Relations among enterotoxigenic Escherichia coli, net fluid absorption, and cytokine expression in piglet jejunal segments infused with customized glycans

Abstract Text: Adherence of enterotoxigenic Escherichia coli (ETEC) to small intestine mucosa produces toxins that cause diarrhea and intestinal inflammation. Lactobacillus reuteri produce glycans that may reduce ETEC-associated disturbances in swine; however, benefits of such glycans to prevent pathogen adhesion in vivo have not been proven. We hypothesized that customized functional glycans obtained from lactic acid bacteria production reduce intestinal incidence of ETEC-derived fluid loss and expression of inflammatory cytokines (interleukin (IL)-1β and IL-6) in piglets. Weanling gilts (5-wk-old; 10.2 ± 1.8 kg BW; n = 11) were surgically prepared with 10 jejunal segments using small intestinal perfusion in 2 Exp. In each pig, 5 segments were infected with ETEC K88 (5 × 10⁹ CFU/mL); remaining segments were flushed with saline (PBS). Five pairs of segments, 1 ETEC and 1 non-ETEC infected, were infused with customized glycans or saline as control for 8 hr. Glycans infused in Exp. 1 were dextran, inulin, levan, and reuteran; in Exp. 2, galactooligosaccharide (GOS), chitosan-oligosaccharide (COS), galactosylated COS (Gal-COS), and a negative control containing glucose and galactose were used. After infusion, segments were removed, net fluid absorption (NFA) and loss (NFL) per surface area and expression of IL-1β and IL-6 were determined and differences analyzed using ANOVA. Principal component (PC) analyses showed infection with ETEC had a strong negative relation with NFA and a strong positive relation with cytokine expression. Compared to saline, NFL was decreased in COS, dextran, levan, and reuteran (57, 59, 40, and 49, respectively, vs. 105 ± 20 mL cm^-2; P < 0.05). Although ETEC increased (P < 0.05) IL-1β in all segments, difference of fold change in IL-1β between ETEC and PBS was decreased in GOS compared to saline (0.1 vs 2.5; P < 0.05). There was no difference in fold change in IL-6 expression due to ETEC infection between treatments. In conclusion, customized glycans may reduce net fluid loss and some markers of intestinal inflammation related to ETEC adherence in the small intestine.

Keywords: enterotoxigenic Escherichia coli, diarrhea, inflammation