Urinary ACE2 is associated with urinary L-FABP and albuminuria in patients with chronic kidney disease

Aim. Angiotensin-converting enzyme 2 (ACE2) is expressed in the kidney and may be a renoprotective enzyme since it converts angiotensin (Ang) II to Ang-(1-7). In addition, ACE2 has been detected in urine from patients with chronic kidney disease (CKD). The aim of this study was to determine the urinary ACE2 levels in patients with various stages of CKD and to identify the factors associated with the presence of ACE2. Methods. We assessed 152 patients with CKD stage G1-G4. The patients were classified according to the presence or absence of diabetes mellitus (DM) (DM group, n = 72; non-DM group, n = 80) and according to the estimated glomerular filtration rate (CKD stage G1/2 group, n = 40; CKD stage G3 group, n = 74; and CKD stage G4 group, n = 38). Parameters were urinary ACE2, urinary albumin/creatinine ratio (UACR), urinary liver-type fatty acid binding protein (L-FABP), estimated glomerular filtration rate, and other factors determined to be associated with elevated urinary ACE2. Results. Urinary ACE2 was significantly higher in patients with diabetes (p = 0.01) and in patients with CKD stage G4 compared with stages G1-G3 (p < 0.0001). Multivariable regression analysis revealed that urinary L-FABP and UACR were significantly associated with urinary ACE2 levels, indicating that urinary ACE2 is increased in patients with diabetes and advanced stage CKD. Conclusion. ACE2 might continuously protect from both glomerular and tubulointerstitial injury during CKD progression. Taken together, urinary ACE2 might be a marker of kidney renin-angiotensin system activation in such patients.