Delivery of siRNAs to Dendritic Cells Using DEC205-Targeted Lipid Nanoparticles to Inhibit Immune Responses

Area of Science:

• Immunology
• Molecular Biology
• Nanotechnology

Background:

• Small interfering RNAs (siRNAs) offer potential for treating diseases by silencing gene expression, including for previously undruggable targets.
• Therapeutic application of siRNAs is hindered by the lack of efficient delivery systems, with current lipid nanoparticles (LNPs) primarily optimized for hepatic delivery.
• Dendritic cells (DCs) are key regulators of immune responses, making them attractive targets for immunomodulatory therapies.

Purpose of the Study:

• To develop and evaluate lipid nanoparticles (LNPs) modified for targeted delivery of siRNAs to dendritic cells (DCs).
• To assess the efficacy of siRNA-mediated gene knockdown in DCs using targeted LNPs.
• To investigate the functional consequences of DC-targeted gene knockdown on immune responses.

Main Methods:

• Lipid nanoparticles (LNPs) were engineered and coated with a single-chain variable fragment (scFv) antibody targeting murine DEC205, a marker highly expressed on specific DC subsets, creating DEC-LNPs.
• siRNAs targeting the costimulatory molecules CD40, CD80, and CD86 were encapsulated within the DEC-LNPs.
• The delivery efficiency, gene knockdown, and functional impact on immune responses (mixed lymphocyte response; MLR) were evaluated following administration of DEC-LNPs.

Main Results:

• DEC-LNPs demonstrated preferential delivery of encapsulated siRNAs to DEC205-expressing DCs following injection.
• Uptake of DEC-LNPs containing siRNAs specific for CD40, CD80, and CD86 resulted in significant gene expression knockdown.
• The observed gene knockdown was sufficient to functionally inhibit a mixed lymphocyte response (MLR), a key cellular immune assay.

Conclusions:

• siRNA delivery to DCs can be effectively achieved using antibody-targeted lipid nanoparticles (DEC-LNPs).
• Targeted gene knockdown in DCs via DEC-LNPs can profoundly modulate immune cell function.
• This approach offers a promising strategy for cell-specific gene silencing therapies, potentially applicable beyond the liver.