ABSTRACT
BACKGROUND: Timothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. OBJECTIVE: The aim of this study was to characterize changes in TG-specific T cell responses as a function of seasonality. METHODS: Peripheral blood mononuclear cells (PBMCs) obtained from allergic individuals and non-allergic controls, either during the pollen season or out of season, were stimulated with either TG extract or a pool of previously identified immunodominant antigenic regions. RESULTS: PBMCs from allergic subjects exhibit higher IL-5 and IL-10 responses in season than when collected out of season. In the case of non-allergic subjects, as expected we observed lower IL-5 responses and robust production of IFN-γ compared to allergic individuals. Strikingly, non-allergic donors exhibited an opposing pattern, with decreased immune reactivity in season. The broad down-regulation in non-allergic donors indicates that healthy individuals are not oblivious to allergen exposure, but rather react with an active modulation of responses following the antigenic stimulus provided during the pollen season. Transcriptomic analysis of allergen-specific T cells defined genes modulated in concomitance with the allergen exposure and inhibition of responses in non-allergic donors. CONCLUSION AND CLINICAL RELEVANCE: Magnitude and functionality of T helper cell responses differ substantially in season vs. out of season in allergic and non-allergic subjects. The results indicate the specific and opposing modulation of immune responses following the antigenic stimulation during the pollen season. This seasonal modulation reflects the enactment of specific molecular programmes associated with health and allergic disease.
Subject(s)
Allergens/immunology , Immunomodulation , Phenotype , Phleum/immunology , Pollen/immunology , Rhinitis, Allergic, Seasonal/diagnosis , Rhinitis, Allergic, Seasonal/immunology , Case-Control Studies , Cytokines/metabolism , Female , Gene Expression Profiling , Gene Expression Regulation , HLA Antigens/genetics , HLA Antigens/immunology , Humans , Immunologic Memory , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/metabolism , Lymphocyte Activation , Lymphocyte Count , Male , RNA, Messenger/genetics , Rhinitis, Allergic, Seasonal/genetics , Rhinitis, Allergic, Seasonal/metabolism , Seasons , T-Cell Antigen Receptor Specificity , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolism , TranscriptomeABSTRACT
The bronchial epithelium is an important physical barrier that regulates physiological processes including leukocyte trafficking. The aim of the present study was to elucidate the mechanisms whereby the bronchial epithelium, stimulated by epidermal growth factor (EGF) as part of a response to acute or chronic injury, could activate and chemoattract human neutrophils. Subconfluent human bronchial epithelial (16HBE) cells were stimulated with EGF to mimic the in vivo events after injury. The effect of the resulting EGF-conditioned media (CM) was compared with that of basal-CM with respect to neutrophil activation and chemotaxis. Such findings were then confirmed using primary bronchial epithelial cells (PBECs) from healthy volunteers. EGF-CM from 16HBE cells caused increased expression of CD11b/CD66b and CD62L loss on neutrophils when compared with basal-CM. EGF-CM contained significant neutrophil chemotactic activity involving granulocyte-macrophage colony-stimulating factor and interleukin-8 that was potentiated by leukotriene B(4). This was dependent on neutrophil phosphatidylinositol-3-kinase activation and Akt phosphorylation, with partial regulation by phospholipase D, but not mammalian target of rapamycin. Consistent with these observations, EGF-CM derived from PBECs displayed increased chemotactic activity. The present results suggest that the enhanced chemotactic activity of the epidermal growth factor-conditioned epithelium can enhance neutrophil-mediated immunity during acute injury, while during continued injury and repair, as in chronic asthma, this could contribute to persistent neutrophilic inflammation.
Subject(s)
Bronchi/immunology , Chemotaxis, Leukocyte/immunology , Epidermal Growth Factor/immunology , Inflammation/immunology , Neutrophils/immunology , Bronchi/cytology , Cell Line , Culture Media, Conditioned , Epidermal Growth Factor/physiology , Epithelial Cells/immunology , Humans , Respiratory Distress Syndrome/immunology , Signal TransductionABSTRACT
INTRODUCTION: The technique of induced expectoration generates sputum by the inhalation of hypertonic saline. On account of its non-invasive character, its simplicity, its relative harmlessness, its cost effectiveness and its reproducibility this technique, that appeared in the early 1990's, has rapidly established itself as the technique of choice in the investigation of bronchial inflammation in asthma. STATE OF THE ART: We present the results of our studies that have contributed to the validation of the technique at the methodological level and to the exploitation of the cellular contents as much as the fluid phase of the expectorations in characterising bronchial inflammation in asthmatics. Our results confirm an infiltration of the airways of asthmatics with eosinophils that appears to be proportional to the severity of the illness. We evaluate the effect of inhaled steroids and of theophylline on sputum eosinophilia and bronchial reactivity and discuss the role of eosinophils on bronchial hyperreactivity. Finally we discuss the use of induced expectoration in clinical practice in asthma. PERSPECTIVES: The analysis of induced sputum could well become a valuable tool in the clinical evaluation and monitoring of asthma in the same way as symptoms and abnormalities of lung function. CONCLUSIONS: Induced expectoration has certainly contributed to the understanding of the cellular and molecular mechanisms of asthma as well as the role of bronchial inflammation in the clinical manifestations of the disease.
