Autoantibodies Neutralizing Type I IFNs in the Bronchoalveolar Lavage of at Least 10% of Patients During Life-Threatening COVID-19 Pneumonia.

Autoantibodies (auto-Abs) neutralizing type I interferons (IFNs) are found in the blood of at least 15% of unvaccinated patients with life-threatening COVID-19 pneumonia. We report here the presence of auto-Abs neutralizing type I IFNs in the bronchoalveolar lavage (BAL) of 54 of the 415 unvaccinated patients (13%) with life-threatening COVID-19 pneumonia tested. The 54 individuals with neutralizing auto-Abs in the BAL included 45 (11%) with auto-Abs against IFN-α2, 37 (9%) with auto-Abs against IFN-ω, 54 (13%) with auto-Abs against IFN-α2 and/or ω, and five (1%) with auto-Abs against IFN-ß, including three (0.7%) with auto-Abs neutralizing IFN-α2, IFN-ω, and IFN-ß, and two (0.5%) with auto-Abs neutralizing IFN-α2 and IFN-ß. Auto-Abs against IFN-α2 also neutralize the other 12 subtypes of IFN-α. Paired plasma samples were available for 95 patients. All seven patients with paired samples who had detectable auto-Abs in BAL also had detectable auto-Abs in plasma, and one patient had auto-Abs detectable only in blood. Auto-Abs neutralizing type I IFNs are, therefore, present in the alveolar space of at least 10% of patients with life-threatening COVID-19 pneumonia. These findings suggest that these auto-Abs impair type I IFN immunity in the lower respiratory tract, thereby contributing to hypoxemic COVID-19 pneumonia.

Assessing and improving the validity of COVID-19 autopsy studies - A multicentre approach to establish essential standards for immunohistochemical and ultrastructural analyses.

BACKGROUND: Autopsy studies have provided valuable insights into the pathophysiology of COVID-19. Controversies remain about whether the clinical presentation is due to direct organ damage by SARS-CoV-2 or secondary effects, such as overshooting immune response. SARS-CoV-2 detection in tissues by RT-qPCR and immunohistochemistry (IHC) or electron microscopy (EM) can help answer these questions, but a comprehensive evaluation of these applications is missing. METHODS: We assessed publications using IHC and EM for SARS-CoV-2 detection in autopsy tissues. We systematically evaluated commercially available antibodies against the SARS-CoV-2 proteins in cultured cell lines and COVID-19 autopsy tissues. In a multicentre study, we evaluated specificity, reproducibility, and inter-observer variability of SARS-CoV-2 IHC. We correlated RT-qPCR viral tissue loads with semiquantitative IHC scoring. We used qualitative and quantitative EM analyses to refine criteria for ultrastructural identification of SARS-CoV-2. FINDINGS: Publications show high variability in detection and interpretation of SARS-CoV-2 abundance in autopsy tissues by IHC or EM. We show that IHC using antibodies against SARS-CoV-2 nucleocapsid yields the highest sensitivity and specificity. We found a positive correlation between presence of viral proteins by IHC and RT-qPCR-determined SARS-CoV-2 viral RNA load (N= 35; r=-0.83, p-value <0.0001). For EM, we refined criteria for virus identification and provide recommendations for optimized sampling and analysis. 135 of 144 publications misinterpret cellular structures as virus using EM or show only insufficient data. We provide publicly accessible digitized EM sections as a reference and for training purposes. INTERPRETATION: Since detection of SARS-CoV-2 in human autopsy tissues by IHC and EM is difficult and frequently incorrect, we propose criteria for a re-evaluation of available data and guidance for further investigations of direct organ effects by SARS-CoV-2. FUNDING: German Federal Ministry of Health, German Federal Ministry of Education and Research, Berlin University Alliance, German Research Foundation, German Center for Infectious Research.

Cytological patterns of bronchoalveolar lavage fluid in mechanically ventilated COVID-19 patients on extracorporeal membrane oxygenation.

