Journal of Gastroenterology. 24, 2261-2268 (2018).</li><li>Slagle, B. L., Bouchard, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepatitis+B+virus+X+and+regulation+of+viral+gene+expression.">Hepatitis B virus X and regulation of viral gene expression.</a> Cold Spring Harbor Perspectives in Medicine. 6, a021402 (2016).</li><li>Murphy, C. M., 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=Hepatitis+B+Virus+X+Protein+Promotes+Degradation+of+SMC5/6+to+Enhance+HBV+Replication.">Hepatitis B Virus X Protein Promotes Degradation of SMC5/6 to Enhance HBV Replication.</a> Cell Reports. 16, 2846-2854 (2016).</li><li>Decorsi&#232;re, A., 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=Hepatitis+B+virus+X+protein+identifies+the+Smc5/6+complex+as+a+host+restriction+factor.">Hepatitis B virus X protein identifies the Smc5/6 complex as a host restriction factor.</a> Nature. 531, 386-389 (2016).</li><li>Niu, C., 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=The+Smc5/6+complex+restricts+HBV+when+localized+to+ND10+without+inducing+an+innate+immune+response+and+is+counteracted+by+the+HBV+X+protein+shortly+after+infection.">The Smc5/6 complex restricts HBV when localized to ND10 without inducing an innate immune response and is counteracted by the HBV X protein shortly after infection.</a> PLoS One. 12, e0169648 (2017).</li><li>Sekiba, 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=Inhibition+of+HBV+Transcription+From+cccDNA+With+Nitazoxanide+by+Targeting+the+HBx-DDB1+Interaction.">Inhibition of HBV Transcription From cccDNA With Nitazoxanide by Targeting the HBx-DDB1 Interaction.</a> Cellular and Molecular Gastroenterology and Hepatology. 7, 297-312 (2019).</li><li>Eggers, C. T., 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=NanoLuc+Complementation+Reporter+Optimized+for+Accurate+Measurement+of+Protein+Interactions+in+Cells.">NanoLuc Complementation Reporter Optimized for Accurate Measurement of Protein Interactions in Cells.</a> ACS Chemical Biology. 11, 400-408 (2015).</li><li>Zhang, J. H., Chung, T. D. Y., Oldenburg, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+statistical+parameter+for+use+in+evaluation+and+validation+of+high+throughput+screening+assays.">A simple statistical parameter for use in evaluation and validation of high throughput screening assays.</a> Journal of Biomolecular Screening. 4, 67-73 (1999).</li><li>Rao, V. S., Srinivas, K., Sujini, G. N., Kumar, G. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein-protein+interaction+detection:+Methods+and+analysis.">Protein-protein interaction detection: Methods and analysis.</a> International Journal of Proteomics. 2014. 2014, 147648 (2014).</li><li>Michael, S., 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=A+Robotic+Platform+for+Quantitative+High-Throughput+Screening.">A Robotic Platform for Quantitative High-Throughput Screening.</a> ASSAY and Drug Development Technologies. 6, 637-657 (2008).</li><li>Skwarczynska, M., Ottmann, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein-protein+interactions+as+drug+targets.">Protein-protein interactions as drug targets.</a> Future Medicinal Chemistry. 7, 2195-2219 (2015).</li><li>de Chassey, B., Meyniel-Schicklin, L., Vonderscher, J., Andr&#233;, P., Lotteau, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Virus-host+interactomics:+New+insights+and+opportunities+for+antiviral+drug+discovery.">Virus-host interactomics: New insights and opportunities for antiviral drug discovery.</a> Genome Medicine. 6, 115 (2014).</li><li>Prasad, M., 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=Virus-Host+Interactions:+New+Insights+and+Advances+in+Drug+Development+Against+Viral+Pathogens.">Virus-Host Interactions: New Insights and Advances in Drug Development Against Viral Pathogens.</a> Current Drug Metabolism. 18, 942-970 (2017).</li></ol>

The authors have nothing to disclose.

