Serum levels of chitotriosidase as a marker of disease activity and clinical stage in sarcoidosis

Background: Sarcoidosis is a systemic granulomatous disease characterized by T-lymphocyte activation and lymphocyte migration into involved organs, usually the lungs. The amounts of a number of biochemical markers, such as angiotensin converting enzyme (ACE) activity, increase in the serum of patients with sarcoidosis. Chitotriosidase is an enzyme secreted by activated macrophages able to catalyze the hydrolysis of both chitin and chitin-like substrates. Chitotriosidase is involved in defense against, and in degradation of chitin-containing pathogens such as fungi, nematodes, and insects. Methods: Forty-three patients affected by chronic sarcoidosis, in active (23 patients) or inactive (20 patients) phase, were studied. Serum levels of chitotriosidase and ACE activity were evaluated and compared with those of 32 healthy subjects. Serum chitotriosidase concentration and ACE activity were also correlated with radiographic stage of disease. Results: Individuals with chronic sarcoidosis have higher serum chitotriosidase concentrations and ACE activity than those of normal subjects. Sarcoidosis patients in the active phase of the disease had significantly higher chitotriosidase and ACE levels than those in the inactive phase. In contrast to serum ACE activity, a significant relationship between serum levels of chitotriosidase and the four radiographic stages of the disease was observed. Conclusion: Although the data need to be validated by further investigation, the observations made in this study seem to indicate that serum chitotriosidase concentrations may be a useful marker for monitoring sarcoidosis disease activity and prognosis.