Failure to recover somatotropic axis function is associated with mortality from pediatric sepsis-induced multiple organ dysfunction syndrome.

OBJECTIVES: To describe the associations between mediators of the somatotropic axis and mortality from sepsis-induced multiple organ dysfunction syndrome in children; and to examine the relationship between immune function and the somatotropic axis in this setting. DESIGN: Retrospective study using banked plasma. SETTING: Single mixed surgical/medical intensive care unit at a quaternary level children's hospital. PATIENTS: A total of 24 children (n = 17 survivors, 7 nonsurvivors) with severe sepsis or septic shock and dysfunction of >or=2 organ systems. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma samples were available from days 3, 7, and 14 of multiple organ dysfunction syndrome. Insulin-like growth factor 1 and insulin-like growth factor binding protein 3 levels were measured by chemiluminescence. Immune function was quantified using previously determined ex vivo lipopolysaccharide-induced tumor necrosis factor-alpha production levels and absolute lymphocyte counts. Insulin-like growth factor 1 levels were lower in nonsurvivors compared with survivors (p = .004) with the greatest difference seen on day 14 (25 [25-69] ng/mL vs. 314 [123-582] ng/mL; p = .038). insulin-like growth factor binding protein 3 levels were reduced similarly over time (p = .019). A drop in plasma insulin-like growth factor binding protein 3 level at any time after day 3 of illness resulted in a 35-fold increased odds of death (odds ratio, 35 [1.6-750]; p = .004). Both ex vivo tumor necrosis factor-alpha and absolute lymphocyte count were reduced in nonsurvivors compared with survivors, but these differences occurred earlier (days 3 and 7). CONCLUSIONS: These data suggest that prolonged reduction of somatotropic axis function is associated with mortality from pediatric sepsis-induced multiple organ dysfunction syndrome. Reductions in innate and adaptive immune function are common in this population and are associated with failure of recovery of the somatotropic axis, although the nature of these relationships remains incompletely understood.

Inflammasome mRNA expression in human monocytes during early septic shock.

RATIONALE: Monocytes are central to the initiation of the inflammatory response in sepsis, with caspase-1 activation playing a key role. Monocyte deactivation during sepsis has been linked to poor outcomes. OBJECTIVES: Given the importance of caspase-1 in the immune response, we investigated whether monocytes from patients early in septic shock demonstrate alterations in mRNAs for caspase-1-related molecules. METHODS: Patients with septic shock (n = 26; age >18 years), critically ill intensive care unit patients (n = 20), and healthy volunteers (n = 22) were enrolled in a prospective cohort study in a university intensive care unit. Demographic, biological, physiologic, and plasma cytokine measurements were obtained. Monocytes were assayed for ex vivo tumor necrosis factor-alpha production, and fresh monocyte mRNA was analyzed by quantitative reverse-transcription polymerase chain reaction for Toll-like receptors, NOD-LRR proteins, cytokines, and nuclear factor-kappaB-related genes. MEASUREMENTS AND MAIN RESULTS: Relative copy numbers for the inflammasome mRNAs for ASC, caspase-1, NALP1, and Pypaf-7 were significantly lower in patients with septic shock compared with critically ill control subjects. NALP1 mRNA levels were linked to survival in patients with sepsis (P = 0.0068) and correlated with SAPS II scores (r = -0.63). CONCLUSIONS: These data suggest that monocyte deactivation occurs during the earliest stages of the systemic inflammatory response and that changes in inflammasome mRNA expression are part of this process.

Immunoparalysis and nosocomial infection in children with multiple organ dysfunction syndrome.

PURPOSE: Immunoparalysis defined by prolonged monocyte human leukocyte antigen DR depression is associated with adverse outcomes in adult severe sepsis and can be reversed with granulocyte macrophage colony-stimulating factor (GM-CSF). We hypothesized that immunoparalysis defined by whole-blood ex vivo lipopolysaccharide-induced tumor necrosis factor-alpha (TNFα) response <200 pg/mL beyond day 3 of multiple organ dysfunction syndrome (MODS) is similarly associated with nosocomial infection in children and can be reversed with GM-CSF. METHODS: In study period 1, we performed a multicenter cohort trial of transplant and nontransplant multiple organ dysfunction syndrome (MODS) patients (≥2 organ failure). In study period 2, we performed an open-label randomized trial of GM-CSF therapy for nonneutropenic, nontransplant, severe MODS patients (≥3 organ failure) with TNFα response <160 pg/mL. RESULTS: Immunoparalysis was observed in 34% of MODS patients (n = 70) and was associated with increased nosocomial infection (relative risk [RR] 3.3, 95% confidence interval [1.8-6.0] p < 0.05) and mortality (RR 5.8 [2.1-16] p < 0.05). TNFα response <200 pg/mL throughout 7 days after positive culture was associated with persistent nosocomial infection, whereas recovery above 200 pg/mL was associated with resolution of infection (p < 0.05). In study period 2, GM-CSF therapy facilitated rapid recovery of TNFα response to >200 pg/mL by 7 days (p < 0.05) and prevented nosocomial infection (no infections in seven patients versus eight infections in seven patients) (p < 0.05). CONCLUSIONS: Similar to in adults, immunoparalysis is a potentially reversible risk factor for development of nosocomial infection in pediatric MODS. Whole-blood ex vivo TNFα response is a promising biomarker for monitoring this condition.

