Interpretive Summary: Breed-specific differences in the immune response to lipopolysaccharide in ewes.
By: Surely Wallace
Lipopolysaccharides (LPS) are components of gram-negative bacteria (like Escherichia coli), which stimulate the immune system to increase the cellular inflammatory response. The effects of LPS can be local to the area where the bacterial component meets the immune system, but can also have systemic effects. Differences in immune responses to bacterial infection can influence both animal health and production.
The authors of this October 2018 Journal of Animal Science article looked at how two breeds of ewes (Dorset and Suffolk) responded to an immune system challenge with bacterial LPS. They also characterized immune system genes to see if genes could explain any significant differences that might be noted in the immune responses between the two ewe breeds.
In this study, 21 Dorset ewes and 32 Suffolk ewes between 3-5 years of age (estrus synchronized) and of similar weight were included. The treatments included phosphate buffered solution (PBS) as a negative control, and LPS as the treatment. These solutions were infused intravenously. Blood samples from the ewes were subsequently collected over 24 hours.
Results indicated that ewe white blood cells decreased an hour after infusion. Ewes also had increased body temperature for four hours after infusion, but the temperature increase was more notable in the Suffolk ewes. The authors reported that the Suffolk ewes displayed more sick behaviors which were observed clinically.
Blood analysis indicated that cortisol levels (a stress response hormone) were increased in both Suffolk and Dorset ewes, but took 12 hours to return to normal levels in the Suffolk ewes, compared to 6 hours for the Dorset ewes. Pro-inflammatory and anti-inflammatory genes were also identified with PCR. The authors reported that compared to Suffolk ewes, Dorset ewes had a greater gene expression of TLR4 (aids the recognition of LPS), IL-10 (an anti-inflammatory cytokine), PPARG (gene regulator, many anti-inflammatory), FOXP3 (downregulates the immune response), and SOD2 (superoxide dismutase 2, which neutralizes toxic peroxide radicals). Compared to Dorset ewes, Suffolk ewes had a greater gene expression of IL-6 (pro-inflammatory cytokine), IFNG (proinflammatory), PTGS2 (proinflammatory) and C3 (aids in activating the complement component of the immune system).
These results indicate that there is a quantifiable difference in the immune responses to an LPS challenge between Dorset and Suffolk ewes looked at in this study. The results seem to suggest that Suffolk ewes had a more intense immune response to the LPS challenge than Dorset ewes. How this might affect these ewe breeds in response to bacterial infection, however, would need to be studied more in-depth.
To view the article, “Breed-specific differences in the immune response to lipopolysaccharide in ewes,” visit the Journal of Animal Science.