In the study, researchers found that 61 women diagnosed with lupus had higher amounts of a gut bacterium known as Ruminococcus gnavus, compared to 17 healthy women.
The bacterium was also present in healthy women, but at much lower levels.
“The results showed that lupus patients have gut microbiome patterns different from healthy individuals, and these changes correlated with disease activity,” said Jessy Alexander, PhD, a research professor in the department of medicine at the University at Buffalo, who was not involved in the study.
The paper was published February 19 in the Annals of the Rheumatic Diseases.
Most people with lupus have times when their disease is mostly quiet, known as a remission. In between, symptoms can increase, or “flare.”
The study found that R. gnavus levels increased in the gut during flares. Blood tests also showed a rise in antibodies — immune proteins — that bind to the bacterium during these times.
Alexander said “the antibodies generated by the patient against this bacteria was directly proportional to the severity of the disease.”
The authors of the paper caution that their results can’t show whether the overgrowth of R. gnavus causes or triggers lupus, or if disease flares allow the bacterium to thrive in the gut.
Dr. Martin Kriegel, PhD, an assistant professor of immunobiology and rheumatology at Yale School of Medicine, who was not involved in the study, said it’s likely a “two-way street.”
Alexander said the study strengthens the idea “that gut bacteria affect the disease lupus, and opens the door to developing prognostic tests that reveal the disease status of the lupus nephritis patient.”
“However, a lot more work remains to be done,” she added.