Conclusion
We found that the ST239-III clone was able to infect, at 3h p.i., 50%
of MG-63 human osteoblasts and these rates stably persisted at 24h p.i.;
during the infection peri-od it exerted an extremely significative
cytotoxic activity against osteoblasts, due to the over- expression ofhla and psm A, as demonstrated by a remarkable decrease in
the cellular metabolic status. The increase of hla and psmA has as a
consequence the increased of expression of the genes involved in
adhesion (bbp ), probably due to the release and re-entry of
bacteria inside MG-63 at 24h p.i. Our results lead us to conclude that
the ST239 clone is more prone to persistent infections.
On the contrary, ST228-I was found to be less able to internalize
(30%), with respect to the control strain and ST239-III, after 3h p.i.
and to persist (20%) at 24h p.i., and this lower in-vasiveness was also
correlated with the non-cytotoxic activity inside osteoblasts. This is
probably due to the presence of the pls gene into SCCmec I, that
is involved in the failure to adhere to the cell surface. This clone is
not able to activate a sufficient cellular reaction, and succumbs inside
the MG-63 cells.
Author contributions: Dafne Bongiorno : Conceptualization
(equal); Investigation (equal); Methodology (equal); Project
administration (lead); Validation (equal); Visualization (equal);
Writing - original draft preparation (equal); Writing – review &
editing (equal). Nicolò Musso : Conceptualization (equal);
Investigation (equal); Methodology (equal); Formal analysis (equal);
Project administration (supporting); Validation (equal); Visualization
(equal); Writing - original draft preparation (equal). Giuseppe
Caruso: Investigation (equal); Methodology (equal); Formal analysis
(equal); Validation (equal); Visualization (equal); Lorenzo
Mattia Lazzaro : Investigation (supporting); Formal analysis
(supporting); Filippo Caraci : Resources (equal);Stefania Stefani: Founding acquisition (equal);Resources (equal); Supervision (equal); Writing – review & editing
(equal). Floriana Campanile : Founding acquisition
(equal); Conceptualization (equal); Resources (equal);
Methodology (supporting); Supervision (equal); Writing – review &
editing (equal).
Acknowledgments: Some of the results of this study were
presented at the 29th ECCMID (O0927) and at the 44th Italian Society of
Microbiology (SIM) congress (P127). We would like to thank the BRIT
laboratory at the University of Catania (Italy) for valuable technical
assistance and use of their laboratories. We also wish to thank the
Scientific Bureau of the University of Catania for language support. The
manuscript was partially supported by: a research grant project number
PRIN2017SFBFER from the Ministry of Research (MIUR) Italy; a research
grant from a private company; a research grant entitled “Identification
of cancer driver genes for novel diagnostics and therapeutic strategies
– Piano per la ricerca 2016-2018 – Linea di intervento 2 – University
of Catania, Dept. of Biomedical and Biotechnological Sciences”.
Conflicts of Interest : The authors declare that the research
was conducted in the absence of any commercial or financial
relationships that could be construed as a potential conflict of
interest.
Ethics statement : None required.