mln-4760 and diminazene-aceturate

To investigate the role of angiotensin-converting enzyme 2 (ACE2) in hyperoxic lung injury.. Adult mice were exposed to 95% O2 for 72 h to induce hyperoxic lung injury, and simultaneously treated with ACE2 agonist diminazene aceturate (DIZE) or inhibitor MLN-4760. ACE2 expression/activity in lung tissue and angiotensin (Ang)-(1-7)/Ang II in bronchoalveolar lavage fluid (BALF), and the severity of hyperoxic lung injury were evaluated. The levels of inflammatory factors in BALF and lung tissue and the expression levels of phospho-p65, p65 and IkBα were measured. Oxidative parameter and antioxidant enzyme levels in lung tissue were measured to assess oxidative stress. Finally, the expression levels of nuclear factor-erythroid-2-related factor (Nrf2), NAD(P)H quinine oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) were measured using Western blotting.. Hyperoxia treatment significantly decreased lung ACE2 expression/activity and increased the Ang II/Ang-(1-7) ratio, while co-treatment with hyperoxia and DIZE significantly increased lung ACE2 expression/activity and decreased the Ang II/Ang-(1-7) ratio. By contrast, co-treatment with hyperoxia and MLN-4760 significantly decreased lung ACE2 expression/activity and increased the Ang II/Ang-(1-7) ratio. Hyperoxia treatment induced significant lung injury, inflammatory response and oxidative stress, which were attenuated by DIZE but aggravated by MLN-4760. The NF-κB pathways were activated by hyperoxia and MLN-4760 but inhibited by DIZE. The Nrf2 pathway and its downstream proteins NQO1 and HO-1 were activated by DIZE but inhibited by MLN-4760.. Activation of ACE2 can reduce the severity of hyperoxic lung injury by inhibiting inflammatory response and oxidative stress. ACE2 can inhibit the NF-κB pathway and activate the Nrf2/HO-1/NQO1 pathway, which may be involved in the underlying mechanism.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Animals; Bronchoalveolar Lavage Fluid; Diminazene; Hyperoxia; Imidazoles; Leucine; Lung Injury; Male; Mice; Mice, Inbred BALB C; NF-E2-Related Factor 2; NF-kappa B; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A

The angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis represents a promising target for inducing stroke neuroprotection. Here, we explored stroke-induced changes in expression and activity of endogenous angiotensin-converting enzyme 2 and other system components in Sprague-Dawley rats. To evaluate the clinical feasibility of treatments that target this axis and that may act in synergy with stroke-induced changes, we also tested the neuroprotective effects of diminazene aceturate, an angiotensin-converting enzyme 2 activator, administered systemically post stroke. Among rats that underwent experimental endothelin-1-induced ischemic stroke, angiotensin-converting enzyme 2 activity in the cerebral cortex and striatum increased in the 24 hours after stroke. Serum angiotensin-converting enzyme 2 activity was decreased within 4 hours post stroke, but rebounded to reach higher than baseline levels 3 days post stroke. Treatment after stroke with systemically applied diminazene resulted in decreased infarct volume and improved neurological function without apparent increases in cerebral blood flow. Central infusion of A-779, a Mas receptor antagonist, resulted in larger infarct volumes in diminazene-treated rats, and central infusion of the angiotensin-converting enzyme 2 inhibitor MLN-4760 alone worsened neurological function. The dynamic alterations of the protective angiotensin-converting enzyme 2 pathway after stroke suggest that it may be a favorable therapeutic target. Indeed, significant neuroprotection resulted from poststroke angiotensin-converting enzyme 2 activation, likely via Mas signaling in a blood flow-independent manner. Our findings suggest that stroke therapeutics that target the angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis may interact cooperatively with endogenous stroke-induced changes, lending promise to their further study as neuroprotective agents.

Topics: ADAM Proteins; ADAM17 Protein; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Cerebral Cortex; Cerebral Infarction; Cerebrovascular Circulation; Corpus Striatum; Diminazene; Disease Models, Animal; Endothelin-1; Enzyme Activation; Imidazoles; Infarction, Middle Cerebral Artery; Infusions, Intraventricular; Leucine; Male; Neuroprotective Agents; Peptide Fragments; Peptidyl-Dipeptidase A; Proto-Oncogene Mas; Proto-Oncogene Proteins; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Renin-Angiotensin System; RNA, Messenger