This work was supported by National Institutes of Allergy and Infectious Diseases Grant P01 A1078894 to C.A.G.

<ol>
	<li>Nathan, C., Ding, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonresolving+Inflammation.">Nonresolving Inflammation.</a> Cell. 140 (6), 871-882 (2010).</li><li>Karin, M., Lawrence, T., Nizet, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Innate+immunity+gone+awry:+linking+microbial+infections+to+chronic+inflammation+and.">Innate immunity gone awry: linking microbial infections to chronic inflammation and.</a> 124, 823-835 (2006).</li><li>Connor, S. M., Taylor, C. E., Hughes, 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=Emerging+infectious+determinants+of+chronic+diseases.">Emerging infectious determinants of chronic diseases.</a> Emerging Infectious Diseases. 12 (7), 1051-1057 (2006).</li><li>Barth, K., Remick, D. G., Genco, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+immune+regulation+by+microbial+pathogens+and+resulting+chronic+inflammation.">Disruption of immune regulation by microbial pathogens and resulting chronic inflammation.</a> Journal of Cellular Physiology. , (2012).</li><li>Hayashi, C., Gudino, C. V., Gibson, F. C., Genco, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review:+Pathogen-induced+inflammation+at+sites+distant+from+oral+infection:+bacterial+persistence+and+induction+of+cell-specific+innate+immune+inflammatory+pathways.">Review: Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways.</a> Molecular Oral Microbiology. 25 (5), 305-316 (2010).</li><li>Gibson, F. C., Ukai, T., Genco, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engagement+of+specific+innate+immune+signaling+pathways+during+Porphyromonas+gingivalis+induced+chronic+inflammation+and+atherosclerosis.">Engagement of specific innate immune signaling pathways during Porphyromonas gingivalis induced chronic inflammation and atherosclerosis.</a> Frontiers in Bioscience: a Journal and Virtual Library. 13, 2041-2059 (2008).</li><li>Pihlstrom, B. L., Michalowicz, B. S., Johnson, N. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Periodontal+diseases.">Periodontal diseases.</a> Lancet. 366 (9499), 1809-1820 (2005).</li><li>Baker, P. J., Evans, R. T., Roopenian, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oral+infection+with+Porphyromonas+gingivalis+and+induced+alveolar+bone+loss+in+immunocompetent+and+severe+combined+immunodeficient+mice.">Oral infection with Porphyromonas gingivalis and induced alveolar bone loss in immunocompetent and severe combined immunodeficient mice.</a> Archives of Oral Biology. 39 (12), 1035-1040 (1994).</li><li>Baker, P. J., Carter, S., Dixon, M., Evans, R. T., Roopenian, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+antibody+response+to+oral+infection+precedes+but+does+not+prevent+Porphyromonas+gingivalis-induced+alveolar+bone+loss+in+mice.">Serum antibody response to oral infection precedes but does not prevent Porphyromonas gingivalis-induced alveolar bone loss in mice.</a> Oral Microbiology and Immunology. 14 (3), 194-196 (1999).</li><li>Gibson, F. C., Hong, 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=Innate+immune+recognition+of+invasive+bacteria+accelerates+atherosclerosis+in+apolipoprotein+E-deficient+mice.">Innate immune recognition of invasive bacteria accelerates atherosclerosis in apolipoprotein E-deficient mice.</a> Circulation. 109 (22), 2801-2806 (2004).