mln-4760 and Acute-Lung-Injury

Previous studies have reported that lipoxin A4 (LXA4) and the angiotensin I-converting enzyme 2 (ACE2), angiotensin-(1-7) [Ang-(1-7)], and its receptor Mas [ACE2-Ang-(1-7)-Mas] axis play important protective roles in acute lung injury (ALI). However, there is still no direct evidence of LXA4-mediated protection via the ACE2-Ang-(1-7)-Mas axis during ALI. This work was performed using an LPS-induced ALI mouse model and the data indicated the following. First, the animal model was established successfully and LXA4 ameliorated LPS-induced ALI. Second, LXA4 could increase the concentration and activity of ACE2 and the levels of Ang-(1-7) and Mas markedly. Third, LXA4 decreased the levels of TNF-α, IL-1β, and reactive oxygen species while increasing IL-10 levels. Fourth, LXA4 inhibited the activation of the NF-κB signal pathway and repressed the degradation of inhibitor of NF-κB, the phosphorylation of NF-κB, and the translocation of NF-κB. Finally, and more importantly, BOC-2 (LXA4 receptor inhibitor), MLN-4760 (ACE2 inhibitor), and A779 (Mas receptor antagonist) were found to reverse all of the effects of LXA4. Our data provide evidence that LXA4 protects the lung from ALI through regulation of the ACE2-Ang-(1-7)-Mas axis.

Topics: Acute Lung Injury; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Cell Line, Tumor; Disease Models, Animal; Humans; Imidazoles; Leucine; Lipopolysaccharides; Lipoxins; Male; Mice; NF-kappa B; Peptide Fragments; Peptidyl-Dipeptidase A; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptors, G-Protein-Coupled; Signal Transduction

Acute respiratory distress syndrome (ARDS) caused by severe sepsis remains a major challenge in intensive care medicine. ACE2 has been shown to protect against lung injury. However, the mechanisms of its protective effects on ARDS are largely unknown. Here, we report that ACE2 prevents LPS-induced ARDS by inhibiting MAPKs and NF-κB signaling pathway. Lentiviral packaged Ace2 cDNA or Ace2 shRNA was intratracheally administrated into the lungs of male SD rats. Two weeks after gene transfer, animals received LPS (7.5 mg/Kg) injection alone or in combination with Mas receptor antagonist A779 (10 μg/Kg) or ACE2 inhibitor MLN-4760 (1 mg/Kg) pretreatment. LPS-induced lung injury and inflammatory response were significantly prevented by ACE2 overexpression and deteriorated by Ace2 shRNA. A779 or MLN-4760 pretreatment abolished the protective effects of ACE2. Moreover, overexpression of ACE2 significantly reduced the Ang II/Ang-(1-7) ratio in BALF and up-regulated Mas mRNA expression in lung, which was reversed by A779. Importantly, the blockade of ACE2 on LPS-induced phosphorylation of ERK1/2, p38 and p50/p65 was also abolished by A779. Whereas, only the ERK1/2 inhibitor significantly attenuated lung injury in ACE2 overexpressing rats pretreated with A779. Our observation suggests that AEC2 attenuates LPS-induced ARDS via the Ang-(1-7)/Mas pathway by inhibiting ERK/NF-κB activation.

Topics: Acute Lung Injury; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Gene Expression Regulation, Enzymologic; Gene Knockdown Techniques; Imidazoles; Lentivirus; Leucine; Lipopolysaccharides; Lung; Male; MAP Kinase Signaling System; NF-kappa B; Peptidyl-Dipeptidase A; Proto-Oncogene Mas; Proto-Oncogene Proteins; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Signal Transduction