RESUMO
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.
Assuntos
Toxinas Bacterianas/genética , Biofilmes/crescimento & desenvolvimento , Epiderme/microbiologia , Regulação Bacteriana da Expressão Gênica , Proteínas Hemolisinas/genética , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Fatores de Virulência/genética , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Toxinas Bacterianas/biossíntese , Toxinas Bacterianas/metabolismo , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Hemolisinas/biossíntese , Proteínas Hemolisinas/metabolismo , Humanos , Queratinócitos/microbiologia , Leucocidinas/biossíntese , Leucocidinas/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Modelos Biológicos , Poliestirenos/química , Cultura Primária de Células , Regiões Promotoras Genéticas , Fatores de Virulência/biossínteseRESUMO
Ageing is due to the accumulation of damage, which arises because of evolved limitations in mechanisms for maintenance and repair. Accumulated damage may cause genomic instability, which in organisms with renewable tissues may result in cancer. To keep cancer at bay, two different tumour suppression mechanisms evolved: caretakers and gatekeepers. Caretakers protect the genome against mutations, while gatekeepers induce cell death or cell cycle arrest of potentially tumourigenic cells. It has been hypothesised that decreased activity of a caretaker may reduce life span, by increasing cancer risk, while the effects of increased activity of a gatekeeper on cancer risk and life span may be antagonistically pleiotropic. Apoptosis and senescence will promote early-life survival by curtailing the development of cancer, but may eventually limit longevity. This article reviews the evidence for this hypothesis. We conclude that several different findings indeed hint at an important role for gatekeeper mediated processes in ageing and its related pathologies. The relative contribution of apoptosis and senescence in specific age-related pathologies remains to be established.