Human chitotriosidase: a potential new marker of sarcoidosis severity

Sarcoidosis is a multisystemic granulomatous disorder of unknown etiology. The unpredictable clinical course of the disease has prompted research into biomarkers useful for predicting outcome. Among the potential markers of sarcoidosis, a recently proposed indicator was chitotriosidase, a chitinase produced by activated macrophages. Chitotriosidase is involved in the defense against pathogens containing chitin. Increased concentrations of chitotriosidase have been observed in a number of lysosomal storage diseases including Gaucher disease and more recently also in sarcoidosis. In 2004, significantly higher serum chitotriosidase activity was reported for the first time in sarcoidosis patients with respect to controls (p < 0.01); a similar increase was subsequently observed in bronchoalveolar lavage of these patients. In 2007, an increase in enzyme activity was described in juvenile sarcoidosis. Chitotriosidase activity was found to be correlated with angiotensin-converting enzyme levels in serum, radiological stages and quantitative high-resonance CT score for sarcoidosis, suggesting that this enzyme could be a potential marker of disease severity worthy of further study. To evaluate the sensitivity and specificity of this marker, further analysis was done in other granulomatous and diffuse lung diseases. Here, we review the principal literature and the recent evidence of chitotriosidase as a possible marker of sarcoidosis.