INTRODUCTION: Coronavirus disease-2019 (COVID-19) may lead to acute respiratory distress syndrome requiring extracorporeal membrane oxygenation (ECMO). Patterns of inflammatory bronchoalveolar cells in COVID-19 patients treated with ECMO are not well described. OBJECTIVE: We aimed to describe inflammatory cell subpopulations in blood and bronchoalveolar lavages (BALs) obtained in critically ill COVID-19 patients shortly after ECMO implementation. METHODS: BAL was performed in the middle lobe in 12 consecutive ECMO-treated COVID-19 patients. Trained cytologists analyzed peripheral blood and BAL cells using flow cytometry and routine staining, respectively. Data were interpreted in relation to dexamethasone administration and weaning from ECMO and ventilator. RESULTS: High neutrophil proportions (66% to 88% of total cells) were observed in the absence of bacterial superinfection and more frequently in dexamethasone-free patients (83% [82-85] vs. 29% [8-68], P = 0.006), suggesting that viral infection could be responsible of predominantly neutrophilic lung inflammation. Successful weaning from ECMO/ventilator could not be predicted by the peripheral white blood and BAL cell pattern. CONCLUSION: High neutrophil proportions can be observed in critically ill COVID-19 patients despite the lack of microbiological evidence on BAL of bacterial superinfection. Dexamethasone was associated with lower neutrophil proportions in BAL. Our study was probably underpowered to provide BAL cell pattern helpful to predict weaning from ECMO/ventilator.

[Histopathological features due to the SARS-CoV-2]. / Les lésions histologiques associées à l'infection par le SARS-CoV-2.

The infection due to the SARS-CoV-2 leads lesions mainly observed at the respiratory tract level, but not exclusively. The analyses of these lesions benefited from different autopsy studies. Thus, these lesions were observed in different organs, tissues and cells. These observations allowed us to rapidly improve the knowledge of the pathophysiological mechanisms associated with this emergent infectious disease. The virus can be detected in formalin fixed paraffin embedded tissues using immunohistochemistry, in situ hybridization, molecular biology and/or electron microscopy approaches. However, many uncertainties are still present concerning the direct role of the SARS-CoV-2 on the different lesions observed in different organs, outside the lung, such as the heart, the brain, the liver, the gastrointestinal tract, the kidney and the skin. In this context, it is pivotal to keep going to increase the different tissue and cellular studies in the COVID-19 positive patients aiming to better understanding the consequences of this new infectious disease, notably considering different epidemiological and co-morbidities associated factors. This could participate to the development of new therapeutic strategies too. The purpose of this review is to describe the main histological and cellular lesions associated with the infection due to the SARS-CoV-2.

Delayed acute myocarditis and COVID-19-related multisystem inflammatory syndrome.

Precise descriptions of coronavirus disease 2019 (COVID-19)-related cardiac damage as well as underlying mechanisms are scarce. We describe clinical presentation and diagnostic workup of acute myocarditis in a patient who had developed COVID-19 syndrome 1 month earlier. A healthy 40-year-old man suffered from typical COVID-19 symptoms. Four weeks later, he was admitted because of fever and tonsillitis. Blood tests showed major inflammation. Thoracic computed tomography was normal, and RT-PCR for SARS-CoV-2 on nasopharyngeal swab was negative. Because of haemodynamic worsening with both an increase in cardiac troponin and B-type natriuretic peptide levels and normal electrocardiogram, acute myocarditis was suspected. Cardiac echographic examination showed left ventricular ejection fraction at 45%. Exhaustive diagnostic workup included RT-PCR and serologies for infectious agents and autoimmune blood tests as well as cardiac magnetic resonance imaging and endomyocardial biopsies. Cardiac magnetic resonance with T2 mapping sequences showed evidence of myocardial inflammation and focal lateral subepicardial late gadolinium enhancement. Pathological analysis exhibited interstitial oedema, small foci of necrosis, and infiltrates composed of plasmocytes, T-lymphocytes, and mainly CD163+ macrophages. These findings led to the diagnosis of acute lympho-plasmo-histiocytic myocarditis. There was no evidence of viral RNA within myocardium. The only positive viral serology was for SARS-CoV-2. The patient and his cardiac function recovered in the next few days without use of anti-inflammatory or antiviral drugs. This case highlights that systemic inflammation associated with acute myocarditis can be delayed up to 1 month after initial SARS-CoV-2 infection and can be resolved spontaneously.