Name: screening assays to characterize novel endothelial regulators involved in the inflammatory response
Uploaded: 2017-09-15T13:00:00
Description: Watch this Scientific Journal Video about Screening Assays to Characterize Novel Endothelial Regulators Involved in the Inflammatory Response at JoVE.com

This work was supported by the Ministerio de Econom&#237;a y Competitividad (MINECO) and the Instituto de Salud Carlos III (ISCIII) (grant number IERPY 1149/16 to A.L.; MPY 1410/09 to S. Hortelano); by the MINECO through the Fondo de Investigaci&#243;n en Salud (FIS) (grants numbers PI11.0036 and PI14.0055 to S. Hortelano). S. Herranz was supported by IERPY 1149/16 from ISCIII.

1. Endothelial Cell Culture
<ol>
	<li>Tissue culture treated plates
	<ol>
		<li>Coat 100 mm tissue culture plates with 2.5 mL gelatin solution (autoclaved, 0.1% gelatin in distilled water) for 30 min at 37 &#176;C; this can be extrapolated to the required well format. Aspirate the gelatin solution and leave plates to air-dry in the tissue culture hood.</li>
	</ol>
	</li>
	<li>Tissue culture conditions
	<ol>
		<li>Cultivate the MLEC-04 cells inside a biological incubator (37 &#176;C, 95...

<ol>
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This endothelial protocol describes a stepwise technology that establishes the groundwork for exploring novel mechanisms involved in the regulation of the inflammatory response. These approaches are based on the study of the endothelial activity stimulated by LPS and evaluate the critical steps involved in leukocyte recruitment during the inflammatory response, specifically: endothelial cytokines release, endothelial adhesion molecules expression and leukocyte adhesion to the vascular layer. Once the endothelial paramete...

Inflammation is a beneficial biological response against infectious agents, with the major aim to eliminate the pathogen and repair damaged tissue. Under certain conditions, such as chronic infections or autoimmune diseases, inflammation does not resolve. Instead, there is an aberrant reaction with continuous infiltration of leukocytes, resulting in a prolonged immune response that leads to tissue damage, fibrosis, loss of function, and overall, disability and in some cases death of the patient. These human disorders, cataloged as inflammatory diseases, all involve the blood vessels for the control of leukocyte extravasation1,2.
The endothelial cells play a fundamental role in the regulation of the inflammatory response by controlling leukocyte trafficking. When the endothelial layer is exposed to inflammatory mediators such as LPS, the resting endothelium activates and expresses pro-inflammatory cytokines (Cxcl10, Cxcl5, Cxcl1, etc.) and adhesion molecules (E-selectin, VCAM-1 and ICAM-1) that favor recruitment of circulating leukocytes to the infection site. The leukocytes primed by the released cytokines then mediate rolling and interaction with the endothelial layer through the correspondent adhesive counterparts: PSGL-1 to selectin, &#945;4&#946;1 integrin to VCAM-1, and &#945;L&#946;2 integrin to ICAM-1. Finally, the leukocytes migrate across the vasculature towards the focus of inflammation3.
The essential role of the endothelium in regulating the inflammatory response has been demonstrated on mice that were genetically modified to express the LPS receptor, toll-like receptor 4 (TLR4), only on the endothelial cells. These endothelial-TLR4 animals were able to respond to an LPS-mediated inflammation and to detect the infection generated after bacteria inoculation, and consequently achieve infection resolution and survival at similar levels as the wild type mice4,5.
For the endothelium-regulated inflammatory response pathway, it has been postulated that the inhibition at some stages of the leukocyte-endothelium interaction would result in the reduction of trans-endothelial migration and a better prognosis for inflammatory-related diseases. In fact, several strategies targeting the endothelial activation and leukocyte-endothelium interaction have been designed to hinder extravasation of immune cells as a treatment for inflammatory disorders6,7.
In this report, we describe a thorough group of in vitro techniques to fully characterize the endothelial activity in response to the inflammatory stimulus LPS and its role in leukocyte activation and adhesion to the vascular layer. The endothelial cell model used in this manuscript was the mouse lung endothelial cell line (MLEC-04), as described by Hortelano et al.8. The MLEC-04 cell line has been validated in the literature to be an appropriate system to study endothelial activation9,10. Based on research interests, these approaches can be easily extrapolated to any endothelial or leukocyte systems and inflammatory profile. Once the endothelial parameters in the selected conditions are defined, the system can test novel drugs on the proposed experimentation to evaluate the vascular activation. In this inflammatory context, the endothelium cells tested with the compound of interest can be compared to the control conditions of the cells, and any resulting differences may inform the drug&#39;s prognostic outcome on development and progression of inflammation. To conclude, we propose a relevant system to characterize new drug targets to the endothelial cells, which can influence the design of novel vascular-specific therapies against inflammatory-related diseases.

