An updated profile of the bovine acute phase response following an intravenous lipopolysaccharide challenge

Authors: SMOCK, TAYLOR - Texas Tech University; Broadway, Paul; Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; THEURER, MILES - Veterinary Research And Consulting Services Llc; HALES, KRISTIN - Texas Tech University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2023
Publication Date: 4/28/2023
Citation: Smock, T.M., Broadway, P.R., Sanchez, N.C., Carroll, J.A., Theurer, M.E., Hales, K.E. 2023. An updated profile of the bovine acute phase response following an intravenous lipopolysaccharide challenge. Journal of Animal Science. 101. Article skad133. https://doi.org/10.1093/jas/skad133.
DOI: https://doi.org/10.1093/jas/skad133

Interpretive Summary: The acute phase response is a component of innate immunity initiated by infection, inflammation, or tissue damage. Features of these host responses can be mimicked by giving bacterial endotoxin and is closely studied in controlled settings. It is also used to understand the response to inflammation in livestock. New technologies and techniques introduced over the past 15 years now allows for a more in depth understanding of this response in cattle. Beef steers were given endotoxin, and responses of body temperature, serum chemistry, complete blood count, cortisol, and cytokines were measured. A moderate correlation was found between rectal temperature and ocular infrared temperature. The response of chemistry variables highlighted the link between metabolism and immunity. The initial inflammatory response was started by cortisol and pro-inflammatory cytokines and later tempered by anti-inflammatory cytokines. These data offer an expanded view to our understanding of the bovine acute phase response. Data from this study will be of interest to veterinarians and scientists in the area of livestock health, immunology and physiology.

Technical Abstract: The objective was to provide an updated profile of the bovine acute-phase response to include recent advancements in technologies and expanded hematological, cytokine, and serum chemistry variables. Beef steers (n = 32; BW = 251 +/- 19.5 kg) were fitted with indwelling jugular catheters 1 day before lipopolysaccharide (LPS) administration to facilitate serial blood collection. Rectal temperature was measured using indwelling probes, and ocular temperature was measured using infrared thermal imaging. Blood samples were collected for subsequent analysis of serum chemistry, hematology, and cytokine concentrations. Pearson correlation of rectal temperature and ocular infrared temperature was 0.61 (P < 0.01) and the Spearman correlation coefficient was 0.56 (P < 0.01). Interactions of hour x method were observed for ocular and rectal measurements of body temperature in response to endotoxin exposure. Maximum observed temperature was 39.6 C at 2.5 h for both rectal and ocular measurements. Body temperature differed by method at hours 0.5, 2.5, 4.5, 7.5, 12.5, 36.5, and 47.5 (P < 0.01), but were not different otherwise. All variables of serum chemistry and complete blood count were influenced by LPS administration, except creatinine, serum glucose, and percent basophils (P < 0.02). Alanine aminotransferase and alkaline phosphatase peaked at hour 2 relative to LPS administration, returned to baseline at hour 12 and continued to decrease below the baseline value at hour 48 (P < 0.01). Total protein concentration decreased 3% in response to LPS (P = 0.01). Total white blood cell count decreased 75% after LPS administration at hour 1 (P < 0.01). Lymphocyte count recovered to baseline at hour 6; sooner than neutrophil count at hour 36. Serum cortisol concentration increased 294% relative to baseline at hour 1 followed by a sustained decrease and return to normal concentration at hour 4 (P < 0.01). Additionally, circulating cytokine concentrations changed with time in response to the LPS challenge, excluding aFGF, bFGF, IGF-1, IL-2, IL-4, MCP-1, and ANG-1 (P < 0.08). Maximum observed concentration of TNF-a at hour 1 was 117% greater than the pre-challenge value (P < 0.01). Data presented herein add to existing works to understand the endocrine and immune responses of beef steers administered exogenous LPS, and incorporate recent technologies, additional biomarkers, and an expanded cytokine profile that can be used as referential data in future research.