Macleaya cordata extract reduces inflammatory responses of intestinal epithelial cells in vitro

The EU ban on antimicrobial growth promoters (AGP) has initiated a search for nonantibiotic alternatives. It has been demonstrated that certain antibiotics and non-antibiotic alternatives enhance growth by inhibiting inflammatory cells, i.e. neutrophils and macrophages in the intestine. There is very little information on the effect of anti-inflammatory compounds on intestinal epithelial cells, which are known to play an important role in intestinal inflammatory responses. In order to establish this, a porcine intestinal epithelial cell line (IPEC J2) was incubated with an adherent enterotoxigenic E. coli (ETEC) to stimulate inflammation, using a non-pathogenic non-adherent E. coli (EC) as a control. The influence of the presence of the anti-inflammatory compounds Macleaya cordata extract (MCE) and acetylsalicylic acid (ASA) on inflammatory transcriptional responses was studied. ETEC induced a strong inflammatory response as was most evident from the expression of IL-1β, IL-8 and TNF-α, whereas EC induced IL-1β only. Co-incubation with MCE and ASA significantly reduced the responses of the pro-inflammatory cytokines, similarly for IL-1β and TNF-α, but ASA was more effective than MCE in reducing the IL8 response. The present results suggest that the in vivo anti-inflammatory growth promoting effects of AGP and effective alternatives to AGP such as MCE and ASA are not restricted to inflammatory cells and also involve the more abundant enterocytes. This suggests a major role for epithelial cells in growth promotion livestock, and it further supports the notion that effective alternatives to AGP should have anti-inflammatory activity.