Serum Calprotectin as a Novel Biomarker of Disease Severity and Activity in Systemic Sclerosis Patients

A monocentric cross-sectional study was performed to investigate the role of serum calprotectin as a biomarker for disease severity and activity in systemic sclerosis (SSc). Serum calprotectin was measured in 74 consecutive SSc patients admitted to a tertiary hospital in Rome, and in 50 healthy controls (HCs) who were healthcare workers, using Aptiva's particle-based multianalyte technology. In SSc patients, a statistically significant correlation was found between calprotectin and the modified Rodnan skin score (mRSS) (r = 0.402, p < 0.001), disease activity index (DAI) (r = 0.420, p < 0.001), disease severity scale (DSS) (r = 0.365, p < 0.01), forced vital capacity (FVC) (r = -0.459, p < 0.001), and diffusion lung capacity for carbon monoxide (DLco) (r = -0.445, p < 0.001). Calprotectin was higher in SSc patients with digital ulcers (DUs) than in SSc patients without DUs [2.98 mcg/mL (IQR 2.07;4.29) vs. 2.08 mcg/mL (IQR 1.71;2.45), p < 0.01] and in SSc patients with interstitial lung disease (ILD) compared to SSc patients without ILD [2.56 mcg/mL (IQR 1.94;3.03) vs. 1.96 mcg/mL (IQR 1.7;2.35), p < 0.01]. The multivariable stepwise logistic regression analysis showed calprotectin to be independently associated with DUs [OR 2.531 (CI 95%: 1.074;5.961), p < 0.05] and ILD [OR 3.687 (CI 95%: 1.336;10.170), p < 0.05] in SSc patients. Serum calprotectin is associated with DUs and ILD in SSc patients.