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The aim of the present study was to investigate systematically the expression of inflammasome components in pig intestine and to analyze the influence of age and long-term supplementation with the probiotic Enterococcus faecium NCIMB 10415 (E. faecium). In order to examine probiotic effects on the inflammasomes during a challenge with pathogens, enterotoxigenic Escherichia coli (ETEC) and E. faecium were directly added to pig jejunum in Ussing chambers.
The mRNA expression of inflammasome components generally decreased in an oral-aboral direction in intestinal tissues. In 29-day-old piglets, the expression levels of NLRP3 were significantly higher and ASC (apoptotic speck-like protein containing a caspase recruitment domain) expression were lower compared with those in the ileum of 70-day-old pigs (p ≤ 0.05). Long-term supplementation with E. faecium significantly increased ASC expression levels in the jejunum and ileum of 29-day-old piglets compared to control animals (p ≤ 0.05). Ex vivo addition of ETEC or E. faecium did not affect mRNA expression of inflammasome components significantly, whereas IL-1β protein release was significantly elevated in ETEC-incubated jejunum (p ≤ 0.05), providing evidence for the functional activation of the inflammasome, which was prevented by pre-incubation with E. faecium.
We conclude that pre-incubation with E. faecium has a protective effect during ETEC challenge; this effect is probably not located at the inflammasome transcription level. The results of this study of the expression and regulation of inflammasome components in pigs are similar to those obtained in humans, reinforcing the use of pigs as a suitable model for translational inflammasome research.