Transporters and receptors for short-chain fatty acids as the molecular link between colonic bacteria and the host

- The relationship between colonic bacteria and the host is not commensal but mutual.
- Bacterial fermentation products serve as the messengers in this relationship.
- The fermentation products protect against inflammation and cancer in colon.
- SLC5A8 is critical for bacteria-host communication only when fiber intake is low.
- GPR109A and GPR43 are critical for the communication even with optimal fiber intake.

The mutually beneficial relationship between colonic bacteria and the host has been recognized but the molecular aspects of the relationship remain poorly understood. Dietary fiber is critical to this relationship. The short-chain fatty acids acetate, propionate and butyrate, generated by bacterial fermentation of dietary fiber, serve as messengers between colonic bacteria and the host. The beneficial effects of these bacterial metabolites in colon include, but are not limited to, suppression of inflammation and prevention of cancer. Recent studies have identified the plasma membrane transporter SLC5A8 and the cell-surface receptors GPR109A and GPR43 as essential for the biologic effects of short-chain fatty acids in colon. These three proteins coded by the host genome provide the molecular link between colonic bacteria and the host.