Project description:Squalene makes up 12 % of human skin surface lipids, however little is known about its affects on the host skin microbiome. Here we tested the effect of squalene on genetic regulation of staphylococci, showing that it profoundly affects expression virulence or colonisation determinants, and of iron uptake systems.
Project description:Staphylococci are major pathogens in humans and animals and emerging antibiotic-resistant strains have further increased the importance of this health issue. The existence of a genetic basis of host response to bacterial infections has been widely documented but the underlying mechanisms and genes are still largely unknown. Previously, two divergent lines of sheep selected on their milk somatic cell count called high and low SCS lines, have been showed to be respectively more and less susceptible to intra mammary infections (IMI). Transcriptional profiling of milk somatic cells (MSC) of high and low SCS sheep infected successively by S. epidermidis and S. aureus was performed to provide enhanced knowledge about the genetic basis of differential host response to IMI with Staphylococci. Gene expression in MSC of high and low SCS sheep collected 12h post-challenge was performed on a 15K gene ovine oligoarray (Agilent). MSC were mainly neutrophils. The high number of differentially expressed genes between the two bacterial strains indicated, among others, increased number of T-cells in MSC after S. aureus, compared to S. epidermidis challenge. Differential regulation of 366 genes between resistant and susceptible animals was largely associated with immune and inflammatory response (including pathogen recognition TLR2 pathway and cell migration), signal transduction, cell proliferation and apoptosis. Close biological connection between most of differentially expressed genes into Ingenuity Pathway Analysis networks further indicated consistency between the genes that were differentially-expressed between resistant and susceptible animals. Gene profiling in high and low SCS sheep provided strong candidates for biological pathway and gene underlying genetically determined resistance and susceptibility towards Staphylococci infections opening new fields for further investigation. Keywords: Staphylococcus epidermidis, Staphylococcus aureus, milk somatic cells, mammalian, transcriptome, immunity, mastitis 22 samples in a two-colour dye-swap experimental design
Project description:Staphylococci are major pathogens in humans and animals and emerging antibiotic-resistant strains have further increased the importance of this health issue. The existence of a genetic basis of host response to bacterial infections has been widely documented but the underlying mechanisms and genes are still largely unknown. Previously, two divergent lines of sheep selected on their milk somatic cell count called high and low SCS lines, have been showed to be respectively more and less susceptible to intra mammary infections (IMI). Transcriptional profiling of milk somatic cells (MSC) of high and low SCS sheep infected successively by S. epidermidis and S. aureus was performed to provide enhanced knowledge about the genetic basis of differential host response to IMI with Staphylococci. Gene expression in MSC of high and low SCS sheep collected 12h post-challenge was performed on a 15K gene ovine oligoarray (Agilent). MSC were mainly neutrophils. The high number of differentially expressed genes between the two bacterial strains indicated, among others, increased number of T-cells in MSC after S. aureus, compared to S. epidermidis challenge. Differential regulation of 366 genes between resistant and susceptible animals was largely associated with immune and inflammatory response (including pathogen recognition TLR2 pathway and cell migration), signal transduction, cell proliferation and apoptosis. Close biological connection between most of differentially expressed genes into Ingenuity Pathway Analysis networks further indicated consistency between the genes that were differentially-expressed between resistant and susceptible animals. Gene profiling in high and low SCS sheep provided strong candidates for biological pathway and gene underlying genetically determined resistance and susceptibility towards Staphylococci infections opening new fields for further investigation. Keywords: Staphylococcus epidermidis, Staphylococcus aureus, milk somatic cells, mammalian, transcriptome, immunity, mastitis
Project description:In many pathogens, quorum-sensing systems regulate virulence. Quorum-sensing is therefore often proposed as a target for antivirulence drug development. Coagulase-negative staphylococci are leading causes of nosocomial blood infections and of mortality due to sepsis as the most extreme consequence of such infections. However, there is a severe lack of understanding how virulence and especially quorum-sensing affects coagulase-negative staphylococcal sepsis. Using a mouse systemic infection model, we here show that the staphylococcal Agr quorum-sensing system has a strong impact on mortality from sepsis caused by the exemplary coagulase-negative staphylococcal species Staphylococcus haemolyticus. To that end, we analyzed the mechanism and regulon of S. haemolyticus Agr, which revealed a strong focus of quorum-sensing regulation of phenol-soluble modulin toxins. Our results further indicate that PSMs are the virtually exclusive mediators of the Agr effect on S. haemolyticus sepsis and suggest that the predominant underlying mechanism is cytolytic capacity of PSMs. These findings imply that Agr and PSMs represent promising targets for antivirulence drug development targeting sepsis caused by coagulase-negative staphylococci. This contrasts quorum-sensing targeted efforts to control S. aureus blood infections, for which such approaches are considered less promising - a difference our results suggest is due to the much more focused role of Agr control in coagulase-negative staphylococci, where among toxins, Agr exclusively and exceptionally tightly controls PSMs.