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Eur Rev Med Pharmacol Sci ; 26(1): 270-277, 2022 01.
Article in English | MEDLINE | ID: covidwho-1631285


Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare new syndrome occurring after the ChAdOx1 nCoV-19 vaccine immunization. Patients with VITT are characterized by a variable clinical presentation, likewise also the outcome of these patients is very variable. Here we report the lung ultrastructural findings in the course of VITT of a 58-year-old male patient. Alveoli were mainly dilated, irregular in shape, and occupied by a reticular network of fibrin, while interalveolar septa appeared thickened. The proliferation of small capillaries gave rise to plexiform structures and pulmonary capillary hemangiomatosis-like features. Near the alveoli occupied by a dense fibrin network, the medium-sized arteries showed a modified wall and an intraluminal thrombus. This scenario looks quite similar to that found during COVID-19, where the lungs suffer from the attack of the antigen-antibodies complexes and the virus respectively. In both diseases, the final outcome is a severe inflammation, activation of the haemostatic system and fibrinolysis.

/adverse effects , Lung Injury/etiology , Lung Injury/pathology , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Vaccination/adverse effects , COVID-19/prevention & control , Fibrin , Humans , Lung Injury/diagnostic imaging , Lung Injury/immunology , Male , Microscopy, Electron, Scanning , Middle Aged , Parenchymal Tissue/pathology , Purpura, Thrombocytopenic, Idiopathic/diagnosis , Purpura, Thrombocytopenic, Idiopathic/immunology
Front Immunol ; 11: 1312, 2020.
Article in English | MEDLINE | ID: covidwho-615475


Respiratory, circulatory, and renal failure are among the gravest features of COVID-19 and are associated with a very high mortality rate. A common denominator of all affected organs is the expression of angiotensin-converting enzyme 2 (ACE2), a protease responsible for the conversion of Angiotensin 1-8 (Ang II) to Angiotensin 1-7 (Ang 1-7). Ang 1-7 acts on these tissues and in other target organs via Mas receptor (MasR), where it exerts beneficial effects, including vasodilation and suppression of inflammation and fibrosis, along an attenuation of cardiac and vascular remodeling. Unfortunately, ACE2 also serves as the binding receptor of SARS viral spike glycoprotein, enabling its attachment to host cells, with subsequent viral internalization and replication. Although numerous reports have linked the devastating organ injuries to viral homing and attachment to organ-specific cells widely expressing ACE2, little attention has been given to ACE-2 expressed by the immune system. Herein we outline potential adverse effects of SARS-CoV2 on macrophages and dendritic cells, key cells of the immune system expressing ACE2. Specifically, we propose a new hypothesis that, while macrophages play an important role in antiviral defense mechanisms, in the case of SARS-CoV, they may also serve as a Trojan horse, enabling viral anchoring specifically within the pulmonary parenchyma. It is tempting to assume that diverse expression of ACE2 in macrophages among individuals might govern the severity of SARS-CoV-2 infection. Moreover, reallocation of viral-containing macrophages migrating out of the lung to other tissues is theoretically plausible in the context of viral spread with the involvement of other organs.

Betacoronavirus/metabolism , Dendritic Cells/metabolism , Lung/pathology , Macrophages, Alveolar/metabolism , Peptidyl-Dipeptidase A/metabolism , Angiotensin-Converting Enzyme 2 , Betacoronavirus/immunology , COVID-19 , Coronavirus Infections/immunology , Coronavirus Infections/pathology , Dendritic Cells/immunology , Dendritic Cells/virology , Humans , Lung/virology , Macrophages, Alveolar/immunology , Macrophages, Alveolar/virology , Pandemics , Parenchymal Tissue/pathology , Parenchymal Tissue/virology , Pneumonia, Viral/immunology , Pneumonia, Viral/pathology , Receptors, Virus/metabolism , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism