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Delivery of macromolecules into cytosol using liposomes containing hemolysin from Listeria monocytogenes
1Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Abstract:
The cytosolic space of cells is an important but relatively inaccessible target for the delivery of therapeutic macromolecules. Here we describe the efficient delivery of macromolecules into the cytosolic space of macrophages from liposomes that contain listeriolysin O (LLO), the hemolytic protein of Listeria monocytogenes that normally mediates bacterial passage from phagosomes into cytosol. LLO was purified and encapsulated inside pH-sensitive liposomes, along with other molecules to be delivered. When internalized by bone marrow-derived macrophages, these liposomes rapidly released encapsulated fluorescent dye, first into endosomes and then into the cytosol, without measurably harming the cells. Furthermore, these liposomes efficiently delivered encapsulated ovalbumin to the cytosolic pathway of antigen processing and presentation, as measured by the major histocompatibility complex (MHC) class I-restricted presentation of peptides derived from ovalbumin. Delivery was significantly better than that obtained by other currently available liposome formulations. LLO-containing liposomes should therefore provide an efficient vehicle for delivery of antigens or therapeutic molecules in vivo.
Insights
Researchers developed novel liposomes using listeriolysin O (LLO) to efficiently deliver macromolecules into the cell cytosol. This breakthrough offers a new method for targeted drug delivery and antigen presentation in macrophages.
Area of Science:
- Cell Biology
- Immunology
- Drug Delivery Systems
Background:
- The cytosol is a challenging cellular compartment for therapeutic macromolecule delivery.
- Existing liposome formulations have limitations in achieving efficient cytosolic entry.
Purpose of the Study:
- To develop and evaluate liposomes containing listeriolysin O (LLO) for efficient macromolecule delivery into the cytosol of macrophages.
- To assess the safety and efficacy of LLO-containing liposomes for antigen delivery and presentation.
Main Methods:
- Purification and encapsulation of LLO within pH-sensitive liposomes.
- Internalization of LLO-liposomes by bone marrow-derived macrophages.
- Measurement of fluorescent dye release into endosomes and cytosol.
- Assessment of ovalbumin delivery via MHC class I-restricted antigen presentation.
Main Results:
- LLO-containing liposomes efficiently delivered macromolecules into the macrophage cytosol.
- Delivery occurred without significant cellular toxicity.
- Enhanced cytosolic delivery and MHC class I presentation of ovalbumin compared to other liposome formulations.
Conclusions:
- LLO-functionalized liposomes represent a promising and efficient vehicle for cytosolic delivery of therapeutic molecules and antigens.
- This approach overcomes previous barriers in targeting the cellular cytosol for therapeutic interventions.