This work was supported by the Nancy Lurie Marks Foundation. We thank Dr. Nancy E. Kohl for critical reading of the manuscript. We thank Kin K. Wong for his assistance in preparing this video report.

Note: All animal studies were performed under approved institutional protocols and animal care guidelines.
1. Reagents and Solutions
<ol>
	<li>PMA solution for s.c. inoculation: Prepare a stock solution of phorbol 12-myristate 13-acetate (PMA) at 5 mg/ml in DMSO. Store the stock solution at -20 &deg;C. Before inoculation, thaw the stock solution and dilute to 1 mg/ml PMA in PBS.</li>
	<li>LPS solution for s.c. inoculation: Dissolve lipopolysaccharide (LPS from Salmonella enterica serotype enteritidis) in sterile PBS at 1 mg/ml prior to s.c. inoculation.</li>
	<li>Luminol solution for acute phase imaging: Dissolve luminol (5-amino-2,3-dihydro-1,4-phthalazinedione, sodium salt) in sterile normal saline (0.9% NaCl) at 10 mg/ml. The solution can be stored at -20 &deg;C before use.</li>
	<li>Lucigenin solution for chronic phase imaging: Dissolve lucigenin (bis-N-methylacridinium nitrate) in sterile normal saline at 2.5 mg/ml. The solution can be stored at -20 &deg;C before use.</li>
</ol>
2. Subcutaneous PMA Inflammation Model
<ol>
	<li>Anesthetize NCr nude mice in an induction chamber with 1-2% isoflurane. Confirm general anesthesia by loss of movement and a constant respiratory rate. Transfer an animal to a nose cone supplied with isoflurane-mixed gas and keep the animal under anesthesia.</li>
	<li>Use an isopropyl alcohol wipe to clean and disinfect the injection site on the left flank.</li>
	<li>Using sterile technique, inject 50 &mu;l of the PMA inoculation solution (containing 50 &mu;g of PMA) into the subcutaneous space on the left flank. Remove excess fluid from the injection site by using an isopropyl alcohol pad. Avoid the use of analgesia as it may affect inflammatory responses.</li>
	<li>Move the animal back to the housing cage and closely monitor its recovery from anesthesia. In order to assist in the recovery, use a heating pad to keep the animal warm.</li>
</ol>
3. Subcutaneous LPS Inflammation Model
<ol>
	<li>Anesthetize C57BL/6J mice with 1-2% isoflurane in an induction chamber. Once establishing general anesthesia, transfer an animal to a nose cone supplied with isoflurane gas and keep the animal under anesthesia.</li>
	<li>Use an isopropyl alcohol wipe to clean the injection site on the left footpad.</li>
	<li>Using sterile technique, inject 50 &mu;l of the LPS inoculation solution (containing 50 &mu;g of LPS) into the left footpad. Remove excess fluid from the injection site by using an isopropyl alcohol pad. Avoid the use of analgesia as it may affect inflammatory responses.</li>
	<li>Move the animal back to the housing cage and closely monitor its recovery from anesthesia. Use a heating pad to keep the animal warm during recovery.</li>
</ol>
4. Bioluminescence Imaging of Inflammation
<ol>
	<li>Anesthetize the animal in an induction chamber with 1-2% isoflurane-mixed gas. Confirm general anesthesia by loss of movement and a constant respiratory rate.</li>
	<li>While the animal is still under anesthesia, intraperitoneally (i.p.) inject the luminol solution (10 mg/ml), or the lucigenin solution (2.5 mg/ml) for acute or chronic inflammation imaging, respectively. The final dosage is 100 mg/kg for luminol and 25 mg/kg for lucigenin. A lower dose of lucigenin (10-15 mg/kg) can be used to avoid possible toxicity for some mouse strains. Signs of toxicity include shortness of breath and respiratory distress. The C57BL/6J strain has lower lucigenin tolerability than the NCr nude strain.</li>
	<li>Transfer the animal into the imaging chamber of a bioluminescence imaging system.</li>
	<li>Perform sequential bioluminescence imaging at 1 min intervals. Each imaging step is comprised of 1 min acquisition time, f/stop = 1, binning = 16 and 0 sec delay.</li>
	<li>Within the image acquisition panel, to enable sequential multi-step imaging, click on the sequence setting button. Provide sufficient imaging steps in the acquisition profile to determine maximal luminescence output (usually 15 one-minute steps will suffice). The 15-min imaging section allows sufficient time for substrate absorption and systemic circulation.</li>
	<li>Remove the animal from the imaging chamber and move it back to the housing cage. In order to assist in the recovery, use a heating pad to keep the animal warm.</li>
	<li>During post-acquisition analysis, use the imaging software package to calculate peak total bioluminescent signal through standardized regions of interest (ROI). The images are present as radiance in photons/sec/cm2/sr with minimal and maximal threshold indicated. Quantitative data are presented as total flux in photons per second per ROI.</li>
</ol>

