S100A8/A9 as a biomarker for synovial inflammation and joint damage in patients with rheumatoid arthritis

S100A8 and S100A9 are major leukocyte proteins, known as damage-associated molecular patterns, found at high concentrations in the synovial fluid of patients with rheumatoid arthritis (RA). A heterodimeric complex of S100A8/A9 is secreted by activated leukocytes and binds to Toll-like receptor 4, which mediates downstream signaling and promotes inflammation and autoimmunity. Serum and synovial fluid levels of S100A8/A9 are markedly higher in patients with RA than in patients with osteoarthritis or miscellaneous inflammatory arthritis. Serum levels of S100A8/A9 are significantly correlated with clinical and laboratory markers of inflammation, such as C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and the Disease Activity Score for 28 joints. Significant correlations have also been found between S100A8/A9 and radiographic and clinical assessments of joint damage, such as hand radiographs and the Rheumatoid Arthritis Articular Damage score. In addition, among known inflammatory markers, S100A8/A9 has the strongest correlation with total sum scores of ultrasonography assessment. Furthermore, baseline levels of S100A8/A9 are independently associated with progression of joint destruction in longitudinal studies and are responsive to change during conventional and biologic treatments. These findings suggest S100A8/A9 to be a valuable diagnostic and prognostic biomarker for RA.

Correlation of myeloid related proteins [MRP8/MRP14] and disease activity in juvenile rheumatoid arthritis

To evaluate the expression of myeloid related proteins MRP8/MRP14 in the serum and synovial fluid of JRA and their correlation with local and systemic parameters of disease activity. Thirty JRA patients [Group I], and ten controls [Group II] were included in the study. The patients were subjected to thorough history taking and clinical examination. Synovial fluid aspiration was done from ten JRA patients. Laporatory investigations included CBC, ESR, RE, ASO, ANA, CRP, ALT, urine analysis and synovial fluid analysis for white blood cell count [SF-WBCs], lymphocytes%, and acute phase serum amyloid. MRP8/MRP14 was assessed with ELISA technique in serum and synovial fluid samples. Serum level of MRP8/MRP14 was elevated in Group I in comparison to up II. The serum and synovial levels of MRP8/MRP14 in Group I showed no significant inter-correlation. The MRP8/MRP14 in group I showed significant positive correlation with ESR, CRP, DAS, and A-SAA. The SF MRP8/MRP14 in group I showed positive significant correlation with SF-WBCs and A-SAA. The elevated MRP8/MRP14 in the serum and synovial fluids of patients with JRA showed a significant correlation with local and systemic disease activity parameters. So, it can be used to monitor disease activity and patient's response to treatment