Project description:Background: Mycobacterium avium subspecies paratuberculosis (MPTb) is the causative agent of Johne’s disease, an intestinal disease of ruminants with major economic consequences. MPTb bacilli are phagocytosed by host macrophages upon exposure where they persist, resulting in lengthy subclinical phases of infection that can lead to immunopathology and disease dissemination. Consequently, analysis of the macrophage transcriptome in response to MPTb infection can provide valuable insights into the molecular mechanisms that underlie Johne’s disease. Here, we investigate pan-genomic gene expression in bovine monocyte-derived macrophages (MDM) purified from seven age-matched non-related females, in response to in vitro infection with MPTb (multiplicity of infection 2:1) at intervals of 2 hours, 6 hours and 24 hours post-infection. Results: Differentially expressed genes were identified by comparing the transcriptomes of the infected MDM to the control MDM at each time point (adjusted P-value threshold ≤ 0.10). 1,050 differentially expressed unique genes were identified 2 hours post-infection, with 974 and 84 differentially expressed unique genes detected 6 hours and 24 hours post-infection, respectively. Furthermore, in the infected MDM the number of upregulated genes exceeded the number of downregulated genes at each time point, with the fold-change in expression for the upregulated genes markedly higher than that for the downregulated genes. Conclusions: Inspection and systems analysis of the differentially expressed genes revealed changes in the expression profiles of genes involved in the inflammatory response, cell signalling pathways and apoptosis. The transcriptional changes associated with cellular signalling and the inflammatory response may reflect different immuno-modulatory mechanisms that underlie host-pathogen interactions during infection. Affymetrix GeneChip® Bovine Genome Arrays were used to examine gene expression of bovine monocyte-derived macrophages (MDM) after in vitro challenge with Mycobacterium avium subspecies paratuberculosis across a time series of 2 hr, 6 hr and 24 hr post-challenge. A 0 hr control treatment was also generated and seven different age-matched female Holstein-Friesian cattle were used for each time-point/treatment combination for a total of 49 microarrays, one of which was excluded from analysis since it did not pass quality control.

Project description:Background: Johne’s disease is a chronic wasting disease caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Johne’s disease is highly contagious and MAP infection in dairy cattle can eventually lead to death. With no available treatment for Johne’s disease, genetic selection and improvements in management practices could help reduce its prevalence. In a previous study, the gene coding interleukin-10 receptor subunit alpha (IL10Rα) was associated with Johne’s disease in dairy cattle. Our objective was to determine how IL10Rα affects the pathogenesis of MAP by examining the effect of a live MAP challenge on a mammary epithelial cell line (MAC-T) that had IL10Rα knocked out using CRISPR/cas9. The wild type and the IL10Rα knockout MAC-T cell lines were exposed to live MAP bacteria for 48 hours. Thereafter, mRNA was extracted from infected and uninfected cells. Differentially expressed genes were compared between the wild type and the IL10Rα knockout cell lines. Gene ontology was performed based on the differentially expressed genes to determine which biological pathways were involved. Results: Immune system processes pathways were targeted to determine the effect of IL10Rα on the response to MAP infection. There was a difference in immune response between the wild type and IL10Rα knockout MAC-T cell lines, and little difference in immune response between infected and not infected IL10Rα knockout MAC-T cells, indicating IL10Rα plays an important role in the progression of MAP infection. Additionally, these comparisons allowed us to identify other genes involved in inflammation-mediated chemokine and cytokine signalling, interleukin signalling and toll-like receptor pathways. Conclusions: Identifying differentially expressed genes in wild type and ILR10α knockout MAC-T cells infected with live MAP bacteria provided further evidence that IL10Rα contributes to mounting an immune response to MAP infection and allowed us to identify additional potential candidate genes involved in this process. We found there was a complex immune response during MAP infection that is controlled by many genes.

