Effect of longevity genotype on acute phase response to a lipopolysaccharide challenge in dairy goats

The present study aims to explore the phenotypic variability of the inflammatory response to a lipopolysaccharide (LPS) challenge in goats and compare the reaction between two lines divergently selected for functional longevity. Hyper-selection based on functional longevity successfully created two groups of goats with different lifespans (High_LGV and Low_LGV). Primiparous goats were injected intravenously with LPS to trigger an inflammatory response, with a total of 83 goats, including 42 High_LGV and 41 Low_LGV goats. Blood was sampled 12 times at -72, 0 (injection), 2, 4, 6, 8, 10, 12, 24, 48, 72, and 144 hours. Baseline cytokine concentrations (average of hours -72 and 0) showed no significant differences between longevity lines for any of the 14 measured cytokines. Among the six cytokines that responded to the LPS challenge (IFN-γ, IL4, IL-6, IL-10, MIP1α, and TNFα), three showed significant differences between longevity lines in their temporal response profiles. Low_LGV goats exhibited stronger acute inflammatory responses with greater IL-6 and IFN-γ concentrations during the early hours post-challenge, while High_LGV goats showed elevated MIP1α concentrations during the resolution phase. In parallel, whole blood was stimulated for 24 hours with LPS on a total of 157 goats for ex vivo assessment of the blood response. The IL-6 concentration measured in the whole blood assay showed a moderate correlation with the in vivo response and revealed no difference between the longevity lines. These results suggest that a stronger acute inflammatory response, characterised by elevated pro-inflammatory cytokine production, may be detrimental to functional longevity in dairy goats, possibly through increased tissue damage and impaired recovery following inflammatory challenges.