<ol>
	<li>Premack, B. A., Schall, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemokine+receptors:+gateways+to+inflammation+and+infection.">Chemokine receptors: gateways to inflammation and infection.</a> Nat. Med. 2, 1174-1178 (1996).</li><li>Singer, A. J., Clark, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutaneous+wound+healing.">Cutaneous wound healing.</a> N. Engl. J. Med. 341, 738-746 (1999).</li><li>Wellen, K. E., Hotamisligil, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation,+stress,+and+diabetes.">Inflammation, stress, and diabetes.</a> J. Clin. Invest. 115, 1111-1119 (2005).</li><li>Weitzman, S. A., Gordon, L. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+and+cancer:+role+of+phagocyte-generated+oxidants+in+carcinogenesis.">Inflammation and cancer: role of phagocyte-generated oxidants in carcinogenesis.</a> Blood. 76, 655-663 (1990).</li><li>Ridker, P. M., Cushman, 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=Inflammation,+aspirin,+and+the+risk+of+cardiovascular+disease+in+apparently+healthy+men.">Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men.</a> N. Engl. J. Med. 336, 973-979 (1997).</li><li>Wyss-Coray, T., Mucke, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+in+neurodegenerative+disease--a+double-edged+sword.">Inflammation in neurodegenerative disease--a double-edged sword.</a> Neuron. 35, 419-432 (2002).</li><li>Hamilton, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colony-stimulating+factors+in+inflammation+and+autoimmunity.">Colony-stimulating factors in inflammation and autoimmunity.</a> Nat. Rev. Immunol. 8, 533-544 (2008).</li><li>Harlan, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukocyte-endothelial+interactions.">Leukocyte-endothelial interactions.</a> Blood. 65, 513-525 (1985).</li><li>Bedard, K., Krause, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+NOX+family+of+ROS-generating+NADPH+oxidases:+physiology+and+pathophysiology.">The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology.</a> Physiol. Rev. 87, 245-313 (2007).</li><li>Rest, R. F., Spitznagel, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subcellular+distribution+of+superoxide+dismutases+in+human+neutrophils.+Influence+of+myeloperoxidase+on+the+measurement+of+superoxide+dismutase+activity.">Subcellular distribution of superoxide dismutases in human neutrophils. Influence of myeloperoxidase on the measurement of superoxide dismutase activity.</a> Biochem. J. 166, 145-153 (1977).</li><li>Hampton, M. B., Kettle, A. 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=Inside+the+neutrophil+phagosome:+oxidants,+myeloperoxidase,+and+bacterial+killing.">Inside the neutrophil phagosome: oxidants, myeloperoxidase, and bacterial killing.</a> Blood. 92, 3007-3017 (1998).</li><li>Serhan, C. N., Savill, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resolution+of+inflammation:+the+beginning+programs+the+end.">Resolution of inflammation: the beginning programs the end.</a> Nat. Immunol. 6, 1191-1197 (2005).</li><li>Jiang, F., Zhang, Y., 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=NADPH+oxidase-mediated+redox+signaling:+roles+in+cellular+stress+response,+stress+tolerance,+and+tissue+repair.">NADPH oxidase-mediated redox signaling: roles in cellular stress response, stress tolerance, and tissue repair.</a> Pharmacol. Rev. 63, 218-242 (2011).</li><li>Calafat, J., Kuijpers, T. W., 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=Evidence+for+small+intracellular+vesicles+in+human+blood+phagocytes+containing+cytochrome+b558+and+the+adhesion+molecule+CD11b/CD18.">Evidence for small intracellular vesicles in human blood phagocytes containing cytochrome b558 and the adhesion molecule CD11b/CD18.</a> Blood. 81, 3122-3129 (1993).</li><li>Johansson, A., Jesaitis, A. 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=Different+subcellular+localization+of+cytochrome+b+and+the+dormant+NADPH-oxidase+in+neutrophils+and+macrophages:+effect+on+the+production+of+reactive+oxygen+species+during+phagocytosis.">Different subcellular localization of cytochrome b and the dormant NADPH-oxidase in neutrophils and macrophages: effect on the production of reactive oxygen species during phagocytosis.</a> Cell. Immunol. 161, 61-71 (1995).</li><li>Kumar, A. P., Piedrafita, F. 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=Peroxisome+proliferator-activated+receptor+gamma+ligands+regulate+myeloperoxidase+expression+in+macrophages+by+an+estrogen-dependent+mechanism+involving+the+-463GA+promoter+polymorphism.">Peroxisome proliferator-activated receptor gamma ligands regulate myeloperoxidase expression in macrophages by an estrogen-dependent mechanism involving the -463GA promoter polymorphism.</a> J. Biol. Chem. 279, 8300-8315 (2004).