We developed a convenient screening method using a split luciferase assay to find HBx-DDB1 binding inhibitors. The interaction dynamics can be detected in real time in living cells without the need for cell lysis. Inhibition of the HBx-DDB1 interaction leads to restoration of Smc5/6, which results in suppression of viral transcription, protein expression, and cccDNA production7. This novel mechanism of antiviral action may overcome the inadequacies of current HBV therapies.
<p class="jove_cont...

Hepatitis B virus (HBV) infection is a major public health concern worldwide, with annual estimates of 240 million people chronically infected with HBV and 90,000 deaths due to complications from the infection, including cirrhosis and hepatocellular carcinoma (HCC)1. Although the current anti-HBV therapeutic agents, nucleos(t)ide analogues, sufficiently inhibit viral reverse transcription, they rarely achieve elimination of viral proteins, which is the long-term clinical goal. Their poor effect on viral protein elimination is due to their lack of direct effect on viral transcription from episomal viral covalently closed circular DNA (cccDNA) minichromosomes in the hepatocyte nucleus2.
HBV transcription is activated by HBV regulatory X (HBx) protein3. Recent studies revealed that HBx degrades structural maintenance of chromosomes 5/6 (Smc5/6), a host restriction factor that blocks HBV transcription from cccDNA, via hijacking a DDB1-CUL4-ROC1 E3 ubiquitin ligase complex4,5,6. Therefore, a crucial step in promoting viral transcription from cccDNA is thought to be the HBx-DDB1 interaction. Compounds capable of inhibiting the binding between HBx and DDB1 may block viral transcription, and indeed nitazoxanide was identified as an inhibitor of the HBx-DDB1 interaction via a screening system developed in our laboratory7.
Here, we present our convenient screening system used to identify inhibitors of the HBx-DDB1 interaction, which utilizes a split luciferase complementary assay7,8. Split luciferase subunits are fused to HBx and DDB1, and the HBx-DDB1 interaction brings the subunits into close proximity to form a functional enzyme that generates a bright luminescent signal. As the interaction between the subunits is reversible, this system can detect rapidly dissociating HBx-DDB1 proteins (Figure 1). Using this system, a large compound library can be easily screened, which may result in the discovery of novel compounds capable of efficiently inhibiting the HBx-DDB1 interaction.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cell culture microplate, 96 well, PS, F-BOTTOM</td>
			<td>Greiner-Bio-One GmbH</td>
			<td>655098</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Sigma Aldrich</td>
			<td>D6046</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Tocris Bioscience</td>
			<td>3176</td>
			<td></td>
		</tr>
		<tr>
			<td>Effectene transfection reagent</td>
			<td>Qiagen</td>
			<td>301425</td>
			<td>Includes DNA-condensation buffer, enhancer solution and transfection reagent</td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Nichirei</td>
			<td>175012</td>
			<td></td>
		</tr>
		<tr>
			<td>GloMax 96 microplate luminometer</td>
			<td>Promega</td>
			<td>E6521</td>
			<td></td>
		</tr>
		<tr>
			<td>HBx&#8211;LgBit expressing DNA plasmid</td>
			<td>Our laboratory</td>
			<td></td>
			<td>Available upon request</td>
		</tr>
		<tr>
			<td>HEK293T cells</td>
			<td>American Type Culture Collection</td>
			<td>CRL-11268</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoBiT PPI starter systems</td>
			<td>Promega</td>
			<td>N2015</td>
			<td>Includes Nano-Glo Live Cell Reagent</td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>11058021</td>
			<td>Described as &#34;buffered cell culture medium&#34; in the manuscript</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Takara</td>
			<td>T900</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Sigma Aldrich</td>
			<td>P0781</td>
			<td></td>
		</tr>
		<tr>
			<td>Screen-Well FDA-approved drug library V2 version 1.0</td>
			<td>Enzo Life Sciences</td>
			<td>BML-2841</td>
			<td>Compounds used here were as follows: mequinol, mercaptopurine hydrate, mesna, mestranol, metaproterenol hemisulfate, metaraminol bitartrate, metaxalone, methacholine chloride, methazolamide, methenamine hippurate, methocarbamol, methotrexate, methoxsalen, methscopolamine bromide, methsuximide, methyclothiazide, methyl aminolevulinate&#183;HCl, methylergonovine maleate, metolazone, metyrapone, mexiletine&#183;HCl, micafungin, miconazole, midodrine&#183;HCl, miglitol, milnacipran&#183;HCl, mirtazapine, mitotane, moexipril&#183;HCl, mometasone furoate, mupirocin, nadolol, nafcillin&#183;Na, naftifine&#183;HCl, naratriptan&#183;HCl, natamycin, nebivolol&#183;HCl, nelarabine, nepafenac, nevirapine, niacin, nicotine, nilotinib, nilutamide, nitazoxanide, nitisinone, nitrofurantoin, nizatidine, nortriptyline&#183;HCl, olsalazine&#183;Na, orlistat, oxaprozin, oxtriphylline, oxybutynin Chloride, oxytetracycline&#183;HCl, paliperidone, palonosetron&#183;HCl, paromomycin sulfate, pazopanib&#183;HCl, pemetrexed disodium, pemirolast potassium, penicillamine, penicillin G potassium, pentamidine isethionate, pentostatin, perindopril erbumine, permethrin, perphenazine, phenelzine sulfate, phenylephrine, phytonadione, pimecrolimus, pitavastatin calcium, and podofilox</td>
		</tr>
		<tr>
			<td>SmBit&#8211;DDB1 expressing DNA plasmid</td>
			<td>Our laboratory</td>
			<td></td>
			<td>Available upon request</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA</td>
			<td>Sigma Aldrich</td>
			<td>T4049</td>
			<td></td>
		</tr>
	</tbody>
</table>

