This work was supported by NIH grants HL-089779 (DW), HL-112270 (KAP) and HL-102836 (KAP) and Cimphoni Life Sciences (part of DW salary). The authors thank Meghann Sytsma for editing the manuscript.

This study was carried out in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. The protocol was approved by the Institutional Animal Care and Use Committee (Protocol: AUA#1517). All research involving mice was conducted in conformity with PHS policy.
1. Design of Decoy Peptide
<ol>
	<li>Find the IRF5&#39;s 3D structure and base the design on it. Design a 17 mer, termed IRF5D (ELDWDADDIRLQIDNPD), where aspartate (D) is substit...

<ol>
	<li>Bi, X., 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=Loss+of+interferon+regulatory+factor+5+(IRF5)+expression+in+human+ductal+carcinoma+correlates+with+disease+stage+and+contributes+to+metastasis.">Loss of interferon regulatory factor 5 (IRF5) expression in human ductal carcinoma correlates with disease stage and contributes to metastasis.</a> Breast Cancer Res. 13 (6), 111 (2011).</li><li>Dideberg, V., 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=An+insertion-deletion+polymorphism+in+the+interferon+regulatory+Factor+5+(IRF5)+gene+confers+risk+of+inflammatory+bowel+diseases.">An insertion-deletion polymorphism in the interferon regulatory Factor 5 (IRF5) gene confers risk of inflammatory bowel diseases.</a> Hum Mol Genet. 16 (24), 3008-3016 (2007).</li><li>Graham, R. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+common+haplotype+of+interferon+regulatory+factor+5+(IRF5)+regulates+splicing+and+expression+and+is+associated+with+increased+risk+of+systemic+lupus+erythematosus.">A common haplotype of interferon regulatory factor 5 (IRF5) regulates splicing and expression and is associated with increased risk of systemic lupus erythematosus.</a> Nat.Genet. 38 (5), 550-555 (2006).</li><li>Krausgruber, 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=IRF5+promotes+inflammatory+macrophage+polarization+and+TH1-TH17+responses.">IRF5 promotes inflammatory macrophage polarization and TH1-TH17 responses.</a> Nat. Immunol. 12 (3), 231-238 (2011).</li><li>Eames, H. L., Corbin, A. L., Udalova, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interferon+regulatory+factor+5+in+human+autoimmunity+and+murine+models+of+autoimmune+disease.">Interferon regulatory factor 5 in human autoimmunity and murine models of autoimmune disease.</a> Transl Res. 167 (1), 167-182 (2016).</li><li>Mayes, M. D., 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=Immunochip+analysis+identifies+multiple+susceptibility+Loci+for+systemic+sclerosis.">Immunochip analysis identifies multiple susceptibility Loci for systemic sclerosis.</a> Am J Hum Genet. 94 (1), 47-61 (2014).</li><li>Dimitroulas, 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=Micro-and+Macrovascular+Treatment+Targets+in+Scleroderma+Heart+Disease.">Micro-and Macrovascular Treatment Targets in Scleroderma Heart Disease.</a> Curr Pharm Des. , (2013).</li><li>Botstein, G. R., LeRoy, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+heart+disease+in+systemic+sclerosis+(scleroderma):+advances+in+clinical+and+pathologic+features,+pathogenesis,+and+new+therapeutic+approaches.">Primary heart disease in systemic sclerosis (scleroderma): advances in clinical and pathologic features, pathogenesis, and new therapeutic approaches.</a> Am Heart J. 102 (5), 913-919 (1981).</li><li>Oram, S., Stokes, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+heart+in+scleroderma.">The heart in scleroderma.</a> Br Heart J. 23 (3), 243-259 (1961).</li><li>Xu, H., 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=4F+decreases+IRF5+expression+and+activation+in+hearts+of+tight-skin+mice.">4F decreases IRF5 expression and activation in hearts of tight-skin mice.</a> PLoS One. 7 (12), 52046 (2012).</li><li>Steen, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+heart+in+systemic+sclerosis.">The heart in systemic sclerosis.</a> Curr.Rheumatol.Rep. 6 (2), 137-140 (2004).</li><li>Deshpande, N., 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+RCSB+Protein+Data+Bank:+a+redesigned+query+system+and+relational+database+based+on+the+mmCIF+schema.">The RCSB Protein Data Bank: a redesigned query system and relational database based on the mmCIF schema.</a> Nucleic Acids Res. 33, D233-D237 (2005).</li><li>Concepcion, J., 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=Label-free+detection+of+biomolecular+interactions+using+biolayer+interferometry+for+kinetic+characterization.">Label-free detection of biomolecular interactions using biolayer interferometry for kinetic characterization.</a> Comb Chem High Throughput Screen. 12 (8), 791-800 (2009).</li><li>Matthew, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+biosensor+technologies+in+drug+discovery.">Current biosensor technologies in drug discovery.