Bridging Small Molecules to Modified Bacterial Microparticles Using a Disulphide Linkage: MIS416 as a Cargo Delivery System

• Published in: PloS one 2015-12, Vol.10 (12), p.e0145403-e0145403
• Main Authors: Mainini, Francesco, Larsen, David S, Webster, Gill A, Young, Sarah L, Eccles, Michael R
• Format: Article
• Language: English
• Subjects: Acids; Acne; Animals; Antigen presentation; Antigen Presentation - drug effects; Antigen-presenting cells; Antigens; Bacteria; Biocompatibility; Biodegradation; Brain cancer; Cancer Vaccines - chemistry; Cancer Vaccines - pharmacology; Cargo; Cell activation; Cell proliferation; Cell Proliferation - drug effects; Cell walls; Cells, Cultured; Chemical bonds; Conjugates; Conjugation; Cytoplasm; Cytotoxicity; Degradation; Dendritic cells; Dendritic Cells - drug effects; Dendritic Cells - immunology; Development and progression; Disulfides - chemistry; Drug Carriers - chemistry; Drug Carriers - pharmacology; Experiments; Genetic aspects; Immune response; Lymphocytes T; Lysosomes; Major histocompatibility complex; Mice; Microparticles; Nucleic acids; Ovalbumin; Ovalbumin - chemistry; Ovalbumin - pharmacology; Pathology; Peptide Fragments - chemistry; Peptide Fragments - pharmacology; Peptides; Physiological aspects; Spleen - cytology; Studies; T cell receptors; T cells; Toxicity; Vaccines, Conjugate - chemistry; Vaccines, Conjugate - pharmacology; Wilkins, Maurice
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0145403

MIS416 is an intact minimal cell wall skeleton derived from Proprionibacterium acnes that is phagocytosed by antigen presenting cells, including dendritic cells (DCs). This property allows MIS416 to be exploited as a vehicle for the delivery of peptide antigens or other molecules (for example, nucleic acids) to DCs. We previously showed that covalent (non-cleavable) conjugation of OVA, a model antigen derived from ovalbumin, to MIS416 enhanced immune responses in DCs in vivo, compared to unconjugated MIS416 and OVA. Intracellular trafficking promotes the lysosomal degradation of MIS416, leading to the destruction of MIS416 plus the associated cargos conjugated to MIS416. However, lysosomal degradation of cargo may not be desired for some MIS416 conjugates. Here we have investigated whether a cleavable linkage could facilitate release of the cargo in the cytoplasm of DCs to avoid lysosomal degradation. DCs were treated in vitro with disulfide-containing conjugates, and as hypothesised faster release of SIINFEKL peptide in the cytoplasm of DCs was observed with the inclusion of a disulfide bond between MIS416 and cargo. The inclusion of a cleavable disulfide bond in the conjugates did not significantly alter the amount of SIINFEKL antigens presented on MHC I molecules on DCs as compared with conjugates without a disulfide bond. However, the conjugates containing disulfide-linkages performed either slightly better (p