Why is biologic therapy useful in spondyloarthritis? Knowledge from synovial immunopathologic studies of spondyloarthritis

Efficacy of TNF-α Inhibitors in the Treatment of nr-axSpA: A Systematic Review and Meta-Analysis Based on Randomized Controlled Trials

INTRODUCTION

A growing number of randomized controlled trials (RCTs) have demonstrated the effectiveness of tumor necrosis factor-α (TNF-α) inhibitors in treating non-radiographic axial spondyloarthritis (nr-axSpA). This study aimed to evaluate the efficacy of TNF-α inhibitors in the treatment of nr-axSpA.

METHODS

PubMed, EMBASE, Web of Science, and the Cochrane Library databases were systematically searched for relevant RCTs using specific keywords up to June 2023. The primary outcome was the proportion of patients who achieved Assessment in SpondyloArthritis international Society 40% (ASAS40). Secondary outcomes included ASAS20, Bath Ankylosing Spondylitis Disease Activity Index 50% (BASDAI50), ASAS partial remission, and ASAS5/6.

RESULTS

A total of eight RCTs involving 1,376 patients were included. Patients receiving anti-TNF therapy exhibited a higher rate of ASAS40 (pooled RR = 2.36; 95% CI: 1.63-3.42; p < 0.001). In addition, the TNF-α inhibitor group showed higher BASDAI50 rates (pooled RR = 2.06; 95% CI: 1.48-2.89), ASAS20 rates (pooled RR = 1.48; 95% CI: 1.31-1.67), ASAS partial remission rates (pooled RR = 2.33; 95% CI: 1.58-3.43), and ASAS5/6 rates (RR = 3.46; 95% CI: 2.05-5.83) than the placebo group.

CONCLUSION

The TNF-α inhibitors were effective in treating nr-axSpA.

Caspase-1 level in synovial fluid is high in patients with spondyloarthropathy but not in patients with gout

Activation of caspase-1 by NALP3 inflammasomes has been shown to be important in initiating acute gouty arthritis. The objectives of this study were to measure the levels of caspase-1 in synovial fluid in gout and various arthritides, and to elucidate the clinical significance of caspase-1 levels in synovial fluid. Caspase-1, IL-1β, IL-18, and uric acid were measured in synovial fluid from 112 patients with gout and other arthritides, such as rheumatoid arthritis, osteoarthritis, and spondyloarthropathy. Caspase-1 in synovial fluid from patients with crystal-induced arthritis, inflammatory arthritis, osteoarthritis, and spondyloarthropathy was 35.9 ± 86.7, 49.7 ± 107.7, 2.1 ± 7.0, and 152.6 ± 155.7 pg/mL, respectively. The mean level and the frequency of high levels (≥125 pg/mL) of caspase-1 in spondyloarthropathy were significantly higher than those in the other arthritides including gout. Caspase-1 was detectible in the synovial fluid of patients with the various arthritides. Contrary to our hypothesis, the caspase-1 level in the synovial fluid of patients with gout was not higher than in that of other arthritides. High levels of caspase-1 may be helpful in differentiating spondyloarthropathy from other arthritides.