SARS-CoV-2 is evolving with mutations in the receptor binding domain (RBD) being of particular concern. It is important to know how much cross-protection is offered between strains following vaccination or infection. Here, we obtain serum and saliva samples from groups of vaccinated (Pfizer BNT-162b2), infected and uninfected individuals and characterize the antibody response to RBD mutant strains. Vaccinated individuals have a robust humoral response after the second dose and have high IgG antibody titers in the saliva. Antibody responses however show considerable differences in binding to RBD mutants of emerging variants of concern and substantial reduction in RBD binding and neutralization is observed against a patient-isolated South African variant. Taken together our data reinforce the importance of the second dose of Pfizer BNT-162b2 to acquire high levels of neutralizing antibodies and high antibody titers in saliva suggest that vaccinated individuals may have reduced transmission potential. Substantially reduced neutralization for the South African variant further highlights the importance of surveillance strategies to detect new variants and targeting these in future vaccines.
Abstract Thromboembolic events are frequently reported in patients infected with the SARS-CoV-2 virus. However, the exact mechanisms of thromboembolic events remain elusive. In this work, we show that immunoglobulin G (IgG) subclass in patients with COVID-19 trigger the formation of procoagulant PLTs in a Fc-gamma-RIIA (FcγRIIA) dependent pathway leading to increased thrombus formation in vitro. Most importantly, these events were significantly inhibited via FcγRIIA blockade as well as by the elevation of PLTs’ intracellular cyclic-adenosine-monophosphate (cAMP) levels by the clinical used agent Iloprost. The novel findings of FcγRIIA mediated prothrombotic conditions in terms of procoagulant PLTs leading to higher thrombus formation as well as the successful inhibition of these events via Iloprost could be promising for the future treatment of the complex coagulopathy observed in COVID-19 disease. Key points - Fc-gamma-receptor IIA mediated PS externalization on the PLT surface triggers increased thrombus formation - Inductors of cAMP inhibit antibody-mediated thrombus formation and may have potential therapeutic advantage in COVID-19
Critical conditions such as sepsis following infection or traumatic injury disturb the complex state of homeostasis that may lead to uncontrolled inflammation resulting in organ failure, shock and death. They are associated with endogenous mediators that control the onset of acute inflammatory response, but the central problem remains the complete resolution of inflammation. Omega-3 enriched lipid emulsions (Ω-3+ LEs) were used in experimental studies and clinical trials to establish homeostasis, yet with little understanding about their role on the resolution of inflammation and tissue regeneration. Here, we demonstrate that Ω-3 lipid emulsions (LEs) orchestrate inflammation-resolution/regeneration mechanism during sterile peritonitis and murine polymicrobial sepsis. Ω-3+ LEs recessed neutrophil infiltration, reduced pro-inflammatory mediators, reduced the classical monocyte and enhanced the non-classical monocytes/macrophages recruitment and finally increased the efferocytosis in sepsis. The actions of Ω-3+ LE were 5-lipoxygenase (5-LOX) and 12/15-lipoxygenase (12/15-LOX) dependent. Ω-3+ LEs shortened the resolution interval by 56%, stimulated the endogenous biosynthesis of resolution mediators lipoxin A4, protectin DX and maresin 1 and contributed to tissue regeneration. Ω-3+ LEs protected against hypothermia and weight loss and enhanced survival in murine polymicrobial sepsis. We highlighted a role of Ω-3+ LEs in regulating key mechanisms within the resolution terrain during murine sepsis. This might form the basis for a rational design of sepsis specific clinical nutrition.