</a> Drug Discovery. , 69 (2006).</li><li>Doppelt-Azeroual, O., Moriaud, F., Adcock, S. A., Delfaud, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+MED-SuMo+applications.">A review of MED-SuMo applications.</a> Infect Disord Drug Targets. 9 (3), 344-357 (2009).</li><li>Kim, S., Jang, J., Yu, J., Chang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+mucosal+immunization+of+recombinant+adenovirus-based+vaccine+expressing+F1+protein+fragment+induces+protective+mucosal+immunity+against+respiratory+syncytial+virus+infection.">Single mucosal immunization of recombinant adenovirus-based vaccine expressing F1 protein fragment induces protective mucosal immunity against respiratory syncytial virus infection.</a> Vaccine. 28 (22), 3801-3808 (2010).</li><li>Frenzel, D., Willbold, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+Titration+Series+with+Biolayer+Interferometry.">Kinetic Titration Series with Biolayer Interferometry.</a> PloS one. 9 (9), 106882 (2014).</li><li>Ou, J., 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=L-4F,+an+apolipoprotein+A-1+mimetic,+dramatically+improves+vasodilation+in+hypercholesterolemia+and+sickle+cell+disease.">L-4F, an apolipoprotein A-1 mimetic, dramatically improves vasodilation in hypercholesterolemia and sickle cell disease.</a> Circulation. 107 (18), 2337-2341 (2003).</li><li>Bradford, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+and+sensitive+method+for+the+quantitation+of+microgram+quantities+of+protein+utilizing+the+principle+of+protein-dye+binding.">A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.</a> Anal.Biochem. 72 (1-2), 248-254 (1976).</li><li>Bauer, P. 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=Compensatory+phosphorylation+and+protein-protein+interactions+revealed+by+loss+of+function+and+gain+of+function+mutants+of+multiple+serine+phosphorylation+sites+in+endothelial+nitric-oxide+synthase.">Compensatory phosphorylation and protein-protein interactions revealed by loss of function and gain of function mutants of multiple serine phosphorylation sites in endothelial nitric-oxide synthase.</a> J.Biol.Chem. 278 (17), 14841-14849 (2003).</li><li>Weihrauch, D., 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=An+IRF5+Decoy+Peptide+Reduces+Myocardial+Inflammation+and+Fibrosis+and+Improves+Endothelial+Cell+Function+in+Tight-Skin+Mice.">An IRF5 Decoy Peptide Reduces Myocardial Inflammation and Fibrosis and Improves Endothelial Cell Function in Tight-Skin Mice.</a> PLoS One. 11 (4), 0151999 (2016).</li><li>Hoogenboom, H. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibody+phage+display+technology+and+its+applications.">Antibody phage display technology and its applications.</a> Immunotechnology. 4 (1), 1-20 (1998).</li><li>Roehm, N. W., Rodgers, G. H., Hatfield, S. M., Glasebrook, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+colorimetric+assay+for+cell+proliferation+and+viability+utilizing+the+tetrazolium+salt+XTT.">An improved colorimetric assay for cell proliferation and viability utilizing the tetrazolium salt XTT.</a> J Immunol Methods. 142 (2), 257-265 (1991).</li><li>Van Tonder, A., Joubert, A. M., Cromarty, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Limitations+of+the+3-(4,+5-dimethylthiazol-2-yl)-2,+5-diphenyl-2H-tetrazolium+bromide+(MTT)+assay+when+compared+to+three+commonly+used+cell+enumeration+assays.">Limitations of the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay when compared to three commonly used cell enumeration assays.</a> BMC Res Notes. 8 (1), 1 (2015).</li><li>Ott, H. 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=Perfusion-decellularized+matrix:+using+nature's+platform+to+engineer+a+bioartificial+heart.">Perfusion-decellularized matrix: using nature's platform to engineer a bioartificial heart.</a> Nat Med. 14 (2), 213-221 (2008).</li><li>Ou, J., 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=L-4F,+an+apolipoprotein+A-1+mimetic,+dramatically+improves+vasodilation+in+hypercholesterolemia+and+sickle+cell+disease.">L-4F, an apolipoprotein A-1 mimetic, dramatically improves vasodilation in hypercholesterolemia and sickle cell disease.</a> Circulation. 107 (18), 2337-2341 (2003).</li><li>Weihrauch, D., 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=Effects+of+D-4F+on+vasodilation,+oxidative+stress,+angiostatin,+myocardial+inflammation,+and+angiogenic+potential+in+tight-skin+mice.">Effects of D-4F on vasodilation, oxidative stress, angiostatin, myocardial inflammation, and angiogenic potential in tight-skin mice.</a> Am J Physiol Heart Circ Physiol. 293 (3), 1432-1441 (2007).</li><li>Roy, S., P, P., Mavragani, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IRF-5+-+A+New+Link+to+Autoimmune+Diseases.">IRF-5 - A New Link to Autoimmune Diseases.</a> Autoimmune Disorders - Pathogenetic Aspects. , 35 (2011).</li></ol>

