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Plasticity of the systemic inflammatory response to acute infection during critical illness: development of the riboleukogram.

ABSTRACT: Diagnosis of acute infection in the critically ill remains a challenge. We hypothesized that circulating leukocyte transcriptional profiles can be used to monitor the host response to and recovery from infection complicating critical illness.A translational research approach was employed. Fifteen mice underwent intratracheal 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 27 mechanically ventilated patients every two days for up to three weeks. Significant heterogeneity of VAP microarray profiles was observed secondary to patient ethnicity, age, and gender, yet 85 genes were identified with consistent changes in abundance during the seven days bracketing the diagnosis of VAP. Principal components analysis of these 85 genes appeared to differentiate between the responses of subjects who did versus those who did not develop VAP, as defined by a general trajectory (riboleukogram) for the onset and resolution of VAP. As patients recovered from critical illness complicated by acute infection, the riboleukograms converged, consistent with an immune attractor.Here we present the culmination of a mouse pneumonia study, demonstrating for the first time that disease trajectories derived from microarray expression profiles can be used to quantitatively track the clinical course of acute disease and identify a state of immune recovery. These data suggest that the onset of an infection-specific transcriptional program may precede the clinical diagnosis of pneumonia in patients. Moreover, riboleukograms may help explain variance in the host response due to differences in ethnic background, gender, and pathogen. Prospective clinical trials are indicated to validate our results and test the clinical utility of riboleukograms.

SUBMITTER: McDunn JE

PROVIDER: S-EPMC2215774 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature

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Plasticity of the systemic inflammatory response to acute infection during critical illness: development of the riboleukogram.

McDunn Jonathan E JE Husain Kareem D KD Polpitiya Ashoka D AD Burykin Anton A Ruan Jianhua J Li Qing Q Schierding William W Lin Nan N Dixon David D Zhang Weixiong W Coopersmith Craig M CM Dunne W Michael WM Colonna Marco M Ghosh Bijoy K BK Cobb J Perren JP

PloS one 20080213 2

<h4>Background</h4>Diagnosis of acute infection in the critically ill remains a challenge. We hypothesized that circulating leukocyte transcriptional profiles can be used to monitor the host response to and recovery from infection complicating critical illness.<h4>Methodology/principal findings</h4>A translational research approach was employed. Fifteen mice underwent intratracheal injections of live P. aeruginosa, P. aeruginosa endotoxin, live S. pneumoniae, or normal saline. At 24 hours after ...[more]

PMID: 18270561

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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:BackgroundHigh-altitude cerebral edema (HACE) is the severe type of acute mountain sickness (AMS) and life threatening. A subclinical inflammation has been speculated, but the exact mechanisms underlying the HACE are not fully understood.MethodsHuman volunteers ascended to high altitude (3860 m, 2 days), and rats were exposed to hypoxia in a hypobaric chamber (5000 m, 2 days). Human acute mountain sickness was evaluated by the Lake Louise Score (LLS), and plasma corticotrophin-releasing hormone (CRH) and cytokines TNF-α, IL-1β, and IL-6 were measured in rats and humans. Subsequently, rats were pre-treated with lipopolysaccharide (LPS, intraperitoneal (ip) 4 mg/kg, 11 h) to induce inflammation prior to 1 h hypoxia (7000 m elevation). TNF-α, IL-1β, IL-6, nitric oxide (NO), CRH, and aquaporin-4 (AQP4) and their gene expression, Evans blue, Na(+)-K(+)-ATPase activity, p65 translocation, and cell swelling were measured in brain by ELISA, Western blotting, Q-PCR, RT-PCR, immunohistochemistry, and transmission electron micrography. MAPKs, NF-κB pathway, and water permeability of primary astrocytes were demonstrated. All measurements were performed with or without LPS challenge. The release of NO, TNF-α, and IL-6 in cultured primary microglia by CRH stimulation with or without PDTC (NF-κB inhibitor) or CP154,526 (CRHR1 antagonist) were measured.ResultsHypobaric hypoxia enhanced plasma TNF-α, IL-1β, and IL-6 and CRH levels in human and rats, which positively correlated with AMS. A single LPS injection (ip, 4 mg/kg, 12 h) into rats increased TNF-α and IL-1β levels in the serum and cortex, and AQP4 and AQP4 mRNA expression in cortex and astrocytes, and astrocyte water permeability but did not cause brain edema. However, LPS treatment 11 h prior to 1 h hypoxia (elevation, 7000 m) challenge caused cerebral edema, which was associated with activation of NF-κB and MAPKs, hypoxia-reduced Na(+)-K(+)-ATPase activity and blood-brain barrier (BBB) disruption. Both LPS and CRH stimulated TNF-α, IL-6, and NO release in cultured rat microglia via NF-κB and cAMP/PKA.ConclusionsPreexisting systemic inflammation plus a short severe hypoxia elicits cerebral edema through upregulated AQP4 and water permeability by TLR4 and CRH/CRHR1 signaling. This study revealed that both infection and hypoxia can cause inflammatory response in the brain. Systemic inflammation can facilitate onset of hypoxic cerebral edema through interaction of astrocyte and microglia by activation of TLR4 and CRH/CRHR1 signaling. Anti-inflammatory agents and CRHR1 antagonist may be useful for prevention and treatment of AMS and HACE.

Dataset Information

Plasticity of the systemic inflammatory response to acute infection during critical illness: development of the riboleukogram.

Publications

Plasticity of the systemic inflammatory response to acute infection during critical illness: development of the riboleukogram.

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