Agonists of Toll-like receptors (TLRs) are potent activators of the innate immune system and hold promise as vaccine adjuvant and for anticancer immunotherapy. Unfortunately, in soluble form they readily enter systemic circulation and cause systemic inflammatory toxicity. Here we demonstrate that by covalent ligation of a smallmolecule imidazoquinoline-based TLR7/8 agonist to 50-nm-sized degradable polymeric nanogels the potency of the agonist to activate TLR7/8 in in vitro cultured dendritic cells is largely retained. Importantly, imidazoquinoline-ligated nanogels focused the in vivo immune activation on the draining lymph nodes while dramatically reducing systemic inflammation. Mechanistic studies revealed a prevalent passive diffusion of the nanogels to the draining lymph node. Moreover, immunization studies in mice have shown that relative to soluble TLR7/8 agonist, imidazoquinoline-ligated nanogels induce superior antibody and T-cell responses against a tuberculosis antigen. This approach opens possibilities to enhance the therapeutic benefit of small-molecule TLR agonist for a variety of applications.nanotechnology | Toll-like receptor | dendritic cells | lymph node | vaccine A ctivation of the innate immune system crucially depends on the recognition of evolutionary conserved microbe-associated molecular patterns by host pattern recognition receptors (PRRs). Triggering of PRRs not only elicits a direct antimicrobial and inflammatory cascade but also activates the necessary antigen-presenting cells to subsequently prime antigen-specific T-and B-cell immune responses (1). Agonists of Toll-like receptors (TLRs) are among the most potent activators of the innate immune response identified to date and, thus, are under intensive investigation as adjuvants for vaccination (2) or as agents for anticancer immunotherapy (3). Especially promising in this context are agonists of the endosomal TLR7 and TLR8, which typically recognize singlestranded RNAs generated during viral infection (4) but can also be activated by synthetic small-molecule agonists (5). Molecular adjuvants (6, 7) that are agonists of TLR7/8 indeed activate a broad spectrum of antigen-presenting cells, both in mice (only TLR7) and humans, and typically induce high levels of type I IFN and IL-12, the most vital cytokines to drive the Th1 and cytotoxic T-cell responses required to combat intracellular infections and cancer (7,8).Due to their pharmacokinetic profile, most molecular adjuvants rapidly diffuse after administration and evoke systemic inflammatory responses that cause dose-limiting toxicity (9, 10). In the context of intratumoral administration, these dose-limiting toxicities prevent these compounds from reaching the necessary intratumoral concentration to yield real therapeutic benefit. In the context of vaccination, the rapid diffusion of molecular adjuvants dramatically lowers the ability of antigen and TLR agonist to reach the same antigen-presenting cells in the draining lymph node (DLN), which results in suboptimal immunity to the del...

We report on the design of glycosylated nanogels via core-cross-linking of amphiphilic non-watersoluble block copolymers composed of an acetylated glycosylated block and a pentafluorophenyl (PFP) activated ester block prepared by RAFT polymerization. Self-assembly, pH-sensitive corecross-linking and removal of remaining PFP esters and protecting groups is achieved in one-pot yielding fully hydrated sub-100 nm nanogels. Using cell subsets that exhibit high and low expression of the mannose receptor under conditions that suppress active endocytosis, we show that mannosylated but not galactosylated nanogels can efficiently target the mannose receptor (MR) that is expressed on the cell surface of primary dendritic cells (DCs). These nanogels hold promise for immunological applications involving DCs and macrophage subsets.

Living cells are anchored with magnetic microcapsules that allow in vitro manipulation via a magnetic field.

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