CTSG and systemic lupus erythematosus: For example, high levels and increased activity of cathepsin G have been linked to the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus (SLE) [36]; uncontrolled NET activity has been implicated in acute respiratory distress syndrome (ARDS) [43]; while elevated plasma levels of MPO are frequently detected in patients with sepsis [37].