</li><li>Hayashi, C., Viereck, 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=Porphyromonas+gingivalis+accelerates+inflammatory+atherosclerosis+in+the+innominate+artery+of+ApoE+deficient+mice.">Porphyromonas gingivalis accelerates inflammatory atherosclerosis in the innominate artery of ApoE deficient mice.</a> Atherosclerosis. 215 (1), 52-59 (2011).</li><li>Hayashi, C., Madrigal, A. G., 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=Pathogen-mediated+inflammatory+atherosclerosis+is+mediated+in+part+via+Toll-like+receptor+2-induced+inflammatory+responses.">Pathogen-mediated inflammatory atherosclerosis is mediated in part via Toll-like receptor 2-induced inflammatory responses.</a> Journal of Innate Immunity. 2 (4), 334-343 (2010).</li><li>Hayashi, C., Papadopoulos, G., 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=Protective+role+for+TLR4+signaling+in+atherosclerosis+progression+as+revealed+by+infection+with+a+common+oral+pathogen.">Protective role for TLR4 signaling in atherosclerosis progression as revealed by infection with a common oral pathogen.</a> Journal of Immunology (Baltimore, Md.: 1950). 189 (7), 3681-3688 (2012).</li><li>Papadopoulos, G., Weinberg, E. O., 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=Macrophage-Specific+TLR2+Signaling+Mediates+Pathogen-Induced+TNF-Dependent+Inflammatory+Oral+Bone+Loss.">Macrophage-Specific TLR2 Signaling Mediates Pathogen-Induced TNF-Dependent Inflammatory Oral Bone Loss.</a> The Journal of Immunology. , (2012).</li><li>Gibson, F. C., Hong , 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=Innate+immune+recognition+of+invasive+bacteria+accelerates+atherosclerosis+in+apolipoprotein+E-deficient+mice.">Innate immune recognition of invasive bacteria accelerates atherosclerosis in apolipoprotein E-deficient mice.</a> Circulation. 109 (22), 2801-2806 (2004).</li><li>Miyamoto, T., Yumoto, H., Takahashi, Y., Davey, M., Gibson, F. C., Genco, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogen-accelerated+atherosclerosis+occurs+early+after+exposure+and+can+be+prevented+via+immunization.">Pathogen-accelerated atherosclerosis occurs early after exposure and can be prevented via immunization.</a> Infection and Immunity. 74 (2), 1376-1380 (2006).</li><li>Baker, P. J., Dixon, M., Roopenian, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+control+of+susceptibility+to+Porphyromonas+gingivalis-induced+alveolar+bone+loss+in+mice.">Genetic control of susceptibility to Porphyromonas gingivalis-induced alveolar bone loss in mice.</a> Infection and Immunity. 68 (10), 5864-5868 (2000).</li><li>Baker, P. J., Dixon, M., Evans, R. T., Roopenian, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneity+of+Porphyromonas+gingivalis+strains+in+the+induction+of+alveolar+bone+loss+in+mice.">Heterogeneity of Porphyromonas gingivalis strains in the induction of alveolar bone loss in mice.</a> Oral Microbiology and Immunology. 15 (1), 27-32 (2000).</li><li>Daugherty, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+atherosclerosis.">Mouse models of atherosclerosis.</a> The American Journal of the Medical Sciences. 323 (1), 3-10 (2002).</li><li>Weinreb, D. B., Aguinaldo, J. G. S., Feig, J. E., Fisher, E. A., Fayad, Z. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+MRI+of+mouse+models+of+atherosclerosis.">Non-invasive MRI of mouse models of atherosclerosis.</a> NMR in Biomedicine. 20 (3), 256-264 (2007).</li></ol>

