While scientists were searching for blood-based biomarkers that could predict rheumatoid arthritis flare-ups, they stumbled upon a never-before-seen type of cell – dubbed PRIME cells. Seven days before the flare, these cells were spotted accumulating in the bloodstream, but oddly they vanished during the flare.
The study, published in The New England Journal of Medicine, recruited four subjects that suffered from rheumatoid arthritis and assigned them with collecting finger-prick blood samples every week for four years. In addition to blood samples, the participants tracked flare-ups and personal symptoms so that the researchers could determine any association between blood markers and disease activity.
As the team examined RNA expression in the blood samples, they saw a pattern in all the subjects about seven days before flare-ups. A cell with an RNA profile not seen in immune cells or blood that resembles synovial fibroblasts, which is a cell found in joints and not freely flowing in the bloodstream. They called the newly discovered cells PRIME cells, which means PRe-Inflammation MEsenchymal cells.
Dana Orange, a co-author on the study, said:
That got us thinking there was something fishy going on. We were so surprised to see that the genes expressed right before a flare are normally active in the bone, muscle, and extracellular matrix–strange pathways to find in blood cells.
The researchers then tested 19 additional rheumatoid arthritis subjects to verify whether these PRIME cells do, in fact, appear in the days before an acute flare-up.
Interestingly, these PRIME cells vanished from the bloodstream at the start of a flare-up. This behavior has led the team to come up with a theory that the PRIME cells migrate from the blood into the joint’s membranes and cause the rheumatoid arthritis flare-ups.
There is still much research and trials to be done. Regardless, the potential implications of this new cell discovery are substantial.
Robert Darnell, whose lab led the new research, explained:
PRIME cells are one thing you might want to target to arrest the flare before it happens. That’s the ideal of medical science – to know enough about a disease that you can put your finger on what’s about to make someone sick. If these cells are the antecedents to joint sickness, they become a potential target for new drugs.
The discovery could pave the way for simple testing devices that help arthritis patients better predict an oncoming flare-up and new treatments to prevent the flare-ups from even starting.
