Differential Susceptibilities of Human Lung Primary Cells to H1N1 Influenza Viruses

Abstract

Human alveolar epithelial cells (AECs) and alveolar macrophages (AMs) are the first lines of lung defense. Here, we report that AECs are the direct targets for H1N1 viruses that have circulated since the 2009 pandemic (H1N1pdm09). AMs are less susceptible to H1N1pdm09 virus, but they produce significantly more inflammatory cytokines than AECs from the same donor. AECs form an intact epithelial barrier that is destroyed by H1N1pdm09 infection. However, there is significant variation in the cellular permissiveness to H1N1pdm09 infection among different donors. AECs from obese donors appear to be more susceptible to H1N1pdm09 infection, whereas gender, smoking history, and age do not appear to affect AEC susceptibility. There is also a difference in response to different strains of H1N1pdm09 viruses. Compared to A/California04/09 (CA04), A/New York/1682/09 (NY1682) is more infectious and causes more epithelial barrier injury, although it stimulates less cytokine production. We further determined that a single amino acid residue substitution in NY1682 hemagglutinin is responsible for the difference in infectivity. In conclusion, this is the first study of host susceptibility of human lung primary cells and the integrity of the alveolar epithelial barrier to influenza. Further elucidation of the mechanism of increased susceptibility of AECs from obese subjects may facilitate the development of novel protection strategies against influenza virus infection. IMPORTANCEDisease susceptibility of influenza is determined by host and viral factors. Human alveolar epithelial cells (AECs) form the key line of lung defenses against pathogens. Using primary AECs from different donors, we provided cellular level evidence that obesity might be a risk factor for increased susceptibility to influenza. We also compared the infections of two closely related 2009 pandemic H1N1 strains in AECs from the same donor and identified a key viral factor that affected host susceptibility, the dominance of which may be correlated with disease epidemiology. In addition, primary human AECs can serve as a convenient and powerful model to investigate the mechanism of influenza-induced lung injury and determine the effect of genetic and epigenetic factors on host susceptibility to pandemic influenza virus infection.

Antioxidant Defenses of Francisella tularensis Modulate Macrophage Function and Production of Proinflammatory Cytokines

“…We believe that these variations may have been due to variability in monocytes obtained from blood donors. Consistent with our findings, several previous studies have also reported that variability in susceptibility to infection and/or innate immune responses may arise due to variations in genetic and epigenetic background of each blood donor (71)(72)(73).…”

AIM2 Inflammasome Is Critical for Influenza-Induced Lung Injury and Mortality

“…Several studies have reported a detrimental role for IL-1b for severe influenza infections (36)(37)(38). We recently also reported that IL-1b treatment reduces the transepithelial electrical resistance of human primary alveolar epithelial cells and leads to epithelial barrier injury (19). In this study, accompanied by the striking reduction in inflammasome activation (Figs.…”

“…Deidentified patient lungs that were not suitable for transplantation and donated for medical research were obtained through the International Institute for the Advancement of Medicine (Edison, NJ) and the Airway Epithelial Core at the University of Pittsburgh as we described previously (17,19 , and wild-type (WT) C57BL/6J mice were purchased from The Jackson Laboratory (Bar Harbor, ME); ASC 2/2 mice were from Genentech (San Francisco, CA). All mice were bred inhouse, and AIM2 2/2 mice were further backcrossed with C57BL/6J mice for two more generations.…”

“…Human ATII cells and AMs were isolated from deidentified donor lungs and cultured as we described previously (17,19). Mouse ATII cells from ageand sex-matched WT and AIM2 2/2 mice were isolated as previously described (21) and plated in DMEM with 5% rat serum in 37˚C incubator with 5% CO2 for 2 d, and then cultured with 1% charcoal-stripped FBS plus 10 ng/ml keratinocyte growth factor (R&D Systems, Minneapolis, MN) for 4 d preinfection.…”

“…Both viruses were propagated in MDCK cells as previously described (19); the concentration of viruses were titrated using plaque assay as previously described (17,19). In addition, LD 50 was determined according to Reed and Muench's method (20).…”