Link Found Between Rheumatoid Arthritis Drug and Flesh-Eating Infection

In a recent study, researchers discovered that patients with rheumatoid arthritis taking drugs that inhibit interleukin-1beta (IL-1beta) are significantly more likely to develop invasive Group A Streptococcal infections.

Patients receiving this treatment were 300 times as likely to develop the flesh-eating infection compared with patients receiving other treatments, according to a study published by Science Immunology.

“The more we know about each step in the body's immune response to bacterial infections, the better equipped we are to design more personalized, targeted therapies for autoimmune diseases, therapies that are effective, but minimize risk of infection,” said senior author Victor Nizet, MD.

IL-1beta elicits an immune response, and causes white blood cells to clear the site of an infection. The body initially creates the molecule in a longer, inactive form, which must be cleaved to be activated, according to the study.

It was previously thought that the body itself was only able to cleave and activate IL-1beta. Researchers discovered that SpeB, an enzyme secreted by strep bacteria, can also do the same.

“This finding may explain why some of the more invasive, flesh-eating strep strains have a genetic mutation that blocks SpeB production - it helps them avoid tripping the alarm and setting off an immune response," said first author Christopher LaRock, PhD.”

The researchers hypothesized that for less invasive strains of the bacteria, this would allow for the strep bacteria to gain footing while eliminating other bacteria. In the study, they searched the FDA’s database on adverse events relating to anakinra, a drug that inhibits IL-1beta.

It was found that these patients were 300 times more likely to develop flesh-eating strep infections, according to the study.

“A likely explanation for this increased risk is that with IL-1beta out of the picture, as is the case with patients taking anakinra, strep strains can progress to invasive infection even while producing SpeB, which goes unnoticed by the immune system,” Dr LaRock said.

Researchers believe that their findings show the importance of IL-1beta as an early warning system. Without it, infections can go unnoticed and develop into serious problems.

“Inhibiting the body's bacterial sensor can put a person at risk for invasive infection but just the fact that we now know that this patient population is at higher risk and why means we can take simple steps -- such as close monitoring and prophylactic antibiotics -- to prevent it from happening,” Dr Nizet concluded.