Infection of cultured human tracheal epithelial cells by human parainfluenza virus types 2 and 3

Comparative primary paediatric nasal epithelial cell culture differentiation and RSV-induced cytopathogenesis following culture in two commercial media

The culture of differentiated human airway epithelial cells allows the study of pathogen-host interactions and innate immune responses in a physiologically relevant in vitro model. As the use of primary cell culture has gained popularity the availability of the reagents needed to generate these cultures has increased. In this study we assessed two different media, Promocell and PneumaCult, during the differentiation and maintenance of well-differentiated primary nasal epithelial cell cultures (WD-PNECs). We compared and contrasted the consequences of these media on WD-PNEC morphological and physiological characteristics and their responses to respiratory syncytial virus (RSV) infection. We found that cultures generated using PneumaCult resulted in greater total numbers of smaller, tightly packed, pseudostratified cells. However, cultures from both media resulted in similar proportions of ciliated and goblet cells. There were no differences in RSV growth kinetics, although more ciliated cells were infected in the PneumaCult cultures. There was also significantly more IL-29/IFNλ1 secreted from PneumaCult compared to Promocell cultures following infection. In conclusion, the type of medium used for the differentiation of primary human airway epithelial cells may impact experimental results.

Magnitude of influenza virus replication and cell damage is associated with interleukin-6 production in primary cultures of human tracheal epithelium

Primary cultures of human tracheal epithelium were infected with influenza viruses to examine the relationships between the magnitude of viral replication and infection-induced cell damage and cytokine production in airway epithelial cells. Infection with four strains of the type A influenza virus increased the detached cell number and lactate dehydrogenase (LDH) levels in the supernatants. The detached cell number and LDH levels were related to the viral titers and interleukin (IL)-6 levels and the nuclear factor kappa B (NF-κB) p65 activation. Treatment of the cells with an anti-IL-6 receptor antibody and an NF-κB inhibitor, caffeic acid phenethyl ester, reduced the detached cell number, viral titers and the LDH levels and improved cell viability after infection with the pandemic influenza virus [A/Sendai-H/N0633/2009 (H1N1) pdm09]. A caspase-3 inhibitor, benzyloxycarbonyl-DEVD-fluoromethyl ketone, reduced the detached cell number and viral titers. Influenza viral infection-induced cell damage may be partly related to the magnitude of viral replication, NF-κB-p65-mediated IL-6 production and caspase-3 activation.

Detection of enhanced neutrophil adhesion to parainfluenza-infected airway epithelial cells using a modified myeloperoxidase assay in a microtiter format

Despite growing evidence that respiratory virus infections precipitate episodes of airway obstruction and airway hyper-responsiveness in young children and in asthma, little information is available on the mechanisms by which virus infections alter the airway physiology. Airway inflammatory changes (including influx of inflammatory cells such as neutrophils) have been described during episodes of airway hyper-responsiveness in both animal models and human subjects. Neutrophil damage to several cell types has been shown to require adhesion as a primary step. In order to examine the potential interactions between virus-infected airway epithelial cells and neutrophils, we have studied the ability of neutrophils to adhere to virus-infected airway epithelial cell cultures. Neutrophil adherence was determined indirectly, using myeloperoxidase as a marker for adherent neutrophils in an assay system described here. Airway epithelial cell cultures (both primary human tracheal epithelial cells, and two permanent cell lines, A549 and BEAS-2B) were grown in 96-well tissue culture plates and infected with human parainfluenza virus type 2. Infected airway epithelial cell cultures supported significantly enhanced levels of neutrophil adherence (up to 50-75% of neutrophils added to the wells) compared to uninfected control cultures. Moreover, this adherence occurred in a virus dose-dependent fashion, with increasing levels of adherence noted at increasing viral multiplicities of infection. The assay system described allows the detection of small numbers of adherent neutrophils (as few as 1000 neutrophils) in a 96-well format.