<table border="0" cellpadding="0" cellspacing="0" width="820">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Gelatin</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:116px;">G9391</td>
			<td style="width:256px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM-F12</td>
			<td>Lonza</td>
			<td>BE12-719F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal Bovine Serum</td>
			<td>Sigma</td>
			<td>A4503</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin streptomycin</td>
			<td>Lonza</td>
			<td>DE17-602E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsine</td>
			<td>Lonza</td>
			<td>BE17-160E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA</td>
			<td>Sigma</td>
			<td>ED2SS</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LPS</td>
			<td>Sigma</td>
			<td>L2880</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trizol</td>
			<td>Sigma</td>
			<td>T9424</td>
			<td>RNA extraction buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Isopropanol</td>
			<td>Sigma</td>
			<td>33539</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethanol absoluto</td>
			<td>Panreac</td>
			<td>1,310,861,612</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Pure H2O</td>
			<td>Qiagen</td>
			<td>1017979</td>
			<td>RNAse free</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agarose</td>
			<td>Pronadisa</td>
			<td>8020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stain for agarose gels</td>
			<td>Invitrogen</td>
			<td>s33102</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SuperScript III First-Strand Synth</td>
			<td>Invitrogen</td>
			<td height="21" style="height:21px;width:116px;">18080051</td>
			<td>Reagents for RT-PCR</td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Fast SYBR Green Master Mix</td>
			<td>Applied Biosystems</td>
			<td align="left">4385610</td>
			<td>Fluorescent stain for qPCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MicroAmp Fast Optical 96-Well</td>
			<td>Applied Biosystems</td>
			<td>4346906</td>
			<td>Plates for qPCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">U-bottom 96 well plates</td>
			<td>Falcon</td>
			<td>353072</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytometry tubes</td>
			<td>Falcon</td>
			<td>352054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TX100</td>
			<td>Panreac</td>
			<td>212314</td>
			<td>Non-ionic surfactant</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris-HCl</td>
			<td>Panreac</td>
			<td>1,319,401,211</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride</td>
			<td>Merck</td>
			<td>1,064,041,000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium pyrophosphate</td>
			<td>Sigma</td>
			<td>221368</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium fluoride</td>
			<td>Sigma</td>
			<td>S7920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium orthovanadate</td>
			<td>sigma</td>
			<td>13721-39-6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protease inhibitor cocktail</td>
			<td>sigma</td>
			<td>P8340</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Pierce BCA Protein Assay Kit</td>
			<td>Pierce</td>
			<td>23225</td>
			<td>Reagents for bicinchoninic acid assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#946;-mercaptoethanol</td>
			<td>merck</td>
			<td align="left">805,740</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">PVDF Transfer Membrane, 0.45 &#181;m</td>
			<td>Thermo Scientific</td>
			<td>88518</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tween-20</td>
			<td>Panreac</td>
			<td align="left">1,623,121,611</td>
			<td>Polysorbate 20</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS</td>
			<td>Lonza</td>
			<td>BE17-515Q</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ECL</td>
			<td>Millipore</td>
			<td>WBKLS0500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fibronectin</td>
			<td>Sigma</td>
			<td>F1141</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Laminin</td>
			<td>Sigma</td>
			<td>L2020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Collagen type I</td>
			<td>Sigma</td>
			<td>c8919</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acetic acid</td>
			<td>Panreac</td>
			<td>1,310,081,611</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan blue</td>
			<td>Sigma</td>
			<td>T8154</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Paraformaldehyde</td>
			<td>Sigma</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methanol</td>
			<td>Panreac</td>
			<td>1,310,911,612</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Crystal violet</td>
			<td>Sigma</td>
			<td>HT90132</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium citrate</td>
			<td>Sigma</td>
			<td>C7254</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethanol 96%</td>
			<td>Panreac</td>
			<td>1,410,851,212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CFSE</td>
			<td>Sigma</td>
			<td>21888</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RPMI</td>
			<td>Lonza</td>
			<td>BE12-115F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SDS</td>
			<td>Bio-Rad</td>
			<td>161-0418</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Infinite M200</td>
			<td>Tecan</td>
			<td>M200</td>
			<td>Multi mode microplate reader</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gel Doc 2000</td>
			<td>Bio-Rad</td>
			<td>2000</td>
			<td>Gel documentation system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">StepOnePlus</td>
			<td>Applied Biosystems</td>
			<td>StepOnePlus</td>
			<td>qPCR system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MACSQuant Analyzer 10</td>
			<td>Miltenyi Biotec</td>
			<td>Analyzer 10</td>
			<td>Cytometry equipment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ChemiDoc MP</td>
			<td>Bio-Rad</td>
			<td>MP</td>
			<td>Chemiluminescence detection system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antibodies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">PECAM-1</td>
			<td>BD Biosciences</td>
			<td>553370</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">ICAM-2</td>
			<td>Biolegend</td>
			<td>1054602</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">E-selectin</td>
			<td>BD Biosciences</td>
			<td>553749</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">VCAM-1</td>
			<td>BD Biosciences</td>
			<td>553330</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">ICAM-1</td>
			<td>Becton Dickinson</td>
			<td>553250</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-rat IgG-FITC</td>
			<td>Jackson Immuno Research</td>
			<td>112-095-006</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti armenian hamster-FITC</td>
			<td>Jackson Immuno Research</td>
			<td>127-095-160</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rat IgG isotyope control</td>
			<td>Invitrogen</td>
			<td style="width:116px;">10700</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Armenian hamster IgG isotype control</td>
			<td>Invitrogen</td>
			<td>PA5-33220</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">P-I&#954;&#914;-&#945;</td>
			<td>Cell Signaling</td>
			<td>2859</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#946;-Actin</td>
			<td>Sigma</td>
			<td>A5441</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">P-ERK</td>
			<td>Cell Signaling</td>
			<td>9101</td>
			<td>Use at 10 &#181;g/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-mouse HRP</td>
			<td>GE Healthcare</td>
			<td>LNXA931/AE</td>
			<td>Use at 1:10000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-rabbit HRP</td>
			<td>GE Healthcare</td>
			<td>LNA934V/AG</td>
			<td>Use at 1:10000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-rat HRP</td>
			<td>Santa Cruz</td>
			<td>Sc-3823</td>
			<td>Use at 1:10000</td>
		</tr>
	</tbody>
</table>

