Suppressor of cytokine signaling-1 influences bacterial clearance and pathology during the infection with Mycobacterium tuberculosis
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ABSTRACT: Tuberculosis results from an interaction between a chronically persistent pathogen counteracted by IFN-g-mediated immune responses. Modulation of IFN-g signaling could therefore constitute a major immune evasion mechanism for M. tuberculosis. SOCS1 plays a major role in the inhibition of IFN-g-mediated responses. We found that M. tuberculosis infection stimulates SOCS1 expression in mouse and human myeloid cells. Significantly higher levels of SOCS1 were induced after in vitro or in vivo infection with virulent M. tuberculosis-than with attenuated M. bovis BCG. Different innate and adaptive immune mechanisms participated in infection-induced SOCS1 expression. SOCS1 hampered M. tuberculosis clearance both in macrophages and during murine infection in vivo. On the other hand, SOCS1 protected the host from an infection-induced inflammation. Despite SOCS1 expression, mycobacteria-infected macrophages were not tolerant to IFN-g. Instead, an impaired IFN-g secretion by macrophages, associated to lower responses to IL-12, accounted for the increased mycobacterial intracellular growth in presence of SOCS1. SOCS1 attenuated the expression of the majority of genes modulated by infection of macrophages (6,1% of the transcriptome), indicating the relevance of the molecule in the outcome of infection with M. tuberculosis. We suggest that SOCS1 is expressed during M. tuberculosis infection to establish a successful chronic infection, and dampen inflammatory damage. Difference in genotype and TB infection comparison
Project description:Tuberculosis results from an interaction between a chronically persistent pathogen counteracted by IFN-g-mediated immune responses. Modulation of IFN-g signaling could therefore constitute a major immune evasion mechanism for M. tuberculosis. SOCS1 plays a major role in the inhibition of IFN-g-mediated responses. We found that M. tuberculosis infection stimulates SOCS1 expression in mouse and human myeloid cells. Significantly higher levels of SOCS1 were induced after in vitro or in vivo infection with virulent M. tuberculosis-than with attenuated M. bovis BCG. Different innate and adaptive immune mechanisms participated in infection-induced SOCS1 expression. SOCS1 hampered M. tuberculosis clearance both in macrophages and during murine infection in vivo. On the other hand, SOCS1 protected the host from an infection-induced inflammation. Despite SOCS1 expression, mycobacteria-infected macrophages were not tolerant to IFN-g. Instead, an impaired IFN-g secretion by macrophages, associated to lower responses to IL-12, accounted for the increased mycobacterial intracellular growth in presence of SOCS1. SOCS1 attenuated the expression of the majority of genes modulated by infection of macrophages (6,1% of the transcriptome), indicating the relevance of the molecule in the outcome of infection with M. tuberculosis. We suggest that SOCS1 is expressed during M. tuberculosis infection to establish a successful chronic infection, and dampen inflammatory damage. Difference in genotype and TB infection comparison Relative gene expressions were determined by normalized intensity values. GeneSpring analysis was performed using the Treg transcriptome data with following comparisons: no GvHD d90 versus no GvHD d150, no GvHD d90 versus acute GvHD, no GvHD d150 versus chronic GvHD, acute GvHD versus chronic GvHD, acute GvHD versus GvHD d90 and chronic GvHD versus GvHD d150 (Figure 2). Cut-off was a transcript fold change of +2 or -2 in at least one comparison. Student´s t-test was used to identify significant expression changes.