The authors declare that they have no competing financial interests.

The goal was to design an IRF5 inhibitor to elucidate the role of IRF5 on inflammation, fibrosis, and vascular function in the hearts of Tsk/+ mice. The findings are that IRF5D did not induce proliferation or apoptosis. Moreover, inflammation was reduced and vascular function improved. These data suggest that IRF5 plays an important mechanistic role in the development of inflammation and fibrosis in the heart of Tsk/+ mice and that it has the potential to serve as a therapeutic target.
The fir...

Regulation of cell growth and cell death immune responses is central to the role of the transcription factor family of interferon regulatory factors. IRF5 is highlighted as being crucial for the regulation of immune responses between type 1, an inflammatory promoting response and type 2, an immune response targeting tissue repair. IRF5 is key in cancer1, and autoimmunity2,3,4,5.
The tight-skin mouse (Tsk/+) is a model for tissue fibrosis and scleroderma due to a duplication mutation in the fibrillin-1 gene. This mutation results in a tight-skin and an increase in connective tissue. These mice develop myocardial inflammation, fibrosis and finally heart failure5,6,7,8,9. Scleroderma is an autoimmune fibrotic disorder affecting approximately 150,000 patients in the United States6. The hallmarks of this disease are fibrosis of internal organs including the heart7,8,9,10,11.
The nature of the study demanded the design of an inhibitory peptide. The software approach was chosen over a traditional approach using a phage display. The software approach is easier and less time consuming. The RCSB data bank is used to identify appropriate binding sites12. To study the interaction of the newly designed peptide with the recombinant protein and to focus on the binding parameters, a technique called biolayer interferometry was used. Biolayer interferometry is a biosensor based technique that determines binding affinity, association and disassociation using a biosensor and a binding sample. The biosensor can be fluorescently, luminescently, radiometrically and colorimetrically labeled. The measurement is based on mass addition or depletion resembling association and disassociation13,14. The aim of this study was to understand the role of IRF5 in myocardial inflammation and fibrosis. The goal was to gain insight into the role of IRF5 in the development of tissue fibrosis and scleroderma.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>&#160;Triton X 100</td>
			<td>Sigma Aldrich</td>
			<td>X100- 100ml</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa 488-labeled goat anti-mouse IgG antibody&#160;</td>
			<td>Thermo Fisher</td>
			<td>A11001</td>
			<td></td>
		</tr>
		<tr>
			<td>Bardford reagent</td>
			<td>Thermo Fisher</td>
			<td>23200</td>
			<td>Pierce&#160;</td>
		</tr>
		<tr>
			<td>Biosensors</td>
			<td>Forte-Bio</td>
			<td>MR18-0009</td>
			<td></td>
		</tr>
		<tr>
			<td>CD64 (H-250)</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-15364</td>
			<td></td>
		</tr>
		<tr>
			<td>CellEvent Caspase-3/7 Substrate</td>
			<td>Thermo Fisher/Life Technologies</td>
			<td>C10427</td>
			<td></td>
		</tr>
		<tr>
			<td>CellTiter AQueous One Solution Cell Proliferation Assay kit</td>
