RNA form baker's yeast cultured with and without lipopolysaccharide (LPS) modulates gene transcription in an intestinal epithelial cell model, RTgutGC from rainbow trout (Oncorhynchus mykiss).

The objective of this study was to evaluate if the intestinal RTgutGC cell line could be suitable for research on dietary ingredients and their function as modulators of inflammation during lipopolysaccharide (LPS) induced stress. The RTgutGC cells cultured together with RNA from baker's yeast, reached confluency after 72 h. The cells were grown in either compete L-15 (CM) or nutrient deprived L-15 (DM). Then, the RTgutGC cells were exposed to LPS or RNA from baker's yeast, either alone, or in combination, in CM or DM. All cultures were harvested following LPS challenge for 48 h and 72 h. LPS induced transcription of Interleukin 1β (IL-1β), Interleukin -8 (IL-8), Toll like receptor 3 (TLR3), interferon regulating factor 3 (irf3), Nuclear factor ĸβ (NFĸβ), one of the multidrug transporters, ABCC2, and glutamine synthase 1 (GLS01) in RTgutGC cells at one or both sampling points (48 h and/or 72 h post LPS challenge). RNA from baker's yeast in culture alone, (cultured 120 h and 144 h with RTgutGC cells and harvested at the respective LPS sampling points) induced transcription of INF1, TNFα and ticam/trif, not induced by LPS. In addition, RNA from baker's yeast affected IL-1β, TLR3, irf3 and NFĸβ, comparable to the responses triggered by LPS. RNA from baker's yeast alone did not affect ABCC2 or GLS01 transcriptions in this set up. So, LPS and RNA from baker's yeast affects distinct but also common gene transcripts in this intestinal cell line. Culturing RTgutGC cells in DM, adding a combination of LPS and RNA from baker's yeast, reduced IL-1β transcription compared to cells grown in CM, 48 h and 72 h post LPS challenge. Also, in RTgutGC cells, grown in DM, the LPS induced transcription of ABCC2 declined, measured 48 h post LPS challenge. Possibly indicating that optimal transcription of IL-1β and ABBC2 in RTgutGC cells, cultured over time, requires access of adequate nutrients under stressful condition. RNA from baker's yeast induced INF1 transcription in the RTgutGC cells, regardless if the medium was complete or deprived of nutrients. However, culturing RTgutGC cells in DM enriched with RNA from baker's yeast for a longer period of time (120 h, 144 h), seemed beneficial for INF1 transcription.
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