title: Surface assembly of poly(I:C) on PEGylated microspheres to shield from adverse interactions with fibroblasts.
abstract: By expressing an array of pattern recognition receptors (PRRs), fibroblasts play an important role in stimulating and modulating the response of the innate immune system. The TLR3 ligand polyriboinosinic acid-polyribocytidylic acid, poly(I:C), a mimic of viral dsRNA, is a vaccine adjuvant candidate to activate professional antigen presenting cells (APCs). However, owing to its ligation with extracellular TLR3 on fibroblasts, subcutaneously administered poly(I:C) bears danger towards autoimmunity. It is thus in the interest of its clinical safety to deliver poly(I:C) in such a way that its activation of professional APCs is as efficacious as possible, whereas its interference with non-immune cells such as fibroblasts is controlled or even avoided. Complementary to our previous work with monocyte-derived dendritic cells (MoDCs), here we sought to control the delivery of poly(I:C) surface-assembled on microspheres to human foreskin fibroblasts (HFFs). Negatively charged polystyrene (PS) microspheres were equipped with a poly(ethylene glycol) (PEG) corona through electrostatically driven coatings with a series of polycationic poly(L-lysine)-graft-poly(ethylene glycol) copolymers, PLL-g-PEG, of varying grafting ratios g from 2.2 up to 22.7. Stable surface assembly of poly(I:C) was achieved by incubation of polymer-coated microspheres with aqueous poly(I:C) solutions. Notably, recognition of both surface-assembled and free poly(I:C) by extracellular TLR3 on HFFs halted their phagocytic activity. Ligation of surface-assembled poly(I:C) with extracellular TLR3 on HFFs could be controlled by tuning the grafting ratio g and thus the chain density of the PEG corona. When assembled on PLL-5.7-PEG-coated microspheres, poly(I:C) was blocked from triggering class I MHC molecule expression on HFFs. Secretion of interleukin (IL)-6 by HFFs after exposure to surface-assembled poly(I:C) was distinctly lower as compared to free poly(I:C). Overall, surface assembly of poly(I:C) may have potential to contribute to the clinical safety of this vaccine adjuvant candidate.
authors.affiliation: Institute of Pharmaceutical Sciences, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: Annina M
authors.initials: AM
authors.lastname: Hafner
authors.forename: Daniel
authors.initials: D
authors.lastname: Burschowsky
authors.forename: Blaise
authors.initials: B
authors.lastname: Corthésy
authors.forename: Marcus
authors.initials: M
authors.lastname: Textor
authors.forename: Hans P
authors.initials: HP
authors.lastname: Merkle
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology; D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects; D004337:Drug Carriers / Q000737:chemistry*; D005347:Fibroblasts / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D052816:Foreskin / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006367:HeLa Cells; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008863:Microspheres; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology; D011070:Poly I-C / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry*; D011107:Polylysine / Q000031:analogs & derivatives* / Q000737:chemistry; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis
chemical_list: D000276:Adjuvants, Immunologic; D004337:Drug Carriers; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; C443714:polylysine-graft-(poly(ethylene glycol)); D011107:Polylysine; D011092:Polyethylene Glycols; D011070:Poly I-C