Rheumatoid arthritis is the most common inflammatory joint disease of autoimmune origin. We now know how to identify the most dangerous shapes for the joints.
In rheumatoid arthritis, a new technique, developed by a Swedish research team, makes it possible to better analyze which autoimmune processes actually take place inside an inflammatory joint.
This discovery will make it possible to determine which patients are most at risk of joint destruction in order to apply the most effective therapeutic strategies to them from the outset and to prevent these lesions. This study is published in Annals of the Rheumatic Diseases.
Rheumatoid arthritis: a heterogeneous disease
Rheumatoid arthritis is a chronic inflammatory disease of the joints that is autoimmune in origin.
It is accompanied, in approximately two thirds of patients, by specific antibodies which are directed against various fragments of proteins which are found naturally in the body, the citrullinated proteins (fillagrin, α-enolase, vimentin, collagen type II, fibrinogen and histones …). These “autoantibodies” are called anti-citrullinated protein antibodies or ACPA.
Research has shown genetic differences between patients who have ACPAs and those who do not. In addition, the onset of polyarthritis with ACPA is strongly associated with smoking, which is not the case in RA who do not have ACPA.
Thus rheumatoid arthritis with or without ACPA represents 2 different inflammatory joint diseases, with distinct joint prognoses, but which begin with an identical clinical picture. This complicates the choice of treatment, especially since not all polyarthritis with ACPA is aggressive.
Earlier diagnosis of polyarthritis at risk
ACPA autoantibodies simplify the diagnosis of rheumatoid arthritis when they are present at the onset of the disease, but they also have a prognostic role since they are more often associated with more intense inflammation, more severe course and destruction. more frequent joints.
Until now, we did not understand why and especially what rate or what type of ACPA was the most dangerous. The study reveals that the level of ACPA is lower in joint fluid than in blood and that it is not the level of ACPA in synovial fluid or in blood that is correlated with joint risk.
This would rather be dependent on the mixture of ACPA of different types in the joint: it is under these conditions of “polyclonality” that this mixture of ACPA would form aggregates of antibodies, the “immune complexes”, in the same way. to trigger intense joint inflammation which leads to destruction of cartilage and joint.
This is a real revolution. With this new method, the Swedish team was able to show that, in rheumatoid arthritis with ACPA, this mixture of antibodies has a direct role in joint destruction. Above all, it is now possible to identify patients at risk in order to implement more quickly the treatments that will prevent any joint destruction.
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