Proteomic profiling of LPS-induced macrophage derived exosomes indicates their involvement in acute liver injury.

Exosomes are typically involved in cellular communication and signaling. Macrophages play a key role in lipopolysaccharide (LPS)-induced sepsis. However, the molecular comparison of exosomes derived from LPS-induced macrophage has not been well analyzed. The macrophage-exosomes are validated and the protein composition of those exosomes are investigated by isobaric tags for relative and absolute quantification (iTRAQ) mass spectrometry. A total of 5056 proteins are identified in macrophage-exosomes. We discovered 341 increased proteins and 363 reduced proteins in LPS-treated macrophage-exosomes compared with control exosomes. In addition, gene ontology analysis demonstrates that macrophage-exosomes proteins are mostly linked to cell, organelle, extracellular region, and membrane. The bioinformatics analysis also indicates that these proteins are mainly involved in cellular process, single-organism process, metabolic process, and biological regulation. Among these 341 upregulated proteins, Kyoto Encyclopedia of Genes and Genomes analysis reveals that 22 proteins are involved in the NOD-like receptor signaling pathway. Finally, hepatocytes can uptake macrophage-exosomes and subsequently NLRP3 inflammasome is activated in vitro and in vivo. These data emphasize the fundamental importance of macrophage-exosomes in sepsis-induced liver injury. Therefore, the iTRAQ proteomic strategy brings new insights into macrophage-derived exosomes. It may improve our understanding of macrophage-exosomes' functions and their possible use as therapeutic targets for sepsis.