Prior Bordetella pertussis infection modulates allergen priming and the severity of airway pathology in a murine model of allergic asthma

Background It has been proposed that T helper (Th)2-driven immune deviation in early life can be countered by Th1 inducing childhood infections and that such counter-regulation can protect against allergic asthma. Objective To test whether Th1-inducing infection with Bordetella pertussis protects against allergic asthma using well-characterized murine models. Methods Groups of mice were sensitized to ovalbumin (OVA) in the presence or absence of B. pertussis, a well-characterized Th1 inducing respiratory infection. Immunological, pathological and physiological parameters were measured to assess the impact of infection on immune deviation and airway function. Results We demonstrate that OVA sensitization does not affect the development of B. pertussisspecific immune responses dominated by IgG2a and IFN-g and does not impair Th1-mediated clearance of airway infection. In contrast, B. pertussis infection at the time of sensitization modulated the response to OVA and significantly reduced total serum and OVA-specific IgE. The pattern of cytokine responses, in particular OVA-specific IL-5 responses in the spleen was also modulated. However, B. pertussis did not cause global suppression as IL-10 and IL-13 levels were enhanced in OVA-stimulated spleen cell cultures and in lavage fluid from infected co-sensitized mice. Histopathological examination revealed that B. pertussis infection prior to OVA sensitization resulted in increased inflammation of bronchiolar walls with accompanying hyperplasia and mucous metaplasia of lining epithelia. These pathological changes were accompanied by increased bronchial hyper-reactivity to methacholine exposure. Conclusion Contrary to the above premise, a Th1 response induced by a common childhood infection does not protect against bronchial hyper-reactivity, but rather exacerbates the allergic asthmatic response, despite modulation of immune mediators

gamma-delta T Cells Regulate the Early Inflammatory Response to Bordetella pertussis Infection in the Murine Respiratory Tract

The role of T cells in the regulation of pulmonary inflammation following Bordetella pertussis infection was investigated. Using a well-characterized murine aerosol challenge model, inflammatory events in mice with targeted disruption of the T-cell receptor -chain gene (TCR mice) were compared with those in wild-type animals. Early following challenge with B. pertussis, TCR mice exhibited greater pulmonary inflammation, as measured by intra-alveolar albumin leakage and lesion histomorphometry, yet had lower contemporaneous bacterial lung loads. The larger numbers of neutrophils and macrophages and the greater concentration of the neutrophil marker myeloperoxidase in bronchoalveolar lavage fluid from TCR mice at this time suggested that differences in lung injury were mediated through increased leukocyte trafficking into infected alveoli. Furthermore, flow cytometric analysis found the pattern of recruitment of natural killer (NK) and NK receptor T cells into airspaces differed between the two mouse types over the same time period. Taken together, these findings suggest a regulatory influence for T cells over the early pulmonary inflammatory response to bacterial infection. The absence of T cells also influenced the subsequent adaptive immune response to specific bacterial components, as evidenced by a shift from a Th1 to a Th2 type response against the B. pertussis virulence factor filamentous hemagglutinin in TCR mice. The findings are relevant to the study of conditions such as neonatal B. pertussis infection and acute respiratory distress syndrome where T cell dysfunction has been implicated in the inflammatory process

Présence de chimiorécepteurs sur l'aile des tsé-tsé (Diptera : Glossinidae)

Cette note signale pour la première fois l'existence de chimiorécepteurs sur les ailes des mouches tsé-tsé. Ceux-ci sont principalement localisés sur le milieu de la nervure costale. Leur morphologie est comparable à celle des chimiorécepteurs observés sur les pattes. Leur nombre ne différe pas entre les sexes comme pour les pattes, mais entre les espèces. Ceci suggère un rôle dans la perception chimique proche de l'environnement, par rapport aux chimiorécepteurs des pattes qui semblent impliqués dans le comportement sexuel. L'étude a été conduite sur six espèces ou sous-espèces de glossines. (Résumé d'auteur