Dna Carrier with Ova or Immune-Modulators to Asthmatic Mice

Bronchial asthma is a chronic inflammatory disorder of the airways. It has been well established that cytokines produced by Th2 type cells are responsible for asthmatic pathology. Despite intensive effort designed to develop pharmacological agents to block inflammatory mediators, therapeutic strategy with long-term benefits has not been available. Direct DNA injection of allergen genes has been proposed to enhance specific Th1 response and showed some encouraging results in sensitized animals. Alternatively, genes carried by attenuated Salmonella bacteria have been tested as vaccine systems in the treatment of infectious diseases and tumors. Higher antigen-specific Th1 activity was also observed. With the established murine asthmatic model using chicken ovalbumin (OVA) as allergen, we have investigated the possible oral vaccine and therapeutic strategy with the use of attenuated Salmonella as the DNA carrier system. The administration of attenuated Salmonella suppressed the allergic symptoms in OVA-sensitized mice. In order to enhance the allergen-specific immune responses, a transcriptional regulatory element from woodchuck hepatitis virus (WPRE) was constructed into the vector to promote the expression of OVA. Although vector with WPRE increased OVA gene expression and stimulated high level of IFN-？HH？H？H production from OVA-stimulated splenocytes, the transformed SL7207 could not effectively suppress OVA-specific hypersensitive responses. Alternatively, OVA protein is expressed with prokaryotic vector and then the attenuated Salmonella can delivery the allergen orally into the sensitized mice. Two prokaryotic vectors (pGEX-3X and pkk223-3) were tested and no significant therapeutic effect was achieved. We then created a new vector with the combination of these 2 vectors. The new vector expressed higher amount of OVA in Salmonella with IPTG induction. We will test whether it can modulate hypersensitive responses in the following year. Other immune-modulatory genes will also be constructed and the effect on asthmatic animals will be examined.

Project ID:PG9503-0602
External Project ID:NHRI-EX95-9110SC