COVID-19 Infections in Adults with Congenital Heart Disease-A Prospective Single-Center Study in an Outpatient Setting.

BACKGROUND: COVID-19 might pose a risk for adults with congenital heart disease (ACHD). However, data regarding the rate of infection as well as myocardial involvement in ACHD patients are currently lacking. METHODS: During the study period from January to June 2021, all consecutive outpatients from our ACHD clinic were eligible to participate. Clinical data were collected. An antibody test for COVID-19 was performed in all patients. Cardiovascular magnetic resonance imaging (CMR) was offered to those with a positive antibody test. RESULTS: Overall, 420 patients (44.8% female, mean age 36.4 ± 11.6 years) participated. Congenital heart defect (CHD) complexity was simple in 96 (22.9%), moderate in 186 (44.3%), complex in 117 (27.9%), and miscellaneous in 21 (5.0%) patients. Altogether, 28 (6.7%) patients had a positive antibody test. Out of these, 14 had an asymptomatic course. The others had mainly mild symptoms and were managed as outpatients. Furthermore, 11 patients (39.3%) had even not been aware of their infection. Fourteen patients underwent a CMR without signs of myocardial involvement in any of them. CONCLUSIONS: We observed a number of undetected cases of COVID-19 infections in our ACHD population. Reassuringly, in all cases, the infection had a mild clinical course.

Robust Preanalytical Performance of Soluble PD-1, PD-L1 and PD-L2 Assessed by Sensitive ELISAs in Blood.

The interaction between programmed death-1 receptor PD-1 and its ligands PD-L1 and PD-L2 is involved in self-tolerance, immune escape of cancer, cardiovascular diseases, and COVID-19. As blood-based protein markers they bear great potential to improve oncoimmunology research and monitoring of anti-cancer immunotherapy. A variety of preanalytical conditions were tested to assure high quality plasma sample measurements: (i) different time intervals and storage temperatures before and after blood centrifugation; (ii) fresh samples and repeated freeze-thaw-cycles; (iii) different conditions of sample preparation before measurement. Concerning short-term stability, acceptable recoveries for PD-1 between 80 and 120% were obtained when samples were kept up to 24 h at 4 and 25 °C before and after blood centrifugation. Similarly, recoveries for PD-L2 were acceptable for 24 h at 4 °C and 6 h at 25 °C before blood centrifugation and up to 24 h at 4 and 25 °C after centrifugation. Variations for PD-L1 were somewhat higher, however, at very low signal levels. Sample concentrations (ng/mL) were neither affected by the freezing process nor by repeated freeze-thaw cycles with coefficients of variation for PD-1: 9.1%, PD-L1 6.8%, and PD-L2 4.8%. All three biomarkers showed good stability regarding preanalytic conditions of sample handling enabling reliable and reproducible quantification in oncoimmunology research and clinical settings of anti-cancer immunotherapy.

Recruitment of highly cytotoxic CD8+ T cell receptors in mild SARS-CoV-2 infection.

T cell immunity is crucial for control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and has been studied widely on a quantitative level. However, the quality of responses, in particular of CD8+ T cells, has only been investigated marginally so far. Here, we isolate T cell receptor (TCR) repertoires specific for immunodominant SARS-CoV-2 epitopes restricted to common human Leukocyte antigen (HLA) class I molecules in convalescent individuals. SARS-CoV-2-specific CD8+ T cells are detected up to 12 months after infection. TCR repertoires are diverse, with heterogeneous functional avidity and cytotoxicity toward virus-infected cells, as demonstrated for TCR-engineered T cells. High TCR functionality correlates with gene signatures that, remarkably, could be retrieved for each epitope:HLA combination analyzed. Overall, our data demonstrate that polyclonal and highly functional CD8+ TCRs-classic features of protective immunity-are recruited upon mild SARS-CoV-2 infection, providing tools to assess the quality of and potentially restore functional CD8+ T cell immunity.

Circulating Nucleosomes as Potential Markers to Monitor COVID-19 Disease Progression.

The severity of coronavirus disease 2019 (COVID-19) varies significantly with cases spanning from asymptomatic to lethal with a subset of individuals developing Severe Acute Respiratory Syndrome (SARS) and death from respiratory failure. To determine whether global nucleosome and citrullinated nucleosome levels were elevated in COVID-19 patients, we tested two independent cohorts of COVID-19 positive patients with quantitative nucleosome immunoassays and found that nucleosomes were highly elevated in plasma of COVID-19 patients with a severe course of the disease relative to healthy controls and that both histone 3.1 variant and citrullinated nucleosomes increase with disease severity. Elevated citrullination of circulating nucleosomes is indicative of neutrophil extracellular trap formation, neutrophil activation and NETosis in severely affected individuals. Importantly, using hospital setting (outpatient, inpatient or ICU) as a proxy for disease severity, nucleosome levels increased with disease severity and may serve as a guiding biomarker for treatment. Owing to the limited availability of mechanical ventilators and extracorporal membrane oxygenation (ECMO) equipment, there is an urgent need for effective tools to rapidly assess disease severity and guide treatment selection. Based on our studies of two independent cohorts of COVID-19 patients from Belgium and Germany, we suggest further investigation of circulating nucleosomes and citrullination as biomarkers for clinical triage, treatment allocation and clinical drug discovery.

SARS-CoV-2 antibody testing-questions to be asked.

Severe acute respiratory syndrome coronavirus 2 infection and development of coronavirus disease 2019 presents a major health care challenge of global dimensions. Laboratory diagnostics of infected patients, and the assessment of immunity against severe acute respiratory syndrome coronavirus 2, presents a major cornerstone in handling the pandemic. Currently, there is an increase in demand for antibody testing and a large number of tests are already marketed or are in the late stage of development. However, the interpretation of test results depends on many variables and factors, including sensitivity, specificity, potential cross-reactivity and cross-protectivity, the diagnostic value of antibodies of different isotypes, and the use of antibody testing in identification of acutely ill patients or in epidemiological settings. In this article, the recently established COVID-19 Task Force of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) addresses these issues on the basis of currently available data sets in this rapidly moving field.