Age-independent co-expression of antimicrobial gene clusters in the blood of septic patients

Recent research has unravelled the clinical potential of profiling the blood transcriptome to diagnose diseases. However, resulting molecular marker sets comprised features with varying robustness and performance, depending on the dimension of training data. Thus, we investigated patterns that are inherent in large-scale data and suitable for feature selection in application to blood samples from septic patients. By integrating >300 microarray samples in correlation and enrichment analysis, we found general response patterns including a vast majority of co-expressed genes. Differentially expressed genes significantly mapped to immune response-associated categories and revealed strongly correlating upregulated genes related to antimicrobial functions. Classifiers using >20 uncorrelated features from enriched functional categories performed with 85% correct classification on average (10-fold cross-validation), comparable with correlated features, whilst single genes achieved up to 83% correct classifications in identifying septic patients. Independent interplatform comparison, however, validated only a subset of these features, including the antimicrobial cluster (area under the receiver operating characteristic curve >0.8). Based on these results, we propose feature selection for classification incorporating correlation and enriched functional categories to obtain robust marker candidates. Results of this transcriptomic meta-analysis suggest age-independent diagnostic opportunities, although further observational and animal interventional experiments are required to confirm the relevance of antimicrobial genes in sepsis

Simvastatin pre-treatment improves survival and mitochondrial function in a 3-day fluid-resuscitated rat model of sepsis

Statins may offer protective effects in sepsis through anti-inflammatory, mitochondrial protection and other actions. We thus evaluated the effects of simvastatin on survival, organ and mitochondrial function, tissue and plasma ubiquinone levels and liver transcriptomics in a 3-day rat model of sepsis. Comparisons of rat plasma simvastatin and ubiquinone levels were made against levels sampled in blood from patients with acute lung injury (ALI) enrolled into a trial of statin therapy. Animals received simvastatin by gavage either pre-or post-induction of faecal peritonitis. Control septic animals received vehicle alone. Seventy-two-hour survival was significantly greater in statin pre-treated animals (43.7%) compared with their statin post-treated (12.5%) and control septic (25%) counterparts (P < 0.05). Sepsis-induced biochemical derangements in liver and kidney improved with statin therapy, particularly when given pre-insult. Both simvastatin pre-and post-treatment prevented the fall in mitochondrial oxygen consumption in muscle fibres taken from septic animals at 24 h. This beneficial effect was paralleled by recovery of genes related to fatty acid metabolism. Simvastatin pre-treatment resulted in a significant decrease in myocardial ubiquinone. Patients with ALI had a marked variation in plasma simvastatin acid levels; however, their ubiquinone/low-density lipoprotein (LDL) cholesterol ratio did not differ regardless of whether they were receiving statin or placebo. In summary, despite protective effects seen with statin treatment given both pre-and post-insult, survival benefit was only seen with pre-treatment, reflecting experiences in patient studies

Improvement of prognostic performance in severely injured patients by integrated clinico-transcriptomics: a translational approach

INTRODUCTION Severe trauma triggers a systemic inflammatory response that contributes to secondary complications, such as nosocomial infections, sepsis or multi-organ failure. The present study was aimed to identify markers predicting complications and an adverse outcome of severely injured patients by an integrated clinico-transcriptomic approach. METHODS In a prospective study, RNA samples from circulating leukocytes from severely injured patients (injury severity score ≥ 17 points; n = 104) admitted to a Level I Trauma Center were analyzed for dynamic changes in gene expression over a period of 21 days by quantitative RT-PCR. Transcriptomic candidates were selected based on whole genome screening of a representative discovery set (n = 10 patients) or known mechanisms of the immune response, including mediators of inflammation (IL-8, IL-10, TNF-α, MIF, C5, CD59, SPHK1), danger signaling (HMGB1, TLR2, CD14, IL-33, IL-1RL1), and components of the heme degradation pathway (HP, CD163, HMOX1, BLVRA, BLVRB). Clinical markers comprised standard physiological and laboratory parameters and scoring systems routinely determined in trauma patients. RESULTS Leukocytes, thrombocytes and the expression of sphingosine kinase-1 (SPHK1), complement C5, and haptoglobin (HP) have been identified as markers with the best performance. Leukocytes showed a biphasic course with peaks on day 0 and day 11 after trauma, and patients with sepsis exhibited significantly higher leukocyte levels. Thrombocyte numbers showed a typical profile with initial thrombopenia and robust thrombocytosis in week 3 after trauma, ranging 2- to 3-fold above the upper normal value. 'Relative thrombocytopenia' was associated with multi-organ dysfunction, the development of sepsis, and mortality, the latter of which could be predicted within 3 days prior to the time point of death. SPHK1 expression at the day of admission indicated mortality with excellent performance. C5-expression on day 1 after trauma correlated with an increased risk for the development of nosocomial infections during the later course, while HP was found to be a marker for the development of sepsis. CONCLUSIONS The combination of clinical and transcriptomic markers improves the prognostic performance and may represent a useful tool for individual risk stratification in trauma patients

