Animal study explores how fermented foods influence gene responses in the colon

In this study, Canadian researchers elucidated the role of two different sources of fermentable material (FM), fructooligosaccharides (FOS) and wheat bran (WB), on the expression of genes involved in short-chain fatty acid (SCFA) transport, G-protein signaling, apoptosis, cell proliferation and oncogenesis in colon epithelia of healthy rats. Their findings were published in the journal Nutrition Research.

• The influence of FM source on the luminal concentrations of their end products, colon cell metabolism and disease susceptibility is not well-understood.
• The researchers hypothesized that total fermentation, not the source of FM, is the main factor that determines cellular/molecular outcomes in healthy colon epithelia.
• To test their hypothesis, the researchers first fed rats AIN-93G control (no FM) or experimental diets containing WB (~1, 2 or 5 percent FM) or FOS (~2, 5 or 8 percent FM).
• After six weeks, they assessed the colon mucosa of the rats to quantify the expression of target genes using real-time quantitative polymerase chain reaction.
• The researchers reported that rats fed FOS-based diets showed dose-related changes in the mRNA levels of target genes. These included:
  • Upregulation of three SCFA transporters (Smct2, Mct1 and Mct4) and downregulation of Mct2
  • Upregulation of Gpr109a and downregulation of Gpr120, Gpr43, Gprc5a, Rgs2 and Rgs16
  • Upregulation of apoptosis-related genes (e.g., Bcl2, Bcl2-like 1, Bak1, Caspase 3, Caspase 8 and Caspase 9)
  • Downregulation of oncogenes and metastasis genes (Ros1, Fos, Cd44, Fn1 and Plau)
  • Downregulation of genes involved in cell proliferation (e.g., Hbegf, Hoxb13, Cgref1, Wfdc1, Tgm3, Fgf7, Nov and Lumican).
• In contrast, rats fed WB-based diets showed dose-related upregulation of mRNA levels of Smct2, Rgs16, Gprc5a, Gpr109a, Bcl2-like 1, Caspase 8 and Fos.
• At 2 percent and 5 percent FM, rats fed FOS and WB had different gene expression responses independent of tumor suppressor Tp53 expression.

Based on these findings, the researchers concluded that fermentation alone does not determine gene responses in healthy rat colons.

Journal Reference:

Chen Q, Swist E, Kafenzakis M, Raju J, Brooks SP, Scoggan KA. FRUCTOOLIGOSACCHARIDES AND WHEAT BRAN FED AT SIMILAR FERMENTATION LEVELS DIFFERENTIALLY AFFECT THE EXPRESSION OF GENES INVOLVED IN TRANSPORT, SIGNALING, APOPTOSIS, CELL PROLIFERATION, AND ONCOGENESIS IN THE COLON EPITHELIA OF HEALTHY FISCHER 344 RATS. Nutrition Research. September 2019;69:101–113. DOI: 10.1016/j.nutres.2019.07.006