MPO and systemic lupus erythematosus: MPO is present on NETs in target organs in SLE, atherosclerosis, and renal vasculitis [14, 59, 60] and it is therefore plausible, although not yet experimentally confirmed, that NET-bound MPO contributes to organ inflammation and injury in those conditions given that NET-associated MPO is enzymatically active and can produce tissue damaging HOCl in the presence of H2O2 [39].