Role of kinase inhibition of G 2 protein-coupled receptors (GRK2) in the treatment of Sepsis

Abstract

Sepsis is a lethal disease characterized by an intense and deregulated sistemic immune response (POLAT et al., 2017). Multiple organ failure and lethality at sepsis are characterized by the increase of inflammatory mediators and impaired innate immune response (DELANO; WARD, 2016). In this context, there is the occurrence of cardiovascular dysfunction. At sepsis, it occurs systemic vasodilatation and hypovolemia resulting in venous return decrease, which leads to a hypotension state and leads to a distributive shock sepsis induced (GYAWALI; RAMAKRISHNA; DHAMOON, 2019). In pathogen invasion episodes, occurs leukocyte recruitment, which one of them are the neutrophils (MAYADAS; CULLERE; LOWELL, 2014). Neutrophil migration to infection site plays a key role at pathogen removal and early inflammation control. During an inflammatory process, neutrophil migration from blood to tissue is dependent of chemotactic molecules. These molecules bind to specific receptors at neutrophil plasma membrane (LERMAN; KIM, 2015). For example, at septic conditions, it occurs a decrease of CXCR2 receptors expression at neutrophil plasma membrane. This reduction is related to an excessive G protein coupled receptor kinases (GRK2) activation, which are responsible for CXCR2 receptor internalization, resulting, this way, a failure at neutrophil migration to infection focus (STADTMANN; ZARBOCK, 2012). At smooth muscle cells, there are alpha-1 adrenoceptors, which are G protein coupled receptors (GPCRs). These receptors signaling are related to pathways of induction of myocardial contractility and blood vases (LI et al., 2019). Nevertheless, at septic condition, there is a lack of inflammation control and exacerbated increase of catecholamines at blood flow. These catecholamines bind to alpha-1 receptors and also activate GRK2, which are recruited from cytosol to plasma membrane and phosphorylate GPCRs (LERMAN; KIM, 2015). Next, ²-arrestin binds to the phosphorylated receptor, decouples it and drives it to endocytosis, this way internalizing smooth muscle alpha1 receptors (WANG et al., 2007). A new studied concept at pharmacology involves the term "biased agonism". This concept involves the ligand-receptor complex, which the agonist may activate a signaling pathway in detriment of another one (RAJAGOPAL; RAJAGOPAL; LEFKOWITZ, 2010). That way, we search to investigate possible biased agonists to alpha1 G coupled receptors pathway activation in detriment of ²-arrestin pathway, aiming at cardiac function improvement. Paroxetin has been identified to be capable of selectively inhibiting GRK2 activity. This drug binds directly to the kinase domain of GRK2 and prevents your activity. This way, paroxetine was capable of increasing myocardial contractility (THAL et al., 2012). Previous studies executed by our laboratory group allowed to see that paroxetin is capable of decrease CXCR2 receptor internalization at HEK-293 cells, utilizing bioluminescence resonance energy transfer technique (BRET). That way, this work looks to investigate paroxetine therapeutic potential at neutrophil migration recovery, by GRK2 inhibition to reduce CXCR2 internalization and increase chemokine responsiveness at septic model. This work also looks to investigate paroxetine therapeutic potential at cardiac function improvement, also by GRK2 inhibition to decrease alpha1 adrenoceptors internalization and increase catecholamines responsiveness; in sum, we also search to investigate the potential of biased agonists to alpha1 G coupled adrenoceptors (for example A61603 and norepinephrine), aiming to evaluate the favoring of intracellular calcium mobilization related pathway at microvasculature cells. (AU)