Metabolic Adaptation Establishes Disease Tolerance to Sepsis

International audienceSepsis is an often lethal syndrome resulting from maladaptive immune and metabolic responses to infection, compromising host homeostasis. Disease tolerance is a defense strategy against infection that preserves host homeostasis without exerting a direct negative impact on pathogens. Here, we demonstrate that induction of the iron-sequestering ferritin H chain (FTH) in response to polymicrobial infections is critical to establish disease tolerance to sepsis. The protective effect of FTH is exerted via a mechanism that counters iron-driven oxidative inhibition of the liver glucose-6-phosphatase (G6Pase), and in doing so, sustains endogenous glucose production via liver gluconeogenesis. This is required to prevent the development of hypoglycemia that otherwise compromises disease tolerance to sepsis. FTH overexpression or ferritin administration establish disease tolerance therapeutically. In conclusion, disease tolerance to sepsis relies on a crosstalk between adaptive responses controlling iron and glucose metabolism, required to maintain blood glucose within a physiologic range compatible with host survival

Streptococcus pneumoniae triggers progression of pulmonary fibrosis through pneumolysin

Rationale: Respiratory tract infections are common in patients suffering from pulmonary fibrosis. The interplay between bacterial infection and fibrosis is characterised poorly. Objectives: To assess the effect of Gram-positive bacterial infection on fibrosis exacerbation in mice. Methods Fibrosis progression in response to Streptococcus pneumoniae was examined in two different mouse models of pulmonary fibrosis. Measurements and main results: We demonstrate that wild-type mice exposed to adenoviral vector delivery of active transforming growth factor-beta 1 (TGF beta 1) or diphteria toxin (DT) treatment of transgenic mice expressing the DT receptor (DTR) under control of the surfactant protein C (SPC) promoter (SPC-DTR) to induce pulmonary fibrosis developed progressive fibrosis following infection with Spn, without exhibiting impaired lung protective immunity against Spn. Antibiotic treatment abolished infection-induced fibrosis progression. The cytotoxin pneumolysin (Ply) of Spn caused this phenomenon in a TLR4-independent manner, as Spn lacking Ply (Spn Delta ply) failed to trigger progressive fibrogenesis, whereas purified recombinant Ply did. Progressive fibrogenesis was also observed in AdTGF beta 1-exposed Ply-challenged TLR4 KO mice. Increased apoptotic cell death of alveolar epithelial cells along with an attenuated intrapulmonary release of antifibrogenic prostaglandin E2 was found to underlie progressive fibrogenesis in Ply-challenged AdTGF beta 1-exposed mice. Importantly, vaccination of mice with the non-cytotoxic Ply derivative B (PdB) substantially attenuated Ply-induced progression of lung fibrosis in AdTGF beta 1-exposed mice. Conclusions: Our data unravel a novel mechanism by which infection with Spn through Ply release induces progression of established lung fibrosis, which can be attenuated by protein-based vaccination of mice

Additional file 1: Table S1. of Improvement of prognostic performance in severely injured patients by integrated clinico-transcriptomics: a translational approach

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Data_Sheet_1_Modeling Hemolytic-Uremic Syndrome: In-Depth Characterization of Distinct Murine Models Reflecting Different Features of Human Disease.PDF

