Gene Expression Profiling of Dendritic Cells Reveals Important Mechanisms Associated with Predisposition to Staphylococcus Infections

Abstract

Background Staphylococcus aureus is a major pathogen of humans and animals and emerging antibiotic-resistant strains have further increased the concern of this health issue. Host genetics influence susceptibility to S. aureus infections, and the genes determining the outcome of infections should be identified to find alternative therapies to treatment with antibiotics. Here, we used outbred animals from a divergent selection based on susceptibility towards Staphylococcus infection to explore host immunogenetics.Methodology/Principal FindingsWe investigated how dendritic cells respond to heat-inactivated S. aureus and whether dendritic cells from animals showing different degrees of susceptibility had distinct gene expression profiles. We measured gene expression levels of in vitro S. aureus-stimulated bone marrow-derived dendritic cells at three different time points (0, 3 and 8 hrs) by using 15 k ovine Agilent microarrays. Furthermore, differential expression of a selected number of genes was confirmed by RT-qPCR. Gene signatures of stimulated DCs were obtained and showed that genes involved in the inflammatory process and T helper cell polarization were highly up-regulated upon stimulation. Moreover, a set of 204 genes were statistically differentially expressed between susceptible and resistant animals, and grouped them according to their predisposition to staphylococcal infection. Interestingly, over-expression of the C1q and Ido1 genes was observed in the resistant line and suggested a role of classical pathway of complement and early regulation of inflammation pathways, respectively. On the contrary, over expression of genes involved in the IL1R pathway was observed in susceptible animals. Furthermore, the leucocyte extravasation pathway was also found to be dominant in the susceptible line.Conclusion/SignificanceWe successfully obtained Staphylococcus aureus associated gene expression of ovine BM-DC in an 8-hour kinetics experiment. The distinct transcriptional profiles of dendritic cells obtained from resistant and susceptible animals may explain susceptibility towards S. aureus infections in a broader context.

Mastitis in sheep – The last 10 years and the future of research

“…These authors have suggested that, in selection of ewes for resistance to mastitis, use of reduced log-transformed somatic cell score may be employed as an indirect trait. Recently, Bonnefont et al (2011) andToufeer et al (2011) have used a 15 K ovine-specific microarray for transcriptional profiling to study the biological pathways and genes determining the underlying susceptibility and resistance against staphylococcal mammary infections, which would help identification of biological pathways and genes in mastitis resistance.…”

Genetic susceptibility to S. aureus mastitis in sheep: differential expression of mammary epithelial cells in response to live bacteria or supernatant

“…Methods were essentially as described before (54). Briefly, cDNA from all samples was preamplified using a pool of forward and reverse primers.…”

“…Our previous experiments are not in favor of these hypotheses. Indeed, the gene expression profiles of Staphylococcus spp-mastitis-resistant and -susceptible animals have already been studied in two other cell types: MSC collected after S. epidermidis or S. aureus inoculations of the mammary gland (8) and S. aureus-stimulated DC (54) with two groups of four (54) or six (8) sheep. In both cases significant differences were detected.…”

“…After intramammary inoculations of S. epidermidis or S. aureus, milk somatic cells (MSC) were collected for transcriptomic analysis (8). In vitro, dendritic cells (DC) were also analyzed after stimulation by S. aureus to describe gene reprogramming in cells of the monocytic lineage (54).…”

Enhanced immune response of BMDCs pulsed with H9N2 AIV and CpG

“…Recently, the gene expression profiling has been applied to exploration of host-pathogen interactions [12,13]. The identification of gene expression signatures indicative of virus subtypes using microarray technology has increased provided novel insights into the molecular basis of viral infection [12].…”