Background Imbalance and disfuntion in regulatory T-cells (Tregs) and IL-17 producer lymphocytes (Th17) have been implicated in the pathogenesis of rheumatoid arthritis (RA). Gray scale synovial proliferation (GS), power Doppler signal (pD) and bone erosions seen on high resolution muskuloskeletal ultrasound (MSUS) are hallmarks of destructive articular disease.
Objectives The present study was undertaken to evaluate the association of peripheral Tregs and Th17 with MSUS findings in RA.
Methods 90 RA patients (1987 ACR criteria) treated with disease-modifying antirheumatic drugs (DMARDs) were included in this prospective cross-sectional study. A blood sample was taken just before clinical and ultrasonographic evaluation. Lymphocytes were isolated and immunophenotyped by flow cytometry to investigate regulatory FoxP3+ T cells and IL-17+ cells. MSUS (MyLab 60, Esaote, Genova, Italy, linear probe 6–18 MHz) was performed consecutively by two ultrassound-trained rheumatologists on the wrists, 2th and 3th metacarpophalangeal and 2th and 3th proximal interphalangeal joints of both hands. GS and pD were searched using a semi-quantitative scale (0–3). Bone erosions were classified as present or absent. The sum of the individual joint scores for GS and pD (score 10) was calculated and used to correlate with clinical and laboratory data. Disease acitivity and disability were measured using Disease Activity Score in 28 joints (DAS28) and Health Assessment Questionnaire (HAQ), respectively. Mann-Whitney test, Kruskal-Wallis test and Spearman correlation coefficient (rS) were used for statistical analysis. Inter-rater agreement was tested using the weighted kappa statistic (WKS) and intraclass correlation (ICC).
Results Clinical and demographic features were: mean age, 55.8 ±11 years; female gender, 79%; Caucasians, 84%; positive rheumatoid factor by nephelometry, 63%; median (interquartile range) disease duration 6 (2–13) years; mean ± SD DAS28, 4.28±1.64; mean ± SD HAQ score, 1.11±0.85. WKS for erosions was 1, and ICC for GS- and pD-score10 were 0.964 (95%CI 0.899 to 0.986) and 0.859 (0.646 to 0.941), respectively. There was no significant association of bone erosions, GS- and pD-score10 with peripheral Tregs and Th17 cells (P>0.25 for all tests). Tregs but not Th17 cells were significantly associated with DAS28 level of disease activity (figure 1).
Conclusions In this first study addressing MSUS features and lymphocytes subtypes in established RA, data did not support an association of circulating Tregs and Th17 lymphocytes with inflammatory and structural damage findings on MSUS.
Disclosure of Interest None declared