The Proteome of Plasma Extracellular Vesicles in Latent and Active Tuberculosis Reveals Phase-Specific Composition...

Tuberculosis (TB) is an infectious disease that affects millions of people worldwide. Extracellular vesicles (EVs) are mediators of intercellular communication that participate in the immunopathogenesis of TB. Here, we characterized plasma EVs from healthy individuals and from individuals with latent (LTB) or active TB (ATB). We found increased total protein concentrations in EVs from LTB and ATB individuals compared to healthy controls, without significant differences in EV concentrations, but reduced exosome abundance in LTB. Proteomic and bioinformatic analysis showed that LTB EVs were enriched in proteins associated with the regulation of inflammation, tissue remodeling, and lipid metabolism, including TGFβ and apolipoproteins (APO) A1 and E. In contrast, ATB EVs were enriched in mycobacterial antigens and host proteins associated with acute inflammation, including serum amyloid A1 and A2 (SAA1/A2) and the calgranulin complex proteins S100A8 and S100A9. These host proteins were central and/or cohesive nodes in the protein-protein interaction networks of these EVs. Dot blot analysis confirmed the increased levels of these EV proteins in a second group of individuals with LTB or ATB. The EV levels of mycobacterial antigens correlated positively with the EV levels of SAA1/A2 and S100A8/A9, but negatively with their levels of TGFβ and APOA1. Principal component analysis and hierarchical clustering suggested that the simultaneous analysis of mycobacterial antigens and these EV proteins could discriminate between healthy, LTB, and ATB individuals. Our findings confirm that plasma EVs provide insights into the host immunometabolic response to TB and may be a source of clinically useful biomarkers.