Solid nanoemulsion as antigen and immunopotentiator carrier for transcutaneous immunization

Area of Science:

• Dermatology
• Immunology
• Pharmaceutical Sciences

Background:

• Imiquimod, a toll-like receptor 7 (TLR7) agonist, is used for topical treatment of skin lesions.
• Transcutaneous immunization (TCI) offers a needle-free method for antigen delivery.
• Solid nanoemulsions (SNs) are explored for enhanced dermal drug administration.

Purpose of the Study:

• To investigate the efficacy of imiquimod-loaded SNs for transcutaneous immunization.
• To evaluate the impact of different oil components on SN formulation performance.
• To compare the in vivo immune response of SNs with conventional topical formulations.

Main Methods:

• Development of solid nanoemulsions (SNs) containing imiquimod and peptide antigen SIINFEKL.
• High-pressure homogenization and freeze-drying for SN formulation.
• In vitro drug permeation studies using Franz diffusion cells and murine skin.
• In vivo assessment of cytotoxic T-cell response in C57BL/6 mice.

Main Results:

• SN formulations reduced imiquimod permeation compared to Aldara® cream.
• All tested SNs induced a specific T-cell lysis in vivo.
• A squalene/tocopherol-stabilized SN showed significantly higher performance than Aldara®.
• MCT-based SNs demonstrated comparable in vivo effects to Aldara®.

Conclusions:

• Anhydrous, highly dispersed SNs with submicron imiquimod particles are promising for TCI.
• The choice of oil component critically influences SN performance, independent of in vitro permeation.
• SN formulations offer a viable needle-free approach for effective dermal immunization.