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Pulmonary Vascular Endothelialitis, Thrombosis, and Angiogenesis in Covid-19.

Authors :: Ackermann M
Verleden SE
Kuehnel M
Haverich A
Welte T
Laenger F
Vanstapel A
Werlein C
Stark H
Tzankov A
Li WW
Li VW
Mentzer SJ
Jonigk D
Source :: The New England journal of medicine [N Engl J Med] 2020 Jul 09; Vol. 383 (2), pp. 120-128. Date of Electronic Publication: 2020 May 21.
Publication Year :: 2020
Abstract: Background: Progressive respiratory failure is the primary cause of death in the coronavirus disease 2019 (Covid-19) pandemic. Despite widespread interest in the pathophysiology of the disease, relatively little is known about the associated morphologic and molecular changes in the peripheral lung of patients who die from Covid-19.<br />Methods: We examined 7 lungs obtained during autopsy from patients who died from Covid-19 and compared them with 7 lungs obtained during autopsy from patients who died from acute respiratory distress syndrome (ARDS) secondary to influenza A(H1N1) infection and 10 age-matched, uninfected control lungs. The lungs were studied with the use of seven-color immunohistochemical analysis, micro-computed tomographic imaging, scanning electron microscopy, corrosion casting, and direct multiplexed measurement of gene expression.<br />Results: In patients who died from Covid-19-associated or influenza-associated respiratory failure, the histologic pattern in the peripheral lung was diffuse alveolar damage with perivascular T-cell infiltration. The lungs from patients with Covid-19 also showed distinctive vascular features, consisting of severe endothelial injury associated with the presence of intracellular virus and disrupted cell membranes. Histologic analysis of pulmonary vessels in patients with Covid-19 showed widespread thrombosis with microangiopathy. Alveolar capillary microthrombi were 9 times as prevalent in patients with Covid-19 as in patients with influenza (P<0.001). In lungs from patients with Covid-19, the amount of new vessel growth - predominantly through a mechanism of intussusceptive angiogenesis - was 2.7 times as high as that in the lungs from patients with influenza (P<0.001).<br />Conclusions: In our small series, vascular angiogenesis distinguished the pulmonary pathobiology of Covid-19 from that of equally severe influenza virus infection. The universality and clinical implications of our observations require further research to define. (Funded by the National Institutes of Health and others.).<br /> (Copyright © 2020 Massachusetts Medical Society.)