			<td>Promega</td>
			<td>G3580</td>
			<td>Promega</td>
		</tr>
		<tr>
			<td>DAPI (4&#8242;,6-diamidino-2-phenylindole)</td>
			<td>Thermo Fisher</td>
			<td>D-1306</td>
			<td>1:1000 dilution in PBS</td>
		</tr>
		<tr>
			<td>donkey anti rat Alexa 488</td>
			<td>Thermo Fisher</td>
			<td>A-21208</td>
			<td>1:1000 dilution in PBS</td>
		</tr>
		<tr>
			<td>ECL plus</td>
			<td>GE healthcare/Amersham</td>
			<td>RPN2133</td>
			<td>After a lot of trial and error we came back to this one</td>
		</tr>
		<tr>
			<td>Eclipse TE 200-U microscope with EZ C1 laser scanning software</td>
			<td>Nikon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>goat anti rabbit Alexa 488</td>
			<td>Thermo Fisher</td>
			<td>A-11008</td>
			<td>1:1000 dilution in PBS</td>
		</tr>
		<tr>
			<td>HRP&#160; anti-goat</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-516086</td>
			<td>!:10000 dilution in TBS</td>
		</tr>
		<tr>
			<td>HRP donkey anti-mouse</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-2315</td>
			<td>1:10000 dilution in TBS</td>
		</tr>
		<tr>
			<td>ICAM-1 antibody</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-1511</td>
			<td>1:200 dilution in PBS</td>
		</tr>
		<tr>
			<td>IRF5 antibody (H56)</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-98651</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro plate reader Elx800</td>
			<td>Biotek</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NIMP neutrophil marker</td>
			<td>Santa Cruz Biotechnologies</td>
			<td>sc-133821</td>
			<td>1:200 dilution in PBS</td>
		</tr>
		<tr>
			<td>Octet RED</td>
			<td>Forte Bio</td>
			<td></td>
			<td>protein-protein binding</td>
		</tr>
		<tr>
			<td>Peptide design&#160; Medit SA software</td>
			<td>RCSB.org</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant IRF5 protein synthesis</td>
			<td>TopGene Technologies</td>
			<td></td>
			<td>protein expression, synthesis service</td>
		</tr>
		<tr>
			<td>sodium dodecyl phosphate</td>
			<td>Sigma Aldrich</td>
			<td>436143</td>
			<td>detergent</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Pharmacy</td>
			<td></td>
			<td>Schedule III controlled substance, presciption required&#160;</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>MedVet</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3.5X-45X Trinocular Dissecting Zoom Stereo Microscope with Gooseneck LED Lights</td>
			<td>Am Scope</td>
			<td>SKU: SM-1TSX-L6W</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeba Desalting Columns</td>
			<td>Thermofisher</td>
			<td>2161515</td>
			<td></td>
		</tr>
		<tr>
			<td>Endothelial Basal Media EBM Bullet kit</td>
			<td>Lonza</td>
			<td>CC-3124</td>
			<td>kit contains growth supplemets</td>
		</tr>
		<tr>
			<td>VIA-100K</td>
			<td>&#160;Boeckeler Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4-15% TGX gel</td>
			<td>Bio-Rad</td>
			<td>5671081</td>
			<td></td>
		</tr>
		<tr>
			<td>MedSuMo software</td>
			<td>Medit, Palaiseau, France</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Laemmli Buffer</td>
			<td>BioRad</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

vasodilation of isolated vessels and the isolation of the extracellular matrix of tight-skin mice

