Circulating cold-inducible RNA-binding protein levels in microscopic polyangiitis and granulomatosis with polyangiitis : Correlation with disease activity.

OBJECTIVE

This study investigated whether circulating cold-inducible RNA-binding protein (CIRP) could be a biomarker to reflect the current activity, function, and damage status in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA).

METHODS

This study selected 39 MPA and 26 GPA patients. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV)-specific indices include the Birmingham Vasculitis Activity Index (BVAS), five-factor score (FFS), the Korean version of the Short-Form 36-Item Health Survey (SF-36) physical component summary (PCS) and mental component summary (MCS), and the vasculitis damage index (VDI). The highest tertile of BVAS was defined as high activity of AAV.

RESULTS

The median age of the study subjects was 65.0 years and 53.8% were women. The median BVAS, FFS, SF-36 PCS, MCS, and VDI scores were 12.0, 2.0, 47.5, 50.3, and 3.0, respectively. The median circulating CIRP level was 6.4 ng/mL. Among the four AAV-specific indices, circulating CIRP was significantly correlated with BVAS (r = 0.256). Using the receiver operator characteristic curve, the cut-off of circulating CIRP for high activity of AAV was 6.16 ng/mL. High activity of AAV was identified more frequently in patients with circulating CIRP ≥ 6.16 ng/mL than in those with circulating CIRP < 6.16 ng/mL (48.6% vs. 21.4%). In addition, patients with circulating CIRP ≥ 6.16 ng/mL exhibited a significantly higher risk for high activity of AAV than those with circulating CIRP < 6.16 ng/mL (relative risk 3.474).

CONCLUSION

This study suggests the clinical potential of circulating CIRP as a biomarker for reflecting the current BVAS and predicting high activity of AAV in patients with MPA and GPA.