</li><li>Tseng, J. C., Kung, 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=In+vivo+imaging+of+inflammatory+phagocytes.">In vivo imaging of inflammatory phagocytes.</a> Chem Biol. 19, 1199-1209 (2012).</li><li>Gross, S., Gammon, S. 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=Bioluminescence+imaging+of+myeloperoxidase+activity+in+vivo.">Bioluminescence imaging of myeloperoxidase activity in vivo.</a> Nat. Med. 15, 455-461 (2009).</li><li>Kielland, A., Blom, 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=In+vivo+imaging+of+reactive+oxygen+and+nitrogen+species+in+inflammation+using+the+luminescent+probe+L-012.">In vivo imaging of reactive oxygen and nitrogen species in inflammation using the luminescent probe L-012.</a> Free Radic. Biol. Med. 47, 760-766 (2009).</li><li>Zhou, J., Tsai, Y. 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=Noninvasive+assessment+of+localized+inflammatory+responses.">Noninvasive assessment of localized inflammatory responses.</a> Free Radic. Biol. Med. 52, 218-226 (2012).</li><li>Karlsson, A., Nixon, J. B., 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=Phorbol+myristate+acetate+induces+neutrophil+NADPH-oxidase+activity+by+two+separate+signal+transduction+pathways:+dependent+or+independent+of+phosphatidylinositol+3-kinase.">Phorbol myristate acetate induces neutrophil NADPH-oxidase activity by two separate signal transduction pathways: dependent or independent of phosphatidylinositol 3-kinase.</a> J. Leukoc. Biol. 67, 396-404 (2000).</li><li>Taylor, R. G., McCall, C. E., 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=Histopathologic+features+of+phorbol+myristate+acetate-induced+lung+injury.">Histopathologic features of phorbol myristate acetate-induced lung injury.</a> Lab Invest. 52, 61-70 (1985).</li><li>Fukaya, S., Matsui, Y., 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=Overexpression+of+TNF-alpha-converting+enzyme+in+fibroblasts+augments+dermal+fibrosis+after+inflammation.">Overexpression of TNF-alpha-converting enzyme in fibroblasts augments dermal fibrosis after inflammation.</a> Lab Invest. 93, 72-80 (2013).</li><li>Lu, Y. C., Yeh, W. 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=LPS/TLR4+signal+transduction+pathway.">LPS/TLR4 signal transduction pathway.</a> Cytokine. 42, 145-151 (2008).</li><li>Aitken, R. J., Buckingham, D. W., 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=Reactive+oxygen+species+and+human+spermatozoa:+analysis+of+the+cellular+mechanisms+involved+in+luminol-+and+lucigenin-dependent+chemiluminescence.">Reactive oxygen species and human spermatozoa: analysis of the cellular mechanisms involved in luminol- and lucigenin-dependent chemiluminescence.</a> J. Cell. Physiol. 151, 466-477 (1992).</li><li>Allen, R. C., Loose, L. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagocytic+activation+of+a+luminol-dependent+chemiluminescence+in+rabbit+alveolar+and+peritoneal+macrophages.">Phagocytic activation of a luminol-dependent chemiluminescence in rabbit alveolar and peritoneal macrophages.</a> Biochem. Biophys. Res. Commun. 69, 245-252 (1976).</li><li>Caldefie-Chezet, F., Walrand, 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=Is+the+neutrophil+reactive+oxygen+species+production+measured+by+luminol+and+lucigenin+chemiluminescence+intra+or+extracellular?+Comparison+with+DCFH-DA+flow+cytometry+and+cytochrome+c+reduction.">Is the neutrophil reactive oxygen species production measured by luminol and lucigenin chemiluminescence intra or extracellular? Comparison with DCFH-DA flow cytometry and cytochrome c reduction.</a> Clin. Chim. Acta. 319, 9-17 (2002).</li><li>Dahlgren, C., Aniansson, 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=Pattern+of+formylmethionyl-leucyl-phenylalanine-induced+luminol-+and+lucigenin-dependent+chemiluminescence+in+human+neutrophils.">Pattern of formylmethionyl-leucyl-phenylalanine-induced luminol- and lucigenin-dependent chemiluminescence in human neutrophils.</a> Infect. Immun. 47, 326-328 (1985).</li><li>Dahlgren, C., Karlsson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Respiratory+burst+in+human+neutrophils.">Respiratory burst in human neutrophils.</a> J. Immunol. Methods. 232, 3-14 (1999).</li><li>Aerts, C., Wallaert, B., 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=Release+of+superoxide+anion+by+alveolar+macrophages+in+pulmonary+sarcoidosis.">Release of superoxide anion by alveolar macrophages in pulmonary sarcoidosis.</a> Ann. N.Y. Acad. Sci. 465, 193-200 (1986).</li><li>Zhang, N., Francis, K. P., 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=Enhanced+detection+of+myeloperoxidase+activity+in+deep+tissues+through+luminescent+excitation+of+near-infrared+nanoparticles.">Enhanced detection of myeloperoxidase activity in deep tissues through luminescent excitation of near-infrared nanoparticles.</a> Nat Med. , (2013).</li></ol>

