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Cytokine mRNA expression in experimental porcine pneumonia
A Berndt1, M Heller, H Kosmehl
1Federal Institute for Health Protection of Consumers and Veterinary Medicine, Division 4 Bacterial Epizootics and Control of Zoonoses, Jena. a.berndt@bgvv.de
Abstract:
A porcine Pasteurella multocida (P. m.) infection model was established to study the spatial distribution of cytokine mRNA-expressing cells in lung tissue during acute pneumonia. The mRNA detection was performed by non-radioactive, formamide-free in situ hybridization (ISH) using oligonucleotides against the porcine interleukins (IL): IL-1 beta, IL-2, IL-4, IL-6, IL-8, TNF alpha and TGF beta. Cytokine mRNA-expressing macrophages were demonstrated by a double staining procedure combining immunohistochemistry (IH) using the primary antibody 2G6 with IL-1 beta, IL-6 and TGF beta ISH. With the exception of some stained TNF alpha-expressing cells, no IL mRNA was detectable in the lung of unaffected animals. The experimental P. m. pneumonia was characterized by a predominant, exudative and an additional proliferative interstitial component as well as abscess formation in the lung. Many cells of the region between the abscess membrane and the affected lung area showed high IL-6, IL-1 beta, IL-4 as well as TGF beta and few cells low IL-8 mRNA expression with characteristic distribution patterns. The ISH/IH double staining procedure revealed that at least some of the IL-6 or TGF beta-producing cells belonged to the 2G6-positive macrophages.
Insights
This study maps cytokine mRNA in pig lungs during Pasteurella multocida pneumonia. Macrophages express key cytokines like IL-6 and IL-1 beta in affected lung tissues.
Area of Science:
- Veterinary Pathology
- Immunology
- Molecular Biology
Background:
- Pneumonia is a significant disease in swine, often caused by bacterial infections like Pasteurella multocida.
- Understanding the host immune response, particularly cytokine expression, is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the spatial distribution of cytokine mRNA-expressing cells in porcine lung tissue during acute Pasteurella multocida pneumonia.
- To identify specific cytokines and cell types involved in the inflammatory response.
Main Methods:
- Establishment of a porcine Pasteurella multocida infection model.
- Non-radioactive, formamide-free in situ hybridization (ISH) for cytokine mRNA detection (IL-1 beta, IL-2, IL-4, IL-6, IL-8, TNF alpha, TGF beta).
- Double staining combining ISH with immunohistochemistry (IH) to identify cytokine-expressing macrophages.
Main Results:
- Uninfected lungs showed minimal cytokine mRNA expression, except for some TNF alpha.
- P. m. pneumonia induced exudative, proliferative, and abscess-forming lesions.
- High expression of IL-6, IL-1 beta, IL-4, and TGF beta mRNA was observed in cells surrounding abscesses.
- IL-8 mRNA was expressed at lower levels.
- Double staining confirmed that some IL-6 and TGF beta-producing cells were macrophages.
Conclusions:
- The study elucidates the spatial and cellular distribution of key cytokine mRNAs during porcine pneumonia.
- Macrophages play a significant role in the inflammatory response by producing cytokines like IL-6 and TGF beta.
- This provides insights into the pathogenesis of Pasteurella multocida-induced pneumonia in pigs.