Both of these papers were published in Nature late last year and show the importance of short chain fatty acids (SCFAs), in particular butyrate (a type of SCFA), in the induction of regulatory T cells (Tregs, discussed before, cells that help prevent inflammation/colitis). SCFAs are produced by bacteria when fibre is broken down by bacteria in the colon.
The two papers use different methods but are remarkably similar in what they demonstrate. Both papers remind us that commensal bacteria (the healthy bugs that appear in the gut which have often been discussed in this blog before) are important for producing Tregs. They both show that the production of SCFA, in particular butyrate, was necessary for producing Tregs. They showed this in both cells in the test tube, and also in mice. Both papers went on to show that the Treg effect was likely made by butyrate effecting gene expression in T cells, a so-called “epigenetic” effect. In one of the papers they also showed that in a mouse model of colitis, providing a diet that would increase butyrate levels could reduce the severity of colitis.
These findings are consistent with butyrate being used as an enema to treat colitis in IBD. However, this treatment is very difficult to administer for a variety of reasons and the main purpose of these papers is really to look at a possible mechanism of how our healthy gut bacteria can affect our immune system.