Traditionally viewed as important in the regulation of blood pressure, the renin-angiotensin system -and specifi cally the angiotensin-converting enzyme (ACE)angiotensin (Ang) II-AT 1 receptor axis -may play a prominent role to promote infl ammation and fi brosis. ACE2, a new component of the renin-angiotensin system, has emerged as a key enzyme that selectively degrades Ang II and generates Ang-(1-7), a bioactive peptide with anti-infl ammatory and anti-fi brotic actions. Takahashi and colleagues demonstrate circulating titers of inhibitory autoantibodies against ACE2 in patients with systemic sclerosis. The current study reveals a potentially novel mechanism to attenuate the catalytic activity of ACE2, thereby promoting the actions of Ang II. were chronically treated with inhibitors of the reninangiotensin system including aldosterone antagonists which may increase basal ACE2 expression potentially contributing to the protective mechanisms of these therapies.