identifying inhibitors of the hbx-ddb1 interaction using a split luciferase assay system

There is an urgent need for novel therapeutic agents for hepatitis B virus (HBV) infection. Although currently available nucleos(t)ide analogs potently inhibit viral replication, they have no direct effect on the expression of viral proteins transcribed from a viral covalently closed circular DNA (cccDNA). As high viral antigen load may play a role in this chronic and HBV-related carcinogenesis, the goal of HBV treatment is to eradicate viral proteins. HBV regulatory protein X (HBx) binds to the host DNA damage-binding protein 1 (DDB1) protein to degrade structural maintenance of chromosomes 5/6 (Smc5/6), resulting in activation of viral transcription from cccDNA. Here, using a split luciferase complementation assay system, we present a comprehensive compound screening system to identify inhibitors of the HBx-DDB1 interaction. Our protocol enables easy detection of interaction dynamics in real time within living cells. This technique may become a key assay to discover novel therapeutic agents for treatment of HBV infection.

Representative outcomes following the use of this protocol are shown in Figure 2A,B. The signal-to-background ratio was greater than 80 and the Z&#39; factor9 (the gold standard quality index for high-throughput screening) was greater than 0.5, indicating that this assay system was acceptable for high-throughput screening. With the threshold set to &#62;40% inhibition compared with the control (DMSO only), we identifie...

Watch this Scientific Journal Video about Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System at JoVE.com

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System

Here, we present a method for screening anti-hepatitis B viral agents that inhibit the HBx-DDB1 interaction using a split luciferase assay system. This system allows easy detection of protein-protein interactions and is suitable for identifying inhibitors of such interactions.

There is an urgent need for novel therapeutic agents for hepatitis B virus (HBV) infection. Although currently available nucleos(t)ide analogs potently ...

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6.6K Views.  The University of Tokyo. Here, we present a method for screening anti-hepatitis B viral agents that inhibit the HBx-DDB1 interaction using a split luciferase assay system. This system allows easy detection of protein-protein interactions and is suitable for identifying inhibitors of such interactions.

