Systemic Gene Silencing in Primary T Lymphocytes Using Targeted Lipid Nanoparticles

TLDR

RNA interference can modulate T cell function and holds promise for treating immune disorders, yet primary T lymphocytes are notoriously difficult to transfect. This study develops a targeted lipid nanoparticle system to deliver siRNAs specifically to murine CD4⁺ T cells. The tLNPs were formulated with stability‑enhancing lipids, surface‑functionalized with anti‑CD4 antibody, and administered intravenously, resulting in efficient binding and uptake of siRNAs into CD4⁺ T lymphocytes across spleen, lymph nodes, blood, and bone marrow. Ex vivo and in vivo experiments showed that tLNPs selectively target CD4⁺ T cells, silence genes in a subset of circulating and resting cells, and that early internalization—not endosomal escape—determines efficacy, indicating that tLNPs could enable RNAi‑based therapies for leukocyte‑associated diseases.

Abstract

Modulating T cell function by down-regulating specific genes using RNA interference (RNAi) holds tremendous potential in advancing targeted therapies in many immune-related disorders including cancer, inflammation, autoimmunity, and viral infections. Hematopoietic cells, in general, and primary T lymphocytes, in particular, are notoriously hard to transfect with small interfering RNAs (siRNAs). Herein, we describe a novel strategy to specifically deliver siRNAs to murine CD4+ T cells using targeted lipid nanoparticles (tLNPs). To increase the efficacy of siRNA delivery, these tLNPs have been formulated with several lipids designed to improve the stability and efficacy of siRNA delivery. The tLNPs were surface-functionalized with anti-CD4 monoclonal antibody to permit delivery of the siRNAs specifically to CD4+ T lymphocytes. Ex vivo, tLNPs demonstrated specificity by targeting only primary CD4+ T lymphocytes and no other cell types. Systemic intravenous administration of these particles led to efficient binding and uptake into CD4+ T lymphocytes in several anatomical sites including the spleen, inguinal lymph nodes, blood, and the bone marrow. Silencing by tLNPs occurs in a subset of circulating and resting CD4+ T lymphocytes. Interestingly, we show that tLNP internalization and not endosome escape is a fundamental event that takes place as early as 1 h after systemic administration and determines tLNPs' efficacy. Taken together, these results suggest that tLNPs may open new avenues for the manipulation of T cell functionality and may help to establish RNAi as a therapeutic modality in leukocyte-associated diseases.