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The Monocyte Advantage

ABSTRACT: INTRO: The ongoing challenge of accurately diagnosing infection in the ICU motivates a search for novel molecular diagnostics. In the current study, we tested the hypothesis that the informational content of circulating leukocytes differs, thereby allowing one to rank leukocyte populations on their potential to contribute to RNA diagnostics for pneumonia. METHODS: Sixteen patients (10 male, 6 female) at risk for VAP were entered into our IRB-approved study that collects blood and clinical data every 48 hours for up to 21 days. Four of the sixteen patients developed VAP as diagnosed and treated by the attending ICU physician. Previously reported blood protocols were used to isolate buffy coat, enriched neutrophil, and enriched monocyte populations by using negative selection. Cellular purity was assessed by FACS for one of the 4 VAP patients. Genome-wide expression analysis was performed on RMA-normalized signal from Affymetrix U133 2.0 Plus GeneChips. EDGE software (FDR=0.10) was used to determine changes in mRNA abundance over time for each cell population. RESULTS: During the 5-day window in which each of the four patients (all males) developed VAP, significant changes in gene expression were observed (Table 2), but the information content (number of genes altered) varied across leukocyte populations. These differences were not due to signal variance (coefficient of variation, CV) or differences in the number of samples available for analysis. Moreover, only 0.6% of the monocyte gene list overlaps with the neutrophil list, arguing that neutrophil contamination of monocyte populations is insufficient to explain the 40-fold difference in gene number. CONCLUSIONS: Enriched monocyte populations from circulating blood provide far more genes for study of the host response to VAP than the other 2 cell populations studied. This information should be considered when designing blood gene expression profiling experiments in patients at risk for sepsis. Keywords: time course

ORGANISM(S): Homo sapiens

PROVIDER: GSE12838 | GEO | 2010/09/09

SECONDARY ACCESSION(S): PRJNA112539

REPOSITORIES: GEO

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Project description:INTRO: The ongoing challenge of accurately diagnosing infection in the ICU motivates a search for novel molecular diagnostics. In the current study, we tested the hypothesis that the informational content of circulating leukocytes differs, thereby allowing one to rank leukocyte populations on their potential to contribute to RNA diagnostics for pneumonia. METHODS: Sixteen patients (10 male, 6 female) at risk for VAP were entered into our IRB-approved study that collects blood and clinical data every 48 hours for up to 21 days. Four of the sixteen patients developed VAP as diagnosed and treated by the attending ICU physician. Previously reported blood protocols were used to isolate buffy coat, enriched neutrophil, and enriched monocyte populations by using negative selection. Cellular purity was assessed by FACS for one of the 4 VAP patients. Genome-wide expression analysis was performed on RMA-normalized signal from Affymetrix U133 2.0 Plus GeneChips. EDGE software (FDR=0.10) was used to determine changes in mRNA abundance over time for each cell population. RESULTS: During the 5-day window in which each of the four patients (all males) developed VAP, significant changes in gene expression were observed (Table 2), but the information content (number of genes altered) varied across leukocyte populations. These differences were not due to signal variance (coefficient of variation, CV) or differences in the number of samples available for analysis. Moreover, only 0.6% of the monocyte gene list overlaps with the neutrophil list, arguing that neutrophil contamination of monocyte populations is insufficient to explain the 40-fold difference in gene number. CONCLUSIONS: Enriched monocyte populations from circulating blood provide far more genes for study of the host response to VAP than the other 2 cell populations studied. This information should be considered when designing blood gene expression profiling experiments in patients at risk for sepsis. Keywords: time course Four patients over several timepoints measured three different cell types for VAP signal

Project description:Abstract BACKGROUND: Gene expression profiling (GEP) in cells obtained from peripheral blood has demonstrated to be a very useful approach for biomarker discovery and for studying molecular pathogenesis of prevalent diseases. While there is limited literature availble on gene expression markers associated to Chronic Obstructive Pulmonary Disease (COPD), the transcriptomic picture associated to critical respiratory illness in this disease is not known to the present moment. RESULTS: By using Agilent microarray chips, we have profiled gene expression signatures in whole blood of 28 COPD patients hospitalized with distinct degree of respiratory compromise.12 of them needed of admission to the ICU, while 16 were admitted to the Respiratory Medicine Service. GeneSpring GX 11.0 software was used for performing statistical comparison of transcript levels between ICU and non ICU patients. Ingenuity pathway analysis 8.5 (IPA) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were employed to select, annotate and visualize genes by function and pathway (gene ontology). T-test evidenced 1501 genes differentially expressed between ICU and non ICU patients. IPA and KEGG analysis of the most representative biological functions revealed that ICU patients showed increased levels of neutrohil gene transcripts, being [cathepsin G (CTSG)], [elastase, neutrophil expressed (ELANE)], [proteinase 3 (PRTN3)], [myeloperoxidase (MPO)], [cathepsin D (CTSD)], [defensin, alpha 3, neutrophil-specific (DEFA3)], azurocidin 1 (AZU1)], [bactericidal/permeability-increasing protein (BPI)] the most representative ones. Proteins codified by these genes form part of the azurophilic granules of neutrophils and are involved in both antimicrobial defence and tissue damage. This ?neutrophil signature? was paralleled by necessity of advanced respiratory and vital support, and presence of bacterial infection. CONCLUSION: study of transcriptomic signatures in blood suggests a central role of neutrophil proteases in COPD patients with critical respiratory illness. Measurement / modulation of the expression of these genes could represent an option for clinical monitoring and treatment of severe COPD exacerbations. Keywords: COPD, critical, expression, gene, microarray, neutrophil, proteases.