A 53-yr-old woman with a left ventricular assist device (LVAD), placed 4 mo before admission for idiopathic dilated cardiomyopathy, was awaiting heart transplantation. She was found unresponsive at home with low cardiac output from her LVAD. No signs of fractures or thoracic bruising were present and she did not require chest compressions for resuscitation. During transport to the hospital, she was tracheally intubated, started on inotropic drugs, and transferred directly to the operating room on arrival to the hospital for surgical evaluation. Transesophageal echocardiography (TEE) was performed in the operating room to evaluate the patient’s critical condition. TEE demonstrated a fluid collection adjacent to the right ventricle (RV) in the midesophageal four-chamber view at 0° and midesophageal long axis view at 87° rotation (Fig. 1, video clip 1; please see video clip available at www.anesthesia-analgesia.org). The LVAD inflow cannula in the left ventricle did not show any signs of obstruction or malpositioning, the LVAD outflow cannula in the aorta was not visible on TEE, although TEE is an ideal technique for evaluating LVAD placement and function.1 A drain was placed percutaneously via a subxiphoid approach under TEE guidance by visualizing the position of the paracentesis cannula in the fluid cavity. The patient remained hemodynamically unstable with continuing drainage of a large amount of blood. Further inspection on TEE with color flow Doppler revealed a communication between the fluid cavity and the RV (Fig. 2, top). Pulsed wave Doppler identified flow from the RV into the RV dissection cavity (Fig. 2, bottom). Cardiopulmonary bypass was initiated via cannulation of the femoral vessels. During surgical exploration, the RV was found to be dissected in a large portion, producing an intramural pocket. Therefore, the surgical finding confirmed the primary diagnosis made on TEE. The RV was considered irreparable by the surgeon because of the large ventricular dissection in conjunction with extremely friable myocardial tissue. The patient’s overall detrimental condition before surgery in conjunction with an irreparable RV resulted in the decision to discontinue cardiopulmonary bypass and declare the patient dead. Postmortem autopsy confirmed the surgical finding of an intramural RV dissection.Figure 1.: Midesophageal four-chamber view at 0° rotation demonstrating a fluid filled cavity (*) adjacent to the right ventricle (RV) (top). The same fluid collection (*) is demonstrated in the midesophageal long-axis view at 87° rotation (bottom). LA = left atrium.Figure 2.: Color Doppler demonstrating flow from the RV cavity to the dissection cavity (*) (top). Pulsed wave Doppler placed at the communication of the RV cavity with the dissection demonstrates flow between the two cavities (bottom). LA = left atrium.RV dissection is infrequent, and can result from myocardial infarction, coronary artery balloon angioplasty, thrombolytic therapy, cardiac operation, or chest trauma.2,3 It may also occur spontaneously with unknown etiology.4 The differential diagnosis for RV fluid collection includes pericardial hematoma, RV rupture and pseudoaneurysm of the RV. An echocardiographic feature of RV dissection is an intramyocardial hypoechoic cavity that is contained between an intact endocardium and epicardium communicating with the ventricular cavity. The shape of this neocavity reflects the tendency to dissect along the spiral myocardial fibers and the dissection hematoma is entirely within the myocardium. TEE is able to diagnose a RV dissection by identifying an entry and/or exit site of the dissection cavity. However, the diagnosis is often only possible on surgical exploration. Preoperatively, the communication between the RV and the dissection cavity might be difficult to identify with transthoracic echocardiography, computed tomography, or magnetic resonance imaging, and can be misdiagnosed for a subepicardial hematoma or pseudoaneurysm. A pseudoaneurysm occurs when the rupture is contained by an overlying adherent pericardium with a high propensity to rupture. In contrast to a RV dissection, TEE demonstrates myocardial rupture with disruption of the endocardium and/or epicardium in patients with pseudoaneurysm. Pseudoaneurysms are often associated with thrombi and pericardial effusions, particularly in the inferior and inferoposterior segments of the left ventricle due to the solitary blood supply in this region of the heart. In addition, subepicardial hematoma might result from an unrecognized coronary artery perforation during percutaneous coronary intervention. A subepicardial hematoma is a pseudoaneurysm with the containing wall composed of intact epicardium, sometimes with a thin myocardial layer; the hematoma is contained entirely within the myocardium.5 The blood within the hematoma originates either from the ventricular cavity or is of intramural origin. Subepicardial hematoma demonstrates as an echo-free space between the ventricular muscle and the pericardium.6 Intramural RV dissection or RV hematoma often results in dismal patient outcome due to tamponade of the ventricular cavity and the associated tamponade physiology.7 The presented case demonstrates the role of echocardiography in the diagnosis of pericardial and intramural pathology in hemodynamically instable patients, since demonstration of a communication of the ventricular cavity with a dissection is often not possible on TEE.