The authors declare no conflict of interest in this study.

In this report, we demonstrate a bioluminescence method for non-invasive imaging of inflammation in living animals. Taking advantage of two luminescent substrates, luminol and lucigenin, the method can distinguish different phases of inflammation. Luminol bioluminescence is associated with neutrophils in the acute phase of inflammation, whereas lucigenin bioluminescence is mediated by macrophages in the chronic phase. Relatively small (M.W. = 177.16 g/mol) and electrically uncharged, luminol can readily penetrate both pl...

Inflammation is a highly regulated biological response involved in a variety of human diseases, including microbial infection 1, wound healing 2, diabetes 3, cancer 4, cardiovascular 5, neurodegenerative 6, and autoimmune diseases 7. Tissue inflammation requires proper coordination of various immune cells in order to achieve pathogen clearance, tissue repair, and disease resolution. Neutrophils and macrophages are key immune mediators of tissue inflammation. In the acute phase of inflammation, neutrophils are the first responders to various harmful stimuli and tissue damage 8. The neutrophils rapidly extravasate from circulation to the site of injury, where the cells inactivate invading microbes by releasing anti-microbial granules and phagocytosis. During phagocytosis, neutrophils engulf invading microbes into phagosomes, within which the cells produce high levels of superoxide (O2&middot;-). Phagosomal superoxide is the primary source of many downstream reactive oxygen species (ROS). For example, superoxide can be dismutated to hydrogen peroxide (H2O2) by spontaneous dismutation or by superoxide dismutase (SOD) 9, 10. In neutrophils, myeloperoxidase (MPO) further converts hydrogen peroxide to anti-microbial hypochlorous acid (HOCl) 11. As the inflammatory responses continue, circulating monocytes gradually migrate into the site of injury and differentiate into mature macrophages 2, whose phagocytic function help remove inactivated pathogens and cell debris. In addition, as a key regulator in the later phase of inflammation, macrophage promotes tissue repair by producing anti-inflammatory cytokines 12 and by generating extracellular ROS at a lower level 9. The ROS generated at this later stage regulate tissue remodeling, new vessel formation, and reepithelialization 13.
Phagocyte NADPH oxidase (Phox) is the primary source of superoxide production in both neutrophils and macrophages 9. Phox is a multi-subunit complex whose assembly is tightly regulated 9. The holoenzyme contains several cytosolic regulatory subunits (p67phox, p47phox, p40phox, and RAC) and a membrane-bound heterodimer cytochrome b558 (consist of subunit CYBA and CYBB). Cytochrome b558 is the reaction core within which the CYBB subunit (also known as p91phox and NOX2) carries out the primary redox chain reaction 9. Interestingly, its assembly sites are different between neutrophils and macrophages. In resting neutrophils, cytochrome b558 is mostly present in the membrane of intracellular storage granules 14. During phagocytosis, neutrophils assemble the holoenzymes at phagosomes 9, where high levels of MPO activity are also present. The neutrophil Phox rapidly consumes oxygen and exerts its microbicidal power by ROS production, a phenomenon termed the respiratory burst 11. In contrast, macrophages have a lower level of MPO expression and cytochrome b558 is mostly found in the plasma membrane 15, 16. Thus neutrophils produce high levels of superoxide for anti-microbial activity, while macrophages generate less superoxide for regulatory functions 15.
Since inflammation is an intricate in vivo process, non-invasive imaging methods specific for different phases of inflammation would allow quantitative and longitudinal assessment of disease models. Using mechanistic studies, we have previously demonstrated the use of two chemiluminescent agents, luminol (5-amino-2,3-dihydro-1,4-phthalazinedione) and lucigenin (bis-N-methylacridinium nitrate), for non-invasive imaging of acute and late (chronic) stages of inflammation, respectively 17. Luminol enables visualization of neutrophil MPO activity in the acute phase of inflammation 18-20, whereas lucigenin bioluminescence can be used to assess macrophage activity in association with the late phase or chronic inflammation 17. In this manuscript, we used two experimental inflammation models (s.c. PMA and s.c. LPS) to demonstrate these imaging techniques.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Phorbol 12-myristate 13-acetate (PMA)</td>
			<td>Sigma-Aldrich Co., St. Louis, MO</td>
			<td>P8139</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lipopolysaccharide from Salmonella enterica serotype enteritidis</td>
			<td>Sigma-Aldrich Co., St. Louis, MO</td>
			<td>L2012</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Luminol (5-amino-2,3-dihydro-1,4-phthalazinedione, sodium salt)</td>
			<td>Sigma-Aldrich Co., St. Louis, MO</td>
			<td>A4685</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lucigenin (bis-N-methylacridinium nitrate)</td>
			<td>Sigma-Aldrich Co., St. Louis, MO</td>
			<td>M8010</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>IVIS Spectrum imaging system with Living Imaging 4.2 software package</td>
			<td>Caliper LS/Perkin Elmer, Hopkinton, MA</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