The authors declare that they have no competing financial interests.

The P. gingivalis oral infection model provides a valuable tool for the study of pathogen-induced chronic inflammation at local and systemic sites. This unique model permits the characterization of both host and pathogen specific mechanisms contributing to chronic inflammation and immunopathology. In addition, the model can be used to screen for novel therapeutic strategies, including immunization and pharmacological intervention. The steps outlined in this protocol describe the successful use of this model and ...

Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans. These diseases include neoplastic, autoimmune, and chronic inflammatory diseases1. The etiology of many chronic diseases remains unclear but is understood to be complex and multifactorial, involving both genetic predisposition and the introduction of environmental factors. While the perpetuators of inflammation remain elusive, the cellular and molecular profiles of immune activation overlap considerably with those patterns observed in host responses to pathogens2. 
Mounting evidence implicates infection with microbial pathogens in the development and progression of chronic inflammation and its diverse clinical manifestations2,3. Pathogens can induce and sustain chronic inflammation directly by subverting the host immune system and establishing persistent infections4. In the absence of microbial persistence, infection can precipitate chronic inflammation from autoimmune reactions triggered by molecular mimicry to self-antigens, changes in self-antigens that render them immunogenic, or damage that releases previously masked host antigens. Rarely however have specific pathogens been identified as the universal cause of a particular chronic disease. Rather, the majority of available data suggests that pathogens use distinct mechanisms to elicit chronic inflammation with a wide spectrum of clinical manifestations and disease outcomes in the genetically susceptible host3. Thus, a detailed understanding of the mechanisms by which specific pathogens induce chronic inflammation may have major implications for public health, as well as treatment and prevention of many chronic diseases. 
Although the host and pathogen specific mechanisms contributing to the induction and maintenance of chronic inflammation are poorly understood, advances in modeling of pathogen-induced chronic inflammation have begun to further our understanding of these processes. The P. gingivalis oral infection model is a unique, well-characterized mouse model of pathogen-induced chronic inflammation that permits the analysis of host and pathogen specific mechanisms contributing to chronic inflammation at local (oral bone loss) and systemic sites (atherosclerosis)5,6. 
P. gingivalis is a Gram-negative, anaerobic oral pathogen implicated in human periodontal disease, an infection-driven chronic inflammatory disease characterized by the destruction of tooth supporting tissue7. In addition to pathology at the initial site of infection, accumulating evidence implicates P. gingivalis-induced chronic inflammation in the development and progression of systemic diseases including atherosclerosis5, a disease characterized by chronic inflammation of the arterial vessel wall. Oral infection of specific-pathogen free mice with P. gingivalis induces a local inflammatory response that results in destruction of tooth supporting alveolar bone8. P. gingivalis can be recovered from the mouths of infected mice up to 42 days post-infection8 and mice develop high levels of pathogen-specific serum antibody titers9. In an established mouse model of atherosclerosis using Apolipoprotein-E-/- mice (ApoE-/-), oral infection with P. gingivalis induces chronic inflammation that drives inflammatory plaque deposition within the aortic sinus10 and the innominate artery11. Progressive inflammation within the innominate artery of P. gingivalis-infected mice can be monitored in live animals using in vivo MRI. Histologically, arterial lesions from P. gingivalis-infected mice exhibit increased accumulation of lipids accompanied by activation of the vascular endothelium, an increased immune cell infiltrate, and elevated expression of inflammatory mediators12. Use of this model in knockout mice has elucidated the role of host signaling components and inflammatory mediators, as well as the cell specific interactions that drive P. gingivalis-induced immunopathology12&#8211;14. In addition, experiments utilizing defined bacterial mutants have identified critical P. gingivalis virulence factors contributing to chronic inflammation at local and systemic sites15. 
This article details methodologies for the assessment of P. gingivalis-induced chronic inflammation at local and systemic sites. We provide a detailed protocol for the analysis of alveolar bone loss by microCT using Amira software. In addition, we define the utility of serial in vivo live animal MRI for the assessment of progressive inflammation within the innominate artery. We include methodologies for the visualization and quantification of inflammatory plaque in arterial lesions, and describe their histological characterization. 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.

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			<td height="21" style="height:21px;width:508px;">Name of the Material/Eqiupment</td>
			<td style="width:196px;">Company</td>
			<td style="width:132px;">Catalogue Number</td>
			<td style="width:88px;">Comments&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amira analysis software</td>
			<td>Visualization Sciences Group</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anaerobic chamber DW Scientific Model MG500&#160;</td>
			<td>Microbiology International</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BHI&#160;</td>
			<td>Becton-Dickinson&#160;</td>
			<td>211059</td>
			<td></td>
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			<td height="21" style="height:21px;">Hemin&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>51280-5G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Menadione (Vitamin K)</td>
			<td>Sigma-Aldrich&#160;&#160;</td>
			<td>M5625-25G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Yeast Extract</td>
			<td>Becton-Dickinson&#160;</td>
			<td>212750</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Carboxymethyl cellulose (medium viscocity)&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>C-4888</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sulfamethoxazole and Trimethoprim Oral Suspension 200 mg/40 mg per 5ml</td>
			<td>Hi-Tech Pharmacal</td>
			<td>NDC 50383-823-16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#956;CT 40&#160;</td>
			<td>Scanco</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HistoChoice Tissue Fixative</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>H2904</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sudan IV</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>S4261-25G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">vertical-bore 11.7T Avance spectrometer&#160;</td>
			<td>Bruker</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Paravision</td>
			<td>Paravision</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ImageJ</td>
			<td>NIH</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">rat anti-mouse F4/80</td>
			<td>Serotec</td>
			<td>MCA497R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">rat anti-mouse TLR2</td>
			<td>eBioscience</td>
			<td>13-9021-80</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leica S4 Dissecting Scope</td>
			<td>Leica</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microm HM 550 Cryostat</td>
			<td>Microm</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Using the appropriate mouse model and oral infection regimen, P. gingivalis induces chronic inflammation and immunopathology at local (oral cavity) and systemic sites (arteries) (Figure 1).
In mice, oral infection with P. gingivalis induces a local inflammatory response that drives the destruction of tooth supporting alveolar bone8. P. gingivalis-infected mice develop serum antibody responses to this organism that are predominantly of the ...

Watch this Scientific Journal Video about A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites at JoVE.com

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

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 ...

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Immunology and Infection

17.4K Views.  Boston University School of Medicine. 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.