Immunomodulatory factors and infectious agents associated with the hepatic gene expression of the IGF system in nursery pigs. (27th February 2014) - Slifierz, M. J.
Abstract : Recent findings suggest there is a complex interaction between the IGF system and the inflammatory immune response. The objective of this study was to determine whether gene expression of growth factors (IGF-1, IGF-binding protein-3 (IGFBP-3) and growth hormone receptors (GHR)) in the liver is associated with gene expression of immunomodulators in the liver, including C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (Hp), interferon- α (IFN- α ), IFN- γ, tumour necrosis factor- α (TNF- α ), interleukin (IL)-1 β, IL-6, IL-10 and IL-18, as well as with the presence of Salmonella spp., Lawsonia intracellularis, Brachyspira spp., enterotoxigenic Escherichia coli, methicillin-resistant Staphylococcus aureus, swine influenza virus, and porcine reproductive and respiratory syndrome virus (PRRSV) in nursery pigs ( n =74) from commercial farms ( n =4). Gene expression was quantified using reverse transcription quantitative-PCR (RT-qPCR) and the data were modelled using logistic regression methods. Pigs with elevated IGF-1 expression were less likely to have increased expression of TNF- α (odds ratio (OR)=0.14, P <0.01) and IL-18 (OR=0.19, P <0.05), and less likely to be colonized with PRRSV (OR=0.03, P <0.01). Pigs with increased expression of IGFBP-3 were more likely to have elevated IL-6 expression (OR=8.5, P <0.05). It was also observed that IGFBP-3 and IGF-1 were significantly associated when Hp expression was low (OR=30, P <0.05), but this association was not significant when Hp expression was high ( P =0.54). Pigs with increased expression of GHR were less likely to have elevated expression of SAA (OR=0.01, P <0.05) and IL-1β (OR=0.03, P <0.05), but more likely to have increased expression of CRP (OR=290, P <0.01). Overall, there appears to be an inverse association between the hepatic expression of the IGF system (IGF-1, IGFBP-3, GHR) and certain cytokines (IL-1 β, IL-18, TNF- α ) and acute-phase proteins (SAA, Hp).