Project description:Diagnosis of acute infection in the critically ill remains a challenge. Changes in physiologic parameters and existing molecular diagnostics are not specific and microbiologic confirmation of infection can take days. As cellular first responders, preclinical studies indicate that circulating leukocytes are activated in response to bacterial infection, manifesting infection-specific transcriptional programs. We hypothesized that circulating leukocyte transcriptional profiles can be used to diagnose infection and monitor response to therapy in the critically ill. Experiment Overall Design: A translational research approach was employed. Fifteen mice underwent intratracheal (i.t.) injections of live P. aeruginosa, P. aeruginosa endotoxin, live S. pneumoniae, or normal saline. At 24 hours after injury, GeneChip microarray analysis of circulating buffy coat RNA identified 219 genes that distinguished between the pulmonary insults and differences in 7-day mortality. Similarly, buffy coat microarray expression profiles were generated from 20 mechanically ventilated patients every two days for up to three weeks; 11 of these patients developed pneumonia. Principal components analysis of the expression levels of the human orthologs for the mouse genes resulted in gene expression trajectories that describe the cohort of 11 patients as they develop, are treated for, and convalesce from ventilator-associated pneumonia (VAP). When the VAP microarray profiles were analyzed independently, 85 genes were identified with consistent changes in abundance during the seven days bracketing the diagnosis of VAP. The estimated prediction accuracy in this small patient cohort was 91%. The abundance of select transcripts was validated using real-time PCR. Principal components analysis of the average microarray-measured abundances of these genes defined a general trajectory (riboleukogram) for the onset of acute infection in this patient population. Individual riboleukograms demonstrated that the onset and course of infection are specific for each individual, but as patients recover from infection the riboleukograms converge. The gene ontologies of the co-expression networks indicate that leukocyte chemokines and granule maturation are especially informative for pneumonia diagnostics.

Project description:Monitoring genome-wide, cell-specific responses to human disease, although challenging, holds great promise for medicineâs future. Patients with injury severe enough to develop multiple organ dysfunction syndrome (MODS) are known to have multiple immune derangements, including T-cell apoptosis and anergy combined with depressed monocyte antigen presentation. Genome-wide expression analysis of highly-enriched circulating leukocyte subpopulations, combined with cell-specific pathway analyses, offers a previously unavailable opportunity to discover novel leukocyte regulatory networks in critically injured patients. Severe injury induced significant changes in the T-cell, monocyte, and total leukocyte transcriptome, with only 12% of these genomic changes common to all three cell populations. T-cell-specific pathway analyses identified increased gene expression of several novel inhibitory receptors (PD-1, CD152, NRP-1, Lag3), and concomitant decreases in stimulatory receptors (CD28, CD4, IL-2Rï¡). Functional analysis of T-cells and monocytes confirmed reduced T-cell proliferation and increased cell surface expression of negative signaling receptors paired with decreased monocyte costimulation ligands. Thus, genome-wide expression from highly-enriched cell populations combined with knowledge-based pathway analyses leads to the identification of novel regulatory networks differentially expressed in injured patients. Importantly, application of cell separation, genome-wide expression, and cell specific pathway analyses can be used to discover novel pathway alterations in human disease. Experiment Overall Design: Type of experiment: Gene expression profiling of circulating total blood Experiment Overall Design: leukocytes, T-Cells, and Monocytes in severe trauma patients and healthy subjects. Experiment Overall Design: Experimental factors: Healthy subjects, 7 severely traumatized patients Experiment Overall Design: and 7 healthy subjects for transcriptome analysis. Venous blood samples Experiment Overall Design: were collected. Total blood leukocytes were isolated, and T-cell and Experiment Overall Design: monocyte populations were obtained from two subsequent aliquots of the Experiment Overall Design: leukocytes. Total leukocytes, enriched T-cells, and enriched monocytes were analyzed using Affymetrix GeneChip arrays. Experiment Overall Design: Number of hybridizations: 42 Human U133A GeneChip arrays (Affymetrix)

Project description:Objective: COVID19 is caused by the SARS-CoV-2 virus and has been associated with severe inflammation leading to organ dysfunction and mortality. Our aim was to profile the transcriptome in leukocytes from critically ill ICU patients positive for COVID19 vs. those negative for COVID19 to better understand the COVID19 associated host response. Design: Transcriptome profiling of buffy coat cells via ribonucleic acid sequencing (RNAseq) at the time of admission to the ICU. Setting: Tertiary care ICU and academic laboratory. Subjects: All patients admitted to the ICU suspected of being infected with SARS-CoV-2, using standardized hospital screening methodologies, had blood samples collected at the time of admission to the ICU. Interventions: None. Measurement and Main Results: Age- and sex-matched ICU patients that were either COVID19+ (PCR positive, 2 genes) or COVID19- (PCR negative) were enrolled. Cohorts were well-balanced with the exception that COVID19- patients had significantly higher total white blood cell counts and circulating neutrophils and COVID19+ patients were more likely to suffer bilateral pneumonia compared to COVID19- patients. Further, the mortality rate for this cohort of COVID19+ ICU patients was 29%. Transcriptional analysis revealed that when compared to COVID19- patients, the altered transcriptional responses of leukocytes in critically ill COVID19+ ICU patients appeared to be associated with multiple interrelated outcomes, including but not limited to robust interferon (IFN)-associated transcriptional responses, a marked decrease in the transcriptional activity of genes contributing to protein synthesis and the dysregulated expression of genes that contribute to coagulation, platelet activation, Toll-like receptor activation, neurotrophin signaling, and protein SUMOylation/ubiquitination. Conclusions: COVID19+ patients on day 1 of admission to the ICU display a unique leukocyte transcriptional profile that distinguishes them from COVID19- patients. Identification of this profile provides guidance for future targeted studies exploring novel prognostic/therapeutic aspects of COVID19.

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The Monocyte Advantage

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