ABSTRACT
BACKGROUND: Use of the reverse targeting drug delivery system (RT-DDS) is a new targeting strategy based on the specific delivery of drugs to immune cells in antigen-sensitized animals by using antigen-modified liposomes, and it is expected to be a curative treatment for allergic diseases. PURPOSE: Herein, we prepared ovalbumin (OVA)-modified liposomes encapsulating the immunosuppressive drug FK506 (OVA-LipFK) and aimed to demonstrate the delivery selectivity of the liposomes to splenic B cells, and its antiallergic effect in an OVA-sensitized allergic model mouse. METHODS: Fluorescently labeled OVA-LipFK was intravenously injected into OVA-sensitized mice, and the intrasplenic localization of liposomes was observed. The antiallergic effect of OVA-LipFK in OVA-sensitized mice was examined by measuring the blood levels of OVA-specific IgE and IgG antibodies. RESULTS AND DISCUSSION: OVA-LipFK was co-localized to not only B cells but also germinal centers, in the spleen of OVA-sensitized mice. However, there was no accumulation of unmodified liposomes encapsulating FK506 (LipFK) in the splenic B-cell area. In a therapeutic study, OVA-LipFK significantly suppressed the production of both OVA-specific IgE and IgG antibodies in OVA-sensitized mice after the animals had been boosted with OVA, whereas LipFK showed little antiallergic effect. CONCLUSIONS: The present study suggested that the introduction of RT-DDS for use with immunosuppressive drugs could be useful for the treatment of allergic diseases.
Subject(s)
B-Lymphocytes/drug effects , Hypersensitivity/immunology , Liposomes/chemistry , Ovalbumin/immunology , Spleen/cytology , Tacrolimus/chemistry , Animals , Immunosuppressive Agents , Liposomes/pharmacokinetics , Mice , Ovalbumin/chemistry , Tacrolimus/pharmacokinetics , Tissue DistributionABSTRACT
A specific antigen-sensitized animal has antigen-specific immune cells that recognize the antigen. Therefore, an antigen-modified drug carrier would be recognized by the immune cells. When such a carrier encapsulates certain drugs, these drugs should be specifically delivered to the immune cells. To examine this strategy, ovalbumin (OVA) was used as model antigen, and mice were presensitized with 100 µg of OVA with Alum. For preparing OVA-modified liposomes (OVA-lipo), OVA was incubated with DSPE-PEG-NHS and resulting DSPE-PEG-OVA was inserted into liposomes. OVA-specific IgG was produced 6-fold higher by intravenous injection of OVA-lipo thrice (10 µg as OVA in each injection) in OVA-sensitized mice, than that by the injection of control liposomes, suggesting that OVA-lipo was recognized by the antigen-specific immune cells. Moreover, intra-splenic accumulation of OVA-lipo was observed in OVA-sensitized mice, but not in naive mice. To achieve the delivery of a drug to specific immune cells, OVA-lipo encapsulated low dose of doxorubicin (DOX) as a model drug (20 µg DOX/mouse, Ca. 1 mg/kg) was injected in the sensitized mice. The injection of OVA-lipo encapsulating DOX suppressed the production of IgE against OVA, suggesting that the specific delivery of the drug to immune cells responsible for OVA recognition was achieved and that these immune cells were removed by the drug treatment. This strategy would be useful for the fundamental treatment of allergy by the use of immunosuppressing agents.
