Project description:Background: Staphylococcus aureus is a major pathogen of humans and animals and rapidly emerging antibiotic-resistant strains have further increased the severity of this health issue. Host genetics influence susceptibility to S. aureus infections, and genes determining infection outcome should be identified to analyze immune-based therapies as an alternative to antibiotics. Here, we used outbred animals from a divergent selection on susceptibility towards Staphylococcus infection to explore host immunogenetics. Methodology/Principal Findings: We investigated how dendritic cells respond to heat-inactivated S. aureus and whether dendritic cells from animals with different degree of susceptibility have distinct gene expression profiles. We measured expression levels of 15K probes from in vitro S. aureus-stimulated bone marrow-derived dendritic cells at three different time points (0, 3 and 8 hours) by using Agilent microarrays. Furthermore, a selected number of genes were confirmed by RT-qPCR. Gene signatures of stimulated DCs were obtained and genes involved in inflammatory process and T helper cell polarization were highly up regulated upon stimulation. Moreover, a set of 204 genes were statistically different between susceptible and resistant animals, and grouped them according to their predisposition to staphylococcal infection. Interestingly, a role of classical pathway of Complement and early regulation of inflammation is observed in the resistant line through over expression of C1q and Ido1 genes respectively. On the opposite, over expression of genes in the IL1R pathway in the susceptible animals was noticed. Furthermore, leucocyte extravasation pathway was also found dominant in the susceptible line. Conclusion/Significance: we successfully obtained Staphylococcus aureus associated gene expression of ovine BM-DC in 8 hour kinetics experiment. Distinct transcriptional profiles of dendritic cells obtained from resistant and susceptible lines may explain susceptibility towards S. aureus infections in a broad context. Keywords: Staphylococcus aureus, dendritic cells, mammalian, transcriptome, immunity, mastitis 44 sample records; two-colour dye-swap experimental design

Project description:Background: Staphylococcus aureus is a major pathogen of humans and animals and rapidly emerging antibiotic-resistant strains have further increased the severity of this health issue. Host genetics influence susceptibility to S. aureus infections, and genes determining infection outcome should be identified to analyze immune-based therapies as an alternative to antibiotics. Here, we used outbred animals from a divergent selection on susceptibility towards Staphylococcus infection to explore host immunogenetics. Methodology/Principal Findings: We investigated how dendritic cells respond to heat-inactivated S. aureus and whether dendritic cells from animals with different degree of susceptibility have distinct gene expression profiles. We measured expression levels of 15K probes from in vitro S. aureus-stimulated bone marrow-derived dendritic cells at three different time points (0, 3 and 8 hours) by using Agilent microarrays. Furthermore, a selected number of genes were confirmed by RT-qPCR. Gene signatures of stimulated DCs were obtained and genes involved in inflammatory process and T helper cell polarization were highly up regulated upon stimulation. Moreover, a set of 204 genes were statistically different between susceptible and resistant animals, and grouped them according to their predisposition to staphylococcal infection. Interestingly, a role of classical pathway of Complement and early regulation of inflammation is observed in the resistant line through over expression of C1q and Ido1 genes respectively. On the opposite, over expression of genes in the IL1R pathway in the susceptible animals was noticed. Furthermore, leucocyte extravasation pathway was also found dominant in the susceptible line. Conclusion/Significance: we successfully obtained Staphylococcus aureus associated gene expression of ovine BM-DC in 8 hour kinetics experiment. Distinct transcriptional profiles of dendritic cells obtained from resistant and susceptible lines may explain susceptibility towards S. aureus infections in a broad context. Keywords: Staphylococcus aureus, dendritic cells, mammalian, transcriptome, immunity, mastitis

Project description:Bovine mastitis, an inflammatory reaction of the mammary gland, is commonly caused by Staphylococcus aureus or Escherichia coli infections in high-yielding dairy cows. Immunotranscriptomic responses of bovine mammary epithelial cell (bMEC) are pivotal for the understanding of the defense against invading pathogens, and for the fate of udder inflammation. The intracellular chemotaxic protein Cyclophilin A (CyPA), secreted by bMEC during inflammatory reaction is being considered as a marker for the early diagnosis of mastitis. Taken together, the present study aimed to investigate the microarray-based transcriptome alterations in bMEC after in vitro infection with two S. aureus strains (S. aureus JE2 and S. aureus SA003) or E. coli crude lipopolysaccharide (LPS). In addition, the CyPA-induced expression changes of selected cytokine and chemokines were evaluated by qRT-PCR. Differential expression analysis identified 447, 465 and 520 differentially expressed genes (DEGs) in bMEC after LPS, S. aureus JE2 and S. aureus SA003 stimulation, respectively. LPS-induced DEGs are involved in the activation of cytokine-cytokine receptors interaction, NOD-like receptor signaling, chemokine signaling, interleukin-1 signaling and Toll-like receptor signaling pathway; while S. aureus induced DEGs were involved in the enrichment of neuroactive ligand-receptor interaction, GPCR signaling, cytokine-cytokine receptor interaction, and JAK-STAT pathway. A major differential inflammatory response to LPS and S. aureus treatments was the activation of the chemokine signaling pathway by LPS but not either by S. aureus JE2 or SA003. Unlike the S. aureus strains, LPS stimulation resulted significant upregulation of CCL2, CXCL2, CXCL3, CXCL5, CXCL8, CXCL9, IL1A and IL1B that are known to target mononuclear leukocytes, and could induce systemic inflammation. CyPA stimulation was able to upregulate chemokines (CXCL2, CXCL3, CXCL8, IL1A and IL1B) expression in bMEC indicating its ability to promote inflammation. Several of the LPS-induced DEGs were found to have transcription factor binding sites, and their expressions were also predicted to be regulated by sets of microRNAs. The transcriptional alterations associated with inflammatory response in this study may reflect immunomodulatory mechanisms underlying the interaction of bMEC with E. coli and S. aureus during mastitis.

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High throughput transcriptomics analysis of ovine mammary epithelial cells stimulated with Staphylococcus aureus in vitro

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