The IL-33/sST2 Axis in Thromboangiitis Obliterans

BACKGROUND: Until recently, it remains unknown whether thromboangiitis obliterans (TAO) is a type of systemic vasculitis. A high level of IL-33 and its soluble decoy receptor sST2 in the acute phase of systemic vasculitis has been demonstrated. METHODS: The serum level of IL-33 and sST2 in 50 TAO patients, 20 age- and smoking habit-matched controls and 19 age-matched non-smoker controls was evaluated. RESULTS: The mean level of IL-33 in TAO, smokers and non-smokers was 370.2±61.7ng/mL,132.14±2.6ng/mL and 11.3±0.38ng/mL, respectively. The IL-33 was significantly higher in the TAO than in either control groups (p < 0.001). The IL-33 in the acute phase of TAO was significantly higher than in the patients in the quiescent phase of the disease (p = 0.019). Also, IL-33 in the patients with gangrene was significantly higher than in the patients with non-healing ulcers (p = 0.021). The sST2 in the TAO patients was 49.3±5.58ng/mL, and in smoker and non-smoker controls, it was 45.3±6.3ng/mL and 4.11±0.17ng/mL, respectively. No significant difference was found between the patients and smoker control groups (p = 0.87). The mean ratio of IL-33/sST2 was 27.89±10.44 in the TAO group and, in smokers and non-smokers, it was 2.85±0.48 and 2.84±0.14, respectively. A significantly high level of IL-33/sST2 ratio was observed in TAO patients in both the active and quiescent phases of the disease in comparison to both control groups (p<0.001). CONCLUSION: The regulation pattern of IL-33/sST2 was different in TAO in comparison to autoimmune vasculitis.