in vivo imaging method to distinguish acute and chronic inflammation

Inflammation is a fundamental aspect of many human diseases. In this video report, we demonstrate non-invasive bioluminescence imaging techniques that distinguish acute and chronic inflammation in mouse models. With tissue damage or pathogen invasion, neutrophils are the first line of defense, playing a major role in mediating the acute inflammatory response. As the inflammatory reaction progresses, circulating monocytes gradually migrate into the site of injury and differentiate into mature macrophages, which mediate chronic inflammation and promote tissue repair by removing tissue debris and producing anti-inflammatory cytokines. Intraperitoneal injection of luminol (5-amino-2,3-dihydro-1,4-phthalazinedione, sodium salt) enables detection of acute inflammation largely mediated by tissue-infiltrating neutrophils. Luminol specifically reacts with the superoxide generated within the phagosomes of neutrophils since bioluminescence results from a myeloperoxidase (MPO) mediated reaction. Lucigenin (bis-N-methylacridinium nitrate) also reacts with superoxide in order to generate bioluminescence. However, lucigenin bioluminescence is independent of MPO and it solely relies on phagocyte NADPH oxidase (Phox) in macrophages during chronic inflammation. Together, luminol and lucigenin allow non-invasive visualization and longitudinal assessment of different phagocyte populations across both acute and chronic inflammatory phases. Given the important role of inflammation in a variety of human diseases, we believe this non-invasive imaging method can help investigate the differential roles of neutrophils and macrophages in a variety of pathological conditions.

We performed longitudinal bioluminescence imaging to assess acute and chronic inflammation in experimental inflammation models. Phorbol 12-myristate 13-acetate (PMA) is a potent protein kinase C (PKC) agonist that activates Phox for superoxide anion production and triggers intense acute inflammatory responses 21. S.C. injection of 50 mg of PMA in NCr nude mice caused rapid skin irritation and acute inflammation at injection sites 18, 22, 23. We performed daily imaging for 4 days with the first image...

Watch this Scientific Journal Video about In vivo Imaging Method to Distinguish Acute and Chronic Inflammation at JoVE.com

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

We describe a non-invasive imaging method for distinguishing inflammatory stages. Systemic delivery of luminol reveals areas of acute inflammation dependent upon MPO activity in neutrophils. In contrast, injection of lucigenin allows for visualization of chronic inflammation dependent upon Phox activity in macrophages.

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

Inflammation is a fundamental aspect of many human diseases. In this video report, we demonstrate non-invasive bioluminescence imaging techniques that ...

in-vivo-imaging-method-to-distinguish-acute-and-chronic-inflammation

Research

JoVE Journal

Immunology and Infection

20.1K Views.  Harvard Medical School. We describe a non-invasive imaging method for distinguishing inflammatory stages. Systemic delivery of luminol reveals areas of acute inflammation dependent upon MPO activity in neutrophils. In contrast, injection of lucigenin allows for visualization of chronic inflammation dependent upon Phox activity in macrophages.

Video: In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists. The value of 2P microscopy is that it provides rich spatiotemporal information regarding cell behaviors within intact tissues and in live mice. Leukocyte recruitment plays a significant role in host defense against infection and when unchecked, can contribute to inflammatory and autoimmune diseases. Studying leukocyte recruitment in vivo is technically challenging since cells are moving rapidly within vessels located deep within light scattering tissues. To date, most intravital imaging studies require surgical preparation to expose the blood vessels and tissues. To avoid the tissue damage and inflammation induced by surgery itself, here, we describe a non-invasive single-cell imaging approach that can be used to study leukocyte trafficking in the mouse footpad and phalanges. We discuss the technical aspects of our 2P imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Here, we describe a non-invasive two-photon (2P) microscopy approach to study leukocyte homing in the mouse footpad. We discuss the technical aspects of our tissue imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists.  The value of 2P microscopy is that it ...

