Cysteine Amino Acid Aids Gut Healing in Mice, MIT Study Finds

Massachusetts Institute of Technology (MIT) researchers have identified that cysteine, an amino acid, can help the intestine repair itself after damage. The study, conducted in mice, showed that cysteine activates immune cells. These cells then boost intestinal stem cells, which helps regenerate tissue in the small intestine.

This discovery could lead to new methods for reducing intestinal damage. Such damage is often caused by radiation therapy and chemotherapy. Cysteine-rich diets or supplements might help cancer patients recover faster from treatment-related injuries. The study was published in *Nature*.

Researchers fed mice diets enriched with one of twenty different amino acids. Cysteine produced the strongest regenerative effect on both stem cells and progenitor cells. Progenitor cells mature into adult intestinal cells. Intestinal cells absorb cysteine from food and convert it into a molecule called CoA. This molecule is then released into the intestinal lining.

Immune cells, specifically CD8 T cells, absorb CoA. Once activated, these T cells multiply and produce Interleukin-22 (IL-22). IL-22 is a signaling protein that plays a significant role in intestinal repair and stem cell regeneration. These activated T cells gather in the small intestine's lining, positioning them to respond quickly to damage. The effect was primarily observed in the small intestine because most dietary protein is absorbed there.

Mice on a cysteine-rich diet showed improved recovery from radiation-related intestinal damage. Similar regenerative benefits were observed in unpublished experiments involving the chemotherapy drug 5-fluorouracil. Cysteine is present in many high-protein foods, including meat, dairy products, legumes, and nuts. The human body can also produce cysteine from another amino acid, methionine.

Dietary cysteine appears to have a stronger effect on the intestine. This is because it reaches the gut directly before being distributed throughout the body. The MIT team is now investigating if cysteine can support regeneration in other tissues. They are also exploring the effects of other amino acids on stem cell behavior.