Polymer-based nanoparticles loaded with a TLR7 ligand to target the lymph node for immunostimulation

Area of Science:

• Nanotechnology
• Immunology
• Oncology

Background:

• Small-molecule agonists for Toll-like receptors (TLR) 7 and 8 show promise in skin cancer immunotherapy.
• Systemic administration of these agents is limited by dose-limiting toxicities.

Purpose of the Study:

• To develop a polymer-based nanodelivery system for resiquimod, a TLR7 ligand.
• To target resiquimod to lymph nodes for enhanced immunotherapy and reduced systemic inflammation.

Main Methods:

• Resiquimod was encapsulated in methoxypoly(ethylene glycol)-b-poly(DL-lactic acid) (mPEG-PLA) and mixed poly(DL-lactic-co-glycolic acid) (PLGA)/mPEG-PLA nanoparticles.
• Nanoparticle uptake by dendritic cells and macrophages was assessed.
• In vivo studies in mice evaluated lymph node targeting after subcutaneous injection.

Main Results:

• Successful encapsulation of resiquimod in mPEG-PLA and PLGA/mPEG-PLA nanoparticles was demonstrated.
• Nanoparticles were primarily taken up by dendritic cells and macrophages, activating them.
• In vivo, nanoparticles were detected in dendritic cells and macrophages within draining lymph nodes, confirming targeting.

Conclusions:

• Polymer-based nanoparticles facilitate lymph node targeting of resiquimod.
• This nanodelivery system shows potential for systemic cancer immunotherapy by focusing immunostimulatory activity and preventing generalized inflammation.