Role of ACE2-Ang (1-7)-Mas receptor axis in heart failure with preserved ejection fraction with hypertension

Abstract

To investigate changes in the angiotensin converting enzyme 2 (ACE2) and angiotensin (1-7) [Ang (1-7)] and to explore the role of ACE2-Ang (1-7)-Mas receptor axis in hypertension with heart failure with preserved ejection fraction (HFPEF). Methods: A total of 70 patients with primary hypertension and preserved left ventricular ejection fraction (LVEF>50%) were recruited and patients were divided into a hypertension group (HBP) and a heart failure with preserved ejection fraction group (HFpEF) according to the diagnostic criteria of HFpEF. Thirty-five healthy participants were selected randomly as a control group. Enzyme linked immunosorbent assays (ELISA) method was used to detect concentration of Ang (1-7), ACE2, angiotensin II (Ang II), brain natriuretic peptide (BNP) in plasma. Male Sprague- Dawley (SD) rats was randomly divided into 2 groups: An HFpEF group (n=16) and a sham group (n=8). Rats (n=8) in the AAC group were given Ang (1-7) [0.5 mg/(kg.d), intraperitoneally] for 6 weeks, and the rest were given equal dose normal saline. Then all the rats were killed, and the hearts were taken out for hematoxylineosin (HE) staining. The protein expressions of angiotensin converting enzyme (ACE), ACE2, and Mas receptor were detected by Western blot. Results: The BNP and Ang II were significantly increased in the HBP group and the HFpEF group compared with the control group (P<0.01). There were not significantly different in levels of ACE2 and Ang (1-7) between the HBP group and control group (P>0.05), whereas those levels were significantly increased in the HFpEF group compared with the HBP group and control group (P<0.01). HE staining showed obvious hypertrophy of myocardial cell in the AAC group compared with the sham group. Hypertrophy of myocardial cell in the AAC+Ang (1-7) group was significantly higher than that in the AAC group. Expressions of ACE, ACE2, and Mas receptor proteins were significantly higher in the AAC group than those in the sham group (P<0.05), while the expressions of ACE2 and Mas receptor proteins in the AAC+Ang (1-7) group were significantly higher than those in the AAC group (P<0.05). There was no significant difference in the ACE protein expression between groups (P>0.05). Conclusion: ACE2 and Ang (1-7) are important predictive factors for the severity of heart failure and myocardial remodeling of HFpEF with hypertension; ACE2-Ang (1-7)-Mas receptor axis may play a protective role in preventing myocardial remodeling in HFpEF with hypertension.