Priv.-Doz. Dr. med. Rainer B. Zotz.

It is with great sadness and deep grief that we received news about the sudden death of Priv.-Doz. Dr. Rainer Bernd Zotz (Fig. 1). He was torn out of life on September 26, 2022 by suffering from an acute illness. As his long-standing mentor and colleague, it is my sad duty to write this obituary.

Post-COVID Syndrome in Adults-An Overview.

This article provides an overview of various aspects related to post-COVID syndrome. Apart from its prevalence, symptoms and sequelae, risk determinants, and psychosocial implications, the pathogenesis of post-COVID condition is discussed in more detail. A focus on thrombo-inflammation in SARS-CoV-2 infection, the role of neutrophil extracellular traps, and the prevalence of venous thromboembolism is made. Moreover, COVID-19 and post-COVID syndrome in immunocompromising conditions, and the impact of vaccination on the prevention and treatment of post-COVID symptoms are reviewed. Autoimmunity is a hallmark of post-COVID syndrome, and, therefore, is another focus of this article. Thus, misdirected cellular and humoral immune responses can enhance the risk of latent autoimmunity in post-COVID syndrome. Facing the high prevalence of COVID-19 cases worldwide, it can be assumed that autoimmune disorders will increase globally over the next few years. Recent advances in identifying genetically determined variants may open the avenue for a better understanding of the susceptibility to and severity of SARS-CoV-2 infection and post-COVID syndrome.

Cardiac Arrhythmias in Post-COVID Syndrome: Prevalence, Pathology, Diagnosis, and Treatment.

An increase in post-COVID patients with late sequelae of acute COVID-19 infection is emerging as an ongoing challenge for physicians and healthcare professionals. Since the beginning of the pandemic, it has rapidly become evident that the acute infection is not limited to the respiratory tract but that several organs, including the cardiovascular system, can be affected. Moreover, in a significant proportion of patients (ranging from about 10 to up to 50%) with former COVID-19, cardiopulmonary symptoms such as dyspnea, palpitations, restricted physical capacity, and cardiac arrhythmias can persist weeks and months after the acute SARS-CoV-2 infection. The spectrum of COVID-19-associated arrhythmias is rather wide, most likely due to various pathomechanisms. In this article, the prevalence of cardiac arrhythmias and underlying pathologies are reviewed, including direct myocardial injury and abnormal consequences with an impact on cardiac electric instability. The hyperinflammatory reaction of the host immune system is specifically considered. Moreover, several distinct rhythm disorders occurring in post-COVID patients are discussed with regard to their clinical management.

Early SARS-CoV-2 infection: Platelet-neutrophil complexes and platelet function.

Background: Conflicting results have been reported on platelet activity ex vivo and responsiveness in vitro among patients with COVID-19 with or without thromboembolic complications. Objectives: To assess platelet reactivity in patients with moderate disease at early stages of COVID-19. Methods: We performed a prospective, descriptive analysis of 100 consecutive patients presenting with suspected SARS-CoV-2 infection at University Medical Center Freiburg during the first or second wave of the pandemic. Following polymerase chain reaction testing and compliance with study inclusion criteria, 20 SARS-CoV-2-positive and 55 SARS-CoV-2-negative patients (serving as patient controls) were enrolled. In addition, 15 healthy subjects were included. Platelet reactivity was assessed using whole-blood impedance aggregometry and flow cytometry in response to various agonists. Results: Platelet aggregation was significantly impaired in the patients with COVID-19 compared with that in the patient controls or healthy subjects. The reduced platelet responsiveness in the patients with COVID-19 was associated with impaired activation of GPIIb/IIIa (αIIbß3). In contrast, low expression of P-selectin at baseline and intact secretion upon stimulation in vitro suggest that no preactivation in vivo, leading to "exhausted" platelets, had occurred. The proportion of circulating platelet-neutrophil complexes was significantly higher in the patients with COVID-19 (mean ± SD, 41% ± 13%) than in the patient controls (18% ± 7%; 95% CI, 11.1-34.1; P = .0002) or healthy subjects (17% ± 4%; 95% CI, 13.8-33.8; P < .0001). An analysis of neutrophil adhesion receptors revealed upregulation of CD11b (α-subunit of αMß2) and CD66b (CEACAM8) but not of CD162 (PSGL-1) in the patients with COVID-19. Conclusion: Despite reduced platelet responsiveness, platelet-neutrophil complexes are increased at early stages of moderate disease. Thus, this cellular interaction may occur during COVID-19 without preceding platelet activation.

COVID-19: Cardio-pulmonary and Vascular Manifestations.

