Avaliação do papel do inflamassoma NLRP3 no dano cardíaco desencadeado por cocaína

Abstract

Cocaine dependence negatively affects the quality of life and working capacity of users and is associated with increased public costs for treating dependents. Peripherally, cocaine blocks the reuptake of noradrenaline through the norepinephrine transporter (NET), increasing its availability in the synaptic cleft and exacerbating its effects on the heart. In addition to increased activation of adrenergic receptors, cocaine activates NF-κB and the expression of pro-inflammatory cytokines, such as IL-1β and IL-18, as well as the production of reactive oxygen species (ROS). These are key events in the activation of the NLRP3 inflammasome, an intracellular platform that culminates in caspase-1 activation and is involved in the pathophysiology of several cardiovascular diseases. Despite this evidence, there has not yet been a demonstration of the involvement of the NLRP3 inflammasome in cocaine-induced cardiac damage. For this purpose, C57BL/6 mice were given cocaine (15 mg/kg/day; i.p) for either 5 days or 15 days to assess cardiac morphometry and non-invasive systolic blood pressure (SBP) monitoring. Cocaine was observed to induce an increase in heart weight, septal wall thickening, and cardiomyocyte hypertrophy at both time points. SBP increased only after 15 days of cocaine exposure. Thus, the study focused on characterizing cardiac changes after 5 days of cocaine exposure. At this time point, although cocaine did not induce fibrosis and caused only subtle changes in the electrocardiogram, elevated basal contractility was observed in isolated hearts, with a reduced response to pharmacological stress by β-adrenergic agonists. Additionally, there was a reduction in antioxidant barriers, evidenced by a decrease in SOD and catalase activities, combined with an increase in ROS, measured by fluorescent probe (DHE), and activation of the NLRP3 inflammasome, determined by a fluorescent probe for active caspase-1 (FAM-FLICA). Thus, to determine the role of the NLRP3 inflammasome, animals treated with cocaine were given the drugs MCC950 (20 mg/kg/day; i.p) and glibenclamide (20 mg/kg/day; p.o). In addition to preventing cardiac, cellular hypertrophy, and septal remodeling, NLRP3 inflammasome inhibition prevented contractility changes, both ex vivo and in isolated cardiomyocytes. Furthermore, inflammasome inhibition prevented the reduction in calcium transients, the increase in IL-1β gene expression, and the increase in ROS concentration and caspase-1 activity induced by cocaine. Some of these findings were confirmed in NLRP3 and caspase-1 knockout (KO) mice treated with cocaine, in which prevention of cardiac hypertrophy and reduction in antioxidant capacity was observed. Finally, to confirm the involvement of adrenergic receptors in cocaine's cardiac effects, a group was treated with carvedilol (20 mg/kg/day; i.p), an α- and β dual receptor blocker . It was observed that carvedilol, in addition to mimicking the effects of NLRP3 inflammasome inhibitors by preventing cardiac and cellular hypertrophy, basal hypercontractility, and reduced ex vivo adrenergic response, inhibited NLRP3 inflammasome activation induced by cocaine. In conclusion, NLRP3 inflammasome plays a role in cocaine-induced cardiac damage, and treatments with NLRP3 inflammasome inhibitors prevent this injury. NLRP3 inflammasome activation by cocaine is mediated by adrenergic receptor stimulation, as combined α- and β-receptor blockage inhibited NLRP3 inflammasome activity and prevented cocaine-induced cardiac damage.