Autocrine Bradykinin Release Promotes Ischemic Preconditioning-Induced Cytoprotection in Bovine Aortic Endothelial Cells

Abstract

The aims of this study were to assess whether ischemic preconditioning (PC) induces bradykinin (Bk) synthesis in bovine aortic endothelial cells (bAECs) and, if so, to explore the molecular mechanisms by which this peptide provides cytoprotection against hypoxia. PC was induced by exposing bAECs to three cycles of 15 min of hypoxia followed by 15 min of reoxygenation. Bk synthesis peaked in correspondence to the early and late phases of PC (10−12 M and 10−11 M, respectively) and was abolished by a selective tissue kallikrein inhibitor, aprotinin. Stimulation with exogenous Bk at concentrations of 10−12 M and 10−11 M reduced the cell death induced by 12 h of hypoxia by 50%. Pretreatment with HOE−140, a Bk receptor 2 (BKR2) inhibitor, in bAECs exposed to 12 h of hypoxia, abrogated the cytoprotective effect of early and late PC, whereas des-Arg-HOE-140, a Bk receptor 1 (BKR1) inhibitor, affected only the late PC. In addition, we found that PC evoked endocytosis and the recycling of BKR2 during both the early and late phases, and that inhibition of these pathways affected PC-mediated cytoprotection. Finally, we evaluated the activation of PKA and Akt in the presence or absence of BKR2 inhibitor. HOE-140 abrogated PKA and Akt activation during both early and late PC. Consistently, BKR2 inhibition abolished cross-talk between PKA and Akt in PC. In bAECs, Bk-synthesis evoked by PC mediates the protection against both apoptotic and necrotic hypoxia-induced cell death in an autocrine manner, by both BKR2- and BKR1-dependent mechanisms.

The Rationale for Angiotensin Receptor Neprilysin Inhibitors in a Multi-Targeted Therapeutic Approach to COVID-19

“…In fact, atrial NP (ANP) attenuates acute inflammatory effects of mast cells or histamine [ 49 ] and C-type NP (CNP) regulates and preserves cardiac structure, function, and coronary reactivity via activation of NP receptor-C (NPR-C) [ 50 ]. BK activates reperfusion injury salvage kinase (RISK) pathways in cardiomyocytes [ 51 ] and significantly reduces apoptotic death induced by prolonged hypoxia in arterial endothelial cells [ 52 ]. SP induces bone marrow stem cell mobilization that is able to suppress inflammation in ischemic heart [ 53 ].…”

The Rationale of Neprilysin Inhibition in Prevention of Myocardial Ischemia-Reperfusion Injury during ST-Elevation Myocardial Infarction

“…Released Bk, through an autocrine mechanism, promotes cytoprotection against prolonged hypoxia [129]. This phenomenon is mainly mediated by the internalization of BKR2, which, in turn, promotes the cross-talk between protein kinase A (PKA) and Akt [129], independently by NO synthesis (Figure 2) [130]. Because these results showed that locally synthesized Bk is implied in arterial endothelium survival, they account for a systemic protective role of Bk against IRI.…”

“…Firstly, concomitant NEP and AT1Rs antagonism increase levels of molecular compounds leading to activation of different pro-survival pathways, such as PI3K-Akt, PKC, PKG, AMPK, and ERK ( Figure 1). In particular, augmented Bk levels mediate protection against MIRI at myocardial [125][126][127] end endothelial level [129], whereas AT1Rs blocking inhibits pro-apoptotic pathways mediated by acute Ang II increase. Consistently, the reflex increased Ang II levels may activate cRAS and iRAS that enhance cell protection against oxidative stress [115].…”

“…However, Bk does not only protect the heart against MIRI, but also prevents apoptotic death induced by prolonged hypoxia in arterial endothelial cells. In particular, PC induces Bk synthesis by increasing KLK1 activity in endothelial cells [129]. Released Bk, through an autocrine mechanism, promotes cytoprotection against prolonged hypoxia [129].…”

“…In particular, PC induces Bk synthesis by increasing KLK1 activity in endothelial cells [129]. Released Bk, through an autocrine mechanism, promotes cytoprotection against prolonged hypoxia [129]. This phenomenon is mainly mediated by the internalization of BKR2, which, in turn, promotes the cross-talk between protein kinase A (PKA) and Akt [129], independently by NO synthesis (Figure 2) [130].…”