Gonadectomy prevents the increase in blood pressure and glomerular injury in angiotensin-converting enzyme 2 knockout diabetic male mice. Effects on renin-angiotensin system

Background: Angiotensin-converting enzyme 2 (ACE2) deletion worsens kidney injury, and its amplification ameliorates diabetic nephropathy. Male sex increases the incidence, prevalence, and progression of chronic kidney disease in our environment. Method: Here, we studied the effect of ACE2 deficiency and gonadectomy (GDX) on diabetic nephropathy and its relationship with fibrosis, protein kinase B (Akt) activation, and the expression of several components of the renin-angiotensin system (RAS). Mice were injected with streptozotocin to induce diabetes and followed for 19 weeks. Physiological and renal parameters were studied in wild-type and ACE2 knockout (ACE2KO) male mice with and without GDX. Results: Diabetic ACE2KO showed increased blood pressure (BP), glomerular injury, and renal fibrosis compared with diabetic wild-type. Gonadectomized diabetic ACE2KO presented a decrease in BP. In the absence of ACE2, GDX attenuated albuminuria and renal lesions, such as mesangial matrix expansion and podocyte loss. Both, α-smooth muscle actin accumulation and collagen deposition were significantly decreased in renal cortex of gonadectomized diabetic ACE2KO but not diabetic wild-type mice. GDX also reduced circulating ACE activity in ACE2KO mice. Loss of ACE2 modified the effect of GDX on cortical gene expression of RAS in diabetic mice. Akt phosphorylation in renal cortex was increased by diabetes and loss of ACE2 and decreased by GDX in control and diabetic ACE2KO but not in wild-type mice. Conclusions: Our results suggest that GDX may exert a protective effect within the kidney under pathological conditions of diabetes and ACE2 deficiency. This renoprotection may be ascribed to different mechanisms such as decrease in BP, modulation of RAS, and downregulation of Akt-related pathways.