In severe SARS-CoV-2 infections, emerging data including recent histopathological studies have emphasized the crucial role of endothelial cells (ECs) in vascular dysfunction, immunothrombosis, and inflammation. Histopathological studies have evidenced direct viral infection of ECs, endotheliitis with diffuse endothelial inflammation, and micro-and macrovascular thrombosis both in the venous and arterial circulations. Venous thrombotic events, particularly pulmonary embolism, with elevated D-dimer and coagulation activation are highly prevalent in COVID-19 patients. The pro-inflammatory cytokine storm, with elevated levels of interleukin-6 (IL-6), IL-2 receptor, and tumor necrosis factor-α, could also participate in endothelial dysfunction and leukocyte recruitment in the microvasculature. COVID-19-induced endotheliitis may explain the systemic impaired microcirculatory function in different organs in COVID-19 patients. Ongoing trials directly and indirectly target COVID-19-related endothelial dysfunctions: i.e., a virus-cell entry using recombinant angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS-2) blockade, coagulation activation, and immunomodulatory therapies, such as anti-IL-6 strategies. Studies focusing on endothelial dysfunction in COVID-19 patients are warranted as to decipher their precise role in severe SARS-CoV-2 infection and organ dysfunction and to identify targets for further interventions.

Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website.Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

No abstract

We are currently facing a frightening increase in COVID-19 patients admitted to the ICU. Aiming at screening for fungal secondary pneumonia, we collected the data of our first 27 ICU patients, who underwent bronchoalveolar lavage or bronchial aspirates. We classified the patients based on the recently published study on invasive aspergillosis in influenza patients in your journal (Schauwvlinghe et al., 2018.) and found 33% of our COVID-19 patients with putative invasive pulmonary aspergillosis. Observing such a high prevalence in COVID-infected patients was somehow unexpected since the 30% prevalence of invasive aspergillosis in influenza patients has been attributed to the action of oseltamivir on anti-Aspergillus immunity. Almost all critically ill COVID-19 patients develop ARDS and are likely to receive high-dose steroids or immunomodulatory therapies to prevent worsening as suggested by reports from China. In the COVID-19 patients with putative invasive aspergillosis, antifungal prophylactic therapy may be questioned to avoid increased lung inflammation that may compromise the outcome. This issue remains to be addressed in future clinical trials. We are strongly convinced that testing deep lung specimens for Aspergillus in severe COVID-19 patients should be recommended. This message is major, given the high mortality rate of COVID-19 patients in the ICU.

BackgroundThe pathophysiology of AKI during tumor lysis syndrome (TLS) is not well understood due to the paucity of data. We aimed to decipher crystal-dependent and crystal-independent mechanisms of TLS-induced AKI.MethodsCrystalluria, plasma cytokine levels, and extracellular histones levels were measured in two cohorts of patients with TLS. We developed a model of TLS in syngeneic mice with acute myeloid leukemia, and analyzed ultrastructural changes in kidneys and endothelial permeability using intravital confocal microscopy. In parallel, we studied the endothelial toxicity of extracellular histones in vitro.ResultsThe study provides the first evidence that previously described crystal-dependent mechanisms are insufficient to explain TLS-induced AKI. Extracellular histones that are released in huge amounts during TLS caused profound endothelial alterations in the mouse model. The mechanisms of histone-mediated damage implicates endothelial cell activation mediated by Toll-like receptor 4. Heparin inhibits extracellular histones and mitigates endothelial dysfunction during TLS.ConclusionThis study sheds new light on the pathophysiology of TLS-induced AKI and suggests that extracellular histones may constitute a novel target for therapeutic intervention in TLS when endothelial dysfunction occurs.

Introduction: Diagnosis of COVID-19 associated pulmonary aspergillosis remains unclear especially in non-immunocompromised patients. The aim of this study was to evaluate seven mycological criteria and their combination in a large homogenous cohort of patients. Methods: All successive patients (n=176) hospitalized for COVID-19 requiring mechanical ventilation and who clinically worsened despite appropriate standard of care were included over a one-year period. Direct examination, culture, Aspergillus qPCR ( Af -qPCR) and galactomannan was performed on all respiratory samples (n=350). Serum galactomannan, ß-D-glucan and plasma Af -qPCR were also assessed. Criteria were analyzed alone or in combination in relation to mortality rate. Results: Mortality was significantly different in patients with 0, ≤2 and ≥3 positive criteria (logrank test, p=0.04) with death rate of 43.1, 58.1 and 76.4% respectively. Direct examination, plasma qPCR and serum galactomannan were associated with a 100% mortality rate. Bronchoalveolar lavage (BAL) galactomannan and positive respiratory sample culture were often found as isolated markers (28.1 and 34.1%) and poorly repeatable when a second sample was obtained. Aspergillus DNA was detected in 13.1% of samples (46/350) with significantly lower Cq when associated with at least one other criteria (30.2 vs 35.8) (p<0.001). Conclusion: Combination of markers and/or blood biomarkers and/or direct respiratory sample examination seems more likely to identify patients with CAPA. Af -qPCR may help identifying false positive results of BAL galactomannan testing and culture on respiratory samples while quantifying fungal burden accurately.

Acute respiratory distress syndrome (ARDS) is the most severe complication of COVID-19, a disease caused by severe acute respiratory syndrome coronavirus (SARS CoV) 2. The mechanisms underlying the progression from asymptomatic disease to pneumonia and ARDS are complex and by far unelucidated. As for bacterial sepsis, the release of damage associated molecular patterns and pathogen associated molecular patterns triggers activation of the complement cascade. Subsequently, overexpressed anaphylatoxins recruit inflammatory cells in the lung and other organs and contribute initiating and amplifying a vicious circle of thromboinflammation causing organs damage and eventually death. Preclinical and observational studies in patients with COVID-19 provided evidence that complement inhibition effectively may attenuate lung and systemic inflammation, restore the coagulation/ fibrinolysis balance, improve organs function and eventually may save life. Ongoing Phase 2/3 trials should elucidate the benefit to risk profile of complement inhibitors and may clarify the optimal targets in the complement cascade.

No abstract