Biomarkers in sarcoidois follow-up: Angiotensin-converting enzyme or chitotriosidase?

Introduction: Chitotriosidase (CTO) and angiotensin-converting enzyme (ACE) are both markers of sarcoidosis activity and both derive from chronically activated macrophages. In this study we compared the two biomarkers in the follow-up of sarcoidosis. Methods: The study comprised 100 patients. Five were excluded because they lacked CTO activity (homozygotes for common CHIT1 polymorphism) and 8 because they were receiving ACE inhibitors (87 included, 46 female, mean age 44±13 years). The patients were followed-up for 24-60 months. CTO and ACE measurements were done every 3-6 months and correlated to clinical symptoms, chest X-ray and lung function (FVC, DLco). In 33 patients clinical outcome status (COS) at 5 years was determined. Results: Initially, ACE was increased above upper normal level in 35.6% and CTO in 98.9% of patients. ACE and CTO were both significantly lower in no disease groups (COS 1 and 2) versus persistent disease groups (COS 5 through 9) (p = 0.008 and p = 0.050, respectively). In the follow-up period, there was a positive correlation between ACE and CTO and changes in clinical symptoms (p Conclusions: Both biomarkers correlated similarly with COS score and with changes in clinical symptoms and chest X-ray. Only CTO correlated with changes in lung function. The interpretation of ACE values can be difficult due to large number of patients with ACE activity in the normal range. In comparison, CTO was increased in majority of patients and had a greater range of blood concentrations.