Using Eggs from Schistosoma mansoni as an In vivo Model of Helminth-induced Lung Inflammation

Schistosoma parasites are blood flukes that infect an estimated 200 million people worldwide 1. In chronic infection with Schistosoma, the severe pathology, including liver fibrosis and splenomegaly, is caused by the immune response to the parasite eggs rather than the parasite itself 2. Parasite eggs induce a Th2 response characterized by the production of IL-4, IL-5 and IL-13, the alternative activation of macrophages and the recruitment of eosinophils. Here, we describe injection of Schistosoma mansoni eggs as a model to examine parasite-specific Th2 cytokine responses in the lung and draining lymph nodes, the formation of pulmonary granulomas surrounding the egg, and airway inflammation. 
Following intraperitoneal sensitization and intravenous challenge, S. mansoni eggs are transported to the lung via the pulmonary arteries where they are trapped within the lung parenchyma by granulomas composed of lymphocytes, eosinophils and alternatively activated macrophages 3-6. Associated with granuloma formation, inflammation in the broncho-alveolar spaces, expansion of the draining lymph nodes and CD4 T cell activation can be observed. Here we detail the protocol for isolating Schistosoma mansoni eggs from infected livers (modified from 7), sensitizing and challenging mice, and recovering the organs (broncho-alveolar lavage (BAL), lung and draining lymph nodes) for analysis. We also include representative histologic and immunologic data and suggestions for additional immunologic analysis. 
Overall, this method provides an in vivo model to investigate helminth-induced immunologic responses in the lung, which is broadly applicable to the study of Th2 inflammatory diseases including helminth infection, fibrotic diseases, allergic inflammation and asthma. Advantages of this model for the study of type 2 inflammation in the lung include the reproducibility of a potent Th2 inflammatory response in the lung and draining lymph nodes, the ease of assessment of inflammation by histologic examination of the granulomas surrounding the egg, and the potential for long-term storage of the parasite eggs.

Using Eggs from Schistosoma mansoni as an In vivo Model of Helminth-induced Lung Inflammation

Schistosoma mansoni eggs are potent stimulators of the T helper type 2 (Th2) immune response, characteristic of parasite infection, asthma and allergic inflammation. This protocol utilizes S. mansoni egg injection to generate a CD4 Th2 cytokine-induced inflammatory response in the lung, characterized by lung granuloma formation around the egg, eosinophilia and macrophage alternative activation.

Schistosoma parasites are blood flukes that infect an estimated 200 million people worldwide 1. In chronic infection with Schistosoma, the severe ...

Bioluminescent Bacterial Imaging In Vivo

This video describes the use of whole body bioluminesce imaging (BLI) for the study of bacterial trafficking in live mice, with an emphasis on the use of bacteria in gene and cell therapy for cancer. Bacteria present an attractive class of vector for cancer therapy, possessing a natural ability to grow preferentially within tumors following systemic administration. Bacteria engineered to express the lux gene cassette permit BLI detection of the bacteria and concurrently tumor sites. The location and levels of bacteria within tumors over time can be readily examined, visualized in two or three dimensions. The method is applicable to a wide range of bacterial species and tumor xenograft types. This article describes the protocol for analysis of bioluminescent bacteria within subcutaneous tumor bearing mice. Visualization of commensal bacteria in the Gastrointestinal tract (GIT) by BLI is also described. This powerful, and cheap, real-time imaging strategy represents an ideal method for the study of bacteria in vivo in the context of cancer research, in particular gene therapy, and infectious disease. This video outlines the procedure for studying lux-tagged E. coli in live mice, demonstrating the spatial and temporal readout achievable utilizing BLI with the IVIS system.

Bioluminescent Bacterial Imaging In Vivo

This article describes the administration of lux-tagged bacteria to mice and subsequent in vivo analysis using IVIS bioluminescence imaging.

This video describes the use of whole body bioluminesce imaging (BLI) for the study of bacterial trafficking in live mice, with an emphasis on the use of ...

A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites

Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans including neoplastic, autoimmune, and chronic inflammatory diseases. Emerging evidence implicates pathogen-induced chronic inflammation in the development and progression of chronic diseases with a wide variety of clinical manifestations. Due to the complex and multifactorial etiology of chronic disease, designing experiments for proof of causality and the establishment of mechanistic links is nearly impossible in humans. An advantage of using animal models is that both genetic and environmental factors that may influence the course of a particular disease can be controlled. Thus, designing relevant animal models of infection represents a key step in identifying host and pathogen specific mechanisms that contribute to chronic inflammation.
Here we describe a mouse model of pathogen-induced chronic inflammation at local and systemic sites following infection with the oral pathogen Porphyromonas gingivalis, a bacterium closely associated with human periodontal disease. Oral infection of specific-pathogen free mice induces a local inflammatory response resulting in destruction of tooth supporting alveolar bone, a hallmark of periodontal disease. In an established mouse model of atherosclerosis, infection with P. gingivalis accelerates inflammatory plaque deposition within the aortic sinus and innominate artery, accompanied by activation of the vascular endothelium, an increased immune cell infiltrate, and elevated expression of inflammatory mediators within lesions. We detail methodologies for the assessment of inflammation at local and systemic sites. The use of transgenic mice and defined bacterial mutants makes this model particularly suitable for identifying both host and microbial factors involved in the initiation, progression, and outcome of disease. Additionally, the model can be used to screen for novel therapeutic strategies, including vaccination and pharmacological intervention.

