Background: The renin-angiotensin system (RAS) is a proteolytic cascade which consists of multiple enzymes and effector peptides. Angiotensin-Converting Enzyme (ACE) is one of the major enzymes in the RAS and catalyzing the decapeptide Angiotensin I to the octapeptide Angiotensin II. There are other non-RAS effects of ACE like mediating and/or modulating inflammation. We aimed to explore the ACE activity in white and black South African men and establish the associations with a marker of inflammation.

Methods: In a bi-ethnic sample (n=30) consisting of white and African men, the RAS-Fingerprinting was determined with LC-MS/MS quantification of Angiotensin peptides. Blood pressure and other variables were determined with known methods. Soluble urokinase Plasminogen Activator Receptor (suPAR) levels were determined using the suPARnostic® ELISA kit.

Results: From the RAS-Fingerprinting and ACE activity (product-substrate ratio) it is evident that ACE activity is significantly lower in the normotensive African men compared to white men. The higher ACE activity found in the white men associated positively with reactive oxygen species (ROS) (r=0.59; p=0.02) and with suPAR (r=0.63; p=0.01) but not in the African men.

Conclusions: The ACE activity is higher in the white men and it seems that ACE may drive inflammation only in the white participants.