<p>Diarrhea-positive hemolytic-uremic syndrome (HUS) is a renal disorder that results from infections with Shiga-toxin (Stx)-producing Escherichia coli. The aim of this study was to establish well-defined refined murine models of HUS that can serve as preclinical tools to elucidate molecular mechanisms of disease development. C57BL/6J mice were subjected to different doses of Stx2 purified from an E. coli O157:H7 patient isolate. Animals received 300 ng/kg Stx2 and were sacrificed on day 3 to establish an acute model with fast disease progression. Alternatively, mice received 25 ng/kg Stx2 on days 0, 3, and 6, and were sacrificed on day 7 to establish a subacute model with moderate disease progression. Indicated by a rise in hematocrit, we observed dehydration despite volume substitution in both models, which was less pronounced in mice that underwent the 7-day regime. Compared with sham-treated animals, mice subjected to Stx2 developed profound weight loss, kidney dysfunction (elevation of plasma urea, creatinine, and neutrophil gelatinase-associated lipocalin), kidney injury (tubular injury and loss of endothelial cells), thrombotic microangiopathy (arteriolar microthrombi), and hemolysis (elevation of plasma bilirubin, lactate dehydrogenase, and free hemoglobin). The degree of complement activation (C3c deposition), immune cell invasion (macrophages and T lymphocytes), apoptosis, and proliferation were significantly increased in kidneys of mice subjected to the 7-day but not in kidneys of mice subjected to the 3-day regime. However, glomerular and kidney volume remained mainly unchanged, as assessed by 3D analysis of whole mount kidneys using CD31 staining with light sheet fluorescence microscopy. Gene expression analysis of kidneys revealed a total of only 91 overlapping genes altered in both Stx2 models. In conclusion, we have developed two refined mouse models with different disease progression, both leading to hemolysis, thrombotic microangiopathy, and acute kidney dysfunction and damage as key clinical features of human HUS. While intrarenal changes (apoptosis, proliferation, complement deposition, and immune cell invasion) mainly contribute to the pathophysiology of the subacute model, prerenal pathomechanisms (hypovolemia) play a predominant role in the acute model. Both models allow the further study of the pathomechanisms of most aspects of human HUS and the testing of distinct novel treatment strategies.</p

Video_1_Modeling Hemolytic-Uremic Syndrome: In-Depth Characterization of Distinct Murine Models Reflecting Different Features of Human Disease.mp4

<p>Diarrhea-positive hemolytic-uremic syndrome (HUS) is a renal disorder that results from infections with Shiga-toxin (Stx)-producing Escherichia coli. The aim of this study was to establish well-defined refined murine models of HUS that can serve as preclinical tools to elucidate molecular mechanisms of disease development. C57BL/6J mice were subjected to different doses of Stx2 purified from an E. coli O157:H7 patient isolate. Animals received 300 ng/kg Stx2 and were sacrificed on day 3 to establish an acute model with fast disease progression. Alternatively, mice received 25 ng/kg Stx2 on days 0, 3, and 6, and were sacrificed on day 7 to establish a subacute model with moderate disease progression. Indicated by a rise in hematocrit, we observed dehydration despite volume substitution in both models, which was less pronounced in mice that underwent the 7-day regime. Compared with sham-treated animals, mice subjected to Stx2 developed profound weight loss, kidney dysfunction (elevation of plasma urea, creatinine, and neutrophil gelatinase-associated lipocalin), kidney injury (tubular injury and loss of endothelial cells), thrombotic microangiopathy (arteriolar microthrombi), and hemolysis (elevation of plasma bilirubin, lactate dehydrogenase, and free hemoglobin). The degree of complement activation (C3c deposition), immune cell invasion (macrophages and T lymphocytes), apoptosis, and proliferation were significantly increased in kidneys of mice subjected to the 7-day but not in kidneys of mice subjected to the 3-day regime. However, glomerular and kidney volume remained mainly unchanged, as assessed by 3D analysis of whole mount kidneys using CD31 staining with light sheet fluorescence microscopy. Gene expression analysis of kidneys revealed a total of only 91 overlapping genes altered in both Stx2 models. In conclusion, we have developed two refined mouse models with different disease progression, both leading to hemolysis, thrombotic microangiopathy, and acute kidney dysfunction and damage as key clinical features of human HUS. While intrarenal changes (apoptosis, proliferation, complement deposition, and immune cell invasion) mainly contribute to the pathophysiology of the subacute model, prerenal pathomechanisms (hypovolemia) play a predominant role in the acute model. Both models allow the further study of the pathomechanisms of most aspects of human HUS and the testing of distinct novel treatment strategies.</p