The COVID-19 pandemic is still threatening us, our patients, and the global health care system. Since the first outbreak at the end of 2019 in China, it became rapidly clear that a new variant of a SARS virus, SARS-CoV-2, is threatening our human society worldwide. Since then, the scientific community has accumulated an incredibly large amount of knowledge about the pathophysiology of this virus, primarily affecting the respiratory tract and, in severe cases, subsequently resulting in acute respiratory distress syndrome and multiple organ failure due to uncontrolled systemic inflammatory response syndrome.1 2.

NLRP3 Inflammasome Assembly in Neutrophils Is Supported by PAD4 and Promotes NETosis Under Sterile Conditions.

Neutrophil extracellular trap formation (NETosis) and the NLR family pyrin domain containing 3 (NLRP3) inflammasome assembly are associated with a similar spectrum of human disorders. While NETosis is known to be regulated by peptidylarginine deiminase 4 (PAD4), the role of the NLRP3 inflammasome in NETosis was not addressed. Here, we establish that under sterile conditions the cannonical NLRP3 inflammasome participates in NETosis. We show apoptosis-associated speck-like protein containing a CARD (ASC) speck assembly and caspase-1 cleavage in stimulated mouse neutrophils without LPS priming. PAD4 was needed for optimal NLRP3 inflammasome assembly by regulating NLRP3 and ASC protein levels post-transcriptionally. Genetic ablation of NLRP3 signaling resulted in impaired NET formation, because NLRP3 supported both nuclear envelope and plasma membrane rupture. Pharmacological inhibition of NLRP3 in either mouse or human neutrophils also diminished NETosis. Finally, NLRP3 deficiency resulted in a lower density of NETs in thrombi produced by a stenosis-induced mouse model of deep vein thrombosis. Altogether, our results indicate a PAD4-dependent formation of the NLRP3 inflammasome in neutrophils and implicate NLRP3 in NETosis under noninfectious conditions in vitro and in vivo.

Thrombocytopenia and Hemostatic Changes in Acute and Chronic Liver Disease: Pathophysiology, Clinical and Laboratory Features, and Management.

Thrombocytopenia, defined as a platelet count <150,000/µL, is the most common complication of advanced liver disease or cirrhosis with an incidence of up to 75%. A decrease in platelet count can be the first presenting sign and tends to be proportionally related to the severity of hepatic failure. The pathophysiology of thrombocytopenia in liver disease is multifactorial, including (i) splenomegaly and subsequently increased splenic sequestration of circulating platelets, (ii) reduced hepatic synthesis of thrombopoietin with missing stimulation both of megakaryocytopoiesis and thrombocytopoiesis, resulting in diminished platelet production and release from the bone marrow, and (iii) increased platelet destruction or consumption. Among these pathologies, the decrease in thrombopoietin synthesis has been identified as a central mechanism. Two newly licensed oral thrombopoietin mimetics/receptor agonists, avatrombopag and lusutrombopag, are now available for targeted treatment of thrombocytopenia in patients with advanced liver disease, who are undergoing invasive procedures. This review summarizes recent advances in the understanding of defective but at low level rebalanced hemostasis in stable cirrhosis, discusses clinical consequences and persistent controversial issues related to the inherent bleeding risk, and is focused on a risk-adapted management of thrombocytopenia in patients with chronic liver disease, including a restrictive transfusion regimen.

Diagnosis and Management of Vaccine-Related Thrombosis following AstraZeneca COVID-19 Vaccination: Guidance Statement from the GTH.

The COVID-19 pandemic is an ongoing global healthcare crisis. Based on reports of atypically located thromboses following vaccination with the AstraZeneca COVID-19 vaccine, the Society of Thrombosis and Haemostasis Research (GTH) has issued guidance statements on the recognition, diagnosis, and treatment of this rare complication. It shares pathophysiological features with heparin-induced thrombocytopenia (HIT) and is referred to as vaccine-induced prothrombotic immune thrombocytopenia (VIPIT).

Hemostasis Laboratory Diagnostics: Characteristics, Communication Issues, and Current Challenges Resulting from Centralization of Laboratory Medicine.

Laboratory diagnostics of patients with bleeding and thrombotic disorders can be a delicate task, which requires special skills and expertise. In this article, characteristic features of hemostasis testing are reviewed, including staged protocols and synoptic assessment of the patient history, clinical symptoms, and laboratory findings. Despite major progress in the diagnostic and therapeutic management, centralized testing of hemostasis can be associated with substantial challenges, resulting from the current dissociation between the clinical and laboratory world. To address some of these challenges, possible solutions are discussed, including adaptation of an established working paradigm.

About mentees and mentors: what kind of advanced training should young scientists receive? - A personal reflection.

Comprehensive training of talented MD or PhD students and postdoctoral fellows is one of the essential requirements for a future career as an established investigator or even an outstanding scientist. Here, from personal experience, several relevant aspects are summarized including the high responsibility of the academic mentor. Specifically, the interaction of the mentor with fellows, the choice of the research project, and the impact of the mentor's personality on mentees are discussed.