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Transcriptomic analysis of milk somatic cells in mastitis resistant and susceptible sheep upon challenge with Staphylococcus epidermidis and Staphylococcus aureus

ABSTRACT: 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

ORGANISM(S): Ovis aries

PROVIDER: GSE24925 | GEO | 2011/10/01

SECONDARY ACCESSION(S): PRJNA132179

REPOSITORIES: GEO

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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:Periprosthetic joint infection (PJI), a devastating complication of total joint replacement, is of incompletely understood pathogenesis and may sometimes be challenging to clinically distinguish from other causes of arthroplasty failure. We characterized human gene expression in 93 specimens derived from surfaces of resected arthroplasties, comparing transcriptomes of subjects with infection- versus non-infection-associated arthroplasty failure. Differential gene expression analysis confirmed 28 previously reported potential biomarkers of PJI, including bactericidal/permeability increasing protein (BPI), cathelicidin antimicrobial peptide (CAMP), C-C-motif chemokine ligand 3 (CCL3), 4(CCL4), and C-X-C-motif chemokine ligand 2 (CXCL2), colony stimulating factor 2 receptor beta (CSF2RB), colony stimulating factor 3 (CSF3), alpha-defensin (DEFA4), Fc fragment of IgG receptor 1B (CD64B), intercellular adhesion molecule 1 (ICAM1), interferon gamma (IFNG), interleukin 13 receptor subunit alpha 2 (IL13RA2), interleukin 17D (IL17D), interleukin 1 (IL1A, IL1B, IL1RN), interleukin 2 receptors (IL2RA, IL2RG), interleukin 5 receptor (IL5RA), interleukin 6 (IL6), interleukin 8 (IL8), lipopolysaccharide binding protein (LBP), lipocalin (LCN2), lactate dehydrogenase C (LDHC), lactotransferrin (LTF), matrix metallopeptidase 3 (MMP3), peptidase inhibitor 3 (PI3), and vascular endothelial growth factor A (VEGFA), and identified three novel molecules of potential diagnostic use for detection of PJI, namely C-C-motif chemokine ligand CCL20, coagulation factor VII (F7), and B cell receptor FCRL4. Comparative analysis of infections caused by staphylococci versus bacteria other than staphylococci and Staphylococcus aureus versus Staphylococcus epidermidis showed elevated expression of interleukin 13 (IL13), IL17D, and MMP3 in staphylococcal infections, and of IL1B, IL8, and platelet factor PF4V1 in S. aureus compared to S. epidermidis infections. Pathway analysis of over-represented genes suggested activation of host immune response and cellular maintenance and repair functions in response to invasion of infectious agents. The data presented provides new potential targets for diagnosis of PJI and for differentiation of PJI caused by different infectious agents.

Project description:Mastitis is an inflammation of the mammary gland (MG), usually due to bacterial infection. Although considerable attention has been paid to this economically important disease, the early stages of the host response remain poorly defined. In particular, it is unclear how mammary epithelial cells (MEC), a first barrier against pathogens, respond to infection. Indeed, it is difficult to differentiate between the contributions of MEC and infiltrating immune cells to gene expression profiles of mammary tissue during mastitis. The current investigation examines the response of MEC at the early stage of infection using a non invasive RNA sampling method taking advantage of the presence of cytoplasmic crescents contained in milk fat globules. We have recently shown that, in goats, Milk Fat Globules (MFG) provide a unique source of RNA to study the in vivo regulation of gene expression in MEC. This non invasive RNA sampling method was used during the time course of an experimental intra mammary infection (IMI) with S. aureus. Experiments were performed using ovine microarrays (Agilent) to compare gene expression patterns before infection, at 12h, 18h and 24h post-infection (PI). Furthermore, we combined this approach with laser capture microdissection of MEC isolated from frozen slides of mammary tissue to study some specific genes at the late stage of infection (30h PI). We show that at 18h PI, before the burst of somatic cells in milk, MEC play an important role in the recruitment and activation of inflammatory cells through the IL-8 signaling pathways. Then, at the late stage of infection (30h PI), the contribution of MEC in immune response changes to produce different acute phase proteins, including SAA3, serpin A1 and PTX3. These cells also express factors that contribute directly to fighting infection, such as S100A12. In summary, we demonstrate for the first time in vivo how MEC orchestrate innate immune response during an IMI with S. aureus in the goat species. We report here new opportunities to assess the dynamics of gene expression in the mammary gland, thus providing significant advances in the understanding of MEC immune capacity.M-bM-^@M-^BFurthermore, the production of some molecules by MEC, in the early stages of IMI, could provide sensitive biomarkers for early detection and therefore, treatment of mastitis. Experiments were performed using ovine microarrays (Agilent) to compare gene expression patterns before infection, at 12h, 18h and 24h post-infection (PI). 20 sample records; mono-colour experimental design

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Transcriptomic analysis of milk somatic cells in mastitis resistant and susceptible sheep upon challenge with Staphylococcus epidermidis and Staphylococcus aureus

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