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EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-321642


Background: A number of histopathological reports showed the presence of widespread thrombosis and associated morphology in pulmonary vessels of patients with COVID-19. Later, we identified vascular occlusions with neutrophils and neutrophil extracellular traps (NETs), as major components, in autopsy tissue from patients with COVID-19.Methods: We, here investigated 109 lung specimens from 17 patients with COVID-19 and compared them with 11 lung specimens from two patients who succumbed to pulmonary embolism and acute cardiac. Healthy lung specimens from four patients served as controls. We studied these autopsy lung specimens using immunohistochemistry and native endogenous fluorescence.Findings: We present a label-free imaging technique using native endogenous fluorescence that enables the visualization of occluded vessels. We demonstrate that native endogenous fluorescence identified occluded vessels in tissue specimens from patients with COVID-19.Interpretation: Label-free detection of occluded vessels enabled the detection of affected occluded vessels in lung specimens of patients with COVID-19 where the occluding components showed varying contents of neutrophil-derived materials.Funding Statement: Deutsche Forschungsgemeinschaft (DFG), EU, Volkswagen-StiftungDeclaration of Interests: All authors have no conflicts of interests to declare.Ethics Approval Statement: An institutional approval from each local Ethical Committee was obtained (permit #193_13B;permit # 174_20B;EK 092/20;EK 119/20;EK 460/20).

EBioMedicine ; 58: 102925, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-701831


BACKGROUND: Coronavirus induced disease 2019 (COVID-19) can be complicated by severe organ damage leading to dysfunction of the lungs and other organs. The processes that trigger organ damage in COVID-19 are incompletely understood. METHODS: Samples were donated from hospitalized patients. Sera, plasma, and autopsy-derived tissue sections were examined employing flow cytometry, enzyme-linked immunosorbent assays, and immunohistochemistry. PATIENT FINDINGS: Here, we show that severe COVID-19 is characterized by a highly pronounced formation of neutrophil extracellular traps (NETs) inside the micro-vessels. Intravascular aggregation of NETs leads to rapid occlusion of the affected vessels, disturbed microcirculation, and organ damage. In severe COVID-19, neutrophil granulocytes are strongly activated and adopt a so-called low-density phenotype, prone to spontaneously form NETs. In accordance, markers indicating NET turnover are consistently increased in COVID-19 and linked to disease severity. Histopathology of the lungs and other organs from COVID-19 patients showed congestions of numerous micro-vessels by aggregated NETs associated with endothelial damage. INTERPRETATION: These data suggest that organ dysfunction in severe COVID-19 is associated with excessive NET formation and vascular damage. FUNDING: Deutsche Forschungsgemeinschaft (DFG), EU, Volkswagen-Stiftung.

Coronavirus Infections/pathology , Extracellular Traps/metabolism , Microvessels/pathology , Neutrophils/metabolism , Pneumonia, Viral/pathology , Thrombosis/metabolism , COVID-19 , Cells, Cultured , Coronavirus Infections/complications , Coronavirus Infections/metabolism , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Humans , Microvessels/metabolism , Neutrophils/pathology , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/metabolism , Thrombosis/etiology , Thrombosis/pathology