Project description:Background: Mycobacterium bovis, the causative agent of bovine tuberculosis, is a major cause of mortality in global cattle populations. Macrophages are among the first cells types to encounter M. bovis following exposure and the response elicited by these cells is pivotal in determining the outcome of infection. Here, a functional genomics approach was undertaken to investigate global gene expression profiles in bovine monocyte-derived macrophages (MDM) purified from seven age-matched non-related females, in response to in vitro challenge with M. bovis (multiplicity of infection 2:1). Total cellular RNA was extracted from non-challenged control and M. bovis-challenged MDM for all animals at intervals of 2 hours, 6 hours and 24 hours post-challenge and prepared for global gene expression analysis using the Affymetrix® GeneChip® Bovine Genome Array. Results: Comparison of M. bovis-challenged MDM gene expression profiles with the non-challenged MDM controls at each time point identified 3,529 differentially expressed genes after 2 hours post-challenge, with 5,211 and 6,150 differentially expressed genes detected at the 6 hour and 24 hour time points, respectively (adjusted P-value threshold ≤ 0.05). Notably, the number of downregulated genes exceeded the number of upregulated genes in the M. bovis-challenged MDM across all time points; however, the fold-change in expression for the upregulated genes was markedly larger than that for the downregulated genes. Systems analysis revealed enrichment for genes involved in: (1) the inflammatory response; (2) cell signalling pathways, including Toll-like receptors and intracellular pathogen recognition receptors (PRRs)-receptors; and (3) apoptosis. Conclusions: The increased number of downregulated genes is consistent with previous studies showing that M. bovis infection is associated with the repression of host gene expression. The results also support important roles for MYD88-independent signalling and intracellular PRRs in mediating the host response to M. bovis, which to our knowledge have not been reported previously.

Project description:Background: MycobacteriumM-BM- bovis, the causative agent of bovine tuberculosis, is an intracellular pathogen that can persist inside host macrophages during infection via a diverse range of mechanisms that subvert the host immune response. In the current study, we have analysed and compared the transcriptomes of M.M-BM- bovis-infected monocyte-derived macrophages (MDM) purified from six Holstein-Friesian females with the transcriptomes of non-infected control MDM from the same animals over a 24 h period using strand-specific RNA sequencing (RNA-seq). In addition, we compare gene expression profiles generated using RNA-seq with those previously generated by us using the high-density AffymetrixM-BM-. GeneChipM-BM-. Bovine Genome Array platform from the same MDM-extracted RNA. Results: A mean of 7.2 million reads from each MDM sample mapped uniquely and unambiguously to single BosM-BM- taurus reference genome locations. Analysis of these mapped reads showed 2,584 genes (1,392 upregulated; 1,192 downregulated) and 757 putative natural antisense transcripts (558 upregulated; 119 downregulated) that were differentially expressed based on sense and antisense strand data, respectively (adjusted P-value M-bM-^IM-$ 0.05). Of the differentially expressed genes, 694 were common to both the sense and antisense data sets, with the direction of expression (i.e. up- or downregulation) positively correlated for 693 genes and negatively correlated for the remaining gene. Gene ontology analysis of the differentially expressed genes revealed an enrichment of immune, apoptotic and cell signalling genes. Notably, the number of differentially expressed genes identified from RNA-seq sense strand analysis was greater than the number of differentially expressed genes detected from microarray analysis (2,584 genes versus 2,015 genes). Furthermore, our data reveal a greater dynamic range in the detection and quantification of gene transcripts for RNA-seq compared to microarray technology.M-BM- Conclusions: This study highlights the value of RNA-seq in identifying novel immunomodulatory mechanisms that underlie host-mycobacterial pathogen interactions during infection, including possible complex post-transcriptional regulation of host gene expression involving antisense RNA. Description of the transcriptomic host response after infection of bovine monocyte-derived macrophages with Mycobacterium bovis

Project description:Background: Mycobacterium bovis, the causative agent of bovine tuberculosis, is a major cause of mortality in global cattle populations. Macrophages are among the first cells types to encounter M. bovis following exposure and the response elicited by these cells is pivotal in determining the outcome of infection. Here, a functional genomics approach was undertaken to investigate global gene expression profiles in bovine monocyte-derived macrophages (MDM) purified from seven age-matched non-related females, in response to in vitro challenge with M. bovis (multiplicity of infection 2:1). Total cellular RNA was extracted from non-challenged control and M. bovis-challenged MDM for all animals at intervals of 2 hours, 6 hours and 24 hours post-challenge and prepared for global gene expression analysis using the Affymetrix® GeneChip® Bovine Genome Array. Results: Comparison of M. bovis-challenged MDM gene expression profiles with the non-challenged MDM controls at each time point identified 3,529 differentially expressed genes after 2 hours post-challenge, with 5,211 and 6,150 differentially expressed genes detected at the 6 hour and 24 hour time points, respectively (adjusted P-value threshold ≤ 0.05). Notably, the number of downregulated genes exceeded the number of upregulated genes in the M. bovis-challenged MDM across all time points; however, the fold-change in expression for the upregulated genes was markedly larger than that for the downregulated genes. Systems analysis revealed enrichment for genes involved in: (1) the inflammatory response; (2) cell signalling pathways, including Toll-like receptors and intracellular pathogen recognition receptors (PRRs)-receptors; and (3) apoptosis. Conclusions: The increased number of downregulated genes is consistent with previous studies showing that M. bovis infection is associated with the repression of host gene expression. The results also support important roles for MYD88-independent signalling and intracellular PRRs in mediating the host response to M. bovis, which to our knowledge have not been reported previously. Affymetrix GeneChip® Bovine Genome Arrays were used to examine gene expression of bovine monocyte-derived macrophages (MDM) after in vitro challenge with Mycobacterium bovis across a time series of 2 hr, 6 hr and 24 hr post-challenge. A 0 hr control treatment was also generated and seven different age-matched female Holstein-Friesian cattle were used for each time-point/treatment combination for a total of 49 microarrays.

