Subject(s)
Neutrophil Activation/drug effects , Neutrophil Activation/genetics , Neutrophils/drug effects , Neutrophils/metabolism , Protein Kinase Inhibitors/pharmacology , Pyrazoles/pharmacology , Pyrimidines/pharmacology , Triggering Receptor Expressed on Myeloid Cells-1/genetics , Adenine/analogs & derivatives , Animals , Biomarkers , Humans , Mice , Neutrophil Activation/immunology , Neutrophils/immunology , Piperidines , Respiratory Burst/drug effects , Respiratory Burst/genetics , Respiratory Burst/immunology , Triggering Receptor Expressed on Myeloid Cells-1/metabolismABSTRACT
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
ABSTRACT
BACKGROUND: Transcutaneous immunization (TCI) is a novel vaccination strategy utilizing the skin associated lymphatic tissue to induce immune responses. TCI using a cytotoxic T lymphocyte (CTL) epitope and the Toll-like receptor 7 (TLR7) agonist imiquimod mounts strong CTL responses by activation and maturation of skin-derived dendritic cells (DCs) and their migration to lymph nodes. However, TCI based on the commercial formulation Aldara only induces transient CTL responses that needs further improvement for the induction of durable therapeutic immune responses. OBJECTIVE: Therefore we aimed to develop a novel imiquimod solid nanoemulsion (IMI-Sol) for TCI with superior vaccination properties suited to induce high quality T cell responses for enhanced protection against infections. METHODS: TCI was performed by applying a MHC class I or II restricted epitope along with IMI-Sol or Aldara (each containing 5% Imiquimod) on the shaved dorsum of C57BL/6, IL-1R, Myd88, Tlr7 or Ccr7 deficient mice. T cell responses as well as DC migration upon TCI were subsequently analyzed by flow cytometry. To determine in vivo efficacy of TCI induced immune responses, CTL responses and frequency of peptide specific T cells were evaluated on day 8 or 35 post vaccination and protection in a lymphocytic choriomeningitis virus (LCMV) infection model was assessed. RESULTS: TCI with the imiquimod formulation IMI-Sol displayed equal skin penetration of imiquimod compared to Aldara, but elicited superior CD8+ as well as CD4+ T cell responses. The induction of T-cell responses induced by IMI-Sol TCI was dependent on the TLR7/MyD88 pathway and independent of IL-1R. IMI-Sol TCI activated skin-derived DCs in skin-draining lymph nodes more efficiently compared to Aldara leading to enhanced protection in a LCMV infection model. CONCLUSION: Our data demonstrate that IMI-Sol TCI can overcome current limitations of previous imiquimod based TCI approaches opening new perspectives for transcutaneous vaccination strategies and allowing the use of this enhanced cutaneous drug-delivery system to be tailored for the improved prevention and treatment of infectious diseases and cancers.
Subject(s)
Aminoquinolines/therapeutic use , Langerhans Cells/drug effects , Lymphocytic Choriomeningitis/prevention & control , Skin Neoplasms/prevention & control , T-Lymphocytes, Cytotoxic/drug effects , Administration, Cutaneous , Animals , Cell Movement , Disease Models, Animal , Emulsions , Epitopes/immunology , Flow Cytometry , Humans , Imiquimod , Langerhans Cells/immunology , Lymphocytic Choriomeningitis/immunology , Lymphocytic Choriomeningitis/virology , Lymphocytic choriomeningitis virus/immunology , Major Histocompatibility Complex/immunology , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/metabolism , Signal Transduction/immunology , Skin/cytology , Skin/drug effects , Skin/immunology , Skin Neoplasms/immunology , T-Lymphocytes, Cytotoxic/immunology , Toll-Like Receptor 7/genetics , Toll-Like Receptor 7/metabolism , Vaccination/methodsABSTRACT
BACKGROUND: The epidermal application of the Toll Like Receptor 7 agonist imiquimod and a T-cell peptide epitope (transcutaneous immunization, TCI) mediates systemic peptide-specific cytotoxic T-cell (CTL) responses and leads to tumor protection in a prophylactic tumor setting. However, it does not accomplish memory formation or permanent defiance of tumors in a therapeutic set-up. As a distinct immunologic approach, CTLA-4 blockade augments systemic immune responses and has shown long-lasting effects in preclinical experiments as well as in clinical trials. OBJECTIVE: The study investigates the vaccination capacity of TCI in combination with the checkpoint inhibitor CTLA-4 in matters of primary response, memory formation and tumor protection and characterizes the role of regulatory T cells (Tregs). METHODS: After performing TCI with IMI-Sol (containing 5% Imiquimod) and the model epitope SIINFEKL, 6-8 week old C57BL/6 mice received anti-CTLA-4 antibody either s.c or i.p. The CTL responses and frequency of peptide specific CD8+ T-cells were then evaluated on day 8. To determine anti-tumor effects, a therapeutic tumor challenge with B16 OVA melanoma was performed. RESULTS: The combination of s.c. anti-CTLA-4 antibody and TCI leads to an enhanced systemic cytotoxic response, to memory formation and allows significantly improved survival in a tumor setting with B16 OVA melanoma. Towards the mechanism, we show that in this vaccination protocol the CTLA-4 antibody acts mainly Treg-independent. CONCLUSION: We demonstrate that the combination of TCI with IMI-Sol and anti-CTLA-4 can confer potent immune responses and tumor-protection. These results might contribute to the development of advanced vaccination approaches targeting tumors or persistent infectious diseases.