Transcutaneous immunization studies in mice using diphtheria toxoid-loaded vesicle formulations and a microneedle array.
OBJECTIVE
To determine the immunogenicity of diphtheria toxoid (DT) formulated in two types of vesicles following transcutaneous immunization (TCI) of mice onto microneedle array-treated skin.


METHODS
DT-containing cationic liposomes or anionic surfactant-based vesicles were prepared by extrusion and sonication. The physicochemical properties were characterized in terms of size, ζ-potential, vesicle elasticity and antigen association. TCI was performed by applying formulations onto intact or microneedle array-pretreated mice skin, using cholera toxin as an adjuvant. Subcutaneous and intradermal immunizations were as control. Immune responses were evaluated by IgG and neutralizing antibody titers, and the immune-stimulatory properties were assessed using cultured dendritic cells.


RESULTS
Stable DT-containing cationic liposomes (∼150 nm) and anionic vesicles (∼100 nm) were obtained. Incorporation of Span 80 increased liposome elasticity. About 90% and 77% DT was associated with liposomes and vesicles, respectively. TCI of all formulations resulted in substantial antibody titers only if microneedle pretreatment was applied. Co-administration of cholera toxin further augmented the immune responses of TCI. However, vesicle formulations didn't enhance the immunogenicity on either intact or microneedle-treated skin and showed low stimulatory activity on dendritic cells.


CONCLUSIONS
Microneedle pretreatment and cholera toxin, but not antigen association to vesicles, enhances the immunogenicity of topically applied DT.
Division of Drug Delivery Technology Leiden/Amsterdam Center for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
Zhi
Z
Ding
Suzanne M
SM
Bal
Stefan
S
Romeijn
Gideon F A
GF
Kersten
Wim
W
Jiskoot
Joke A
JA
Bouwstra
D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood / Q000276:immunology; D002478:Cells, Cultured; D002626:Chemistry, Pharmaceutical; D003713:Dendritic Cells / Q000276:immunology; D004168:Diphtheria Toxoid / Q000008:administration & dosage* / Q000276:immunology; D004337:Drug Carriers / Q000737:chemistry; D004548:Elasticity; D005260:Female; D006801:Humans; D007114:Immunization / Q000295:instrumentation / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007271:Injections, Intradermal; D007279:Injections, Subcutaneous; D008081:Liposomes; D051379:Mice; D008807:Mice, Inbred BALB C; D008845:Microinjections / Q000295:instrumentation / Q000379:methods*; D009339:Needles
D057134:Antibodies, Neutralizing; D004168:Diphtheria Toxoid; D004337:Drug Carriers; D007074:Immunoglobulin G; D008081:Liposomes