Radical-containing ultrafine particulate matter initiates epithelial-to-mesenchymal transitions in airway epithelial cells.

Environmentally persistent free radicals (EPFRs) in combustion-generated particulate matter (PM) are capable of inducing pulmonary pathologies and contributing to the development of environmental asthma. In vivo exposure of infant rats to EPFRs demonstrates their ability to induce airway hyperresponsiveness to methacholine, a hallmark of asthma. However, the mechanisms by which combustion-derived EPFRs elicit in vivo responses remain elusive. In this study, we used a chemically defined EPFR consisting of approximately 0.2 µm amorphrous silica containing 3% cupric oxide with the organic pollutant 1,2-dichlorobenzene (DCB-230). DCB-230 possesses similar radical content to urban-collected EPFRs but offers several advantages, including lack of contaminants and chemical uniformity. DCB-230 was readily taken up by BEAS-2B and at high doses (200 µg/cm(2)) caused substantial necrosis. At low doses (20 µg/cm(2)), DCB-230 particles caused lysosomal membrane permeabilization, oxidative stress, and lipid peroxidation within 24 hours of exposure. During this period, BEAS-2B underwent epithelial-to-mesenchymal transition (EMT), including loss of epithelial cell morphology, decreased E-cadherin expression, and increased α-smooth muscle actin (α-SMA) and collagen I production. Similar results were observed in neonatal air-liquid interface culture (i.e., disruption of epithelial integrity and EMT). Acute exposure of infant mice to DCB-230 resulted in EMT, as confirmed by lineage tracing studies and evidenced by coexpression of epithelial E-cadherin and mesenchymal α-SMA proteins in airway cells and increased SNAI1 expression in the lungs. EMT in neonatal mouse lungs after EPFR exposure may provide an explanation for epidemiological evidence supporting PM exposure and increased risk of asthma.

Immunomodulation with IL-4R alpha antisense oligonucleotide prevents respiratory syncytial virus-mediated pulmonary disease.

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in infants worldwide. Severe RSV infections in infants cause bronchiolitis, wheeze, and/or cough and significantly increase the risk for developing asthma. RSV pathogenesis is thought to be due to a Th2-type immune response initiated in response to RSV infection, specifically in the infant. Using a neonatal mouse system as an appropriate model for human infants, we sought to determine whether local inhibition of IL-4Rα expression during primary RSV infection in the neonate would prevent Th2-skewed responses to secondary RSV infection and improve long-term pulmonary function. To reduce IL-4Rα expression, antisense oligonucleotides (ASOs) specific for IL-4Rα were administered intranasally to neonatal mice at the time of primary infection. Mice were initially infected with RSV at 1 wk of age and were reinfected at 6 wk of age. Administration of IL-4Rα ASOs during primary RSV infection in neonatal mice abolished the pulmonary dysfunction normally observed following reinfection in the adult. This ablation of pulmonary dysfunction correlated with a persistent rebalancing of the Th cell compartment with decreased Th2 responses (i.e., reduced goblet cell hyperplasia, Th2 cells, and cytokine secretion) and increased Th1 responses (i.e., elevated Th1 cell numbers and type I Abs and cytokines). Our data support our hypothesis that a reduction in the Th2 immune response during primary infection in neonates prevents Th2-mediated pulmonary pathology initially and upon reinfection and further suggest that vaccine strategies incorporating IL-4Rα ASOs may be of significant benefit to infants.

Modulation of lung inflammation by vessel dilator in a mouse model of allergic asthma.

BACKGROUND: Atrial natriuretic peptide (ANP) and its receptor, NPRA, have been extensively studied in terms of cardiovascular effects. We have found that the ANP-NPRA signaling pathway is also involved in airway allergic inflammation and asthma. ANP, a C-terminal peptide (amino acid 99-126) of pro-atrial natriuretic factor (proANF) and a recombinant peptide, NP73-102 (amino acid 73-102 of proANF) have been reported to induce bronchoprotective effects in a mouse model of allergic asthma. In this report, we evaluated the effects of vessel dilator (VD), another N-terminal natriuretic peptide covering amino acids 31-67 of proANF, on acute lung inflammation in a mouse model of allergic asthma. METHODS: A549 cells were transfected with pVD or the pVAX1 control plasmid and cells were collected 24 hrs after transfection to analyze the effect of VD on inactivation of the extracellular-signal regulated receptor kinase (ERK1/2) through western blot. Luciferase assay, western blot and RT-PCR were also performed to analyze the effect of VD on NPRA expression. For determination of VD's attenuation of lung inflammation, BALB/c mice were sensitized and challenged with ovalbumin and then treated intranasally with chitosan nanoparticles containing pVD. Parameters of airway inflammation, such as airway hyperreactivity, proinflammatory cytokine levels, eosinophil recruitment and lung histopathology were compared with control mice receiving nanoparticles containing pVAX1 control plasmid. RESULTS: pVD nanoparticles inactivated ERK1/2 and downregulated NPRA expression in vitro, and intranasal treatment with pVD nanoparticles protected mice from airway inflammation. CONCLUSION: VD's modulation of airway inflammation may result from its inactivation of ERK1/2 and downregulation of NPRA expression. Chitosan nanoparticles containing pVD may be therapeutically effective in preventing allergic airway inflammation.