Bacillus Calmette-Guerin (BCG) is reported to suppress Th2 response and asthmatic reaction. Dendritic cells (DCs), the major antigen-presenting cells, infections with BCG are known to result in inducing various cytokines. Thus, DCs are likely to play a role in the effects of BCG on asthma. This study aims at investigating that cytokine milieu secreted by BCG-treated DCs directly enhances allergen-specific Th1 response and/or suppresses Th2 response in allergic asthma. DCs and CD3+ T cells were generated from Dermatophagoides farinae-sensitive asthmatics. DCs were cultured with and without BCG and subjected to flow cytometric analysis. IL-12 and IL-10 were determined from the culture supernatants. Some DCs were cocultured with T cells in the presence of D. farinae extracts after adding the culture supernatants from BCG-treated DCs, and IL-5 and IFN-gamma were determined. BCG-treated DCs enhanced significantly the expressions of CD80, CD86, and CD40, and the productions of IL-12 and IL-10. Addition of culture supernatants from BCG-treated DCs up-regulated production of IFN-gamma by T cells stimulated by DCs and D. farinae extracts (p<0.05), but did not down-regulate production of IL-5 (p>0.05). The cytokine milieu secreted by BCG-treated DCs directly enhanced allergen-specific Th1 response, although did not suppress Th2 response.
Antigens, Dermatophagoides/*immunology ; Asthma/*immunology ; Cells, Cultured ; Coculture Techniques ; Culture Media ; Cytokines/*immunology/secretion ; Dendritic Cells/cytology/*immunology/secretion ; Humans ; Hypersensitivity/immunology ; Interferon Type II/immunology/secretion ; Interleukin-10/immunology/secretion ; Interleukin-12/immunology/secretion ; Interleukin-5/immunology/secretion ; Lymphocyte Activation/immunology ; Mycobacterium bovis/*immunology ; Research Support, Non-U.S. Gov't ; Th2 Cells/cytology/immunology/secretion ; Up-Regulation/immunology

OBJECTIVETo investigate the effect of respiratory syncytial virus (RSV) infection on the production of thymic stromal lymphopoietin (TSLP) and Th1/Th2 balance in asthmatic mice.

METHODSThirty-two female BALB/c mice were randomly divided into 4 groups, namely the PBS group, ovalbumin (OVA) group, RSV group and OVA/RSV group. The mice were sensitized by OVA and then stimulated with nebulized OVA, and RSV was inoculated into the nasal cavity of the mice. BUXCO noninvasive lung function detection was performed to examine the airway response to metacholine, and enzyme-linked immunosorbent assay (ELISA) was used to detect the serum levels of IL-4, IL-5, IL-13, and IFN-gamma in the mice. The cells in the bronchoalveolar lavage fluid (BALF) were counted and classified, and the supernatants of the BALF were used for the detection of TSLP. Histopathological changes in the lung tissues of the mice were examined using HE staining, and immunohistochemistry using anti-mouse TSLP antibody was performed to examine TSLP expressions in the airway epithelial cells.

RESULTSRSV infection promoted the production of TSLP in the asthmatic mice, and the concentration of TSLP in OVA/RSV group (2.13-/+0.05 ng/ml) was significantly higher than that in the other groups (P<0.01). RSV infection increased the serum levels of IL-4, IL-5, IL-13, and IFN-gamma in the mice. The total BALF cells, eosinophils, lymphocytes and neutrophils in OVA/RSV group were significantly higher than those in the other groups; noninvasive lung function examination showed higher Penh value in OVA/RSV group (318.66-/+50.87) than in the other groups when the inhaled metacholine increased to 6.25 mg/ml (P<0.01). More obvious and extensive airway inflammatory cell infiltration in OVA/RSV group were observed, and immunohistochemical staining also showed higher expression of TSLP in the airway epithelial cells of OVA/RSV group.

CONCLUSIONSRSV infection promotes the production of TSLP in the airway epithelial cells and increases the level of Th2 cytokines in asthmatic mice. Concurrent RSV infection can exacerbate Th2 inflammatory reaction in asthmatic mice.

Animals ; Bronchoalveolar Lavage Fluid ; Cytokines ; biosynthesis ; secretion ; Female ; Immunohistochemistry ; Inflammation ; immunology ; virology ; Interferon-gamma ; blood ; Interleukins ; blood ; Lung ; immunology ; metabolism ; virology ; Mice ; Mice, Inbred BALB C ; Respiratory Syncytial Virus Infections ; blood ; immunology ; metabolism ; Th2 Cells ; cytology ; immunology ; virology