Project description:Mycobacterium bovis is an intracellular pathogen that causes tuberculosis in cattle. Following infection, the pathogen resides and persists inside host macrophages by subverting host immune responses via a diverse range of mechanisms. Here, a high-density bovine microarray platform was used to examine the bovine monocyte-derived macrophage transcriptome response to M. bovis infection relative to infection with the attenuated vaccine strain, M. bovis Bacille CalmetteM-bM-^@M-^SGuM-CM-)rin. Differentially expressed genes were identified (adjusted P-value M-bM-^IM-$ 0.01) and interaction networks generated across an infection time course of 2, 6 and 24 h. The largest number of biological interactions was observed in the 24 h network, which exhibited small-worldscale-free network properties. The 24 h network featured a small number of key hub and bottleneck gene nodes, including IKBKE, MYC, NFKB1 and EGR1 that differentiated the macrophage response to virulent and attenuated M. bovis strains, possibly via the modulation of host cell death mechanisms. These hub and bottleneck genes represent possible targets for immunomodulation of host macrophages by virulent mycobacterial species that enable their survival within a hostile environment. Affymetrix GeneChipM-BM-. Bovine Genome Arrays were used to examine gene expression from a paired comparison of bovine monocyte-derived macrophages (MDM) after in vitro challenge with Mycobacterium bovis versus M. bovis BCG across a time series of 2 hr, 6 hr and 24 hr post-challenge.
Project description:Mycobacterium bovis is an intracellular pathogen that causes tuberculosis in cattle. Following infection, the pathogen resides and persists inside host macrophages by subverting host immune responses via a diverse range of mechanisms. Here, a high-density bovine microarray platform was used to examine the bovine monocyte-derived macrophage transcriptome response to M. bovis infection relative to infection with the attenuated vaccine strain, M. bovis Bacille Calmette–Guérin. Differentially expressed genes were identified (adjusted P-value ≤ 0.01) and interaction networks generated across an infection time course of 2, 6 and 24 h. The largest number of biological interactions was observed in the 24 h network, which exhibited small-worldscale-free network properties. The 24 h network featured a small number of key hub and bottleneck gene nodes, including IKBKE, MYC, NFKB1 and EGR1 that differentiated the macrophage response to virulent and attenuated M. bovis strains, possibly via the modulation of host cell death mechanisms. These hub and bottleneck genes represent possible targets for immunomodulation of host macrophages by virulent mycobacterial species that enable their survival within a hostile environment.
Project description:Currently, the only available vaccine against tuberculosis is Mycobacterium bovis Bacille Calmette-Guérin (BCG). Pulmonary tuberculosis protection provided by the vaccine varies depending on the strain, the patient’s age, and the evaluated population. Although the adaptive immune responses induced by different BCG strains have been widely studied, little conclusive data is available regarding innate immune responses, especially in macrophages. Here, we aimed to characterize the innate immune responses of human THP-1-derived macrophages at the transcriptional level following a challenge with either the BCG Mexico or Phipps strains. After a brief in vitro characterization of the bacterial strains and the innate immune responses, including nitric oxide production and cytokine profiles, we analyzed the mRNA expression patterns and performed pathway enrichment analysis using RNA microarrays. Our results showed that multiple biological processes were enriched, especially those associated with innate inflammatory and antimicrobial responses, including tumor necrosis factor (TNF)-α, type I interferon (IFN), and IFN-. These findings indicated the pro-inflammatory stimulation of macrophages induced by both BCG strains, at the cytokine level and in terms of gene expression. Our results demonstrated that both strains activated the innate immune response, with better modulation induced by BCG Phipps.
Project description:Despite wide scale vaccination with Mycobacterium bovis BCG, the prevalence of tuberculosis remains high, reflecting the global variable efficacy of this vaccine against adult pulmonary TB. Characterisation of different immune responses to M. tuberculosis and M. bovis BCG would increase understanding of pathology following M. tuberculosis infection or reactivation, and would facilitate the rational design of a new vaccine. Gene expression profiling was conducted on samples from diluted whole blood cultures from three healthy donors following incubation with live mycobacteria for six days. Approximately 8,000 gene entities were at least two-fold up- or down- regulated by the mycobacteria, and both mycobacteria induced similar expression changes in approximately 2,300 genes. Strikingly, many genes exhibited qualitatively different expression patterns, with over 1,000 genes up-regulated in response to M. bovis BCG but not changed by M. tuberculosis. Gene Ontology analysis revealed that the genes which failed to upregulate in M. tuberculosis-infected cultures included a large proportion of genes with lysosomal function. The inhibited up-regulation of expression of IFN-γ-inducible protein 30, acid phosphatase 2, cathepsin B and GM2 ganglioside activator was verified in samples from six biologically independent donors by qRT-PCR. The failure to up-regulate these genes in response to M. tuberculosis may constitute an immune evasion mechanism, preventing intracellular killing and antigen presentation. Blood from three healthy BCG-vaccinated donors was diluted with growth medium and incubated alone or with live M. tuberculosis (H37Rv), M. bovis BCG for 6 days. RNA samples were pooled before hybridisation.
