Oral Presentation Asia-Pacific Vaccine and Immunotherapy Congress 2026

Subcutaneous, lymph node-directed, liposome antigen-specific immunotherapy enables immune regulation and disease suppression in autoimmune arthritis (#52)

Shehzahdi Moonshi 1 , Thais Aragao Horoiwa 1 , Bijun Zeng 1 , Rebecca Lane 2 , Nick Fletcher 2 , Ellen Gillespie 1 , Alexander Martyn 2 , Ning Liu 1 , Mai Thao T Tran 3 , Naisarg Pujara 1 , Rhia Stone 2 , Swati Patel 1 , Jamie Rossjohn 3 4 , Matt Trau 2 , Meghna Talekar 1 , Kristofer Thurecht 2 , Hanno Nel 1 , Ranjeny Thomas 1
  1. Frazer Institute, University of Queensland, Brisbane, QLD, Australia
  2. Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia
  3. Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
  4. Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom

Objective

Achieving sustained drug-free remission remains a major unmet goal in rheumatoid arthritis (RA), as current disease-modifying anti-rheumatic drugs (DMARDs) suppress inflammation but do not restore immune tolerance, leading to relapse after treatment withdrawal. Antigen-specific immunotherapy (ASI) offers a strategy to re-establish tolerance by directing disease-relevant CD4⁺ T-cell epitopes to antigen-presenting cells (APCs) in an immunomodulatory context. Liposomal ASI platforms co-encapsulating self-antigen and NF-κB inhibitors have shown potential to regulate autoimmune responses; however, stable in vivo delivery of multiple active components to lymph nodes without direct lymph node administration remains a significant translational challenge. Here we optimized ASI liposomes for stability and lymph node uptake by APCs and evaluated in-vivo biodistribution, immune regulation, and effects in experimental arthritis.

Methods

Liposomes encapsulating an autoantigenic peptide and the NF-κB inhibitor calcitriol were produced by microfluidic mixing. Initial in-vitro studies identified rapid peptide release and liposome destabilisation following plasma exposure, necessitating systematic optimisation of lipid composition and formulation conditions. Liposomes were optimized for in-vitro stability using novel protease and size exclusion chromatography assays to resolve intact liposomes from unencapsulated components. For biodistribution studies, 89zirconium-labeled peptide antigens and 3H-calcitriol liposomes were imaged with PET-CT and analyzed ex vivo. Fluorescently labelled liposomes were tracked with in vivo imaging, flow cytometry and confocal microscopy. Arthritis severity was evaluated in the proteoglycan-induced arthritis (PGIA) model in the context of weekly conventional treatment with methotrexate and short-course dexamethasone.

Results

Optimized semi-synthetic POPC/POPG/PEG liposomes formed particles with a mean hydrodynamic diameter of 119.18 nm, low polydispersity (PDI 0.132), a negative surface charge (−40.3 mV), and high peptide encapsulation efficiency (>80%), with <15% variation in physicochemical parameters over 28 days. Lipid, peptide and calcitriol were initially high at the injection site, with prolonged peptide retention in draining lymph nodes but not other organs, while free peptide cleared rapidly via renal pathways. ASI liposomes taken up by draining lymph node myeloid dendritic cells and germinal centre B cells of primed mice suppressed expression of MHC class II and costimulatory molecules in an antigen-specific manner. In PGIA, conventional drug treatment and ASI but not empty liposomes significantly induced regulatory T cells, suppressed proinflammatory T cells, improved arthritis scores and prevented the flare in disease activity associated with withdrawal of conventional drugs.

Conclusions

Optimized semi-synthetic ASI liposomes overcome stability and delivery barriers to modulate lymph node antigen presentation, resulting in antigen-specific immune regulation and disease control even after standard drug withdrawal.