In a small study published Wednesday in The New England Journal of Medicine, scientists found that the never-been-seen cell type appeared in patients’ blood a week before their symptoms flared up. The researchers named these cells pre-inflammatory mesenchymal, or PRIME, cells.
For those with the illness, not knowing when a flare will occur is one of the most unsettling aspects of the autoimmune disease, which causes the immune system to attack the body’s own tissue, particularly around the joints.
The new discovery could potentially lead to a future blood test that could warn patients of a coming flare, experts said, though they cautioned that much more research is needed.
Being able to tell a patient and their health care provider that they’re about to get sick is “like a little piece of magic medicine,” said study co-author Dr. Robert Darnell, a Howard Hughes Medical Institute investigator at Rockefeller University in New York City.
PRIME cells could also be a potential target for drugs, as the study researchers believe this cell type may play a role in attacking the healthy tissue.
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“We could figure out a way to block it so it doesn’t get into the joint. And maybe you wouldn’t get a flare then,” Darnell said. “So it has a potential therapeutic value to pursue.”
In the study, four patients sent weekly fingerstick blood samples to the lab over one to four years. The patients also kept a diary documenting their symptoms and visited the clinic once a month.
The researchers sequenced the blood samples to observe gene activity. Using information from the patients’ clinical visits, symptom diaries and blood samples, they found that PRIME cells appeared in the blood one week before a flare. The presence of the cells was also confirmed in blood samples from 19 additional patients. However, these patients didn’t keep symptom diaries, so it’s unclear when the cells appeared relative to a flare-up.
Dr. Diane Horowitz, associate professor of medicine at the Hofstra Northwell School of Medicine in New York, said these findings benefit both scientists and patients.
“As scientists, it helps us to find out the pathway that occurs before a flare, which will help us with flare identification, medication options, treatments, that whole pathway,” said Horowitz, who was not involved with the new study.
The research provides insights into what’s happening on the cellular level that may induce arthritis, Dr. Robert Carter, acting director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, said. “And therefore, once we know about those cells, we can then find ways to develop the treatments that will target them, and prevent the flare.” (Carter was also not involved with the new research.)
How the research pans out “will also be interesting for patients, if there’s a way that they can predict when they’re going to have a flare, and they can treat it earlier and take care of a flare before it actually occurs,” Horowtiz said.
Most rheumatoid arthritis patients are on daily medications such as hydroxychloroquine — which drew attention earlier this year as a potential treatment for COVID-19 — or adalimumab (brand name: Humira), as recommended by the American College of Rheumatology, and take additional drugs when a flare occurs.
One of the most challenging aspects of the disease is not knowing when a flare will arise.
“The hardest thing about being diagnosed with arthritis and living with it is the unexpected,” said rheumatoid arthritis patient Rebecca Gillett, health messaging strategist at The Arthritis Foundation and an occupational therapist.
Still, experts noted that while the new findings are exciting, much more research is needed to fully understand the role PRIME cells play in rheumatoid arthritis. “There’s way more that needs to be done with it before it can become anything clinically applicable for patients in this study,” Horowitz said.
Gillett agreed. “I feel like this is a very promising research study that’s coming out, and the ability to do a broader, more longitudinal study would really make a difference, and give hope, I think for the people living with rheumatoid arthritis like me,” she said.
The team’s next step is to test more patients and confirm if the presence of PRIME cells do foreshadow a flare.
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