screening assays to characterize novel endothelial regulators involved in the inflammatory response

The endothelial layer is essential for maintaining homeostasis in the body by controlling many different functions. Regulation of the inflammatory response by the endothelial layer is crucial to efficiently fight against harmful inputs and aid in the recovery of damaged areas. When the endothelial cells are exposed to an inflammatory environment, such as the outer component of gram-negative bacteria membrane, lipopolysaccharide (LPS), they express soluble pro-inflammatory cytokines, such as Ccl5, Cxcl1 and Cxcl10, and trigger the activation of circulating leukocytes. In addition, the expression of adhesion molecules E-selectin, VCAM-1 and ICAM-1 on the endothelial surface enables the interaction and adhesion of the activated leukocytes to the endothelial layer, and eventually the extravasation towards the inflamed tissue. In this scenario, the endothelial function must be tightly regulated because excessive or defective activation in the leukocyte recruitment could lead to inflammatory-related disorders. Since many of these disorders do not have an effective treatment, novel strategies with a focus on the vascular layer must be investigated. We propose comprehensive assays that are useful to the search of novel endothelial regulators that modify leukocyte function. We analyze endothelial activation by using specific expression targets involved in leukocyte recruitment (such as, cytokines, chemokines, and adhesion molecules) with several techniques, including: real-time quantitative polymerase chain reaction (RT-qPCR), western-blot, flow cytometry and adhesion assays. These approaches determine endothelial function in the inflammatory context and are very useful to perform screening assays to characterize novel endothelial inflammatory regulators that are potentially valuable for designing new therapeutic strategies.

Evaluation of LPS-induced endothelial cell activation by RT-qPCR
The serum starved MLEC-04 cells were stimulated by 100 ng/mL of LPS for 6 h, and the endothelial gene expression was assessed using RT-qPCR by comparing the expression of activation markers to the resting condition. As shown in Figure 1A, the LPS-incubated MLEC-04 cells induced the mRNA expression of selected adhesion molecules involved i...

