Response of Ipec-J2 Cells and Jejunal Explants to Treatment with Rhamnolipids

Rhamnolipids (RL) are glycolipids secreted by bacteria that aid in motility, biofilm formation, nutrient uptake, and have antimicrobial activity. The latter two may be of use to improve swine nutrition and health. Work conducted in vitro utilized IPEC-J2 cells to determine cellular response to treatment. In the first experiment, cells were treated with 0, 0.01, 0.05, 0.5, 1.0, 2.4, and 10% RL or 1 ug/mL lipopolysaccharide (LPS). In the second experiment, cells were treated with 0, 0.0005, 0.001, 0.005, and 0.01% RL or 1 ug/mL LPS. For both experiments, treated cells were incubated for 1 h and rinsed with PBS. Cells were further incubated in fresh non-treated media for 0, 1, 3, 6, 12 or 24 h in Exp. 1, or 6 h in Exp. 2. Transepithelial resistance (TER) measurements were collected immediately after addition of fresh media and final incubation. Media was collected from both sides of Trans-well inserts for IL-8 analysis. Visual observation and TER analysis of Exp. 1 showed RL treatment decreased TER after initial incubation, with RL concentrations ≥ 0.05% exhibiting significant cell death and loss of cellular matrix adherence to the Trans-well membrane. Using lower dosages in Exp. 2, TER changed inversely with RL dosage, however, even 0.0005% RL reduced TER by at least 20% over the 6 h period (P > 0.10). Production of IL-8 was lower in RL treatments compared with either the control or LPS wells on the apical side (P > 0.10). Basolateral IL-8 was expressed in a dose dependent fashion, but only the 0.01% RL had higher expression than the control (P > 0.10). A third experiment was conducted by culturing jejunal explants in media with 0, 0.0005, 0.005, 0.05, and 0.5% RL or 1 ug/mL LPS for 1 h followed by 3 h incubation in fresh media. Similarly to Exp. 2, explants showed dose dependent IL-8 production in 5 and 7 wk old tissue with 0.5% RL having higher IL-8 concentration compared to control or LPS samples (P < 0.01). The lower doses of RL had similar or lower IL-8 production to the control or LPS samples (P > 0.10). Together these data show that low doses of RL (≤ 0.005%) can significantly impact IPEC-J2 TER, but do not cause increases in IL-8 production. More data is needed to determine the effect of RL on nutrient absorption, gut health, and the microbiome in pigs.