Defects in the T cells cause autoimmune disease and inflammation as they affect the gut bacteria. According to recent research, restoring inosine, an essential metabolite, or replacing the destroyed gut bacteria could help to treat children with the IPEX syndrome, often fatal and rare autoimmune disease.

The regulatory T cells in the body prevent the immune system from mistakenly attacking the body’s tissues. Therefore, defects in these cells lead to autoimmune diseases. For instance, the IPEX syndrome is caused by a disruption of the function of the T cells due to a mutation in one transcription factor. This syndrome is characterized by different inflammatory problems, including serious enteropathy, type 1 diabetes and eczema. Children with this syndrome die before they are 2 if there is no suitable cell transplant donor.

Changes in the gut microbiome can also cause an autoimmune disease. The gut microbiome consists of the bacteria that are found in the gastrointestinal system. According to a study carried out on mice, the mice showed the autoimmune symptoms around the same time when they showed changes in the gastrointestinal microbiome. These mice carried a mutant version of the Foxp3. To be more accurate, the mice had fewer bacteria from the genus called Lactobacillus. The researchers were able to restore the mice’s gut microbiome by feeding the animals with Lactobacillus reuteri. With this, they reduced the inflammation levels and extended the lives of the mice.

The gut bacteria present in the body affect the organism tremendously by secreting metabolic molecules. The mice without Foxp3 lacked the metabolite inosine. However, the levels of this metabolite were brought back to normal after feeding the mice with the Lactobacillus reuteri. The scientists found out that the metabolite inosine prevents the production of Th1 cells, as well as Th2 cells, if adenosine A2A receptors, cell surface proteins, are bund. In the mice, these Th1 and Th2 cells, pro-inflammatory cells, were elevated. However, the treatment with inosine or Lactobacillus reuteri reduced the number of the cells, the inflammation and extended the lifespan of the mice.

According to the researchers, their discovery shows that inosine, Lactobacillus reuteri or some other A2A receptors, could be used as a treatment for controlling autoimmune diseases, like the IPEX syndrome.