Effect of a post-weaning diet supplemented with functional feed additives on ileal transcriptome activity and serum cytokines in piglets challenged with lipopolysaccharide

This study evaluated the potential of a weanling diet supplemented with trace minerals, vitamins, prebiotics, essential oils, antioxidants and bovine colostrum (BC) to modulate the inflammatory response of low-weight (LW) and high-weight (HW) piglets challenged with lipopolysaccharide (LPS). At weaning (20 ± 1 d), litters from 32 sows were assigned to four groups: control diet (CTL), CTL plus dietary supplements (DS) or the antibiotic chlortetracycline (ATB), or DS plus BC in place of plasma proteins in the weanling diet (DS + BC). At 37 d (T0), two LW and two HW piglets were bled to evaluate ex vivo cytokine production by LPS activated peripheral blood mononuclear cells (PBMCs). In parallel, LW and HW piglets received intraperitoneal LPS and were bled at slaughter at 4 h (T4) or 18 h (T18) post-injection. Ileal tissues from these piglets and two unchallenged medium weight (MW) piglets per treatment were excised and analyzed by microarray. At T0, cytokine production of LPS-activated PBMCs was not affected by dietary treatments. At T4 after LPS challenge, serum concentrations of TNF-α, IL-6, IL-8, and IL-10 were increased in all piglets (P < 0.01). Interestingly, the LW piglets had a higher TNF-α level than the HW piglets did (P = 0.05). Dietary treatments had no effect on the piglet serum concentration of these cytokines neither at T4 nor at T18. Microarray data and QPCR analysis reveal that several genes were differentially expressed in the LPS-challenged piglets in comparison with the two control MW piglets (P < 0.001). However, the dietary treatments had a slight effect on the ileal gene expression of the T4 and T18 LPS-challenged piglets when all piglets were included in the analysis. But when body weight (LW and HW) was considered as a fixed effect, the microarray analysis showed that the expression of 54 genes was differentially modulated by the dietary treatments in the T4 and T18 LPS-challenged LW piglets (P < 0.05) while in HW piglets no difference was observed. QPCR analyses confirm that the level expression of several genes was reduced in LW piglets fed DS or DS + BC diet compared with ATB piglets. In conclusion, LPS challenge induced a transitional inflammation in weanling piglets that was characterized by increased blood-circulating cytokines and gut transcriptome activity. Results also suggest that the weanling diet supplemented with feed additives attenuated the ileal gene response to the LPS challenge, an effect that was more pronounced in the LW piglets.