Watch this Scientific Journal Video about Screening Assays to Characterize Novel Endothelial Regulators Involved in the Inflammatory Response at JoVE.com

Screening Assays to Characterize Novel Endothelial Regulators Involved in the Inflammatory Response

Vascular endothelium tightly controls leukocyte recruitment. Inadequate leukocyte extravasation contributes to human inflammatory diseases. Therefore, searching for novel regulatory elements of endothelial activation is necessary to design improved therapies for inflammatory disorders. Here, we describe a comprehensive methodology to characterize novel endothelial regulators that can modify leukocyte trafficking during inflammation.

The endothelial layer is essential for maintaining homeostasis in the body by controlling many different functions. Regulation of the inflammatory ...

The overall goal of this screening assay is to characterize novel endothelial regulators involved in the inflammatory response of interest for designing new therapeutic strategies against inflammatory disorders.This method can help answer key questions in the pathology field such as defining novel endothelial-targeting drugs able to attenuate inflammatory-related diseases.The main advantage of this endothelial protocol is that describes assay technology that establishes the basis for exploring novel mechanisms involved in the regulation of the inflammatory response.Demonstrating this methodology will be Maria Angeles Higueras, a post-doc from our lab and Sandra Herranz, a technician from our lab.To begin, culture MLEC-04 cells in complete DMEM F12 medium supplemented with 10%FBS and Pen-Strep.Incubate the cells in a biological incubator at 37

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Research

JoVE Journal

Immunology and Infection

RNAi Screening for Host Factors Involved in Vaccinia Virus Infection using Drosophila Cells

Viral pathogens represent a significant public health threat; not only can viruses cause natural epidemics of human disease, but their potential use in bioterrorism is also a concern. A better understanding of the cellular factors that impact infection would facilitate the development of much-needed therapeutics. Recent advances in RNA interference (RNAi) technology coupled with complete genome sequencing of several organisms has led to the optimization of genome-wide, cell-based loss-of-function screens. Drosophila cells are particularly amenable to genome-scale screens because of the ease and efficiency of RNAi in this system 1. Importantly, a wide variety of viruses can infect Drosophila cells, including a number of mammalian viruses of medical and agricultural importance 2,3,4. Previous RNAi screens in Drosophila have identified host factors that are required for various steps in virus infection including entry, translation and RNA replication 5. Moreover, many of the cellular factors required for viral replication in Drosophila cell culture are also limiting in human cells infected with these viruses 4,6,7,8, 9. Therefore, the identification of host factors co-opted during viral infection presents novel targets for antiviral therapeutics. Here we present a generalized protocol for a high-throughput RNAi screen to identify cellular factors involved in viral infection, using vaccinia virus as an example.

RNAi Screening for Host Factors Involved in Vaccinia Virus Infection using Drosophila Cells

Novel host factors involved in viral infection can be identified through cell-based genome-wide loss of function RNAi screening. A Drosophila cell culture model is particularly amenable to this approach due to the ease and efficiency of RNAi. Here we demonstrate this technique using vaccinia virus as an example.

Viral pathogens represent a significant public health threat; not only can viruses cause natural epidemics of human disease, but their potential use in ...