Animal models have proven to be invaluable tools in defining host and pathogen specific mechanisms that contribute to the development of chronic inflammation. Here we describe a mouse model of oral infection with the human pathogen Porphyromonas gingivalis and detail methodologies to assess the progression of inflammation at local and systemic sites.

Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans including ...

An Optimized Method for Isolating and Expanding Invariant Natural Killer T Cells from Mouse Spleen

The ability to rapidly secrete cytokines upon stimulation is a functional characteristic of the invariant natural killer T (iNKT) cell lineage. iNKT cells are therefore characterized as an innate T cell population capable of activating and steering adaptive immune responses. The development of improved techniques for the culture and expansion of murine iNKT cells facilitates the study of iNKT cell biology in in vitro and in vivo model systems. Here we describe an optimized procedure for the isolation and expansion of murine splenic iNKT cells.
Spleens from C57Bl/6 mice are removed, dissected and strained and the resulting cellular suspension is layered over density gradient media. Following centrifugation, splenic mononuclear cells (MNCs) are collected and CD5-positive (CD5+) lymphocytes are enriched for using magnetic beads. iNKT cells within the CD5+ fraction are subsequently stained with &#945;GalCer-loaded CD1d tetramer and purified by fluorescence activated cell sorting (FACS). FACS sorted iNKT cells are then initially cultured in vitro using a combination of recombinant murine cytokines and plate-bound T cell receptor (TCR) stimuli before being expanded in the presence of murine recombinant IL-7. Using this technique, approximately 108 iNKT cells can be generated within 18-20 days of culture, after which they can be used for functional assays in vitro, or for in vivo transfer experiments in mice.

Here we present an adapted protocol that can be used to generate a large number of murine invariant natural killer T cells from mouse spleen. The protocol outlines an approach by which splenic iNKT cells can be enriched for, isolated and expanded in vitro using a limited number of animals and reagents.

The ability to rapidly secrete cytokines upon stimulation is a functional characteristic of the invariant natural killer T (iNKT) cell lineage. iNKT cells ...

A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice

Although community-acquired pneumonia remains a major public health problem, murine models of bacterial pneumonia have recently facilitated significant preclinical advances in our understanding of the underlying cellular and molecular pathogenesis. In vivo mouse models capture the integrated physiology and resilience of the host defense response in a manner not revealed by alternative, simplified ex vivo approaches. Several methods have been described in the literature for intrapulmonary inoculation of bacteria in mice, including aerosolization, intranasal delivery, peroral endotracheal cannulation under &#39;blind&#39; and visualized conditions, and transcutaneous endotracheal cannulation. All methods have relative merits and limitations. Herein, we describe in detail a non-invasive, technically non-intensive, inexpensive, and rapid method for intratracheal delivery of bacteria that involves aspiration (i.e., inhalation) by the mouse of an infectious inoculum pipetted into the oropharynx while under general anesthesia. This method can be used for pulmonary delivery of a wide variety of non-caustic biological and chemical agents, and is relatively easy to learn, even for laboratories with minimal prior experience with pulmonary procedures. In addition to describing the aspiration pneumonia method, we also provide step-by-step procedures for assaying the subsequent in vivo pulmonary innate immune response of the mouse, in particular, methods for quantifying bacterial clearance and the cellular immune response of the infected airway. This integrated and simple approach to pneumonia assessment allows for rapid and robust evaluation of the effect of genetic and environmental manipulations upon pulmonary innate immunity.

Several methods have been described in the literature for modeling bacterial pneumonia in mice. Herein, we describe a non-invasive, inexpensive, rapid method for inducing pneumonia via aspiration (i.e., inhalation) of a bacterial inoculum pipetted into the oropharynx. Downstream methods for assessment of the pulmonary innate immune response are also detailed.

Although community-acquired pneumonia remains a major public health problem, murine models of bacterial pneumonia have recently facilitated significant ...

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models.
Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent

This paper explains the application of fluorescent imaging using an activatable optical imaging probe to visualize the in vivo activity of key matrix metalloproteinases in two different experimental models of inflammation.

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo ...