The interferon regulatory factor 5 (IRF5) is crucial for cells to determine if they respond in a pro-inflammatory or anti-inflammatory fashion. IRF5's ability to switch cells from one pathway to another is highly attractive as a therapeutic target. We designed a decoy peptide IRF5D with a molecular modeling software for designing small molecules and peptides.
IRF5D inhibited IRF5, reduced alterations in extracellular matrix, and improved endothelial vasodilation in the tight-skin mouse (Tsk/+). The Kd of IRF5D for recombinant IRF5 is 3.72 &plusmn; 0.74 x 10-6 M as determined by binding experiments using biolayer interferometry experiments. Endothelial cells (EC) proliferation and apoptosis were unchanged using increasing concentrations of IRF5D (0 to 100 &#181;g/mL, 24 h). Tsk/+ mice were treated with IRF5D (1 mg/kg/d subcutaneously, 21 d). IRF5 and ICAM expressions were decreased after IRF5D treatment. Endothelial function was improved as assessed by vasodilation of facialis arteries from Tsk/+ mice treated with IRF5D compared to Tsk/+ mice without IRF5D treatment. As a transcription factor, IRF5 traffics from the cytosol to the nucleus. Translocation was assessed by immunohistochemistry on cardiac myocytes cultured on the different cardiac extracellular matrices. IRF5D treatment of the Tsk/+ mouse resulted in a reduced number of IRF5 positive nuclei in comparison to the animals without IRF5D treatment (50 &#181;g/mL, 24 h). These findings demonstrate the important role that IRF5 plays in inflammation and fibrosis in Tsk/+ mice.

The results demonstrated in Figure 1 show how to design a peptide. Figure 1, upper left, shows the region (between the 2 yellow arrows, amino acids (aa) 425-436) in IRF5 that is phosphorylated by a number of kinases. Figure 1, upper right, shows a yellow oval where IRF5&#39;s phosphorylated domain binds. The dimeric structure of 3DSH was rotated to observe a cleft or valley to the left of the Helix 2 (aa303-312). This is where the phospho...

Watch this Scientific Journal Video about Vasodilation of Isolated Vessels and the Isolation of the Extracellular Matrix of Tight-skin Mice at JoVE.com

Vasodilation of Isolated Vessels and the Isolation of the Extracellular Matrix of Tight-skin Mice

We describe the isolation of cardiac extracellular matrix from C57Bl/6J control mice, tight-skin mice, and tight-skin mice treated with the IRF5 inhibitory peptide. We also describe the vasodilation studies on the isolated vessels from C57Bl/6J, tight-skin mice and tight-skin mice treated with the IRF5 inhibitory peptide.

The interferon regulatory factor 5 (IRF5) is crucial for cells to determine if they respond in a pro-inflammatory or anti-inflammatory fashion. IRF5's ...

