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Levels of circulating cellular fibronectin are increased in patients with rheumatoid vasculitis
A E Voskuyl1, J J Emeis, J M Hazes
1Department of Rheumatology, Leiden University Medical Center, The Netherlands.
Insights
Serum levels of circulating cellular fibronectin (cFN) are elevated in rheumatoid arthritis (RA) patients, especially those with vasculitis. This finding may aid in diagnosing RA complications.
Area of Science:
- Rheumatology
- Immunology
- Biochemistry
Background:
- Rheumatoid arthritis (RA) is a chronic autoimmune disease.
- Vasculitis can be a severe complication of RA.
- Biomarkers for RA vasculitis are needed.
Purpose of the Study:
- To determine if serum levels of circulating cellular fibronectin (cFN) are elevated in RA patients with vasculitis.
- To compare cFN levels in RA patients with vasculitis to those with other RA manifestations and other autoimmune diseases.
Main Methods:
- Serum cFN levels were measured using ELISA in patients with RA and vasculitis (RV), RA with extraarticular manifestations (RA+), uncomplicated RA (RA-), systemic lupus erythematosus (SLE), and Crohn's disease (CD).
- Healthy young (yHC) and elderly (eHC) controls were included for comparison.
- Plasma cFN and von Willebrand factor antigen levels were also assessed in RA patients.
Main Results:
- RV patients showed significantly higher serum cFN levels compared to RA+, RA-, SLE, CD, yHC, and eHC groups.
- Elevated cFN levels were also observed in RA+ patients compared to eHC.
- The cFN ELISA demonstrated 90% sensitivity and 46% specificity in distinguishing RV patients from RA+ patients.
Conclusions:
- Serum cFN levels are increased in RA patients.
- Elevated cFN is particularly frequent in RA patients with vasculitis.
- cFN may serve as a potential biomarker for RA-associated vasculitis.
Objective:
To investigate whether serum levels of circulating cellular fibronectin (cFN) are increased in patients with rheumatoid arthritis (RA) complicated by vasculitis.
Methods:
Levels of serum cFN were determined by an enzyme-linked immunosorbent assay (ELISA) in 26 RA patients with histologically proven vasculitis of recent onset (RV) and were compared to the levels in 47 RA patients with extraarticular manifestations of recent onset but no histological evidence of vasculitis (RA+), 43 patients with uncomplicated RA (RA-), 16 patients with systemic lupus erythematosus and active disease (SLE), 30 patients with active Crohn's disease (CD), 21 young healthy controls (yHC) and 17 elderly healthy controls (eHC). Plasma levels of cFN and von Willebrand factor antigen were also determined in the RA patients.
Results:
In RV patients, the median cFN level was significantly (P = 0.01) higher compared to that of RA+ patients, and was also significantly (P < 0.0000) higher compared to the cFN level in the RA-, SLE, CD, yHC and eHC groups. When compared to eHC, the cFN level was significantly higher in RA+ (P = 0.008); it was also higher in RA-, although not significantly (P = 0.42). 77% of the RV patients, 55% of the RA+ patients, and 37% of the RA-patients had a cFN level > 2 SD above the mean level for eHC. At an optimal cut-off titre the sensitivity of the cFN ELISA in discriminating RV patients from RA+ patients was 90%, the specificity was 46% and the accuracy was 68%. Plasma levels of cFN correlated significantly (r = 0.62; P < 0.001) with the von Willebrand factor antigen levels.
Conclusions:
Increased levels of serum cFN are present in patients with RA, and are frequently found in RA patients with extraarticular manifestations, particularly in those with vasculitis.