Project description:Bovine tuberculosis, caused by Mycobacterium bovis, is a disease of considerable economic importance yet comparatively little is known about the bovine immune response to the disease. Alveolar macrophages are one of the first cells to encounter mycobacteria following infection. In this experiment we investigated the early transcriptional response of bovine alveolar macrophages following infection with M. bovis. The transcriptional response to heat-killed M. bovis was also investigated to look for genes that are only differentially transcribed in response to the live organism. Five-condition experiment, uninfected, live and heat-killed M. bovis-infected bovine alveolar macrophages from five cattle infected for two and four hours. Comparisons were within animal. Dye swaps were incorporated into the design.
Project description:Bovine tuberculosis, caused by Mycobacterium bovis, is a disease of considerable economic importance yet comparatively little is known about the bovine immune response to the disease. Alveolar macrophages are one of the first cells to encounter mycobacteria following infection. In this experiment we investigated the early transcriptional response of bovine alveolar macrophages following infection with M. bovis. The transcriptional response to heat-killed M. bovis was also investigated to look for genes that are only differentially transcribed in response to the live organism.
Project description:Macrophages from cattles with different infectious status of bovine tuberculosis have different responses to in vitro Mycobacterium bovis challenge. This is confirmed in our previous study exploring several immune-related genes using qPCR. Microarrays can help us better understand the differences by screening thousands of genes. Monocytes Derived Macrophages from 3 TB-infected cattles and 3 TB-free cattles were challenged with Mycobacterium bovis at a MOI of 10 at 6 hours, and the control group were the same unchallenged macrophages at 6 hours.
Project description:Despite wide scale vaccination with Mycobacterium bovis BCG, the prevalence of tuberculosis remains high, reflecting the global variable efficacy of this vaccine against adult pulmonary TB. Characterisation of different immune responses to M. tuberculosis and M. bovis BCG would increase understanding of pathology following M. tuberculosis infection or reactivation, and would facilitate the rational design of a new vaccine. Gene expression profiling was conducted on samples from diluted whole blood cultures from three healthy donors following incubation with live mycobacteria for six days. Approximately 8,000 gene entities were at least two-fold up- or down- regulated by the mycobacteria, and both mycobacteria induced similar expression changes in approximately 2,300 genes. Strikingly, many genes exhibited qualitatively different expression patterns, with over 1,000 genes up-regulated in response to M. bovis BCG but not changed by M. tuberculosis. Gene Ontology analysis revealed that the genes which failed to upregulate in M. tuberculosis-infected cultures included a large proportion of genes with lysosomal function. The inhibited up-regulation of expression of IFN-γ-inducible protein 30, acid phosphatase 2, cathepsin B and GM2 ganglioside activator was verified in samples from six biologically independent donors by qRT-PCR. The failure to up-regulate these genes in response to M. tuberculosis may constitute an immune evasion mechanism, preventing intracellular killing and antigen presentation.
Project description:In this study we compared the transcriptome of bovine macrophages infected with two Mycobacterium bovis strains of variable virulence, co-cultured with autologous lymphocytes. We used the highly virulent M. bovis strain called Mb04-303 and the attenuated Mb534 strain. We first observed that only the infection of bovine macrophages with the virulent strain, Mb04-303, induced in peripheral bovine mononuclear cells a powerful innate immune response capable of controlling the intracellular mycobacterial replication.By RNAseq analysis we found that infections with Mb04-303 downregulated the KEAP1-NFE2L2 pathway that encodes a transcriptional factor involved in antioxidant genes and inflammasome activation and upregulated the type 1 interferon signalling pathway, compared to the infections with the attenuated Mb534 strain. T