The overall goal of these procedures for isolation of extracellular matrix and ex vivo vasodilation is to study IRF5 inhibitory peptide treatment in rodents. This method can help answer how changes in the extracellular matrix can augment or attenuate disease progression. The main advantage of the vasodilation studies is to give us an insight into in vivo processes without having to take all the signaling components into consideration.The isolation of cardiac extracellular matrix can be applied to other organs such as hind-limb or lung. We first had the idea when we started to focus on the duplication of fibrillin one in the tight skin mouse, and recognized the impact of altered extracellular matrix and cell behavior. After anesthetizing the mouse and preparing it for surgery, open the skin using a pair of scissors.Cutting up from the chest to lateral to the jawbone with care as to not disturb the underlying tissue towards the front of the jaw. Then dissect the fascialis artery by removing the soft tissue around it. While doing this, be careful to avoid damaging the artery.Bathe the exposed tissue in mops buffer so they remain healthy. Once the fascialis artery has been fully exposed, grasp the fascialis proximal to the first bifurcation distal to where the artery will be cut. Then, cut it away from the parent artery and take hold of the fascialis artery with the forceps.Cut the two branches coming off the fascialis and then gently lift the vessel while severing connections to surrounding tissue until the bifurcation is reached. At the bifurcation, cut both daughter arteries to free the vessel and transfer it into a dish of mops buffer where it will remain hydrated until needed. To measure vasodilation, first prepare to cannulate the vessels.Load glass pipettes with a terminal diameter of 125 to 175 microns full of mops buffer. Also fill solution reservoirs with mops. Now cannulate the isolated vessels.Tie them onto glass pipettes using opthalmic suture. Be sure to prevent air bubbles from forming in the pipettes. Next, mount the vessel chambers on an inverted microscope with the video camera attachment.Run the video through the video caliper measurement system for an on screen measurement of the vessels. Now pressurize the vessels using a two step process. First raise the mops filled reservoirs at a height above the vessel for 20 millimeters of mercury of pressure.Open the line with the mops to the vessel. As the vessel pressurizes look for signs of leaking around the ties and down the length of the vessel. If no leaks are found, raise the reservoirs to produce 60 millimeters of mercury of pressure.Then inspect the vessels for leaks again. Once the pressure is maintained without leaks, equilibrate the vessel for 30 minutes at this pressure. After being equilibrated, measure vasodilation in response to a compound of interest.First constrict the vessel by one half to three quarters by adding U46619. Let the solution bathe the vessels for six minutes to stabilize. Then, gradually add the test compound to the bath solution such as acetylcholine.Every two minutes, increase the concentration of the test solution in the bath by 10 beginning at 000001 molar and progressing to 001 molar. The changes in vasodilation raised questions about signaling. But our focus is on the heart.To reduce the use of animals, we chose to isolate cardiac extracellular matrix to focus on the signaling initiated from the outside. Begin by collecting the heart from an anesthetized mouse. Transfer it to a beaker loaded with 15 milliliters of hypertonic one percent sodium dodecyl sulfate.Keep the solution stirring gently on a stir plate at room temperature for 18 hours. The next day, change the solution to 15 milliliters of 5 percent triton X100 for 30 minutes followed by 15 milliliters of PBS for 15 minutes. Then snap freeze the ECM and liquid nitrogen in a 1.5 milliliter microcentrifuge tube.Once frozen, transfer the tissue into a pre-cooled mortar and pestle and grind it into a powder. Suspend the powder in PBS with added antibiotic at a 1:100 concentration in a viscous solution. Sonicate the suspension for 30 to 60 seconds in an ice bath at a high sonication setting.ECM protein is now isolated and must stay cold. Before using the protein, measure its concentration using a Bradford Assay. The IRF5D peptide is an inhibitory peptide that differs greatly from normal IRF5.IRF5D has only 17 amino acids and binds to IRF5's phosphorylation site. This prevents phosphorylation and homodimerization, thus interfering with the formation of the IRF5 active state. Heterozygous tight skin mice were treated with IRF5D subcutaneously for three weeks.The number of neutrophil and CD64 were decreased as determined by immunohistochemistry in the average number of stained cells per field of view. IRF5D treatments improved acetylcholine induced vasodilation of fascialis arteries in heterozygous tight skin mice treated with IRF5D compared to those treated with phosphate buffer. In cultured myocytes derived from the cardiac tissue of the transgenic mice, there were more IRF5 positive cells in cultures from tight skin heterozygous mice than in control mice.Treatment of either culture with IRF5D resulted in a reduction of IRF5 positive nuclei. After watching this video, you should have a good understanding of how to decellularize a heart. Once mastered, this technique can be transposed to many organs and aid to answer a variety of questions And remember that it is important not to overdigest the matrix.You should also have a good understanding of how to dissect and hang the fascialis artery. Once mastered, this technique should take approximately 60 minutes and can be used on just about any vascular bed. It is important to remember how fragile the endothelium is, proceed with caution during the dissection.It is not uncommon to have healthy smooth muscle and damaged endothelium.

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Research

JoVE Journal

Immunology and Infection

8.0K Views.  Medical College of Wisconsin. The overall goal of these procedures for isolation of extracellular matrix and ex vivo vasodilation is to study IRF5 inhibitory peptide treatment in rodents. This method can help answer how changes in the extracellular matrix can augment or attenuate disease progression. The main advantage of the vasodilation studies is to give us an insight into in vivo processes without having to take all the signaling components into consideration.The isolation of cardiac extracellular matrix can be...