[Serum Clara cell 16-kDa protein (CC16) levels and lung impairment in systemic sclerosis patients]

To assess clinical utility of serum Clara cell 16-kDa protein (CC16) measurements in relation with staging system for systemic sclerosis associated interstitial lung disease (SSc-ILD).

Serum levels of CC16 were determined by ELISA in 28 SSc patients and 30 healthy controls, and correlated with staging system for SSc-ILD in SSc patients. Lung involvement was assessed functionally (body plethysmography, diffusing capacity of the lung for carbon monoxide) and radiologically (an average disease extent on high resolution computed tomography of the lungs, HRCT) in SSc patients.

We observed statistically significant differences in serum CC16 levels between SSc patients and healthy controls only in non-smokers. However, serum CC16 concentrations were significantly elevated in patients with HRCT extent>20% in comparison to patients with HRCT extent<20% (p=0.01). They correlated positively with average disease extent on HRCT (p=0.04), an extent of a reticular pattern on HRCT (p<0.01), and negatively with a total lung capacity (TLC) (p=0.03) and the results of the 6-min walk test (p<0.01).

CC16 levels can be considered as a supplemental serum biomarker for SSc-ILD.