Antigen Presentation and Proteome Study of Exosomes Secreted by Co-Culture of Macrophages and Talaromyces marneffei.

Abstract

It is known that intracellular pathogens interact and react with the cellular immune system through exosomes produced by macrophages. This study aimed to determine whether co-culture of macrophages and Talaromyces marneffei induces exosomes and leads to immune responses. T. marneffei was incubated to collect conidia, co-cultured with human macrophages, which then induced exosomes. In cellular experiments, after extraction and purification, the exosomes were then observed by electron microscopy and detected by flow cytometry and mass spectrometry. In animal experiments, flow cytometry and enzyme-linked immunosorbent assay were used to examine whether exosomes were antigenpresenting. The results showed that purified exosomes produced a pro-inflammatory response and stimulated production of TNF-α in non-fungal-treated macrophages. Protein mass spectrometry analysis of exosomes also indicated their potential ability to activate the internal immune response system and the pro-inflammatory response. Translation and ribosomes were the most abundant GO terms in proteins, and the most relevant KEGG pathway was the biosynthesis of secondary metabolites. Furthermore, in vivo experiments revealed that exosomes induced activation of lymphocytes and increased expression of TNF-α and IL-12 in the lung, mediastinum, and spleen area. In conclusion, exosomes can be released by co-culture of T. marneffei and macrophages, having antigen-presenting functions, promoting macrophage inflammation, and initiating adaptive immune responses. These processes are inextricably linked to the translation of secondary metabolites, ribosomes and biosynthesis.