Hepatic ischemia/reperfusion (I/R) is a major adverse reaction to liver transplantation, hemorrhagic shock, or resection. Recently, the anti‐inflammatory properties of the axonal guidance cue netrin‐1 were reported. Here, we demonstrate that netrin‐1 also impacts the resolution of inflammation and promotes hepatic repair and regeneration during liver I/R injury. In initial studies, we investigated the induction of netrin‐1 and its receptors in murine liver tissues after I/R injury. Hepatic I/R injury was performed in mice with a partial genetic netrin‐1 deficiency (Ntn1 +/− ) or wild‐type C57BL/6 treated with exogenous netrin‐1 to examine the endogenous and therapeutically administered impact of netrin‐1. These investigations were corroborated by studies determining the characteristics of intravascular leukocyte flow, clearance of apoptotic neutrophils (polymorphonuclear cells [PMNs]), production of specialized proresolving lipid mediators (SPMs), generation of specific growth factors contributing to the resolution of inflammation, and liver repair. Hepatic I/R was associated with a significant reduction of netrin‐1 transcript and protein in murine liver tissue. Subsequent studies in netrin‐1‐deficient mice revealed lower efficacies in reducing PMN infiltration, proinflammatory cytokine levels, and hepatic‐specific injury enzymes. Conversely, mice treated with exogenous netrin‐1 exhibited increased liver protection and repair, reducing neutrophil influx into the injury site, decreasing proinflammatory mediators, increasing efferocytosis of apoptotic PMNs, and stimulating local endogenous biosynthesis of SPMs and the generation of specific growth factors. Finally, genetic studies implicated the A2B adenosine receptor in netrin‐1‐mediated protection during hepatic I/R injury. Conclusion: The present study indicates a previously unrecognized role for netrin‐1 in liver protection and its contribution to tissue homeostasis and regeneration. (H epatology 2016;63:1689‐1705)
Abstract Background Accumulating evidence indicates toward an association between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and procoagulatory state in blood. Thromboelastographic investigations are useful point-of-care devices to assess coagulation and fibrinolysis. Objectives We investigated the hypothesis that the procoagulatory state in COVID-19 patients is associated with impaired fibrinolysis system. Methods Altogether, 29 COVID-19 patients admitted to normal wards or to the intensive care unit (ICU) were included in this descriptive study. Whole blood samples were investigated by thromboelastography to assess coagulation and fibrinolysis. Additionally, standard routine coagulation testing and immunoassays for factors of fibrinolysis as plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), plasminogen activity and α2-antiplasmin (A2AP) were performed. Results A significantly increased lysis resistance and a significantly longer time of lysis after adding tissue plasminogen activator were observed in blood samples from ICU COVID-19 patients compared with healthy controls (maximal lysis: 3.25 ± 0.56 vs. 6.20 ± 0.89%, p = 0.0127; lysis time: 365.7 ± 44.6 vs. 193.2 ± 16.3 seconds, p = 0.0014). PAI-1 activity was significantly higher in plasma samples of ICU COVID-19 patients (PAI-1: 4.92 ± 0.91 vs. 1.28 ± 0.33 U/mL, p = 0.001). A positive correlation between the activity of PAI-1 and lysis time of the formed clot (r = 0.70, p = 0.0006) was observed. Conclusion Our data suggest that severe SARS-CoV-2 infection is associated with impaired fibrinolytic activity in blood, where fibrinolytic inhibitors are elevated leading to an increased resistance to clot lysis. Thromboelastography could offer a tool to investigate the contribution of the fibrinolytic status to the procoagulatory condition in COVID-19.
Die Anwendungssicherheit von Blut- und Plasmakomponenten konnte in den letzten Jahrzehnten enorm gesteigert werden. Darüber hinaus ist der Umgang mit Blut und Blutprodukten seit einigen Jahren in den Querschnittsleitlinien zur Therapie mit Blutkomponenten und Plasmaderivaten der Bundesärztekammer festgelegt. Diese liegen bereits in der 4. Revision vor und werden laufend an den aktuellen Stand der Wissenschaft angepasst. Ziel des vorliegenden Artikels ist es, den Inhalt der Querschnittsleitlinien in Bezug auf Indikationen zur Transfusion (physiologische und Hb-gebundene Transfusionstrigger), der Auswahl des Erythrozytenkonzentrats und der häufigsten Nebenwirkungen zusammenzufassen.
Rationale: Acute lung injury (ALI) is an inflammatory disorder characterized by hypoxemia and diffuse infiltration of neutrophils into the alveolar space. The migration and extravasation of neutrophils is guided through positive guidance cues, such as chemokines. Recent work has identified the neuronal guidance protein netrin-1 to be a negative guidance cue for leukocyte migration and to hold antiinflammatory potential.Objectives: To test the role of pulmonary netrin-1 during ALI.Methods: Pulmonary netrin-1 expression was evaluated during acute inflammation in vitro and in vivo; the netrin-1 promoter was studied using pGL4 luciferase reporter. ALI was induced through LPS inhalation and mechanical ventilation in wild-type, Ntn1+/−, and A2BAR−/− animals. Exogenous netrin-1 was used to evaluate its impact on pulmonary inflammation.Measurements and Main Results: Wild-type animals demonstrated repression of pulmonary netrin-1 after LPS inhalation. In vitro studies confirmed the repression of netrin-1. Studies in the putative netrin-1 promoter identified a nuclear factor-κB–dependent mechanism to be involved in this repression. Ntn1+/− animals demonstrated increased inflammatory changes after LPS inhalation compared with Ntn1+/+ animals. Reconstitution with netrin-1 dampened the infiltration of neutrophils and cytokine production in the alveolar space. This effect was dependent on the adenosine 2b receptor. The importance of netrin-1 for the control of pulmonary inflammation could be corroborated in a model of ventilator-induced lung injury.Conclusions: Pulmonary netrin-1 levels are repressed during ALI. This results in pronounced pulmonary damage, an increased infiltration of neutrophils, and increased pulmonary inflammation. Exogenous netrin-1 significantly dampens the extent of ALI through the adenosine 2B receptor.
