Project description:Staphylococcus aureus lipoteichoic acid (aLTA) and Lactobacillus plantarum LTA (pLTA) engage the same Toll-like receptor 2 (TLR2) signaling pathway, but exert different effects on the innate immune/inflammatory responses. aLTA is the leading cause of gram-positive bacterial sepsis induced by S. aureus, whereas pLTA is considered as a promising therapeutic agent for pathogen-induced septic shock. The mechanisms underlying the different functions of aLTA and pLTA remain unclear. We used human oligo microarrays to investigate the transcriptomes of human THP-1 monocytes upon exposure to aLTA and pLTA. Differential gene expression profiles were observed between the aLTA- and pLTA-treated cells. The expression levels of 1301 genes in aLTA-treated cells were changed more than 2 fold. These genes are critically involved in immune/inflammatory responses, cell adhesion, cell signal transduction, transcription factors, anion transport, proteolysis and oxidative processes. Especially, a variety of genes that encode cytokines/chemokines and other related molecules such as those belonging to the IRAK, TRAF, NF-κB, and STAT families were remarkably up-regulated by aLTA stimulation. In contrast, the expression levels of only 93 genes were altered by more than 1.5 fold in pLTA-treated cells, and these genes are almost not correlative with immune/inflammatory responses and other related processes compared with those of aLTA-treated cells. The different functions of aLTA and pLTA were further compared with the differential expressions of a selected group of genes, i.e., IRAKs, TRAFs and some cytokines/chemokines through RT-PCR and ELISA assays. The gene expression of IRAK2 could be markedly induced by aLTA, but significantly inhibited by pLTA treatment. These results suggest that the different functions of aLTA and pLTA on innate immunity and inflammation might be due to their different effects on the expression of some genes related with the innate immune/inflammatory responses, such as IRAK2 etc.

Project description:Differential response of bovine mammary epithelial cells to Staphylococcus aureus or Escherichia coli agonists of the innate immune system. Mastitis caused by Escherichia coli and Staphylococcus aureus is a major pathology of dairy cows. To better understand the differential response of the mammary gland to these two pathogens, we stimulated bovine mammary epithelial cells (bMEC) with either E. coli crude lipopolysaccharide (LPS) or with S. aureus culture supernatant (SaS) to compare the transcriptomic profiles of the initial bMEC response (3 and 6 h of exposure to agonists). By using HEK 293 cells transfected with human pattern recognition receptors, the LPS preparation was found to stimulate TLR2 and TLR4 but not TLR5, Nod1 or Nod2, whereas SaS stimulated TLR2. Biochemical analysis revealed that lipoteichoic acid, protein A and alpha-hemolysin were all present in SaS, and bMEC were found to be responsive to each of these molecules. Transcriptome profiling by a microarray and confirmation by RT-qPCR revealed an innate immune response which was common to both LPS and SaS. However, LPS induced expression of a significant higher number of genes and the fold changes were of greated magnitude than those induced by SaS. Overall, the analysis of microarray data suggests that the activation pathways and the early chemokine and cytokine production preceded the defense and stress responses. Chemokines were among the most up-regulated genes, in particular ELRCXC chemokines that target neutrophils. A major differential response was the activation of the type I IFN pathway by LPS but not by SaS. This was in accordance with the much stronger up-regulation of Cxcl10, Ccl5 and Nos2 by LPS than by SaS. The higher upregulation of chemokines that target mononuclear leucocytes (CXCL10, CCL2, CCL5 and CCL20) by LPS than by SaS is likely to be related to the differential activation of the type I IFN pathway, and could induce a different profile of the initial recruitment of leucocytes. It is noteworthy that at the protein level, secretion of TNF-alpha and IL-1-beta was not induced by either stimulus. These results suggest that the response of MEC to diffusible bacterial stimuli is able to contribute to the onset of the response with differential leucocyte recruitment but does not account directly for the differential production of major pro-inflammatory cytokines. Transcriptional profiling of bovine mammary epithelial cells (Holstein breed) comparing untreated control with mammary epithelial cells (MECs) stimulated by Staphylococcus aureus (SA) versus Escherichia coli lipopolysaccharide (LPS). 16 microarrays (2 stimuli * 2 times * quadruplicate) in a two-color dye-swap experimental design. Untreated cells served as the control. One replicate per array. Log2-intensity of each dye was analyzed separately => 32 samples.

