Regulation of the innate immune system by fragmented heparin-conjugated lipids on lipid bilayered membranes in vitro

J Mater Chem B. 2023 Nov 29;11(46):11121-11134. doi: 10.1039/d3tb01721d.

Abstract

Surface modification with heparin is a powerful biomaterial coating strategy that protects against innate immunity activation since heparin is a part of the proteoglycan heparan sulfate on cell surfaces in the body. We studied the heparinization of cellular and material surfaces via lipid conjugation to a heparin-binding peptide. In the present study, we synthesized fragmented heparin (fHep)-conjugated phospholipids and studied their regulation of the innate immune system on a lipid bilayered surface using liposomes. Liposomes have versatile applications, such as drug-delivery systems, due to their ability to carry a wide range of molecules. Owing to their morphological similarity to cell membranes, they can also be used to mimic a simple cell-membrane to study protein-lipid interactions. We investigated the interaction of complement-regulators, factor H and C4b-binding protein (C4BP), as well as the coagulation inhibitor antithrombin (AT), with fHep-lipids on the liposomal surface. Herein, we studied the ability of fHep-lipids to recruit factor H, C4BP, and AT using a quartz crystal microbalance with dissipation monitoring. With dynamic light scattering, we demonstrated that liposomes could be modified with fHep-lipids and were stable up to 60 days at 4 °C. Using a capillary western blot-based method (Wes), we showed that fHep-liposomes could recruit factor H in a model system using purified proteins and assist in the degradation of the active complement protein C3b to iC3b. Furthermore, we found that fHep-liposomes could recruit factor H and AT from human plasma. Therefore, the use of fHep-lipids could be a potential coating for liposomes and cell surfaces to regulate the immune system on the lipid surface.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anticoagulants
  • Antithrombins / pharmacology
  • Complement Factor H
  • Heparin*
  • Humans
  • Immune System / metabolism
  • Lipid Bilayers
  • Liposomes* / chemistry

Substances

  • Heparin
  • Liposomes
  • Complement Factor H
  • Lipid Bilayers
  • Antithrombins
  • Anticoagulants