Changes in airway inflammation following nasal allergic challenge in patients with seasonal rhinitis.

BACKGROUND: Seasonal allergic rhinitis could predispose to the development of chronic bronchial inflammation as observed in asthma. However, direct links between nasal inflammation, bronchial inflammation and airway responsiveness in patients with seasonal allergic rhinitis and without asthma are not fully understood. The aim of this study was to analyse the changes induced by allergic nasal challenge outside the pollen season in airway responsiveness and bronchial inflammation of patients with seasonal allergic rhinitis. METHODS: Nine patients were evaluated after either grass pollens or placebo nasal challenge in a randomized cross-over double-blinded trial. Nasal parameters were recorded hourly and airway responsiveness was assessed by methacholine challenge. Cytological examinations and cytokine measurements were performed in nasal lavage and induced sputum. Eosinophil activation was investigated by eosinophil-cationic protein expression and secretion. RESULTS: Airway responsiveness was increased after allergic nasal challenge. Total eosinophils and eosinophils expressing eosinophil-cationic protein were increased in induced sputum after allergic nasal challenge. Both eosinophil number and eosinophil-cationic protein concentration in induced sputum were correlated to methacholine responsiveness. CONCLUSIONS: These results suggest that eosinophils participate to the bronchial inflammation in patients with seasonal allergic rhinitis following allergic nasal challenge outside the pollen season and might explain changes in airway responsiveness.

Involvement of caspases and of mitochondria in Fas ligation-induced eosinophil apoptosis: modulation by interleukin-5 and interferon-gamma.

In this study, we examined the relative importance of caspases and mitochondria in Fas-mediated eosinophil apoptosis. Stimulation of human peripheral blood eosinophils with an agonistic anti-human Fas monoclonal antibody, but not with control IgM, induced a time-dependent increase in their apoptosis, which was associated with a loss in mitochondrial transmembrane potential (DeltaPsi(m)) and with caspase-8 and caspase-3 activation. Interleukin (IL)-5 and interferon (IFN)-gamma, two cytokines known to prolong eosinophil survival, inhibited Fas-mediated apoptosis and caspase activation but poorly affected the decrease in DeltaPsi(m). Eosinophil incubation with bongkrekic acid, an inhibitor of the mitochondrial permeability transition pore (MPTP) opening, failed to modify Fas-mediated loss in DeltaPsi(m), caspase activation, and apoptosis. In contrast, caspase inhibitors markedly reduced eosinophil apoptosis without significantly affecting DeltaPsi(m) dissipation. We conclude that caspase-8 and caspase-3 activation, but not MPTP opening, mediate Fas-induced eosinophil apoptosis and are the main targets for the protective effect of IL-5 and IFN-gamma.

Effect of stimulation of human macrophages on intracellular survival of Mycobacterium bovis Bacillus Calmette-Guerin. Evaluation with a mycobacterial reporter strain.

The mechanisms through which immune and inflammatory responses stimulate the expression of antimycobacterial activity by human macrophages remain poorly defined. To study this question, we developed a method permitting the rapid quantification of viable mycobacteria, based on the detection of luciferase activity expressed by a Mycobacterium bovis Bacillus Calmette-Guerin (BCG) reporter strain, and used this approach to evaluate mycobacterial survival in human monocyte-derived macrophages following stimulation with cytokines and through crosslinking of costimulatory molecules expressed on the cell surface. Modest proliferation, followed by persistence of mycobacteria, was observed in unpretreated macrophages as assessed both by measurement of luciferase activity and by the evaluation of colony forming units. Of the 19 cytokines tested, only granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) were found to improve the mycobactericidal activity of monocyte-derived macrophages. In both cases, this effect was observed only when macrophages were pretreated with the cytokines prior to infection. In contrast, pretreatment of human macrophages with interferon-gamma, either alone or in combination with other mediators (including tumor necrosis factor-alpha and 1,25[OH]2-vitamin D3), did not improve mycobacterial killing. The stimulation of macrophages through several different costimulatory molecules known to participate in macrophage-lymphocyte interactions (CD4, CD40, CD45, CD86, CD95 [Fas/Apo-1]) also failed to improve mycobactericidal activity. This study shows that GM-CSF and IL-3, cytokines whose receptors are known to share a common subunit and to use common second messengers, may contribute to the stimulation of mycobactericidal activity in humans. The ability to rapidly screen the effects of different macrophage stimuli on mycobacterial survival through the detection of luciferase activity should help define additional signals required for optimal antimycobacterial responses.

