Gut Microbes May Impact Autoimmunity

Researchers show that the prevalence of one genus of bacteria correlates with the onset of rheumatoid arthritis.

Nov 6, 2013
Abby Olena

PrevotellaBMC MICROBIOLOGY, YAMANAKA ET AL.The more scientists learn about the gut microbiome, the more roles it seems to play. New evidence from researchers at the New York University (NYU) School of Medicine, the Memorial Sloan-Kettering Cancer Center in New York, and the Harvard School of Public Health in Cambridge, Massachusetts, shows a correlation between onset of rheumatoid arthritis (RA) with the prevalence of a certain microbe—Prevotella copri. The work was published this week (November 5) in eLife.

“It's been suspected for years and years . . . that the development of autoimmune diseases like arthritis is dependent on the gut microbiota,” Diane Mathis, a professor of microbiology and immunobiology at Harvard Medical School in Boston, Massachusetts, who was not involved in the work, told ScienceNOW. “It’s a very striking finding,” she added.

The researchers sequenced bacterial genes in 114 fecal samples from patients who had recently been diagnosed with RA, patients who had been treated for RA, patients with a different type of autoimmune arthritis (psoriatic), and healthy controls. They found P. copri in 75 percent of the samples from patients who had just been diagnosed with RA, but only in 21 percent of samples from healthy controls, 38 percent of samples from patients with psoriatic arthritis, and in less than 12 percent of samples from patients who had been treated for RA. Then the researchers compared P. copri DNA from several of the samples from newly diagnosed RA patients and controls and found that P. copri strains from recent-onset RA patients had fewer genes to metabolize purines and vitamins. The team also inoculated mice with P. copri and showed that the bacteria not only colonized their guts, but also seemed to make the rodents more susceptible to inflammation.

“That they were able to associate one bacterium with one pathology is remarkable,” immunologist Yasmine Belkaid of National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, who did not participate in the work, told ScienceNOW.

“At this stage, however, we cannot conclude that there is a causal link between the abundance of P. copri and the onset of rheumatoid arthritis,” coauthor Dan Littman, a professor of immunology at NYU Langone Medical Center, said in a statement. “We are developing new tools that will hopefully allow us to ask if this is indeed the case.”