Hydrogen sulfide present in rotten eggs plays an important role in autoimmune disease. Our immune system contains a built-in brake in the form of regulatory T cells, or Tregs.
These Tregs ensure that inflammatory responses don't get out of hand and do damage. In autoimmune diseases, sometimes these Treg cells don't act as they should. Songtao Shi of the University of Pennsylvania said that H2S was very interesting, adding that high levels of the gas were toxic, but our body maintains it at a certain level and our cells produce it.
In a series of experiments, Shi and his team observed that mice with reduced H2S production had large numbers of methyl groups on the Foxp3 gene, tags which repress the gene's expression. The team's work revealed that H2S regulates the expression of Tet1 and Tet2 by modifying a transcription factor called NFYB by adding a sulfur atom to it, a process called sulfhydration.
Reducing H2S levels led to reduced expression of Tet1 and Tet2 in T cells and, consequently, impaired function and development of Tregs. Again, the researchers showed they could partially reverse these effects by adding back a source of H2S. Shi concluded that it was clear that H2S has a very important role to play in immune regulation.
The study is published in the journal Immunity.