An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response

Most known parasitoid wasp species attack the larval or pupal stages of Drosophila. While Trichopria drosophilae infect the pupal stages of the host (Fig. 1A-C), females of the genus Leptopilina (Fig. 1D, 1F, 1G) and Ganaspis (Fig. 1E) attack the larval stages. We use these parasites to study the molecular basis of a biological arms race. Parasitic wasps have tremendous value as biocontrol agents. Most of them carry virulence and other factors that modify host physiology and immunity. Analysis of Drosophila wasps is providing insights into how species-specific interactions shape the genetic structures of natural communities. These studies also serve as a model for understanding the hosts' immune physiology and how coordinated immune reactions are thwarted by this class of parasites.
The larval/pupal cuticle serves as the first line of defense. The wasp ovipositor is a sharp needle-like structure that efficiently delivers eggs into the host hemocoel. Oviposition is followed by a wound healing reaction at the cuticle (Fig. 1C, arrowheads). Some wasps can insert two or more eggs into the same host, although the development of only one egg succeeds. Supernumerary eggs or developing larvae are eliminated by a process that is not yet understood. These wasps are therefore referred to as solitary parasitoids.
Depending on the fly strain and the wasp species, the wasp egg has one of two fates. It is either encapsulated, so that its development is blocked (host emerges; Fig. 2 left); or the wasp egg hatches, develops, molts, and grows into an adult (wasp emerges; Fig. 2 right). L. heterotoma is one of the best-studied species of Drosophila parasitic wasps. It is a "generalist," which means that it can utilize most Drosophila species as hosts1. L. heterotoma and L. victoriae are sister species and they produce virus-like particles that actively interfere with the encapsulation response2. Unlike L. heterotoma, L. boulardi is a specialist parasite and the range of Drosophila species it utilizes is relatively limited1. Strains of L. boulardi also produce virus-like particles3 although they differ significantly in their ability to succeed on D. melanogaster1. Some of these L. boulardi strains are difficult to grow on D. melanogaster1 as the fly host frequently succeeds in encapsulating their eggs. Thus, it is important to have the knowledge of both partners in specific experimental protocols.
In addition to barrier tissues (cuticle, gut and trachea), Drosophila larvae have systemic cellular and humoral immune responses that arise from functions of blood cells and the fat body, respectively. Oviposition by L. boulardi activates both immune arms1,4. Blood cells are found in circulation, in sessile populations under the segmented cuticle, and in the lymph gland. The lymph gland is a small hematopoietic organ on the dorsal side of the larva. Clusters of hematopoietic cells, called lobes, are arranged segmentally in pairs along the dorsal vessel that runs along the anterior-posterior axis of the animal (Fig. 3A). The fat body is a large multifunctional organ (Fig. 3B). It secretes antimicrobial peptides in response to microbial and metazoan infections.
Wasp infection activates immune signaling (Fig. 4)4. At the cellular level, it triggers division and differentiation of blood cells. In self defense, aggregates and capsules develop in the hemocoel of infected animals (Fig. 5)5,6. Activated blood cells migrate toward the wasp egg (or wasp larva) and begin to form a capsule around it (Fig. 5A-F). Some blood cells aggregate to form nodules (Fig. 5G-H). Careful analysis reveals that wasp infection induces the anterior-most lymph gland lobes to disperse at their peripheries (Fig. 6C, D).
We present representative data with Toll signal transduction pathway components Dorsal and Sp&auml;tzle (Figs. 4,5,7), and its target Drosomycin (Fig. 6), to illustrate how specific changes in the lymph gland and hemocoel can be studied after wasp infection. The dissection protocols described here also yield the wasp eggs (or developing stages of wasps) from the host hemolymph (Fig. 8).

An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response

Parasitoid (parasitic) wasps constitute a major class of natural enemies of many insects including Drosophila melanogaster. We will introduce the techniques to propagate these parasites in Drosophila spp. and demonstrate how to analyze their effects on immune tissues of Drosophila larvae.

Most known parasitoid wasp species attack the larval or pupal stages of Drosophila. While Trichopria drosophilae infect the pupal stages of the host (Fig. ...

Use of Interferon-&gamma; Enzyme-linked Immunospot Assay to Characterize Novel T-cell Epitopes of Human Papillomavirus

A protocol has been developed to overcome the difficulties of isolating and characterizing rare T cells specific for pathogens, such as human papillomavirus (HPV), that cause localized infections. The steps involved are identifying region(s) of HPV proteins that contain T-cell epitope(s) from a subject, selecting for the peptide-specific T cells based on interferon-&gamma; (IFN-&gamma;) secretion, and growing and characterizing the T-cell clones (Fig. 1). Subject 1 was a patient who was recently diagnosed with a high-grade squamous intraepithelial lesion by biopsy and underwent loop electrical excision procedure for treatment on the day the T cells were collected1. A region within the human papillomavirus type 16 (HPV 16) E6 and E7 proteins which contained a T-cell epitope was identified using an IFN- g enzyme-linked immunospot (ELISPOT) assay performed with overlapping synthetic peptides (Fig. 2). The data from this assay were used not only to identify a region containing a T-cell epitope, but also to estimate the number of epitope specific T cells and to isolate them on the basis of IFN- &gamma; secretion using commercially available magnetic beads (CD8 T-cell isolation kit, Miltenyi Biotec, Auburn CA). The selected IFN-&gamma; secreting T cells were diluted and grown singly in the presence of an irradiated feeder cell mixture in order to support the growth of a single T-cell per well. These T-cell clones were screened using an IFN- &gamma; ELISPOT assay in the presence of peptides covering the identified region and autologous Epstein-Barr virus transformed B-lymphoblastoid cells (LCLs, obtained how described by Walls and Crawford)2 in order to minimize the number of T-cell clone cells needed. Instead of using 1 x 105 cells per well typically used in ELISPOT assays1,3, 1,000 T-cell clone cells in the presence of 1 x 105 autologous LCLs were used, dramatically reducing the number of T-cell clone cells needed. The autologous LCLs served not only to present peptide antigens to the T-cell clone cells, but also to keep a high cell density in the wells allowing the epitope-specific T-cell clone cells to secrete IFN-&gamma;. This assures successful performance of IFN-&gamma; ELISPOT assay. Similarly, IFN- &gamma; ELISPOT assays were utilized to characterize the minimal and optimal amino acid sequence of the CD8 T-cell epitope (HPV 16 E6 52-61 FAFRDLCIVY) and its HLA class I restriction element (B58). The IFN- &gamma; ELISPOT assay was also performed using autologous LCLs infected with vaccinia virus expressing HPV 16 E6 or E7 protein. The result demonstrated that the E6 T-cell epitope was endogenously processed. The cross-recognition of homologous T-cell epitope of other high-risk HPV types was shown. This method can also be used to describe CD4 T-cell epitopes4.