Role of granulocyte-macrophage colony stimulating factor (GM-CSF) in the pathogenesis of adult pulmonary histiocytosis X.

BACKGROUND: Pulmonary histiocytosis X is a disorder characterised by the presence of destructive granulomas preferentially involving distal bronchioles, that contain numerous activated Langerhans' cells. Recent studies have shown that granulocyte-macrophage colony stimulating factor (GM-CSF), which is produced by normal bronchiolar epithelium, may play an important part in the distribution and differentiation of Langerhans' cells. The aim of this study was to evaluate the role of this factor in the pathogenesis of pulmonary histiocytosis X. METHODS: Four patients with pulmonary histiocytosis X were examined by immunohistochemical techniques for GM-CSF and CD1a surface molecules. RESULTS: In early lesions the epithelium of bronchioles affected by the disease was strongly positive for GM-CSF and infiltrated by numerous CD1a+ Langerhans' cells organised into granulomas. In contrast, the expression of GM-CSF was substantially lower in bronchioles not affected by the disease, and these bronchioles contained few Langerhans' cells. When destruction by histiocytosis X lesions was more advanced, only remnants of bronchiolar epithelium could occasionally be identified; these remained strongly reactive for GM-CSF. Langerhans' cells within granulomas also moderately expressed this cytokine. CONCLUSIONS: These results support the hypothesis that GM-CSF could be one of the factors responsible for the local accumulation of lymphostimulatory Langerhans' cells in early lesions of pulmonary histiocytosis X.

Surface phenotype of Langerhans cells and lymphocytes in granulomatous lesions from patients with pulmonary histiocytosis X.

Pulmonary histiocytosis X (HX) is a disorder characterized by the presence of granulomas in which Langerhans cells (LC) and lymphocytes are abundant. Although the pathogenesis of pulmonary HX remains unknown, an uncontrolled immune response initiated by LC, which are potent antigen-presenting cells in vitro, may play an important role. To further characterize LC and lymphocytes present in granulomas from these patients, we used immunohistochemical techniques and monoclonal antibodies to evaluate the surface phenotype and electron microscopy (EM) to seek evidence for close interactions between both cell types in these lesions. In all samples, HX granulomas contained large numbers of strongly positive CD1a cells in which typical Birbeck granules were identified by EM. The number of Birbeck granules in LC from HX granulomas was strikingly increased compared with that in LC in the bronchioles of normal subjects. Furthermore, unlike normal LC, essentially all LC in HX granulomas expressed CD4 antigens and were strongly positive for CD1c. Lymphocytes infiltrating HX granulomas were almost entirely CD3+ T cells and were mainly CD4 positive (CD4/CD8 ratio 3.7 +/- 1.3). These T lymphocytes expressed almost exclusively alpha/beta T cell receptors, and gamma/delta T cells were rarely observed (< 5% of CD3+ cells). In areas of lymphocytic infiltration, close differentiated contacts between LC and lymphocytes were observed by EM in all samples. These results demonstrate that interactions between activated LC and CD4+ T lymphocytes are prominent in early HX granulomas and support the idea that an immune response in which LC serve as accessory cells is involved in the pathogenesis of this disorder.

Evidence that granulocyte macrophage-colony-stimulating factor regulates the distribution and differentiated state of dendritic cells/Langerhans cells in human lung and lung cancers.

GM-CSF has been shown to be important for the survival and function of cells of dendritic cell/Langerhans cell (LC) lineage in vitro. Since these cells have been demonstrated to infiltrate human lung and some lung carcinomas, we hypothesized that the production of GM-CSF in the lung could be important in their recruitment and differentiation. Using both immunohistochemistry and in situ hybridization, we have shown that: (a) GM-CSF was produced by normal bronchiolar epithelium, the only site were CD1a+ LC are observed in the normal lung, whereas neither GM-CSF production nor LC were identified in normal alveolar epithelium. (b) In inflamed pulmonary tissue, hyperplastic alveolar cells produced GM-CSF, and CD1a+ LC accumulated adjacent to these cells. (c) Some, but not all, lung carcinomas produced this cytokine, and a close correlation was found between the production of GM-CSF and the number of CD1a+ LC infiltrating these tumors. Since GM-CSF was produced at all sites where CD1a+ LC are known to accumulate, but not at other locations within the lung, these data suggest that the local production of GM-CSF by certain lung cells may play an important role in determining the distribution and differentiated state of dendritic cell/LC in the human lung.