Human nasal and lung tissues infectedex vivowith SARS-CoV-2 provide insights into differential tissue-specific and virus-specific innate immune responses in the upper and lower respiratory tract

Abstract

The nasal-mucosa constitutes the primary entry site for respiratory viruses including SARS-CoV-2. While the imbalanced innate immune response of end-stage COVID-19 has been extensively studied, the earliest stages of SARS-CoV-2 infection at the mucosal entry site have remained unexplored. Here we employed SARS-CoV-2 and influenza virus infection in native multi-cell-type human nasal turbinate and lung tissues ex vivo, coupled with genome-wide transcriptional analysis, to investigate viral susceptibility and early patterns of local-mucosal innate immune response in the authentic milieu of the human respiratory tract. SARS-CoV-2 productively infected the nasal turbinate tissues, predominantly targeting respiratory epithelial cells, with rapid increase in tissue-associated viral sub-genomic mRNA, and secretion of infectious viral progeny. Importantly, SARS-CoV-2 infection triggered robust antiviral and inflammatory innate immune responses in the nasal mucosa. The upregulation of interferon stimulated genes, cytokines and chemokines, related to interferon signaling and immune-cell activation pathways, was broader than that triggered by influenza virus infection. Conversely, lung tissues exhibited a restricted innate immune response to SARS-CoV-2, with a conspicuous lack of type I and III interferon upregulation, contrasting with their vigorous innate immune response to influenza virus. Our findings reveal differential tissue-specific innate immune responses in the upper and lower respiratory tract, that are distinct to SARS-CoV-2. The studies shed light on the role of the nasal-mucosa in active viral transmission and immune defense, implying a window of opportunity for early interventions, whereas the restricted innate immune response in early-SARS-CoV-2-infected lung tissues could underlie the unique uncontrolled late-phase lung damage of advanced COVID-19.

Timing of SARS-CoV-2 vaccination during the third trimester of pregnancy and transplacental antibody transfer: a prospective cohort study

“…Briefly, serial two‐fold dilutions of heat-inactivated serum samples (starting from 1:10; diluted in Dulbecco’s modified Eagle’s medium in a total volume of 50 μL) were incubated with an equal volume of viral solution, containing 100 median tissue culture infectious doses (TCID 50 ) of SARS-CoV-2 isolate USA-WA1/2020 (NR-52281; obtained from BEI Resources, Manassas, VA, USA), for 1 hour in a 96-well plate (at 37°C in humidified atmosphere with 5% CO 2 ). The serum–virus mixtures (100 μL; eight replicates of each serum dilution) were then added to a 96-well plate containing a semi‐confluent VERO E6 cell monolayer (ATCC CRL-1586; maintained as described previously [ 18 ]). Following 3 days of incubation (at 37°C in a humidified atmosphere with 5% CO 2 ), the cells in each well were scored for viral cytopathic effect.…”

Early versus late third trimester maternal SARS-CoV-2 BNT162b2 mRNA immunization maximizes transplacental antibody transfer and neonatal neutralizing antibody levels

“…Briefly, serial two□fold dilutions of heat inactivated serum samples (starting from 1:10; diluted in DMEM in a total volume of 50 μl) were incubated with an equal volume of viral solution, containing 100 tissue culture infectious dose (TCID50) of SARS-CoV-2 isolate USA-WA1/2020 (NR-52281; obtained from BEI resources), for 1 □hour in a 96-well plate (at 37°C in humidified atmosphere with 5% CO 2 ). The serum-virus mixtures (100□µL; 8 replicates of each serum dilution) were then added to a 96-well plate containing a semi□confluent VERO E6 cell monolayer (ATCC CRL-1586; maintained as described [22]). Following 3 days of incubation (at 37°C in a humidified atmosphere with 5% CO 2 ), the cells in each well were scored for viral cytopathic effect (CPE).…”

Type I interferons and SARS-CoV-2: from cells to organisms

“…SARS-CoV-2 is highly sensitive to pretreatment with type I IFNs [ 50 , 63 , 64 ]. Exogenous type I IFN does not seem to be inhibited by the virus [ 55 , 65 , 66 ].…”