Project description:Differential response of bovine mammary epithelial cells to Staphylococcus aureus or Escherichia coli agonists of the innate immune system. Mastitis caused by Escherichia coli and Staphylococcus aureus is a major pathology of dairy cows. To better understand the differential response of the mammary gland to these two pathogens, we stimulated bovine mammary epithelial cells (bMEC) with either E. coli crude lipopolysaccharide (LPS) or with S. aureus culture supernatant (SaS) to compare the transcriptomic profiles of the initial bMEC response (3 and 6 h of exposure to agonists). By using HEK 293 cells transfected with human pattern recognition receptors, the LPS preparation was found to stimulate TLR2 and TLR4 but not TLR5, Nod1 or Nod2, whereas SaS stimulated TLR2. Biochemical analysis revealed that lipoteichoic acid, protein A and alpha-hemolysin were all present in SaS, and bMEC were found to be responsive to each of these molecules. Transcriptome profiling by a microarray and confirmation by RT-qPCR revealed an innate immune response which was common to both LPS and SaS. However, LPS induced expression of a significant higher number of genes and the fold changes were of greated magnitude than those induced by SaS. Overall, the analysis of microarray data suggests that the activation pathways and the early chemokine and cytokine production preceded the defense and stress responses. Chemokines were among the most up-regulated genes, in particular ELRCXC chemokines that target neutrophils. A major differential response was the activation of the type I IFN pathway by LPS but not by SaS. This was in accordance with the much stronger up-regulation of Cxcl10, Ccl5 and Nos2 by LPS than by SaS. The higher upregulation of chemokines that target mononuclear leucocytes (CXCL10, CCL2, CCL5 and CCL20) by LPS than by SaS is likely to be related to the differential activation of the type I IFN pathway, and could induce a different profile of the initial recruitment of leucocytes. It is noteworthy that at the protein level, secretion of TNF-alpha and IL-1-beta was not induced by either stimulus. These results suggest that the response of MEC to diffusible bacterial stimuli is able to contribute to the onset of the response with differential leucocyte recruitment but does not account directly for the differential production of major pro-inflammatory cytokines.

Project description:Fribourg2014 - Dynamics of viral antagonism and innate immune response (H1N1 influenza A virus - Cal/09) The dynamics of the interplay between the viral antagonism and the innate immune response has been studied using modelling approaches. The responses of human monocyte-derived dendritic cells infected by two influenza A H1N1 strains (the pandemic swine-origin A/California/4/2009 (Cal/09) and the seasonal A/New Caledonia/20/1999 (NC/99)) that have different clinical outcomes have been modelled. From the time course gene expression measurements of a set of selected genes, the dynamic features of viral antagonism and innate immune response are extracted. It is found that the strength and the time scale of action of viral antagonism is significantly different between the two viruses. This model describes the viral infection by seasonal Cal/09. This model is described in the article: Model of influenza A virus infection: Dynamics of viral antagonism and innate immune response. Fribourg M, Hartmann B, Schmolke M, Marjanovic N, Albrecht RA, García-Sastre A, Sealfon SC, Jayaprakash C, Hayot F. J Theor Biol. 2014 Mar 2;351C:47-57. Abstract: Viral antagonism of host responses is an essential component of virus pathogenicity. The study of the interplay between immune response and viral antagonism is challenging due to the involvement of many processes acting at multiple time scales. Here we develop an ordinary differential equation model to investigate the early, experimentally measured, responses of human monocyte-derived dendritic cells to infection by two H1N1 influenza A viruses of different clinical outcomes: pandemic A/California/4/2009 and seasonal A/New Caledonia/20/1999. Our results reveal how the strength of virus antagonism, and the time scale over which it acts to thwart the innate immune response, differs significantly between the two viruses, as is made clear by their impact on the temporal behavior of a number of measured genes. The model thus sheds light on the mechanisms that underlie the variability of innate immune responses to different H1N1 viruses. This model is hosted on BioModels Database and identified by: MODEL1403310002. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Profiling the gene expression for aLTA and pLTA effect in THP1

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