Method: Thirty-six TA patients (≥3 ACR criteria, 1990) followed at Vasculitis unitis of a University hospital and 36 age-and-sex matched controls participated in the study. The serum level of IL-2, IL-6, IL-8, IL-12 and TNF-alfa were measured by LUMINEX (HSCYTO-60SK-05 Milliplex, Millipore, USA). IL-18 (Med & Biol Lab CO, Japan), MMP-3 and MMP-9 (R&D System, EUA) were measured by ELISA assay. Maximum standard uptake value (SUVmax) in arterial walls was registered by PET-CT (Gemini, Phylips, EUA). The TA activity was evaluated using NIH criteria
Result: The mean age of patients and controls was respectively 36.2 and 37.0 years and 92% of them were female. The serum level of IL-6 [13.3 pg/ml (95% CI 7.0-19.6) vs 3.4 pg/ml (95%CI 1.9-4.8) P<0.001] and of MMP-3 [647.8 pg/ml (95%CI 494.7-800.8) vs 563.7pg/ml (95%CI 439.4-688.0); P<0.001] were higher in TA patients than in controls. Comparing the serum level of these interleukins and metalloproteinases between patients classified as active vs inactive disease, only IL-6 was significantly higher in patients with active disease (22.5 pg/ml vs 7.5 pg/ml; P=0.027). Regarding SUVmax on PET-CT, patients with active disease had higher SUVmax values than those with inactive disease (P=0.042). ROC curve analysis showed that the value of SUVmax as a predictor of clinical activity (P=0.043; AUC=0.703; IC 95%=0.534–0.832). SUVmax ≥ 1.3 was associated with clinical activity (P=0.039). TNF-alfa levels were higher in patients with SUVmax ≥ 1.3, when compared to those <1.3 (P=0.045) and to controls (P=0.012). IL-6 and MMP3 levels were higher in patients with SUVmax ≥ 1.3 than in controls (P<0.001 and P=0.006, respectively). There was no significant difference regarding others serum biomarkers comparing TA patients and controls.
Conclusion: This is the first study evaluating various interleukins and metalloproteinase to assess disease activity in TA patients. The serum level of IL-6 was associated with disease activity. This study also finds a correlation between 18F-FDG uptake in PET-CT and disease activity. Therefore PET-CT and serum level of IL-6 appear to be promising tools to assess Takayasu arteritis disease activity.
Disclosure: A. E. D. Arraes, None; A. W. S. Souza, None; E. N. P. Lima, None; E. I. Sato, None.