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Incubation of Pasteurella haemolytica and Pasteurella multocida lipopolysaccharide with sheep lung surfactant
Abstract:
Lipopolysaccharides (LPS) were extracted from a serotype of each of 2 species of Pasteurella isolated from sheep with respiratory tract infections. Lipopolysaccharides from P haemolytica 82-25 (serotype 1A) or P multocida P-1573 (serotype 12) were mixed with sheep lung surfactant and were incubated for 6 hours at 37 C. After incubation, LPS-surfactant mixtures were centrifuged overnight in sucrose density gradients, and fractions were analyzed. Binding occurred between LPS and surfactant vesicles resulting in a stable complex with densities greater than those with the surfactant alone. The surfactant alone had a density of 1.052 to 1.060 g/ml. Diffuse bands of surfactant had a density of 1.075 to 1.092 when incubated with P haemolytica LPS and a density of 1.069 to 1.105 when incubated with P multocida LPS.
Insights
Lipopolysaccharides (LPS) from Pasteurella species bind to sheep lung surfactant, forming stable complexes. This interaction alters the density of surfactant vesicles, offering insights into respiratory infections in sheep.
Area of Science:
- Veterinary Microbiology
- Pulmonary Immunology
- Bacterial Pathogenesis
Background:
- Pasteurella species, including Mannheimia haemolytica and Pasteurella multocida, are significant causes of respiratory tract infections in sheep.
- Lipopolysaccharides (LPS) are key components of Gram-negative bacterial outer membranes and potent immune stimulators.
- Lung surfactant plays crucial roles in respiratory mechanics and host defense within the lung alveoli.
Purpose of the Study:
- To investigate the interaction between lipopolysaccharides (LPS) from Pasteurella species and sheep lung surfactant.
- To determine if LPS binding alters the biophysical properties of sheep lung surfactant vesicles.
Main Methods:
- Lipopolysaccharides (LPS) were extracted from Pasteurella haemolytica (serotype 1A) and Pasteurella multocida (serotype 12).
- Extracted LPS were incubated with sheep lung surfactant at 37°C for 6 hours.
- LPS-surfactant mixtures were analyzed using sucrose density gradient centrifugation to assess binding and density changes.
Main Results:
- Binding was observed between LPS from both Pasteurella species and sheep lung surfactant vesicles.
- The formation of LPS-surfactant complexes resulted in increased vesicle densities compared to surfactant alone.
- Specific density shifts were recorded: surfactant incubated with P. haemolytica LPS shifted to 1.075–1.092 g/ml, and with P. multocida LPS to 1.069–1.105 g/ml.
Conclusions:
- Lipopolysaccharides from key ovine respiratory pathogens can form stable complexes with lung surfactant.
- This interaction modifies surfactant vesicle density, potentially impacting lung function and host immune response.
- Findings provide a basis for understanding the role of LPS-surfactant interactions in the pathogenesis of sheep respiratory disease.