Infecção por beta coronavirus desencadeia disfunção vascular, falência circulatória e morte em camundongos via TNF/NF-κB/iNOS

Abstract

Scientific evidence indicates that SARS-CoV-2 affects the cardiovascular system, leading to unsatisfactory clinical outcomes. However, the pathophysiological mechanisms underlying vascular dysfunctions, and associated hemodynamic alterations and lethality, are not understood. Thus, we aim at investigating the mechanisms involved the vascular dysfunction induced by the infection with the betacoronavirus MHV-3 and SARS-Cov-2. Wild-type C57BL/6, iNOS-/-, gp91phox-/-, and TNFR1-/- mice were infected with MHV-3, and K18-hACE2 transgenic mice with SARS-CoV-2, by nasal instillation. The thoracic aorta, mesenteric artery, and inferior vena cava were used for vascular reactivity experiments. Immunofluorescence was used to study expression of target proteins associated with inflammation and tissue damage. Spray plethysmography and Doppler were used to assess systolic blood pressure (SBP) and flow, respectively. Quantification of nitric oxide (NO) and reactive oxygen species (ROS) production was performed using fluorescent probes (DAF and DHE, respectively). ELISA was used to assess inflammatory cytokine production. Survival curves were estimated using the Kaplan-Meier method. In wild-type mice, MHV3 infection induced a decrease in the contractile response to phenylephrine in the aorta and vena cava, which was associated with decreased arterial blood pressure and blood flow, and death. Conversely, contractility in resistance mesenteric arteries was increased. In the aorta, removal of the endothelium, pharmacological inhibition of inducible nitric oxide synthase (iNOS) with 1400w, genetic deletion of iNOS (iNOS-/-), and scavenging of NO with carboxy-PTIO, normalized the contractile response. The endothelium-dependent relaxant response to acetylcholine in the aorta was decreased by MHV-3 infection. Scavenging of superoxide anions with tiron and genetic deletion of the gp91phox subunit of NADPH oxidase (gp91phox-/-) restored vasodilation. Nasal MHV-3 instillation resulted in direct infection of the aorta, and TNF production was increased in both plasma and vascular tissue. The expressions of iNOS and NF-kB, and the basal production of NO and ROS, were increased MHV-3 and SARS-CoV-2 infection. MHV-3 infection of TNFR1-/- animals prevented vascular dysfunctions, hemodynamics changes, the expressions of iNOS and NF-kB, and the basal production of NO and ROS, and death were increased MHV-3 and SARS-CoV-2 infection. In conclusion, pulmonary infection with beta coronaviruses triggers an acute endothelium-dependent decrease in contractility in large arteries and veins, which leads to circulatory failure, and death via a TNF/NF-κB/iNOS-dependent mechanism. Beta coronaviruses infection also induces oxidative stress associated with decrease in NO-endothelium-dependent vascular relaxation via TNF/gp91phox/superoxide pathway. The later mechanism is a common pathophysiological feature of the main comorbidities associated with COVID-19 and may explain many of the clinical manifestations of post-covid conditions.