Staphylococcus aureus ST228 and ST239 as models for expression studies of diverse markers during osteoblast infection and persistence. Issue 2 (1st May 2021)

• Record Type: Journal Article
• Authors: Bongiorno, Dafne; Musso, Nicolò; Caruso, Giuseppe; Lazzaro, Lorenzo Mattia; Caraci, Filippo; Stefani, Stefania; Campanile, Floriana
• Is Part Of: MicrobiologyOpen. Volume 10:Issue 2(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-01
• Subjects: crosstalk mechanism -- MRSA -- osteoblast -- ST228 -- ST239 -- virulence toxin; Microbiology -- Periodicals; 579
• DOI: 10.1002/mbo3.1178
• Languages: English
• ISSNs: 2045-8827

Abstract

Abstract: The ability of S. aureus to infect bone and osteoblasts is correlated with its incredible virulence armamentarium that can mediate the invasion/internalization process, cytotoxicity, membrane damage, and intracellular persistence. We comparatively analyzed the interaction, persistence, and modulation of expression of selected genes and cell viability in an ex vivo model using human MG‐63 osteoblasts of two previously studied and well‐characterized S. aureus clinical strains belonging to the ST239‐SCC mec III‐t037 and ST228‐SCC mec I‐t041 clones at 3 h and 24 h post‐infection (p.i). S. aureus ATCC12598 ST30‐t076 was used as a control strain. Using imaging flow cytometry (IFC), we found that these strains invaded and persisted in MG‐63 osteoblasts to different extents. The invasion was evaluated at 3 h p.i and persistence at 24 h p.i., in particular: ATCC12598 internalized in 70% and persisted in 50% of MG‐63 cells; ST239‐SCC mec III internalized in 50% and persisted in 45% of MG‐63 cells; and ST228‐SCC mec I internalized in 30% and persisted in 20% of MG‐63 cells. During the infection period, ST239‐III exerted significant cytotoxic activity resulting from overexpression of hla and psm A and increased expression of the genes involved in adhesion, probably due to the release and re‐entry of bacteria inside MG‐63 cells at 24 h p.i. The lower invasiveness of ST228‐I was also associated with non‐cytotoxic activity inside osteoblasts. This clone was unable to activate sufficient cellular reaction and succumbed inside MG‐63 cells. Our findings support the idea of considering new strategies, based on a translational approach—eukaryotic host–pathogen interaction (EHPI)—and to be applied on a large scale, to predict S. aureus /osteoblast interaction and treat bone infections. Such strategies rely on the study of the genetic and biochemical basis of both pathogen and host. Abstract : Using imaging flow cytometry analysis, we found that strains differently invaded osteoblasts after 3 h and 24 h: ST239‐SCCmecIII in 50% and 45% and ST228‐SCCmecI in 30% and 20%, respectively. ST239‐III exerted a significant cytotoxic activity due to the overexpression of hla and psmA and the increased expression of the genes involved in adhesion, probably due to the release and re‐entry of bacteria inside MG‐63 at 24 h p.i. The lower invasiveness of ST228‐I was also correlated with the non‐cytotoxic activity inside osteoblasts.