ADAMTS-13 metalloprotease abnormalities in systemic lupus erythematosus: is there a correlation with disease status?

To clarify the role of ADAMTS-13 in the pathogenesis of thrombotic microangiopathy in systemic lupus erythematosus (SLE) we evaluated ADAMTS-13 profile (metalloprotease antigen levels, anti-ADAMTS-13 autoantibody levels, activity) in distinct patient groups according to disease activity, extent of cumulative tissue damage and history of antiphospholipid syndrome or end-organ damage. Forty-one lupus patients were analysed. ADAMTS-13 metalloprotease antigen levels and anti-ADAMTS-13 autoantibodies were evaluated by ELISA. ADAMTS-13 activity was measured by Fluorescence resonance energy transfer (FRET) technique. ADAMTS-13 metalloprotease antigen levels were significantly decreased in patients with Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) >1 (p<0.05). ADAMTS-13 metalloprotease antigen levels also exhibited a significant inverse correlation with anti-dsDNA levels (r= -0.60, p<0.05). Anti-ADAMTS-13 autoantibodies were marginally higher in patients with positive anti-dsDNA (p=0.08). Additionally, patients with positive anti-ADAMTS-13 autoantibodies exhibited the lowest activity levels (p<0.05). To our knowledge ADAMTS-13 profile in SLE has not been studied in regard to composite structured indices. The results of this study suggest that in patients with active SLE or considerable cumulative tissue damage, ADAMTS-13 levels may be decreased and anti-ADAMTS-13 autoantibodies may partially mediate this reduction. Further evaluation of ADAMTS-13 profile may explain its role in the pathogenesis of thrombotic microangiopathy in lupus patients and reveal a potential prognostic marker of microthrombotic manifestations in SLE.