Club cell protein 16 as a biomarker for early detection of silicosis

Background & objectives: Clinically silicosis is diagnosed by chest X-ray showing specific opacities along with history of silica dust exposure. Diagnosis is invariably made at an advanced or end stage when it is irreversible. Moreover, silicosis patients are susceptible to develop tuberculosis. Therefore, a suitable biomarker for early detection of silicosis is needed. This study evaluated the suitability of club cell protein (CC16) as a biomarker for early detection of silicosis.

Methods: This pilot study included 121 individuals from X-ray-confirmed/advanced silicosis, moderate silica dust-exposed workers and healthy controls from western India. CC16 levels were quantified in serum samples through ELISA. Sensitivity and specificity of CC16 values at different cut-off points were calculated in both non-smokers and smokers.

Results: Serum CC16 level was significantly (P <0.01) decreased in X-ray confirmed advanced silicosis patients (4.7±3.07 ng/ml) followed by moderately exposed workers (10.2±1.77 ng/ml) as compared to healthy non-exposed individuals (16.7±3.81 ng/ml). Tobacco smoking also caused a significant decrease of serum CC16 concentration in both healthy (10.2±1.12 ng/ml) and advanced silicosis workers (2.6±2.28 ng/ml) compared to non-smokers. Sensitivity and specificity of CC16 values were also found to be ≥83 per cent for screening all categories of individuals.

Interpretation & conclusions: Because of high sensitivity and specificity, serum CC16 could be used as predictive biomarker for suspicion and early detection of silicosis, which would help in reducing/delaying premature deaths caused by silicosis. It would also control silicotuberculosis additionally.

Keywords: Club cell protein; dust exposure; early detection biomarker; serum; silicosis.