Might Gut Bacteria Help Treat Autoimmune and Allergic Diseases?

Anthony L. Komaroff, MD

Multiple nonpathogenic Clostridia species attenuated disease severity in mice.

T regulatory (Treg) lymphocytes play a central role in quieting the immune response in autoimmune diseases. Because many Treg lymphocytes are produced by the gut immune system, researchers are exploring ways to boost the number of these Treg cells to treat patients with autoimmune diseases.

Some species of bacteria that are normal gut flora in mice increase the number of Treg cells. A Japanese team tested the ability of different human gut bacterial species to induce Treg cells in germ-free mice. They identified 17 Clostridia strains that produced the desired effect; inoculating the germ-free mice with all 17 strains simultaneously produced the largest boost. The function (anti-inflammatory cytokine production), as well as the number, of Treg cells rose. The 17 identified Clostridia strains did not produce toxins (as is the case with pathogenic human Clostridia strains). The investigators then demonstrated that adding these bacteria to the guts of mice with experimentally induced severe allergic diseases greatly attenuated their severity.

Citation(s):

Atarashi K et al. Treg induction by a rationally selected mixture of Clostridia strains from the human microbiota. Nature 2013 Aug 8; 500:232.