PSXII-19 - Pediococcus Acidilactici and Lactobacillus Helveticus Inhibit Enterotoxigenic Escherichia coli Adhesion to Porcine IPEC-J2 Intestinal Cells but Do Not Protect Paracellular Epithelial Permeability

Abstract: Weaning is a critical period during swine production, as pigs endure multiple stressors. Stressors provide an opportunistic gut environment for development of enterotoxigenic Escherichia coli (ETEC) diarrheal disease. Probiotics are known to improve gut health, but the specific mechanisms to protect intestinal barrier function are unknown. The objective is to investigate protective effects of Pediococcus acidilactici (PA) and Lactobacillus helveticus (LH) against ETEC challenge using porcine IPEC-J2 intestinal epithelial cells. IPEC-J2 cells were seeded at a concentration of 1 ×10⁵ cells/insert, grown for 4 d, then treated with PA or LH for 3 h at concentrations of 10⁸, 10⁹, 10¹⁰, and 10¹¹colony forming units (CFU)/mL. Bacterial adherence assays were performed to determine probiotic CFU adhered to the cells. To assess probiotic inhibition of ETEC adherence, cells were treated with probiotics at previously defined concentrations and ETEC 3030-2: K88ac (multiplicity of infection 2:1) for 2 h. Following incubation ETEC adherence assays were conducted. Cell cytotoxicity was assessed by lactate dehydrogenase (LDH), and paracellular permeability was measured using 4-kDa fluorescein isothiocyanate-dextran (FITC-dextran). Data were analyzed according to a randomized block design using GLM procedures of SAS. Both probiotics exhibited a concentration-dependent ability to attach to epithelial cells (PA 5.05, 6.03, 6.96, 7.67 ± 0.08 log₁₀CFU/cm² P < 0.001; LH 5.54, 6.24, 7.38, 8.16 ± 0.19 log₁₀CFU/cm² P < 0.001). In the presence of ETEC, probiotic treatment linearly inhibited ETEC adherence (PA 23.49, 31.48, 4.59, 0.17 ± 6.85 % of control P < 0.001; LH 39.50, 28.0, 0.49, 0.020 ± 5.21 % of control P < 0.001). Increasing concentrations of probiotics modulated IPEC-J2 cellular cytotoxicity in the presence of ETEC (P < 0.05). However, the probiotics were not able to protect FITC-dextran flux across the epithelial cell barrier following ETEC challenge. Our findings indicate these probiotics have protective effects in preventing ETEC adhesion and modulating cell death, but do not reduce paracellular flux.