Molecular design of phosphatidylserine-inspired polymers for efficient anti-inflammatory therapy via enhanced interaction with Tim-4

Abstract This study investigated the interaction between phosphatidylserine (PS)-inspired polymers, T-cell immunoglobulin and mucin-like domain-containing protein 4 (Tim-4) by systematically varying the monomer structure and copolymer composition. A series of alkyl-substituted PS-inspired monomers was synthesized using a modified phosphoramidite method, and well-defined homopolymers and 2-hydroxyethyl methacrylate (HEMA)-containing copolymers were prepared via reversible addition–fragmentation chain-transfer polymerization. Structural analyses using 1 H nuclear magnetic resonance and gel permeation chromatography confirmed the successful synthesis with controlled molecular weights. Biolayer interferometry was used to quantify Tim-4 binding, revealing a nonmonotonic effect of alkyl substitution, whereas the incorporation of HEMA consistently enhanced Tim-4 binding in a composition-dependent manner. Biological evaluation using RAW-Blue macrophages revealed that the homopolymers did not significantly affect interleukin-6 (IL-6) secretion, whereas the copolymers selectively suppressed IL-6 production. Notably, the copolymer containing 50 mol% PS units exhibited the strongest IL-6 suppression, and the HEMA-containing copolymers exhibited anti-inflammatory activity even at lower PS concentrations than the homopolymers did. These results demonstrate that the copolymer composition critically influences receptor interactions and immune modulation. This study highlights the potential of PS-inspired copolymers as biomaterials that mimic apoptotic cell signals and exert efficient anti-inflammatory effects through an optimized molecular design.