Immunomodulatory Therapy of Inflammatory Liver Disease Using Selectin-Binding Glycopolymers

Abstract

Immunotherapies have the potential to significantly advance treatment of inflammatory disease and cancer, which are in large part driven by immune cells. Selectins control the first step in immune cell adhesion and extravasation, thereby guiding leukocyte trafficking to tissue lesions. We analyzed four different highly specific selectin-binding glycopolymers, based on linear poly(2-hydroxypropyl)-methacrylamide (PHPMA) polymers. These glycopolymers contain either the tetrasaccharide sialyl-Lewis (SLe) or the individual carbohydrates fucose, galactose, and sialic acids mimicking the complex SLe binding motive. The glycopolymers strongly bind to primary human macrophages, without activating them, and also to primary human blood leukocytes, but poorly to fibroblasts and endothelial cells in vitro. After intravenous injection in mice, all glycopolymers accumulated in the liver without causing hepatotoxicity. The glycosylated binder most potently targeted resident hepatic macrophages (Kupffer cells) and protected mice from acute toxic liver injury in the two different experimental models, carbon tetrachloride (CCl) or Concanavalin A (ConA)-based hepatitis. Its sulfated counterpart, on the other hand, induced a decrease in infiltrating and resident macrophages, increased T helper cells, and aggravated immune-mediated liver injury. We demonstrate that, in the context of selectin-binding glycopolymers, minor modifications strongly impact leukocyte influx and macrophage activation, thereby ameliorating or aggravating liver inflammation depending on the underlying immunopathology. The nonsulfated random glycopolymer is a promising candidate for the treatment of inflammatory disease. The modulation of hepatic immune cells by selectin-binding glycopolymers might breach the immunosuppressive hepatic microenvironment and could improve efficacy of immunotherapies for inflammatory disease and cancer.

Carbohydrate supramolecular chemistry: beyond the multivalent effect

“…Underestimating the latter can totally offset the enthalpic benefit of cooperativity due to the entropic penalty associated with linker flexibility. 58,59 Recently, Zentel and coworkers 60 and Tacke and coworkers 61 conveyed compelling evidence of the potential of mimicking the selectin recognition properties of the sialyl Lewis x (SLe x ) tetrasaccharide (NeuNAc-a(2-3)-Gal-b(1-4)-[Fuc-a(1-3)]-GlcNAc) by the carbohydrate module approach for biomedical applications. Selectins are a family of cell adhesion molecules with an extracellular lectin domain that bind to fucosylated and sialylated glycoproteins and play a key role in the innate immune response.…”

“…60 Additionally, the latter heteroglycopolymer strongly bound to resident liver macrophages in vivo (mice) and meaningfully inhibited toxic liver injury and reduced the injury in a model of immune-mediated hepatitis. 61 Heteromultivalent prototypes having the crucial glycotopes prearranged in segregated domains are expected to be better suited to simultaneously target lectins differing in their sugar selectivities. This concept has been probed by the groups of Roy and coworkers and Renaudet and coworkers with Janus 65 Multiconjugates combining sugar head groups optimized for the Pseudomonas aeruginosa (P. aeruginosa) lectins LecA and LecB (namely Gal and Fuc) or LecA and concanavalin A (ConA), a model mannose (Man)-binding lectin used throughout many fundamental studies, were synthesized and evaluated.…”

“…Structure of the sialyl Lewis x (SLe x ) tetrasaccharide and schematic representation of the heteroglycopolymers conceived by Zentel and coworkers60 and Tacke and coworkers61 to emulate the SLe x selectin binding capabilities.…”

Nanomaterial Manipulation of Immune Microenvironment in the Diseased Liver

“…Conversed to current understanding of AuNPs as bioinert materials, Carvalho et al demonstrated spherical neutral AuNPs that selectively accumulated in liver KCs were capable to downregulate the activity of KCs through decreasing the secretion of proinflammatory cytokines including IL‐1β and TNF‐α, fibrogenic factors such as TGF‐β and fibroblast growth factor (FGF), and ROS mediated by AKT/PI3K and mitogen‐activated protein kinase (MAPK) signaling pathways, leading to attenuated steatosis and reduced necrosis as well as inflammatory infiltrates (e.g., neutrophils) in a rat alcohol‐methamphetamine‐induced liver injury model. Bartneck et al used an activated ester approach for the synthesis of linear poly(2‐hydroxypropyl)‐methacrylamide (PHPMA) glycopolymers with four different selectin (transmembrane glycoprotein molecules expressed on the surface of activated leukocytes to mediate their adhesion to vascular for further trans‐endothelial migration) binders: Sialy Lewis X tetrasaccharide (SLe X ) (P1), SLe X with O‐sulfated tyramine (P2), randomly linked carbohydrates with or without O‐sulfated tyramine (P3 and P4) ( Figure ). After confirming the strongest interactions of the selectin‐binding glycopolymers (SBG) with monocytes and macrophages but low binding to fibroblasts and endothelial cells in vitro, they further demonstrated the potent KC‐targeting capacity of SBG without causing hepatoxicity in vivo.…”

“…D) Therapeutic effects of selectin‐binding glycopolymers on CCL4 induced liver injury. All panels reproduced with permission . Copyright 2017, American Chemical Society.…”