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Updated: Jun 16, 2026
A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice
Published on: September 28, 2016
Perturbations in cytokine gene expression after inoculation of C57BL/6 mice with Pasteurella pneumotropica
Calvin C Patten1, Matthew H Myles, Craig L Franklin
1Department of Veterinary Pathobiology, University of Missouri, Columbia, USA. pattenjr@wisc.edu
Abstract:
Pasteurella pneumotropica can cause inflammation and abscess formation in a variety of tissues. Most commonly, P. pneumotropica produces clinical disease in immunodeficient mice or those concurrently infected with other pathogens. Because clinical disease is infrequent in immunocompetent mice harboring P. pneumotropica, some scientists consider it an opportunistic pathogen with little clinical relevance to biomedical research. However, other infectious agents, including mouse parvoviruses, mouse rotavirus, and Helicobacter spp. alter physiologic or biologic responses without causing clinical signs of illness. We investigated the potential for P. pneumotropica to modulate the transcription of cytokine genes in immunocompetent mice. In C57BL/6 mice inoculated oronasally with a minimal colonizing dose of P. pneumotropica, modest but statistically significant elevations of IL1beta, TNFalpha, CCL3, CXCL1, and CXCL2 mRNA were detected in mandibular and superficial cervical lymph nodes at 7 d after inoculation, and upregulation of IL1beta mRNA was detected 28 d after inoculation. These perturbations were not present in C57/BL6 mice inoculated with heat killed-P. pneumotropica or the related bacterium Actinobacillus muris. Nasal mucosal cytokine transcription did not vary significantly in C57BL/6 mice given a high dose of P. pneumotropica. These data indicate that slight and transient experimental perturbations are possible in immunocompetent mice colonized with P. pneumotropica. Knowing the full health status of experimental mice is paramount to avoid unwanted experimental variables, especially when using exquisitely sensitive testing methodologies such as those for quantification of gene expression.
Insights
Pasteurella pneumotropica can cause subtle, temporary changes in cytokine gene expression in immunocompetent mice. Monitoring mouse health is crucial for accurate gene expression studies.
Area of Science:
- Microbiology
- Immunology
- Animal Models
Background:
- Pasteurella pneumotropica is often considered an opportunistic pathogen causing disease primarily in immunocompromised hosts.
- Subclinical infections with other agents can alter host responses without overt clinical signs.
- The impact of P. pneumotropica on gene expression in immunocompetent hosts remains largely uncharacterized.
Purpose of the Study:
- To investigate the potential of P. pneumotropica to modulate cytokine gene transcription in immunocompetent mice.
- To determine if P. pneumotropica colonization can induce subclinical changes relevant to biomedical research.
Main Methods:
- Oronasal inoculation of C57BL/6 mice with a minimal colonizing dose of P. pneumotropica.
- Quantitative reverse transcription PCR (qRT-PCR) to measure mRNA levels of key cytokines (IL1beta, TNFalpha, CCL3, CXCL1, CXCL2).
- Comparison with mice inoculated with heat-killed bacteria or a related bacterium (Actinobacillus muris) and mice receiving a high dose.
Main Results:
- Modest, statistically significant elevations in IL1beta, TNFalpha, CCL3, CXCL1, and CXCL2 mRNA were detected in lymph nodes at 7 days post-inoculation.
- Upregulation of IL1beta mRNA persisted at 28 days post-inoculation.
- No significant changes were observed in mice receiving heat-killed P. pneumotropica, A. muris, or a high dose of live P. pneumotropica in nasal mucosa.
Conclusions:
- Colonization with P. pneumotropica can induce slight and transient perturbations in cytokine gene expression in immunocompetent mice.
- These subclinical changes highlight the importance of knowing the complete health status of experimental animals.
- Accurate interpretation of sensitive assays, like gene expression quantification, requires awareness of potential low-level infectious influences.
