The main treatment of acute myocardial infarction and ischemic stroke is timely reperfusion of the occluded artery to restore blood flow. In the framework of this thesis, the biological effects of different clinically available intravenous beta-blockers have been tested in different acute conditions. Consequently, synapses in autonomic ganglia are mediated by the interaction of acetylcholine (ACh) with nicotinic receptors (NN) located on second-order neurons.
Therefore, stimulation of the sympathetic nervous system results in the release of epinephrine (80%) and norepinephrine (20%) into the bloodstream, eliciting a systemic nontargeted sympathetic response (28). ADRBs belong to the family of G protein-coupled receptors (GPCRs) in the seven trans-membrane domain superfamily. Differences between the location of the ganglia in the sympathetic and parasympathetic branches of the ANS.
It results in a reduction in the constitutive activity of the system by reducing the number of active receptors. Because of the anti-ischemic, anti-arrhythmic and anti-adrenergic properties (72), current overall guidelines recommend that beta-blockers should be continued during and after hospitalization for all patients with STEMI and no contraindications to their use (4, 73). . The mainstay of acute myocardial and cerebral infarction is rapid reperfusion of the occluded artery to restore blood flow mainly by PCI in the case of AMI (95), or pharmacological and/or endovascular therapy in the case of ischemic stroke (20, 96).
First, the evaluation of MVO in the patient cohort of the METOCARD-CNIC study showed a significantly lower incidence and magnitude in patients receiving i.v.
Metoprolol exerts a non-class effect against ischaemia-reperfusion injury
The effect of b-blockers on the conformation of the b1 adrenergic receptor was studied in silico. Modeling shows that metoprolol binding induces a unique conformational change in the b1 adrenergic receptor intracellular domain. The effect of the tested b-blockers on neutrophil migration was assessed in a chemokine-induced transwell migration assay (Figure 2A).
The interaction of the three b-blockers with the b1 adrenergic receptor (b1AR) was investigated by in silico approaches. Finally, we studied in silico structural changes that occur in the b1AR when bound to the different b-blockers. This non-class effect was confirmed in the other in vitro and in vivo models of exacerbated inflammation investigated.
Our previous results showed that the cardioprotective effect of metoprolol is mediated by the b1AR, with no involvement of the b2AR.9 We therefore focused the in silico analysis exclusively on the b1AR. Impact of the timing of metoprolol administration during STEMI on infarct size and ventricular function.
Neutrophil β1 adrenergic receptor blockade blunts stroke-associated
The only clinically available interventions are intravenous (i.v.) administration of the fibrinolytic agent recombinant tissue plasminogen activator (rt-PA) and, more recently, endovascular thrombectomy alone or in combination with rt-PA (Powers et al.,2019). Recently, tissue reperfusion has been shown to exacerbate the inflammatory response, resulting in massive leukocyte infiltration (Lin et al., 2016). We recently demonstrated that in the context of myocardial infarction, acute blockade of neutrophil β1-adrenoceptors (β1AR) by metoprolol - but not by other β-blockers - ameliorates myocardial I/R damage (Clemente-Moragon et al., 2020; Garcia-Prieto et al., 2017).
The immune-related procedures used adhere to the recommendations of the British Journal of Pharmacology (Alexander et al., 2018). The data and statistical analysis conform to the British Journal of Pharmacology recommendations for experimental design and analysis in pharmacology (Curtis et al., 2018). Upon reperfusion, MVO induced by circulating cells contributes significantly to the final extent of injury (Ibanez et al., 2015).
Neutrophil pro-inflammatory activation after stroke is associated with increased IS and BBB breakdown (Sstrecker et al., 2017). To this end, we used 2D intravital microscopy (IVM) to image migration in the cremaster muscle vessels of mice injected with TNFα, which triggers massive neutrophil recruitment (Figure 5d) (Sreeramkumar et al., 2014). To further investigate whether the benefits of metoprolol in stroke are mediated by an effect on neutrophils, as has been previously described for myocardial infarction (Garcia-Prieto et al., 2017), we evaluated the effect of β1AR blockade in the absence of circulating neutrophils (Figure 6a).
Although some studies have attributed neuroprotective properties to beta-blockers in stroke (Ajmo et al., 2009; Here, our findings provide strong evidence that the modulatory effect of metoprolol on neutrophil dynamics (Garcia-Prieto et al., 2017) significantly reduces brain injury and promotes inflammatory resolution and tissue repair in a validated MCAO/R model (Cai et al., 2016) (Graphical Abstract, in Supporting Information).This was important because there is uncertainty regarding the optimal timing for IS quantification (Neumann-Haefelin et al. , 2000).
Cerebral edema is a serious complication of stroke, and medical strategies to reduce its impact are limited (Thoren et al.,2017). The latter promotes neutrophil clearance by microglia and triggers anti-inflammatory and pro-resolving responses (Figure 4) (Doran et al.,2020; Jones et al.,2016). The ROS scavenger redaravone has been shown to improve functional outcomes in several clinical trials when administered within 24 hours of stroke onset (Enomoto et al., 2019).
Metoprolol in critically ill patients with COVID-19
The capacity of neutrophils to migrate towards the chemokine C-X-C motif ligand 1 (CXCL1) was assessed using a modification of the method of Villablanca et al. Clemente-Moragón, A., et al.: β1AR blockade blunts stroke neuroinflammation, which contributes to creating a pro-resolving microenvironment that favors long-term recovery. Clemente-Moragón, A., et al: β1AR blockade blunts stroke neuroinflammation Supplementary Fig. A) Area at risk (AAR), determined by dynamic susceptibility contrast perfusion imaging and infarct size assessed by coronal T2-weighted (T2W) MRI at 24 h after reperfusion (vehicle, n=19; . metoprolol, n=23).
Clemente-Moragón, A., et al.: β1AR blockade blunts stroke neuroinflammation Supplementary Fig. A) Infarct size (IS) normalized to tissue at risk of infarction assessed as perfusion-diffusion mismatch (PDM). Clemente-Moragón, A., et al: β1AR blockade blunts stroke neuroinflammation Supplementary Fig. A) Representative GFAP immunohistochemistry (IHC) on coronal sections 7 days after reperfusion showing a glial (red outline) in the core lesion of a vehicle-treated rat (left) and the absence of scarring in a metoprolol-treated rat (right). Clemente-Moragón, A., et al: β1AR blockade blunts stroke neuroinflammation proteoglycans (CSPGs) on coronal sections 7 days after reperfusion, showing CSPG deposition (red outline) in the core lesion of a vehicle-treated rat (left) and its absence in a metoprolol-treated rat (right).
Clemente-Moragón, A., et al: β1AR blockade attenuates stroke neuroinflammation (A) Representative IHC of NeuN, GFAP, and Iba1 in coronal sections at 24 hours after reperfusion, showing no difference in baseline lesion between vehicle (left) and metoprolol (right). Clemente-Moragón, A., et al: β1AR blockade attenuates stroke neuroinflammation Fig. A) Flow cytometry plots illustrating the purity of glia-based co-cultures. Clemente-Moragón, A., et al: β1AR blockade attenuates stroke neuroinflammation Fig. A) White blood cell count after anti-PMN serum treatment assessed by hemocytometry.
Clemente-Moragón, A., et al: β1AR blockade blunts neuroinflammation in stroke To assess whether metoprolol induces neuroprotection in the absence of circulating neutrophils, an additional group of 20 rats were depleted of peripheral neutrophils before MCAO/R blood.