Video: Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System

Experimental Generation of Carcinoma-Associated Fibroblasts (CAFs) from Human Mammary Fibroblasts

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of extracellular matrix (ECM) and a variety of mesenchymal cells, including fibroblasts, myofibroblasts, endothelial cells, pericytes and leukocytes 1-3.
The tumour-associated stroma is responsive to substantial paracrine signals released by neighbouring carcinoma cells. During the disease process, the stroma often becomes populated by carcinoma-associated fibroblasts (CAFs) including large numbers of myofibroblasts. These cells have previously been extracted from many different types of human carcinomas for their in vitro culture. A subpopulation of CAFs is distinguishable through their up-regulation of &alpha;-smooth muscle actin (&alpha;-SMA) expression4,5. These cells are a hallmark of 'activated fibroblasts' that share similar properties with myofibroblasts commonly observed in injured and fibrotic tissues 6. The presence of this myofibroblastic CAF subset is highly related to high-grade malignancies and associated with poor prognoses in patients.
Many laboratories, including our own, have shown that CAFs, when injected with carcinoma cells into immunodeficient mice, are capable of substantially promoting tumourigenesis 7-10. CAFs prepared from carcinoma patients, however, frequently undergo senescence during propagation in culture limiting the extensiveness of their use throughout ongoing experimentation. To overcome this difficulty, we developed a novel technique to experimentally generate immortalised human mammary CAF cell lines (exp-CAFs) from human mammary fibroblasts, using a coimplantation breast tumour xenograft model.
In order to generate exp-CAFs, parental human mammary fibroblasts, obtained from the reduction mammoplasty tissue, were first immortalised with hTERT, the catalytic subunit of the telomerase holoenzyme, and engineered to express GFP and a puromycin resistance gene. These cells were coimplanted with MCF-7 human breast carcinoma cells expressing an activated ras oncogene (MCF-7-ras cells) into a mouse xenograft. After a period of incubation in vivo, the initially injected human mammary fibroblasts were extracted from the tumour xenografts on the basis of their puromycin resistance 11.
We observed that the resident human mammary fibroblasts have differentiated, adopting a myofibroblastic phenotype and acquired tumour-promoting properties during the course of tumour progression. Importantly, these cells, defined as exp-CAFs, closely mimic the tumour-promoting myofibroblastic phenotype of CAFs isolated from breast carcinomas dissected from patients. Our tumour xenograft-derived exp-CAFs therefore provide an effective model to study the biology of CAFs in human breast carcinomas. The described protocol may also be extended for generating and characterising various CAF populations derived from other types of human carcinomas.

Experimental Generation of Carcinoma-Associated Fibroblasts CAFs from Human Mammary Fibroblasts

Carcinoma-associated fibroblasts (CAFs) rich in myofibroblasts present within the tumour stroma, play a major role in driving tumour progression. We developed a coimplantation tumour xengraft model for experimentally generating CAFs from human mammary fibroblasts. The protocol describes how to establish CAF myofibroblasts that acquire an ability to promote tumourigenesis.

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of ...

Use of Animal Model of Sepsis to Evaluate Novel Herbal Therapies

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several techniques, including infusion of exogenous bacterial toxin (endotoxemia) or bacteria (bacteremia), as well as surgical perforation of the cecum by cecal ligation and puncture (CLP)1-3. CLP allows bacteria spillage and fecal contamination of the peritoneal cavity, mimicking the human clinical disease of perforated appendicitis or diverticulitis. The severity of sepsis, as reflected by the eventual mortality rates, can be controlled surgically by varying the size of the needle used for cecal puncture2. In animals, CLP induces similar, biphasic hemodynamic cardiovascular, metabolic, and immunological responses as observed during the clinical course of human sepsis3. Thus, the CLP model is considered as one of the most clinically relevant models for experimental sepsis1-3.
Various animal models have been used to elucidate the intricate mechanisms underlying the pathogenesis of experimental sepsis. The lethal consequence of sepsis is attributable partly to an excessive accumulation of early cytokines (such as TNF, IL-1 and IFN-&gamma;)4-6 and late proinflammatory mediators (e.g., HMGB1)7. Compared with early proinflammatory cytokines, late-acting mediators have a wider therapeutic window for clinical applications. For instance, delayed administration of HMGB1-neutralizing antibodies beginning 24 hours after CLP, still rescued mice from lethality8,9, establishing HMGB1 as a late mediator of lethal sepsis. The discovery of HMGB1 as a late-acting mediator has initiated a new field of investigation for the development of sepsis therapies using Traditional Chinese Herbal Medicine. In this paper, we describe a procedure of CLP-induced sepsis, and its usage in screening herbal medicine for HMGB1-targeting therapies.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection, and can be simulated by a surgical technique termed cecal ligation and puncture (CLP). Here we describe a method to use CLP-induced animal model to screen medicinal herbs for therapeutic agents.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several ...