Use of Interferon-&amp;#947; Enzyme-linked Immunospot Assay to Characterize Novel T-cell Epitopes of Human Papillomavirus

Characterizing T-cell epitopes of pathogens that cause localized infections such as human papillomavirus is a challenge because of limited number of T cells in circulation. A method is described in which rare T cells were isolated and were characterized starting with a very small number of cells.

A protocol has been developed to overcome the difficulties of isolating and characterizing rare T cells specific for pathogens, such as human ...

Assays for the Identification of Novel Antivirals against Bluetongue Virus

To identify potential antivirals against BTV, we have developed, optimized and validated three assays presented here. The CPE-based assay was the first assay developed to evaluate whether a compound showed any antiviral efficacy and have been used to screen large compound library. Meanwhile, cytotoxicity of antivirals could also be evaluated using the CPE-based assay. The dose-response assay was designed to determine the range of efficacy for the selected antiviral, i.e. 50% inhibitory concentration (IC50) or effective concentration (EC50), as well as its range of cytotoxicity (CC50). The ToA assay was employed for the initial MoA study to determine the underlying mechanism of the novel antivirals during BTV viral lifecycle or the possible effect on host cellular machinery. These assays are vital for the evaluation of antiviral efficacy in cell culture system, and have been used for our recent researches leading to the identification of a number of novel antivirals against BTV.

Three assays, including the cytopathic effect (CPE)-based assay, dose-response assay and Time-of-Addition (ToA) assay have been developed, optimized, validated and utilized to identify novel antivirals against Bluetongue virus (BTV), as well as to determine the possible Mechanism-of-Action (MoA) for newly identified antivirals.

To identify potential antivirals against BTV, we have  developed, optimized and validated three assays presented here. The CPE-based  assay was the first ...

Novel Whole-tissue Quantitative Assay of Nitric Oxide Levels in Drosophila Neuroinflammatory Response

Neuroinflammation is a complex innate immune response vital to the healthy function of the central nervous system (CNS). Under normal conditions, an intricate network of inducers, detectors, and activators rapidly responds to neuron damage, infection or other immune infractions. This inflammation of immune cells is intimately associated with the pathology of neurodegenerative disorders, such as Parkinson&#39;s disease (PD), Alzheimer&#39;s disease and ALS. Under compromised disease states, chronic inflammation, intended to minimize neuron damage, may lead to an over-excitation of the immune cells, ultimately resulting in the exacerbation of disease progression. For example, loss of dopaminergic neurons in the midbrain, a hallmark of PD, is accelerated by the excessive activation of the inflammatory response. Though the cause of PD is largely unknown, exposure to environmental toxins has been implicated in the onset of sporadic cases. The herbicide paraquat, for example, has been shown to induce Parkinsonian-like pathology in several animal models, including Drosophila melanogaster. Here, we have used the conserved innate immune response in Drosophila to develop an assay capable of detecting varying levels of nitric oxide, a cell-signaling molecule critical to the activation of the inflammatory response cascade and targeted neuron death. Using paraquat-induced neuronal damage, we assess the impact of these immune insults on neuroinflammatory stimulation through the use of a novel, quantitative assay. Whole brains are fully extracted from flies either exposed to neurotoxins or of genotypes that elevate susceptibility to neurodegeneration then incubated in cell-culture media. Then, using the principles of the Griess reagent reaction, we are able to detect minor changes in the secretion of nitric oxide into cell-culture media, essentially creating a primary live-tissue model in a simple procedure. The utility of this model is amplified by the robust genetic and molecular complexity of Drosophila melanogaster, and this assay can be modified to be applicable to other Drosophila tissues or even other small, whole-organism inflammation models.

