DNA immunotherapy with polyphosphoester microspheres and nanospheres

The immune response to DNA vaccines can be modified and enhanced by the surrounding cytokine milieu so delivery of the appropriate cytokines by biodegradable polymeric controlled-release systems may be beneficial. The physical size of the administered DNA-containing systems is critical for uptake by the appropriate tissues and for processing by cells. A polyphosphoester polymer was chosen due to its attractive degradation and physicochemical properties. Parameters that affect the size of controlled-release biodegradable microspheres and nanospheres were examined, and spheres in defined size ranges were produced.; These spheres were administered into mice by two routes: the muscle and the bladder. Intramuscular administration of bolus plasmid LacZ (pLacZ) elicited an antibody response, which was no different than when recombinant IFN-γ protein (rIFN-γ) was co-injected as bolus or encapsulated in microspheres. Additionally, microsphere-encapsulated LacZ co-injected with bolus rIFN-γ did not produce an antibody response. In contrast, when DNA was either coencapsulated or coinjected with encapsulated rIFN-γ, the antibody response was significantly enhanced, especially the T_H2 response. These findings may lead to the use of cytokines as specific adjuvants in a much different manner than they are presently used, since the effects of a particular cytokine may be based upon the kinetics of administration.; Bladder administration of polyphosphoester nanospheres containing DNA resulted in bladder uptake and trafficking to the lymphatics and transport to the lymph node interior, which was not seen with larger sizes of the same spheres (microspheres). Furthermore, nanospheres of a different polymer, polystyrene, did not enter the lymph node. For polyphosphoester nanospheres, gene expression was noted in the lymph nodes, and immune responses such as an antibody response and spleen enlargement were observed. These results illustrate the interesting potential of the bladder delivery route in immunization and the startling dependence of tissue trafficking on particulate composition.; In summary, coadministration of antigen-encoding DNA with microencapsulated cytokine protein (rIFN-γ) or nanoencapsulated cytokine genes (pGM-CSF) via the intramuscular and bladder routes of delivery, respectively, were found to enhance the immune responses to the DNA vaccine. Thus, the encapsulation of genes and cytokine proteins into biodegradable spheres may customize the immune responses to gene-based immunotherapies.