Intraoperative Detection of Subtle Endometriosis: A Novel Paradigm for Detection and Treatment of Pelvic Pain Associated with the Loss of Peritoneal Integrity

Endometriosis is a common disease affecting 40 to 70% of reproductive-aged women with chronic pelvic pain (CPP) and/or infertility. The purpose of this study was to demonstrate the use of a blue dye (methylene blue) to stain peritoneal surfaces during laparoscopy (L/S) to detect the loss of peritoneal integrity in patients with pelvic pain and suspected endometriosis. Forty women with CPP and 5 women without pain were evaluated in this pilot study. During L/S, concentrated dye was sprayed onto peritoneal surfaces, then aspirated and rinsed with Lactated Ringers solution. Areas of localized dye uptake were evaluated for the presence of visible endometriotic lesions. Areas of intense peritoneal staining were resected and some fixed in 2.5% buffered gluteraldehyde and examined by scanning (SEM) electron microscopy. Blue dye uptake was more common in women with endometriosis and chronic pelvic pain than controls (85% vs. 40%). Resection of the blue stained areas revealed endometriosis by SEM and loss of peritoneal cell-cell contact compared to normal, non-staining peritoneum. Affected peritoneum was associated with visible endometriotic implants in most but not all patients. Subjective pain relief was reported in 80% of subjects. Based on scanning electron microscopy, we conclude that endometrial cells extend well beyond visible implants of endometriosis and appear to disrupt the underlying mesothelium. Subtle lesions of endometriosis could therefore cause pelvic pain by disruption of peritoneal integrity, allowing menstrual or ovulatory blood and associated pain factors access to underlying sensory nerves. Complete resection of affected peritoneum may provide a better long-term treatment for endometriosis and CPP. This simple technique appears to improve detection of subtle or near invisible endometriosis in women with CPP and minimal visual findings at L/S and may serve to elevate diagnostic accuracy for endometriosis at laparoscopy.

Loss of peritoneal integrity provides a new paradigm to understand and treat chronic pelvic pain in women with mild forms of endometriosis and can be easily detected using intraoperative instillation of dye at the time of laparoscopy.

Endometriosis is a  common disease affecting 40 to 70% of reproductive-aged women with chronic  pelvic pain (CPP) and/or infertility. The purpose of this ...

Three-dimensional Co-culture Model for Tumor-stromal Interaction

Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal cells. The tumor microenvironment is comprised of a variety of cell types, such as fibroblasts, immune cells, vascular endothelial cells, pericytes and bone-marrow-derived cells, embedded in the extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) have a pro-tumorigenic role through the secretion of soluble factors, angiogenesis and ECM remodeling. The experimental models for cancer cell survival, proliferation, migration, and invasion have mostly relied on two-dimensional monocellular and monolayer tissue cultures or Boyden chamber assays. However, these experiments do not precisely reflect the physiological or pathological conditions in a diseased organ. To gain a better understanding of tumor stromal or tumor matrix interactions, multicellular and three-dimensional cultures provide more powerful tools for investigating intercellular communication and ECM-dependent modulation of cancer cell behavior. As a platform for this type of study, we present an experimental model in which cancer cells are cultured on collagen gels embedded with primary cultures of CAFs.

