Distinct Fluorescence Optical Imaging Patient Clusters Emerge for Seropositive and Seronegative Rheumatoid Arthritis.

Area of Science:

• Rheumatology
• Medical Imaging
• Biotechnology

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation.
• Accurate phenotyping of RA is crucial for effective treatment strategies.
• Current diagnostic methods may not fully capture the heterogeneity of RA inflammation.

Purpose of the Study:

• To investigate the utility of digital activity fluorescence optical imaging (FOI) in identifying distinct rheumatoid arthritis (RA) phenotypes.
• To determine if FOI patterns of inflammation can differentiate RA patient subgroups.

Main Methods:

• Newly diagnosed RA patients underwent clinical examination, musculoskeletal ultrasound, and FOI.
• Inflammation on FOI was assessed by capillary leakage and/or fluorophore perfusion.
• Digital disease activity (DACT) scores were calculated using computerized algorithms, and unsupervised clustering identified patient subgroups based on FOI patterns relative to autoantibodies (ACPA, RF).

Main Results:

• Of 1326 hand joints in 39 RA patients, 400 (30%) showed inflammation by FOI; 95% had DACT-FOI scores >1.
• Unsupervised analysis revealed two distinct patient clusters: Cluster 1 (n=29) with a higher proportion of seropositive patients and Cluster 2 (n=10) with higher C-reactive-protein levels.
• Cluster 2 exhibited a wider distribution of inflamed joints compared to Cluster 1, which showed inflammation concentrated around specific wrist and metacarpophalangeal joints. DACT scores were significantly higher in Cluster 2.

Conclusions:

• Fluorescence optical imaging (FOI)-based digital quantification of hand joint inflammation can reveal two distinct RA subpopulations.
• These subpopulations correlate with the presence or absence of specific autoantibodies (ACPA and RF).
• FOI offers a novel approach to phenotyping RA, potentially guiding personalized treatment decisions.