Aims/hypothesis  

The interplay of ACE and type 2 ACE (ACE2) has been recognised as playing an important role in the tissue renin–angiotensin system within the kidney. In the present study, we measured urinary mRNA expression of ACE and ACE2 in patients with type 2 diabetic nephropathy.

Methods  

We studied 50 patients with diabetic nephropathy: 26 were being treated by ACE inhibitor (ACEI) alone (ACEI group), the other 24 by ACEI and angiotensin-receptor blocker (ARB) (ACEI+ARB group). mRNA expression of ACE and ACE2 was measured by real-time quantitative RT-PCR at 0 and 12 weeks. All patients were then followed for 56 weeks.

Results  

Proteinuria correlated significantly with urinary ACE (r = 0.454, p = 0.001) and ACE2 expression (r = 0.651, p < 0.001). Urinary ACE2 expression correlated with estimated GFR (r = −0.289, p = 0.042). In the ACEI group, there was a significant inverse correlation between the rate of GFR decline and urinary ACE2 expression at baseline (r = −0.423, p = 0.031) as well as at 12 weeks (r = −0.395, p = 0.046). In contrast, there was no significant correlation between the rate of GFR decline and urinary ACE2 expression at baseline or at 12 weeks in the ACEI+ARB group. The rate of GFR decline did not correlate with the baseline urinary ACE expression of either group.

Conclusion/interpretation  

There was a relationship between urinary mRNA expression of ACE2 and the degree of proteinuria. The physiological implication and possibility of clinical application of quantifying urinary ACE2 expression require further study.