Here we present a protocol to co-culture in three-dimensions, which is useful for investigating multicellular interactions and extracellular matrix-dependent modulation of cancer cell behavior. In this experimental model, cancer cells are cultured on collagen gels embedded with human cancer-associated fibroblasts.

Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal ...

Three-Dimensional (3D) Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in particular (e.g., brain tumors such as glioblastoma multiforme and squamous cell carcinoma of the head and neck &#8211; SCCHN) it is a cause of severe morbidity and can be life-threatening even in the absence of distant metastases. In addition, cancers which have relapsed following treatment unfortunately often present with a more aggressive phenotype. Therefore, there is an opportunity to target the process of invasion to provide novel therapies that could be complementary to standard anti-proliferative agents. Until now, this strategy has been hampered by the lack of robust, reproducible assays suitable for a detailed analysis of invasion and for drug screening. Here we provide a simple micro-plate method (based on uniform, self-assembling 3D tumor spheroids) which has great potential for such studies. We exemplify the assay platform using a human glioblastoma cell line and also an SCCHN model where the development of resistance against targeted epidermal growth factor receptor (EGFR) inhibitors is associated with enhanced matrix-invasive potential. We also provide two alternative methods of semi-automated quantification: one using an imaging cytometer and a second which simply requires standard microscopy and image capture with digital image analysis.

Three-Dimensional 3D Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is a defining characteristic of malignant tumors. We provide here a simple, semi-automated micro-plate assay of invasion into a natural 3D biomatrix that has been exemplified with a number of models of advanced human cancers.

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in ...

Utilization of the Soft Agar Colony Formation Assay to Identify Inhibitors of Tumorigenicity in Breast Cancer Cells

Given the inherent difficulties in investigating the mechanisms of tumor progression in vivo, cell-based assays such as the soft agar colony formation assay (hereafter called soft agar assay), which measures the ability of cells to proliferate in semi-solid matrices, remain a hallmark of cancer research. A key advantage of this technique over conventional 2D monolayer or 3D spheroid cell culture assays is the close mimicry of the 3D cellular environment to that seen in vivo. Importantly, the soft agar assay also provides an ideal tool to rigorously test the effects of novel compounds or treatment conditions on cell proliferation and migration. Additionally, this assay enables the quantitative assessment of cell transformation potential within the context of genetic perturbations. We recently identified peptidylarginine deiminase 2 (PADI2) as a potential breast cancer biomarker and therapeutic target. Here we highlight the utility of the soft agar assay for preclinical anti-cancer studies by testing the effects of the PADI inhibitor, BB-Cl-amidine (BB-CLA), on the tumorigenicity of human ductal carcinoma in situ (MCF10DCIS) cells.

Here, we document the use of the soft agar colony formation assay to test the effects of a peptidylarginine deiminase (PADI) enzyme inhibitor, BB-Cl-amidine, on breast cancer tumorigenicity in vitro.

Given the inherent difficulties in investigating the mechanisms of tumor progression in vivo, cell-based assays such as the soft agar colony formation ...

Drug Repurposing Hypothesis Generation Using the "RE:fine Drugs" System

The promise of drug repurposing is that existing drugs may be used for new disease indications in order to curb the high costs and time for approval. The goal of computational methods for drug repurposing is to enable solutions for safer, cheaper and faster drug discovery. Towards this end, we developed a novel method that integrates genetic and clinical phenotype data from large-scale GWAS and PheWAS studies with detailed drug information on the concept of transitive Drug-Gene-Disease triads. We created "RE:fine Drugs," a freely available, interactive dashboard that automates gene, disease and drug-based searches to identify drug repurposing candidates. This web-based tool supports a user-friendly interface that includes an array of advanced search and export options. Results can be prioritized in a variety of ways, including but not limited to, biomedical literature support, strength and statistical significance of GWAS and/or PheWAS associations, disease indications and molecular drug targets. Here we provide a protocol that illustrates the functionalities available in the "RE:fine Drugs" system and explores the different advanced options through a case study.

