Modulation of the innate immune response to lipopolysaccharide through ghrelin administration in weaned pigs

Authors: Sanchez, Nicole; Dailey, Jeffery; Broadway, Paul; DAVIS, EMILY - Texas Tech University; BOWEN, BROOKE - Texas Tech University; PETRY, AMY - Texas Tech University; BALLOU, MICHAEL - Texas Tech University; HALES, KRISTEN - Texas Tech University; Carroll, Jeffery - Jeff Carroll

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/2022
Publication Date: 5/1/2023
Citation: Sanchez, N.C., Dailey, J.W., Broadway, P.R., Davis, E.M., Bowen, B.M., Petry, A.L., Ballou, M.A., Hales, K.E., Carroll, J.A. 2023. Modulation of the innate immune response to lipopolysaccharide through ghrelin administration in weaned pigs. Journal of Animal Science Supplement. 101(1):70-71.

Interpretive Summary:

Technical Abstract: Ghrelin is a hormone produced in the gastrointestinal tract that is known to stimulate feed intake. However, recent evidence suggests a role for ghrelin in reducing inflammation. Therefore, this study was designed to determine whether repeated ghrelin administration prior to and following an inflammatory challenge would alter the innate immune response. Weaned pigs (n = 36) were acquired and transported to the Livestock Issues Research Unit’s Swine Building where they were housed in individual pens in an environmentally controlled room. Pigs had ad libitum access to water and a starter ration. Two days following arrival, pigs were fitted with two separate temperature loggers within the intraperitoneal cavity (IP) or subcutaneously between the abdomen and the hind leg (Flank). After 3 days, pigs were fitted with jugular vein catheters under anesthesia to allow for serial blood collection. Based on body weight measured following cannulation, pigs were separated into 2 treatments 1) Ghrelin: administered human ghrelin (5 µg/kg BW iv) every 12 h from -48 to 36 h relative to LPS administration at 0 h; 2) Control: administered saline at previously mentioned time points. Blood samples were collected at -48, -36, -24, -12, -2, -1, 0, 1, 2, 3, 4, 5, 6, 12, 24, 36 and 48 h relative to LPS administration. After collection of the 48-h sample, pigs were humanely euthanized, and samples of the jejunum and ileum were collected for histology. Ghrelin pigs gained more weight (P = 0.04) compared to Control pigs throughout the study. There was a treatment × time interaction (P = 0.03) for Flank temperature where Ghrelin pigs had greater body temperature at 0, 2, 4 and 48 h post-LPS challenge. Neutrophil and basophil concentrations and the neutrophil:lymphocyte ratio were reduced (P = 0.04) in Ghrelin pigs compared to Control pigs. Additionally, there was a treatment × time interaction for eosinophil concentration (P = 0.03), where concentrations were reduced in Ghrelin pigs compared to Control pigs at 0 and 36 h post-LPS challenge. There were treatment × time interactions for serum concentrations of Tumor necrosis factor-alpha, Interferon-gamma, Granulocyte-Macrophage-Colony Stimulating Factor, and Interleukin-4 (P = 0.04), with greater concentrations observed in Ghrelin compared to Control pigs. However, there was no effect of ghrelin administration of cortisol concentrations (P = 0.38). In the ileum, Ghrelin pigs had greater villi length, yet reduced villus blunting score, lacteal dilation score, and lamina propria eosinophil count compared to Control pigs (P = 0.04). Data from this study suggests ghrelin may provide protection against endotoxin-induced inflammation in the ileum, while increasing basal concentrations of cytokines. Further research is necessary to fully understand the impact of ghrelin on the inflammatory response in weaned pigs.