ABSTRACT
Vesicle-based medicines hold great promise for therapy development but essential knowledge on the bio-distribution and longevity of vesicles after administration is lacking. We generated vesicles from the membranes of human mesenchymal stromal cells (MSC) and we demonstrated earlier that these so-called membrane particles (MP) mediate immunomodulatory and regenerative responses in target cells. In the present study we examined the bio-distribution and longevity of MP after intravenous administration in mice. While most vesicle tracking methods are based on imaging techniques, which require labeling of vesicles and can only detect dense accumulations of vesicles, we used proteomics analysis to detect the presence of MP-derived proteins in multiple organs and tissues. MP proteins were mainly present in plasma and leukocytes at 1 h after injection, indicating that MP - in contrast to whole MSC - do not accumulate in the lungs upon first passage but remain in circulation. After 24 h, MP proteins were still present in plasma but were most abundant in the liver. RNA sequencing of livers demonstrated that MP impact liver function and in particular induce metabolic pathways. These data provide a clear view of the bio-distribution and longevity of MP, which is likely extrapolatable to other types of vesicles, and demonstrate that MP circulate for up to 24 h and may be a tool for targeting the liver.
Subject(s)
Extracellular Vesicles , Mesenchymal Stem Cells , Animals , Extracellular Vesicles/metabolism , Humans , Immunomodulation , Liver , Mesenchymal Stem Cells/metabolism , MiceABSTRACT
BACKGROUND & AIM: The ability of Staphylococcus aureus to successfully colonize (a)biotic surfaces may be explained by biofilm formation and the actions of virulence factors. The aim of the present study was to establish the presence of 52 proteins, including virulence factors such as alpha-toxin, during biofilm formation of five different (methicillin resistant) S. aureus strains on Leiden human epidermal models (LEMs) and polystyrene surfaces (PS) using a competitive Luminex-based assay. RESULTS: All five S. aureus strains formed biofilms on PS, whereas only three out of five strains formed biofilms on LEMs. Out of the 52 tested proteins, six functionally diverse proteins (ClfB, glucosaminidase, IsdA, IsaA, SACOL0688 and nuclease) were detected in biofilms of all strains on both PS and LEMs. At the same time, four toxins (alpha-toxin, gamma-hemolysin B and leukocidins D and E), two immune modulators (formyl peptide receptor-like inhibitory protein and Staphylococcal superantigen-like protein 1), and two other proteins (lipase and LytM) were detectable in biofilms by all five S. aureus strains on LEMs, but not on PS. In contrast, fibronectin-binding protein B (FnbpB) was detectable in biofilms by all S. aureus biofilms on PS, but not on LEMs. These data were largely confirmed by the results from proteomic and transcriptomic analyses and in case of alpha-toxin additionally by GFP-reporter technology. CONCLUSION: Functionally diverse virulence factors of (methicillin-resistant) S. aureus are present during biofilm formation on LEMs and PS. These results could aid in identifying novel targets for future treatment strategies against biofilm-associated infections.
Subject(s)
Bacterial Toxins/genetics , Biofilms/growth & development , Epidermis/microbiology , Gene Expression Regulation, Bacterial , Hemolysin Proteins/genetics , Methicillin-Resistant Staphylococcus aureus/genetics , Methicillin-Resistant Staphylococcus aureus/pathogenicity , Virulence Factors/genetics , Bacterial Proteins/biosynthesis , Bacterial Proteins/genetics , Bacterial Toxins/biosynthesis , Bacterial Toxins/metabolism , Genes, Reporter , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Hemolysin Proteins/biosynthesis , Hemolysin Proteins/metabolism , Humans , Keratinocytes/microbiology , Leukocidins/biosynthesis , Leukocidins/genetics , Methicillin-Resistant Staphylococcus aureus/growth & development , Models, Biological , Polystyrenes/chemistry , Primary Cell Culture , Promoter Regions, Genetic , Virulence Factors/biosynthesisABSTRACT
The ultimate step in the blood coagulation cascade is the formation of fibrin. Several proteins are known to bind to fibrin and may thereby change clot properties or clot function. Our previous studies identified carboxypeptidase N (CPN) as a novel plasma clot component. CPN cleaves C-terminal lysine and arginine residues from several proteins. The activity of CPN is increased upon its proteolysis by several proteases. The aim of this study is to investigate the presence of CPN in a plasma clot in more detail. Plasma clots were formed by adding thrombin, CaCl(2) and aprotinin to citrated plasma. Unbound proteins were washed away and non-covalently bound proteins were extracted and analyzed with 2D gel electrophoresis and mass spectrometry. The identification of CPN as a fibrin clot-bound protein was verified using Western blotting. Clot-bound CPN consisted of the same molecular forms as CPN in plasma and its content was approximately 30 ng/ml plasma clot. Using surface plasmon resonance we showed that CPN can bind to fibrinogen as well as to fibrin. In conclusion, CPN binds to fibrinogen and is present in a fibrin clot prepared from plasma. Because CPN binds to a fibrin clot, there could be a possible role for CPN as a fibrinolysis inhibitor.
