PON1 and systemic lupus erythematosus: Previous studies showed that HDL from SLE patients had decreased levels of apoA-I, decreased activity of antioxidant enzyme paraoxonase-1 (PON1) and increased levels of proinflammatory protein serum amyloid A1 (SAA1) and pro-oxidant enzyme myeloperoxidase (MPO) [6, 7].