Tang X, Geng L, Feng X, et al. - Researchers aimed at determining the serum concentration and activity of angiotensin-converting enzyme 2 (ACE2) in patients with connective tissue diseases (CTDs). They included in total, 66 SLE, 55 systemic sclerosis (SSc), 31 Sjögren’s syndrome (SS) and 31 RA patients were involved. Patients with either of the four CTDs had significantly decreased ACE2 concentration compared with healthy individuals. They observed no link of the concentration with any special clinical feature except that it was slightly lower in patients with lupus nephritis than those without. SLE patients exhibited increase in ACE2 concentration with the increase of glucocorticoids, and no link with other treatments was identified. Overall findings suggest differences in the clinical significance of ACE2 concentration and activity among CTD patients. Preliminary data suggest that most of the treatments do not affect ACE2 levels.