Motoyoshi Suzuki

Dendritic cells are associated with augmentation of antigen sensitization by influenza A virus infection in mice

To study the mechanisms responsible for enhanced sensitization of inhaled antigen in respiratory viral infections, we examined the contribution of dendritic cells (DC) and T lymphocytes to the development of inhalation sensitization during infection with influenza A virus in mice. BALB / c mice were sensitized by inhalation of ovalbumin (OA) from 3 to 7 days after the inoculation with influenza A virus, and were challenged with OA 3 weeks later. Airway responsiveness and serum OA‐specific IgE were increased. The numbers of eosinophils and CD4+ and CD8+ T cells in bronchoalveolar lavage fluid were also increased. These changes were not observed in animals only sensitized with OA or only inoculated with the virus. In animals only inoculated with the virus, DC were immunohistochemically detected on the bronchial epithelium on days 2 – 5. With OA inhalation after virus inoculation, DC with high expression of MHC class II were retained for 5 weeks. These results show that influenza virus infection induces the migration of DC to the bronchial epithelium, and that simultaneous inhalation of antigen causes the loading of antigen‐peptide / class II molecule complex on DC. Thus, the migration of DC in viral infection may play some role in the augmentation of antigen sensitization.

Immune Response Induced by Airway Sensitization after Influenza A Virus Infection Depends on Timing of Antigen Exposure in Mice

ABSTRACT To study which phase of viral infection promotes antigen sensitization via the airway and which type of antigen-presenting cells contributes to antigen sensitization, BALB/c mice were sensitized by inhalation of ovalbumin (OA) during the acute phase or the recovery phase of influenza A virus infection, and then 3 weeks later animals were challenged with OA. The numbers of eosinophils and lymphocytes, the amounts of interleukin-4 (IL-4) and IL-5 in the bronchoalveolar lavage fluid, and the serum levels of OA-specific immunoglobulin G1 (IgG1) and IgE increased in mice sensitized during the acute phase (acute phase group), while a high level of gamma interferon production was detected in those sensitized during the recovery phase (recovery phase group). In the acute phase group, both major histocompatibility complex class II molecules and CD11c were strongly stained on the bronchial epithelium; in the recovery phase group, however, neither molecule was detected. OA-capturing dendritic cells (DCs) migrated to the regional lymph nodes, and a small number of OA-capturing macrophages were also observed in the lymph nodes of the acute phase group. In the recovery group, however, no OA-capturing DCs were detected in either the lungs or the lymph nodes, while OA-capturing macrophages were observed in the lymph nodes. These results indicate that the timing of antigen sensitization after viral infection determines the type of immune response.

Effects of β2-agonists on the contractility of fatigued canine diaphragm in vivo

We examined the effects of four beta 2-agonists, clenbuterol, metaproterenol, procaterol, and albuterol, on the contractility of fatigued canine diaphragm. Diaphragmatic contractility was assessed from changes in transdiaphragmatic pressure (Pdi) generated by supramaximal electrical stimulation of the phrenic nerve. Diaphragmatic fatigue was developed by applying an inspiratory resistive load to spontaneously breathing dogs for 30-50 min. Four doses of each beta 2-agonist were intravenously administered to dogs when the decreased Pdi became stable. Clenbuterol increased Pdi at doses of 10 and 20 micrograms/kg (P < 0.05). Metaproterenol improved Pdi of the fatigued diaphragm at low stimulation frequencies in a dose-dependent manner (P < 0.05). Procaterol increased Pdi at a low dose but decreased Pdi at higher doses, possibly due to a marked decrease in systemic blood pressure. Albuterol did not change Pdi at any dose. These results suggest that both clenbuterol and metaproterenol have a positive inotropic effect on fatigued canine diaphragm, while procaterol has a negative effect at high doses. Albuterol showed no inotropic effect.

Adenoviral vector–mediated gene transfer of IL-13Rα2 chain followed by IL-13 cytotoxin treatment offers potent targeted therapy for cytotoxin-resistant cancers

Previous studies demonstrated that IL‐13Rα2 chain–overexpressing cancer cells were highly sensitive to IL‐13 cytotoxin (IL13‐PE38QQR) and could be targeted by cytotoxin treatment. However, the majority of human tumors do not express high levels of IL‐13Rα2 chain. To expand the IL‐13 cytotoxin–mediated cancer targeting therapy, we combined cytotoxin treatment with gene transfer of IL‐13Rα2 chain. We constructed a recombinant adenoviral vector carrying the human IL‐13Rα2 gene (Ad‐IL‐13Rα2), which expresses high levels of IL‐13Rα2 chain on infected cells. Human cancer cell lines A549 and HOS, which originally show no IL‐13Rα2 expression and little sensitivity to IL‐13 cytotoxin, were effectively converted to become sensitive to this cytotoxin after Ad‐IL‐13Rα2 infection. The CC50 of IL‐13 cytotoxin for Ad‐IL‐13Rα2‐infected A549 cells was <10 ng/ml, whereas the CC50 for uninfected or control vector‐infected cells was >500 ng/ml. We also examined the antitumor activity of IL‐13 cytotoxin in an established xenograft model of cytotoxin‐resistant human lung tumor. Only a single i.t. injection of Ad‐IL‐13Rα2 markedly enhanced the sensitivity of established tumors to IL‐13 cytotoxin treatment; furthermore, this antitumor effect was significantly sustained for more than 1 month after the last treatment with IL‐13 cytotoxin. Taken together, these results suggest the combination of adenoviral vector–mediated IL‐13Rα2 gene transfer and IL‐13 cytotoxin administration can be an effective targeting approach for several types of IL‐13 cytotoxin–resistant cancers which show no or little expression of IL‐13Rα2 chain.