Project description:Background: Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) is the causative agent of Johne’s disease, a chronic enteric infection of ruminants. Infection occurs within the first few months of life but remains subclinical for an average of 2-5 years. Current diagnostics to detect early subclinical infections lack diagnostic sensitivity, which hinders disease control resulting in significant economic losses to the dairy industry worldwide. The pathophysiology of early infection with M. paratuberculosis is still not well understood and represents a key hurdle towards the development of better diagnostics. Methods: The present study employed a large-scale RNA-Sequencing technology to better understand early stages of M. paratuberculosis infection and immunization. Specifically, gene expression profiles of peripheral blood mononuclear cells (PBMCs) from infected and vaccinated goats were compared to controls. Results: The transcriptome of the control goats revealed a large number of genes (N = 226, 1018, 1714, 1133) that were differentially expressed compared to the M. paratuberculosis-infected goats, goats vaccinated with live attenuated or inactivated vaccines, and goats both vaccinated and infected. Bioinformatics evaluation of the differentially expressed genes indicated the regulation of a large number of genes with immunity and inflammatory functions including IL-18BP, IFN-γ, IL-17A, NOS2, LIPG and IL-22. Interestingly, a large number of goat genes (N=667) were regulated whether live or inactivated vaccine were used. Some of the regulated genes (e.g. IL-17A, IFN-g) continued its unique transcriptional profile up to 12 months post-challenge. Conclusions: Overall, transcriptome analysis of infected and/or immunized goats identified potential targets for developing early diagnostics for Johne’s disease and a potential approach to differentiate infected from vaccinated animals. A similar approach could be used to analyze later stages of Johne’s disease or other chronic infections.

Project description:Background: Mycobacterium bovis, the causative agent of bovine tuberculosis, is an intracellular pathogen that can persist inside host macrophages during infection via a diverse range of mechanisms that subvert the host immune response. In the current study, we have analysed and compared the transcriptomes of M. bovis-infected monocyte-derived macrophages (MDM) purified from six Holstein-Friesian females with the transcriptomes of non-infected control MDM from the same animals over a 24 h period using strand-specific RNA sequencing (RNA-seq). In addition, we compare gene expression profiles generated using RNA-seq with those previously generated by us using the high-density Affymetrix® GeneChip® Bovine Genome Array platform from the same MDM-extracted RNA. Results: A mean of 7.2 million reads from each MDM sample mapped uniquely and unambiguously to single Bos taurus reference genome locations. Analysis of these mapped reads showed 2,584 genes (1,392 upregulated; 1,192 downregulated) and 757 putative natural antisense transcripts (558 upregulated; 119 downregulated) that were differentially expressed based on sense and antisense strand data, respectively (adjusted P-value ≤ 0.05). Of the differentially expressed genes, 694 were common to both the sense and antisense data sets, with the direction of expression (i.e. up- or downregulation) positively correlated for 693 genes and negatively correlated for the remaining gene. Gene ontology analysis of the differentially expressed genes revealed an enrichment of immune, apoptotic and cell signalling genes. Notably, the number of differentially expressed genes identified from RNA-seq sense strand analysis was greater than the number of differentially expressed genes detected from microarray analysis (2,584 genes versus 2,015 genes). Furthermore, our data reveal a greater dynamic range in the detection and quantification of gene transcripts for RNA-seq compared to microarray technology. Conclusions: This study highlights the value of RNA-seq in identifying novel immunomodulatory mechanisms that underlie host-mycobacterial pathogen interactions during infection, including possible complex post-transcriptional regulation of host gene expression involving antisense RNA.

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Pan-genomic analysis of bovine monocyte-derived macrophage gene expression in response to in vitro infection with Mycobacterium avium subspecies paratuberculosis

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