Recombinant human angiotensin-converting enzyme 2 plays a protective role in mice with sepsis-induced cardiac dysfunction through multiple signaling pathways dependent on converting angiotensin II to angiotensin 1-7.

BACKGROUND

Sepsis-induced cardiac dysfunction (SICD) is a common complication of sepsis and contributes to mortality and the complexity of management in patients with sepsis. Recombinant human angiotensin-converting enzyme 2 (rhACE2) has been reported to protect the heart from injury and dysfunction in conditions which involve increased angiotensin II (Ang II). In this study, we aimed to detect the effects of rhACE2 on SICD.

METHODS

A SICD model was developed in male C57/B6 mice by lipopolysaccharide (LPS) intraperitoneal injection. When cardiac dysfunction was confirmed by echocardiography 3 hours after LPS administration, mice were treated with either saline, rhACE2, or rhACE2 + A779. All mice received echocardiographic examination at 6 hours after LPS injection and then were sacrificed for serum and myocardial tissues collection. Angiotensin, cardiac troponin I (cTnI), and inflammatory markers in serum were measured. Histopathology features were examined by hematoxylin and eosin (HE) and terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) staining to evaluate structure injury and cell pyroptosis rate in heart tissue respectively. Pyroptosis-related proteins and signaling pathways involved in nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation in heart tissue were investigated by western blot (WB).

RESULTS

RhACE2 relieved myocardial injury and improved cardiac function in mice with SICD accompanied by decrease of Ang II and increase of angiotensin 1-7 (Ang 1-7) in serum. RhACE2 diminished activation of NLRP3 inflammasome, inflammatory response, and cell pyroptosis induced by LPS. In addition, rhACE2 partly inhibited activation of nuclear factor κB (NF-κB), the p38 mitogen-activated protein kinase (MAPK) pathway, and promoted activation of the AMP-activated protein kinase-α1 (AMPK-α1) pathway in heart tissue. Administration of A779 offset the inhibitive effects of rhACE2 on NLRP3 expression and protective role on cardiac injury and dysfunction in mice with SICD.

CONCLUSIONS

RhACE2 plays a protective role in SICD, ameliorating cardiac injury and dysfunction through NF-κB, p38 MAPK, and the AMPK-α1/NLRP3 inflammasome pathway dependent on converting Ang II to Ang 1-7.