Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Paper Nephron Clin Pract 2012;121:c144–c150 DOI: 10.1159/000345508 Circulating Angiotensin-Converting Enzyme 2 Activity in Kidney Transplantation: A Longitudinal Pilot Study María José Soler Marta Riera Marta Crespo Marisa Mir Eva Márquez María José Pascual Josep M. Puig Julio Pascual Department of Nephrology, Hospital del Mar-IMIM, Barcelona, Spain -glutamyl transferase ( -GT) (r = 0.52), age (r = 0.24), and glycosylated hemoglobin (r = 0.19) (p ! 0.05). By multiple regression analysis, age, serum creatinine, and serum -GT were independent predictors of serum ACE2 activity (r = 0.66, p ! 0.001). Conclusions: Circulating ACE2 activity is measurable in KT patients and directly correlates with age, renal allograft and liver function parameters. These findings suggest that measurement of serum ACE2 may be used as a non-invasive marker to understand the role of the renin-an- giotensin system in KT patients. Copyright © 2012 S. Karger AG, Basel Introduction Patients with chronic kidney disease and patients with end-stage kidney disease, either treated with dialysis or receiving a kidney transplant (KT), have an increased cardiovascular risk that accounts for more than 50% of the overall mortality [1, 2]. Coronary artery disease is one of the most important causes of morbidity and mortality in patients with renal disease [3]. The risk of cardiovas- Key Words Angiotensin-converting enzyme 2  Graft function  Kidney transplant  Renin angiotensin system Abstract Background/Aims: Angiotensin-converting enzyme 2 (ACE2) is the only known active homologue of ACE, and degrades angiotensin (Ang) II and Ang I to Ang(1–7) and Ang(1–9), re- spectively. The role of ACE2 in kidney transplant (KT) is un- known. Our objective was to investigate circulating ACE2 ac- tivity in KT patients, and the relationship between serum ACE2 activity and age, gender, graft function and cardiovas- cular risk markers in KT patients. Methods: 113 KT patients with stable graft function were included in this cross-sec- tional study. Circulating ACE2 activity was assessed using a fluorescent assay. Results: Circulating ACE2 activity was de- tectable in KT patients and was increased in KT with ischemic heart disease as compared to KT without ischemic heart dis- ease (105.9 8 8.7 vs. 97.1 8 7.05 relative fluorescence units (RFU)/ l/h, p ! 0.05). ACE2 activity was increased in male KT as compared to females (105.2 8 9.1 vs. 84.7 8 6.9 RFU/ l/h, p = 0.05). ACE2 activity correlated positively with serum cre- atinine (r = 0.27), serum urea (r = 0.29), age (r = 0.24), aspar- tate transaminase (r = 0.39), alanine transaminase (r = 0.48), Received: July 10, 2012 Accepted: October 26, 2012 Published online: December 19, 2012 María José Soler Romeo Department of Nephrology, Hospital del Mar Passeig Marítim 25–29 ES–08003 Barcelona (Spain) E-Mail msoler  @  parcdesalutmar.cat © 2012 S. Karger AG, Basel 1660–2110/12/1214–0144$38.00/0 Accessible online at: www.karger.com/nec M.J. Soler and M. Riera contributed equally to this work.