Novel Whole-tissue Quantitative Assay of Nitric Oxide Levels in Drosophila Neuroinflammatory Response

Levels of the inflammatory cell-signaling molecule nitric oxide (NO) are commonly assayed using Griess reagent. In this protocol, we have created a modified Griess assay utilizing live Drosophila brain tissue in order to detect the secretion of NO in a simple, quantifiable and highly repeatable method.

Neuroinflammation is a complex innate immune response vital to the healthy function of the central nervous system (CNS). Under normal conditions, an ...

VIGS-Mediated Forward Genetics Screening for Identification of Genes Involved in Nonhost Resistance

Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens. Virus-induced gene silencing (VIGS)-based forward genetics screening is a useful approach for identification of plant defense genes imparting nonhost resistance. Tobacco rattle virus (TRV)-based VIGS vector is the most efficient VIGS vector to date and has been efficiently used to silence endogenous target genes in Nicotiana benthamiana.

	In this manuscript, we demonstrate a forward genetics screening approach for silencing of individual clones from a cDNA library in N. benthamiana and assessing the response of gene silenced plants for compromised nonhost resistance against nonhost pathogens, Pseudomonas syringae pv. tomato T1, P. syringae pv. glycinea, and X. campestris pv. vesicatoria. These bacterial pathogens are engineered to express GFPuv protein and their green fluorescing colonies can be seen by naked eye under UV light in the nonhost pathogen inoculated plants if the silenced target gene is involved in imparting nonhost resistance. This facilitates reliable and faster identification of gene silenced plants susceptible to nonhost pathogens. Further, promising candidate gene information can be known by sequencing the plant gene insert in TRV vector. Here we demonstrate the high throughput capability of VIGS-mediated forward genetics to identify genes involved in nonhost resistance. Approximately, 100 cDNAs can be individually silenced in about two to three weeks and their relevance in nonhost resistance against several nonhost bacterial pathogens can be studied in a week thereafter. In this manuscript, we enumerate the detailed steps involved in this screening. VIGS-mediated forward genetics screening approach can be extended not only to identifying genes involved in nonhost resistance but also to studying genes imparting several biotic and abiotic stress tolerances in various plant species.

Virus-induced gene silencing is an useful tool for identifying genes involved in nonhost resistance of plants. We demonstrate the use of bacterial pathogens expressing GFPuv in identifying gene silenced plants susceptible to nonhost pathogens. This approach is easy, fast and facilitates large scale screening and similar protocol can be applied to studying various other plant-microbe interactions.


	Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important ...

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in mice. Recently, myeloid differentiation factor 88 (MyD88) signaling was shown to be important for initial T cell priming and memory T cell development during WNV NS4B-P38G mutant infection. In this study, two flow cytometry-based methods &#8211; an in vitro T cell priming assay and an intracellular cytokine staining (ICS) &#8211; were utilized to assess dendritic cells (DCs) and T cell functions. In the T cell priming assay, cell proliferation was analyzed by flow cytometry following co-culture of DCs from both groups of mice with carboxyfluorescein succinimidyl ester (CFSE) - labeled CD4+ T cells of OTII transgenic mice. This approach provided an accurate determination of the percentage of proliferating CD4+ T cells with significantly improved overall sensitivity than the traditional assays with radioactive reagents. A microcentrifuge tube system was used in both cell culture and cytokine staining procedures of the ICS protocol. Compared to the traditional tissue culture plate-based system, this modified procedure was easier to perform at biosafety level (BL) 3 facilities. Moreover, WNV- infected cells were treated with paraformaldehyde in both assays, which enabled further analysis outside BL3 facilities. Overall, these in vitro immunological assays can be used to efficiently assess cell-mediated immune responses during WNV infection.

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

Two flow cytometry-based methods &#8211; an in vitro T cell priming assay and intracellular cytokine staining were utilized to measure antigen presenting capacity of dendritic cells and antigen-specific T cell responses to a West Nile virus mutant infection in mice.

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in ...

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Current investigations into phage-host interactions are dependent on extrapolating knowledge from (meta)genomes. Interestingly, 60 - 95% of all phage sequences share no homology to current annotated proteins. As a result, a large proportion of phage genes are annotated as hypothetical. This reality heavily affects the annotation of both structural and auxiliary metabolic genes. Here we present phenomic methods designed to capture the physiological response(s) of a selected host during expression of one of these unknown phage genes. Multi-phenotype Assay Plates (MAPs) are used to monitor the diversity of host substrate utilization and subsequent biomass formation, while metabolomics provides bi-product analysis by monitoring metabolite abundance and diversity. Both tools are used simultaneously to provide a phenotypic profile associated with expression of a single putative phage open reading frame (ORF). Representative results for both methods are compared, highlighting the phenotypic profile differences of a host carrying either putative structural or metabolic phage genes. In addition, the visualization techniques and high throughput computational pipelines that facilitated experimental analysis are presented.