Here we describe a protocol using the web-based drug repurposing hypothesis generation tool: "RE:fine Drugs." This protocol can be modified to a user's preferences at the level of the query type (gene, drug or disease) and/or the range of available advanced options.

The promise of drug repurposing is that existing drugs may be used for new disease indications in order to curb the high costs and time for approval. The ...

Using Retinal Imaging to Study Dementia

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central nervous system (CNS) and shares prominent similarities with the brain in terms of embryological origin, anatomical features and physiological properties.&#160; The vascular and neuronal structure in the retina can now be visualized easily and non-invasively using retinal imaging techniques, including fundus photography and optical coherence tomography (OCT), and quantified semi-automatically using computer-assisted analysis programs. Studying the associations between vascular and neuronal changes in the retina and dementia could improve our understanding of dementia and, potentially, aid in diagnosis and risk assessment.&#160; This protocol aims to describe a method of quantifying and analyzing retinal vasculature and neuronal structure, which are potentially associated with dementia. This protocol also provides examples of retinal changes in subjects with dementia, and discusses technical issues and current limitations of retinal imaging.

The retina shares prominent similarities with the brain and thus represents a unique window to study vasculature and neuronal structure in the brain non-invasively. This protocol describes a method to study dementia using retinal imaging techniques. This method can potentially aid in diagnosis and risk assessment of dementia.

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central ...

Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans

Coronary artery calcification (CAC) provides an objective measure of coronary artery disease and can readily be identified on non-gated computed tomography (CT) scans with a high correlation with gated cardiac CT scans. This standardized protocol takes a step-wise approach to not only optimizing an image for the identification of calcification but also to distinguishing CAC from other common causes of calcification in the cardiac silhouette. Recognition of CAC on non-gated CT scans helps to identify a very powerful prognostic factor that can influence therapeutic interventions or downstream diagnostic testing without requiring a gated cardiac scan. These non-gated CT scans are often acquired as part of the routine care of the patient, and this data is readily available without another dose of&#160;ionizing radiation. This protocol allows for the precise and accurate extraction of this data for the purposes of retrospective data analysis in clinical research studies, but also in the clinical evaluation and management of patients.

Here, we present a protocol to reliably and systematically identify coronary artery calcification (CAC) on non-gated computed tomography (CT) scans of the chest or abdomen. CAC provides an objective measure of coronary artery disease for both research and clinical purposes.

Coronary artery calcification (CAC) provides an objective measure of coronary artery disease and can readily be identified on non-gated computed ...

Visualization of Endogenous Mitophagy Complexes In Situ in Human Pancreatic Beta Cells Utilizing Proximity Ligation Assay

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated insulin release. Assessment of mitophagy is challenging and often requires genetic reporters or multiple complementary techniques not easily utilized in tissue samples, such as primary human pancreatic islets. Here we demonstrate a robust approach to visualize and quantify formation of key endogenous mitophagy complexes in primary human pancreatic islets. Utilizing the sensitive proximity ligation assay technique to detect interaction of the mitophagy regulators NRDP1 and USP8, we are able to specifically quantify formation of essential mitophagy complexes in situ. By coupling this approach to counterstaining for the transcription factor PDX1, we can quantify mitophagy complexes, and the factors that can impair mitophagy, specifically within beta cells. The methodology we describe overcomes the need for large quantities of cellular extracts required for other protein-protein interaction studies, such as immunoprecipitation (IP) or mass spectrometry, and is ideal for precious human islet&#160;samples generally not available in sufficient quantities for these approaches. Further, this methodology obviates the need for flow sorting techniques to purify beta cells from a heterogeneous islet population for downstream protein applications. Thus, we describe a valuable protocol for visualization of mitophagy highly compatible for use in heterogeneous and limited cell populations.

This protocol outlines a method for quantitative analysis of mitophagy protein complex formation specifically in beta cells from primary human islet samples. This technique thus allows analysis of mitophagy from limited biological material, which are crucial in precious human pancreatic beta cell samples.

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated ...