Abstract

Sepsis is a serious disease associated with macrophage polarization and endothelial permeability. The DAG/PKC/ROS pathway is crucial for sepsis development, macrophage polarization and endothelial permeability. As CD4 + T cell-derived exosomes can modulate the DAG/PKC/ROS pathway, we aimed to investigate the role and mechanism of exosomes from DGKK-knockdown CD4 + T cells in sepsis. RAW264.7 cells were exposed to lipopolysaccharide and interferon-gamma (L/I) to promote M1 polarization and then co-cultured with exosomes. The macrophages were co-cultured with lipopolysaccharide-stimulated PMVECs. Additionally, phorbol 12-myristate 13-acetate (PMA), a PKC agonist, was used to treat macrophages. Furthermore, sepsis mouse models were established via cecal ligation and puncture (CLP) surgery. In vitro, lipopolysaccharide increased DGKK expression in CD4⁺T cells and CD4⁺T cell-derived exosomes. L/I-induced M1 macrophage polarization and DAG/PKC/ROS pathway activation were amplified by lipopolysaccharide-stimulated CD4⁺T cell exosomes. However, exosomes from DGKK-knockdown CD4⁺T cells counteracted these effects. Furthermore, treatment with these exosomes improved PMVEC viability, decreased apoptosis, alleviated inflammation, and decreased permeability. In vivo, CLP-induced inflammation, organ (lung/liver/kidney) injury, M1 macrophage polarization, DAG/PKC/ROS pathway activation, and lung permeability were further aggravated by LPS-stimulated CD4⁺T cell exosomes. However, exosomes from DGKK-knockdown CD4⁺T cells counteracted these deteriorations, while macrophage depletion abolished the protective effects of DGKK-knockdown CD4⁺T cell-derived exosomes in sepsis. Importantly, the effects of exosomes from DGKK-knockdown CD4⁺T cells on M1 macrophage polarization and endothelial permeability were reversed by PMA. In conclusion, exosomes from DGKK-knockdown CD4 + T cells mitigated sepsis by suppressing the DAG/PKC/ROS pathway-mediated M1 macrophage polarization and reducing endot