Lupus may be linked to gut flora imbalance

Could the development of lupus be caused by an imbalance in the gut microbiota? This is according to new work carried out by the NYU School of Medicine, in New York, and published online this Tuesday, February 19 in the Annals of rheumatic diseases.

A chronic autoimmune disease, systemic lupus erythematosus (SLE) is said to be “systemic”, that is to say that it can affect any part of the body. Appearing in flare-ups, it is due to a dysregulation of the immune system: while they are supposed to defend our body against external and internal attacks, the lymphocytes have an abnormal activity in people affected by lupus which leads to an attack on all the organs of our body: the skin, the joints, the kidneys, the heart, the brain… Due to this wide variety of possible damage, the expression of the disease is different for each individual. It can be exclusively cutaneous (without any risk of subsequent damage to a vital organ), or more diffuse by affecting several organs, which can lead to severe damage if the disease is not well treated.

The bacterium Ruminococcus gnavus in question

This is the first study to clearly shed light on the role of gut bacterial imbalances in the development of life-threatening forms of lupus.

The cause: an intestinal bacterium called Ruminococcus gnavus. By analyzing the microbiota of 61 women diagnosed with SLE, the researchers found that this bacterium was five times more present in their intestinal flora than in that of the 17 women of the same age and racial origin who were part of the group. witness.

The study results also showed that disease “flare-ups”, which can manifest as skin rashes, joint pain or severe kidney dysfunction, closely follow major increases in bacteria growth Ruminococcus gnavus in the gut, as well as the presence in blood samples of antibodies specifically designed to bind to the bacteria. Study participants with kidney dysfunction had particularly high levels of antibodies against R. gnavus.

“Our study strongly suggests that, in some patients, bacterial imbalances may underlie lupus and associated disease flares,” says Gregg Silverman, immunologist and lead author of the study. “Our results also indicate that leakage of bacteria from the gut is a possible immune system trigger of disease and suggest that the internal gut environment may therefore play a more critical role than genetics in kidney flares of this disease. too often fatal,” he continues. He also says he suspects antibodies to R. gnavus to provoke a “continuous and relentless” immune attack on the organs involved in the flare-ups.

A new therapeutic approach to lupus

This new discovery could allow the development of relatively simple blood tests to detect antibodies against the gut bacteria involved. These tests could also be used to diagnose and monitor the progression and treatment of lupus, even in the early stages of the disease. “Current tests are often inconclusive and rely on signs and symptoms that only appear after the disease has already progressed,” Dr. Silverman said.

Pending the development of such tests, further work is needed to confirm that the bacterium R. gnavus is implicated in the development of lupus. If this is true, it could result in therapeutic changes to not only relieve symptoms, but also limit flare-ups.