Dual-functionalized graphene oxide induces M2a and M2c macrophage polarization to orchestrate inflammation and tissue remodeling

Abstract

Functional tissue repair is often constrained by inflammation and fibrosis. Alternatively activated M2 macrophages have emerged as promising therapeutic targets for optimizing graft-to-host interactions; however, efficient induction methods are required. Presumably, the outcome of regenerative wound healing or scar formation/fibrosis might be dependent on the balance between M2a and M2c sub-phenotypes. This study utilized dual-functionalized graphene oxide (GO) as a DNA delivery agent to induce M2a and M2c macrophage polarization. Mechanistically, molecular characteristics were analyzed using RNA sequencing. We designed GO with polyethyleneimine (PEI) modification and subsequently conjugated it with polyethylene glycol (PEG)-folate (FA) to target human THP-1-derived macrophage activation. Specifically, the resulting GO-PEI-PEG-FA (GPPF) compound effectively activated CD206⁺CD209⁺M2a and CD163⁺MerTK⁺M2c phenotype polarization. The efficient delivery of IL4 or IL10 plasmid DNA using GPPF (GPPF/pIL4 or GPPF/pIL10) significantly enhanced macrophage cellular elongation and reduced MHC-II-associated antigen presentation. M2a(GPPF/pIL4) and M2c(GPPF/pIL10) were validated as negative regulators of the immune response and positive regulators of Th2 effectors. Up-regulated genes in M2a(GPPF/pIL4) even inhibited type I interferon production and restricted the innate immune response. Supplemental to the established data, M2a(GPPF/pIL4) behaved similar to IFN-responsive macrophages, restricting viral life cycles and promoting myogenesis and osteogenesis. Meanwhile, M2c(GPPF/pIL10) was characterized using IL10 signaling, anti-fibrosis, and neutrophil-mediated suppression of the LPS-bacterial response. Regarding the tissue remodeling process, the two subsets attenuated negative-regulated BMP signaling to facilitate osteoinduction and up-regulated NAMPT to establish a transient stem cell-activating niche for tissue regeneration. This study underscored the potential of functionalized GO-induced M2 sub-phenotypes as modulators in regenerative medicine.