Abstract
Due to increasing concerns about the use of antibiotic growth promoters (AGP) in livestock production and their complete ban in the European Union in 2006, suitable alternatives are urgently needed. Among others, anti-inflammatory activities of AGP are discussed as their putative mode of action. As numerous phytochemicals are known to modulate the cellular antioxidant capacity and immune response, we studied the antioxidative and anti-inflammatory properties of a phytogenic (plant-derived) feed additive (PFA) in intestinal porcine epithelial cells (IPEC-J2). The effects of the PFA were compared with those of selected phytogenic ingredients (grape seed extract [GRS], licorice extract [LIC], menthol [MENT], methyl salicylate [MES], oak bark extract [OAK], oregano essential oil [ORE], and a plant powder mix [PLA]), and with the effects of the AGP tylosin (TYL). Oxidative or inflammatory stress was induced by stimulating IPEC-J2 with hydrogen peroxide (H2O2; 0.5 mM) or tumor necrosis factor alpha (TNF-α; 10 ng/mL), respectively. The antioxidative effects of feed additives were assessed with a reactive oxygen species (ROS)-sensitive probe and by measuring the expression of 6 antioxidative target genes via quantitative real-time PCR (RT-qPCR). Anti-inflammatory potential was analyzed using a nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) reporter gene assay. Moreover, the expression levels of 6 NF-κB target genes were measured using RT-qPCR analysis, and the release of IL-6 was analyzed via ELISA. Significant decreases in cellular ROS upon H2O2 treatment were observed for the PFA (P < 0.001), LIC (P < 0.001), ORE (P < 0.05), and GRS (P < 0.01). No significant changes in the expression of antioxidative genes were found. NF-κB activation upon TNF-α treatment was significantly inhibited by the PFA (P < 0.05) and by ORE (P < 0.001). Moreover, the PFA and ORE significantly reduced the gene expression of IL-6 (P < 0.001), IL-8 (P < 0.001), and C-C motif chemokine ligand 2 (CCL2; P < 0.05), as well as the release of IL-6 (P < 0.05). The other phytogenic compounds as well as the AGP TYL did not significantly affect any of the inflammatory parameters. In summary, we revealed the antioxidative properties of the PFA, LIC, ORE, and GRS, as well as anti-inflammatory properties of the PFA and ORE in IPEC-J2, providing a better understanding of the mode of action of this PFA under our experimental conditions.
Highlights
Gastrointestinal health in pigs is directly related to animal productivity and is a major concern for the modern swine industry
Untreated control cells had significantly lower levels of cellular reactive oxygen species (ROS) compared with cells stimulated with 0.5 mM H2O2, which were defined as 100% (P < 0.001; Figure 2)
All tested concentrations of Digestarom DC (D-DC) (150, 300, and 600 μg/mL) significantly decreased ROS production compared with H2O2-stimulated cells (P < 0.001), as did the 2 higher concentrations of LIC (30 and 60 μg/mL; P < 0.001) (Figure 2A and B)
Summary
Gastrointestinal health in pigs is directly related to animal productivity and is a major concern for the modern swine industry. Since the ban of AGP in the European Union in 2006, phytogenic (plant-derived) feed additives (PFA) have attracted considerable attention in livestock industry (Windisch et al, 2008). Numerous studies have reported beneficial effects of PFA on growth performance and feed conversion, in swine and poultry (Hashemi and Davoodi, 2011). To optimize the use of PFA in animal production and implement them as viable alternatives to AGP, the field will need a more detailed understanding of their mechanism of action, of potential effects on immune regulation and redox homeostasis
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