Project description:Increasing evidence highlights the role of bacteria in the physiopathology of cancer. However, the underlying molecular mechanisms remains poorly understood. Several cancer-associated bacteria have been shown to produce toxins which modulate the tumor suppressor p53 and thereby interfere with the host defense against tumorigenesis. Here, we show that lipopolysaccharides from Klebsiella pneumoniae (Kp) strongly inhibit the host p53 pathway and impairs p53 transcriptional activity upon DNA damage and oncogenic stress, preventing its tumor suppressive function.
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappa-B, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: Differential expression, innate immunity, pneumonia, immunocompromised host; lung epithelium, in vitro, MLE-15 cells were treated with sham (PBS), NTHi lysate (100 ug/ml) or EF2505-III (40 ug/ml). 4 unique samples per group. Treated for 2 hours. Hybridized to Illumina Sentrix Mouse-6 v1.1 Beadhips.
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappaB, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: differential gene expression; time course; innate immunity; pneumonia; immunocompromised host; lung epithelium Gene expression patterns in mouse lung homogenates were analyzed 2h after exposure to aerosolized PBS (Sham treatment), 2h after exposure to aerosolized NTHi lysate or 4h after exposure to aerosolized NTHi lysate. Each group consisted of six mice.
Project description:Rationale: Patients in the intensive care unit (ICU) are frequently exposed to unnecessary antibiotics. Markers of the host response to infection may aid pneumonia diagnosis and avoid antibiotic-induced complications. Objective: To assess the host response to suspected bacterial pneumonia through assessment of alveolar neutrophilia and transcriptomic profiling of alveolar macrophages. Methods: We determined the test characteristics of BAL neutrophilia for the diagnosis of bacterial pneumonia in 3 cohorts of mechanically ventilated patients. In one cohort, we also isolated alveolar macrophages from BAL fluid and used the transcriptome to identify signatures of bacterial pneumonia. Finally, we developed a humanized mouse model of Pseudomonas aeruginosa pneumonia to determine if pathogen-specific signatures can be identified in human alveolar macrophages. Measurements and Main Results: BAL neutrophilia was highly sensitive for bacterial pneumonia in both the retrospective (N = 851) and validation cohorts (N = 76 and N = 79) with a negative predictive value of over 90% when BAL neutrophil percentage was less than 50%. A transcriptional signature of bacterial pneumonia was present in both resident and recruited macrophages. Gene signatures from both cell types identified patients with bacterial pneumonia with test characteristics similar to BAL neutrophilia. Conclusions: A BAL neutrophil percentage of less than 50% is highly sensitive for bacterial pneumonia. Informative transcriptomic signatures can be generated from BAL fluid obtained during routine clinical care in the ICU. The identification of novel host response biomarkers is a promising approach to aid the diagnosis and treatment of pneumonia.
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappaB, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: differential gene expression; time course; innate immunity; pneumonia; immunocompromised host; lung epithelium
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappa-B, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: Differential expression, innate immunity, pneumonia, immunocompromised host; lung epithelium, in vitro,
Project description:Neutrophils are critical in the host defense against Staphylococcus aureus, a major human pathogen. However, even in the setting of a robust neutrophil response, S. aureus can cause persistent infection. Here we demonstrate that S. aureus impairs neutrophil function by triggering the production of the anti-inflammatory metabolite, itaconate. The enzyme that synthesizes itaconate, Irg1, is selectively expressed in neutrophils during S. aureus pneumonia. Itaconate inhibits neutrophil glycolysis and oxidative burst, which impairs survival and bacterial killing. In a murine pneumonia model, neutrophil Irg1 expression protects critical lung cell populations from oxidative stress but compromises bacterial clearance. S. aureus is thus able to evade innate immune clearance by targeting neutrophil metabolism and inducing the production of the antiinflammatory metabolite itaconate.
Project description:Bacterial pneumonia is still a major cause of morbidity and mortality worldwide. One of the reasons for this may be the lack of accurate diagnostic tests that results in delayed identification of the causative agent and subsequent delay in initiating appropriate therapy. Therefore, there is an urgent need for new diagnostic tools for the rapid identification of the causative agent in bacterial pneumonia. Host biomarkers for early identification of etiology agents in bacterial pneumonia could assist in the development of those new diagnostic tools. The existing biomarkers such as procalcitonin and C-reactive protein for diagnosis of bacterial pneumonia are rather unspecific inflammatory markers and are not discriminatory between different infectious pathogens. In this regard, the objective of this study was the identification of host biomarkers which could distinguish pneumococcal pneumonia from staphylococcal pneumonia in an experimental murine infection model using RNA-Sequencing.
Project description:In response to stress, the p53 tumor suppressor induces arrest or apoptosis by transcriptionally regulating genes that mediate these processes. It has been proposed that the levels of p53 can influence the choice between these different outcomes, but the mechanisms involved are not clear. To gain mechanistic understanding of this p53-dependent cell fate decision, we generated a p53 inducible system that allowed tight regulation of p53 expression in human mammary epithelial cells. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Using microarray and chromatin immunoprecipitation analysis, we showed that low and high levels of p53 bind to and activate the same set of pro arrest and pro apoptotic target genes, induced to lower and higher levels, respectively. We propose that the cell fate decision between arrest and apoptosis in these cells is determined by a higher threshold required for p53 dependent apoptosis. We suggest that high level p53 activation is crucial in order to achieve maximum efficacy of p53 targeted cancer therapies.
Project description:After DNA damage, cells activate p53, a tumor suppressor gene, and select a cell fate (e.g., DNA repair, cell cycle arrest, or apoptosis). Recently, a p53 oscillatory behavior was observed following DNA damage. However, the relationship between this p53 oscillation and cell-fate selection is unclear. Here, we present a novel model of the DNA damage signaling pathway that includes p53 and whole cell cycle regulation and explore the relationship between p53 oscillation and cell fate selection. The simulation run without DNA damage qualitatively realized experimentally observed data from several cell cycle regulators, indicating that our model was biologically appropriate. Moreover, the comprehensive sensitivity analysis for the proposed model was implemented by changing the values of all kinetic parameters, which revealed that the cell cycle regulation system based on the proposed model has robustness on a fluctuation of reaction rate in each process. Simulations run with four different intensities of DNA damage, i.e. Low-damage, Medium-damage, High-damage, and Excess-damage, realized cell cycle arrest in all cases. Low-damage, Medium-damage, High-damage, and Excess-damage corresponded to the DNA damage caused by 100, 200, 400, and 800 J/m(2) doses of UV-irradiation, respectively, based on expression of p21, which plays a crucial role in cell cycle arrest. In simulations run with High-damage and Excess-damage, the length of the cell cycle arrest was shortened despite the severe DNA damage, and p53 began to oscillate. Cells initiated apoptosis and were killed at 400 and 800 J/m(2) doses of UV-irradiation, corresponding to High-damage and Excess-damage, respectively. Therefore, our model indicated that the oscillatory mode of p53 profoundly affects cell fate selection.