Host–Pathogen Responses to Pandemic Influenza H1N1pdm09 in a Human Respiratory Airway Model

Abstract

The respiratory Influenza A Viruses (IAVs) and emerging zoonotic viruses such as Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pose a significant threat to human health. To accelerate our understanding of the host–pathogen response to respiratory viruses, the use of more complex in vitro systems such as normal human bronchial epithelial (NHBE) cell culture models has gained prominence as an alternative to animal models. NHBE cells were differentiated under air-liquid interface (ALI) conditions to form an in vitro pseudostratified epithelium. The responses of well-differentiated (wd) NHBE cells were examined following infection with the 2009 pandemic Influenza A/H1N1pdm09 strain or following challenge with the dsRNA mimic, poly(I:C). At 30 h postinfection with H1N1pdm09, the integrity of the airway epithelium was severely impaired and apical junction complex damage was exhibited by the disassembly of zona occludens-1 (ZO-1) from the cell cytoskeleton. wdNHBE cells produced an innate immune response to IAV-infection with increased transcription of pro- and anti-inflammatory cytokines and chemokines and the antiviral viperin but reduced expression of the mucin-encoding MUC5B, which may impair mucociliary clearance. Poly(I:C) produced similar responses to IAV, with the exception of MUC5B expression which was more than 3-fold higher than for control cells. This study demonstrates that wdNHBE cells are an appropriate ex-vivo model system to investigate the pathogenesis of respiratory viruses.

Airway tight junctions as targets of viral infections

“…In another study, differentiated AECs cells were infected with 2009 pandemic Influenza A/H1N1pdm09 strain. 31 There was evidence of a decline in barrier function, with a marked decrease in TEER and increase in permeability. They showed a decrease of ZO-1 and the F-actin cytoskeleton, as well as cell death following viral infection and barrier dysfunction.…”

“… 98 Many cytokines and chemokines were secreted in infected cells, with a significant increase in IL-6, TNF-α, and IL-8, suggesting activation of anti-viral inflammatory responses. 31 Further research is needed to determine if the increased cytokine production is independent of or a result of AJC disruption. Another study used two strains of H1N1pdm09 viruses, A/California04/09 (CA04), and A/New York/1682/09 (NY1682), to infect human alveolar type II epithelial cells.…”

In vitro characterisation of SARS‐CoV‐2 and susceptibility of domestic ferrets ( Mustela putorius furo )

“…SARS‐CoV‐2 VIC01 grew reliably in wdNHBE cells, with peak titres >10 6 TCID 50 /mL at 48–72 hr post‐infection, consistent with previous studies (Zhu et al., 2020). The sporadic nature of SARS‐CoV‐2 infection in the ex vivo airway epithelium and the lack of effect of SARS‐CoV‐2 on barrier integrity at 96 hr post‐infection, as assessed by TEER readings, provided a striking contrast to influenza virus which infects most cells and damages the in vitro epithelium within 24 hr (Pharo et al., 2020). The observations with SARS‐CoV‐2 VIC01 are consistent with those previously reported for SARS‐CoV (Sims et al., 2005).…”

“…Commercially sourced undifferentiated normal human bronchial epithelial (NHBE) cells (Lonza Group) were expanded and differentiated as previously described (Pharo et al., 2020). Passage 3 NHBE cells were seeded on the apical surface of a 6.5‐mm‐diameter Transwell polyester membrane (Corning, Inc) pre‐coated with 5 µg/cm 2 Collagen I Rat Protein, Tail (Thermo Fisher Scientific) and incubated at 37°C/5% CO 2 .…”

Animal Models Utilized for the Development of Influenza Virus Vaccines

“…Advances in the safety and immunogenicity of universal influenza virus vaccine candidates has reinvigorated the human challenge model [ 92 , 245 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 , 267 , 268 , 269 , 270 ]. Human challenge studies are conducted by immunizing participants with vaccine candidates and monitoring for any side effects or adverse reactions.…”