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Updated: Jul 21, 2026
The Bovine Lung in Biomedical Research: Visually Guided Bronchoscopy, Intrabronchial Inoculation and In Vivo Sampling Techniques
Published on: July 3, 2014
Tilmicosin does not inhibit interleukin-8 gene expression in the bovine lung experimentally infected with Mannheimia
Abstract:
The expression of the interleukin-8 (IL-8) gene was examined by in situ hybridization in lung tissues from calves experimentally infected with Mannheimia (Pasteurella) haemolytica and treated with tilmicosin. Interleukin-8 mRNA expression was detected in alveolar areas, particularly along interlobular septa, in the lumen, and in the epithelial cells of some bronchioles. In lesional lung tissues from animals that had received tilmicosin, we found large areas with limited inflammation. There was no staining for IL-8 mRNA in these areas. In contrast, in strongly inflamed areas, the same patterns and intensities of staining for IL-8 mRNA were detected in tilmicosin- and sham-treated animals. We conclude that tilmicosin does not affect the expression of IL-8 mRNA in tissue showing microscopic signs of inflammation. Together with previous reports, this supports the view that the pro-apoptotic properties of tilmicosin on neutrophils do not compromise the host defense mechanisms required to control the infection.
Insights
Tilmicosin treatment did not alter interleukin-8 (IL-8) gene expression in inflamed lung tissues of calves infected with Mannheimia haemolytica. This suggests tilmicosin preserves crucial host defense mechanisms against bacterial pneumonia.
Area of Science:
- Veterinary Pathology
- Bovine Respiratory Disease
- Pharmacology
Background:
- Mannheimia haemolytica causes significant economic losses in the cattle industry due to bovine respiratory disease.
- Interleukin-8 (IL-8) is a key chemokine involved in neutrophil recruitment during bacterial infections.
- Tilmicosin is a macrolide antibiotic used to treat respiratory infections in cattle, but its effect on host immune response requires further clarification.
Purpose of the Study:
- To investigate the impact of tilmicosin on interleukin-8 (IL-8) gene expression in the lung tissues of calves experimentally infected with Mannheimia haemolytica.
- To determine if tilmicosin affects neutrophil-mediated inflammatory responses in the context of bovine respiratory disease.
Main Methods:
- In situ hybridization was employed to detect IL-8 mRNA expression in lung tissues.
- Calves were experimentally infected with Mannheimia haemolytica and treated with either tilmicosin or a sham treatment.
- Lung tissues were analyzed for IL-8 mRNA localization and intensity in both lesional and non-lesional areas.
Main Results:
- IL-8 mRNA expression was observed in alveolar areas, interlobular septa, bronchiolar lumen, and epithelial cells.
- In lung tissues with limited inflammation following tilmicosin treatment, no IL-8 mRNA staining was detected.
- Strongly inflamed areas in both tilmicosin- and sham-treated animals exhibited similar patterns and intensities of IL-8 mRNA expression.
Conclusions:
- Tilmicosin does not suppress IL-8 gene expression in lung tissues exhibiting microscopic signs of inflammation.
- The findings support the hypothesis that tilmicosin's pro-apoptotic effects on neutrophils do not impair essential host defense mechanisms required for controlling Mannheimia haemolytica infections.
- Tilmicosin appears to be a safe therapeutic option that does not compromise the innate immune response in the treatment of bovine respiratory disease.
