Cinzia Maria Bellettato

The C-C chemokine receptors CCR4 and CCR8 identify airway T cells of allergen-challenged atopic asthmatics

In vitro polarized human Th2 cells preferentially express the chemokine receptors CCR3, CCR4, and CCR8 and migrate to their ligands: eotaxin, monocyte-derived chemokine (MDC), thymus- and activation-regulated chemokine (TARC), and I-309. We have studied the expression of chemokines and chemokine receptors in the airway mucosa of atopic asthmatics. Immunofluorescent analysis of endobronchial biopsies from six asthmatics, taken 24 hours after allergen challenge, demonstrates that virtually all T cells express IL-4 and CCR4. CCR8 is coexpressed with CCR4 on 28% of the T cells, while CCR3 is expressed on eosinophils but not on T cells. Expression of the CCR4-specific ligands MDC and TARC is strongly upregulated on airway epithelial cells upon allergen challenge, suggesting an involvement of this receptor/ligand axis in the regulation of lymphocyte recruitment into the asthmatic bronchi. In contrast to asthma, T cells infiltrating the airways of patients with chronic obstructive pulmonary disease and pulmonary sarcoidosis produce IFN-gamma and express high levels of CXCR3, while lacking CCR4 and CCR8 expression. These data support the role of CCR4, of its ligands MDC and TARC, and of CCR8 in the pathogenesis of allergen-induced late asthmatic responses and suggest that these molecules could be considered as targets for therapeutic intervention.

Expression of Programmed Death–1 Ligand (PD-L) 1, PD-L2, B7-H3, and Inducible Costimulator Ligand on Human Respiratory Tract Epithelial Cells and Regulation by Respiratory Syncytial Virus and Type 1 and 2 Cytokines

BACKGROUND Respiratory syncytial virus (RSV) is associated with wheezing illness, and infections can occur repeatedly throughout life. We hypothesized that RSV infection of respiratory tract epithelial cells up-regulates B7 molecules that regulate memory immune responses and that type 1 and 2 cytokines differentially modulate this induction. METHODS We used flow-cytometric analysis to investigate programmed death-1 ligand (PD-L) 1, PD-L2, B7-H3, and inducible costimulatory ligand (ICOS-L) expression on tracheal (NCI-H292), bronchial (BEAS-2B), and alveolar (A549) epithelial cells; regulation of this expression by RSV, interferon (IFN)- gamma , and interleukin (IL)-4; and the effects of IFN-gamma and IL-4 on RSV-induced expression of these molecules. RESULTS B7-H3 was strongly expressed, PD-L1 and ICOS-L were moderately expressed, and PD-L2 was weakly expressed on unstimulated tracheal, bronchial, and alveolar epithelial cells. RSV infection up-regulated PD-L1, PD-L2, and B7-H3 expression on all cells and ICOS-L expression on bronchial and alveolar epithelial cells. IL-4 treatment alone had no effect, whereas IFN-gamma treatment alone increased PD-L1 and PD-L2 expression on all cells and decreased B7-H3 expression on bronchial and alveolar epithelial cells. On RSV-infected alevolar epithelial cells, IFN-gamma treatment increased PD-L1 and PD-L2 expression and decreased B7-H3 and ICOS-L expression, and IL-4 treatment increased PD-L2 and B7-H3 expression and decreased ICOS-L expression. CONCLUSIONS Respiratory tract epithelial cells express a wide range of B7 molecules. RSV infection increases their expression, and this expression is differentially regulated by IFN-gamma and IL-4. These processes may be involved in decreasing T cell antiviral immune responses to RSV and in RSV-associated wheezing.

Reducing agents inhibit rhinovirus-induced up-regulation of the rhinovirus receptor intercellular adhesion molecule-1 (ICAM-1) in respiratory epithelial cells

Rhinoviruses are the major cause of common colds and of asthma exacerbations. Intercellular adhesion molecule‐1 (ICAM‐1) has a central role in airway inflammation and is the receptor for 90% of rhinoviruses. Rhinovirus infection of airway epithelium induces ICAM‐1. Because redox state is directly implicated in inflammatory responses via molecular signaling mechanisms, here we studied the effects of reducing agents on rhinovirus‐induced ICAM‐1 expression, mRNA up‐regulation, promoter activation, and nuclear factor activation. To investigate the effects of rhinovirus infection on the intracellular redox balance, we also studied whether rhinovirus infection triggers the production of reactive oxygen species. We found that reduced (GSH) but not oxidized (GSSG) glutathione (1–100 μM) inhibited in a dose‐dependent manner rhinovirusinduced ICAM‐1 up‐regulation and mRNA induction in primary bronchial and A549 respiratory epithelial cells. GSH but not GSSG also inhibited rhinovirus‐induced ICAM‐1 promoter activation and rhinovirus‐induced NF‐κB activation. In parallel, we found that rhinovirus infection induced a rapid increase of intracellular superoxide anion that was maximal at the time of NF‐κB activation. This oxidant generation was completely inhibited by GSH. We conclude that redox‐mediated intracellular pathways represent an important target for the therapeutic control of rhinovirusinduced diseases.

Rhinovirus infection causes steroid resistance in airway epithelium through nuclear factor κB and c-Jun N-terminal kinase activation

BACKGROUND Although inhaled glucocorticoids are the mainstays of asthma treatment, they are poorly effective at treating and preventing virus-induced asthma exacerbations. The major viruses precipitating asthma exacerbations are rhinoviruses. OBJECTIVE We sought to evaluate whether rhinovirus infection interferes with the mechanisms of action of glucocorticoids. METHODS Cultured primary human bronchial or transformed (A549) respiratory epithelial cells were infected with rhinovirus 16 (RV-16) before dexamethasone exposure. Glucocorticoid receptor (GR) α nuclear translocation, glucocorticoid response element (GRE) binding, and transactivation/transrepression functional readouts were evaluated by using immunocytochemistry, Western blotting, DNA binding assays, real-time quantitative PCR, coimmunoprecipitation, and ELISA techniques. Specific inhibitors of c-Jun N-terminal kinase (JNK) and of IκB kinase (IKK) were used to investigate the involvement of intracellular signaling pathways. RESULTS RV-16 infection impaired dexamethasone-dependent (1) inhibition of IL-1β-induced CXCL8 release, (2) induction of mitogen-activated protein kinase phosphatase 1 gene expression, and (3) binding of GR to GREs in airway epithelial cells. This was associated with impaired GRα nuclear translocation, as assessed by means of both immunochemistry (54.0% ± 6.8% vs 24.7% ± 3.8% GR-positive nuclei after 10 nmol/L dexamethasone treatment in sham- or RV-16-infected cells, respectively; P < .01) and Western blotting. RV-16 infection induced nuclear factor κB activation and GRα phosphorylation, which were prevented by inhibitors of IKK2 and JNK, respectively. In rhinovirus-infected cells the combination of JNK and IKK2 inhibitors totally restored dexamethasone suppression of CXCL8 release, induction of mitogen-activated protein kinase phosphatase 1 gene expression, and GRα nuclear translocation. CONCLUSION RV-16 infection of human airway epithelium induces glucocorticoid resistance. Inhibition of RV-16-induced JNK and nuclear factor κB activation fully reversed rhinovirus impairment of both GRα nuclear translocation and the transactivation/transrepression activities of glucocorticoids.