Timing of correct parenteral antibiotic initiation and outcomes from severe bacterial community-acquired pneumonia in children.

BACKGROUND: The impact of timing of appropriate antibiotic initiation for critically ill children with severe bacterial community-acquired pneumonia (CAP) is unknown. We hypothesized that longer time to initiation of correct parenteral antibiotic would be associated with longer durations of mechanical ventilation, intensive care unit length of stay, and hospital length of stay. METHODS: We retrospectively reviewed medical records of children admitted to Nationwide Children's Hospital between January 2004 and December 2006 with bacterial CAP treated with mechanical ventilation, excluding those with documented viral infection. Time to correct antibiotic was defined as time from presentation to any emergency department to the initiation of a parenteral antibiotic to which cultured pathogens were susceptible. RESULTS: In all, 45 patients, median age 17 months, were identified. Median time to correct antibiotic was 10.3 hours, with 71% of patients receiving correct empiric therapy. After adjusting for severity of illness, longer time to correct antibiotic was independently associated with longer hospital stay (P = 0.007). For the 23 patients in the cohort for whom pneumonia was the primary diagnosis, longer time to correct antibiotic was independently associated with longer durations of mechanical ventilation (P = 0.01), intensive care unit stay (P = 0.001), and hospital stay (P = 0.006). Delays in antibiotic administration as short as 2 to 4 hours were associated with adverse outcomes in this group. CONCLUSIONS: In our critically ill children with severe bacterial CAP, longer delays in receipt of appropriate empiric antibiotics were independently associated with adverse outcomes.

Monocyte mRNA phenotype and adverse outcomes from pediatric multiple organ dysfunction syndrome.

Impairment of the ability to mount an inflammatory response is associated with death from adult critical illness. This phenomenon, characterized by reduced monocyte production of proinflammatory mediators such as tumor necrosis factor alpha (TNF-alpha), is poorly understood in children. We hypothesized that differential expression of inflammation-related genes would be seen in monocytes from children with adverse outcomes from multiple organ dysfunction syndrome (MODS). Ex vivo lipopolysaccharide (LPS)-induced TNF-alpha production and plasma cytokines were prospectively measured biweekly in children with dysfunction of two or more organs. Concomitantly, monocyte expression of 28 pro- and anti-inflammatory genes [cytokines, Toll-like receptor (TLR)/nuclear factor kappaB (NF-kappaB) signaling pathway members, inflammasome elements] was measured. Thirty children (22 survivors, eight nonsurvivors) were evaluated. High mRNA levels for interleukin (IL)-10, IL-1 receptor-associated kinase (IRAK-M), and the putative inflammasome inhibitor pyrin were associated with death (p < or = 0.02). Plasma IL-10 levels were higher and ex vivo TNF-alpha production was lower in nonsurvivors (p < 0.05). Among survivors, high mRNA levels for IL-10, IRAK-M, pyrin, IRAK1, or TLR4 were associated with longer durations of pediatric intensive care unit (PICU) stay and mechanical ventilation (p < or = 0.02). These data suggest that adverse outcomes from pediatric MODS are associated with an anti-inflammatory monocyte mRNA phenotype. Future studies are warranted to explore mechanisms of immunodepression in pediatric critical illness.

Internalization and phagosome escape required for Francisella to induce human monocyte IL-1beta processing and release.

Macrophage responses to Francisella infection have been characterized previously by subdued proinflammatory responses; however, these studies have generally focused on macrophage cell lines or monocyte-derived macrophages. Therefore, we studied the ability of fresh human blood monocytes to engulf and respond to Francisella by using the live vaccine strain variant and Francisella novicida. Because Francisella organisms have been reported to escape from the phagolysosome into the cytosol, we hypothesized that this escape may trigger the activation of caspase-1. Francisella tularensis variants were readily taken up by fresh human CD14(+) monocytes, inducing the release of IL-1beta, as well as IL-8, in a time- and dose-dependent fashion. Importantly, whereas live and dead Escherichia coli, F. novicida, and live vaccine strain, as well as the LPS of E. coli, were able to induce abundant IL-1beta mRNA synthesis and intracellular pro-IL-1beta production, only live Francisella induced enhanced IL-1beta processing and release (51 +/- 10 vs. 7.1 +/- 2.1 ng/ml, for F. novicida vs. E. coli LPS; P = 0.0032). Cytochalasin D blocked the Francisella internalization and the Francisella-induced monocyte IL-1beta processing and release but not that induced by the exogenous stimulus E. coli LPS. Also, killing bacteria did not block uptake but significantly diminished the IL-1beta processing and release that was induced by Francisella. Blocking bacterial escape from the phagosome into the cytosol also decreased IL-1beta but not IL-8 release. These findings demonstrate that Francisella organisms efficiently induce IL-1beta processing and release in fresh monocytes by means of a sensing system that requires the uptake of live bacteria capable of phagosome escape.