Here, we present phenomic approaches for the functional characterization of putative phage genes. Techniques include a developed assay capable of monitoring host anabolic metabolism, the Multi-phenotype Assay Plates (MAPs), in addition to the established method of metabolomics, capable of measuring effects to catabolic metabolism.

Current investigations into phage-host interactions are dependent on extrapolating knowledge from (meta)genomes. Interestingly, 60 - 95% of all phage ...

Biomimetic Materials to Characterize Bacteria-host Interactions

Bacterial attachment to host cells is one of the earliest events during bacterial colonization of host tissues and thus a key step during infection. The biochemical and functional characterization of adhesins mediating these initial bacteria-host interactions is often compromised by the presence of other bacterial factors, such as cell wall components or secreted molecules, which interfere with the analysis. This protocol describes the production and use of biomimetic materials, consisting of pure recombinant adhesins chemically coupled to commercially available, functionalized polystyrene beads, which have been used successfully to dissect the biochemical and functional interactions between individual bacterial adhesins and host cell receptors. Protocols for different coupling chemistries, allowing directional immobilization of recombinant adhesins on polymer scaffolds, and for assessment of the coupling efficiency of the resulting &#8220;bacteriomimetic&#8221; materials are also discussed. We further describe how these materials can be used as a tool to inhibit pathogen mediated cytotoxicity and discuss scope, limitations and further applications of this approach in studying bacterial - host interactions.

Bacterial attachment to host cells is a key step during host colonization and infection. This protocol describes the generation of polymer-coupled recombinant adhesins as biomimetic materials which allow analysis of the contribution of individual adhesins to these processes, independent of other bacterial factors.

Bacterial attachment to host cells is one of the earliest events during bacterial colonization of host tissues and thus a key step during infection. The ...

Microscopy-based Assays for High-throughput Screening of Host Factors Involved in Brucella Infection of Hela Cells

Brucella species are facultative intracellular pathogens that infect animals as their natural hosts. Transmission to humans is most commonly caused by direct contact with infected animals or by ingestion of contaminated food and can lead to severe chronic infections.
Brucella can invade professional and non-professional phagocytic cells and replicates within endoplasmic reticulum (ER)-derived vacuoles. The host factors required for Brucella entry into host cells, avoidance of lysosomal degradation, and replication in the ER-like compartment remain largely unknown. Here we describe two assays to identify host factors involved in Brucella entry and replication in HeLa cells. The protocols describe the use of RNA interference, while alternative screening methods could be applied. The assays are based on the detection of fluorescently labeled bacteria in fluorescently labeled host cells using automated wide-field microscopy. The fluorescent images are analyzed using a standardized image analysis pipeline in CellProfiler which allows single cell-based infection scoring.
In the endpoint assay, intracellular replication is measured two days after infection. This allows bacteria to traffic to their replicative niche where proliferation is initiated around 12 hr after bacterial entry. Brucella which have successfully established an intracellular niche will thus have strongly proliferated inside host cells. Since intracellular bacteria will greatly outnumber individual extracellular or intracellular non-replicative bacteria, a strain constitutively expressing GFP can be used. The strong GFP signal is then used to identify infected cells.
In contrast, for the entry assay it is essential to differentiate between intracellular and extracellular bacteria. Here, a strain encoding for a tetracycline-inducible GFP is used. Induction of GFP with simultaneous inactivation of extracellular bacteria by gentamicin enables the differentiation between intracellular and extracellular bacteria based on the GFP signal, with only intracellular bacteria being able to express GFP. This allows the robust detection of single intracellular bacteria before intracellular proliferation is initiated.

Microscopy-based Assays for High-throughput Screening of Host Factors Involved in Brucella Infection of Hela Cells

Two assays for microscopy-based high-throughput screening of host factors involved in Brucella infection are described. The entry assay detects host factors required for Brucella entry and the endpoint assay those required for intracellular replication. While applicable for alternative approaches, siRNA screening in HeLa cells is used to illustrate the protocols.

Brucella species are facultative intracellular pathogens that infect animals as their natural hosts. Transmission to humans is most commonly caused by ...