FAQ: How is calprotectin useful in clinical assessment of rheumatoid arthritis?
20. May 2021 |
11 min read
Calprotectin, a biomarker for neutrophil activation and inflammation, has been shown to have clinical diagnostic value in assessment of disease activity in rheumatoid arthritis (RA), including the potential to monitor the treatment response.
Why does calprotectin levels reflect the joint inflammatory activity directly?
During inflammation, neutrophils migrate to the inflammatory site and secrete large amounts of calprotectin, which act as a soluble proinflammatory mediator1. Calprotectin is released locally at inflammation sites, including inflamed synovium, and enters the systemic circulation where it can be measured. Since calprotectin is released predominantly from locally activated leukocytes at the sites of joint inflammation, it directly reflects joint inflammatory activity2,3.
Can calprotectin in blood monitor disease activity in RA?
Since the concentration of calprotectin reflects the degree of inflammation and correlates with clinical scores4-6, it is a good diagnostic tool and can provide valuable monitoring of the disease activity, treatment response and relapse 3,7,8.
Furthermore, since circulating calprotectin is elevated in active disease and decreases after effective treatment it has shown to be a more sensitive biomarker of disease activity in RA than conventionally used acute-phase proteins8-16.
Calprotectin levels correlate with multiple disease scores and increase with disease severity.
(Figure from Inciarte-Mundo J, et al. Arthritis Care & Research. 2016 (10). Calprotectin serum levels in RA patients according to disease status using the Disease Activity Score in 28 joints (DAS28), the Clinical Disease Activity Index (CDAI), and the Simplified Disease Activity Index (SDAI).)
How does calprotectin compare to other inflammatory markers in RA?
Calprotectin levels correlates with levels of other classically used inflammation markers, like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)17-19. However, calprotectin may be more effective than ESR and CRP to gauge disease activity, as it has been demonstrated that more than 40 % of RA patients have normal ESR or CRP20. Calprotectin can potentially be a useful inflammatory marker for these patients as it has shown diagnostic value in patients with normal/low CRP levels21-23.