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo Cell Trafficking by PET/CT

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte cell culture and 64Cu-antibody receptor targeting of the cells. In vitro evaluation of the radiolabel and non-invasive in vivo cell tracking in an animal model of an airway delayed-type hypersensitivity reaction (DTHR) by PET/CT are described.
In detail, the conjugation of a mAb with the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is shown. Following the production of radioactive 64Cu, radiolabeling of the DOTA-conjugated mAb is described. Next, the expansion of chicken ovalbumin (cOVA)-specific CD4+ interferon (IFN)-&#947;-producing T helper cells (cOVA-TH1) and the subsequent radiolabeling of the cOVA-TH1 cells are depicted. Various in vitro techniques are presented to evaluate the effects of 64Cu-radiolabeling on the cells, such as the determination of cell viability by trypan blue exclusion, the staining for apoptosis with Annexin V for flow cytometry, and the assessment of functionality by IFN-&#947; enzyme-linked immunosorbent assay (ELISA). Furthermore, the determination of the radioactive uptake into the cells and the labeling stability are described in detail. This protocol further describes how to perform cell tracking studies in an animal model for an airway DTHR and, therefore, the induction of cOVA-induced acute airway DHTR in BALB/c mice is included. Finally, a robust PET/CT workflow including image acquisition, reconstruction, and analysis is presented.
The 64Cu-antibody receptor targeting approach with subsequent receptor internalization provides high specificity and stability, reduced cellular toxicity, and low efflux rates compared to common PET-tracers for cell labeling, e.g.64Cu-pyruvaldehyde bis(N4-methylthiosemicarbazone) (64Cu-PTSM). Finally, our approach enables non-invasive in vivo cell tracking by PET/CT with an optimal signal-to-background ratio for 48 h. This experimental approach can be transferred to different animal models and cell types with membrane-bound receptors that are internalized.

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo  Cell Trafficking by PET/CT

Following the preparation of a 64Cu-modified monoclonal antibody binding to a transgenic murine T cell receptor, T cells are radiolabeled in vivo, analyzed for viability, functionality, labeling stability and apoptosis, and adoptively transferred into mice with an airway delayed-type hypersensitivity reaction for non-invasive imaging by positron emission tomography/computed tomography (PET/CT).

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte ...

An Efficient and Simple Method to Establish NK and T Cell Lines from Patients with Chronic Active Epstein-Barr Virus Infection

A number of methods have been described to establish NK/T cell lines from patients with lymphoma or lymphoproliferative syndrome. These methods employed feeder cells, purified NK or T cells with as much as 10 mL of blood, or a high-dose of IL-2. This study presents a new method with a powerful and simple strategy to establish NK and T cell lines by culturing the peripheral blood mononuclear cells (PBMC) with the addition of recombinant human IL-2 (rhIL-2), and uses as little as 2 mL of whole blood. The cells can proliferate quickly in two weeks and be maintained for more than 3 months. With this method, 7 NK or T cell lines have been established with a high success rate. This method is simple, reliable, and applicable to establishing cell lines from more cases of CAEBV or NK/T cell lymphoma.

A simple method for obtaining NK and T cell clones from CAEBV patients was developed with high efficiency, a small amount of peripheral blood, and a low-dose of IL-2.

A number of methods have been described to establish NK/T cell lines from patients with lymphoma or lymphoproliferative syndrome. These methods employed ...

Long-term In Vivo Tracking of Inflammatory Cell Dynamics Within Drosophila Pupae

During the rapid inflammatory response to tissue damage, cells of the innate immune system are quickly recruited to the injury site. Once at the wound, innate immune cells perform a number of essential functions, such as fighting infection, clearing necrotic debris, and stimulating matrix deposition. In order to fully understand the diverse signaling events that regulate this immune response, it is crucial to observe the complex behaviors of (and interactions that occur between) multiple cell lineages in vivo, and in real-time, with the high spatio-temporal resolution. The optical translucency and the genetic tractability of Drosophila embryos have established Drosophila as an invaluable model to live-image and dissect fundamental aspects of inflammatory cell behavior, including mechanisms of developmental dispersal, clearance of apoptotic corpses&#160;and/or microbial pathogens, and recruitment to wounds. However, more recent work has now demonstrated that employing a much later stage in the Drosophila lifecycle &#8211; the Drosophila pupa &#8211; offers a number of distinct advantages, including improved RNAi efficiency, longer imaging periods, and significantly greater immune cell numbers. Here we describe a protocol for imaging wound repair and the associated inflammatory response at the high spatio-temporal resolution in live Drosophila pupae. To follow the dynamics of both re-epithelialization and inflammation, we use a number of specific in vivo fluorescent markers for both the epithelium and innate immune cells. We also demonstrate the effectiveness of photo-convertible fluorophores, such as Kaede, for following the specific immune cell subsets, to track their behavior as they migrate to, and resolve from, the injury site.

Long-term In Vivo Tracking of Inflammatory Cell Dynamics Within Drosophila Pupae

Here we present a protocol for live-imaging wound repair and the associated inflammatory response at high spatio-temporal resolution in vivo. This method utilizes the pupal stage of Drosophila development to enable long-term imaging and tracking of specific cell populations over time and is compatible with efficient RNAi-mediated gene inactivation.

During the rapid inflammatory response to tissue damage, cells of the innate immune system are quickly recruited to the injury site. Once at the wound, ...