Serum cytokine profiles in Takayasu's arteritis: search for biomarkers.

OBJECTIVES: Assessment of disease activity is one of the major difficulties in patients with Takayasu arteritis (TAK) during follow-up. To date, no biomarker is universally accepted to be a surrogate for active disease in TAK. In this study, we aimed to investigate levels of various pro-and anti-inflammatory molecules including serum granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-6, IL-8, IL-10, IL-18 and IL-23 in patients with TAK. METHODS: The study included 51 patients (age: 40.6±12.2 years, F/M: 45/6) with TAK and 42 age- and sex-matched healthy controls (age: 38.1±7.4 years, F/M: 38/4). All patients fulfilled the criteria of the American College of Rheumatology (ACR). TAK patients were evaluated by physician's global assessment (PGA; active/inactive) and ITAS2010 (Indian Takayasu Arteritis Clinical Activity Score) in terms of clinical activity in baseline and follow-up visits. Commercial enzyme linked immuno-sorbent assay (ELISA) kits were used for measurements of serum cytokine levels. RESULTS: At baseline, 21 (41.2%) patients were active according to PGA and 8 (15.7%) according to ITAS2010. Serum IL-6, IL-8 and IL-18 levels were significantly higher in patients with TAK, whereas GM-CSF, IL-10, IL-23 levels were similar to healthy controls. IL-8 significantly decreased in the follow-up, associated with a decrease of clinical activity, whereas IL-23 level significantly increased. When assessed by ITAS2010 active patients had significantly higher IL-18 levels. CONCLUSIONS: We found significantly increased IL-6, IL-8 and IL-18 levels in patients with TAK compared to healthy controls. Only IL-18 level was significantly higher in active patients assessed by ITAS2010. IL-18 was also the only cytokine in our study that correlated with CRP. These findings suggest that cytokines associated with neutrophilic, pro-inflammatory responses such as IL-6, IL-8 and IL-18 can be potential biomarkers for the assessment of disease activity in TAK and warrant further studies in larger series.