SARS-CoV-2 is a new emerging coronavirus responsible for the Coronavirus Disease-19 (COVID-19) syndrome, declared a pandemic in March 2020 by WHO. This syndrome is characterized by an array of clinical manifestations ranging from fever and cough in mild conditions to pneumonia and Acute Respiratory Distress Syndrome (ARDS) in severe conditions, with the potential to be lethal particularly in fragile subjects. Macrophages are crucial components of innate immunity, which represent the first line of defense to pathogens. Considering their ability to regulate production of cytokines and growth factors in inflammatory conditions, they are likely involved in the cytokine storm that characterizes COVID-19 severe cases. Though a clear understanding on how macrophages directly sense and how they react to SARS-CoV-2 is crucial in order to better decipher COVID-19 pathogenesis, information available on these issues is limited. To dissect the direct effects of macrophage exposure to the virus, we isolated monocytes from buffy coats of healthy donors and differentiated them ex vivo to macrophages, which were then directly exposed to SARS-CoV-2 in vitro. In this experimental setting, we demonstrated that macrophages are susceptible to infection, as demonstrated by the analysis of genomic and subgenomic viral RNA, but not permissive for viral replication, as demonstrated by plaque assay. Though macrophages could not be exploited as a spreading platform by the virus, still they proved to be promptly activated after SARS-CoV-2 engagement, producing several of those cytokines involved in the cytokine storm that characterizes the most severe clinical manifestations of CIVID-19. On the opposite, macrophages were not supportive to the prototypical interferon-mediated antiviral response as neither type-I nor type-II interferon responses were evident. Finally, we demonstrated macrophage expression of the conventional viral entry protein ACE2, but also report evidence for ACE2-independent entry pathways in macrophages, as anti-ACE2 monoclonal antibodies efficiently blocked viral infection in conventional epithelial cells but not in this new SARS-CoV-2 target cell.
INFECTION OF MACROPHAGES BY SARS-COV-2: IMPLICATIONS FOR VIRAL SPREADING AND IMMUNE RESPONSE / S. Gianoli ; tutor: M. Locati ; director: N. Landsberger. Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, 2023 Apr 19. 35. ciclo, Anno Accademico 2022.
INFECTION OF MACROPHAGES BY SARS-COV-2: IMPLICATIONS FOR VIRAL SPREADING AND IMMUNE RESPONSE
S. Gianoli
2023
Abstract
SARS-CoV-2 is a new emerging coronavirus responsible for the Coronavirus Disease-19 (COVID-19) syndrome, declared a pandemic in March 2020 by WHO. This syndrome is characterized by an array of clinical manifestations ranging from fever and cough in mild conditions to pneumonia and Acute Respiratory Distress Syndrome (ARDS) in severe conditions, with the potential to be lethal particularly in fragile subjects. Macrophages are crucial components of innate immunity, which represent the first line of defense to pathogens. Considering their ability to regulate production of cytokines and growth factors in inflammatory conditions, they are likely involved in the cytokine storm that characterizes COVID-19 severe cases. Though a clear understanding on how macrophages directly sense and how they react to SARS-CoV-2 is crucial in order to better decipher COVID-19 pathogenesis, information available on these issues is limited. To dissect the direct effects of macrophage exposure to the virus, we isolated monocytes from buffy coats of healthy donors and differentiated them ex vivo to macrophages, which were then directly exposed to SARS-CoV-2 in vitro. In this experimental setting, we demonstrated that macrophages are susceptible to infection, as demonstrated by the analysis of genomic and subgenomic viral RNA, but not permissive for viral replication, as demonstrated by plaque assay. Though macrophages could not be exploited as a spreading platform by the virus, still they proved to be promptly activated after SARS-CoV-2 engagement, producing several of those cytokines involved in the cytokine storm that characterizes the most severe clinical manifestations of CIVID-19. On the opposite, macrophages were not supportive to the prototypical interferon-mediated antiviral response as neither type-I nor type-II interferon responses were evident. Finally, we demonstrated macrophage expression of the conventional viral entry protein ACE2, but also report evidence for ACE2-independent entry pathways in macrophages, as anti-ACE2 monoclonal antibodies efficiently blocked viral infection in conventional epithelial cells but not in this new SARS-CoV-2 target cell.File | Dimensione | Formato | |
---|---|---|---|
phd_unimi_R12496.pdf
Open Access dal 20/04/2024
Descrizione: Infection of macrophages by SARS-CoV-2: implications for viral spreading and immune response
Tipologia:
Pre-print (manoscritto inviato all'editore)
Dimensione
1.36 MB
Formato
Adobe PDF
|
1.36 MB | Adobe PDF | Visualizza/Apri |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.